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Development of a routine objective quality control program for diagnostic ultrasound

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Title:
Development of a routine objective quality control program for diagnostic ultrasound
Creator:
Mayani, Archana
Place of Publication:
[Gainesville, Fla.]
Publisher:
University of Florida
Publication Date:
Language:
English

Subjects

Subjects / Keywords:
Calipers ( jstor )
Gray scale ( jstor )
Image resolution ( jstor )
Image transducers ( jstor )
Imaging ( jstor )
Quality assurance ( jstor )
Signals ( jstor )
Transducers ( jstor )
Ultrasonography ( jstor )
Uniformity ( jstor )
Biomedical Engineering thesis, M.S ( lcsh )
Dissertations, Academic -- Biomedical Engineering -- UF ( lcsh )
OBJECTIVE, QC, ROUTINE, ULTRASOUND
Genre:
government publication (state, provincial, terriorial, dependent) ( marcgt )
bibliography ( marcgt )
theses ( marcgt )
non-fiction ( marcgt )

Notes

Summary:
ABSTRACT: This study was undertaken to develop a test methodology for medical diagnostic ultrasound whereby testing procedures could be reproducible and which lends itself to quantifiable and objective results. The purpose of the methodology was to provide a means by which ultrasound equipment could be monitored and assessed for performance variability over time. A total of six real-time ultrasound systems, manufactured by Acuson (Mountain View, CA) and GE Medical Systems (Milwaukee, WI), were used for development of the testing procedures. Operator selectable scanner controls were initially set and recorded to provide a clinically suitable image. Tests and measurements were performed using the GAMMEX RMI 403GS (Middleton, Wisconsin) Precision Multi-purpose Grey Scale Test phantom. All the images were accessed using the Shands Hospital web-based access system Medisurf manufactured by Algotec Systems (Duluth, Georgia). A database was prepared in Microsoft Excel to store all the quantitative information (test results and test settings) of each transducer at its various operating frequencies. The Analyze software system developed by The Biomedical Imaging Resource Department at the Mayo Foundation was used for all the quantitative analysis.
Summary:
ABSTRACT (cont.): Image quality analysis for this study was limited to field uniformity, maximum imaging depth, axial and lateral resolution determination, distance accuracy assessment, and anechoic object perception with grayscale evaluation. Test protocols developed for these purposes were designed based on the recommendations by the American Institiute of Ultrasound in Medicine (AIUM) Program. The quantitative results were compiled together and periodic trends were generated to study the behavior and the pattern of tests. Depending upon the performance of the transducer and the behavior of each QC trend with respect to the parameter variations, a distinct set of action levels and defect levels were formulated, always ensuring these are in line with AIUM recommendations. An automatic excel program developed using the recommended action levels was developed to serve as a useful tool for quantitative evaluation and automatic performance testing. Graphical representation of the data is presented and initial interpretation indicates that the stated goals of the study have been met. The methodology provides a means of monitoring diagnostic ultrasound scanners on a routine basis and provides quantitative, reproducible results.
Thesis:
Thesis (M.S.)--University of Florida, 2002.
Bibliography:
Includes bibliographical references.
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System requirements: World Wide Web browser and PDF reader.
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Mode of access: World Wide Web.
General Note:
Title from title page of source document.
General Note:
Includes vita.
Statement of Responsibility:
by Archana Mayani.

Record Information

Source Institution:
University of Florida
Holding Location:
University of Florida
Rights Management:
Copyright Mayani, Archana. Permission granted to the University of Florida to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
Embargo Date:
12/1/2003
Resource Identifier:
029834785 ( ALEPH )
80037355 ( OCLC )

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DEVELOPMENT OF A ROUTINE OBJECTIVE QUALITY CONTROL PROGRAM FOR DIAGNOSTIC ULTRASOUND By ARCHANA MAYANI A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2002

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To dearest Soni

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iii ACKNOWLEDGMENTS I would like to express deep appreciation to the following people who went above and beyond their responsibilities in assisting me during my graduate career: to Dr. Arreola for his never-ending encouragement, teachings and friendship, to Dr. Hintenlang for his constant guidance and support, to Dr. Bolch, Dr. Rill and to all the others who offered me their assistance. Very special thanks go to dear Kennita whose help cannot be half-reciprocated with a million thanks, and to Prashant for his patient listening and giving me and my equipment all the space that I ever wanted in our New York style office. Special gratitude goes to my Mother and all my near and dear back home in India for holding the fortress for me when I was ready to shake and fall. I would like to dedicate this thesis to all my friends for making a home for me away from home. I thank especially my friend and roommate, Sonali Narain, for her invaluable friendship, her time, and everything else that went along with being my friend.

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iv TABLE OF CONTENTS page ACKNOWLEDGMENTS..................................................................................................iii LIST OF TABLES...........................................................................................................viii LIST OF FIGURES............................................................................................................xi CHAPTER 1 INTRODUCTION AND BACKGROUND....................................................................1 Introduction................................................................................................................... ..1 Physics of Ultrasound......................................................................................................2 General Characteristics of Sound.............................................................................2 Generation of a Pressure Wave................................................................................3 Piezoelectric effect............................................................................................3 Characteristics of piezoelectric crystals............................................................4 The Ultrasonic Transducer.......................................................................................5 The Characteristics of an Ultrasonic beam...............................................................7 Interactions between Ultrasound and matter............................................................9 Reflection..........................................................................................................9 Refraction........................................................................................................13 Attenuation......................................................................................................14 Absorption.......................................................................................................15 Clinical Ultrasound.................................................................................................17 A – mode (Amplitude mode)..........................................................................17 B – mode (Brightness mode)...........................................................................20 M – mode (Motion mode)...............................................................................20 Doppler............................................................................................................21 Need for Quality Control and Maintenance in Medical Imaging..................................22 QC in Ultrasound: Motivation.......................................................................................24 Quality....................................................................................................................25 Service....................................................................................................................25 Safety......................................................................................................................25 Ultrasound Accreditation Programs..............................................................................25 American College of Radiology (ACR).................................................................26 General............................................................................................................26 Ultrasound guided breast biopsy accreditation program phantom..................26 Intersocietal Commission for the accreditation of vascular laboratories (ICAVL)27

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v American Institute of Ultrasound in Medicine (AIUM).........................................27 Literature Review..........................................................................................................27 2 METHODS AND MATERIALS..................................................................................30 General........................................................................................................................ ..30 Ultrasound Equipment and Transducers.......................................................................31 Description of the Phantom...........................................................................................35 Vertical Plane Target Group...................................................................................36 Horizontal Plane Target Groups.............................................................................37 Axial Resolution Target Group..............................................................................37 Gray Scale Targets.................................................................................................38 Medisurf....................................................................................................................... .40 Analysis Software: Analyze..........................................................................................41 Features:.................................................................................................................42 The User Interface...........................................................................................42 Multiple Volume Sharing................................................................................43 Analyze Modules....................................................................................................43 Analyze Main Control Panel...........................................................................43 Image Data Retrieval and Management..........................................................45 Image Data Loading and Storing....................................................................46 Image Mensuration and Quantitative Analysis...............................................46 Methodology: Description of Various Tests.................................................................48 Uniformity..............................................................................................................48 Depth of Penetration...............................................................................................50 Spatial Distance Fidelity:.......................................................................................52 Vertical Distance Accuracy.............................................................................52 Horizontal Distance Accuracy........................................................................54 Spatial Resolution: Axial And Lateral...................................................................56 Anechoic Object Imaging and Gray Scale Evaluation...........................................60 System Linearity.............................................................................................62 3 RESULTS..................................................................................................................... .64 Initial Image Assessment..............................................................................................64 Depth of Penetration......................................................................................................64 Spatial Distance Fidelity: Horizontal and Vertical Caliper Accuracy..........................65 Image Uniformity..........................................................................................................66 Anechoic Object Perception/ Gray Level Measurement...............................................70 Spatial Resolution: Axial Resolution and Lateral Resolution.......................................71 Axial resolution......................................................................................................71 Lateral Resolution..................................................................................................72

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vi 4 DISCUSSION...............................................................................................................75 Uniformity..................................................................................................................... 75 Depth of Penetration......................................................................................................76 Distance Accuracies: Horizontal and Vertical distance accuracies..............................77 Anechoic Object Perception and Gray Level Measurement.........................................78 Spatial Resolution: Axial and Lateral Resolution.........................................................79 Recommendations.........................................................................................................79 5 CONCLUSION.............................................................................................................80 Quality Control: Tolerance Levels................................................................................80 Selection of Action Levels.....................................................................................81 Image Uniformity...................................................................................................82 Depth of Penetration........................................................................................82 Horizontal and Vertical Caliper Accuracy......................................................83 Anechoic Object Perception and Gray Level Measurement...........................83 Axial Resolution..............................................................................................84 Lateral Resolution...........................................................................................84 Future Research.............................................................................................................85 APPENDIX A QC PROTOCOL..........................................................................................................87 Equipment Evaluation...................................................................................................87 Phantom Measurements................................................................................................88 Image Analysis Protocol........................................................................................88 Operator selectable system controls................................................................88 Time Gain Compensation................................................................................88 Output Power...................................................................................................88 Depth...............................................................................................................88 Gray Scale.......................................................................................................89 Edge.................................................................................................................89 Dynamic Range...............................................................................................89 Reject...............................................................................................................89 Scanning the Phantom............................................................................................89 Image collection.....................................................................................................90 Image analysis........................................................................................................90 Uniformity.......................................................................................................90 Distance accuracies.........................................................................................91 Spatial resolution.............................................................................................91 Anechoic object perception and Gray scale evaluation.................................92 Records and Scheduling................................................................................................92

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vii B EXCEL PROGRAM WORKSHEET...........................................................................93 C RESULTS...................................................................................................................11 1 LIST OF REFERENCES................................................................................................141 BIOGRAPHICAL SKETCH..........................................................................................143

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viii LIST OF TABLES Table page 1-1 The length of the Fresnel Zone to various sized transducers and frequencies..........9 1-2 Approximate acoustic impedance of various materials.............................................11 1-3 Reflection coefficients of various materials at a frequency of 1 Mhz.......................12 1-4 Attenuation coefficients for selected tissues at 1 Mhz..............................................15 1-5 Absorption coefficients for various materials at a frequency of 1 MHz...................17 2-1 Acuson transducers...................................................................................................33 2-2 LOGIQ 700 transducers............................................................................................34 3-1 Sample data for depth of penetration........................................................................65 3-3 Sample data for horizontal distance accuracies (in cm)............................................66 3-4 Sample data for uniformity measurements................................................................67 3-5 Sample data for uniformity measurements after taking the average.........................68 3-6 Sample data for gray scale evaluations.....................................................................70 3-7 Sample data for axial resolution measurements........................................................72 3-8 Sample data for lateral resolution measurements......................................................73 4-1 Estimated depths for frequencies..............................................................................77 4-2 Echo level measurements..........................................................................................78 5-1 Suggested action and defect levels............................................................................85 C-1 Vertical caliper accuracy test measurement..............................................................111 C-2 Horizontal caliper accuracy measurement.................................................................111 C-3 Brightness values for phantom objects......................................................................112

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ix C-4 Relative brightness values (to the background) for phantom objects........................113 C-5 Signal values in the selected ROIs............................................................................114 C-6 Average signal values in the selected ROIs..............................................................115 C-7 Maximum imaging depth..........................................................................................115 C-8 Axial resolution measurement...................................................................................116 C-9 Lateral resolution measurement at various depths....................................................116 C-10 Vertical caliper measurement at various depths........................................................117 C-11 Horizontal caliper measurement at various depths....................................................117 C-12 Brightness values for phantom objects......................................................................118 C-13 Relative (to the background) brightness values for phantom objects........................119 C-14 Signal values for selected ROIs.................................................................................120 C-15 Average signal values for selected ROIs...................................................................121 C-16 Maximum imaging depth measurement....................................................................121 C-17 Axial resolution measurement...................................................................................122 C-18 Lateral resolution measurement at various depths....................................................122 C-19 Vertical caliper measurement at various depths........................................................123 C-20 Horizontal caliper measurement at various depths....................................................123 C-21 Brightness values for phantom objects......................................................................124 C-22 Relative (to the background) brightness values for phantom objects........................125 C-23 Signal values for selected ROIs.................................................................................126 C-24 Maximum imaging depth measurement....................................................................127 C-25 Axial resolution measurement...................................................................................127 C-26 Lateral resolution measurement at various depths....................................................128 C-27 Vertical caliper measurement at various depths........................................................129 C-28 Horizontal caliper measurement at various depths....................................................129

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x C-29 Brightness values for phantom objects......................................................................130 C-30 Relative (to the background) brightness values for phantom objects........................131 C-31 Signal values for selected ROIs.................................................................................132 C-32 Average signal values for selected ROIs...................................................................133 C-33 Maximum imaging depth measurement....................................................................134 C-34 Axial resolution measurement...................................................................................134 C-35. Lateral resolution measurement at various depths....................................................135 C-36 Vertical caliper measurement at various depths........................................................136 C-37 Horizontal caliper measurement at various depths....................................................136 C-38 Brightness value for phantom objects.......................................................................137 C-39 Relative (to the background) brightness value for phantom objects.........................138 C-40 Signal value for phantom objects..............................................................................139 C-41 Maximum imaging depth measurement....................................................................139 C-42 Axial resolution measurement...................................................................................140 C-43 Lateral resolution measurement at various depths....................................................140

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xi LIST OF FIGURES Figure page 1-1 Mechanical forces acting upon piezoelectric crystal.................................................3 1-2 Applied voltage to piezoelectric crystal....................................................................4 1-3 Ultrasound transducer...............................................................................................6 1-4 The Fresnel and Fraunhofer zones of an ultrasound beam........................................8 1-5 Reflection and Refraction of sound waves................................................................14 1-6 The A-scan................................................................................................................ 19 1-7 A B-scan is obtained by superimposing several A-scans .........................................20 1-8 Doppler effect............................................................................................................ 21 2-1 Acuson.................................................................................................................... ...32 2-2 LOGIQ 700................................................................................................................3 2 2-3 GAMMEX RMI 403GS phantom.............................................................................35 2-4 Axial resolution target group.....................................................................................37 2-5 Gray scale targets......................................................................................................38 2-6 Schematic model of RMI 403GS..............................................................................39 2-7 Medisurf image viewing............................................................................................41 2-8 Analyze main control panel.......................................................................................44 2-9 Import-export window...............................................................................................45 2-10 Image mensuration....................................................................................................47 2-11 Phantom section for uniformity.................................................................................49 2-12 Ultrasound image of uniformity test showing the ROIs............................................50 2-13 Phantom section for depth of penetration.................................................................51 2-14 Ultrasound image showing the depth of penetration measurement...........................52 2-15 Phantom section for vertical distance accuracy.........................................................53 2-16 Ultrasound image of vertical distance accuracy measurement..................................54

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xii 2-17 Phantom section for horizontal distance accuracy....................................................55 2-18 Ultrasound image showing horizontal distance accuracy measurement...................56 2-19 Phantom section for axial and lateral resolution targets............................................58 2-20 Ultrasound images showing axial and lateral resolution measurements...................59 2-21 Phantom section for anechoic image perception and gray scale evaluation..............60 2-22 Ultrasound image showing ROIs for anechoic object perception and......................61 2-23 S-shaped curve translates echo level into brightness levels on the video display.....62 2-24 Changes in the shape of the S-curve result in different brightness levels.................63 3-1 Graphical representation of data in Table 3-1...........................................................65 3-2 Graphical representations of data in Table 3-5.........................................................69 3-3 S-curve for phase I....................................................................................................71 3-4 Graphical representation for Table 3-7.....................................................................72 3-5 Graphical representation of data in Table 3-8...........................................................74 5-1 Graphical User Interface (GUI) in Matlab for an automated US QC package..........86

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xiii Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science DEVELOPMENT OF A ROUTINE OBJECTIVE QUALITY CONTROL PROGRAM FOR DIAGNOSTIC ULTRASOUND By Archana Mayani December 2002. Chairman: David Hintenlang, Ph. D. Major Department: Biomedical Engineering This study was undertaken to develop a test methodology for medical diagnostic ultrasound whereby testing procedures could be reproducible and which lends itself to quantifiable and objective results. The purpose of the methodology was to provide a means by which ultrasound equipment could be monitored and assessed for performance variability over time. A total of six real-time ultrasound systems, manufactured by Acuson (Mountain View, CA) and GE Medical Systems (Milwaukee, WI), were used for development of the testing procedures. Operator selectable scanner controls were initially set and recorded to provide a clinically suitable image. Tests and measurements were performed using the GAMMEX RMI 403GS (Middleton, Wisconsin) Precision Multi-purpose Grey Scale Test phantom. All the images were accessed using the Shands Hospital web-based access system Medisurf manufactured by Algotec Systems (Duluth, Georgia). A database was prepared in

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xiv Microsoft Excel to store all the quantitative information (test results and test settings) of each transducer at its various operating frequencies. The Analyze software system developed by The Biomedical Imaging Resource Department at the Mayo Foundation was used for all the quantitative analysis. Image quality analysis for this study was limited to field uniformity, maximum imaging depth, axial and lateral resolution determination, distance accuracy assessment, and anechoic object perception with grayscale evaluation. Test protocols developed for these purposes were designed based on the recommendations by the American Institiute of Ultrasound in Medicine (AIUM) Program. The quantitative results were compiled together and periodic trends were generated to study the behavior and the pattern of tests. Depending upon the performance of the transducer and the behavior of each QC trend with respect to the parameter variations, a distinct set of action levels and defect levels were formulated, always ensuring these are in line with AIUM recommendations. An automatic excel program developed using the recommended action levels was developed to serve as a useful tool for quantitative evaluation and automatic performance testing. Graphical representation of the data is presented and initial interpretation indicates that the stated goals of the study have been met. The methodology provides a means of monitoring diagnostic ultrasound scanners on a routine basis and provides quantitative, reproducible results.

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1 CHAPTER 1 INTRODUCTION AND BACKGROUND Introduction Medical ultrasound or sonography is a non-invasive, real-time, tomographic soft-tissue imaging modality, which has a wide array of clinical applications, both as a primary modality and as an adjunct to other diagnostic procedures. Advancements in the field of diagnostic ultrasound have led to increased use of this modality in many clinical applications. Ultrasound is often considered the preferred imaging modality because of its ability to provide continuous, real-time images without the risk of ionizing radiation and at a lower cost than computed tomography (CT) or magnetic resonance imaging (MRI). As with any modality, an increase in use is accompanied by an increased need for performance testing in order to ensure the repeatability and accuracy of the results. Because the final image is the basis for diagnostic decisions, the image quality produced by a scanner provides the most important information in testing scanner performance. A procedure for evaluating image quality has been outlined by National Council on Radiation and Protection and Measurements (NCRP) and Amreican Institute of Ultrasound in Medicine (AIUM) (NCRP 1988; AIUM 1998), but the tests listed in these papers rely heavily on the subjectivity of the examiner in providing results. Adhering to the definition of quality control (Cameron JR. & Skofronick. JG, 1978), the test methodology developed in this thesis includes periodic monitoring of performance parameters under clinically applicable, consistent conditions using known testing standards (AIUM 1998). Testing

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2 procedures are described for assessing spatial resolution (lateral and axial), field uniformity, spatial distance fidelity (horizontal and vertical), gray scale evaluation, anechoic object perception and depth of penetration. A description of the conventional methods as well as the methods developed in this research is provided in Chapter 2. The early sections of this thesis serve to introduce the physical principles and instrumentation of ultrasonic imaging as they apply to medical diagnosis. A description of image assessment and quality control are also included followed by detailed descriptions of testing procedures developed in this study. Finally, sample data obtained using the test methodology is included to demonstrate the type of quantitative data available via these methods from which quality assurance implications can be made as they pertain to a particular institution. Physics of Ultrasound General Characteristics of Sound A sound wave is a physical phenomenon whereby energy is transferred from one point to another via mechanical disturbances, or vibrations. The vibrations cause local increases in density relative to the propagation medium, called compressions, and relative decreases, called rarefactions, which spread outward as a longitudinal wave. The intensity of a sound wave is the energy passing through watts per square meter. For a plane wave, the intensity, I, is given by equation 1-1 I = (0.5) Z (A ) 2, 1-1 where A is the maximum displacement amplitude of the atoms or molecules from their equilibrium position, Z is the acoustic impedance, and is used to denote angular frequency.

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3 Generation of a Pressure Wave Piezoelectric effect Certain materials (natural or synthetic) on application of an electric field cause a change in their physical dimensions, and vice versa. This is the “piezoelectric effect”1 (Currey et al, 1990). Compression Equilibrium Expansion No surface charge Figure 1-1. Mechanical forces acting upon piezoelectric crystal: The piezoelectric crystal produces a surface charge in response to incident mechanical energy (e.g., an ultrasound echo with realignment of the internal electrical dipoles during compression or expansion) (Currey et al, 1990) 1 The effect was first described by Pierre and Jacques Curie in 1880. “Piezo” means pressure, so piezoelectricity implies to the pressure electricity

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4 Compression Equilibrium Expansion No surface charge Figure 1-2. Applied voltage to piezoelectric crystal: An external voltage source applied to the crystal surface causes compression or expansion of the crystal by realignment of the internal electrical dipoles (Currey et al., 1990). Characteristics of piezoelectric crystals Figure 1-1 shows that the piezoelectric materials are made up of innumerable dipoles arranged in a geometric pattern. As shown in Figure 1-2, the positive and negative ends are arranged so that an electric field will cause them to realign, thus changing the dimensions of the crystal. The illustration shows a considerable change in thickness, but actually the change is only a few microns. If the voltage is applied in a sudden burst, or pulse, the crystal vibrates like a cymbal that has been struck a sharp blow and generates sound waves. Figure 1-1 shows that when a piezoelectric crystal is exposed to a mechanical force (e.g., sound waves), the interaction causes a physical compression or decompression of

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5 the crystal element. This compression forces the dipoles to change their orientation, which induces a voltage. This voltage, if amplified, can serve as the signal for display on a television monitor. Thus, the compression force and associated voltage are responsible for the name piezoelectricity, implying pressure electricity. Some naturally occurring materials such as quartz possess piezoelectric properties but most crystals used in medical ultrasound are man-made. This group of artificial piezoelectric materials are known as ferroelectrics. Barium titanate was the first of the ceramic ferroelectrics to be discovered. This has been largely replaced by lead zirconate, commonly known as PZT.2 The Ultrasonic Transducer Conventional ultrasound units are comprised of a transducer, pulse generator, demodulation, amplification, time gain compensation (TGC), digital scan conversion system, memory storage, image processing, and a display. More complex ultrasound systems may also have Doppler, color flow, or other electronic features. The ultrasonic transducer is an extremely important and critical part of any ultrasonic device. Figure 1-3 shows a schematic diagram of an ultrasonic transducer. An ultrasonic transducer is made up of several active crystals, a backing, and wearplate. The backing is most commonly a highly attenuative and very dense material and is used to dampen the vibrations of the transducer crystal by absorbing the energy that radiates from the back face of the piezoelectric element. The acoustic impedance of the backing material is made to match that of the piezoelectric crystal, resulting in a highly damped transducer with excellent resolution. 2 PZT is registered trade name of PZT materials from the Cleveite Corporation

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6 Wearplates are selected to generally protect against wear and corrosion (Currey et al., 1990). Figure 1-3. Ultrasound transducer (Currey et al., 1990) Array transducers with multiple piezoelectric crystal elements are more prevalent for dynamic ultrasound imaging. An array of transducer is composed of many small rectangular transducer elements (about 2 x 10 mm) arranged adjacent to each other. Linear phased array transducers The linear phase array is most common, and typically has 32, 64, or 128 elements linearly arranged in a protective housing. Groups of transducers are fired simultaneously in a sequential scan sequence. Each group sends and receives a sound pulse before the next group is activated. An advantage of the rectangular display is the wide field of view (FOV) for regions close to the transducer with uniform sampling across the image.

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7 Phased array transducers Phased Array transducer operation is accomplished by pulsing the individual elements with a variable timing delay. The curvilinear arrangement of the transducer assembly in phased array operation assists acquisition of data over a much larger FOV. Phase variations between the individual beams form constructive and destructive interference patterns. A similar timing delay during the reception of the signal must be applied between the elements as well. Sector, rectangular, and trapezoidal scan patterns can be produced. Annular array transducers Annular arrays are made with concentric piezoelectric rings, and are operated with phased pulsing between rings. The transducer housing is moved mechanically to the beam, but the focusing is accomplished by electronic delays between the individual transducer elements, typically composed of 5 – 12 rings. The Characteristics of an Ultrasonic beam Piezoelectric crystals behave as a series of vibrating points and therefore the wave fronts are not uniform, close to the crystal.

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8 Figure 1-4. The Fresnel and Fraunhofer zones of an ultrasound beam (Currey et al., 1990) The intensity of ultrasound varies longitudinally along the length of the beam. The simplest way of depicting an ultrasound beam is that shown in the Figure 1-4, in which the beam is drawn as a parallel bundle for a certain distance, beyond which it disperses (Cameron JR. & Skofronick. JG, 1978). The parallel component is called the near or Fresnel zone. The diverging portion of the beam is called the Far or Fraunhofer zone. The length of the Fresnel zone is determined by equation 1-2 using the diameter of the transducer and the wavelength of the ultrasound. xÂ’ = D2 1-2 4 where xÂ’ = length of the Fresnel zone in cm, D is the radius of the transducer in cm and is the wavelength in cm. Table 1-1 shows the length of the Fresnel zone for various wavelengths and transducer diameters. Length of near field (xÂ’) 42D Far field D A plane wave front is transmitted Angle ! " # $ % & D 22 . 1 arcsin Ultrasound Transducer

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9 Table 1-1. The length of the Fresnel Zone to various sized transducers and frequencies LENGTH OF FRESNEL ZONE (CM) Diameter Of Transducer (cm) FREQUENCY (MHZ) 0.5 1.0 1.5 2.0 2.5 1.0 0.37 1.6 3.4 6.5 10 1.5 0.58 2.4 5.1 9.7 15 2.0 0.79 3.2 6.8 13.0 20 2.5 1.01 4.0 8.5 16.0 25 5.0 2.01 8.1 17.0 32.0 50 7.5 2.97 11.9 25.0 48.0 75 The zone is longest with a large transducer and high frequency sound, and shortest with a small transducer and low frequency. The size of the angle of divergence, beyond the Fresnel zone, is determined as follows: sin = 1.22 x 1-3 D where stands for dispersion angle of the far zone, is the wavelength measured in mm and D is the diameter of transducer in mm. Interactions between Ultrasound and matter As ultrasound propagates through a medium there are three possible interactions that take place: (1) reflection, (2) refraction, and (3) attenuation (Currey et al., 1990) Reflection is the return of the incident ultrasound energy as an echo, directly back to the transducer when interacting at the boundary with normal (perpendicular) incidence. Refraction occurs when sound waves meet a tissue interface boundary at an angle other than 90o. Attenuation refers to the loss of intensity of the ultrasound beam resulting form absorption and scattering events. Reflection In ultrasound, the reflected portion of the beam produces the image. Transmitted sound does not contribute to image formation, but transmission must be strong enough to

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10 produce echoes at deeper tissue depths. The percentage of the beam reflected at tissue interfaces depends on (1) the tissueÂ’s acoustic impedance, and (2) the beams angle of incidence. Acoustic Impedance Acoustic impedance is a fundamental property of matter. The impedance of a material is the product of its density and velocity of the sound in the material as indicated by equation 1-4. z = v 1-4 where z is acoustic impedance (3Rayls/s), is the density of the material (g/cm2) and v is the velocity of sound (cm/sec).The velocity of sound in tissue is fairly constant over a wide range of frequencies and hence the substanceÂ’s acoustic impedance is a constant. Table 1-2 lists the acoustic impedance, in Rayls, of various materials, including several body tissues and some piezoelectric materials used in ultrasound transducers (Currey et al., 1990). 3 The unit for acoustic impedance in the CGS system, the Rayl, is defined as g/cm2 x 105.the Rayl is named in honor of the English physicist Lord Rayleigh, Nobel prize winner in 1904.

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11 Table 1-2. Approximate acoustic impedance of various materials MATERIAL ACOUSTIC IMPEDANCE (Rayls-g/cm2 x 10-5) Air 0.0004 Fat 1.38 Castor Oil 1.4 Water (50o C) 1.54 Brain 1.58 Blood 1.61 Kidney 1.62 Liver 1.65 Muscle 1.70 Lens of Eye 1.84 Piezoelectric polymers 4.0 Skull (bone) 7.8 Quartz 15.2 Mercury 19.7 PZT – 5A 29.3 PZT – 4 30.0 Brass 38.0 The amount of reflection is determined by the angle of incidence between the sound beam and the reflecting surface. But also by equation 1-5, the higher the angle of incidence, the less the amount of reflected sound. When a sound beam strikes a smooth interface that is perpendicular to the beam, the amount of reflection is given by equation 1-5 R = (z 2 – z 1 ) 2 x 100 1-5 (z 2 + z 1) 2

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12 where R is the percentage of beam reflected, z1 and z2 are the acoustic impedances of medium 1 and 2 respectively. Typical reflection coefficients are listed in table 1-3. Table 1-3. Reflection coefficients of various materials at a frequency of 1 Mhz TISSUE INTERFACE REFLECTIVITY Brain – skull bone 0.66 Fat – bone 0.69 Fat – blood 0.08 Fat – kidney 0.08 Fat – muscle 0.10 Fat – liver 0.09 Lens – aqueous humor 0.10 Lens – vitreous humor 0.09 Muscle – blood 0.03 Muscle – kidney 0.03 Muscle – liver 0.01 Soft tissue (mean) – water 0.05 Soft tissue – air 0.9995 Soft tissue – piezoelectric crystal 0.89 It is also possible to calculate the amount of transmission of a sound beam that strikes a smooth interface perpendicular to the beam. The transmission coefficient is given by equation 1-6. T = 4 z 1 z 2 x 100 1-6 (z1 + z2)2 where T represents the percentage of beam energy transmitted and z1 and z2 are the acoustic impedances of medium 1 and medium 2 respectively. and thus, R + T = 1 1 -7

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13 Refraction Refraction is the change in direction of the transmitted ultrasound energy that occurs at a boundary interface. The bending of sound waves by refraction requires a nonperpendicular incidence of the beam, and different propagation speeds of the two adjacent tissues. The change in direction results from a wavelength change in the second medium to accommodate a change in speed (frequency stays constant). Figure 1-5 is a good example of reflection and refraction interactions. As seen in the figure the angles of incidence, reflection, and transmission (refraction) are defined relative to the perpendicular to the boundary. The angle of transmission is dependant on the propagation speeds of the two materials, according to the SnellÂ’s Law. SnellÂ’s law is given in the equation 1-8. sin t = sin i x v 2 1-8 v1 where v1 and v2 are the propagation speeds in medium 1 and 2, respectively, and where medium 2 carries the transmitted ultrasound energy.

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14 Figure 1-5. Reflection and Refraction of sound waves Attenuation Attenuation occurs in addition to the reflection and refraction interactions. The viscosity and stiffness of a medium, as well as its scattering properties give rise to the attenuation of the ultrasound intensity as the sound propagates through the medium. Attenuation is characterized by the attenuation coefficient in units of dB/cm, which is a measure of the relative intensity loss per centimeter of travel. The attenuation coefficients are given in the table 1-4.

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15 Table 14. Attenuation coefficients for selected tissues at 1 Mhz Tissue Attenuation Coefficient, Db/ Cm @ 1 Mhz Liver 0.7 0.94 Fat 0.6 0.95 Kidney 0.9 1.0 Brain 0.8 0.9 Soft tissue (average) 0.5 1.0 Absorption Absorption of ultrasound in fluids is a result of frictional forces that oppose the motion of the particles in the medium. The energy removed from the ultrasound beam is converted into heat. The mechanisms involved in absorption are rather complex and there are three factors that determine the amount of absorption: (1) the frequency of the waves, (2) the viscosity of the conducting medium, and (3) the “relaxation time” of the medium. Increasing viscosity decreases particle freedom and increases internal friction. This internal friction absorbs the beam, or decreases its intensity, by converting acoustic energy into heat. In liquids, which have low viscosity, very little absorption takes place. In soft tissues viscosity is higher and a medium amount of absorption occurs, whereas bone shows high absorption of ultrasound. The relaxation time is the time that it takes for a molecule to return to its original position after it has been displaced and is constant for any particular material. It refers to the resilience of a material. When a molecule with a short relaxation time is displaced by a longitudinal compression wavefront, the molecule has time to return to its resting state before the next compression wavefront arrives. A molecule with a longer relaxation time may not be able to return completely before a second compression wavefront arrives.

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16 When this happens, the compression wave is moving in one direction and the molecule in the opposite direction. More energy is required to reverse the direction of the molecule than was needed to move it originally. The additional energy is converted to heat. The frequency of the sound affects the amount of absorption produced by the viscosity of the material. The higher the frequency, the more it is affected by the drag of a viscous material. Frequency also affects the amount of absorption produced by the relaxation time. At low frequencies, molecules have sufficient time to relax between cycles but, as frequencies increase, the relaxation time consumes a greater and greater proportion of the total cycle. Table 1-5 lists absorption coefficients for various materials.

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17 Table 1-5. Absorption coefficients for various materials at a frequency of 1 MHz Material Absorption Coefficient (dB/cm) Lung 41 Skull (bone) 20 Air 12 Muscle (across fiber) 3.3 Lens of eye 2.0 Kidney 1.0 Castor oil 0.95 Liver 0.94 Brain 0.85 Fat 0.63 Blood 0.18 Aluminum 0.018 Water 0.0022 Mercury 0.00048 Clinical Ultrasound Clinical ultrasound devices collect and present the image data in one of four modes: (1) Amode, (2) B-mode, (3) M-mode and (4) Doppler mode. Other derived modes are possible. One particularly useful mode is the C-mode in which an image is derived by either placing a receiver opposite a transmitter (and ignoring reflections), or by deriving the cross-section C-mode data from the three-dimensional imaging (Ultrasonics in Clinical Diagnosis, 1983). Most modern systems can generate multiple modes, and the choice is left to the user. A – mode (Amplitude mode) A – mode is the most basic mode and intrinsic to all other modes of data acquisition. As echoes return from tissue boundaries at perpendicular incidence, their impact on the

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18 transducer crystal produces a voltage that is proportional to the echo intensity, which in turn is a function of the attenuation coefficient of tissues and acoustic impedance differences between the tissue boundaries. As the round-trip time equates to depth, the tissue interfaces along the path of the ultrasound beam can be separated and distances can be determined. The phenomenon is graphically explained in figure 1-6. The ultrasound beam produced by the transducer head propagates into the tissue and is partly reflected when a tissue interface between acoustic impedance is encountered. The reflections are then detected as they return to the transducer. The physically inevitable attenuation of the ultrasound beam implies that the further the echo has traveled before returning to the transducer head, the smaller the detected amplitudes. As a consequence, tissue interfaces having the same reflection coefficient, but located at different depths, should appear differently on the monitor. The closer one should have the highest amplitude. Regardless of depth however, equally reflective interfaces can be presented with the same amplitude when looking at an A-scan. This is achieved by using TGC (time gain compensation) amplifiers, which compensate for the attenuation so that long distance echoes are amplified more than close range echoes. Equally reflective interfaces will therefore be displayed with the same amplitude regardless of depth. The amplitudes of the reflections still correspond to the acoustic properties of the encountered interfaces though. An interface, at which the reflection is great, appears with large amplitude when performing an A-scan. Thus, in the A mode or, amplitude mode, the display contains information about the depth of the structures and the amplitude of the echo. A – mode is used in

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19 ophthalmology, echoencephalography, echocardiology, and a scan adjunct to B-mode displays when accurate depths are required. = Tissue type 1 = Tissue type 2 (a) Transducer (b) Detected TGC Filter Reflections t,x (c) Displayed Signal t,x Figure 1-6. The A-scan: (a) Reflections from interfaces are (b) detected and time-gaincompensation filtering is applied. This enables reflections from equally reflective interfaces to be (c) displayed with equal amplitude

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20 B – mode (Brightness mode) B – scan or B – mode is the generic term used for mapping the acoustic impedance variation of the tissue into a two-dimensional display. In other words B-mode produces a picture of a slice of a tissue. By stepping the angle of an A-scan and simultaneously superimposing the A-scans as a function of spatial orientation a fan formed 2-dimensional view of the area covered can be achieved. This is the concept of a B-scan, as illustrated in figure 1-7. Figure 1-7. A B-scan is obtained by superimposing several A-scans taken from different angles It gives a tomographic slice image of the underlying tissue. B-mode greatly expanded the role of the ultrasound as a diagnostic tool, especially in abdominal cases. M – mode (Motion mode) M – mode converts the variations in signal amplitude of the A – mode line into a series of dots along a display oscilloscope whose brightness corresponds to the amplitude. The transducer continuously sends pulses to a given area of the patient from a fixed position with constant pulse repetition frequency. The echo brightness for each A – Air Transducer beam performing a scanning motion Tissue A-scan beam

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21 line is displayed vertically, and each sequential A-line is positioned horizontally. Deflection of the dot pattern across the display screen provides motion display of the internal anatomy, since any moving reflectors along the path of the ultrasound beam will vary the range of echoes with a corresponding motion of the dots. Although an intermediate imaging mode, M – mode is particularly valuable for the analysis of valve leaflet motion and cardiac studies. Doppler The Doppler effect4 is a change in the perceived frequency of sound emitted by a sound source, which is moving relative to the detector. Figure 1-8. Doppler effect In figure 1-8, a vibrating source (with velocity s) produces a series of concentric waves, all moving out from the center, with the oldest in the most peripheral location (time 1) and the newest at the center (time 6). The velocity of the sound in the particular medium and the frequency of the oscillator determine the wavelength ( ), or distance between crests. In figure 1-8, the sound source is moving to the right as it vibrates. 4 The Doppler effect was first described by Christian Doppler in 1843

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22 If the relative speed between the source and the observer is V and the speed of propagation of the ultrasound is s and the Doppler Shift from the emitted frequency o is given in equation 1-9. = + o [V ] 1-9 [ s] where the plus sign applies when source and observer are getting closer and the negative sign when they are moving apart. Doppler techniques are used to study motion, primarily that of the circulatory system. Need for Quality Control and Maintenance in Medical Imaging Rising health-care costs and access to health care for the uninsured have been major focuses of health-care policies in the 1990s. Before that the advent of diagnoses-related groups began to heighten awareness that the health-care dollar and the resources to provide and receive health care are finite. It also became apparent that patient outcomes could be quantified and correlated with particular treatment regimens. The American College of Radiology (ACR) has developed Standards, Appropriateness Criteria, Accreditation programs, and various other resources to promote quality patient care in medical imaging. They are being developed and implemented to define the most efficient and appropriate patient care delivery methods. ACR accreditation programs exist to evaluate specific components of medical imaging modalities to determine compliance with standards that, when implemented by qualified individuals, are anticipated to result the best patient outcomes. In a variety of health care delivery settings, radiologists, medical physicists, imaging technologists and radiology nurses work together to provide patient care while rendering

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23 critical diagnostic information to the primary care physician, or by performing interventional procedures. The importance of timely, accurate medical imaging procedures has shown improvements in guiding appropriate management; minimizing hospital stays; and providing invasive procedures. Medical Imaging services provide a prime example of the various levels of on going monitoring necessary to achieve and maintain quality services in a user-friendly environment. It is generally accepted that there are several components to providing quality service. Among these are: staff who are qualified and skilled in applying their expertise to provide a service, equipment and support services that are functioning effectively, and consistent patient care delivery which meets high standards. In the case of medical imaging, some basic indicators of quality include, among others, timely delivery of written examination results, comparison with prior examinations, integration of the findings of any modalities used, and accurate conclusions based on integration of the clinical presentation of the patient. To provide this consistency and the highest level of quality possible, the medical imaging practice must be monitored. The various levels of monitoring include: Quality Control (QC) Quality Assessment and Improvement. Continuous Quality Improvement /Total Quality Management (CQI/TQM) Focused Studies. Examples of Quality Control in medical imaging include: acceptance testing, preventive maintenance, verifying shielding equipment for integrity, equipment calibration, measuring processor characteristics in comparison to accepted parameters,

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24 acceptance testing, measuring radiation exposure for each examination performed on each machine, recording fluoroscopy times, standardized examination performance protocols, and following radiation safety procedures such as film-badge exposure monitoring. QC in Ultrasound: Motivation Advancements in the field of diagnostic ultrasound have led to increased use of this modality in many clinical applications. Ultrasound is often considered the preferred imaging modality because of its ability to provide continuous, real time images without the risk of ionizing radiation and at a lower cost than a Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) scan. As with any modality, an increase in use is accompanied by an increased need for performance testing in order to ensure the repeatability and accuracy of the results. Because the final image is the basis for diagnostic decisions, the image quality produced by a scanner provides the most important information in testing scanner performance (NCRP, 1988). It could be argued that there is no need for US QC testing because (1) the new machines are very reliable and rarely break down, and (2) the sonographer will detect image quality problems during normal scanning. Although both of these statements may often be true, they do not necessarily negate the utility of US QC tests. A primary reason is that a set of periodic definitive measurements for each transducer and US unit can identify degradation in image quality before it affects patient scans. Another reason is that when equipment malfunction is suspected, QC tests can be employed to identify the source of the malfunction. Even equipment that is under a warranty or service contract should be checked periodically. QC tests can verify that equipment is operating correctly

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25 and identify trends in degrading performance, permitting preventive repairs to be made prior to a system failure. A quality assurance (QA) program involves many activities including: quality control testing, preventive maintenance, equipment calibration, in-service education of sonographers, bid specification writing and bid response evaluation, acceptance testing of new equipment, and evaluation of new products. The other benefits of a QA program include: Quality The efficient execution of a QC program ensures that consistent quality is maintained in all the images generated by the facility. This would imply that physicians reviewing the highest quality images impart patients the best possible service. Service It is estimated that using QC validated equipment sonographers would experience less down time thereby reducing possible inconvenience to the patients. Safety A safe working environment could be generated and enhanced by early detection of failures in electrical connections, mechanical assembly and equipment cleanliness. Ultrasound Accreditation Programs Several leading organizations have instituted voluntary accreditation programs and the importance of QA in these programs is growing. While the industry works towards internal regulation the federal government is beginning to involve itself in ultrasound QA issues. Standards affecting the subject of ultrasound QA have their genesis in three principal organizations listed below. 1. American College of Radiology (ACR)

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26 a. General b. Biopsy 2. Intersocietal Commission for the accreditation of vascular laboratories (ICAVL) 3. American Institute of Ultrasound in Medicine (AIUM) Accreditation offers practices an opportunity to improve their service through combination of self-study and peer review. With a better idea of their own strengths and weaknesses, accredited practices can improve skills and offer the patient a higher level of service. The accreditation programs are voluntary by nature. American College of Radiology (ACR) General Building on the success of the ACR Mammography Accreditation Program in 1995, the ACR embarked on a program to offer an accreditation program for US with the goal of improving the practice of ultrasound imaging. The ultrasound assurance program will evaluate the qualifications of personnel, equipment, image quality, and quality control measures. Ultrasound guided breast biopsy accreditation program phantom The ACR sponsors an accreditation program for facilities performing ultrasoundguided fine needle aspiration control (FNAC) and ultrasound guided core biopsy. The program encompasses: Personnel qualifications Equipment Quality assurance Quality Control

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27 Clinical Images Intersocietal Commission for the accreditation of vascular laboratories (ICAVL) ICAVL is a n independent commission established with the support of sponsoring organizations concerned or involved with vascular medicine. The purpose of this commission is to provide a mechanism for accreditation of facilities, which perform comprehensive non-invasive testing for vascular diseases. Accreditation is offered in the following areas: extracranial cerebrovascular, intracranial cerebrovascular, peripheral arterial, peripheral venous, and visceral vascular testing. Although the accreditation process is voluntary, Medicare and Medicaid require all vascular labs to be accredited by a certain date in order to continue to be reimbursed. American Institute of Ultrasound in Medicine (AIUM) AIUM`s “Ultrasound Practice Accreditation” is the central part of its voluntary peer review system of accreditation. The process documents the analysis by the clinic’s personnel of how the clinic complies with the guidelines and standards of AIUM.. the application ensures that the practice meets the requirements for conducting effective US examinations in every one of the major categories: personnel, physical facilities, documentation and procedures safeguarding patients, ultrasound personnel, and equipment. Literature Review Advancements in the field of diagnostic ultrasound have led to increased use of this modality in many clinical applications. As with any modality, an increase in use is accompanied by an increased need for performance testing in order to ensure the repeatability and accuracy of the results. Because the final image is the basis for

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28 diagnostic decisions, the image quality produced by a scanner provides the most important information in testing equipment performance. A procedure for evaluating image quality was outlined in NCRP Report # 99 in 1988, but the tests listed in this report rely on the subjectivity of the examiner in providing results (NCRP Report # 99). The report includes uniformity test and contrast evaluation and assessment of spatial resolution. Detailed testing procedures for quantitative image evaluation have been published by Kollmann (1994, 2000 (a)). Kollmann has published tests along with suggested tolerance levels for the Austria facility but a scheme for routine quantitative analysis has not yet been fully developed. Kollmann describes the procedures for spatial fidelity test, maximum imaging depth test, spatial resolution tests and caliper accuracy test. However, the spatial fidelity test procedures generate the limiting resolution for the system and not the actual resolution of the system. Also there was no way to double check whether the caliper accuracy test is providing accurate measurements. Barret et al. (1993) went on to publish a paper on the quality assurance of ultrasound imaging instruments by monitoring the monitor. A QA scheme was described along with the procedures necessary to obtain a repeatable measurement of the image so that comparisons with earlier good images can be made. The paper discusses the importance of acceptable image quality and contrast and resolution issues of the monitor. It establishes a brief outline of the PACS testing program. Metcalfe and Evans (1991) studied the relationship between routine ultrasound quality assurance parameters and subjective operator image assessment. He studied lateral resolution and perceived definition, dynamic range and subjective gray level assessment,

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29 and slice thickness and the overall image quality appraisal showed very poor correlation. He deduced that other QA parameters are needed to quantify good image quality as defined by the operators. The paper investigates the contrast offered by the ultrasound equipments and also relates the contrast to noise ratio to gray levels and came up with a subjective scheme for assessing gray level range of the equipment. Goodsitt et al. prepared ultrasound QA task group report “ Real-time B-mode ultrasound quality control test procedures” in 1998. The report discusses all the subjective QC tests in detail and recommends equipment test procedures with suggested action and tolerance levels. It lays a good groundwork scheme for any basic QC Program with its vivid description of various phantom designs and all subjective QC tests including caliper accuracy, depth of penetration, slice thickness measurement, dead zone measurement, spatial resolution and anechoic object imaging. The scheme proposed is routine, though subjective in nature. In general, all these authors have proposed quality control programs but Kollmann et al. (2000, (b)) has published the paper that looks at a clinical attempt to field a clinical quality control program. A detailed and structure test protocol was developed. The parameters were measured every 3 months by the clinical staff. The results were assessed for performance variability.

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30 CHAPTER 2 METHODS AND MATERIALS The implementation of a routine quality control program is necessary to ensure that an instrument is operating consistently at its expected performance level (Kollmann C., 1994). Acceptable working definition for quality control is “the periodic monitoring of a given performance parameter for a diagnostic instrument under consistent conditions using known testing standards to assure that this parameter has not degraded”. The tests developed in this work were designed to satisfy the conditions specified by this definition. General A total of six ultrasound machines consisting of three Acuson models and three GE 700s along with about 15 dual frequency transducers, and 6 sets of monitors were evaluated and followed up for 12 months. The sonographers generated all the phantom scans required for qualitative and quantitative assessments, throughout the year. Also the sonographers were rotated in different facilities in order to achieve subjective difference in the scans. The systems are identified as SUFAcI, SUFAcII, PAICAc, SUFGE700I, SUFGE700II, and SCCGE700 for reference, suggesting the location and the model of the equipment. For example, SUFAcI would imply the acuson (Ac) equipment # 1 (I) at Shands Hospital at University of Florida (SUF). SUFGE700I would similarly inform us that the equipment under consideration is a GE 700 and is located at the Shands facility at University of Florida. PAICAc stands for the acuson equipment at Park Avenue Imaging

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31 Center (PAIC) and SCCGE700 is the GE equipment located at Shands Cancer Center (SCC). During this period, quality assessment tests were performed on the systems using all the different frequencies of each transducers (Madsen et al., 1995). Tests and measurements were performed using the GAMMEX RMI 403GS Precision Multipurpose Grey Scale Test phantom. Each periodic test gave six sets of image data, which consisted of approximately seven images per transducer for each operating frequency, viz., uniformity, horizontal and vertical caliper accuracy, depth of penetration, anechoic object observation and gray scale evaluation, axial and lateral resolutions. Thus, it amounts to a total of about 100 images in each set. The tests were performed by sonographers over a period 12 months. All the images were accessed using web-based program Medisurf. A database was prepared in Microsoft Excel to store all the information and data (test results and test settings) of each frequency transducer. Ultrasound Equipment and Transducers The ultrasound equipments used for image acquisition were three systems manufactured by Acuson, a Siemens Company (Mountain View, California) and three LOGIQ 700 systems manufactured by General Electric Medical Systems, Milwaukee, Wisconsin. Figures 2-1 and 2-2 are the images of Acuson and GE equipments used for this study.

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32 Figure 2-1. Acuson Figure 2-2. LOGIQ 700 Each system is a real-time imaging system capable of presenting information in both real-time imaging system capable of presenting information in both real-time and freeze frames. The various transducers used with each system are described in the Tables 2-1, 22 and shown in the Figures 2-3 and 2-4.

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33 Table 2-1. Acuson transducers ACUSON Transducer Model Frequencies of Operation (MHz) Application Description C3* 2.5, 3.5 General Purpose/ OB Gyn C7* 5, 7 OB Gyn /Pediatric/Small Adult EC7 3/5, 7 End Fire Endocavity L7EF 7/3, 10/5 Small Parts/ peripheral V4* 2.5, 3.5, 4 General Purpose V7 5, 6, 7 Targeted OB Gyn/ Fetal cardiac V714s 5, 7 Cardiovascular

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34 Table 2-2. LOGIQ 700 transducers GE LOGIQ 700 Transducer Model Frequencies of operation (MHz) Application Description 348C 2, 3, 4 Abdomen, Ob Gyn, Urology, Vascular 546LC 4, 6 Vascular, Small Parts 548C 4, 5, 7 Abdomen, Ob Gyn, Urology, Vascular 618E 5, 7 Neonatal, Pediatrics, Vascular LA39C 8, 9, 11, 12 Vascular, Small Parts, Neonatal, Pediatrics

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35 Description of the Phantom Figure 2-3. GAMMEX RMI 403GS phantom The phantom chosen for this study is GAMMEX RMI 403 GS manufactured by Radiation Measurements, Inc. Middleton, Wisconsin, and is shown in Figure 2-3. The phantom assembly is a patented, water-based soft-tissue equivalent gel. The scanning surface is 0.4 mm polyurethane backed with a polymer vapor barrier and the gel being more elastic than other materials and allows more pressure to be applied to the scanning surface without subsequent damage to the material. At normal or room temperatures, it accurately simulates the ultrasound characteristics of human liver tissue. The specific fabrication procedures enable close control over the homogeneity, and the reliability of acoustic characteristics of the phantom. The speed of sound in the phantom can be adjusted between 0.7 dB/cm/MHz and 0.50 dB/cm/MHz. (UserÂ’s Guide: GAMMEX RMI 403GS, 1996). The relation between the acoustic attenuation, A, and the acoustic frequency, F, is of the form A = AoFn with values of the power coefficient, n, in the range

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36 of 0.8 to 1.10, indicating the proportional increase of the acoustic attenuation with frequency. Backscatter characteristics can be adjusted through the addition of predetermined amounts of calibrated scatter material. The tissue mimicking material like most other phantom materials will desiccate if unprotected. It is therefore suggested to be stored properly at 35o – 105o F (2 – 40o C) (User’s Guide: GAMMEX RMI 403GS, 1996) as freezing temperatures can damage the test instrument and high temperatures will accelerate desiccation (Njeh, 1999). All resolution targets are made from microfilament nylon wire with a diameter of 0.1 mm. The phantom is encased in a rugged, shatterproof, extruded ABS plastic container with a thin film membrane and water dam to facilitate scanning. The phantom comes packaged in a foam lined, airtight carrying case and zipper sealed plastic bag to minimize desiccation and damage. The fact that the phantom consists of structures of known dimensions and exhibits predictable acoustic properties ensures that testing mechanisms are carried out with known, reproducible, and constant parameters (Rownd, 1997). A schematic of the Model 403 GS phantom is shown in the Figure 2-6. The phantom contains discrete, precision-spaced groups of nylon microfilament targets, as described above. (User’s Guide: GAMMEX RMI 403GS, 1996) Vertical Plane Target Group The vertical plane target group is useful for many different measurements. This target group assesses the depth of penetration, vertical distance accuracy, and focal zone of an imaging system. The target group consists of a group of 0.1 mm diameter parallel nylon wires positioned 2 cm apart, down the center of the phantom in a vertical plane.

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37 Horizontal Plane Target Groups This target group is used to determine the accuracy of measurements made perpendicular to the beam axis and is critical for the same reasons as vertical distance measurements above. The horizontal plane target consists of a group of 0.1 mm parallel wires positioned 3 cm apart in a horizontal plane at depths of 2 and 12 cm respectively. Axial Resolution Target Group The axial resolution target consists of five parallel, 0.1mm diameter wires horizontally placed 1mm apart and vertically placed at 0.25, 0.5, 1, 1.25 and 2mm apart from center to center, as shown in the figure 2-6. This target is designed to accurately assess axial resolution capabilities at depths of 3, 8 and 14 cm respectively. Lateral resolution can also be monitored using the same target group. Figure 2-4 Axial resolution target group 1mm 2.0mm 1.0 mm 0.5mm 0.25 mm

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38 Anechoic 6 dB + 6 dB + 12 dB 1 2 3 4 Gray Scale Targets The phantom section utilized for this gray scale evaluation and anechoic object perception test consists of a set of four spherical objects each having diameter 1cm, placed at depth of 6 cm with contrast varying from 0, -6, +6 and + 12 dB respectively, as seen in the Figure 2-5. Figure 2-5. Gray scale targets

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39 Figure 2-6. Schematic model of RMI 403GS Application of a coupling gel or water to the scanning surface of the phantom is necessary to fill the air gap between the transducer head and phantom surface. The difference in the acoustic impedance of air and the scanning surface would result in poor transmission of the ultrasound beam into the phantom. For testing procedures developed here, the coupling medium was chosen to be water.

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40 Medisurf MediSurf utilizes web-based approach for access of clinical image and data. MediSurf functions on the server-client relationship. MediSurf client (i.e., Department of Radiology, Shands at UF) works on PC platform and is able to contact the server using a standard Web browser, like Internet Explorer through the Internet. The server then provides with a small JAVA applet. The applet allows for clinical images and information to be accessed through the server, turning the user's computers into a remote access engine. Images are viewed in full diagnostic quality, using the DICOM-3 protocol. The user controls allow to window, zoom, pan, measure and annotate images. Cursor conferencing with other MediSurf clients regarding a case is also possible all through the JAVA applet. No special purpose hardware or application software was needed. An example of an image viewing window in Medisurf is shown in Figure 2-7.

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41 Figure 2-7. Medisurf image viewing Analysis Software: Analyze Analyze is a comprehensive and interactive package for multidimensional image visualization, processing and analysis developed by The Biomedical Imaging Resource Department at the Mayo Foundation. The Analyze software system is entirely built upon a toolkit of optimized functions that are organized into a software development library called AVW. Analyze is supported with an intuitive windows-based interface which made it easy to learn and to use. The most important feature of Analyze is that it allows multiple volume images to be simultaneously accessed and processed by multiple programs in a multi-window interface. The user interface for Analyze is based on Tcl/Tk,

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42 which offers full compliance with interface standards across multivendor workstations and PCs. Features: The User Interface The interface to each program is fully configurable, including image sizes, font styles, colors, automatic iconification of sub-windows, powerbar configuration, etc. All configurable interface features are user-specific and can be set interactively or through standard app-defaults (X-windows) resource mechanisms. A summary of features includes: Standardized, common interface widgets. Integration with standard tool (i.e., file box). Individual interface windows for specific parameter sets. Reconfigurable window sizes. Iconification for all window types. User-configurable power-bar with icons. Separate image display canvases for each program-specific display. Configurable image matrix. o Resizable with automatic scroll bar placement. o Automatic color resource allocation for best image display. Configurable program resources (e.g., fonts, colors) via standard resource definition files.

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43 Multiple Volume Sharing As mentioned earlier, Analyze allows the loading of and access to multiple volume images, object maps, text files, and other related file structures as independent entities that can be selected and used simultaneously within a given tool or with multiple tools. Volume images are represented as icons in the Analyze windows. The main Analyze canvas displays iconic representations of all loaded volume images, and each individual program window shows an iconic representation of the volume image currently assigned to that program. Volume image icons can be used to "drag-and-drop" between all Analyze modules, permitting full sharing of volume images amongst several processes and allowing the output of a given process to be shared as the input to another. Analyze Modules The following summarizes the advanced algorithms and major features of the Analyze software system that were utilized during the study. Analyze Main Control Panel The control panel window is shown in Figure 2-8. The figure shows all the menu options available in an Analyze main control panel. The features include:

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44 Figure 2-8. Analyze main control panel Launching pad for all Analyze programs, either from menus or power bar icons. Configurable, multiple power bar(s) for iconic representations of programs. Control canvas for loaded volume images with iconic representation of images. Configurable loaded volume location for multiple, independent sessions. System resource monitor (disk, memory, time, etc.) Powerbar editor and icon layout facility Support for multiple user preferences (interface options, etc.)

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45 Image Data Retrieval and Management Figure 2-9 Import-export window Import Export Figure 2-9 shows an export-import window in analyze. The import/export of standard image file formats and many commercial scanner formats is possible using Analyze. It also includes conversion to/from over 30 standard image formats, including the DICOM standard using high fidelity, rapid image compression/decompression wavelet applications.

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46 File Manager It also includes graphical file manager with iconic representation of images and other file types and is used for direct drag and drop to/from the Analyze file manager and other Analyze programs. Image Data Loading and Storing Load/Load As Save/Save As These options support for native image file formats without need for conversion. The volume image resizing is based on automated isotropic sampling (non-cubic resizing). In addition, it also offers interactive sub-regioning, flipping, and padding of volume image, data type conversion with intensity windowing or thresholding. Image Mensuration and Quantitative Analysis The features described below are seen in Figure 2-10. Line Profile Interactive plotting and measurement of line and trace profiles. Region Of Interest (ROI) Interactive definition of multiple regions of interest. Selection and automatic sampling of regions of interest. Measurement of dimensions and densities. Measurement of regional shape and texture. ASCII data file format for exporting to standard analysis programs. Tree Analysis Analysis of tree structures (lengths, branching angles, cross-sectional areas).

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47 Figure 2-10. Image mensuration

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48 Methodology: Description of Various Tests The RMI 403 GS Precision Multi-Purpose Gray Scale Test Phantom was used for all the test measurements. The tests were performed and the subjective tests were evaluated using Analyze. The QC tests, along with the individual phantom test sections and quantitative measurements performed using Analyze, are discussed below. Uniformity Ultrasound systems can generate various image artifacts and non-uniformities, which in some cases could mask variations in tissue texture. Common non-uniformities are either horizontal bands in the image, which are caused by inadequate handling of transitions between focal zones or vertical bands indicating inactive or damaged transducer. Uniformity is defined as the ability of the machine to display echoes of the same magnitude and depth with equal brightness on the display. This is a good test to ensure all crystals within the transducer are functioning similarly.

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49 Figure 2-11. Phantom section for uniformity The phantom section for this test, as seen in the Figure 2-11, is tissue-mimicking (TM) material of uniform texture similar to that of liver parenchyma, and is relatively free of filament and lesion-simulating targets. The conventional technique which is recommended by AIUM for assessing field uniformity is to assess that the gray level remains consistent with no banding in horizontal areas at each depth, with no apparent streaking or reverberation artifacts. If any artifacts are to be found then the test should be redone and if any persistent artifact occurs the service engineer is contacted. Uniformity is evaluated by performing Region of Interest (ROI) measurements. The tool was completely placed inside the image. The STD (standard deviation) and mean are measured corresponding to the echo level, and noise measurements, respectively. Similarly, ROIs of equal areas (since the first ROI is moved to all other specified locations of Ax1, Ax2, Lat 1 and Lat 2) were placed on all four sides along the central axis (horizontal and vertical), as depicted in the Figure 2-12. The same procedure was

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50 followed to make quantitative assessments. The results were then compared for generating periodic trends and performance was compared at different equipment settings. Figure 2-12. Ultrasound image of uniformity test showing the ROIs Depth of Penetration Depth of penetration is the greatest distance in a phantom for which echo signals from the scatterers within the tissue-mimicking background material can be detected on the display. The frequency of the transducer, the attenuation of the medium being imaged and the system settings determine the depth of penetration. The phantom section for this test is shown in the Figure 2-13. A uniform tissuemimicking section having an attenuation coefficient of 0.7-dB/ cm/ MHz. This section is

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51 several cm wider than the transducer and extends to a distance of about 18 cm. Consequently, depth of visualization can be analyzed for low as well as high frequency transducers. The section includes a column of high frequency target “depth markers” that are oriented perpendicular to the scan plane and a re located at 2 cm intervals. Figure 2-13. Phantom section for depth of penetration The point at which the usable tissue information disappears is a good indicator of maximum depth of visualization or penetration. (Goodsitt 1998; Goldstein 1998) The distance was carefully measured as indicated in Figure 2-14. The results were then compared for generating periodic trends and performance was compared at different equipment settings and frequencies.

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52 Figure 2-14. Ultrasound image showing the depth of penetration measurement Spatial Distance Fidelity: Distance accuracies, both in the direction of the ultrasound beam and perpendicular to the ultrasound beam are contributors to total image quality and are therefore indications of scanner performance. Improper distance measurements result in positioning of imaged structures being indicated at improper locations. Vertical Distance Accuracy Vertical distance is defined as the distance along the axis of the beam. Distances are used to measure areas, volumes, depths and size of objects. Accurate measurements are therefore necessary to ensure proper diagnosis. The vertical plane target allows one to assess the accuracy of vertical measurements.

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53 Figure 2-15. Phantom section for vertical distance accuracy The phantom section for this test is shown in Figure 2-15. The highlighted section indicates the vertical distance targets group, which includes a vertical column of filament targets that are oriented perpendicular to the scan plane and are located at 2 cm intervals. The distance between the most clearly separated filament targets in the vertical column displayed in the image was measured, as shown in Figure 2-16. The results were then compared for generating periodic trends and performance was compared at different equipment settings and frequencies.

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54 Figure 2-16. Ultrasound image of vertical distance accuracy measurement Horizontal Distance Accuracy The horizontal test assesses the accuracy of the measurements perpendicular to the beam axis. Horizontal distance errors can be the result of the flaws in the transducer scan mechanism, and thus are particularly important for mechanical real-time transducers, including annular arrays.

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55 Figure 2-17. Phantom section for horizontal distance accuracy The phantom section for this test is shown as the highlighted section in Figure 2-17 and it includes horizontal rows of filament targets separated by 3 cm. The distance between the most clearly separated filament targets in the horizontal column displayed in the image was measured using the ultrasound instrumentÂ’s calipers to measure the distance, as shown in the Figure 2-18.

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56 Figure 2-18. Ultrasound image showing horizontal distance accuracy measurement The results were then compared for generating periodic trends and performance was compared at different equipment settings and frequency. Spatial Resolution: Axial And Lateral The axial resolution is defined as the ability of an ultrasound system to resolve objects in close proximity along the axis of the sound beam. Axial resolution is proportional to the length of the systemÂ’s transmitted pulse or pulse length. The pulse length is the product of the pulse duration and the speed of sound in tissue. Axial resolution, by physical principles, can be no greater than one-half the pulse length. In other words, two objects located along the axis of the ultrasound beam will be registered as two separate structures only if their separation distance exceeds one half the pulse-length. Separation

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57 by less than one-half of the pulse length results in overlapping of return echoes and no spatial distinction can be made, thereby resulting in a single pulse registration. Pulse lengths may be minimized by damping the transducer with an acoustically absorbent material to reduce ringing effects. Lateral resolution is similar to axial resolution except it is defined in the direction perpendicular to the beam axis. Lateral resolution is determined by the width of the ultrasound beam and therefore varies as a function of depth in tissue. Therefore, within the focal zone, the lateral resolution is detected to be at its best. The phantom section as drawn in the Figure 2-19, has three sets of axial resolution target group designed to accurately assess axial resolution capabilities at depths of 3, 8 and 13 cm, respectively. The target consists of four, 0.1 mm diameter wires vertically spaced at 2, 1, 0.5 and 0.25 mm and horizontally spaced at 1mm, respectively.

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58 Both axial and lateral resolutions were evaluated using the same target group. Figure 2-19. Phantom section for axial and lateral resolution targets Using the distance measurement tool, the length along the axis, and perpendicular to the axis of the ultrasound beam of a single pin of the axial resolution group was measured to evaluate the axial and lateral resolution, respectively, which is shown very clearly in Figure 2-20. The results were then compared for generating periodic trends and performance was compared at different equipment settings and frequency.

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59 Figure 2-20. Ultrasound images showing axial and lateral resolution measurements

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60 Anechoic Object Imaging and Gray Scale Evaluation The tests for anechoic object perception and gray scale evaluation are combined in the same procedure. The anechoic object /cyst imaging test examines the systemÂ’s ability to detect and accurately display round, negative contrast objects of various sizes. This test combines aspects of spatial and contrast resolution and image uniformity into a single test (Metcalfe SC, Evans JA, 1992). Electrical noise, side lobes and problems in the image processing hardware are the factors that affect anechoic object image quality. Figure 2-21. Phantom section for anechoic image perception and gray scale evaluation The phantom section utilized for this test consists of a set of four spherical objects each having diameter 1cm, placed at depth of 6 cm with contrast varying from 0, -6, +6 and + 12 dB, respectively, as shown in the highlighted portion of the Figure 2-21 Using the distance measurement tool of ANALYZE, the height and width of the anechoic object (0dB) was measured and the ratio of the height divided by width was recorded. The qualitative assessment is performed by grading the quality of images of

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61 objects as c = clear, f = filled in, j = jagged edge, N = no enhancement distal to the anechoic object. For the quantitative measurement the pixel values were computed using the ROI tool (std. deviation and mean) of the ANALYZE software. The example of such a measurement is shown in the Figure 2-22. Figure 2-22. Ultrasound image showing ROIs for anechoic object perception and gray scale test. The qualitative measurement ensures that the gray levels are displayed on the monitor consistently. The quantitative measurement ensures that gray level signal is measured consistently. By performing these tests, the user can determine the optimal system control settings for measuring gray levels, which is described in the following discussion. These settings can then be used in clinical applications.

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62 System Linearity Ultrasound systems use special processing circuits to translate the amplitude of echoes into brightness levels on the video monitor. These circuits use mathematical functions that often produce an S-shaped curve when graphed. As shown in the Figure 2-23 below, each echo level produces a corresponding brightness level on the monitor. Monitor Brightness level B+ Bo B-XdB 0dB +XdB Echo Level Figure 2-23. S-shaped curve translates echo level into brightness levels on the video display As long as the shape of the curve remains constant the contrast or difference in brightness, between different echo levels will remain constant. If the shape of the S-curve changes, the relative image brightness for each echo level will also change. For example, “image post-processing ” techniques help the user identify subtle tissue variations by modifying the shape of the S-curve to emphasize certain ranges of echo levels. Degradation of the system hardware can also affect the shape of the curve and produce unexpected variations in the contrast between the echo levels. This distortion in the

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63 information displayed to the user may affect the interpretation of the ultrasound image. An example of these distortions is shown below in the Figure 2-24. Monitor Brightness level B+’ B+ Bo Bo‘ BB-‘ -XdB 0dB +XdB Echo Level Figure 2-24. Changes in the shape of the S-curve result in different brightness levels for the same echo levels Changes in the system response can be identified by measuring the relative pixel value of the gray scale target to the background material as displayed on the monitor.2

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64 CHAPTER 3 RESULTS Initial Image Assessment The data obtained from the six ultrasound systems over a twelve-month time period are presented in this chapter. These data sets were evaluated for various trends corresponding to parameters such as time, gain, frequency, and output power etc. The tests that were primarily subjective were compared with AIUM standards followed by designing quantitative methods using Analyze software, for the same. The quantitative results were then compiled together and periodic trends were generated to study the behavior and the pattern of tests. The data are intended to demonstrate the type of information obtained using this methodology. Only selected data for each test are presented as it was difficult to show the results for each equipment in this section. They are, however included in Appendix C. Depth of Penetration The results for the depth of penetration were recorded by the operator, using the electronic calipers, at the time of the examination. All the results were evaluated using Analyze and periodic trends were generated. Table 3-1 shows a sample data for depth of penetration measurements. The sample data is for the SUFAcII equipment and all the transducers were assessed for all the frequencies of operation. The same data has been plotted in the Figure 3-1.

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65 Depth of penetration for SUFACII 0 2 4 6 8 10 12 14 16 18 Phase IPhase IIPhase IIIPhase IVTimeImaging depth in cm SUFAcII(C7*@5) SUFAcII(C7*@7) SUFAcII(L7EF@7/3) SUFAcII(L7EF@10/5) SUFAcII(V4*@2.5) SUFAcII(V4*@3.5) SUFAcII(v4*@4) SUFAcII(V714S@5) SUFAcII ( V714S@7 ) Table 3-1. Sample data for depth of penetration TRANSDUCER Phase I Phase II Phase III Phase IV SUFAcII(C7*@5) 10.0310 10.5 12.14 SUFAcII(C7*@7) 8.158.22 8.6 8.11 SUFAcII(L7EF@7/3) 7.837.83 7.77 7.81 SUFAcII(L7EF@10/5) 7.86.85 7.77 7.83 SUFAcII(V4*@2.5) 16.0816.2 16 16.19 SUFAcII(V4*@3.5) 16.0815.26 16.1 15.19 SUFAcII(v4*@4) 16.0216.1 16.1 14.23 SUFAcII(V714S@5) 9.259.26 9.17 9.3 SUFAcII(V714S@7) 5.836.85 6.17 5.32 Figure 3-1. Graphical representation of data in Table 3-1 Spatial Distance Fidelity: Horizontal and Vertical Caliper Accuracy The results for the horizontal and vertical caliper accuracy were recorded at the time of the examination and were measured again using Analyze. All the transducers were evaluated and periodic trends were generated. The results are assessed by comparing the measured distance between the selected filament targets in the phantom with the known distance. As seen in the Table 3-2 and 3-3, the measurements were made at two depths. The s column indicates measurements at shallow depths and d column indicates measurements closer to the maximum imaging depth.

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66 Table 3-2. Sample data for vertical distance accuracies (in cm) TRANSDUCER Phase I Phase II Phase III Phase IV s d s d s d s d SUFAcII(C7*@5) 2.02 2.02 2 1.99 2.02 2.01 1.99 2.02 SUFAcII(C7*@7) 2.01 2.01 2.02 2.01 2.01 2.01 1.98 1.99 SUFAcII(L7EF@7/3) 2.01 2.01 2.01 2.01 2.01 2.01 2.01 2 SUFAcII(L7EF@10/5) 2.01 2.01 2.01 2.01 2.01 2.01 2 2.02 SUFAcII(V4*@2.5) 2 1.99 2.01 2.02 1.99 2.01 2 1.99 SUFAcII(V4*@3.5) 2.02 1.99 2 1.99 1.99 1.99 2.01 2.01 SUFAcII(v4*@4) 2.01 1.99 2 1.99 1.99 1.99 1.99 1.99 SUFAcII(V714S@5) 2.01 2.01 2.01 2.02 2.01 2.01 2.01 2.01 SUFAcII(V714S@7) 2.01 2.02 2.01 2 2 2.01 2.01 2.01 Table 3-3. Sample data for horizontal distance accuracies (in cm) TRANSDUCER Phase I Phase II Phase III Phase IV s d s d s d s d SUFAcII(C7*@5) 2.98 2.992.99 2.99 3.01 3.04 3 3.02 SUFAcII(C7*@7) 2.99 2.983.01 2.99 3.01 2.83 2.99 2.99 SUFAcII(L7EF@7/3) 3.01 3.012.99 3.01 2.99 3.05 3.01 3.01 SUFAcII(L7EF@10/5) 3.01 3.013.01 2.99 3.01 3.01 3.01 3.01 SUFAcII(V4*@2.5) 3.01 2.903.01 2.99 3.01 2.96 3.01 2.99 SUFAcII(V4*@3.5) 3.01 2.983.01 3.02 3 3.16 3.01 3.01 SUFAcII(v4*@4) 3.01 2.993 2.99 3.01 3.01 3.01 3.01 SUFAcII(V714S@5) 3.01 3.012.99 2.99 3.01 3.05 2.98 2.98 SUFAcII(V714S@7) 3.01 3.013.01 3.01 3.02 3.02 3.01 3 Image Uniformity After the qualitative assessment as described earlier in chapter 2, quantitative assessment was accomplished using Analyze. The signal properties of the five different but equal area ROIs were evaluated. The periodic trends were generated using this quantitative data set. The data set for SUFAcII is shown here as an example in the figure 3-4. The Ax1 (top) and Ax2 (bottom) column suggest standard deviation (STD) values of the ROIs selected in the direction of the ultrasound beam and Lat1 (left) and Lat2 (right) indicated the values of the STD measured for ROIs selected laterally along the central region of the scan. The C column indicates the values for central ROI. The average value was then

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67 calculated in both axial and lateral directions and the results were compared. An average value was then recorded for axial and lateral measurements. Table 3-4. Sample data for uniformity measurements TRANSDUCER Phase I Phase II Ax1 Ax2 C Lat 1 Lat 2 Ax1 Ax2 C Lat 1 Lat 2 SUFAcII(C7*@5) 15.69 11.58 21.72 18.61 24.89 15.34 13.87 17.32 19.59 17.53 SUFAcII(C7*@7) 17.09 13.54 19.33 17.41 17.9 15.48 13.01 19.32 17.71 19.17 SUFAcII(L7EF@7/3) 19.88 18.18 18.6 19.06 17.59 19.2 18.26 20.86 18.36 20.07 SUFAcII(L7EF@10/5) 19.19 15.5 17.39 19.01 19.74 20.59 15.74 17.87 19.18 18.41 SUFAcII(V4*@2.5) 18.42 22.4 23.46 18.85 21.26 18.41 15.52 18.38 13.18 20.13 SUFAcII(V4*@3.5) 16.22 18.56 23.35 16.21 24 14.99 19.08 18.84 20.29 15.29 SUFAcII(v4*@4) 16.8 16.79 23.98 16.23 18.1 14.68 14.43 17.85 12.94 18.02 SUFAcII(V714S@5) 19.91 20.62 21.45 19.99 21.41 19.51 20.38 20.88 22.05 18.51 SUFAcII(V714S@7) 20.14 14.38 21.4 20.14 19.71 20.22 18.37 19.85 20.88 20.89 TRANSDUCER Phase III Phase IV Ax1 Ax2 C Lat 1 Lat 2 Ax1 Ax2 C Lat 1 Lat 2 SUFAcII(C7*@5) 15.31 10.81 16.37 16.42 19.43 14.5 13.96 18.73 17.74 19.47 SUFAcII(C7*@7) 13.11 10.76 15.99 18.63 20.15 16.06 13.52 15.72 16.28 20.72 SUFAcII(L7EF@7/3) 23.77 20.46 22.71 19.11 20.57 20.69 19.59 19.27 20.15 22.63 SUFAcII(L7EF@10/5) 23.73 15.57 19.06 20.91 20.07 19.4 14.41 18.04 20.63 20.2 SUFAcII(V4*@2.5) 18.18 19.57 17.63 13.5 17.23 10.98 11.7 13.61 12.68 11.38 SUFAcII(V4*@3.5) 14.69 21.03 16.92 13.18 12.62 15.25 15.43 19.43 16.87 12.76 SUFAcII(v4*@4) 13.89 18.14 18.12 11.58 14.2 13.84 14.05 19.15 17.01 14.28 SUFAcII(V714S@5) 19.09 13.05 23.45 20.54 23.2 20.82 17.24 23.73 20.87 20.99 SUFAcII(V714S@7) 17.53 12.38 22.91 21.53 20.85 22.8 21.15 22.46 20.6 20.93

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68 Table 3-5. Sample data for uniformity measurements after taking the average of axial and lateral measurements. TRANSDUCER Phase I Phase II Ax C Lat Ax C Lat SUFAcII(C7*@5) 13.64 21.72 21.75 14.61 17.32 18.56 SUFAcII(C7*@7) 15.32 19.33 17.66 14.25 19.32 18.44 SUFAcII(L7EF@7/3) 19.03 18.6 18.33 18.73 20.86 19.22 SUFAcII(L7EF@10/5) 17.35 17.39 19.38 18.17 17.87 18.8 SUFAcII(V4*@2.5) 20.41 23.46 20.06 16.97 18.38 16.66 SUFAcII(V4*@3.5) 17.39 23.35 20.11 17.04 18.84 17.79 SUFAcII(v4*@4) 16.80 23.98 17.17 14.56 17.85 15.48 SUFAcII(V714S@5) 20.27 21.45 20.7 19.95 20.88 20.28 SUFAcII(V714S@7) 17.26 21.4 19.93 19.30 19.85 20.89 TRANSDUCER Phase III Phase IV Ax C Lat Ax C Lat SUFAcII(C7*@5) 13.06 16.37 17.93 14.23 18.7 18.6 SUFAcII(C7*@7) 11.94 15.99 19.39 14.79 15.7 18.5 SUFAcII(L7EF@7/3) 22.12 22.71 19.84 20.14 19.3 21.4 SUFAcII(L7EF@10/5) 19.65 19.06 20.49 16.91 18 20.4 SUFAcII(V4*@2.5) 18.88 17.63 15.37 11.34 13.6 12 SUFAcII(V4*@3.5) 17.86 16.92 12.9 15.34 19.4 14.8 SUFAcII(v4*@4) 16.02 18.12 12.89 13.95 19.2 15.6 SUFAcII(V714S@5) 16.07 23.45 21.87 19.03 23.7 20.9 SUFAcII(V714S@7) 14.96 22.91 21.19 21.98 22.5 20.8

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69 Uniformity measurement (axially) 0.00 5.00 10.00 15.00 20.00 25.00 Phase IPhase IIPhase IIPhase IV TimeMeasurement SUFAcII(C7*@5) SUFAcII(C7*@7) SUFAcII(L7EF@7/3) SUFAcII(L7EF@10/5) SUFAcII(V4*@2.5) SUFAcII(V4*@3.5) SUFAcII(v4*@4) SUFAcII(V714S@5) SUFAcII ( V714S@7 ) Uniformity measurement (centre) 0 5 10 15 20 25 30 Phase IPhase IIPhase IIPhase IV TimeMeasurement SUFAcII(C7*@5) SUFAcII(C7*@7) SUFAcII(L7EF@7/3) SUFAcII(L7EF@10/5) SUFAcII(V4*@2.5) SUFAcII(V4*@3.5) SUFAcII(v4*@4) SUFAcII(V714S@5) SUFAcII ( V714S@7 ) Uniformity measurement (laterally) 0 5 10 15 20 25 Phase IPhase IIPhase IIPhase IV TimeMeasurement SUFAcII(C7*@5) SUFAcII(C7*@7) SUFAcII(L7EF@7/3) SUFAcII(L7EF@10/5) SUFAcII(V4*@2.5) SUFAcII(V4*@3.5) SUFAcII(v4*@4) SUFAcII(V714S@5) SUFAcII ( V714S@7 ) Figure 3-2. Graphical representations of data in Table 3-5

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70 Anechoic Object Perception/ Gray Level Measurement After the qualitative assessment, quantitative assessment was accomplished using Analyze. The signal properties of all the four different objects were evaluated. The object 1, 2, 3 and 4 indicate the objects having contrast of +12, -6, +6 and 0 dB respectively. The ROI was selected to fit all the four objects very carefully. The pixel values were then measured for each ROI. The pixel value of the background was also measured. The values for each object relative to this back ground value were the calculated. The relative values were then plotted to check the S-curve. Table 3-6 shows the relative values for SUFAcII. The S curve is plotted for data in chart 3-3 for Phase 1 Table 3-6. Sample data for gray scale evaluations TRANSDUCER Phase I Phase II Obj. 1 Obj. 2 Obj. 3 Obj. 4 Obj. 1 Obj. 2 Obj. 3 Obj. 4 SUFAcII(C7*@5) 6.97 5.93 3.65 1.13 8.72 6.99 4.34 1.71 SUFAcII(C7*@7) 8.55 7.36 4.88 1.88 6.91 6.82 4.43 1.55 SUFAcII(L7EF@7/3) 5.99 4.50 2.97 1.08 6.77 5.42 2.98 1.28 SUFAcII(L7EF@10/5) 6.44 4.79 3.09 1.09 7.63 6.16 3.04 1.26 SUFAcII(V4*@2.5) 7.66 5.67 3.56 1.54 7.20 5.22 3.14 1.54 SUFAcII(V4*@3.5) 8.53 6.56 4.32 1.42 8.09 6.08 4.08 1.72 SUFAcII(v4*@4) 7.89 6.20 4.24 1.59 9.14 7.02 3.84 1.42 SUFAcII(V714S@5) 6.41 5.05 3.20 1.33 7.66 5.61 3.17 1.62 SUFAcII(V714S@7) 6.34 5.17 3.04 1.13 7.50 6.21 3.70 1.38 TRANSDUCER Phase I Phase II Obj. 1 Obj. 2 Obj. 3 Obj. 4 Obj. 1 Obj. 2 Obj. 3 Obj. 4 SUFAcII(C7*@5) 7.95 6.79 2.00 1.33 7.15 6.55 3.97 1.40 SUFAcII(C7*@7) 8.15 7.40 4.31 1.44 8.25 8.44 5.34 1.46 SUFAcII(L7EF@7/3) 5.74 0.79 2.38 1.08 7.10 0.57 2.61 1.17 SUFAcII(L7EF@10/5) 7.69 5.31 3.19 1.69 7.22 5.57 2.66 1.20 SUFAcII(V4*@2.5) 5.97 4.57 2.55 1.73 9.31 7.24 4.22 1.90 SUFAcII(V4*@3.5) 7.30 5.24 2.91 1.53 7.23 5.33 3.22 1.31 SUFAcII(v4*@4) 6.64 4.99 2.68 1.28 7.12 5.52 3.02 1.26 SUFAcII(V714S@5) 5.60 4.75 2.63 0.91 6.18 4.77 2.68 1.33 SUFAcII(V714S@7) 5.61 5.05 3.07 0.94 6.90 6.22 3.26 1.50

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71 Figure 3-3. S-curve for phase I Spatial Resolution: Axial Resolution And Lateral Resolution Axial resolution The axial resolution was first evaluated at all depths but was found fairly constant at all depths. Hence, it was concluded that axial resolution of the equipment using a particular transducer can be successfully evaluated at a single depth. Table 3-6 lists the sample data for SUFAcII for axial resolution measurements. It was observed that the axial resolution improved greatly with increasing frequency, as expected. The quantitative method is more accurate and also eliminates the discrepancies that might result using the conventional method of using target pair spacing in phantom, since the target pair spacing in phantoms are inadequate and permit the user to do no more than draw gross conclusions about axial resolution. S-curve for SUFAcII for Phase I 0 2 4 6 8 10 -10-5051015 d B Bri g htness Value SUFAcII(C7*@5) SUFAcII(C7*@7) SUFAcII(L7EF@ 7/3) SUFAcII(L7EF@ 10/5) SUFAcII(V4*@2.5) SUFAcII(V4*@3.5) SUFAcII(v4*@ 4) SUFAcII(V714S@5) SUFAcII(V714S@7)

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72 Table 3-7. Sample data for axial resolution measurements TRANSDUCER Phase I Phase II Phase III Phase IV SUFAcII(C7*@5) 2 2 2 1.5 SUFAcII(C7*@7) 2 1 1 1 SUFAcII(L7EF@7/3) 1.5 1.5 2 2 SUFAcII(L7EF@10/5) 1 1 1 1 SUFAcII(V4*@2.5) 2 1.5 0 1.5 SUFAcII(V4*@3.5) 1 1 0.5 0.5 SUFAcII(v4*@4) 1 0.5 0.5 0.5 SUFAcII(V714S@5) 1.5 1.5 1.5 2 SUFAcII(V714S@7) 1.5 1.5 2 2 Figure 3-4. Graphical representation for Table 3-7 Lateral Resolution The lateral resolution is measured at all three depths using the axial resolution target group and the example of lateral resolution data set can be seen in the Table 3-8, the s , m and d stand for shallow, medium, and deep depth ranges. As expected, the lateral resolution improves with depth. Axial Resolution for SUFAcII 0 0.5 1 1.5 2 2.5 3 3.5 Phase IPhase IIPhase IIIPhase IV TimeAxial resolution in cm SUFAcII(C7*@5) SUFAcII(C7*@7) SUFAcII(L7EF@7/3) SUFAcII(L7EF@10/5) SUFAcII(V4*@2.5) SUFAcII(V4*@3.5) SUFAcII(v4*@4) SUFAcII(V714S@5) SUFAcII(V714S@7)

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73 Table 3-8. Sample data for lateral resolution measurements TRANSDUCER Phase I Phase II Phase III Phase IV s m d s m d S m d s m d SUFAcII(C7*@5) 3 5 5 3 5 0 2 3 0 SUFAcII(C7*@7) 3 3 0 3 5 0 2 3 0 2 3 0 SUFAcII(L7EF@7/3) 3 4 5 2 3 5 2 4 5 2 3 4 SUFAcII(L7EF@10/5) 3 3.5 4 2 2 4 2 5 4 2 3 3 SUFAcII(V4*@2.5) 2 3 5 2 4 6 0 0 4 1 3 4 SUFAcII(V4*@3.5) 2 3 4 1 2 1 3 4 1 4 3 SUFAcII(v4*@4) 1 4 3 1 3 4 1 2 3 SUFAcII(V714S@5) 2 3 3 2 3 4 2 4 4 3 5 7 SUFAcII(V714S@7) 2 333 3 3354 3 5 5

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74 Figure 3-5. Graphical representation of data in Table 3-8 Lateral Resolution (for shallow depth) for SUFAcII0 0.5 1 1.5 2 2.5 3 3.5 Phase IPhase IIPhase IIIPhase IV Time SUFAcII(C7*@5) SUFAcII(C7*@7) SUFAcII(L7EF@7/3) SUFAcII(L7EF@10/5) SUFAcII(V4*@2.5) SUFAcII(V4*@3.5) SUFAcII(v4*@4) SUFAcII(V714S@5) SUFAcII(V714S@7) Lateral Resolution in cm Lateral Resolution (for medium depth) for SUFAcII 0 1 2 3 4 5 6 Phase IPhase IIPhase IIIPhase IV TimeLateral Resolution in cm SUFAcII(C7*@5) SUFAcII(C7*@7) SUFAcII(L7EF@7/3) SUFAcII(L7EF@10/5) SUFAcII(V4*@2.5) SUFAcII(V4*@3.5) SUFAcII(v4*@4) SUFAcII(V714S@5) SUFAcII(V714S@7) Lateral Resolution (for deep depths) for SUFAcII 0 1 2 3 4 5 6 7 8 Phase IPhase IIPhase IIIPhase IV TimeLateral Resolution in cm SUFAcII(C7*@5) SUFAcII(C7*@7) SUFAcII(L7EF@7/3) SUFAcII(L7EF@10/5) SUFAcII(V4*@2.5) SUFAcII(V4*@3.5) SUFAcII(v4*@4) SUFAcII(V714S@5) SUFAcII(V714S@7)

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75 CHAPTER 4 DISCUSSION The phantom measurements were condensed to give data sets that were then distributed over four phases with a year of timeline reference. These data sets were then evaluated for various trends corresponding to factors such as time, gain, frequency, and output power etc. The tests with operator-recorded values were studied first and periodic trends were generated and evaluated. The tests that were primarily subjective were evaluated with AIUM standards as reference followed by designing quantitative methods using Analyze software, for the same. The quantitative results were then compiled together and periodic trends were generated to study the behavior and the pattern of tests. Depending upon the performance of the transducer and the behavior of each QC trend with respect to the parameter variations, a distinct set of action levels and defect levels were formulated. Uniformity The results of the field uniformity measurements using all the six scanners over a 12month period were compared and periodic trends were generated. The equipments indicate variability in the field uniformity during this period, with the range of standard deviations extending from 10.0 to 25.0, which would is evident in the Table 3-5. Field uniformity measurements for the axial and lateral direction were substantially the same. Visual inspection of field uniformity for regions outside the ROI indicated no obvious anomalies. Also, the test was found to be highly sensitive to gain and power settings, so it was concluded that the settings used for the baseline testing should be strictly followed

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76 for this test. It was experienced that performing the image uniformity with a quantitative approach decreases the risk of false negatives. The observed variability in field uniformity measurements may be attributed to the fine-tuning of TGC controls by the operator or to fluctuations in the electronic circuitry of the equipment. Depth of Penetration The results of the field uniformity measurements using all the six scanners over a 12month period were compared and periodic trends were generated. The imaging depth measurements remained the same and did not change substantially over that time period, as seen form the Table 3-1 and Figure 3-1. Quantitative assessment of the data suggested that the depth of visualization is limited by the frequency of the transducer, as expected. The trends showed that if same settings (i.e. output power, gain, TGC and focal depth) are used, then the depth of visualization remains fairly constant over time and turns out to be the most reliable test to check the sensitivity of the US equipment. Table 4-1 gives the acceptable estimated depth ranges for corresponding frequencies.

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77 Table 4-1. Estimated depths for frequencies NOMINAL FREQUENCY (MHz) ACCEPTABLE ESTIMATED DEPTH RANGE (cm) 3 18.0 – 22.0 4 13.5 – 16.5 5 10.8 – 13.2 6 9.0 – 11.0 7 7.7 – 9.4 8 6.8 – 8.3 9 6.0 – 7.3 10 5.4 – 6.6 Distance Accuracies: Horizontal and Vertical distance accuracies The horizontal and vertical distance accuracies are assessed for both shallow and deep ranges. The vertical distance targets as discussed earlier in Chapter 2, are separated form each other by a distance of 2 mm. So as seen in the table 3-2 the results look very good and the error percentile is not more than 1 %. Similarly, the distance of separation between horizontal targets is 3mm and Table 3-3 suggests that the measurements go well with distance of separation distance. The quantitative assessment of the test results suggested that the distance accuracy test is one of the most important tests of the QC program and should be the first test on the QC list since there would be subsequent tests that would utilize electronic calipers for distance measurements and the errors will not always be very obvious. The vertical distance accuracy test was proved to be a good technique to investigate drift and/or failure in the internal timing circuit of the system since the horizontal caliper measurements seem to be less affected by it. However, horizontal distance accuracy measurement was proved to be effective in assessing transducer flaws (especially mechanical real-time transducers, including annular arrays) such as motor wear, which can distort accuracy.

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78 Distance accuracies, both in the horizontal and vertical directions, were assessed. Many diagnostic ultrasound exams are performed that mandate a high degree of accuracy in distance measurements for the horizontal direction exceeds those for the vertical direction. Anechoic Object Perception and Gray Level Measurement For the anechoic object perception tests the ratio of diameter measured along horizontal and vertical axis of the object was <2 for all cases indicating that the anechoic object was consistent and uniform with well-defined edge. The echo values were found in the following range: Table 4-2. Echo level measurements Object Echo Level Range Object 1 100-200 Object 2 50-150 Object 3 30-100 Object 4 10-75 For the gray level measurement the relative echo values with reference to the background were evaluated and checked for consistency. It was found that with a constant setup of dynamic range, the results are fairly reproducible. Gray scale evaluation in an ultrasonic imaging system is a competitive performance specification indicating the effects of the dynamic range and system noise. These measurements are also important for comparison with competitive vendors and for ensuring that like equipment from the same vendor operates in a consistent fashion.

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79 Spatial Resolution: Axial and Lateral Resolution Axial resolution measurements were found to decrease with increasing target spacing and were independent of the depth of the target groupings in the phantom. This is consistent with what one would expect, considering the physical properties that determine the axial resolution of the system. Variation in resolution as a function of transducer frequency is also evident, with highest transducer exhibiting the greatest resolution sensitivity. Lateral resolution, which is limited by the beam width of the transducer, is expected to vary according to the spreading of the ultrasound beam for each transducer. The results indicate that both consistent and quantifiable measurements can be obtained with these tests Recommendations The QC program developed with the aid of this research should be followed up every three months to make the results are routine and reproducible. Also, the slice thickness measurement test, which would require an appropriate test measurement phantom, should be incorporated in the program (Goldstein 1988) in the coming year after successful implementation of current QC program. The protocol is listed in the QC Excel Program Workbook, which can be found in Appendix B After one year of successful implementation and follow-up the facility should apply for the process of accreditations from AIUM and ACR. The QC program developed in this study is designed taking care that it satisfies criteria for the application for accreditation of the ultrasound equipments in the facility. With purchase of a new ultrasound equipment the first QC implementation should automatically be taken a s the baseline values for all tests.

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80 CHAPTER 5 CONCLUSION The purpose of this research was to establish an objective criterion for measurements of routine parameters of image quality in diagnostic ultrasound. With the establishment of such procedures, it is possible to monitor the performance of ultrasound equipments on a periodic basis to evaluate their operation both with respect to other scanners and with their own performance over time. The data obtained using this methodology indicate that the above stated objectives have been achieved. The image analysis protocol described in appendix–a was developed in this program using the understanding of the test performances of theses equipments as discussed in Chapter 4. Also, an automatic excel program appendix-b developed using the recommended action levels discussed in Table 5-1 is designed so that it can be used as a QC tool for quantitative evaluation and automatic performance testing. The excel program also includes Slice thickness measurements (Goldstein 1988) and PACS QC section by which the evaluation of monitor becomes possible. Quality Control: Tolerance Levels Due to the diverse range of ultrasound equipment available, only a few standards have been established in the field of medical diagnostic ultrasound. It is therefore left up to the owners and operators of the ultrasound scanners themselves to determine acceptable limits of variability in test results. The frequency at which each test is to be conducted must also be determined by the user.

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81 Although the determination of measurement acceptability is ultimately the decision of the users themselves, tolerable limits have been suggested and published to serve as a guide from monitoring various image parameters. The department housing the scanner can determine performance standards based upon the level of performance standards based upon the level of performance at the time of purchase and on manufacturer stated operating capabilities. The clinical needs of the department may also serve as the operational criteria. The frequency at which particular tests are performed can be based upon the variability encountered in control measurements. Suggested levels of tolerance, which can be used as guidelines, for successful evaluation of the QC program are listed in Table 5-1. Selection of Action Levels The action level is used as an indicator of the image quality indicator value at which corrective action would be taken. Action levels are chosen in such a way that they are located well within the instrumentÂ’s specified tolerances. This is implemented to ensure that the image quality indicators would never actually refer defect levels. + Tolerance Upper Action Level Normal operating range Tolerance Lower Action Level Action Levels are placed inside the tolerance limits to ensure that corrective action occurs before defective quality levels are reached.

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82 It was observed that a value somewhere between one-half and three quarters of the tolerance works well for most action levels. Recommended action levels are provided on each QC data sheet. Image Uniformity For this particular study, scanner control settings must be established such that the standard deviation of the ROI used for measuring the uniformity would be as low as possible while still producing a clinically relevant image. Variations in the standard deviation from machine to machine and of one machine over a time period are therefore of significance here. It is suggested that the test be performed at least monthly. Such a frequency can ensure that any damage to the transducer elements, such as from dropping or mishandling may be detected before the faulty transducer is used excessively. Depth of Penetration Quantitative assessment of the data suggested that the maximum depth of visualization is limited by the frequency of the transducer, as expected. It is required that maximum depth of visualization remains constant over time. Therefore, it is suggested that the test should be repeated with adjustments in dynamic range and TGC parameter values if the depth of visualization measured on the monitor varies from its baseline value by more than 0.6 cm. If the change is more than 1 cm the service engineer should be contacted since higher variations indicated salient performance degradation. This test is also recommended to be performed quarterly like all other tests.

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83 Horizontal and Vertical Caliper Accuracy Distances between calipers located along the direction of the ultrasound beam (vertical calipers) should agree with the actual distance within +/1.5 mm or 1.5%. If the variation is more than +/2 mm or 2% service engineer must be contacted. Distances between the calipers located perpendicular to the central axis of the ultrasound beam are, as discussed earlier, usually less accurate than vertical measurements. Distances here should correspond to actual distances within +/2 mm or +/2 %. If the variation is more than +/3 mm or 3 % service engineer must be contacted. These tests should also be performed quarterly and should be first test on the QC list since subsequent tests that utilizes caliper measurements would give ambiguous readings if their was a problem detected with the accuracy of the calipers. Anechoic Object Perception and Gray Level Measurement The gray level measurements and tolerance have not been addressed with regard to the type of quantitative measurements described in this methodology. The information obtained is therefore useful to the department as a consistency of operation check and hence should be second test on the QC Program. Because contrast sensitivity is dependant upon the amount of noise in the system and on the dynamic range chosen by the operator, the monitoring of measured ROI evaluations will provide information about changes in the noise levels as well as advisability of an optimal choice of dynamic range for a particular procedure. The S-curve should remain more or less consistent with the baseline S-curve to indicate sound gray scale range.

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84 Axial Resolution Axial resolution capabilities vary with the frequency of the transducer and very little with the depth of the objects to be extinguished. Axial resolution measurements are usually also stated in terms of the minimum spacing (in millimeters) between the two objects whereby the two objects are still distinguishable discretely. The method developed in this study is more accurate and also eliminates the discrepancies that might result using the conventional method of using target pair spacing in phantom. Measurements indicating the axial resolution should match to the baseline values within +/1 mm or +/1 %. If the variation is more than +/2mm or 2% for frequencies less than 4 MHz, service engineer must be contacted. Appropriate times for system resolution checks could be annual. Lateral Resolution The methodology proposes that the lateral resolution be recorded as the width of one of the targets in the axial resolution target group at depths of cm , cm and cm respectively . The suggested tolerance level is +/3mm and the service engineer must be contacted if it doesnÂ’t satisfy the criteria.

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85 Table 5-1. Suggested action and defect levels (A) Image quality Indicator Suggested defect levels Suggested action levels Display Monitor fidelity # gray bars displayed < control value 3 # gray bars displayed < control value –2, fuzzy or blooming annotation Image uniformity Change is > 20% from baseline Change is > 25% from baseline Depth of visualization Change is 1cm form baseline Change is 0.6 cm from baseline Vertical distance accuracy Shallow range Deep Range Error 2mm or 2% Error 1.5 mm or 1.5 % Horizontal distance accuracy Error 3mm or 3% Error 2 mm or 2 % (B) Phantom image quality indicator Suggested defect levels Suggested action levels Anechoic object observation/ Gray scale imaging Ratio is > 1.5 Ratio is > 2 Axial resolution In general greater than 1 mm, or any consistent measurable change from baseline 1mm, or 2mm if freq < 4 MHz, or any consistent measurable change from baseline Lateral resolution Change is 3cm form baseline Change is 4 cm from baseline Future Research More quantitative and definitive QC test results can be obtained with the aid of computerized analysis of the ultrasound images. The QC protocol developed in this study is implemented in software for analyzing stored images as shown in the Figure 5-1. To enable a fast interface Matlab was considered as the best choice for development environment. The software is in its initial stages of development and is a fixed sequence modular program. The software acquisition and interface package are yet to be developed and implemented. The module, which would generate reports generated directly using the software, after storing it as text files, is also incomplete. So the future resaerach would include completion of all these modules to make the QC program totally automated.

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86 Figure 5-1. Graphical User Interface (GUI) in Matlab for an automated US QC package The primary advantage of such a program is that the QC analysis would not only be objective but also automated. Identical analysis of images produced by different machines would be possible. A possible complication with a software system like this would be to ensure that there is no degradation of the images due to possible sampling errors associated with image-capture process.

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87 APPENDIX A QC PROTOCOL The ultrasound quality assurance program developed in this study is a routine evaluation of the ultrasound systems. It is divided in to three steps 1. Equipment evaluation 2. Phantom Measurements 3. Records and Scheduling Equipment Evaluation It includes inspections as well as tests to measure image quality and accuracy. Equipment inspections would include a review of each component in the system from the standpoint of safety and functionality. The SYSTEM EVALUATIONS include physical and mechanical inspection of the Main Unit, transducers, monitor, printer and accessories. The following general inspections are recommended in three areas: 1. Inventory: Check the ultrasound systems and accessories, include the manuals, repair records and QA records 2. Cleanliness: Check the scanner monitor, keyboard, and knobs for cleanliness, and then look over the transducers and holders. Inspect the machine housing, and then the air filters, clean the filters if necessary.

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88 3. Safety: Check the scanner, monitor and accessories should be properly scanned especially on portable units. Wheels should be fastened securely and the wheel locks should be working. Inspect all wires for cuts and fraying and ensure proper connection Phantom Measurements Image Analysis Protocol Operator selectable system controls To ensure repeatability of the quality control tests, it is necessary that certain of the operator selectable control values are consistent on every machine and are used identically for all subsequent testing periods. The controllable parameters for the tests are as follows: Time Gain Compensation TIME GAIN COMPENSATION (TGC) allows for enhancement of areas of interest by adjusting echo amplification at different depths. It compensates for losses in signal strength as the sound beam is attenuated with depth. Output Power OUTPUT POWER controls the amount of electrical energy delivered to the active transducer and, consequently, the amount of acoustic energy delivered to the tissue. Depth DEPTH magnifies image from one to five times normal size in the near field zone centered at the apex. As images are magnified, the displayed depth and viewing area are reduced.

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89 Gray Scale GRAY SCALE selects a post-processing curve that will determine the shades of gray assigned to specific signal amplitudes. The grayscale curve is a plot of signal amplitude versus brightness. Edge EDGE selects one of three edge enhancement filters. Dynamic Range DYNAMIC RANGE specifies the compressed range of returning signal amplitudes accepted for registration by the scanner circuitry. Reject REJECT selects different settings o flow grays and noise elimination. Scanning the Phantom All ultrasound images to be analyzed are obtained using RMI`s Precision Multipurpose Grey Scale Test Phantom (Model 403 GS). The phantom contains discrete pin targets and simulated cysts in tissue-mimicking material having a speed of sound, attenuation, and scattering properties similar to those of human liver tissue. The following considerations must be made when scanning the Model 403 GS phantom: Allow a 5-10 minute warm-up time for the scanner. The phantom should be placed on a flat and rigid surface to minimize movement.

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90 Either a generous amount of coupling gel or water poured directly into the water trough are necessary to provide proper sound transmission into the phantom. The scan plane of the transducer must be carefully aligned to the phantom to assure that the ultrasound beam strikes the line targets at the right angle. When using the Model 403 GS, the targets are bets imaged if the scanning plane of the transducer is properly oriented with respect to the scanning surface of the phantom. The main considerations concerning orientation are: a) being certain the image plane is parallel to the long sidewalls of the phantom. b) adjusting the scan plane tilt so the image plane is perpendicular to the reflectors in the phantom. Image collection A full field of view image of the Model 403 GS phantom is obtained for each transducer frequency and test. The images will then be sent to the archive and accessed later using Medisurf. Image analysis Uniformity Field uniformity is measured using the Model 403 GS phantom full field of view image. Place a region of interest (ROI) on the ultrasound image, near all four edges and the center, making sure that the region does not include any of the test pins. Right click on the ROI to generate a list of all the characteristics.

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91 Read and record the maximum and minimum pixel values, the mean value and standard deviation for the ROI. Enter the values in the QC sheet to see if the transducer passes the test. Distance accuracies Distance accuracy measurements for both horizontal and vertical directions are carried out similarly. Using the magnifying tool to magnify the targets whose separation us to be measured. Thresholding technique can be applied if absolutely necessary to improve the clarity of the image. Use the ruler tool to measure the distance between the targets of known spacing. Enter the values in the QC sheet to see if results are okayed. Spatial resolution To perform axial and lateral resolution measurements, the magnified images of each pin grouping are utilized. Thresholding can be activated if necessary. Magnify the first pin image of the second axial resolution target group such that individual pixels in the pins to be resolved are visible. Use the ruler tool and measure the length of the pin in the direction of the ultrasound beam and horizontally to measure the axial resolution and lateral resolution respectively. Repeat the measurements for various depths.

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92 Enter the values in the QC sheet to see if they compare well to the baseline values. It is not required that the test be repeated for various depths for the axial resolution test, since axial resolution only slightly changes with depth. Anechoic object perception and Gray scale evaluation For the anechoic object perception test the ROI is carefully placed and adjusted to overlap the anechoic gray scale target. The height and width of the anechoic object (0dB) was measured and entered into the QC sheets. The ratio will be automatically evaluated and the performance message would be generated automatically. For gray scale evaluation, similarly select ROIs to cover the other targets, measure the standard deviation, and mean value for each region. Feed the values into the data sheet to evaluate the gray scale range. Records and Scheduling Careful Planning and record keeping will help one get the most out this QA Program. Quality Assurance evaluations should be scheduled every 3 months for heavily used equipments Before being put into service, components such as new or repaired probes should be tested and established. The entire system can be tested at one time or the schedule can be staggered.

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93 APPENDIX B EXCEL PROGRAM WORKSHEET Medical Physics Survey: US Shands Hospital at UF Inventory A. Background information Calender Year(s) 2002 Room: Controlling Auth AIUM Unit: Equipment Manufacturer Date of Manu Model Serial Number Unit Transducers Test Precision Multi-purpose Grey-scale Jan, 2002 Equipment: Ultrasound Phantom RMI 403GS

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94 B.Visual Check List Pass/ Fail/ NA Action Cables Pass Housing Pass Transducers Connectors Pass Separations Pass Air Bubbles Pass Power Cord Pass Unit Controls Pass Wheels and wheel locks Pass Networking Pass Dust filters Pass CRT (C=50, B=65) Pass SMPTE Laser Camera Pass Gray Scale Contrast Objects visible on hardcopy cannot measure

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95 C.Test Summary Physical & Mechanical Inspection Pass Display Monitor Fidelity Hardcopy Monitor Fidelity Image Uniformity Depth of Visualization (Monitor) Depth of Visualization (Hard Copy) Vertical Accuracy Horizontal Accuracy Anechoic Object Distortion Anechoic Object Perception Axial Resolution Lateral Resolution Ring Down or Dead Zone Slice Thickness or Elevational Focus PACS Tests Linear Angle D.Comments Cannot measure slice thickness with RMI phantom. Prepared by: Date: Archana Mayani, BS Graduate Assistant Date: Manuel Arreola, Ph.D., DABR Diagnostic Physicist

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96 Section I Softcopy Fidelity (SMPTE)

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97 Section 1: Hardcopy vs Softcopy Fidelity (SMPTE) A. Contrast and Brightness Matching No settings for this test Baseline Settings: Power: Focal zone: Gain: System Default: TGC: Dynamic Range: FOV: Pre-processing: Reject: Post-processing: SMPTE Contrast:50 Brightness:65 Clinical Contrast:50 Brightness:50 Use bar pattern stored in Code K under video test patterns, Press ROI. Number of Gray Bars visible on display monitor: Date: Feb-01 Lowest Gray Bar 1 Highest Gray Bar 16 Tot. # of Bars 15 Monitor Focus Y Adequate (Y/N) Baseline Value for number of grayscale steps displayed on monitor: 16 (in two directions for a total of 32) Pass Monitor Fail if 5% and 95% patch not visible.

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98 Section 2 RMI Phantom

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99 A. Image Uniformity Use water instead of gel Baseline Settings: Anatomy: Abdomen1 Focal zone: all being used Gain: 30 System Default: E2, MD* A3 TGC: all centered Dynamic Range: 72 db Depth: 5 cm Edge Enhance: 2 TIS, MI, AO: <0.4, 1.1., 100% Transducer MHz: 8 Transducer: LA39 Contrast: 50 Brightness: 50 Baseline values: Axially: 15 Center: 15 Laterally: 15 Date: Vertical Banding none ok Axially noticeable serious Current value 15 Horizontal banding none ok Laterally noticeable serious Current value 15 Misc. Artifacts none ok Center noticeable serious Current value 15 Pass

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100 B. Depth of Visualization Baseline Value: 6 cm Date: On Display Display fail if Depth Vis change >.6 from base

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101 C. Vertical and Horizontal Accuracy Baseline Settings: Anatomy: Abdomen1 Focal zone: all being used Gain: 30 System Default: E2, MD* A3 TGC: all centered Dynamic Range: 72 db Depth: 5 cm Edge Enhance: 2 TIS, MI, AO: <0.4, 1.1., 100% Transducer MHz: 8 Transducer: LA39 Contrast: 50 Brightness: 50 Vertical Baseline Value: 1.01 cm (Measurement at filament: 1 & 2 cm Action Values Baseline ± 1.5 mm or 1.5%) = 1.16 cm & 0.86 cm Horizontal Baseline Value: 2.98 cm (Measurement at filament: 2 cm Action Values (Baseline ± 2.0 mm or 2%) = 3.18 cm & 2.78 Date: Vert Dist Monitor 1.01 Hor Dist Monitor 2.98 Fail Vert Dist Accu Fail if err > 1.5 mm Fail Hori Dist Accu Fail if err > 2mm

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102 D. Anechoic Object Perception Baseline Settings: Anatomy: Abdomen1 Focal zone: all being used Gain: 30 System Default: E2, MD* A3 TGC: all centered Dynamic Range: 72 db Depth: 5 cm Edge Enhance: 2 TIS, MI, AO: <0.4, 1.1., 100% Transducer MHz: 8 Transducer: LA39 Contrast: 50 Brightness: 50 Ratio of height (h) to width (w) Depth Object best seen 3 cm height (h) 0.14 width (w) 0.14 h/w 1.0 GRAY SCALE EVALUATION Baseline values:Object 1 15 Object 2 15 Object 3 15 Object 4 15 Date: clear ok Image Quality filled in jagged Object 1 Measurement Current Values std mean clear ok Image Quality filled in jagged Object 2 Measurement Current Values std mean

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103 clear ok Image Quality filled in jagged Object 3 Measurement Current Values std mean clear ok Image Quality filled in jagged Object 4 Measurement Current Values std mean

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104 E. Axial Resolution Baseline Settings: Anatomy: Abdomen1 Focal zone: all being used Gain: 30 System Default: E2, MD* A3 TGC: all centered Dynamic Range: 72 db Depth: 5 cm Edge Enhance: 2 TIS, MI, AO: <0.4, 1.1., 100% Transduce r MHz: 8 Transducer: LA39 Contrast: 50 Brightness: 50 Depth 4 Axial Resolution (check appropriate box) Baseline 0.25 2 mm Pass Axial Res Pass if >1mm for 4MHz or >transducers, >2mm for <4 MHz transducers

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105 F. Lateral Resolution Baseline Settings: Anatomy: Abdomen1 Focal zone: all being used Gain: 30 System Default: E2, MD* A3 TGC: all centered Dynamic Range: 72 db Depth: 5 cm Edge Enhance: 2 TIS, MI, AO: <0.4, 1.1., 100% Transducer MHz: 8 Transducer: LA39 Contrast: 50 Brightness: 50 Pin 2.3 Lateral Resolution (check appropriate box) Baseline 0.6 0.6 Pin 4.3 Lateral Resolution (check appropriate box) Baseline 0.8 0.8 Pin 11 Lateral Resolution (check appropriate box) Baseline 2 mm 1 mm 0.5 mm 0.25 mm

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106 Section 3 PACS Tests

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107 A. Linear Calipers Purpose: prove that the DICOM header info passed to PACS is true Test uneeded if 2C done on PACS rather than console Method: Scan object of known length into PACS, measure with PACS calipers Test object length: mm Caliper readout: mm error: Pass if error <1%

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108 B. Angle measurement Method: Scan object with known angle into PACS, measure with PACS calipers Test object angle: deg Caliper readout: deg error: Pass if error <1%

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111 APPENDIX C RESULTS Equipment ID: PAICAcI MR #: 00133333 Test 1: Caliper Accuracy Test Table C-1. Vertical caliper accuracy test measurement TRANSDUCER Phase I Phase II Phase III Phase IV s d s d s d s d PAICAc(C3*@2.5) 2.01 1.98 2.04 2.00 2.00 2.00 2.00 2.00 PAICAc(C3*@3.5) 2.01 2.01 2.01 2.00 2.01 2.00 2.00 2.00 PAICAc(C7*@5) 2.02 2.02 2.00 2.02 2.01 2.00 1.98 1.98 PAICAc(C7*@7) 2.02 2.01 2.00 2.02 2.02 2.00 1.98 2.01 PAICAc(EC7@3/5) 2.00 2.00 2.01 2.00 2.01 2.00 2.02 2.02 PAICAc(EC7@7 2.00 2.03 2.02 2.00 2.00 2.00 2.01 2.01 PAICAc(L7EF@7/3) 2.02 2.00 2.02 2.00 2.00 2.00 2.01 2.02 PAICAc(L7EF@10/5 ) 2.02 2.00 2.01 2.01 2.00 2.00 2.01 2.01 PAICAc(V4*@2.5) 2.02 1.99 2.01 2.01 2.00 1.99 2.01 1.99 PAICAc(V4*@3.5) 2.00 2.00 2.02 2.00 2.00 1.99 2.01 1.98 PAICAc(v4*@4) 2.01 1.98 2.06 2.00 1.99 2.00 2.02 2.02 Table C-2. Horizontal caliper accuracy measurement TRANSDUCER Phase I Phase II Phase III Phase IV s d s d s d s d PAICAc(C3*@2.5) 2.97 2.98 2.99 2.99 2.99 3.00 2.99 3.00 PAICAc(C3*@3.5) 2.97 2.98 2.99 2.99 2.99 3.00 3.01 3.02 PAICAc(C7*@5) 3.01 3.01 2.98 2.99 2.99 2.97 3.01 3.01 PAICAc(C7*@7) 3.03 3.01 2.98 2.97 3.03 3.02 2.98 2.98 PAICAc(EC7@3/5) 3.03 2.98 2.98 2.98 3.01 3.01 2.98 2.98 PAICAc(EC7@7 3.03 2.98 3.01 3.01 2.98 2.98 2.98 2.98 PAICAc(L7EF@7/3) 3.00 3.00 3.01 3.01 2.97 2.97 3.03 3.01 PAICAc(L7EF@10/5 ) 3.01 3.01 3.01 2.97 3.01 3.01 3.01 3.00 PAICAc(V4*@2.5) 3.01 2.98 3.01 3.03 3.00 3.01 3.00 3.00 PAICAc(V4*@3.5) 2.99 3.00 2.99 2.98 3.00 3.01 3.03 3.03 PAICAc(v4*@4) 2.99 2.98 2.98 2.98 3.00 2.99 3.03 2.98

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112 Test 2: Gray Scale Evaluation Table C-3. Brightness values for phantom objects TRANSDUCER Phase I Phase II Object 1 Object 2 Object 3 Object 4 Object 1 Object 2 Object 3 Object 4 PAICAc(C3*@2.5) 107.7 105.4 61.32 27.86 166.4 132.3 76.48 32.84 PAICAc(C3*@3.5) 119.8 116.6 72.83 25.84 192.6 161.8 105.2 24.08 PAICAc(C7*@5) 134.5 104.3 62.09 26.43 143.3 121.1 72.01 33.19 PAICAc(C7*@7) 95.47 117.3 72.81 30.63 151.4 130.7 82.82 31.65 PAICAc(EC7@3/5) 123.1 81.1 55.6 37.84 154.3 125 39.99 30.69 PAICAc(EC7@7 120.2 93.12 63.83 34.91 148.2 61.83 45.05 33.11 PAICAc(L7EF@7/3) 106.2 92.96 48.72 24.29 148 110.9 61.08 29.19 PAICAc(L7EF@10/5) 113.1 85.5 49.07 24.08 122.5 91.64 49.78 32.04 PAICAc(V4*@2.5) 107.6 71.89 37.09 24.64 119.4 78.16 41.16 23.91 PAICAc(V4*@3.5) 139.8 99.76 54.19 23.23 136.7 100.8 50.08 25.97 PAICAc(v4*@4) 121.8 98.44 45.84 25.22 154.7 112.6 64.05 32.02 TRANSDUCER Phase III Phase IV Object 1 Object 2 Object 3 Object 4 Object 1 Object 2 Object 3 Object 4 PAICAc(C3*@2.5) 159.6 112.4 62.28 25.47 166.4 132.3 76.48 32.84 PAICAc(C3*@3.5) 141.6 97.49 47.94 23.59 192.6 161.8 105.2 24.08 PAICAc(C7*@5) 143.3 121.1 72.01 33.19 135.1 111.1 80.56 22.03 PAICAc(C7*@7) 129.4 112.3 62.85 28.47 158.9 128 86.59 22.23 PAICAc(EC7@3/5) 142.1 120.5 49.9 24.77 110.5 103.7 46.47 21.07 PAICAc(EC7@7 117.6 120.8 55.12 23.24 102.3 96.78 65.48 29.5 PAICAc(L7EF@7/3) 136.5 103.5 61.03 26.3 191.2 158.5 91.97 36.02 PAICAc(L7EF@10/5) 116.4 76.27 50.63 20.95 153.6 123.1 71.08 23.81 PAICAc(V4*@2.5) 118.4 88.8 48.55 26.49 132.9 101.2 57.23 12.91 PAICAc(V4*@3.5) 148.9 112.5 65.43 30.61 144.3 109.5 67.87 12.91 PAICAc(v4*@4) 146 117 63.42 26.13 134.8 86.32 22.53 5.74

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113 Table C-4. Relative brightness values (to the background) for phantom objects TRANSDUCER Phase I Phase II Object 1 Object 2 Object 3 Object 4 Object 1 Object 2 Object 3 Object 4 PAICAc(C3*@2.5) 6.18 6.05 3.52 1.60 8.29 6.59 3.81 1.64 PAICAc(C3*@3.5) 9.21 8.96 5.60 1.99 13.65 11.47 7.45 1.71 PAICAc(C7*@5) 8.50 6.60 3.93 1.67 7.79 6.58 3.92 1.80 PAICAc(C7*@7) 6.10 7.50 4.66 1.96 8.35 7.21 4.57 1.75 PAICAc(EC7@3/5) 6.61 4.36 2.99 2.03 8.51 6.89 2.20 1.69 PAICAc(EC7@7 7.14 5.53 3.79 2.07 8.44 3.52 2.57 1.89 PAICAc(L7EF@7/3) 5.41 4.74 2.48 1.24 7.71 5.78 3.18 1.52 PAICAc(L7EF@10/5) 6.39 4.83 2.77 1.36 6.46 4.84 2.63 1.69 PAICAc(V4*@2.5) 6.41 4.28 2.21 1.47 6.12 4.01 2.11 1.23 PAICAc(V4*@3.5) 7.23 5.16 2.80 1.20 7.08 5.22 2.59 1.35 PAICAc(v4*@4) 6.81 5.50 2.56 1.41 7.82 5.69 3.24 1.62 TRANSDUCER Phase III Phase IV Object 1 Object 2 Object 3 Object 4 Object 1 Object 2Object 3Object 4 PAICAc(C3*@2.5) 8.73 6.15 3.41 1.39 7.93 6.30 3.64 1.56 PAICAc(C3*@3.5) 9.53 6.56 3.23 1.59 9.00 7.56 4.91 1.13 PAICAc(C7*@5) 8.00 6.76 4.02 1.85 6.62 5.44 3.95 1.08 PAICAc(C7*@7) 7.25 6.29 3.52 1.59 8.62 6.94 4.70 1.21 PAICAc(EC7@3/5) 7.78 6.59 2.73 1.36 5.42 5.09 2.28 1.03 PAICAc(EC7@7 6.08 6.25 2.85 1.20 5.42 4.61 3.12 1.40 PAICAc(L7EF@7/3) 6.95 5.27 3.11 1.34 7.21 5.98 3.47 1.36 PAICAc(L7EF@10/5) 5.19 3.40 2.26 0.93 8.41 6.74 3.89 1.30 PAICAc(V4*@2.5) 6.23 4.67 2.55 1.39 5.91 4.50 2.55 0.57 PAICAc(V4*@3.5) 7.98 6.03 3.51 1.64 7.13 5.41 3.35 0.58 PAICAc(v4*@4) 7.49 6.01 3.26 1.34 6.84 4.38 1.14 0.29

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114 Test 3: Uniformity Table C-5. Signal values in the selected ROIs TRANSDUCER Phase I Phase II Ax 1 Ax 2C Lat 1 Lat 2Ax 1 Ax 2C Lat 1 Lat 2 PAICAc(C3*@2.5) 14.4816.8617.4215.2617.8214.49 19.1620.08 20.6119.7 PAICAc(C3*@3.5) 12.445.23 13.0114.3613.3212.35 18.0514.11 17.6514.2 PAICAc(C7*@5) 13.6913.3315.8113.9 16.2215.12 17.0418.39 16.5517.89 PAICAc(C7*@7) 13.6612.8815.6416.0518.9 14.43 13.5118.13 18 18.34 PAICAc(EC7@3/5) 14.8912.8 18.6117.4615.0514.89 12.8 18.61 17.4615.05 PAICAc(EC7@7 13.8510.1216.8413.2411.3813.85 10.1216.84 13.2411.38 PAICAc(L7EF@7/3) 18.9915.9519.6121.3419.1518.99 15.9519.61 21.3419.15 PAICAc(L7EF@10/5) 18.8910.4 17.7119.1618.7118.89 10.4 17.71 19.1618.71 PAICAc(V4*@2.5) 17.9 17.6416.7918.4819.2917.9 17.6416.79 18.4819.29 PAICAc(V4*@3.5) 14.7 17.2219.3414.7818.0213.04 17.4119.3 17.3622.97 PAICAc(v4*@4) 15.4216.7517.8912.6313.8715.19 15.2519.78 17.8618 TRANSDUCER Phase III Phase IV Ax 1 Ax 2C Lat 1 Lat 2Ax 1 Ax 2C Lat 1 Lat 2 PAICAc(C3*@2.5) 13.0316.6718.2916.8616.2113.03 16.6715.65 16.8616.21 PAICAc(C3*@3.5) 13.2413.8414.8520.8815.3113.24 13.8414.85 20.8815.31 PAICAc(C7*@5) 16.0513.6517.9118.1 17.6214.86 16.8520.41 19.1520.07 PAICAc(C7*@7) 17.1814.9417.8517.0217.3716.12 15.4418.44 18.7416.82 PAICAc(EC7@3/5) 18.9416.5418.2720.5 21.7820.25 15.2 20.38 19.3115.38 PAICAc(EC7@7 18.2616.3519.3414.9614.0817.61 17.8221 18 18.11 PAICAc(L7EF@7/3) 18.5417.9919.6319.8620.1522.89 20.1426.51 23.5827.24 PAICAc(L7EF@10/5) 18.3511.8422.4319.3819.9421.51 16.6918.26 18.9820.92 PAICAc(V4*@2.5) 8.78 17.4119.0215.9619.6818.98 18 22.47 18.9517.73 PAICAc(V4*@3.5) 9.68 17.2118.6617.5114.8417.89 18.7120.24 17.2717.77 PAICAc(v4*@4) 10.6615.2919.4818.5316.4115.3 18.0519.71 15.8119.12

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115 Table C-6. Average signal values in the selected ROIs TRANSDUCER Phase I Phase II Phase III Phase IV A xia l Cente r Latera l A xia l Cente r Lateral A xia l Cente r Lateral A xia l Cente r Lateral PAICAc(C3*@2.5) 15.67 17.4216.5416.8320.08 20.1614.8518.2916.5414.85 15.6516.54 PAICAc(C3*@3.5) 8.835 13.0113.8415.214.11 15.9313.5414.8518.113.54 14.8518.1 PAICAc(C7*@5) 13.51 15.8115.0616.0818.39 17.2214.8517.9117.8615.86 20.4119.61 PAICAc(C7*@7) 13.27 15.6417.4813.9718.13 18.1716.0617.8517.215.78 18.4417.78 PAICAc(EC7@3/5) 13.85 18.6116.2613.8518.61 16.2617.7418.2721.1417.73 20.3817.35 PAICAc(EC7@7 11.99 16.8412.3111.9916.84 12.3117.3119.3414.5217.72 2118.06 PAICAc(L7EF@7/3) 17.47 19.6120.2517.4719.61 20.2518.2719.6320.0121.52 26.5125.41 PAICAc(L7EF@10/5 ) 14.65 17.7118.9414.6517.71 18.9415.122.4319.6619.1 18.2619.95 PAICAc(V4*@2.5) 17.77 16.7918.8917.7716.79 18.8913.119.0217.8218.49 22.4718.34 PAICAc(V4*@3.5) 15.96 19.3416.415.2319.3 20.1713.4518.6616.1818.3 20.2417.52 PAICAc(v4*@4) 16.09 17.8913.2515.2219.78 17.9312.9819.4817.4716.68 19.7117.47 Test 4: Depth of Penetration Table C-7. Maximum imaging depth TRANSDUCER Phase IPhase IIPhase II I Phase IV PAICAc(C3*@2.5) 16.03 15.98 15.93 15.56 PAICAc(C3*@3.5) 15.96 15.93 15.98 15.9 PAICAc(C7*@5) 9.16 9.12 9.17 10.09 PAICAc(C7*@7) 9.18 9.17 9.15 6.11 PAICAc(EC7@3/5) 7.71 9.15 7.72 7.25 PAICAc(EC7@7 9.2 6.71 7.21 4.76 PAICAc(L7EF@7/3) 7.83 7.3 7.33 7.81 PAICAc(L7EF@10/5) 7.81 7.3 7.4 5.33 PAICAc(V4*@2.5) 16.3 16.34 16.14 16.12 PAICAc(V4*@3.5) 16.19 16.16 16.16 14.09 PAICAc(V4*@4) 16.15 16.16 16.06 12.06

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116 Test 5: Spatial Resolution Table C-8. Axial resolution measurement TRANSDUCER Phase I Phase II Phase III Phase IV PAICAc(C3*@2.5) 1.5 1 1 1 PAICAc(C3*@3.5) 1.5 1.5 1 1 PAICAc(C7*@5) 1.5 1.5 2 2 PAICAc(C7*@7) 2 2 2 2 PAICAc(EC7@3/5) 1.5 1.5 1.5 1.5 PAICAc(EC7@7 1 1.5 1.5 2 PAICAc(L7EF@7/3) 2 1.5 2 2 PAICAc(L7EF@10/5) 2 2 1 2 PAICAc(V4*@2.5) 1.5 2 2 2 PAICAc(V4*@3.5) 1.5 2 1.5 2 PAICAc(v4*@4) 1 1.5 1 1 Table C-9. Lateral resolution measurement at various depths TRANSDUCER Phase I Phase II Phase III Phase IV s m d s m d s m d s m d PAICAc(C3*@2.5) 3.0 4.0 5.0 2.5 5.0 0.0 3.5 4.0 5.0 4.0 5.0 5.0 PAICAc(C3*@3.5) 1.5 3.0 3.0 2.0 3.0 4.0 1.0 2.0 3.0 2.0 5.0 7.0 PAICAc(C7*@5) 3.0 5.0 7.0 4.0 6.0 5.0 5.0 6.0 0.0 2.0 4.0 9.0 PAICAc(C7*@7) 4.0 6.0 4.0 3.0 5.0 4.0 4.0 7.0 5.0 4.0 5.0 0.0 PAICAc(EC7@3/5) 5.0 6.0 0.0 3.0 6.0 6.0 4.0 7.0 7.0 3.0 5.0 0.0 PAICAc(EC7@7 4.0 0.0 0.0 2.0 3.0 0.0 3.0 5.0 5.0 4.0 0.0 0.0 PAICAc(L7EF@7/3) 2.0 5.0 5.0 2.0 5.0 5.0 2.0 3.0 4.0 4.0 5.0 5.0 PAICAc(L7EF@10/5 ) 3.0 4.0 5.0 4.0 5.0 5.0 4.0 4.0 4.0 3.0 6.0 4.0 PAICAc(V4*@2.5) 1.5 4.0 5.0 2.0 5.0 4.0 3.0 4.0 0.0 3.0 4.0 4.0 PAICAc(V4*@3.5) 3.0 5.0 6.0 3.0 7.0 5.0 2.0 3.0 0.0 3.0 5.0 5.0 PAICAc(v4*@4) 2.5 4.0 5.0 1.5 3.0 5.0 1.5 3.0 4.0 0.0 4.0 3.0

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117 Equipment ID: SUFAcI MR #: 00144444 Test 1: Caliper Accuracy Test Table C-10. Vertical caliper measurement at various depths TRANSDUCER Phase I Phase II Phase III Phase IV s d s d s d s d SUFAcI(C7*@5) 2.01 1.99 2.00 1.99 1.98 1.99 1.99 2.01 SUFAcI(C7*@7) 2.01 2.01 1.98 1.98 1.98 1.98 2.00 2.01 SUFAcI(EC7@5) 2.02 2.02 2.01 2.02 2.00 2.02 2.00 2.01 SUFAcI(EC7@7) 2.02 2.02 2.01 2.02 2.00 2.02 2.00 2.01 SUFAcI(L7EF*@7/3) 2.02 2.02 2.01 2.02 2.02 2.02 2.02 2.01 SUFAcI(L7EF*@10/5 ) 2.01 2.02 2.01 2.02 2.00 2.01 2.00 2.02 SUFAcI(V4*@2.5) 2.01 1.99 1.98 1.99 1.99 1.98 1.97 2.02 SUFAcI(V4*@3.5) 2.01 1.99 2.00 1.99 1.98 2.00 2.02 2.02 SUFAcI(V4*@4) 1.99 1.98 2.00 1.99 1.99 1.99 2.00 2.00 SUFAcI(V7@5) 2.01 2.01 2.02 2.00 2.02 2.02 2.01 2.01 SUFAcI(V7@6) 2.01 2.02 2.00 2.00 2.02 2.02 2.01 2.01 SUFAcI(V7@7) 2.01 2.02 2.00 2.00 2.02 2.02 2.02 2.04 SUFAcI(V714s@5) 2.00 1.99 2.00 1.98 2.02 1.99 2.00 2.00 SUFAcI(V714s@7) 2.00 1.99 2.01 1.99 2.01 1.97 1.90 1.99 Table C-11. Horizontal caliper measurement at various depths TRANSDUCER Phase I Phase II Phase III Phase IV s d s d s d s d SUFAcI(C7*@5) 3.01 3.03 3.03 2.99 3.00 3.00 3.01 3.01 SUFAcI(C7*@7) 2.99 2.99 2.98 2.98 3.01 3.03 3.01 3.00 SUFAcI(EC7@5) 3.01 2.97 3.00 3.00 2.97 2.98 3.00 3.03 SUFAcI(EC7@7) 2.98 3.01 3.00 2.98 2.97 2.98 3.00 3.03 SUFAcI(L7EF*@7/3) 3.00 2.97 3.00 2.98 3.03 3.00 3.01 3.03 SUFAcI(L7EF*@10/5) 3.00 3.03 3.00 3.00 2.99 3.01 3.00 3.00 SUFAcI(V4*@2.5) 3.00 3.00 3.03 2.99 3.01 3.01 2.98 2.98 SUFAcI(V4*@3.5) 3.00 3.00 3.00 3.00 3.01 2.98 3.03 3.01 SUFAcI(V4*@4) 3.02 3.02 3.03 3.03 3.01 3.01 3.00 2.98 SUFAcI(V7@5) 2.98 2.98 2.98 2.98 3.00 3.00 3.03 3.00 SUFAcI(V7@6) 2.98 2.98 2.99 2.99 3.02 3.02 2.99 2.99 SUFAcI(V7@7) 2.98 2.98 2.99 3.00 2.99 2.98 2.99 3.00 SUFAcI(V714s@5) 3.03 2.98 3.00 3.00 2.99 2.98 3.00 3.00 SUFAcI(V714s@7) 3.02 2.98 3.00 3.00 2.99 2.98 3.00 3.00

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118 Test 2: Gray Scale Evaluation Table C-12. Brightness values for phantom objects TRANSDUCER Phase I Phase II Object 1 Object 2Object 3 Object 4Object 1 Object 2 Object 3 Object 4 SUFAcI(C7*@5) 150.7 126.4 83.69 36.16 146.5 127.5 93.43 49.36 SUFAcI(C7*@7) 133.9 133.1 93.97 38.78 133.2 125.6 91.03 40.38 SUFAcI(EC7@5) 117.7 101.1 60.12 37.87 117.7 101.1 60.12 37.87 SUFAcI(EC7@7) 118.7 98.75 55.74 33.69 118.7 98.75 55.74 33.69 SUFAcI(L7EF*@7/3) 122 103.1 60.59 34.06 122 140 91.44 35 SUFAcI(L7EF*@10/5) 111.6 84.83 59.07 36.17 111.6 123.9 82.49 35.89 SUFAcI(V4*@2.5) 137.1 107.1 69.7 34.79 145.6 116.5 77.83 40.91 SUFAcI(V4*@3.5) 134 104.2 63.21 34.33 134 104.2 63.21 34.33 SUFAcI(V4*@4) 180.6 146.2 96.78 39.02 149.3 123 81.63 37.13 SUFAcI(V7@5) 126.7 110.9 65.48 34.2 177.6 143.2 95.32 54.74 SUFAcI(V7@6) 121.5 106.9 71.35 37.43 159.8 136.4 102 64.88 SUFAcI(V7@7) 153.7 141.7 85.42 36.89 156.9 137.2 94.39 62.3 SUFAcI(V714s@5) 136.8 114 57.6 33.21 136.8 114 57.6 33.21 SUFAcI(V714s@7) 129.9 108.3 64.24 34.13 129.9 108.3 64.24 34.13 TRANSDUCER Phase III Phase IV Object 1 Object 2Object 3 Object 4Object 1 Object 2 Object 3 Object 4 SUFAcI(C7*@5) 151.2 130.1 91.26 39.54 173.8 137.2 97.57 38.55 SUFAcI(C7*@7) 131.6 128.4 92.4 42.73 166.5 141.3 96.52 40.85 SUFAcI(EC7@5) 117.7 101.1 60.12 37.87 167.3 148.1 90.67 49.55 SUFAcI(EC7@7) 189.4 162.9 108 54.86 157.7 144.7 108.5 55.97 SUFAcI(L7EF*@7/3) 156.3 138.1 93.8 45.73 156.3 127.7 94.62 45.73 SUFAcI(L7EF*@10/5) 133.5 126.3 81.24 40.78 133.5 107.6 72.79 40.78 SUFAcI(V4*@2.5) 144.4 121.1 76.6 40.54 138.6 113.9 64.42 36.15 SUFAcI(V4*@3.5) 134 104.2 63.21 34.33 159.3 124.2 84.15 38.68 SUFAcI(V4*@4) 147.9 121.4 83.92 44.09 147.9 124.6 77.5 32.74 SUFAcI(V7@5) 180 144.5 92.57 47.76 149.9 143 85.88 60.61 SUFAcI(V7@6) 162.3 140.5 101.8 60.7 155.7 139.8 94.14 43.36 SUFAcI(V7@7) 152 135.8 94.97 65.16 183.1 164.3 109.5 76.88 SUFAcI(V714s@5) 155.7 139.8 94.14 43.36 162.3 140.5 101.8 60.7 SUFAcI(V714s@7) 183.1 164.3 109.5 76.88 152 135.8 94.97 65.16

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119 Table C-13. Relative (to the background) brightness values for phantom objects TRANSDUCER Phase I Phase II Object 1 Object 2Object 3 Object 4Object 1 Object 2 Object 3 Object 4 SUFAcI(C7*@5) 10.20 8.55 5.66 2.45 8.96 7.79 5.71 3.02 SUFAcI(C7*@7) 8.81 8.76 6.19 2.55 8.75 8.25 5.98 2.65 SUFAcI(EC7@5) 8.03 6.90 4.10 2.58 7.57 6.50 3.86 2.43 SUFAcI(EC7@7) 8.19 6.82 3.85 2.33 6.63 5.52 3.12 1.88 SUFAcI(L7EF*@7/3) 7.41 6.26 3.68 2.07 5.97 6.85 4.47 1.71 SUFAcI(L7EF*@10/5) 6.70 5.09 3.55 2.17 6.92 7.69 5.12 2.23 SUFAcI(V4*@2.5) 9.19 7.18 4.67 2.33 8.46 6.77 4.53 2.38 SUFAcI(V4*@3.5) 6.40 4.98 3.02 1.64 9.01 7.01 4.25 2.31 SUFAcI(V4*@4) 8.34 6.75 4.47 1.80 8.89 7.33 4.86 2.21 SUFAcI(V7@5) 7.93 6.94 4.10 2.14 9.49 7.65 5.09 2.93 SUFAcI(V7@6) 6.53 5.74 3.83 2.01 8.50 7.26 5.43 3.45 SUFAcI(V7@7) 7.56 6.97 4.20 1.81 6.97 6.10 4.20 2.77 SUFAcI(V714s@5) 7.06 5.88 2.97 1.71 5.80 4.83 2.44 1.41 SUFAcI(V714s@7) 6.17 5.15 3.05 1.62 6.19 5.16 3.06 1.63 TRANSDUCER Phase III Phase IV Object 1 Object 2Object 3 Object 4Object 1 Object 2 Object 3 Object 4 SUFAcI(C7*@5) 10.00 8.61 6.04 2.62 10.31 8.14 5.79 2.29 SUFAcI(C7*@7) 8.62 8.40 6.05 2.80 8.71 7.39 5.05 2.14 SUFAcI(EC7@5) 7.16 6.15 3.65 2.30 8.74 7.74 4.74 2.59 SUFAcI(EC7@7) 9.92 8.54 5.66 2.87 9.37 8.60 6.45 3.33 SUFAcI(L7EF*@7/3) 7.83 6.92 4.70 2.29 6.46 5.27 3.91 1.89 SUFAcI(L7EF*@10/5) 8.53 8.08 5.19 2.61 7.46 6.02 4.07 2.28 SUFAcI(V4*@2.5) 7.84 6.57 4.16 2.20 9.09 7.47 4.22 2.37 SUFAcI(V4*@3.5) 7.89 6.14 3.72 2.02 9.87 7.70 5.22 2.40 SUFAcI(V4*@4) 8.51 6.98 4.83 2.54 8.42 7.10 4.41 1.86 SUFAcI(V7@5) 9.50 7.63 4.88 2.52 7.99 7.62 4.58 3.23 SUFAcI(V7@6) 7.53 6.52 4.72 2.82 5.63 5.05 3.40 1.57 SUFAcI(V7@7) 7.03 6.28 4.39 3.01 6.84 6.14 4.09 2.87 SUFAcI(V714s@5) 7.45 6.69 4.50 2.07 6.46 5.59 4.05 2.42 SUFAcI(V714s@7) 10.30 9.24 6.16 4.32 10.44 9.33 6.52 4.48

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120 Test 3: Uniformity Table C-14. Signal values for selected ROIs TRANSDUCER Phase I Phase II Ax1 Ax2 C Lat 1Lat 2Ax1 Ax2 C Lat 1 Lat 2 SUFAcI(C7*@5) 13.6 10.42 14.78 18.02 16.23 12.23 12.93 16.36 22.58 19.09 SUFAcI(C7*@7) 12.14 1.14 15.19 17.63 16.76 14.01 11.66 15.23 16.4 18.06 SUFAcI(EC7@5) 12.7 16.56 14.66 14.39 11.93 12.7 16.56 14.66 14.39 11.93 SUFAcI(EC7@7) 11.67 10.96 14.48 14.26 16.69 11.67 10.96 14.48 14.26 16.69 SUFAcI(L7EF*@7/3) 15.15 17.41 16.46 17.99 17.75 19.48 16.45 20.44 20.85 19.44 SUFAcI(L7EF*@10/5 ) 15.15 12.38 16.66 16.51 16.11 20.73 11.47 16.12 18.48 17.65 SUFAcI(V4*@2.5) 17.36 16.11 14.92 14.31 19.11 18.73 15.77 17.2 15.5 16.69 SUFAcI(V4*@3.5) 14.07 15.83 20.92 12.98 11.93 14.07 15.83 20.92 12.98 11.93 SUFAcI(V4*@4) 13.4 14.28 21.65 13 16.69 12.17 15.88 16.79 14.5 14.45 SUFAcI(V7@5) 14.74 13.16 15.97 16.52 12.91 15.46 14.13 18.71 13.82 14.94 SUFAcI(V7@6) 14.88 14.79 18.61 14.1 13.94 17.59 7.32 18.8 14.16 12.42 SUFAcI(V7@7) 13.01 9.3 20.34 18.15 17.92 13.01 9.3 20.34 18.15 17.92 SUFAcI(V714s@5) 16.58 12.56 19.39 18.22 18.55 16.58 12.56 19.39 18.22 18.55 SUFAcI(V714s@7) 18.43 12.98 21.05 17.78 15.04 18.43 12.98 21.05 17.78 15.04 TRANSDUCER Phase III Phase IV Ax1 Ax2 C Lat 1Lat 2Ax1 Ax2 C Lat 1Lat 2 SUFAcI(C7*@5) 13.68 13.65 15.12 17.19 19.01 14.18 6.89 16.85 16.75 16.93 SUFAcI(C7*@7) 13.9 11.36 15.28 16.67 17.23 15.15 9.73 19.12 19.09 19.23 SUFAcI(EC7@5) 16.2 16.96 19.13 19.64 11.59 16.2 16.96 19.13 19.64 11.59 SUFAcI(EC7@7) 14.48 10.28 19.09 14.25 12.34 13.8 12.14 16.82 16.51 14.83 SUFAcI(L7EF*@7/3) 18.98 15.88 19.95 21.07 19.72 17.67 12.51 24.21 20.99 20.22 SUFAcI(L7EF*@10/5) 20.45 11.44 15.64 19.19 16.26 16.99 12.55 17.88 17.19 16.64 SUFAcI(V4*@2.5) 14.42 15.47 18.43 17.31 16.5 14.81 16.96 15.25 15.19 16.83 SUFAcI(V4*@3.5) 12.54 14.36 16.13 12.13 14.17 12.54 14.36 16.13 12.13 14.17 SUFAcI(V4*@4) 12.08 13.4 17.39 18.24 11.9 12.22 12.83 17.56 11.79 13.89 SUFAcI(V7@5) 15.97 13.79 18.95 14.25 14.32 12.8 14.27 18.77 16.04 16.63 SUFAcI(V7@6) 17.8 11.86 21.54 14.33 13.97 15.63 14.78 27.66 21.91 17.62 SUFAcI(V7@7) 15.07 12.88 21.63 15.19 17.53 18.87 6.63 26.77 19.42 15.53 SUFAcI(V714s@5) 12.54 14.36 16.13 12.13 14.17 15.63 14.78 27.66 21.91 17.62 SUFAcI(V714s@7) 12.08 13.4 17.39 18.24 11.9 18.87 6.63 26.77 19.42 15.53

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121 Table C-15. Average signal values for selected ROIs TRANSDUCER Phase I Phase II Phase III Phase IV A xia l Cente r Latera l A xia l Cente r Latera l A xia l Cente r Latera l A xia l Cente r Latera l SUFAcI(C7*@5) 12.0114.78 17.13 12.58 16.36 20.84 13.6715.12 18.1 10.54 16.85 16.84 SUFAcI(C7*@7) 6.6415.19 17.2 12.84 15.23 17.23 12.6315.28 16.95 12.44 19.12 19.16 SUFAcI(EC7@5) 14.6314.66 13.16 14.63 14.66 13.16 16.5819.13 15.62 16.58 19.13 15.62 SUFAcI(EC7@7) 11.3214.48 15.48 11.32 14.48 15.48 12.3819.09 13.3 12.97 16.82 15.67 SUFAcI(L7EF*@7/3) 16.2816.46 17.87 17.97 20.44 20.15 17.4319.95 20.4 15.09 24.21 20.61 SUFAcI(L7EF*@10/5 ) 13.7716.66 16.31 16.116.12 18.07 15.9515.64 17.73 14.77 17.88 16.92 SUFAcI(V4*@2.5) 16.7414.92 16.71 17.25 17.2 16.1 14.9518.43 16.91 15.89 15.25 16.01 SUFAcI(V4*@3.5) 14.9520.92 12.46 14.95 20.92 12.46 13.4516.13 13.15 13.45 16.13 13.15 SUFAcI(V4*@4) 13.8421.65 14.85 14.03 16.79 14.48 12.7417.39 15.07 12.53 17.56 12.84 SUFAcI(V7@5) 13.9515.97 14.72 14.818.71 14.38 14.8818.95 14.29 13.54 18.77 16.34 SUFAcI(V7@6) 14.8418.61 14.02 12.46 18.8 13.29 14.8321.54 14.15 15.21 27.66 19.77 SUFAcI(V7@7) 11.1620.34 18.04 11.16 20.34 18.04 13.9821.63 16.36 12.75 26.77 17.48 SUFAcI(V714s@5) 14.5719.39 18.39 14.57 19.39 18.39 13.4516.13 13.15 15.21 27.66 19.77 Test 4: Depth of Penetration Table C-16.. Maximum imaging depth measurement TRANSDUCER Phase I Phase II Phase III Phase IV SUFAcI(C7*@5) 15.95 15.86 11.89 15.9 SUFAcI(C7*@7) 14.06 13.98 10.04 15.85 SUFAcI(EC7@5) 9.2 8.3 7.29 8.2 SUFAcI(EC7@7) 9.2 9.09 9.1 9.24 SUFAcI (L7EF*@7/3) 7.8 7.73 7.7 7.7 SUFAcI(L7EF*@10/5) 7.8 7.7 7.23 7.65 SUFAcI(V4*@2.5) 16.14 15.97 16.3 15.97 SUFAcI(V4*@3.5) 16.14 15.965 15.6 15.97 SUFAcI(V4*@4) 16.12 15.97 15.6 15.97 SUFAcI(V7@5) 9.25 9.26 7.23 9.06 SUFAcI(V7@6) 9.19 9.17 7.21 9.06 SUFAcI(V7@7) 9.25 9.11 6.18 9.03 SUFAcI(V714s@5) 9.3 9.01 9.1 8.98 SUFAcI(V714s@7) 8.25 9.07 8.7 7.98

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122 Test 5: Spatial Resolution Table C-17. Axial resolution measurement TRANSDUCER Phase I Phase II Phase IIIPhase IV SUFAcI(C7*@5) 1.5 1 1 1 SUFAcI(C7*@7) 1 2 1 1 SUFAcI(EC7@5) 1 1.5 1 1 SUFAcI(EC7@7) 1 1.5 1 1 SUFAcI(L7EF*@7/3) 2 2 1.5 1 SUFAcI(L7EF*@10/5) 1.5 1 0.5 1 SUFAcI(V4*@2.5) 2 1.5 1 1 SUFAcI(V4*@3.5) 1 1 1 1 SUFAcI(V4*@4) 1 1 1 1 SUFAcI(V7@5) 1 2 1.5 1 SUFAcI(V7@6) 1 1.5 1 2 SUFAcI(V7@7) 1 1.5 1 1.5 SUFAcI(V714s@5) 2 2 2 2 SUFAcI(V714s@7) 1.5 2 2 2 Table C-18. Lateral resolution measurement at various depths TRANSDUCER Phase I Phase II Phase III Phase IV s m d s m d s m d s m d SUFAcI(C7*@5) 1.5 3 4 2 2 4 2 3 4 3 3 5 SUFAcI(C7*@7) 1.5 2 0 4 4 0 3 2 0 2 2 0 SUFAcI(EC7@5) 2 2 4 3 5 6 2 2 4 2 2 4 SUFAcI(EC7@7) 1 3 5 2 5 6 2 2 4 2 2 4 SUFAcI(L7EF*@7/3) 2 3 4 2 3 3.5 2 3 3 4 4 5 SUFAcI(L7EF*@10/5) 2 3.5 4 2 2 2 2 3 3 4 4 4 SUFAcI(V4*@2.5) 2 5 5 2 4 4 2 2 5 2 2 3 SUFAcI(V4*@3.5) 2 4 5 1 2 4 2 3 3.52 2 2 SUFAcI(V4*@4) 2 4 4 1 3 3 2 2.5 3 2 2 2.5 SUFAcI(V7@5) 3 4 5 3 5 7 2 4 4 2 2 5 SUFAcI(V7@6) 2 3.5 4.5 2.5 4 5 2 2 5 3 3 4 SUFAcI(V7@7) 2 3.5 4 2 5 5 1 2 3 2.5 2.5 3 SUFAcI(V714s@5) 2 2 5 2 2 4 2 2 4 2 2 4 SUFAcI(V714s@7) 2 2 4 2 2 4 2 2 4 2 2 4

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123 Equipment ID: SUFGE700I MR #: 00166666 Test 1: Caliper Accuracy Test Table C-19. Vertical caliper measurement at various depths TRANSDUCER Phase I Phase II Phase III Phase IV s d s d s d s d SUFGE700I(348C@2) 2.01 1.98 1.98 2.03 1.98 1.98 1.99 1.98 SUFGE700I(348C@3) 2.01 1.98 1.98 1.98 1.98 1.98 1.99 1.98 SUFGE700I(348C@4) 2.01 2.01 2.01 1.99 1.98 1.98 1.99 1.98 SUFGE700I(546LC@4) 2.01 2.01 2.01 1.99 1.99 1.99 1.99 1.99 SUFGE700I(546LC@6) 2.01 2.01 2.01 1.99 2.00 2.02 1.99 1.99 SUFGE700I(548C@4) 2.01 1.98 2.02 1.98 2.03 1.98 1.98 1.98 SUFGE700I(548C@5) 2.01 1.98 2.03 1.98 2.03 1.98 1.98 1.99 SUFGE700I(548C@7) 2.02 1.98 2.02 1.98 2.02 1.99 1.98 1.99 SUFGE700I(618E@5) 2.02 1.99 2.02 1.98 2.02 1.98 2.00 1.99 SUFGE700I(618E@7) 2.02 1.99 2.02 1.98 1.99 2.01 2.00. 1.99 SUFGE700I(LA39C@8) 2.02 1.99 2.02 1.98 1.99 1.99 2.00 1.98 SUFGE700I(LA39C@9) 2.02 1.99 2.02 2.01 1.99 2.00 2.00 1.98 SUFGE700I(LA39C@11 ) 2.02 1.99 2.02 2.01 1.99 2.00 2.00 1.98 SUFGE700I(LA39C@12 ) 2.02 2.98 2.02 2.01 1.99 2.00 2.00 1.98 Table C-20. Horizontal caliper measurement at various depths TRANSDUCER Phase I Phase II Phase III Phase IV s d s d s d s d SUFGE700I(348C@2) 3.01 3.02 3.02 3.02 2.99 3.01 2.99 2.99 SUFGE700I(348C@3) 2.99 3.01 3.01 3.02 3.01 3.02 2.99 3.00 SUFGE700I(348C@4) 3.02 3.02 3.01 3.01 2.99 3.01 2.98 3.02 SUFGE700I(546LC@4) 3.00 3.00 3.00 3.02 3.03 3.03 2.98 3.02 SUFGE700I(546LC@6) 3.03 3.03 3.00 3.00 3.03 3.03 2.98 2.98 SUFGE700I(548C@4) 3.02 3.02 3.01 2.99 3.01 2.99 3.02 2.98 SUFGE700I(548C@5) 2.98 3.02 2.99 2.99 3.01 3.01 3.02 3.00 SUFGE700I(548C@7) 3.01 3.01 2.99 2.99 2.99 3.02 2.98 2.99 SUFGE700I(618E@5) 3.02 3.02 3.02 3.02 2.99 3.02 3.00 3.00 SUFGE700I(618E@7) 3.02 3.01 2.99 3.00 2.99 3.02 3.00 3.00 SUFGE700I(LA39C@8) 3.00 3.00 2.99 2.99 3.01 3.02 2.99 2.99 SUFGE700I(LA39C@9) 3.01 3.01 2.99 2.99 2.99 3.01 2.99 3.02 SUFGE700I(LA39C@11 ) 3.01 3.01 2.99 3.01 2.99 3.02 2.99 2.99 SUFGE700I(LA39C@12 ) 3.01 3.01 2.99 3.00 2.99 3.00 2.99 2.99

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124 TEST 2: GRAY SCALE EVALUATION Table C-21. Brightness values for phantom objects TRANSDUCER Phase I Phase II Object 1 Object 2 Object 3 Object 4Object 1 Object 2 Object 3 Object 4 SUFGE700I(348C@2) 133 109.4 72.55 21.88 118.3 81.48 46.7 4.36 SUFGE700I(348C@3) 130.6 103.3 68.17 19.16 117.5 85.99 42.98 6.84 SUFGE700I(348C@4) 136.1 104.2 71.5 25.03 131.2 93.41 60.58 14.58 SUFGE700I(546LC@4) 147.2 116.7 65.37 6.71 131.5 107.3 53.63 2.73 SUFGE700I(546LC@6) 153.9 119.4 56.23 2.13 159.9 132.6 63.65 8.8 SUFGE700I(548C@4) 136.2 114.2 76.14 19.29 129.5 108.3 63.45 7.51 SUFGE700I(548C@5) 133.6 105.6 72.07 8.89 136.1 122.2 74.04 14.01 SUFGE700I(548C@7) 130.2 106.3 69.2 15.95 177.2 132.1 79.88 14.53 SUFGE700I(618E@5) 12.8.88 130 79.32 33.75 149.1 122.1 72.14 35.43 SUFGE700I(618E@7) 134.4 125.1 83.31 40.66 115.9 98.86 58.41 29.24 SUFGE700I(LA39C@8) 118.9 98.89 59.83 9.36 127.3 101.9 54.54 9.46 SUFGE700I(LA39C@9) 120.6 96.49 66.97 9.66 103.6 83.25 40.37 0.67 SUFGE700I(LA39C@11) 136.6 123.3 89 27.94 119.1 96.54 54.5 4.74 SUFGE700I(LA39C@12) 117.9 104 65.34 20.87 114.4 98.66 65.92 24.38 TRANSDUCER Phase III Phase IV Object 1 Object 2 Object 3 Object 4Object 1 Object 2 Object 3 Object 4 SUFGE700I(348C@2) 127.2 95.84 64.47 12.16 104.9 80.37 45.05 12.07 SUFGE700I(348C@3) 141.7 108 70.04 22.83 112.5 84.37 52.05 13.31 SUFGE700I(348C@4) 129.4 101.5 72.81 24.81 110.3 84.49 55.43 12.88 SUFGE700I(546LC@4) 136.6 118.7 62.08 5.51 110.1 88 46.82 5.62 SUFGE700I(546LC@6) 159.4 130.4 71.17 7.68 116.6 91.59 41.6 3.19 SUFGE700I(548C@4) 111.5 89.92 58.52 9.07 117.3 92.6 62.97 12.85 SUFGE700I(548C@5) 116 100.2 62.04 9.96 105.6 83.75 53.53 12.49 SUFGE700I(548C@7) 114.6 95.21 57.88 5.27 96.31 76.9 47.61 8.87 SUFGE700I(618E@5) 139.5 128.2 87.43 34.87 115.9 98.86 58.41 29.24 SUFGE700I(618E@7) 108.1 100.4 53.25 8.55 127.3 101.9 54.54 9.46 SUFGE700I(LA39C@8) 118.9 98.89 59.83 9.36 127.3 101.9 54.54 9.46 SUFGE700I(LA39C@9) 100.4 82.91 49.75 4.68 122.5 96.22 57.25 9.05 SUFGE700I(LA39C@11) 136 119.2 79.36 22.15 124.8 104 61.55 9.61 SUFGE700I(LA39C@12) 115.9 98.86 58.41 29.24 118.9 98.89 59.83 9.36

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125 Table C-22. Relative (to the background) brightness values for phantom objects TRANSDUCER Phase I Phase II Object 1 Object 2 Object 3 Object 4Object 1 Object 2 Object 3 Object 4 SUFGE700I(348C@2) 10.1 8.307 5.509 1.661 7.423 5.115 2.932 0.274 SUFGE700I(348C@3) 10.78 8.52 5.62 1.58 7.03 5.15 2.57 0.41 SUFGE700I(348C@4) 9.86 7.55 5.18 1.81 8.00 5.69 3.69 0.89 SUFGE700I(546LC@4) 7.66 6.07 3.40 0.35 7.52 6.14 3.07 0.16 SUFGE700I(546LC@6) 7.98 6.19 2.92 0.11 7.38 6.12 2.94 0.41 SUFGE700I(548C@4) 10.26 8.60 5.73 1.45 6.96 5.82 3.41 0.40 SUFGE700I(548C@5) 11.54 9.11 6.22 0.77 8.59 7.72 4.67 0.88 SUFGE700I(548C@7) 10.46 8.54 5.56 1.28 11.57 8.63 5.22 0.95 SUFGE700I(618E@5) 10.95 6.80 4.15 1.77 8.64 7.08 4.18 2.05 SUFGE700I(618E@7) 9.48 8.82 5.88 2.87 7.55 6.44 3.81 1.91 SUFGE700I(LA39C@8) 8.61 7.16 4.33 0.68 7.38 5.91 3.16 0.55 SUFGE700I(LA39C@9) 6.40 5.12 3.55 0.51 5.65 4.54 2.20 0.04 SUFGE700I(LA39C@11) 7.93 7.16 5.17 1.62 7.45 6.04 3.41 0.30 SUFGE700I(LA39C@12) 6.80 6.00 3.77 1.20 6.06 5.23 3.49 1.29 TRANSDUCER Phase III Phase IV Object 1 Object 2 Object 3 Object 4Object 1 Object 2 Object 3 Object 4 SUFGE700I(348C@2) 8.977 6.764 4.55 0.858 7.058 5.408 3.032 0.812 SUFGE700I(348C@3) 10.87 8.28 5.37 1.75 8.88 6.66 4.11 1.05 SUFGE700I(348C@4) 10.46 8.20 5.89 2.01 10.59 8.11 5.32 1.24 SUFGE700I(546LC@4) 6.53 5.68 2.97 0.26 5.50 4.39 2.34 0.28 SUFGE700I(546LC@6) 7.44 6.09 3.32 0.36 5.41 4.25 1.93 0.15 SUFGE700I(548C@4) 8.14 6.57 4.27 0.66 9.42 7.44 5.06 1.03 SUFGE700I(548C@5) 9.98 8.62 5.33 0.86 9.44 7.48 4.78 1.12 SUFGE700I(548C@7) 9.83 8.17 4.96 0.45 10.83 8.65 5.36 1.00 SUFGE700I(618E@5) 8.64 7.94 5.42 2.16 11.12 9.49 5.61 2.81 SUFGE700I(618E@7) 6.69 6.22 3.30 0.53 6.35 5.09 2.72 0.47 SUFGE700I(LA39C@8) 6.25 5.20 3.15 0.49 6.03 4.83 2.58 0.45 SUFGE700I(LA39C@9) 5.55 4.58 2.75 0.26 7.30 5.74 3.41 0.54 SUFGE700I(LA39C@11) 6.27 5.49 3.66 1.02 5.60 4.67 2.76 0.43 SUFGE700I(LA39C@12) 7.18 6.13 3.62 1.81 6.25 5.20 3.15 0.49

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126 Test 3: Uniformity Table C-23. Signal values for selected ROIs TRANSDUCER Phase I Phase II Ax 1 Ax 2 C Lat 1Lat 2 Ax 1 Ax 2 C Lat 1Lat 2 SUFGE700I(348C@2) 13.97 13.92 13.17 15.13 11.48 14.72 18.33 15.93 14.88 11.78 SUFGE700I(348C@3) 12.38 14.71 12.12 10.09 9.9 14.88 14.51 16.71 13.97 20.72 SUFGE700I(348C@4) 9.4 10.71 13.81 10.63 9.01 13.1 19.11 16.41 12.02 19.5 SUFGE700I(546LC@4) 13.59 20.38 19.23 19.09 18.3 13.04 17.35 17.48 17.95 17.94 SUFGE700I(546LC@6) 14.51 16.48 19.28 20.68 18.22 14.25 17.69 21.67 15.85 18.33 SUFGE700I(548C@4) 13.02 11.27 13.28 13.79 14.09 14.7 16.76 18.61 19.76 14.4 SUFGE700I(548C@5) 11.65 11.15 11.58 11.73 14.19 17.23 12.99 15.84 15.8 15.73 SUFGE700I(548C@7) 11.42 8.77 12.45 12.42 13.73 14.13 8.82 15.31 10.34 16.26 SUFGE700I(618E@5) 14.38 14.51 19.12 21.11 15.56 14.99 16.16 17.25 16.79 15.59 SUFGE700I(618E@7) 13.05 8.66 14.18 16.64 13.26 14.81 10.22 15.34 15.66 11.43 SUFGE700I(LA39C@8) 11.42 8.77 12.45 12.42 13.73 14.81 10.22 15.34 15.66 11.43 SUFGE700I(LA39C@9) 13.97 14.02 18.84 15.09 16.9 15.36 13.86 18.32 15.93 15.35 SUFGE700I(LA39C@11) 13.55 12.27 17.22 19.77 17.65 12.99 13.46 15.98 15.42 15.89 SUFGE700I(LA39C@12) 17.6 12.64 17.33 18.11 17.72 15.31 6.9 18.88 15.44 15.09 TRANSDUCER Phase III Phase IV Ax 1 Ax 2 C Lat 1Lat 2 Ax 1 Ax 2 C Lat 1Lat 2 SUFGE700I(348C@2) 14.57 13.55 14.17 17.24 13.97 12.31 14.38 14.86 12.16 20.93 SUFGE700I(348C@3) 10.9 12.56 13.04 16.54 12.95 10.93 11.3 12.66 11.58 18.9 SUFGE700I(348C@4) 10.58 13.06 12.37 15.72 13.12 9.78 10.88 10.42 8.31 9.84 SUFGE700I(546LC@4) 13.99 19.22 20.91 21.62 20.48 13.32 19.37 20.03 20.23 19.58 SUFGE700I(546LC@6) 13.46 18.05 21.43 20.8 20.37 12.79 17.22 21.54 17.17 17.73 SUFGE700I(548C@4) 10.52 12.54 13.69 11.93 15.27 11.05 11.88 12.45 10.96 11.33 SUFGE700I(548C@5) 11.08 10.87 11.63 10.69 11.86 11.69 10.68 11.19 10.71 12.36 SUFGE700I(548C@7) 10.75 5.6 11.66 8.35 7.8 10.66 4.27 8.89 8.07 8.06 SUFGE700I(618E@5) 13.74 12.32 16.14 13.54 16.04 9.78 10.88 10.42 8.31 9.84 SUFGE700I(618E@7) 12.75 11.6 16.15 11.24 10.37 13.32 19.37 20.03 20.23 19.58 SUFGE700I(LA39C@8) 17.68 14.4 19.01 16.42 18.03 16.26 16.03 21.11 16.08 17.27 SUFGE700I(LA39C@9) 16.22 14.83 18.09 18.86 15.76 16.34 13.65 16.77 16.32 14.44 SUFGE700I(LA39C@11) 18.12 12.58 21.71 20.54 20.88 13.24 12.86 22.28 17.12 19.89 SUFGE700I(LA39C@12) 17.68 14.4 19.01 16.42 18.03 12.99 13.46 15.98 15.42 15.89

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127 Test 4: Depth of Penetration Table C-24. Maximum imaging depth measurement TRANSDUCER Phase I Phase II Phase III Phase IV SUFGE700I(348C@2) 16 16 15.9 15.8 SUFGE700I(348C@3) 16 16.1 15.9 15.8 SUFGE700I(348C@4) 16 16 15.9 15.8 SUFGE700I(546LC@4) 9.24 9.27 9.19 9.135 SUFGE700I(546LC@6) 9.24 9.24 9.19 SUFGE700I(548C@4) 15.8 16 15.8 15.8 SUFGE700I(548C@5) 15.9 16 15.8 15.8 SUFGE700I(548C@7) 15.9 16 15.7 15.8 SUFGE700I(618E@5) 9.18 9.16 9.21 9.13 SUFGE700I(618E@7) 9.13 9.15 9.12 9.17 SUFGE700I(LA39C@8) 5.75 5.83 5.795 5.71 SUFGE700I(LA39C@9) 5.78 5.78 5.71 5.69 SUFGE700I(LA39C@11) 5.78 5 5.71 5.71 SUFGE700I(LA39C@12) 5.83 Test 5: Spatial Resolution Table C-25. Axial resolution measurement TRANSDUCER Phase I Phase II Phase IIIPhase IV SUFGE700I(348C@2) 1.5 1 0.5 2 SUFGE700I(348C@3) 1 1 0.5 2 SUFGE700I(348C@4) 1 1 1 1 SUFGE700I(546LC@4) 1.5 2 1.5 1.5 SUFGE700I(546LC@6) 1.5 1.5 1 1.5 SUFGE700I(548C@4) 2 1 2 1.5 SUFGE700I(548C@5) 1.5 1 1.5 1 SUFGE700I(548C@7) 1 1 1 1 SUFGE700I(618E@5) 1 1.5 1.5 1 SUFGE700I(618E@7) 1 1 1.5 1 SUFGE700I(LA39C@8) 1 1 1 1 SUFGE700I(LA39C@9) 1.5 1.5 1 1 SUFGE700I(LA39C@11) 1.5 1 1 1 SUFGE700I(LA39C@12) 1.5 1.5 1 1

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128 Table C-26. Lateral resolution measurement at various depths TRANSDUCER Phase I Phase II Phase III Phase IV s m d s m d s m d s m d SUFGE700I(348C@2) 1 2 5 4 4 5 2 3 4 2 3 5 SUFGE700I(348C@3) 1 1.5 4 3 3 4 2 3 5 2 3 4 SUFGE700I(348C@4) 1 1.5 3 2 2 4 2 2 5 1 2 3.5 SUFGE700I(546LC@4) 1 1.5 3 1.5 1.5 4 1.5 3 3 1.5 1 3 SUFGE700I(546LC@6) 1.5 1 3 1 2 4 1.5 2 3 1.5 2 3 SUFGE700I(548C@4) 2 3 5 1 2 3 2 3 5 1.5 2 4 SUFGE700I(548C@5) 2 3 5 1 1 4 1 2 3 1 2 3 SUFGE700I(548C@7) 2 3 4 1 3 4 1 2 3 1 1.5 2 SUFGE700I(618E@5) 2 3 5 3 5 5 2 3 5 2 3 4 SUFGE700I(618E@7) 3 3 4 2 3 5 3 5 5 2 3 4 SUFGE700I(LA39C@8) 2 3 3 2 2 4 2 2.5 3 2 2 6 SUFGE700I(LA39C@9) 2.5 2 3 2 2 4 2 2.5 3 2 3 5 SUFGE700I(LA39C@11) 1 1.5 3 2 2 4 1 2 3 1 1 4 SUFGE700I(LA39C@12) 1 2 4 1 3 3 2 3 4 2 3 4

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129 Equipment ID: SUFGE700II MR #: 00177777 Test 1: Caliper Accuracy Test Table C-27. Vertical caliper measurement at various depths TRANSDUCER Phase I Phase II Phase III Phase IV s d s d s d s d SUFGE700II(348C@2) 1.99 1.99 1.98 1.98 1.99 2 1.98 1.98 SUFGE700II(348C@3) 1.99 1.97 2 2.01 1.99 1.99 1.98 1.98 SUFGE700II(348C@4) 2.02 1.98 2 2.01 1.99 2.02 1.98 1.98 SUFGE700II(546LC@4) 2 2 2 2.01 2 2 2 1.98 SUFGE700II(546LC@6) 2 1.99 2 2 2 2 2 2 SUFGE700II(548C@4) 2 1.99 2.01 1.98 2 1.98 2 2 SUFGE700II(548C@5) 2.01 1.99 2 1.97 2.02 1.98 2.03 1.98 SUFGE700II(548C@7) 2.01 2.01 2.01 2.02 1.98 1.98 2.02 1.99 SUFGE700II(LA39C@8) 2.01 2 2 2 1.99 2 2 2 SUFGE700II(LA39C@9) 2 2 2 2 1.99 2 2 2 SUFGE700II(LA39C@11 ) 2 2 2 2 1.99 2 2 2 SUFGE700II(LA39C@12 ) 2 2 2 2 1.99 2 2 2 Table C-28. Horizontal caliper measurement at various depths TRANSDUCER Phase I Phase II Phase III Phase IV s d s d s d s d SUFGE700II(348C@2) 2.99 2.99 2.98 2.98 3.01 3.01 2.99 2.99 SUFGE700II(348C@3) 2.99 2.99 2.99 2.99 2.99 2.99 2.99 3.01 SUFGE700II(348C@4) 2.99 2.99 2.99 2.99 3.02 3.02 2.99 3.02 SUFGE700II(546LC@4) 3.01 3.01 3.01 3.01 3.01 2.99 3 3.01 SUFGE700II(546LC@6) 3.01 3.01 3 2.98 3.01 2.99 3.01 2.98 SUFGE700II(548C@4) 2.99 2.98 3 3 3.01 3.01 2.98 2.99 SUFGE700II(548C@5) 2.99 2.98 2.99 2.98 3.02 3.01 2.99 3 SUFGE700II(548C@7) 2.99 2.98 2.99 3 3 3.01 2.99 3 SUFGE700II(LA39C@8) 2.99 2.99 2.99 3.01 3.01 2.98 2.99 3 SUFGE700II(LA39C@9) 3.01 2.99 3 3 3.01 3.01 3.01 3.01 SUFGE700II(LA39C@11 ) 3.02 3.01 3.01 3.02 3.01 3.01 3 3 SUFGE700II(LA39C@12 ) 3.01 3.01 3 3 3.01 3 3 3

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130 Test 2: Gray Scale Evaluation Table C-29. Brightness values for phantom objects TRANSDUCER Phase I Phase II Object 1Object 2Object 3Object 4 Object 1 Object 2Object 3 Object 4 SUFGE700II(348C@2) 113.7 87.5 64.69 14.09 157.2 133.2 94.1 29.65 SUFGE700II(348C@3) 104.5 101.6 61.37 18.54 151.7 131.4 87.11 30.55 SUFGE700II(348C@4) 119.3 96.49 72.95 34.22 172.4 149.9 106 42.61 SUFGE700II(546LC@4) 121.9 94.36 46.23 0.82 163.2 136.6 106 46.26 SUFGE700II(546LC@6) 121.6 14.8 39.36 2.62 125 93.3 44.96 4.31 SUFGE700II(548C@4) 99.12 78.85 62.46 19.01 172.4 149.9 106 42.61 SUFGE700II(548C@5) 89.16 97.58 52.66 17.06 177.1 151.2 111 34.83 SUFGE700II(548C@7) 105.9 78.75 73.21 21.82 167.8 140.1 96.37 27.05 SUFGE700II(LA39C@8) 89.16 97.58 52.66 17.06 151.7 131.4 87.11 30.55 SUFGE700II(LA39C@9) 95.35 95.89 35.45 6.03 167.5 144.5 94.93 31.84 SUFGE700II(LA39C@11) 111.5 98.32 56.08 9.45 135.7 119.9 79.96 23.73 SUFGE700II(LA39C@12) 119.1 101.3 64.47 16.41 124 110.1 74.42 39.53 TRANSDUCER Phase III Phase IV Object 1 Object 2 Object 3Object 4 Object 1 Object 2 Object 3Object 4 SUFGE700II(348C@2) 163.31 129.7 90.14 37.18 147.9 124.4 82.67 27.48 SUFGE700II(348C@3) 168.1 142.7 100.3 34.56 126.6 107.6 73.39 24.48 SUFGE700II(348C@4) 140.9 116.5 83.13 26.95 132.6 109.3 76.82 33.07 SUFGE700II(546LC@4) 193.8 168.2 105.6 21.66 160.9 129.9 69.01 9.79 SUFGE700II(546LC@6) 178.2 163.2 99.58 28.64 141.4 112.5 15.94 6.51 SUFGE700II(548C@4) 178.8 154.9 110.4 42.86 150.2 123.3 82.38 23.23 SUFGE700II(548C@5) 157.7 136.4 94.88 25.29 141.5 117 78.07 21.23 SUFGE700II(548C@7) 169.2 142.8 103.3 31.39 133.1 112.9 79.62 35.99 SUFGE700II(LA39C@8) 157.7 136.4 94.88 25.29 141.5 117 78.07 21.23 SUFGE700II(LA39C@9) 141 129.2 84.71 23.36 113 97.41 59.93 12.08 SUFGE700II(LA39C@11) 157.2 141.9 98.73 40.83 127.3 110.6 77.7 22.81 SUFGE700II(LA39C@12) 126.1 109.9 65.42 31.67 91.4 76.84 40.18 16.17

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131 Table C-30. Relative (to the background) brightness values for phantom objects TRANSDUCER Phase I Phase II Object 1 Object 2Object 3Object 4Object 1 Object 2 Object 3 Object 4 SUFGE700II(348C@2) 8.23 6.33 4.68 1.02 11.22 9.51 6.72 2.12 SUFGE700II(348C@3) 8.81 8.56 5.17 1.56 11.78 10.20 6.76 2.37 SUFGE700II(348C@4) 10.52 8.51 6.43 3.02 13.08 11.37 8.04 3.23 SUFGE700II(546LC@4) 6.06 4.69 2.30 0.04 11.24 9.41 7.30 3.19 SUFGE700II(546LC@6) 6.47 0.79 2.09 0.14 5.68 4.24 2.04 0.20 SUFGE700II(548C@4) 6.96 5.54 4.39 1.33 11.01 9.57 6.77 2.72 SUFGE700II(548C@5) 8.64 9.46 5.10 1.65 13.56 11.58 8.50 2.67 SUFGE700II(548C@7) 11.57 8.61 8.00 2.38 14.76 12.32 8.48 2.38 SUFGE700II(LA39C@8) 7.04 7.70 4.16 1.35 10.13 8.77 5.82 2.04 SUFGE700II(LA39C@9) 6.55 6.59 2.43 0.41 8.31 7.17 4.71 1.58 SUFGE700II(LA39C@11) 6.28 5.54 3.16 0.53 7.33 6.47 4.32 1.28 SUFGE700II(LA39C@12) 7.77 6.61 4.21 1.07 9.44 8.39 5.67 3.01 TRANSDUCER Phase III Phase IV Object 1 Object 2 Object 3Object 4 Object 1 Object 2 Object 3Object 4 SUFGE700II(348C@2) 13.35 10.69 7.43 3.06 10.95 9.21 6.12 2.04 SUFGE700II(348C@3) 13.20 11.21 7.88 2.71 10.04 8.53 5.82 1.94 SUFGE700II(348C@4) 12.13 10.02 7.15 2.32 11.23 9.25 6.50 2.80 SUFGE700II(546LC@4) 6.73 5.84 3.67 0.75 6.09 4.92 2.61 0.37 SUFGE700II(546LC@6) 8.02 7.35 4.48 1.29 6.36 5.06 0.72 0.29 SUFGE700II(548C@4) 12.17 10.55 7.51 2.92 11.49 9.42 6.30 1.78 SUFGE700II(548C@5) 12.38 10.70 7.45 1.99 11.85 9.79 6.54 1.78 SUFGE700II(548C@7) 15.18 12.80 9.26 2.82 13.17 11.16 7.88 3.56 SUFGE700II(LA39C@8) 11.35 9.81 6.83 1.82 9.50 7.85 5.24 1.42 SUFGE700II(LA39C@9) 9.23 8.46 5.54 1.53 6.03 5.20 3.20 0.64 SUFGE700II(LA39C@11) 8.99 8.11 5.64 2.33 7.25 6.30 4.42 1.30 SUFGE700II(LA39C@12) 6.42 5.60 3.33 1.61 5.93 4.98 2.61 1.05

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132 Test 3: Uniformity Table C-31. Signal values for selected ROIs TRANSDUCER Phase I Phase II Ax1 Ax2 C Lat1Lat2Ax1 Ax2 C Lat1 Lat2 SUFGE700II(348C@2) 12.07 13 13.8213.67 12.84 11.94 12.75 14.01 11.24 17.64 SUFGE700II(348C@3) 10.65 13.21 11.8711.84 12.99 11.06 14.8 12.88 9.69 14.37 SUFGE700II(348C@4) 11.56 11.46 11.3410.66 10.72 11.39 11.48 13.18 8.63 10.3 SUFGE700II(546LC@4) 17.26 16.15 20.1 17.27 18.06 13.97 20.8 14.52 19.99 18.87 SUFGE700II(546LC@6) 11.93 15.53 18.8 17.84 17.71 13.89 24.39 21.99 18.33 22.94 SUFGE700II(548C@4) 11.98 12.57 14.2411.61 13.5 13.26 12.82 15.66 11.82 15.67 SUFGE700II(548C@5) 8.68 9.62 10.329.3 11.07 10.52 12.13 13.06 10.43 14.03 SUFGE700II(548C@7) 12.58 5.27 9.15 8.31 8.6 12.78 4.27 11.37 9.989 10.94 SUFGE700II(LA39C@8) 11.98 12.57 14.2411.61 13.5 13.26 12.82 15.66 11.82 15.67 SUFGE700II(LA39C@9) 15.42 14.9 14.5616.1 15.17 18.88 15.63 20.15 16.85 19.23 SUFGE700II(LA39C@11) 15.23 14.28 17.7617.17 20.13 12.69 18.01 18.52 15.14 19.49 SUFGE700II(LA39C@12) 13.58 12.36 15.3312.27 13.54 14.17 10.91 13.13 14.49 14.6 TRANSDUCER Phase III Phase IV Ax1 Ax2 C Lat1Lat2Ax1 Ax2 C Lat1 Lat2 SUFGE700II(348C@2) 13.85 13.78 12.1412.01 15.4 11.89 13.85 13.5 14.77 11.62 SUFGE700II(348C@3) 10.59 11.61 12.7312.32 12.22 12.42 12.9 12.61 12.21 11.3 SUFGE700II(348C@4) 13.56 10.18 11.6213.35 8.36 10.85 10.68 11.81 11.6 17.92 SUFGE700II(546LC@4) 18.7 28.64 28.8 23.2 25.8 14.46 18.62 26.42 19.37 21.31 SUFGE700II(546LC@6) 14.34 28.42 22.2123 18.87 13.18 23.49 22.24 29.17 21.67 SUFGE700II(548C@4) 12.47 15.55 14.6916.93 12.8 10.97 12.95 13.08 13.89 11.46 SUFGE700II(548C@5) 11.17 11.77 12.7411.59 12.93 11.75 10.96 11.94 11.12 9.67 SUFGE700II(548C@7) 16.47 15.56 11.1510.53 5.44 12.37 4.44 10.11 11.39 9.47 SUFGE700II(LA39C@8) 12.47 15.55 14.6916.93 12.8 10.97 12.95 13.08 13.89 11.46 SUFGE700II(LA39C@9) 15.45 15.12 15.2814.74 15.6 16.17 14.43 18.75 16.43 14.43 SUFGE700II(LA39C@11) 16.95 11.22 17.5 17.49 16.97 12.13 11.83 17.56 16.37 15.42 SUFGE700II(LA39C@12) 19.66 5.35 19.6214.88 15.51 11.89 8.36 15.42 14.65 13.11

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133 Table C-32. Average signal values for selected ROIs TRANSDUCER Phase I Phase II Axial CenterLateral Axial Center Lateral SUFGE700II(348C@2) 12.54 13.82 13.26 12.35 14.01 14.44 SUFGE700II(348C@3) 11.93 11.87 12.42 12.93 12.88 12.03 SUFGE700II(348C@4) 11.51 11.34 10.69 11.44 13.18 9.47 SUFGE700II(546LC@4) 16.71 20.10 17.67 17.39 14.52 19.43 SUFGE700II(546LC@6) 13.73 18.80 17.78 19.14 21.99 20.64 SUFGE700II(548C@4) 12.28 14.24 12.56 13.04 15.66 13.75 SUFGE700II(548C@5) 9.15 10.32 10.19 11.33 13.06 12.23 SUFGE700II(548C@7) 8.93 9.15 8.46 8.53 11.37 10.46 SUFGE700II(LA39C@8) 12.28 14.24 12.56 13.04 15.66 13.75 SUFGE700II(LA39C@9) 15.16 14.56 15.64 17.26 20.15 18.04 SUFGE700II(LA39C@11) 14.76 17.76 18.65 15.35 18.52 17.32 SUFGE700II(LA39C@12) 12.97 15.33 12.91 12.54 13.13 14.55 TRANSDUCER Phase III Phase IV Axial CenterLateral Axial Center Lateral SUFGE700II(348C@2) 13.82 12.14 13.71 12.87 13.50 13.20 SUFGE700II(348C@3) 11.10 12.73 12.27 12.66 12.61 11.76 SUFGE700II(348C@4) 11.87 11.62 10.86 10.77 11.81 14.76 SUFGE700II(546LC@4) 23.67 28.80 24.50 16.54 26.42 20.34 SUFGE700II(546LC@6) 21.38 22.21 20.94 18.34 22.24 25.42 SUFGE700II(548C@4) 14.01 14.69 14.87 11.96 13.08 12.68 SUFGE700II(548C@5) 11.47 12.74 12.26 11.36 11.94 10.40 SUFGE700II(548C@7) 16.02 11.15 7.99 8.41 10.11 10.43 SUFGE700II(LA39C@8) 14.01 14.69 14.87 11.96 13.08 12.68 SUFGE700II(LA39C@9) 15.29 15.28 15.17 15.30 18.75 15.43 SUFGE700II(LA39C@11) 14.09 17.50 17.23 11.98 17.56 15.90 SUFGE700II(LA39C@12) 12.51 19.62 15.20 10.13 15.42 13.88

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134 Test 4: Depth of Penetration Table C-33. Maximum imaging depth measurement TRANSDUCER Phase I Phase II Phase III Phase IV SUFGE700II(348C@2) 16.1 15.9 15.8 15.9 SUFGE700II(348C@3) 16.1 16 15.8 16 SUFGE700II(348C@4) 16 15.89 15.8 15.9 SUFGE700II(546LC@4) 9.3 9.1 9.24 9.3 SUFGE700II(546LC@6) 9.29 9.3 9.24 9.3 SUFGE700II(548C@4) 16 16 15.9 16 SUFGE700II(548C@5) 16 16 15.9 16 SUFGE700II(548C@7) 15.9 16 15.9 15.5 SUFGE700II(LA39C@8) 5.89 5.89 5.78 5.81 SUFGE700II(LA39C@9) 5.89 5.89 5.78 5.84 SUFGE700II(LA39C@11) 5.89 4.84 5.77 4.34 SUFGE700II(LA39C@12) 5.65 3.36 4.35 3.38 Test 5: Spatial Resolution Table C-34. Axial resolution measurement TRANSDUCER Phase I Phase II Phase IIIPhase IV SUFGE700II(348C@2) 1 2 1 1.5 SUFGE700II(348C@3) 1.5 1.5 1.5 2 SUFGE700II(348C@4) 2 1 1 1 SUFGE700II(546LC@4) 2 2 1 1.5 SUFGE700II(546LC@6) 2 2 1 1 SUFGE700II(548C@4) 2 2 2 1.5 SUFGE700II(548C@5) 2 1.5 2 1.5 SUFGE700II(548C@7) 1.5 1 1.5 2 SUFGE700II(LA39C@8) SUFGE700II(LA39C@9) 1.5 2 2 2 SUFGE700II(LA39C@11) 1 1.5 2 2 SUFGE700II(LA39C@12) 1 1 1 1.5

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135 Table C-35. Lateral resolution measurement at various depths TRANSDUCER Phase I Phase II Phase III Phase IV s m d s m d s m d s m d SUFGE700II(348C@2) 3 4 7 3 4 6 2 3 5 2 3 4 SUFGE700II(348C@3) 3 3 5 3 4 6 2 3 5 2 3 3 SUFGE700II(348C@4) 2 3 5 3 3 6 2 2.5 4 2 2 4 SUFGE700II(546LC@4) 4 3 3 3 3 5 3 4 5 2 2 3 SUFGE700II(546LC@6) 3 3 4 3 5 4 3 4 5 2 2 3 SUFGE700II(548C@4) 2 3 4 2 3 4 3 5 5 3 3 4 SUFGE700II(548C@5) 3 5 4 2 2 3 3 4 5 2 4 4 SUFGE700II(548C@7) 3 5 4 2 3 4 2 4 4 2 3 4 SUFGE700II(LA39C@8) 3 5 4 2 3 4 2 4 4 2 3 4 SUFGE700II(LA39C@9) 4 4 4 3 4 4 3 4 4 3 4 4 SUFGE700II(LA39C@11 ) 3 3.5 4 3 5 4 3 4 4 3 3 4 SUFGE700II(LA39C@12 ) 2 4 4 3 4 4 3 4 4 2 3 4

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136 Equipment ID: SUFAcII MR #: 00188888 Test 1: Caliper Accuracy Test Table C-36. Vertical caliper measurement at various depths TRANSDUCER Phase I Phase II Phase III Phase IV s d s d s d s d SUFAcII(C7*@5) 2.02 2.02 2 1.99 2.02 2.02 1.99 2.02 SUFAcII(C7*@7) 2.02 2.01 2 2 1.99 2.02 1.99 2 SUFAcII(L7EF@7/3) 2 2 2.01 2.01 1.98 2.02 1.99 2 SUFAcII(L7EF@10/5) 2 2 2.01 2.01 1.99 2.02 1.99 2 SUFAcII(V4*@2.5) 2 2 2.01 2.02 1.97 1.99 2 2 SUFAcII(V4*@3.5) 1.99 1.99 2.02 1.99 1.98 1.98 2.01 2.01 SUFAcII(v4*@4) 2.01 1.98 2.02 2.01 1.99 1.99 1.98 1.98 SUFAcII(V714S@5) 2 2 2 2 2 2 2 2 SUFAcII(V714S@7) 2 2 2 2 2 2 2 2 Table C-37. Horizontal caliper measurement at various depths TRANSDUCER Phase I Phase II Phase III Phase IV s d s d s d s d SUFAcII(C7*@5) 2.99 3.01 3 2.99 3 3 3 3 SUFAcII(C7*@7) 2.9 3.02 3 2.98 3.01 2.98 2.99 2.99 SUFAcII(L7EF@7/3) 2.9 3.01 2.97 3 2.99 3.01 3 3 SUFAcII(L7EF@10/5) 2.9 3 3 2.97 3 3.01 3 3.01 SUFAcII(V4*@2.5) 3 2.99 3.01 2.98 3.01 2.99 3 3 SUFAcII(V4*@3.5) 3.01 2.98 3.03 3.03 3.01 3 3.03 3.03 SUFAcII(v4*@4) 3.01 2.98 3 2.99 3.01 3.01 3.03 3.03 SUFAcII(V714S@5) 3 3.03 2.98 2.99 3.02 3.02 2.98 2.98 SUFAcII(V714S@7) 3 3.03 3 3 3.02 3.02 3.01 3

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137 Test 2: Gray Scale Evaluation Table C-38. Brightness value for phantom objects TRANSDUCER Phase I Phase II Object 1Object 2 Object 3Object 4Object 1Object 2 Object 3 Object 4 SUFAcII(C7*@5) 151.3 128.8 79.3 24.44 151 121 75.13 29.65 SUFAcII(C7*@7) 165.3 142.3 94.28 36.25 133.5 131.8 85.64 29.94 SUFAcII(L7EF@7/3) 111.4 83.73 55.22 20.14 141.2 113 62.14 26.74 SUFAcII(L7EF@10/5) 112 83.28 53.72 18.87 136.3 110 54.29 22.44 SUFAcII(V4*@2.5) 179.8 133 83.48 36.13 132.4 95.96 57.75 28.26 SUFAcII(V4*@3.5) 199.2 153.2 100.8 33.19 152.4 114.6 76.84 32.45 SUFAcII(v4*@4) 189.2 148.7 101.8 38.07 163.1 125.4 68.46 25.36 SUFAcII(V714S@5) 137.5 108.4 68.62 28.53 159.9 117.2 66.21 33.79 SUFAcII(V714S@7) 135.7 110.6 65.02 24.27 148.8 123.2 73.43 27.32 TRANSDUCER Phase III Phase IV Object 1Object 2 Object 3Object 4Object 1Object 2 Object 3 Object 4 SUFAcII(C7*@5) 130.2 111.2 32.82 21.81 133.9 122.7 74.35 26.24 SUFAcII(C7*@7) 130.3 118.3 68.88 23.03 129.7 132.6 83.89 22.96 SUFAcII(L7EF@7/3) 130.3 17.85 54.08 24.62 136.8 11.02 50.3 22.64 SUFAcII(L7EF@10/5) 146.6 101.1 60.79 32.28 130.2 100.4 47.9 21.63 SUFAcII(V4*@2.5) 105.3 80.5 45.01 30.58 126.7 98.57 57.49 25.82 SUFAcII(V4*@3.5) 123.5 88.69 49.21 25.9 140.5 103.6 62.61 25.51 SUFAcII(v4*@4) 120.3 90.41 48.57 23.16 136.4 105.6 57.9 24.19 SUFAcII(V714S@5) 131.3 111.3 61.74 21.26 146.7 113.2 63.65 31.57 SUFAcII(V714S@7) 128.6 115.8 70.22 21.5 155 139.6 73.2 33.68

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138 Table C-39. Relative (to the background) brightness value for phantom objects TRANSDUCER Phase I Phase II Object 1Object 2 Object 3Object 4Object 1Object 2 Object 3 Object 4 SUFAcII(C7*@5) 6.97 5.93 3.65 1.13 8.72 6.99 4.34 1.71 SUFAcII(C7*@7) 8.55 7.36 4.88 1.88 6.91 6.82 4.43 1.55 SUFAcII(L7EF@7/3) 5.99 4.50 2.97 1.08 6.77 5.42 2.98 1.28 SUFAcII(L7EF@10/5) 6.44 4.79 3.09 1.09 7.63 6.16 3.04 1.26 SUFAcII(V4*@2.5) 7.66 5.67 3.56 1.54 7.20 5.22 3.14 1.54 SUFAcII(V4*@3.5) 8.53 6.56 4.32 1.42 8.09 6.08 4.08 1.72 SUFAcII(v4*@4) 7.89 6.20 4.24 1.59 9.14 7.02 3.84 1.42 SUFAcII(V714S@5) 6.41 5.05 3.20 1.33 7.66 5.61 3.17 1.62 SUFAcII(V714S@7) 6.34 5.17 3.04 1.13 7.50 6.21 3.70 1.38 TRANSDUCER Phase III Phase IV Object 1Object 2 Object 3Object 4Object 1Object 2 Object 3 Object 4 SUFAcII(C7*@5) 7.95 6.79 2.00 1.33 7.15 6.55 3.97 1.40 SUFAcII(C7*@7) 8.15 7.40 4.31 1.44 8.25 8.44 5.34 1.46 SUFAcII(L7EF@7/3) 5.74 0.79 2.38 1.08 7.10 0.57 2.61 1.17 SUFAcII(L7EF@10/5) 7.69 5.31 3.19 1.69 7.22 5.57 2.66 1.20 SUFAcII(V4*@2.5) 5.97 4.57 2.55 1.73 9.31 7.24 4.22 1.90 SUFAcII(V4*@3.5) 7.30 5.24 2.91 1.53 7.23 5.33 3.22 1.31 SUFAcII(v4*@4) 6.64 4.99 2.68 1.28 7.12 5.52 3.02 1.26 SUFAcII(V714S@5) 5.60 4.75 2.63 0.91 6.18 4.77 2.68 1.33 SUFAcII(V714S@7) 5.61 5.05 3.07 0.94 6.90 6.22 3.26 1.50

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139 Test 3: Uniformity Table C-40. Signal value for phantom objects TRANSDUCER Phase I Phase II Ax1 Ax2 C Lat 1 Lat 2 Ax1 Ax2 C Lat 1 Lat 2 SUFAcII(C7*@5) 15.69 11.58 21.72 18.61 24.89 15.34 13.87 17.32 19.59 17.53 SUFAcII(C7*@7) 17.09 13.54 19.33 17.41 17.9 15.48 13.01 19.32 17.71 19.17 SUFAcII(L7EF@7/3)19.88 18.18 18.6 19.06 17.59 19.2 18.26 20.86 18.36 20.07 SUFAcII(L7EF@10/5 ) 19.19 15.5 17.39 19.01 19.74 20.59 15.74 17.87 19.18 18.41 SUFAcII(V4*@2.5) 18.42 22.4 23.46 18.85 21.26 18.41 15.52 18.38 13.18 20.13 SUFAcII(V4*@3.5) 16.22 18.56 23.35 16.21 24 14.99 19.08 18.84 20.29 15.29 SUFAcII(v4*@4) 16.8 16.79 23.98 16.23 18.1 14.68 14.43 17.85 12.94 18.02 SUFAcII(V714S@5) 19.91 20.62 21.45 19.99 21.41 19.51 20.38 20.88 22.05 18.51 SUFAcII(V714S@7) 20.14 14.38 21.4 20.14 19.71 20.22 18.37 19.85 20.88 20.89 Test 4: Depth of Penetration Table C-41. Maximum imaging depth measurement TRANSDUCER Phase I Phase II Phase IIIPhase IV SUFAcII(C7*@5) 14.03 10 10.5 12.14 SUFAcII(C7*@7) 8.15 8.22 8.6 8.11 SUFAcII(L7EF@7/3) 7.83 7.83 7.77 7.81 SUFAcII(L7EF@10/5) 7.8 6.85 7.77 5.83 SUFAcII(V4*@2.5) 16.08 16.2 16 16.19 SUFAcII(V4*@3.5) 16.08 15.26 16.1 14.19 SUFAcII(v4*@4) 16.02 16.1 16.1 14.23 SUFAcII(V714S@5) 9.25 9.26 9.17 7.3 SUFAcII(V714S@7) 5.83 6.85 9.17 5.32 TRANSDUCER Phase III Phase IV Ax1 Ax2 C Lat 1 Lat 2 Ax1 Ax2 C Lat 1 Lat 2 SUFAcII(C7*@5) 15.31 10.81 16.37 16.42 19.43 14.5 13.96 18.73 17.74 19.47 SUFAcII(C7*@7) 13.11 10.76 15.99 18.63 20.15 16.06 13.52 15.72 16.28 20.72 SUFAcII(L7EF@7/3) 23.77 20.46 22.71 19.11 20.57 20.69 19.59 19.27 20.15 22.63 SUFAcII(L7EF@10/5) 23.73 15.57 19.06 20.91 20.07 19.4 14.41 18.04 20.63 20.2 SUFAcII(V4*@2.5) 18.18 19.57 17.63 13.5 17.23 10.98 11.7 13.61 12.68 11.38 SUFAcII(V4*@3.5) 14.69 21.03 16.92 13.18 12.62 15.25 15.43 19.43 16.87 12.76 SUFAcII(v4*@4) 13.89 18.14 18.12 11.58 14.2 13.84 14.05 19.15 17.01 14.28 SUFAcII(V714S@5) 19.09 13.05 23.45 20.54 23.2 20.82 17.24 23.73 20.87 20.99 SUFAcII(V714S@7) 17.53 12.38 22.91 21.53 20.85 22.8 21.15 22.46 20.6 20.93

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140 Test 5: Spatial Resolution Table C-42. Axial resolution measurement TRANSDUCER Phase I Phase II Phase IIIPhase IV SUFAcII(C7*@5) 3 2 1.5 SUFAcII(C7*@7) 2 1 1 1 SUFAcII(L7EF@7/3) 1.5 1.5 2 2 SUFAcII(L7EF@10/5) 1 1 1 1 SUFAcII(V4*@2.5) 2 1.5 0 0.5 SUFAcII(V4*@3.5) 1 1 0.5 0.5 SUFAcII(v4*@4) 0.5 0.5 0.5 SUFAcII(V714S@5) 1.5 1.5 1.5 3 SUFAcII(V714S@7) 0.5 1.5 2 2 Table C-43. Lateral resolution measurement at various depths TRANSDUCER Phase I Phase II Phase III Phase IV s m d s m d s m d s m d SUFAcII(C7*@5) 3 5 5 3 5 0 2 3 0 SUFAcII(C7*@7) 3 3 0 3 5 0 2 3 0 2 3 0 SUFAcII(L7EF@7/3) 3 4 5 2 3 5 2 4 5 2 3 4 SUFAcII(L7EF@10/5) 3 3.5 4 2 2 4 2 5 4 2 3 3 SUFAcII(V4*@2.5) 2 3 5 2 4 6 0 0 4 1 3 4 SUFAcII(V4*@3.5) 2 3 4 1 2 1 3 4 1 4 3 SUFAcII(v4*@4) 1 4 3 1 3 4 1 2 3 SUFAcII(V714S@5) 2 3 3 2 3 4 2 4 4 3 5 7 SUFAcII(V714S@7) 2 3 3 3 3 3 3 5 4 3 5 5

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141 LIST OF REFERENCES A User’s Guide. GAMMEX RMI 403GS Precison Multi-purpose Grey Scale Test Instrument. GAMMEX RMI, Middleton, WI, 1996. AIUM Task Group Report-Part II: Digital Methods (Stage 1) Methods for measuring performance of pulse-echo ultrasound equipment, American Institute of Ultrasound in Medicine, Laurel, MD; 1995. Barret J, Gareth C, Thorne A, Halliwell M. Quality assurance of ultrasound instruments by monitoring the monitor, Physics in Medicine and Biology 38: 1601-1609; 1993. Cameron JR. & Skofronick. JG. Medical Physics. 6th ed. John Wiley & Sons, New York; 1978. Currey TS, Dowdey JE, Murry RC. Christensen’s Physics of Diagnostic Radiology. 7th ed. Lea & Febiger, Philadelphia; 1990. Goldberg B & Wells P. Ultrasonics in Clinical Diagnosis, Churchill Livingston, London; 1983. Goldstein A. Slice Thickness measurements, Journal of Ultrasound in Medicine 7 (9): 487-98; 1988 Goldstein A. Comment on “Real-time B-mode ultrasound quality control test procedures,” Medical Physics 25 (8): 1547-54; 1998 Goldstein A. The use of urethane rubber phantoms in ultrasound quality assurance measurements, Journal of Ultrasound in Medicine, 2000, 19 (12): 882; 2000 Goldstein A. Errors in ultrasound digital image distance measurements, Ultrasound in Medicine and Biology 26(7): 1125-32; 2000 Goodsitt MM, Carson PL, Witt S, Hykes DL, Kofler JM Jr. Real-time B-mode ultrasound quality control test procedures. Report of AAPM Ultrasound Task Group No. 1. Medical Physics 25 (8): 1385-406; 1998 Goodsitt MM. Response to comment on “Real-time B-mode ultrasound quality control test procedures,” Medical Physics 27(11): 2636; 1998 Kollmann C. A protocol for routine quality control of function and image quality of medical ultrasound systems, Ultrasound in Medicine and Biology, (20) 1:S84; 1994, (a).

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142 Kollmann C. Results of a new routine quality control test system for medical ultrasound systems, Ultrasound in Medicine and Biology 1 20: S79; 1994, (b). Kollmann C, H. Bergmann. First experiences with a quality assurance concept for ultrasound B-mode imaging systems used in clinical routine, WFUMB abstract; 2000: A243. Metcalfe SC, Evans JA. A study of the relationship between routine ultrasound quality assurance parameters and subjective operator image assessment, The British Journal of Radiology 65: 570-575; 1992 NCRP Report No 99, “Quality assurance for diagnostic imaging. National Council on Radiation Protection and Measurements,” Bethesda, MD; 1988. Njeh CF, Chen MB, Fan B, Fuerst T, Wu C, Diessel E, Hans D. The impact of temperature on quantitative ultrasound: an in-vitro study using phantoms, Journal of Bone and Mineral Research 14:S500; 1999. Rownd JJ, Madsen EL, Zagzebski JA, Frank GR, Dong F. Phantoms and automated system for testing the resolution of ultrasound scanners, Ultrasound in Medicine and Biology 23(2): 245-60; 1997

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143 BIOGRAPHICAL SKETCH Archana Mayani was born in Bombay (now Mumbai), India, in 1978 to Dinesh and Devyani Mayani. She attended St AnneÂ’s Girls High School until matriculation in 1994. She entered Mahatma Gandhi Missions` College of Engineering and Technology in New Bombay, India, in December 1994 majoring in biomedical engineering. She was accepted at the University of Florida, Gainesville, Florida, in fall 2000 for the Master of Science program in biomedical engineering with a research assistantship provided by the Nuclear Science and Radiological Engineering Department under the guidance of Dr. David Hintenlang. She joined Shands Hospital at University of Florida in fall 2001, with a graduate research assistantship provided by the Department of Radiology, under the supervision of Dr. Manuel Arreola, to perform the research leading to a Master of Science degree.