<%BANNER%>

Complete Internal Photon Dosimetry Characterization of the University of Florida Newborn Hybrid Computational Phantoms

Permanent Link: http://ufdc.ufl.edu/UFE0041356/00001

Material Information

Title: Complete Internal Photon Dosimetry Characterization of the University of Florida Newborn Hybrid Computational Phantoms
Physical Description: 1 online resource (107 p.)
Language: english
Creator: Wayson, Michael
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: computational, dosimetry, hybrid, internal, phantom, photon, uf
Nuclear and Radiological Engineering -- Dissertations, Academic -- UF
Genre: Nuclear Engineering Sciences thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: A very important aspect of nuclear medicine imaging that is always in need of improvement is organ dosimetry. Since nuclear medicine imaging is based on the biodistribution of an administered radiopharmaceutical, radiation is emitted from the set of organs to which the radiopharmaceutical localizes. The determination of tissue absorbed dose from radiations emitted from inside the human body is known as internal dosimetry and is an integral part of performing risk assessment for nuclear medicine imaging. Computational radiation dosimetry is typically performed for such procedures owing to the difficulties of using physical phantoms and dose measuring devices for organ dose assessment. This study discusses the recent advancements in computational dosimetry methods, develops an improved method of determining dose to the human skeleton from incident photons, and calculates a new comprehensive set of photon specific absorbed fractions for the University of Florida newborn hybrid phantoms for use in internal dosimetry estimates. The set of specific absorbed fractions can be used to calculate the effective dose for any nuclear medicine imaging procedure, provided the radiopharmaceutical biokinetics and radionuclide decay information are known. Accurate dosimetry is needed in nuclear medicine imaging for the purpose of reducing patient risk and developing secondary cancer risk models. The results of this study provide the latest improvement in photon specific absorbed fractions and will be extended to the complete University of Florida hybrid computational phantom series in the future.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Michael Wayson.
Thesis: Thesis (M.S.)--University of Florida, 2009.
Local: Adviser: Bolch, Wesley E.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2011-12-31

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0041356:00001

Permanent Link: http://ufdc.ufl.edu/UFE0041356/00001

Material Information

Title: Complete Internal Photon Dosimetry Characterization of the University of Florida Newborn Hybrid Computational Phantoms
Physical Description: 1 online resource (107 p.)
Language: english
Creator: Wayson, Michael
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: computational, dosimetry, hybrid, internal, phantom, photon, uf
Nuclear and Radiological Engineering -- Dissertations, Academic -- UF
Genre: Nuclear Engineering Sciences thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: A very important aspect of nuclear medicine imaging that is always in need of improvement is organ dosimetry. Since nuclear medicine imaging is based on the biodistribution of an administered radiopharmaceutical, radiation is emitted from the set of organs to which the radiopharmaceutical localizes. The determination of tissue absorbed dose from radiations emitted from inside the human body is known as internal dosimetry and is an integral part of performing risk assessment for nuclear medicine imaging. Computational radiation dosimetry is typically performed for such procedures owing to the difficulties of using physical phantoms and dose measuring devices for organ dose assessment. This study discusses the recent advancements in computational dosimetry methods, develops an improved method of determining dose to the human skeleton from incident photons, and calculates a new comprehensive set of photon specific absorbed fractions for the University of Florida newborn hybrid phantoms for use in internal dosimetry estimates. The set of specific absorbed fractions can be used to calculate the effective dose for any nuclear medicine imaging procedure, provided the radiopharmaceutical biokinetics and radionuclide decay information are known. Accurate dosimetry is needed in nuclear medicine imaging for the purpose of reducing patient risk and developing secondary cancer risk models. The results of this study provide the latest improvement in photon specific absorbed fractions and will be extended to the complete University of Florida hybrid computational phantom series in the future.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Michael Wayson.
Thesis: Thesis (M.S.)--University of Florida, 2009.
Local: Adviser: Bolch, Wesley E.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2011-12-31

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0041356:00001


This item has the following downloads:


Full Text

PAGE 1

COMPLETE INTERNAL PHOTON DO SIMETRY CHARACTERIZATION OF THE UNIVERSITY OF FLORIDA NEWBORN HYBRID COMPUTATIONAL DOSIMETRY PHANTOMS By MICHAEL B. WAYSON A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2009 1

PAGE 2

2009 Michael B. Wayson 2

PAGE 3

To my family, who has always encouraged my de sire for higher education. To my beautiful fiance, for whom this work is but one more st ep towards our wonderful life together. To my Lord and Savior Jesus Christ, without whom I would not be in the position that I am. 3

PAGE 4

ACKNOWLEDGMENTS I thank Dr. Wesley Bolch for his guidance, di rection, and input, Dr. David Hintenlang for his critiques and input, Dr. Choonsik Lee for his immense technical s upport for MCNPX, and Arthur Adkins for troubleshooting my many issues with the Advanced Laboratory for Radiation Dosimetry Studies (ALRADS) comput er cluster. I thank my family and my fiance, Leslie, for their continual support and encouragement. Fi nally, I thank God for blessing me with the opportunity and ability to pur sue a rewarding career. 4

PAGE 5

TABLE OF CONTENTS Page ACKNOWLEDGMENTS ............................................................................................................... 4LIST OF TABLES ...........................................................................................................................7LIST OF FIGURES .........................................................................................................................8LIST OF ABBREVIATIONS ......................................................................................................... .9ABSTRACT ...................................................................................................................... .............11CHAPTER 1 INTRODUCTION ................................................................................................................ ..13Background .................................................................................................................... .........13History of Computational Dosimetry Phantoms .....................................................................15Purpose of Study .....................................................................................................................192 MATERIALS AND METHODS ...........................................................................................24UF Newborn Hybrid Dosimetry Phantom ..............................................................................24Subsegmented Skeleton Development ...................................................................................26Skeletal Photon Dose Response Functions .............................................................................28Computational Dosimetry Simulations ...................................................................................31Internal Dosimetry Formulation .............................................................................................36Renal Function Case Study .....................................................................................................39Clinical Aspects ...............................................................................................................39Dosimetry Assessment ....................................................................................................40Biokinetics ................................................................................................................40Whole-body effective dose .......................................................................................413 RESULTS ..................................................................................................................... ..........49Skeletal Dose Response Functions .........................................................................................49Specific Absorbed Fractions ...................................................................................................51Renal Function Case Study .....................................................................................................514 DISCUSSION .................................................................................................................. .......59ORNL Dose Response Functions ...........................................................................................59ORNL Newborn Specific Absorbed Fractions .......................................................................60Renal Function Case Study .....................................................................................................615 CONCLUSION .................................................................................................................. .....67 5

PAGE 6

APPENDIX A SAMPLE FILES ................................................................................................................ .....69B ORIGINAL CODES .............................................................................................................. .96LIST OF REFERENCES .............................................................................................................104BIOGRAPHICAL SKETCH .......................................................................................................107 6

PAGE 7

LIST OF TABLES Table Page 2-1 Active marrow distribution comparison ............................................................................43 2-2 Mineral bone distri bution in the UF newborn hybrid phantoms. .......................................44 2-3 Source organs for the male and female UF newborn hybrid phantoms. ............................45 2-4 Biokinetic parameters for 99mTc-DMSA for the newborn patient .....................................45 3-1 Specific absorbed fractions for the liver source in the female UF newborn hybrid phantom..............................................................................................................................53 3-2 Source organ residence times for 99mTc-DMSA in a newborn ..........................................55 3-3 Internal dosimetry result s and tissue weighting factors for the renal function case study. ........................................................................................................................ ..........55 4-1 Newborn skeletal dose re sponse function comparison. .....................................................63 4-2 Newborn specific absorbed fraction comparison ...............................................................64 4-3 Renal function dosimetry comparison ...............................................................................65 7

PAGE 8

LIST OF FIGURES Figure Page 1-1 The first stylized model of the trunk of an adult human ....................................................21 1-2 The MIRD Pamphlet No. 5 revised st ylized computational dosimetry phantom .............22 1-3 The complete current ORNL stylized computational dosimetry phantoms .......................22 1-4 The VIP-Man voxel phantom ............................................................................................23 1-5 A representative set of voxel phantoms for the GSF family of voxel phantoms. ..............23 2-1 Coronal and sagittal views of the UF newborn voxel computational dosimetry phantom..............................................................................................................................46 2-2 Steps in the process of converting the original new born voxel model into a NURBS model and voxelizing for input into MCNPX....................................................................47 2-3 The UF newborn hybrid female phantom in NURBS format ............................................47 2-4 Sample bone sites of the UF newborn hybrid phantom heterogeneous skeleton. .............48 2-5 Voxelized UF newborn hybrid female phantom. ...............................................................48 3-1 Dose and kerma response functions. ..................................................................................56 3-2 Skeletal dose response func tions for all bone sites. ...........................................................57 3-3 Specific absorbed fractions from the liv er source in the female UF newborn hybrid phantom..............................................................................................................................58 4-1 UF newborn hybrid phantom and ORNL adult male stylized phantom photon dose response functions ..............................................................................................................66 8

PAGE 9

LIST OF ABBREVIATIONS AF absorbed fraction ALRADS Advanced Laboratory fo r Radiation Dosimetry Studies AM active marrow CB cortical bone CPE charged particle equilibrium CT computed tomography DMSA dimercaptosuccinic acid DRF dose response function EGSnrc Electron-Gamma-Shower National Research Council ICRP International Commi ssion on Radiological Protection IDL Interactive Data Language KERMA kinetic energy released per unit mass MATLABTM matrix laboratory MCNP5 Monte Carlo n-particle version 5 MCNPX Monte Carlo n-particle extended MIRD Medical Intern al Radiation Dose NURBS non-uniform rational b-splines OLINDA organ level internal dose assessment ORNL Oak Ridge National Laboratory PET positron emission tomography PIRT paired-image radiation transport RST residual soft tissue SAF specific absorbed fraction SNM Society of Nuclear Medicine 9

PAGE 10

SPECT single photon emission tomography TB trabecular bone TLD thermoluminescent dosimeter TM50 bone endosteum UF University of Florida 10

PAGE 11

Abstract of Thesis Presen ted to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science COMPLETE INTERNAL PHOTON DO SIMETRY CHARACTERIZATION OF THE UNIVERSITY OF FLORIDA NEWBORN HYBRID COMPUTATIONAL DOSIMETRY PHANTOMS By Michael B. Wayson December 2009 Chair: Wesley Bolch Major: Nuclear Engineering Sciences A very important aspect of nuclear medicine imaging that is always in need of improvement is organ dosimetry. Since nuclear me dicine imaging is based on the biodistribution of an administered radiopharmaceutical, radiation is emitted from the set of organs to which the radiopharmaceutical localizes. The determinatio n of tissue absorbed dose from radiations emitted from inside the human body is known as internal dosimetry and is an integral part of performing risk assessment for nuclear medicine imaging. Computational radiation dosimetry is typically performed for such procedures owing to the difficulties of using physical phantoms and dose measuring devices for organ dose assessment. This study discusses the recent advancemen ts in computational dosimetry methods, develops an improved method of determining dose to the human skeleton from incident photons, and calculates a new comprehensive set of photon specific absorbed fracti ons for the University of Florida newborn hybrid phantoms for use in inte rnal dosimetry estimates. The set of specific absorbed fractions can be used to calculate th e effective dose for any nuclear medicine imaging procedure, provided the radiopharmaceutical biok inetics and radionuclide decay information are known. 11

PAGE 12

12 Accurate dosimetry is needed in nuclear medicine imagi ng for the purpose of reducing patient risk and developing secondary cancer risk models. The results of this study provide the latest improvement in photon specific absorbed fractions and will be extended to the complete University of Florida hybrid computati onal phantom series in the future.

PAGE 13

CHAPTER 1 INTRODUCTION Our goal is to ensure that all children receive safe, quality care when they undergo medical imaging examinations (1). This statement was made by Marilyn Goske, M.D., chair of the Alliance for Radiation Safety in Pediatric Imaging in a press rel ease honoring the Alliance for their Image Gently campaign initiative. The Alliance was founded by the Society for Pediatric Radiology, the American Society of Radiologic Technologists, the American College of Radiology, and the American Association of Physicists in Medicine. The Image Gently campaign was created to educate radiologic tech nologists, medical physicists, radiologists, pediatricians, and parents about the radiation dose to children during computed tomography (CT) exams (1). Recently, the Alliance has created a ne w campaign that emphasizes radiation dose considerations during fluoroscopic procedures called Step Lightly (2 ). It has been shown that children are at a higher risk of expressing radiation induced effects later in life than adults from medical procedures i nvolving radiation (3). This is explained by the fact that children are inherently more sensitive to ra diation because their bodies are s till developing along with the fact that children have a much longer time to express radiation induced effects. These observations lead to the conclusion of great importance that radiation dose to children must be minimized for any given medical diagnostic procedure. While the Image Gently and Step Lightly campaigns emphasize minimizing radiation dose in CT and fluoroscopic imaging, they underscore the fact that radiation dose must be minimized for any medical procedure that involves ionizing radiation, including the imaging method of emphasis in this study: nuclear medicine. Background Occupational dosimetry in the clinical envi ronment is typically assessed by way of physical dosimeters. Usually, thermoluminescen t dosimeters (TLDs) are used to record an 13

PAGE 14

integral dose for medical workers whose duties include working with radiation. The TLDs are then analyzed and the integral radiation dose is recorded for that worker. While this works well for determining occupational exposures, the pa tient undergoing a medical procedure involving radiation does not receive a physic al dosimeter to determine the absorbed dose to the patient. This is due in large part to the difficult logist ics and cost of individually analyzing TLDs for every patient for every exam, which is simply impractical. Because of the logistical difficulty of utilizing physical dosimeters fo r everyday medical dosimetry, me thods of determining patient dose have been investigat ed extensively over the years. Accu rately calculating radiation dose to a patient is an important and generally missing st ep in the medical examination of the patient. Quantifying radiation dose is es sential for the purpose of assessing risk of effects resulting from radiation exposure. Studies performed on th e Japanese atomic bomb survivors showed that an increase in radiation exposure led to an increase in excess cancer mortality for the study population ( 4). The result of that study made it clear that excessive exposure to radiation is detrimental to the human body. While comprehensiv e studies of cancer risk associated with low doses of radiation have not been conducted thus far, the mechanisms for increased cancer risk from any exposure to radiati on can be explained. As a basic example, the mechanism for incr eased cancer risk from the absorption of electromagnetic radiation (phot on) will be explained. The incident photon interacts with molecules within a cell in human tissue. Th rough either photoelectric or Compton scattering interactions, an electron is liberat ed by the photon. This forms a fr ee radical which is an atom or molecule that possesses an unpaired orbital electron in the outer shell ( 4 ). For example, an interaction with a water molecu le could produce the reaction H2O H2O+ + e-, where the water molecule is ionized and an electron is liberate d. The water ion radical then interacts with a 14

PAGE 15

second water molecule, producing the reaction H2O+ + H2O H3O+ + OH, where OH is a highly reactive product known as the hydroxyl radical ( 4). The hydroxyl radical then interacts with DNA to create a DNA radical which can lead to DNA strand breaks. If the strand breaks are not repaired, DNA mutati on can occur and lead to the genesis of cancer. This is one example of how incident radiation, in this case, photons, ma y lead to cancer. It would follow, then, that any incident radiation is cause for concern. The pertinent application to medical imaging is that one must always attempt to minimize the radiation dose to the patient. Obviously, me dical imaging aims to procure an accurate diagnosis, so image quality is also a priority when administering an exam. There is a constant balance between radiation dose and image quality th at medical professionals must always keep in mind when examining their patients, but this is not always possible due to insufficient quantitative relationships between radiation dose and image qualit y. This optimization may only become a reality when the dosimetry performed for medical imaging is as accurate as possible. History of Computational Dosimetry Phantoms As previously discussed, physical dosimeters are not used for patients undergoing medical imaging procedures involving radi ation. Therefore, a different method of determining radiation dose was developed. This method involved the use of computational dosimetry phantoms. Computational dosimetry phantoms are virtual representations of humans which are then input into radiation transport codes to calculate radia tion dose from any defined radiation source. This is contrast to another type of dosimetry pha ntom: a physical dosimetry phantom. These are physical constructs made to model human anatom y, based on CT data, which are then integrated with physical dosimeters. It is not always optimal to utilize physical dosimetry phantoms because they cannot be easily modified once built. 15

PAGE 16

The computational dosimetry phantoms may be used to assess the absorbed radiation dose from a variety of radiation sources. Medical imag ing radiation sources incl ude external radiation beams employed in modalities such as genera l radiography, CT, or fl uoroscopy or internal sources such as nuclear medicine imaging modalities which encompasses positron emission tomography (PET) and single photon emission com puted tomography (SPECT). The emphasis of this study was the analys is of internal sources. An early attempt at creating a virtual representation of humans was described in the Society of Nuclear Medicines (SNM) Medical Internal Radi ation Dose (MIRD) committee pamphlet No. 3 in 1968. The MIRD committee tabul ated a set of photon absorbed fractions (AF) for an adult phantom which was comprised of a combination of simple mathematical shapes such as spheres, ellipsoids, and elliptical and right circular cylinders ( 5). Tissues of the human body were homogeneous in nature and included elements H, C, N, O, Cl, and Na ( 5). Computational dosimetry phantoms made up of simple mathema tical shapes are referred to as stylized phantoms. Another early model was developed by Oak Ridge National Laboratory (ORNL) in the early 1960s and was a whole body model created for the purpose of external beam dosimetry ( 6). This model attempted to represen t the trunk of an adult and was a simple right circular cylinder 30 cm in diameter and 60 cm in height. This early generation phantom can be seen in Figure 11. In the mid-1960s, ORNL developed a new styl ized adult phantom called the Fisher-Snyder Phantom. This model consisted of three distin ct regions: the head and neck, the trunk including arms, and the legs. The head and neck were de scribed by an elliptical cylinder, the trunk and arms also by an elliptical cylinder, and the legs by truncated elliptical cones ( 7). Some structures 16

PAGE 17

left out of this model include hands, feet, ear s, nose, lungs, or skeleton. All tissues were assumed to be homogeneous. The MIRD committee published in 1969 an advancement of the Fisher-Snyder adult phantom in their 5th pamphlet. The Fisher-Snyder phantom was a heterogeneous model of the adult and was officially called the MIRD Phantom ( 7). In this phantom, 22 internal organs were modeled by way of three dimensional surface equations. Three body tissues were modeled: skeletal tissue, lung tissue, and soft tissue. Photon AFs were calculated for 12 energies with a range of 25,000 to 50,000 histories for each calculation ( 7). The MIRD Phantom was later revised in 1978 with improvements in the orga n models and statistics. The number of photon histories was increased to 60,000 for each source organ ( 8). The revised MIRD 5 adult phantom can be seen in Figure 1-2. Development of pediatric models also took place in the 1970s at ORNL. Early attempts at pediatric models involved the simple down-scal ing of the adult MIRD Phantom. A newborn phantom along with 1-yr, 5-yr, 10-yr, and 15-yr phantoms were created in this fashion. Currently, the international standard for com putational dosimetry phantoms is the phantom model series created in 1980 by Mark Cristy and Keith Eckerman. These phantoms were a revision to the ORNL pediatric series of mode ls and can be seen in Figure 1-3. The key improvements of these models were new models of the heart, breasts, and thyroid and a new model for skeletal dosimetry usi ng dose-response functions (DRFs) ( 9). A complete set of specific absorbed fractions (SAF) were ca lculated for each of these phantoms. All of the previously described phantoms ar e stylized phantoms. That is, they are described by mathematical shapes. While this method of representing humans for the purpose of computational dosimetry is flexible and easy to use, it is not very anatomically realistic. A more 17

PAGE 18

anatomically realistic way of representing humans is to use actual anatomic data to create a computational phantom. This is done by using medical images of actual patients to create phantoms. For example, a CT image set of a pati ent may be segmented to yield almost an exact copy of the patient who was scanned. This data is then voxelized for use in radiation transport codes. The term voxelization refers to the proc ess of transforming a shape or combination of shapes into an equivalent conglomerate of rectan gular prisms. Frequently, the rectangular prisms are defined to have equal length si des, thereby forming a set of cubes. If these cubes are created at a fine enough resolution, the original shape can be faithfully represented. The phantoms created from original image sets were very anatomically realistic, but they were unable to be extended to a variety of applic ations due to their spec ific nature. A phantom created from a specific patients image set can only be accurately used for dosimetry on that patient because it is very difficu lt to adjust the size and position of a voxel phantom. Since the process of segmentation is so tedious, indivi dual voxel phantoms cannot be created for every patient who undergoes a medical image exam. In addition, some structures in the body such as the large and small intestines ar e virtually impossible to accurate ly segment on a CT or magnetic resonance (MR) image. One previous voxel phantom was the VIPMan, created using transverse color photographic images from the National Librar y of Medicines Visi ble Human Project ( 10). The subject was a recently executed 38 year old male from Texas. The resulting voxel model can be seen in Figure 1-4. Another example of pr evious voxel phantoms is the GSF voxel phantom family ( 11). This set of phantoms includes females of 8 weeks, 7 years, 26 years, and 40 years, males of 38 years, a second 38 year old, 48 y ears, and an unknown age, two physical phantoms 18

PAGE 19

representing a torso and head and the thorax, and one female standardized gastrointestinal tract. A representative set of this family of voxel phantoms can be seen in Figure 1-5. So, while voxel phantoms are preferred in term s of anatomic realism, they lack in flexibility of use. The reverse is true for styl ized phantoms. The draw backs of these respective options for computational radiation dosimetry n ecessitate a bridge between the stylized and voxel phantoms which would allow for anatomic realis m as well as flexibility of use. This study addresses that void and describes the recent advancement in computational dosimetry phantoms: hybrid dosimetry phantoms. Purpose of Study It is clear from the previous discussion that th ere is a need for accurate radiation dosimetry for patients undergoing medical imaging procedures involving radiation. This study addresses the advancements in computer modeling of humans that have been made at the University of Florida (UF) and the curr ent state of computation dosimetry phantoms. The study then presents a DRF model which potentially greatly improves th e state of skeletal dosimetry. Finally, a complete dosimetry characterization of the current UF newborn hybrid phantom will be presented. The dosimetry characterization enta ils a presentation of a complete set of photon SAFs for application to internal dosimetry. Th ese SAFs are paramount in accurately calculating absorbed dose to tissues of interest for any gi ven nuclear medicine procedure. The resultant absorbed doses to tissues of interest can then be used to calculate an effective whole body dose. The SAFs may also be extended to any situation where a human has either inhaled or ingested photon emitting radionuclides. Eventually, the SAFs fr om this study will be incorporated into a computer program which will allow the user to qu ickly and accurately assess the effective dose to any newborn patient undergoing a nuclear medicine procedure. This is one step in a line of many that will establish a new SAF dataset to be used for any patient from a newborn to an adult. 19

PAGE 20

The determination of dose for actual patients undergoing nuclear medicine procedures is useful for dose tracking and the eventual determin ation of radiation risk, but another application of dosimetry characterization involves the use of computa tional phantoms alone. Employing computational phantoms is an effective and sa fe way of optimizing diagnostic procedures. Injecting a particular patient with varying am ounts of radiopharmaceutical for PET imaging and measuring the subsequent image quality is not a safe way of optimizing the procedure. Instead, virtual patients would be used, thus sparing the dose to the patient. The application of the results of this study is very powerful and will provide insight into the safest way to image patients. A typical procedure performed on newborn patients was explored in this study and will be presented. A whole body dose estimate was calculated for a renal function imaging procedure to demonstr ate the ease and accuracy of application. One example of an application of the data re sulting from this study shows that dosimetry can be performed for any nuclear medicine imagi ng procedure. There is much work to be done to extend this analysis to the whole family of UF hybrid phantoms for both photon and electron dosimetry, but a comprehensive set of photon SAFs for the UF newborn hybrid phantom is a big step in the right direction. 20

PAGE 21

Figure 1-1. The first stylized model of the trunk of an adult human. A right circular cylinder 30 cm in diameter and 60 cm in height ( 6). 21

PAGE 22

A B Figure 1-2. The MIRD Pamphlet No. 5 revised stylized computational dosimetry phantom ( 9). A) Outer body contour. B) Anterior view of principle organs in head and trunk. Figure 1-3. The complete current ORNL styliz ed computational dosimetry phantoms series ( 9 ). 22

PAGE 23

A B Figure 1-4. The VIP-Man voxel phantom ( 10). A) Original image used for segmentation. B) Final VIP-Man voxel model. A B C D Figure 1-5. A representative set of voxel phant oms for the GSF family of voxel phantoms ( 11). A) Baby. B) Child. C) Adult female Donna. D) Adult male Golem. 23

PAGE 24

CHAPTER 2 MATERIALS AND METHODS UF Newborn Hybrid Dosimetry Phantom The computational dosimetry phantoms di scussed previously represent the 1st and 2nd generation phantoms. The simple stylized phan toms based on mathematical functions were the 1st generation phantoms. The medical image-based voxel phantoms were the 2nd generation phantoms. A 3rd generation phantom has recently emerged and has been progressed extensively at UF. This 3rd generation phantom combines the concepts of the 1st and 2nd generation phantoms to yield a new phantom which possesses both anatomical realism and flexibility of modification. A mathematical modeling technique commonly us ed for computer animation is called nonrational b-spline (NURBS) surfaces NURBS surfaces can model vi rtually any free-form shape, so they are very useful in modeling complicated volumes such as those found in the human body. They are both flexible and easily modifiable. Because of this, NURBS technology was selected as the primary tool to create a new generation of phantoms that display both anatomic realism and flexibility of use. Since this 3rd generation phantom is a sort of mix between stylized and voxel phantoms (as will be seen later), the 3rd generation phantom has been termed a hybrid phantom. The UF newborn hybrid phantom is an adva ncement of the previous UF newborn voxel phantom ( 12). The voxel model of the newborn was constructed from a CT scan of a 6 day old female ( 13). This scan was saved as a 512 x 512 x 485 da ta array with a slice thickness of 1 mm. At this slice thickne ss and data array size, the UF ne wborn voxel model was the highest resolution model at the time ( 13). Delineation of organs was th en performed using an in-house Interactive Data Language (IDL) (ITT Visualiz ation Solutions, Boulder, CO) code, and 66 24

PAGE 25

different anatomic regions were defined ( 13). The UF newborn voxel model can be seen in Figure 2-1. The software 3D-DOCTORTM (Able Software Corp., Lexington, MA) was used to convert the UF newborn voxel phantom into a polygon mesh geometry. The voxel phantom was imported into 3D-DOCTOR and individual organs were segmented using interactive segmentation tools ( 12 ). Once all organs of interest were segmented, the polygon mesh model was imported to RhinocerosTM (McNeel North America, Seattle, WA), a NURBS modeling software, to transform the polygon mesh geometry into a NURBS geometry. Seven distinct anatomic groups were defined and imported separately into Rhinoceros : the exterior body contour, the respiratory system, the alimentary system, the circulatory system, the urogenital system, other soft tissue organs, and the skeleton ( 12). The organs of interest were then converted to NURBS surfaces. A NURBS surfa ce is much easier to manipulate than a polygon mesh volume because NURBS surfaces are define d by a series of control points which can be individually manipulated in three dimensions Volumes bounded by NURBS surfaces can easily be scaled in one, two, or three dime nsions. In view of this, it was desired that as many organs as possible be modeled using NURBS surfaces. Conversion from a polygon mesh geometry or iginating from manual segmentation to a NURBS geometry was relatively simple, but severa l small organs and organs that were difficult to segment from the original CT data had to be defined in a different way. Small organs such as the eyes, lenses, ovaries, urinary bladder, breasts, pitu itary gland, and tonsils were modeled using stylistic NURBS-based models ( 12). The original shapes and positions of these organs were referenced from the CT data and faithfully followe d in the construction of stylistic representative shapes. The contents of walled organs such as th e heart, gall bladder, and urinary bladder were 25

PAGE 26

modeled by copying the organ wall and scaling inward ( 12). The esophagus, small intestine, colon, and rectum were unable to be segmented fro m the original CT data, so a three dimensional trace of the lumen centroid was approximated from the segmented UF newborn voxel phantom ( 12). This was not feasible for the small intestin e due to CT slice discon tinuity, so a stylistic model was created and approved by a pediatric radiologist ( 12 ). At this point, a newborn hybrid computati onal dosimetry phantom was completed, but the model represented the patient from which the orig inal CT data was obtained. This patient was not necessarily representative of the 50th percentile newborn. Therefore, the International Commission on Radiological Protec tions (ICRP) Publication 89 was utilized to adjust the UF newborn hybrid phantom to reflect a 50th percentile newborn ( 12). Once the finalized UF newborn hybrid phantom was created, it was voxelized for use in a radiation transport code, as will be discussed later. The process of taking the original UF newborn voxel phantom, processing it with the previous discussed met hods, and voxelizing it for use in a radiation transport code can be seen in Figure 2-2. Th e completed UF hybrid newborn female phantom can be seen in Figure 2-3. Subsegmented Skeleton Development In the first iteration of the UF newborn hybrid phantom, the skeleton was described by a homogeneous model. The homogeneous skeletal model was taken from the UF newborn voxel model and implemented by the use of a combin ation of NURBS and polygon mesh geometry. The output of the segmentation process and subsequent input into Rhinoceros is inherently in the polygon mesh format. Since many bone sites are una ble to be effectively modeled with NURBS surfaces, they are left in the polygon mesh format. However, the ribs were sometimes distorted due to the CT slice thickness, so the ribs were created stylistically by creating pipe shapes based on central tracks taken from the original polygon mesh rib cage model ( 14). This homogeneous 26

PAGE 27

skeletal model treated all bone sites as a uniform mixture of cortical bone, trabecular bone, active bone marrow, and inactive bone marrow. Considering the anatomical realism of the rest of the hybrid phantom, the skeleton was lacking in detail. The human skeleton consists of three distinct regions: the cortical bone, spongiosa region, and cartilage regions. The spongi osa region is made up of trab ecular bone (TB), active bone marrow (AM), and inactive bone marrow. The newborn, however, only possesses AM ( 14). To produce accurate skeletal dosimetry, an accura te skeletal model must be used, so the homogeneous skeletal model needed to be updated to include all regions of the human skeleton. The process of creating a multiple region skelet al model began with the segmentation of all bone sites from a set of whole-body cadaver CT data (14 ). This was done automatically by adjusting the lower bound of the thresholding window in 3D-DOCTOR to exclude cartilage ( 14). Application of this thresholding window allowed for automatic segmentation of the whole skeleton from every CT slice, creating a whole-b ody homogeneous skeletal model. This initial segmentation provided the outer contour of th e skeleton. Next, the cartilage was manually segmented and two distinct cartilage regions we re identified: bone-associated cartilage and nonbone-associated cartilage ( 14). The spongiosa region and associat ed sub-regions were then de lineated by the analysis of microCT images of selected bone sites (14). The sternum, occipital bone, 2nd right rib, 2nd left rib, L2-L5 vertebrae, T9-T12 vertebrae, C3-C7 vertebrae, T1-T5 vertebrae, T10-T12 vertebrae, L1-L5 vertebrae, 4th right rib, 4th left rib, and a portion of the ri ght iliac crest obtained from two specimens were imaged using microCT at an isotropic resolution of 30 m ( 14). The AM and TB within each bone site was automatically segmented by visual inspection of the image gradient magnitude ( 15). This technique separated the AM and TB and created a new binary 27

PAGE 28

image files. These files were then used to calculate the fraction of spongiosa occupied by trabeculae and the fraction occupied by AM. This was performed for every bone site. Skeletal tissue masses were then obtained us ing methods detailed in Deanna et al ( 14). A detailed model of the human skeleton incl uding the intricacies of the spongiosa cannot currently be modeled in a NURBS environmen t and voxelized to a re solution that would preserve the detail of the spongiosa because the mi crostructure of the spongiosa is too intricate and small in dimension. If a skeletal model including heterogeneous regions of AM and TB were voxelized at a resolution fine enough to preserve the detail of the model, the files created to perform radiation dosimetry would be much too la rge, and the computer time for the simulations would in turn be extended dramatically. So, while the previously discussed advancements in skeletal tissue modeling for the purpose of computational radiati on dosimetry produced extensive data characterizing the distribution of skeletal tissues, the results were not directly applicable to the NURBS phantom. However, the results did lay the groundwork for the development of skeletal dosimetry methods that would be incorporat ed in steps separate from the primary dosimetry simulations. While the AM a nd TB sub-regions of the spongiosa could not be explicitly modeled in Rhinoceros, the spongiosa itself was able to be modeled. So, the final heterogeneous skeletal m odel was visualized in Rhinocerous as a three region model with the regions being the cartilage, cort ical bone, and spongiosa. Exampl es of heterogeneous bone sites in Rhinoceros can be seen in Figure 2-4. The orange wi reframe regions are cartilage. The black wireframe regions are both cortical bone and sp ongiosa. Regions of spongiosa are the smaller volume, darker wireframe structures. Skeletal Photon Dose Response Functions Since the intricacies of the spongiosa were unable to be explicitly modeled in the NURBS/polygon mesh environment, another tech nique was used to incorporate the lost 28

PAGE 29

spongiosa detail into the phantom: the skeletal do se response function (DRF). A DRF allows for the pre-calculation of the absorbed dose of a pa rticular region per unit fluence, in this case regions of the skeleton. In other words, separate simulations were performed which were able to model much smaller volumes. The results of th ese simulations were then used in conjunction with the NURBS-based computational phantom so th at the skeletal micros tructure did not have to be explicitly modeled in Rhinoceros. First, the radiosensitive cells in skeletal ti ssue had to be identified. Much research has been done to determine this, a nd the radiosensi tive cells were found to be hematopoietic stem cells, osteoprogenitor cell s, and chondrocytes ( 16 ). The surrogate tissues for these radiosensitive cells were determined to be AM for hematopoi etic stem cells, total shallow marrow otherwise known as endosteum (TM50) for osteoprogenitor cells, and uno ssified cartilage for chondrocytes ( 16). The endosteal region of the spongiosa was defined as all bone marrow that was within 50 m of the TB surface ( 16 ). For the newborn, only AM is present, so TM50 and AM50 are equivalent. Photons that interact with tissu es liberate electrons, and thos e electrons then directly ionize the medium. The energy deposited in this pr ocess, divided by the to tal mass of the medium irradiated results in the calculated radiation absorbed dose. So, wh ile it is of great interest where the emitted photons are transported, the electrons lib erated by those photons must also be taken into account. Because of the small dimensions of the skeletal microstructure, secondary electron transport is a concern. This is due to the fact that electr ons liberated by high energy photons have ranges which are relatively large compared to the spacing of the trabeculae in the spongiosa. Accordingly, to properl y characterize the behavior of secondary electrons liberated in the skeleton, the AFs for different skeletal source-target combinati ons were calculated. 29

PAGE 30

The paired-image radiation tr ansport (PIRT) model was us ed in conjunction with the Electron-Gamma-Shower (EGSnrc) radiation tran sport code of the National Research Council Canada to calculate the skeletal AFs. The combined model allows for tracking of electrons within the microstructure of the spongiosa as well as the macrostructure of the UF newborn hybrid phantom homogeneous skeletal sites. The microstructure was described with voxels of 60 m isotropic resolution, and the m acrostructure was described with voxels ranging from isotropic resolutions of 50 m to 200 m ( 16). Skeletal AFs were calculated for photons incident on the spongiosa with energies rangi ng from 1 keV to 10 MeV ( 16). AM, TB volume, and CB volume were all simulated as source tissues, and AM and TM50 were simulated as target tissues. An in-house MATLAB code, multi_drf_fast.m was used to calculate the DRFs, based on the AFs of the two target tissues, AM and TM50, the elemental compositions of mineral bone (trabecular and cortical), active marrow, and cartilage, and the masses of both source and target regions. The code uses the formul ation of the DRF in Equation 2-1 (9): ii i ir r iST r T S TdTTTniTrr m m E rDS S S 0/, (2-1) where and are the masses of the source a nd target tissues, respectively, SmTmiSTTrr is the AF in target tissue from source tissue for electrons of energy TrSriTiSr / are the mass attenuation coefficients for source tissue where i represents the photoelectric ( ), Compton ( ), pair production ( ), and triplet production ( ) processes, Sr iirTTnSidT is the number of electrons with energies between and iTidTiT liberated in source tissue for interaction type i, and is the DRF relating the absorbed dose to target tissue to the incident fluence of photons with energy E on the spongiosa. SrTr/E rDT 30

PAGE 31

Kinetic energy released per unit mass (ker ma) calculations were also performed using the in-house MATLAB code by setting the AF to one for self-irradiation and to zero for cross fire for every bone site. The kerma approximation assumes that all of the energy of the liberated secondary electrons is locally deposited; none of the energy escapes into any adjacent regions. Thus, for a source region emitting electrons liberated by the incident photons, all of the electrons will be absorbed by that source region, resul ting in an AF of approximately one for the irradiation scenario of the sour ce and target regions being the sa me. Alternately, no electrons emitted from the source region will penetrate adjacent regions, so the AF for the irradiation geometry of the source and target regions not being the same is a pproximately zero. Computational Dosimetry Simulations The tool used for the calculation of the SAFs was Monte Carlo N-Particle eXtended Version 2.5 (MCNPX) which is a radiation transport code de veloped by Los Alamos National Laboratory and is written in Fortran 90. MCNPX is a thre e-dimensional, time-dependent computational environment that transports radi ation through geometries specified by the user. These geometries can be created by combinations of simple surfaces (planes or cylindrical shells) or macrobodies (cubes, spheres, ellipso ids, etc.). MCNP5 preceded MCNPX and was only able to understand geometries in the context of these simple shapes and surfaces. However, to utilize the complicated geometries of NURBS -based computational dosimetry phantoms, the phantoms had to be broken down into voxel arrays because neither MCNP5 nor MCNPX understand NURBS surfaces. In addition, MCNP5 was unable to understand voxel geometries, so MCNPX was selected as the co mputation tool. MCNPX is able to stochastically model the transport of radiation through any geometry by way of random number generation. Incoherent and coherent scattering, fluores cent emission after photoelectric absorption, and absorption in electron-positron pair production are all accounted for during photon transport (17). Angular 31

PAGE 32

deflection through multiple scattering events collisional energy loss, and production of secondary particles are all accounted for during electr on and positron transport (17). Before MCNPX was utilized for radiation tran sport, a useful geometry was created for MCNPX to read. The computational phantom in its original form is a NURBS-based phantom which can be manipulated in the three-dimensional modelling program Rhinoceros as previously discussed. Once the phantom was finalized in Rhinoceros, it was exported as a *.raw (raw triangles) file. An in-house MATLABTM (The Mathworks, Inc., Natick, MA) code, voxelizer6.m, was used to convert the NURBS model into a voxel model at an isotropic voxel resolution of 0.663 mm, selected based on the reference newborn skin thickness (14). The skin of the phantom is not present in the NURBS format, so an in-house IDL code, skingenerator.idl, was used to place skin on the voxel phantom, which is accomplished by adding a layer of voxels on the outer surface of the phantom. Axial, corona l, and sagittal views of the voxelized newborn female phantom can be seen in Figure 2-5. The binary file output from skingenerator.idl was input into a second in-house MATLAB code, GenLattice.m, which created the *.lat (lattice) file that MCNP X reads as the radiation transport geometry. The lattice f ile specifies, in raster style, th e organ tag associated with each voxel in the voxel matrix. In this way, MCNPX is able to tally energy deposition or particle fluence in any specified organ in the phantom. At this point, the phantom was ready for use in MCNPX. An excerpt of a lattice file can be seen in Appendix A. The detailed concept of SAF calculations will be described later, but for the purpose of the MCNPX simulations, it is necessa ry to understand that SAFs are calculated based on either photons or electrons emitted from a specific organ wh ich are then absorbed in another organ. To accomplish this in MCNPX, source files of the form *.src were generated using an in-house 32

PAGE 33

Visual Basic code, lymphcounter.vbp. The source files specify the voxel coordinates of the source organ as well as the corresponding sampli ng probability. For most source organs, the sampling probability is set to one, which is i ndicative of uniform source sampling. Uniform source sampling means that the source is homogeneously distributed throughout the source organ. This is accurate for all organs aside from AM and TB. AM a nd TB are special cases because detailed microstructure is not able to be created at the selected voxel resolution. As discussed previously, the detail ed microstucture was accounted fo r in the development of the skeletal DRFs. Even though the heterogeneous skeletal model is a vast improvement over the previous homogeneous skeletal m odel, the spongiosa region of th e skeleton is still homogeneous in the phantom that is input into MCNPX. Because of this if the spongiosa was uniformly sampled to create the AM source, regions of TB would also be sa mpled and incorrectly included. The same problem would occur if the spongiosa was uniformly sampled to create the TB source. To accurately sample regions of AM from th e homogeneous spongiosa model, the bone sitespecific source sampling probabilities were adjusted to reflect the AM mass distribution in the skeleton. Specifically, the bone site-specific AM and TB mass fr action was used as the source sampling probability. The same solution was utili zed to create the TB source. The AM mass fractions are explicitly shown in Table 2-1 and the TB mass fract ions were calculated from bone site-specific TB masse s in Table 2-2. Source files were created for all organs in the male and female newborn phantom, including a total boday cartilage source, with the only differing organs being the gender-specific organs. Three other organs that were different between the male and female were the residual soft tissue (RST) and the urinary bladder wall and urinary bladder contents. There was a slight difference in the RST volume due to the difference in volume of the gender-specific organs. The 33

PAGE 34

bladder was also slightly different between the male and female to make room for the genderspecific organs. A complete list of source tissues can be seen in Table 2-3. Target tissues were the same as the source tissue with a few exceptions : cortical and trabecular bone were not targets and bone endosteum was added as a target. At th is point, the source file could be successfully read by MCNPX. Excerpts of the liver and AM source files can be seen in Appendix A which demonstrate both uniform and non-uniform sampling probabilitie s, respectively. The volumes of every region in the body must be speci fied for input into MCNPX. Part of the output of voxelizer6.m was a complete listing of the number of voxels comprising each organ. The voxel count for each organ wa s multiplied by the voxel volume of (0.663 cm)3 to calculate the volume of each organ. The density of each organ was also specified in the input file. Densities of 1.02 g/cm3, 0.572 g/cm3, 1.65 g/cm3, 0.0012 g/cm3, 1.10 g/cm3, and 1.33 g/cm3 were used for soft tissue, lung tissue, cortical bone, air, cartilage, and spongiosa, respectively (12,14,18). The atomic composition for each of these materials was also sp ecified in the input file and can be seen in Table 3 (14,18). The mass of any organ was calculated by MCNPX based on the volume and density of that organ. The user must decide what metrics MC NPX must output before the photons are transported. MCNPX utilizes what are called t allies to create meaningful output from the code. The tally identifiers important to the de termination of SAFs were the F4, F6, and *F8 tallies. The tallies are specified for every organ that is deemed a target organ. The F4 tally tracks photon flux averaged over th e target of interest and is quoted in units of particles/cm2. This tally was utilized for de termining energy deposition in s pongiosa regions of the phantom. The results were used with the sk eletal DRFs to calculate the SA F of the total body skeleton. To facilitate this process, the fl ux across bone sites was tallied in energy bins corresponding to the 34

PAGE 35

energies at which the DRFs were evaluated. The F6 and *F8 tallies track energy deposition averaged over the target of in terest in units of MeV/g and en ergy deposition over the target of interest in units of MeV, respectively. These tally types were used in non-skeletal targets. The F6 tally assumes that all secondary electrons created by the incident photons are locally deposited. As previously discussed, this is the kerma approximation. This approximation is valid for photon energies that create relatively low ener gy secondary electrons with short ranges. For high energy photons, secondary electron escape becomes a factor, and the *F8 tally, which tracks secondary electrons, becomes necessary. *F8 tallies require more computer time than F6 tallies due to the fact that *F8 tallies track sec ondary electrons. This situation affords the ability to increase the number of photons started for F6 tall ies, thereby decr easing the uncer tainty in the results. A threshold photon energy of 100 keV was c hosen as a the point at which the F6 tally is abandoned in favor of the *F8 tally. At this point, the number of photons started was decreased from 108 to 107. This energy threshold was determined by comparing the SAFs of a liver source determined from both F6 and *F8 tallies at various energies. The difference between the results from the F6 and *F8 tallies at an energy of 100 keV was found to be ~1 % and was considered acceptable. It is important to note that all ta llies are normalized to the number of photons simulated. So, all tally result s are inherently in the primary unit of measurement per photon. There were a total of 61 source organs simula ted for the female phantom and a total of 63 source organs simulated for the male phantom at 21 photon energies rangi ng from 0.01 MeV to 4 MeV for both. From these combinations, 1281 input files were run for the female phantom and 1323 input files for the male phantom for a total of 2604 input files. Due to the number of input files required for a complete dosimetry ch aracterization of both newborn phantoms, a MATLAB code, GenerateInput.m, was created to automatically gene rate each input file. The code 35

PAGE 36

generates an input file template that cycles through ever y photon energy for every source organ and changes the lattice file name, particle importances, simulation mode, tally type, and number of photons started based on the photon energy. If the photon energy is below 100 keV, the lattice file name is changed to one which only recogn izes photon transport, the photon importance is changed to one and the electron importance is changed to zero because only photons, not secondary electrons, are recognized below 100 keV, the mode is changed to photon transport only, the tally type is switched to F6 as previous ly discussed, and the numbe r of particles is set to 108. If the photon energy is above 100 keV, the lattice file name is changed to one which recognizes both photon and secondary electron transport, both the photon and electron importances are set to one becau se secondary electrons are tracked in addition to photons, the mode is changed to photon and electr on transport, the tally type is switched to *F8 as previously discussed, and the number of particles is set to 107. A sample input file for the female newborn phantom at a photon energy of 4 MeV for a liv er source can be seen in Appendix A. The ALRADS computer cluster possesses 56 us eable processors, so the large number of input files were able to be divided up and run on many processors. The average compter time for both phantoms was calculated and found to be a bout 12 hours with a tota l computer time of about 31248 hours, or 3.6 years. Distributed among many processors, the actual computer time was about 6 weeks. A post-processing MATLAB code, ParseOutput.m, was written to extract the tallies, convert them to SAFs, a nd place the results into Microsoft Ex cel files. This code for the female phantom can be found in Appendix B. Internal Dosimetry Formulation The computational dosimetry phantoms were used to calculate a set of SAFs at various photon energies. The SAF is an important measure which reflects the geometry of the irradiation scenario as well as the photon energy. It is ul timately used to calculate either individual organ 36

PAGE 37

absorbed doses, individual organ equivalent doses, or a whole-body effective dose. Dosimetry of internal emitters is derived from the em ission of radiation from any source tissue and the absorption of that radiation in target tissue For any target tissue, the time independent formulation of radiation absorbed dose from a se t of arbitrary source tissues emitting radiation is described by Equations 2-2 and 2-3 (19): SrTr S Sr STS r ST S TrrSrArrSdttrA rD ~ ,0 (2-2) i STi i T STii STrr m rrYE rrS (2-3) where srA ~ is the time-integrated activity or the total number of nuclear transformations occurring in source tissue is the radionuclide S value, defined as the mean absorbed dose rate to target tissue per unit activity in source tissue is the energy of the ith radiation, is the yield of the ith radiation, SrSTrrS TrSriEiY STrr is the AF, defined as the fraction of radiation energy emitted in source tissue that is absorbed in target tissue is the mass of the target tissue is the delta value for the ith radiation, defined as the product of the energy and the yield of the ith radiation, and SrTrTmTri SrTr is the SAF, defined as the ratio of the AF to the target tissue mass. As discussed previously, the values extracted from the output of the MCNPX simulations were energy deposition per unit ma ss averaged over the target tis sue for the F6 tally and total energy deposition over the target tissue for the *F8 tally. The unit for the F6 tally was MeV/g, so to obtain the SAF for any partic ular target tissue, the F6 tally result was divided by the initial photon energy. This method was determined to be accurate because the F6 tally described the amount of energy deposited in the target tissu e per unit mass by a single photon emitted in the 37

PAGE 38

source tissue. The deposited energy divided by the emitted energy determined the fraction of that emitted energy that was deposited in the targ et tissue which is, by definition, the AF. The SAF is defined as the AF divided by the mass of th e target tissue, giving units of inverse mass. Due to the small size of the newborn, it was prudent to evaluate the SAFs in units of g-1. To determine the SAF from the *F8 tallies, the *F8 result was divided by both the initial energy of the photon as well as the calculated mass of the target organ. This was determined to be accurate by the same reasoning as the F6 ta lly conversion except th at the total energy deposited needed to be divided by the total mass of the target tissue to obtain the same original units as the F6 tally. A different method was used to convert the spongiosa F4 tallies to AM and TM50 SAFs because the skeletal DRFs were used instead of direct dose or energy tallying. Equation 2-4 was used to calculate the SAFs for both AM and AM50 target regions for the whole skeleton: sp Tspri issp i T r STErr E rD w E k rr ,0 (2-4) where k is a constant that converts to units of g-1 and was found to be 6.24142 x 1013 cm2 MeV kg / m2 J g, is the initial photon energy, is the mass fraction of the target tissue in each bone site, 0ETsprwTr i TEr D is the skeletal DRF for target tissue (either whole body AM or AM50) at photon energy TriE isspErr is the photon fluence emitted from source tissue incident on the spongiosa of the bone si te of interest for photons of energy and SrS iETrr is the SAF for target tissue from any source tissue The computational MATLAB code, drfread.m developed for Equation 2-4 can be seen in Appendix B. TrSr SAFs were obtained for ever y source-target-energy combination for both the male and female UF newborn hybrid phantoms. This was deemed a complete set of photon SAFs and thus a complete internal photon dosimetry characteri zation of the UF newborn hybrid phantoms. 38

PAGE 39

These SAFs can be used to perform dosimetry calculations for any nuclear medicine procedure, provided the radiopharmaceutical biokinetics are known. Renal Function Case Study Once the dosimetry characterization was completed for the phantoms, it was desired that an application of the new dosimetry be explored. A nuclear medici ne imaging procedure typically performed on newborns is one that attempts to assess the renal function, or in the case of newborns, renal function immaturity: t echnetium-99m-dimercaptosuccinic acid (99mTcDMSA) SPECT ( 20). This study attempted to provide a dose estimate for a newborn patient for typical parameters used in the performance of this rena l function SPECT procedure. Clinical Aspects Two general groups of radiopharmaceuticals us ed in nuclear medicine imaging of the kidneys are those that quickly clear the kidne ys and those that accumulate in the renal parenchyma for a relatively long time ( 20). Quickly clearing radiopha rmaceuticals are used for the assessment of renal function and urine drainage, while slowly clearing radiopharmaceuticals are used for mapping of regional functioning renal parenchyma ( 20). Static renal scintigraphy performed using SPECT is the preferred method for renal function because of the ability to explore the kidney images in three dimensions. This is preferred ove r conventional planar scintigraphy because the planar method is not able to map regional functioning renal parenchyma. The procedure is performed using the radiopharmaceutical 99mTc-DMSA. The patient is injected with the radiopharmaceutical and instru cted to wait approximately 4 hours in order to allow the radionuclide to decay. The patient is then scanned using a three-detector array of gamma cameras. Scan times range from about 15 to 20 minutes to acquire approximately 120 images on a 128 x 128 pixel matrix ( 20). 39

PAGE 40

Dosimetry Assessment Biokinetics The first analysis performed in order to accu rately determine a whole-body effective dose was the characterization of 99mTc-DMSA biokinetics. Residence times, which take into account both radioactive and biological half-lives were calculat ed for each organ that retains the radiopharmaceutical, considered source organs, as described by rest SrA ~ in Equation 2-2. SrA ~ is in units of total number of nuclear transformations in source tissue This was defined as the administered activity multiplied by for each source organ. The source organs were determined to be the left and right kidneys (the kidney cortex was assumed to receive all of the kidney activity), liver, spleen, urinary bladder contents, heart c ontents, lungs, and rest of body ( 21, 22, 23). The biodistribution parameters for the newborn can be seen in Table 2-4 ( 21, 23). Blood kinetics were analyzed separately to ob tain lung and heart contents residence times. Srrest From the information in Table 2-4 as well as additional information not reported here, residence times were calculated based on Equations 2-2 and 2-5 ( 24): t t mpeeAtA 1 (2-5) where Am is fractional maximum uptake, Ao is fractional initial uptake, + is the uptake rate in h-1, is the clearance rate in h-1, effis the effective clearance rate in h-1, and is the time dependent fractional injected activity. Equation 2-5 was integrated from zero to infinity to obtain the organ specific radiopharm aceutical residence times, as indicated in Equation 2-2. Detailed biokinetic analysis was beyond the scope of this study, so the biokinetic calculations were simply patterned after a prev ious execution of this analysis ( 22 ). tA 40

PAGE 41

Whole-body effective dose Once the source organ residence times were obt ained, individual e quivalent organ doses were determined as well as a whole-body effective dose. Dose calculations were normalized to the injected activity to facil itate the comparison between dos e calculations based on the UF newborn hybrid phantom and a pr evious study using stylized phantom. The formalism for calculating organ and whole body absorbed dose ha s already been described by Equations 2-3 and 2-4. Individual organ equivalent doses we re determined by Equation 2-6, and the whole body effective dose was calcula ted using Equation 2-7 ( 25): (2-6) R RrR rT TDwH, (2-7) T TTr rrHwEwhere is the radiation weighting factor for radiation type R is the organ weighting factor for target organ is the absorbed dose to target organ from radiation type R in units of mGy / MBq, is the organ specific equivalent dose in units of mSv / MBq, and E is the whole body effective dose in units of mSv / MBq. RwTrwTrTr RrTD,TrH The radiation weighting factor is based on th e linear energy transfer (LET) characteristics of the incident radiation type. For photons, the radiation weighting factor is one, so the organ specific equivalent dose is equal to the absorbed dose. The organ weighting factors are based on radiation stochastic risk data and takes into account lifetime cancer incide nce, dose and dose-rate effectiveness, lethality, quali ty of life for non-fatal cancers, and years of life lost ( 25). The study used for comparison utilized the tissue wei ghting factors recommended by ICRP 30, so for consistency these values were used despite the fa ct that more recent tissue weighting factors have been developed ( 20). 41

PAGE 42

Tc-99m has a radioactive half-life of 6. 02 hours and decays primarily by isomeric transition with a principal gamma-ray energy of 140.5 keV and yield of 0.8906 at this energy ( 26). The SAF was obtained by interpolation between 0.1 and 0.15 MeV. By applying the gamma-ray energy, radiation yield, source organ residence times, radiation weighting factor, target organ weighting factors, and energyand organ-dependent SAFs, the individual organ equivalent doses and whole-body effective dose were obtained. The application of the methods described for the dosimetry of the renal function case study yields the photon component of the whole-body effective dose. To compare the results to a previous determination of organ equivalent do ses and whole-body effective dose, an estimate of the electron component of the absorbed dose must be made. As a rough estimate, the absorbed fractions for electrons were set to one when the source and target tissues were the same and zero when the source and target tissues were different. Delta values were used to convert the SAFs calculate for the electrons to radionuclide S va lues, which were then converted to normalized dose by multiplying by the residence times in each s ource organ. The delta values, in units of Gy kg / nuclear transformation, were obtained from the latest MIRD series of radioactive decay data for -, internal conversion, and A uger electrons. Obviously, an estimate of electron dose does not generate the most accurate estimate of organ equivalent or whole-body effective dose, but the purpose of the re nal function case study was to demonstrate the ease of application to a real world situation rather than provide ex act dose calculations for renal function SPECT imaging. 42

PAGE 43

Table 2-1. Active marrow distribution in the UF newborn hybrid phantom compared to active marrow distribution for the refe rence newborn in ICRP 89 ( 14). 43

PAGE 44

Table 2-2. Mineral bone (trab ecular and cortical bone) distribu tion in the UF newborn hybrid phantoms ( 14). 44

PAGE 45

Table 2-3. A list of all the source organs for the male and female UF newborn hybrid phantoms. Residual soft tissueLarynx Spleen Adrenal (L) Lens Stomach wall Adrenal (R) Liver Stomach contents Brain Lung (L) Testes Breast Lung (R) Thymus Bronchi Nasal layer (anterior)Thyroid Right colon wallNasal layer (posterior)Tongue Right colon contentsOral cavity layerTonsil Ears Ovaries Trachea Esophagus Pancreas Urinary bladder wall External nosePenis Urinary bladder contents Eye balls Pharynx Uterus Gall bladder wallProstate Air (in body) Gall bladder contentsPituitary gland Left colon wall Heart wall Rectosigmoid wallLeft colon contents Heart contentsRectosigmoid contentsSalivary glands (submaxillary) Kidney-cortex (L)Salivary glands (parotid)Salivary glands (sublingual) Kidney-cortex (R)Scrotum Cartilage Kidney-medulla (L)Small intestine wallActive marrow Kidney-medulla (R)Small intestine contentsTrabecular bone Kidney-pelvis (L)Skin Cortical bone Kidney-pelvis (R)Spinal cord Table 2-4. Biokinetic parameters for 99mTc-DMSA for the newborn patient (22)*. AmAo+ (h-1) (h-1) eff(h-1) 6 h24 h Left kidney 0.21--0.720.009-----Right kidney 0.21--0.640.008-----Liver --0.057----0.14---Spleen --0.016----0.16---Urinary bladder contents----------0.0660.13 Whole body ----------Fraction Excrete d *Am is fractional maximum uptake, Ao is fractional initial uptake, + is the uptake rate, is the clearance rate, and effis the effective clearance rate. 45

PAGE 46

A B C Figure 2-1. Coronal and sagi ttal views of the UF newborn voxel computational dosimetry phantom ( 13). A) Outer body contour. B) Skel eton. C) Principal internal organs. 46

PAGE 47

A B C D E Figure 2-2. Steps in the process of converti ng the original newborn voxel model into a NURBS model and voxelizing for input into MCNPX ( 12 ). A) Original voxel geometry. B) Polygon mesh geometry. C) NURBS geometry. D) Voxelization of NURBS volume at (2 mm)3 resolution. E) Voxelizati on of NURBS volume at (1 mm)3 resolution. A B C Figure 2-3. The UF newborn hybrid female phantom. A) Coronal view B) Sagittal view. C) Perspective view. 47

PAGE 48

A B C D Figure 2-4. Sample bone sites of the UF newbor n hybrid phantom heterogeneous skeleton. A) Hand. B) Right Humerus. C) Pelvis. D) L-spine. A B C Figure 2-5. UF newborn hybrid female phant om voxelized at a reso lution of (0.663 mm)3. A) Axial view. B) Coronal vi ew. C) Sagittal view. 48

PAGE 49

CHAPTER 3 RESULTS Skeletal Dose Response Functions A representative bone site to di splay the results from the DRF analysis was chosen to be the mandible, and the DRFs and kerma response f unctions for the mandible can be seen in Figure 3-1. The results were shown with units of absorbed dose per unit photon fluence or Gy m2 / photon. As shown in Equation 2-4, a unit conversi on factor was needed to convert the original DRF units to the final desired SAF units of g-1. Examining first the DRF calculated for the AM target, it should be noted that the source was total spongiosa which was comprised of both AM and TB. The dose response was assessed for a fluence of photons incident on the spongiosa. In turn, the electrons liberated in both AM and TB were considered the source. Also note that the total AM region includes the TM50, but not vice versa. The AM DRF originates at a value just below 10-15 Gy m2 / photon for a low photon energy of 0.01 MeV. This was due to the fact that the resultan t secondary electrons, initiated at a comparable low energy, possessed ve ry short ranges and thus primarily deposited most of their energy at the site in which they were born. As the incident photon energy increases to about 90 keV, the DRF declines because the el ectrons begin to attain energies capable of transporting them into nearby trabeculae, thus de livering less dose to the AM. As the incident photon energy increases past 90 keV, the DRF incr eases because the seco ndary electrons have enough energy to penetrate completely through the trabeculae and into adjacent regions of AM. At high energies greater than 1 MeV, the DRF begins to decline because the DRF calculations were based on AF data which assumed that all in itiated electrons attain enough energy to mostly escape from the spongiosa in to the cortical bone ( 16). However, as will be discussed later, this model was not the most accurate. 49

PAGE 50

The shape of the TM50 (bone endosteum) DRF can be explained in the same way as the AM DRF. However, it is ev ident that at inte rmediate incident photon energies, the TM50 DRF is slightly greater than the AM DRF. This is because as in cident photon energy increases the secondary electrons that escape th e TB regions terminate in the AM50 before they attain enough energy to penetrate through the TM50 region into the AM region. While the above discussion of the results of the DRF analysis describes some of the physics taking place, the shapes of the curves cannot be described completely in this manner. The DRFs are heavily dependent on the shape of the energyand atomic composition-dependent photon interaction cross sections. Th is is evidenced by Equation 2-1. As previously noted, the DRFs were cal culated based on AF data which assumed secondary electron escape from th e spongiosa into the surrounding co rtical bone. However, this model did not take into account secondary el ectrons born in the su rrounding cortical bone entering the spongiosa. At high en ough incident photon energies, this is the case, and it creates a sort of charged particle equilibrium (CPE). In this CPE scenario, electrons escaping a particular microstructure are replaced by el ectrons entering the microstruc ture from the cortical bone. Physically, this process can be represented by ignoring the DRF consider ing escape and thinking of the secondary electrons as depositing all of thei r initiated energy at the site of interaction. Kerma describes this physical process exactly. Therefore, it was decided that the calculated DRFs would be accepted up until the point at whic h the DRFs began to deviate from the kerma response functions. At this deviation point, th e DRFs were cut off and replaced by the results from the kerma response functions, forming a sort of hybrid DRF. It can be seen that there is a slight difference between the kerma response for spongiosa and the kerma response for AM. The kerma response for spongiosa was chosen to comp lete the skeletal DRFs because there is no 50

PAGE 51

microstructure present in the dosimetry phantoms. The spongiosa region was the only region that was able to be tallied for photon fluence. The complete hybrid DRF results can be seen in Figure 3-2. Specific Absorbed Fractions A representative source tissue was selected to display the results of the SAF calculations, and this source tissue was chosen to be the live r of the UF newborn female hybrid phantom. The SAFs for the liver source can be seen in Table 3-1. A plot of the SAFs for selected target organs can be seen in Figure 3-3. The average error over all target organs and energies was ~1%, which was considered acceptable. Similar errors were seen across all source-target-energy combinations. The purpose of this section is to simply presen t the results. The results will be compared to SAFs obtained for the newborn stylized phantom by ORNL in the next section. It will be seen that there were notable differences between the SAFs found from the UF newborn hybrid phantom and the ORNL new born stylized phantom. Renal Function Case Study The residence times calculated from the newborn patient biokinetic data for 99mTc-DMSA can be seen in Table 3-2. These residence ti mes were used to calcula te the photon and electron components of the organ equivalent doses and those results can be seen in Table 3-3 along with the associated tissue weighting factors for each target organ. Using Table 3-3, a whole-body effective dose of 1.63 x 10-1 mSv / MBq was calculated for the UF newborn female hybrid phantom using the ICRP 30 tissue weighting factors and 7.52 x 10-2 mSv / MBq using the ICRP 103 tissue weighting factors. Tc-99m-DMSA is us ually given with a dose of 1.5 to 1.9 MBq / kg ( 20). For the UF newborn female hybrid phantom, whose total mass was ~3.5 kg, a typical whole-body effective dose was found to be betw een 0.84 and 1.06 mSv for the ICRP 30 tissue 51

PAGE 52

weighting factors and 0.39 and 0.49 mSv for th e ICRP 103 tissue weighting factors. For comparison, a years dose of natural background radiation is about 1 mSv. 52

PAGE 53

Table 3-1. Specific absorbed fractions in units of g-1 for the liver source in the female UF newborn hybrid phantom. Source = Liver Target 0.010.0150.020.03 0.040.050.060.080.1 Residual Soft Tissue 2.76E-057.00E-051.11E-041. 25E-049.84E-057.59E-056. 22E-054.98E-054.58E-05 Adrenal (L) 1.66E-081.72E-051.22E-042.54E-0 42.22E-041.76E-041.44E-041.14E-041.03E-04 Adrenal (R) 1.01E-045.60E-049.55E-048.55E-0 45.72E-044.06E-043.19E-042.47E-042.25E-04 Brain 0.00E+001.89E-115.52E-096.68E-072.15E-062.88E-063.10E-063.12E-063.13E-06 Breast 0.00E+002.80E-063.45E-059.94E-059.23E-057.35E-056.18E-055.07E-054.71E-05 Bronchi 0.00E+009.85E-069.14E-051.95E-041.68E-041.32E-041.08E-048.50E-057.67E-05 Right Colon W 5.53E-051.90E-043.23E-043.47E-0 42.56E-041.89E-041.51E-041.18E-041.07E-04 Right Colon C 1.62E-051.39E-042.88E-043.34E-0 42.50E-041.85E-041.48E-041.16E-041.05E-04 Ears 0.00E+000.00E+001.98E-073.50E-065. 84E-066.13E-065.95E-065.53E-065.45E-06 Esophagus 1.53E-051.51E-043.17E-043.49E-042.56E-041.90E-041.53E-041.19E-041.08E-04 External nose 0.00E+001.51E-073.41E-061.45E-0 51.54E-051.34E-051.20E-051.04E-051.00E-05 Eye balls 0.00E+000.00E+001.22E-072.59E-065 .41E-066.21E-066.23E-065.96E-065.88E-06 Gall Bladder W 2.18E-041.04E-031.58E-031.26E-0 38.08E-045.61E-044.36E-043.36E-043.06E-04 Gall Bladder C 1.00E-048.75E-041.50E-031.25E-0 38.04E-045.59E-044.34E-043.34E-043.05E-04 Heart W 6.44E-052.88E-045.14E-045.09E-043 .58E-042.59E-042.05E-041.59E-041.45E-04 Heart C 6.59E-061.60E-044.22E-044.86E-043 .52E-042.57E-042.04E-041.58E-041.43E-04 Kidney-cortex (L) 0.00E+008.54E-072.21E-059.65E -051.03E-048.87E-057.54E-056.07E-055.49E-05 Kidney-cortex (R) 6.45E-053.88E-046.53E-045.92E-044.05E-042.91E-042.30E-041.78E-041.63E-04 Kidney-medulla (L) 0.00E+006.91E-072.27E-051.03E -041.10E-049.42E-058.00E-056.42E-055.78E-05 Kidney-medulla (R) 5.09E-062.03E-044.95E-045.29E -043.77E-042.74E-042.17E-041.68E-041.53E-04 Kidney-pelvis (L) 0.00E+004.03E-071.98E-059.83E -051.07E-049.19E-057.85E-056.30E-055.69E-05 Kidney-pelvis (R) 5.75E-071.18E -043.80E-044.62E-043.41E-042. 51E-042.00E-041.55E-041.40E-04 Larynx 0.00E+003.41E-082.42E-062.37E-053.19E-053.02E-052.70E-052.28E-052.10E-05 Lens 0.00E+000.00E+003.75E-073.48E-065.80E-066.36E-066.15E-065.79E-065.73E-06 Liver 7.33E-036.19E-034.67E-032.36E-031. 32E-038.75E-046.72E-045.25E-044.90E-04 Lung (L) 1.66E-059.06E-051.92E-042.46E-041 .94E-041.47E-041.17E-048.98E-058.00E-05 Lung (R) 5.14E-052.96E-045.32E-045.20E-043 .61E-042.58E-042.01E-041.52E-041.36E-04 Nasal layer (anterior) 0.00E+001.32E-073.80E-061. 56E-051.63E-051.40E-051. 26E-051.08E-051.03E-05 Nasal layer (posterior) 0.00E+006.15E-091.93E-073 .66E-067.04E-067.81E-067 .72E-067.28E-067.09E-06 Oral cavity layer 0.00E+004.52E-091.10E-061.49E -052.17E-052.12E-051.92E-051.66E-051.55E-05 Ovaries 0.00E+001.99E-077.02E-064.43E-055 .42E-054.94E-054.28E-053.54E-053.19E-05 Pancreas 0.00E+008.56E-067.99E-051.93E-041 .74E-041.39E-041.15E-049.00E-058.08E-05 Pharynx 0.00E+000.00E+004.64E-079.47E-061 .57E-051.62E-051.51E-051.34E-051.25E-05 Pituitary Gland 0.00E+000.00E+000.00E+008.40E -073.28E-064.58E-064.96E-065.09E-064.96E-06 Rectosigmoid W 0.00E+003.19E-076.55E-063.63E -054.48E-054.14E-053.65E-053.04E-052.77E-05 Rectosigmoid C 0.00E+002.82E-076.34E-063.73E -054.63E-054.27E-053.76E-053.13E-052.85E-05 Salivary Glands (parotid) 0.00E+005.69E-094.83E-0 79.21E-061.49E-051.52E-051 .42E-051.25E-051.18E-05 SI W 2.01E-057.04E-051.41E-041.94E-041. 61E-041.26E-041.03E-048.11E-057.32E-05 SI C 6.69E-065.48E-051.31E-041.91E-041. 60E-041.25E-041.02E-048.07E-057.28E-05 Skin 6.93E-086.79E-062.84E-055.15E-054. 53E-053.66E-053.07E-052.54E-052.38E-05 Spinal Cord 0.00E+003.11E-063.46E-051.16E-0 41.19E-041.01E-048.64E-057.09E-056.54E-05 Spleen 1.42E-081.33E-059.01E-051.92E-041. 69E-041.34E-041.10E-048.72E-057.87E-05 Stomach W 7.86E-052.98E-045.15E-045.30E-043 .81E-042.79E-042.21E-041.71E-041.55E-04 Stomach C 1.43E-051.71E-044.09E-044.83E-043 .58E-042.64E-042.11E-041.63E-041.47E-04 Thymus 0.00E+002.08E-063.43E-051.09E-041.05E-048.66E-057.24E-055.77E-055.23E-05 Thyroid 0.00E+002.50E-083.51E-062.95E-053 .80E-053.51E-053.12E-052.61E-052.39E-05 Tongue 0.00E+006.15E-091.32E-061.68E-052. 39E-052.31E-052.08E-051.79E-051.66E-05 Tonsil 0.00E+000.00E+007.28E-071.23E-051. 97E-051.94E-051.80E-051.54E-051.44E-05 Trachea 0.00E+009.63E-071.98E-057.56E-057.80E-056.63E-055.64E-054.56E-054.12E-05 Urinary bladder W 0.00E+001.42E-081.33E-061.64E -052.40E-052.34E-052.13E-051.81E-051.68E-05 Urinary bladder C 0.00E+006.52E-091.17E-061.55E -052.31E-052.26E-052.07E-051.77E-051.63E-05 Uterus 0.00E+002.10E-082.23E-062.36E-053. 29E-053.13E-052.82E-052.38E-052.18E-05 Air (in body) 1.78E-041.85E-028.54E-021.68E-0 11.50E-011.21E-011.00E-018.08E-027.46E-02 Left Colon W 2.67E-086.21E-064.01E-051.04E-0 41.00E-048.26E-056.91E-055.53E-055.00E-05 Left Colon C 1.02E-084.97E-063.73E-051.02E-0 49.93E-058.23E-056.90E-055.50E-054.98E-05 Salivary Glands (submaxillary)0.00E+000.00E+001.62E -061.79E-052.50E-052.37E-0 52.13E-051.82E-051.70E-05 Salivary Glands (sublingual)0.00E+001.76E-083.26E-0 62.45E-053.06E-052.79E-052 .48E-052.09E-051.93E-05 Cartilage 1.07E-097.53E-091.78E-083.05E-083 .16E-082.97E-082.83E-082.83E-083.10E-08 Active Marrow (AM) 1.63E-061.30E-053.54E-056.42E -056.33E-055.69E-055.09E-054.36E-053.98E-05 Endosteum (AM50) 1.58E-061.28E-053.55E-056.75E-056.91E-056.28E-055.60E-054.60E-054.04E-05 Energy (MeV) 53

PAGE 54

Table 3-1. Continued. 0.150.20.30.40.50.60.811.5234 4.47E-054.56E-054.70E-054.75E-054 .75E-054.71E-054.60E-054.47E-054 .13E-053.84E-053.39E-053.07E-05 9.88E-051.00E-041.00E-041.00E-049 .85E-059.75E-059.51E-059.29E-058 .44E-057.80E-056.82E-056.22E-05 2.17E-042.20E-042.23E-042.24E-042 .24E-042.22E-042.15E-042.07E-041 .91E-041.80E-041.58E-041.41E-04 3.33E-063.61E-064.05E-064.38E-064 .58E-064.72E-064.88E-064.96E-064 .93E-064.85E-064.57E-064.31E-06 4.33E-055.03E-054.68E-054.92E-055 .19E-055.09E-054.55E-054.77E-054 .42E-053.79E-053.59E-053.00E-05 7.21E-056.96E-057.06E-056.94E-056 .85E-057.02E-056.80E-056.71E-055 .84E-055.39E-054.82E-054.34E-05 1.05E-041.06E-041.09E-041.10E-041 .09E-041.08E-041.04E-041.00E-049 .26E-058.54E-057.57E-056.80E-05 1.01E-041.03E-041.05E-041.05E-041 .04E-041.03E-041.00E-049.68E-058 .94E-058.23E-057.36E-056.73E-05 6.00E-065.97E-066.64E-066.73E-067 .22E-067.79E-067.49E-066.96E-067 .13E-066.98E-065.29E-065.33E-06 1.04E-041.07E-041.07E-041.07E-041 .07E-041.05E-041.03E-049.89E-059 .08E-058.23E-057.28E-056.73E-05 9.84E-061.11E-051.22E-051.28E-051 .19E-051.13E-051.21E-051.00E-051 .16E-051.01E-057.92E-067.29E-06 5.95E-066.51E-067.22E-067.65E-067 .72E-068.02E-067.81E-067.84E-067 .42E-067.67E-066.77E-066.14E-06 3.01E-043.03E-043.11E-043.10E-043 .07E-043.03E-042.92E-042.82E-042 .60E-042.40E-042.10E-041.85E-04 2.97E-043.03E-043.10E-043.11E-043 .09E-043.05E-042.95E-042.86E-042 .60E-042.42E-042.12E-041.89E-04 1.40E-041.43E-041.46E-041.46E-041 .45E-041.43E-041.39E-041.33E-041 .23E-041.14E-041.00E-049.03E-05 1.37E-041.38E-041.40E-041.40E-041 .38E-041.38E-041.34E-041.28E-041 .19E-041.11E-049.83E-058.95E-05 5.05E-055.07E-055.12E-055.11E-055 .09E-054.99E-054.86E-054.74E-054 .44E-054.15E-053.68E-053.45E-05 1.57E-041.60E-041.63E-041.63E-041 .62E-041.59E-041.55E-041.50E-041 .37E-041.27E-041.12E-049.99E-05 5.41E-055.38E-055.44E-055.45E-055 .35E-055.26E-055.12E-055.01E-054 .64E-054.28E-053.85E-053.45E-05 1.45E-041.47E-041.50E-041.51E-041 .51E-041.48E-041.44E-041.39E-041 .28E-041.17E-041.03E-049.46E-05 5.50E-055.39E-055.46E-055.38E-055 .35E-055.36E-055.38E-055.14E-054 .73E-054.39E-053.84E-053.58E-05 1.32E-041.34E-041.34E-041.35E-041 .33E-041.32E-041.26E-041.21E-041 .09E-041.03E-049.22E-058.80E-05 2.00E-052.02E-051.97E-052.10E-052 .13E-052.09E-052.06E-052.15E-051 .99E-051.78E-051.56E-051.44E-05 5.97E-068.50E-069.27E-061.05E-059 .62E-061.04E-051.11E-051.09E-055 .63E-067.53E-068.23E-064.93E-06 4.94E-045.12E-045.32E-045.36E-045 .33E-045.25E-045.04E-044.81E-044 .22E-043.73E-042.99E-042.48E-04 7.42E-057.47E-057.54E-057.52E-057 .47E-057.37E-057.17E-056.89E-056 .42E-055.91E-055.29E-054.84E-05 1.29E-041.31E-041.33E-041.33E-041 .33E-041.31E-041.28E-041.23E-041 .13E-041.05E-049.35E-058.40E-05 8.90E-068.87E-068.37E-061.07E-051 .23E-051.21E-051.13E-051.16E-051 .06E-051.10E-058.48E-067.64E-06 6.91E-067.51E-068.65E-069.04E-069 .31E-061.00E-051.01E-051.01E-058 .30E-069.30E-067.38E-067.06E-06 1.60E-051.62E-051.55E-051.61E-051 .66E-051.68E-051.62E-051.50E-051 .46E-051.58E-051.32E-051.18E-05 3.37E-052.87E-053.14E-052.98E-053 .21E-053.07E-053.34E-053.10E-053 .10E-052.53E-052.24E-052.18E-05 7.47E-057.45E-057.59E-057.50E-057 .48E-057.34E-057.09E-056.86E-056 .44E-055.93E-055.26E-054.80E-05 1.21E-059.98E-061.12E-051.08E-051 .03E-051.08E-051.14E-051.20E-051 .21E-051.09E-051.11E-059.52E-06 4.39E-065.84E-065.22E-066.31E-066 .57E-067.10E-066.89E-067.54E-069 .60E-066.25E-065.52E-064.60E-06 2.61E-052.67E-052.60E-052.64E-052 .75E-052.69E-052.60E-052.55E-052 .39E-052.18E-051.99E-051.84E-05 2.70E-052.71E-052.75E-052.76E-052 .73E-052.71E-052.64E-052.60E-052 .42E-052.25E-052.02E-051.90E-05 1.15E-051.22E-051.25E-051.30E-051 .31E-051.34E-051.30E-051.32E-051 .29E-051.20E-051.10E-051.03E-05 6.96E-056.99E-057.10E-057.10E-057 .07E-056.96E-056.76E-056.55E-056 .03E-055.58E-054.95E-054.51E-05 6.88E-056.90E-056.96E-056.97E-056 .90E-056.83E-056.66E-056.44E-055 .95E-055.57E-054.92E-054.51E-05 2.38E-052.46E-052.59E-052.63E-052 .63E-052.60E-052.51E-052.42E-052 .20E-052.03E-051.81E-051.67E-05 6.30E-056.40E-056.51E-056.60E-056 .62E-056.55E-056.39E-056.17E-055 .63E-055.18E-054.63E-054.37E-05 7.40E-057.39E-057.57E-057.58E-057 .56E-057.42E-057.24E-056.99E-056 .47E-055.98E-055.26E-054.83E-05 1.49E-041.51E-041.54E-041.52E-041 .50E-041.48E-041.45E-041.39E-041 .28E-041.19E-041.04E-049.32E-05 1.40E-041.41E-041.43E-041.42E-041 .41E-041.39E-041.35E-041.30E-041 .19E-041.10E-049.72E-058.84E-05 4.92E-054.95E-054.98E-055.00E-054 .97E-054.90E-054.83E-054.69E-054 .27E-054.06E-053.55E-053.24E-05 2.17E-052.19E-052.24E-052.37E-052 .24E-052.16E-052.26E-052.23E-052 .04E-051.85E-051.73E-051.64E-05 1.63E-051.68E-051.76E-051.84E-051 .80E-051.85E-051.82E-051.80E-051 .64E-051.59E-051.38E-051.30E-05 1.49E-051.15E-051.33E-051.58E-051 .54E-051.63E-051.52E-051.70E-051 .35E-051.18E-051.38E-051.34E-05 3.89E-053.86E-054.01E-054.02E-054 .08E-053.96E-054.08E-053.84E-053 .55E-052.98E-052.76E-052.51E-05 1.66E-051.69E-051.79E-051.81E-051 .81E-051.84E-051.82E-051.78E-051 .61E-051.49E-051.37E-051.28E-05 1.59E-051.61E-051.69E-051.76E-051 .75E-051.74E-051.74E-051.71E-051 .62E-051.52E-051.36E-051.27E-05 2.07E-052.12E-052.14E-052.15E-052 .11E-052.10E-052.07E-052.03E-051 .96E-051.80E-051.65E-051.54E-05 7.08E-027.18E-027.15E-026.87E-026 .58E-026.37E-026.04E-025.80E-025 .35E-025.06E-024.73E-024.55E-02 4.76E-054.82E-054.91E-054.92E-054 .93E-054.84E-054.78E-054.64E-054 .28E-053.98E-053.53E-053.23E-05 4.71E-054.74E-054.84E-054.85E-054 .81E-054.79E-054.68E-054.52E-054 .19E-053.93E-053.51E-053.20E-05 1.67E-051.76E-051.76E-051.75E-051 .82E-051.82E-051.76E-051.73E-051 .68E-051.56E-051.37E-051.29E-05 1.84E-051.90E-052.02E-051.93E-051 .96E-051.97E-052.01E-052.00E-051 .91E-051.67E-051.46E-051.44E-05 5.44E-067.26E-061.11E-051.49E-051 .86E-052.21E-052.89E-053.51E-054 .86E-056.05E-058.03E-059.75E-05 3.79E-053.70E-053.64E-053.59E-053 .52E-053.46E-053.35E-053.23E-052 .97E-052.74E-052.38E-052.11E-05 3.64E-053.49E-053.47E-053.41E-053 .35E-053.29E-053.19E-053.07E-052 .83E-052.61E-052.27E-052.01E-05 Energy (MeV) 54

PAGE 55

Table 3-2. Source organ residence times for 99mTc-DMSA in a newborn. Source organ Residence time (h) Bladder contents 0.22 Heart contents 0.10 Kidneys 2.88 Liver 0.40 Lungs 0.15 Spleen 0.10 Rest of body 5.25 Table 3-3. Internal dosimetry results and tissu e weighting factors for the renal function case study. Target Organ equivalent dose (mSv / MBq) wTWeighted dose (mSv/MBq) Ovaries 6.93E-02 0.251.73E-02 Breast 2.04E-02 0.153.06E-03 Active Marrow 5.11E-02 0.126.13E-03 Lung 4.62E-02 0.125.55E-03 Thyroid 2.45E-02 0.037.34E-04 Endosteum 4.66E-02 0.031.40E-03 Remainder 5.75E-02 0.301.72E-02 55

PAGE 56

Figure 3-1. Dose response f unctions for active bone marrow and bone endosteum targets and kerma response functions for spongiosa and active bone marrow targets for the mandible. 56

PAGE 57

A B Figure 3-2. Skeletal dose respons e functions for all bone sites. A) Active bone marrow target. B) Bone endosteum target. 57

PAGE 58

Figure 3-3. Specific absorbed fractions to select ed target tissues from the liver source in the female UF newborn hybrid phantom. 58

PAGE 59

CHAPTER 4 DISCUSSION ORNL Dose Response Functions During the development of the ORNL series of phantoms, skeletal DRFs were calculated and implemented, and these DRFs were calcula ted based on Equation 2-1. There were two distinct differences between the UF and ORNL methods of creating skeletal DRFs. The first difference was that ORNL used chord-length di stributions of trabecul ae and marrow cavities to obtain electron AFs ( 9 ) while UF actually performed deta iled 3D radiation transport on the microstructure using EGSnrc. The second diffe rence was that the UF skeletal DRFs were calculated based on data specific to the newborn phantom while the ORNL data was based on a 44 year old male and applied to all phantoms. One large difference between newborn and adult microstructure is that the ne wborn has almost no inactive marrow. This difference cannot be ignored, so age-dependent DRFs are needed. Immediately it could be seen that the UF DRFs utilized more detailed physics modeling and were more specific to the phantom of interest. Three bone sites from the ORNL DRF data were selected for comparison and were chosen to be the cervical vertebra, lumbar vertebra, and ri bs. The target was chosen to be AM. The UF and ORNL DRFs for those bone sites and AM ta rget along with the per cent difference between them can be seen in Table 4-1. The average ab solute percent difference was found to be ~11%. At intermediate incident phot on energies, the DRFs were f ound to be relatively close in agreement, but they tended to diverge at higher energies and at those energies where the DRF ceased to decline and began to increase. A graphi cal depiction of this comparison can be seen in Figure 4-1. The difference between these DRFs can be attributed to those reasons previously discussed: superior physics and anatomical spec ificity for the UF calculation of new skeletal DRFs. 59

PAGE 60

ORNL Newborn Specific Absorbed Fractions The SAF data set reported by OR NL includes combinations of 56 source organs, 35 target organs, and 12 photon energies ( 27). So, it was evident at first sight that the SAF data produced for the UF newborn hybrid phantom was more comprehensive than the ORNL data with 61 source organs for the female, 63 source organs for the male, 60 target organs for the female, 62 target organs for the male, and 21 photon energies for both. Another advantage of the UF data was that it considered gender dependency more than ORNL. There are slight structure differences between the male and female phantom s which have the ability to perturb the photon fluence for certain source orga n and photon energy combinations. The ORNL newborn stylized phantom is a hermaphrodite and so does not take into account the difference in photon interactions between male a nd female, however slight. For this comparison, a representative sour ce organ was chosen to compare the SAFs calculated using the UF newbor n hybrid phantom to those obtained using the ORNL newborn stylized phantom. The source organ was chosen to be the liver, as before, for the female phantom. Several target tissues were arbitrarily selected for comparison. SAF data for the ORNL newborn stylized phantom we re taken from ORNL/TM-8381/V6 ( 27). The percent difference between the UF newborn female hybr id phantom and the ORNL newborn stylized phantom SAFs for the liver source can be seen in Table 4-2. The percent difference was calculated with respect to the ORNL phantom, so a positive percent difference means that the UF phantom showed a greater SAF for that partic ular source-target-energy combination. Several values were removed from Table 4-2 fo r one of two reasons. The first scenario in which data was removed from this table was if both the UF and ORNL SAFs were found to be effectively zero. Mathematically, even though both SAFs were found to be the same, this similarity produced no meaningful information. It simply meant that the emitted photons were 60

PAGE 61

not of great enough energy to reach the target organ of interest. The second scenario in which data was removed from the table wa s if both SAFs were reported to be greater than zero, but the ORNL SAF was so close to zero th at a percent difference created a very large percent difference. For example, was found to be 1.42 x 10-8 g-1 for the UF phantom and 2.51 x 10-12 g-1 for the ORNL phantom, produci ng a percent difference of 566354%. Obviously, this was not a meaningful result. Th e ORNL SAF was so close to zero that it could be considered effectively zero. MeV Liver Spleen01.0, It was found from this comparison that while the UF SAFs were generally of the same order of magnitude as the ORNL SAFs, there was still a significant change in many of the SAFs. The overall average absolute difference between the SAFs calculated for the UF and ORNL phantoms was found to be ~74%. Once it was proven that there was a fairly significant difference between the SAFs based on the stylized and hybrid phantoms, it was necessar y to evaluate whether this new set of SAFs was an improvement upon the old SAFs. In view of the previous discussions on the anatomical accuracy of the new UF hybrid phantoms, it was surmised that the SAFs calculated based on these phantoms were an improvement upon those based on the ORNL stylized phantoms. Not only are the SAFs more accurate because the anatomy in the hybrid phantoms more closely resembles real human anatomy, but the phant oms can easily be extended to different body morphometries for internal dose asse ssment of non-50% ile individuals. Renal Function Case Study The results of the renal func tion dosimetry case study were compared to the dosimetry from a previous study which used th e ORNL newborn stylized phantom (20). The comparison can be seen in Table 4-3. While th e electron dosimetry was admittedly rough, 99mTc is 61

PAGE 62

62 principally a single photon emitter, so the electro n component of the total dose is a relatively small fraction of the whole. Therefore, it was not completely inappropriate to compare the results of the comprehensive photon dosimetry and rough electron dosimetry of the UF newborn female hybrid phantom with the ORNL newborn st ylized phantom. It was found that there were fairly significant differences in the estimate dose to individual organs but not a large difference in the whole-body effective dose. Overall, this analysis showed that it is relatively straight forward to calculate the individual organ equivalent doses and whol e-body effective dose with the SAF data generated from this study. This data could be a pplied to any radionuclide and th erefore any nuclear medicine imaging, or even therapy, procedure. Incorporat ed into a software package, dose estimates could be provided very quickly and possi bly recorded for every nuclear medicine imaging procedure. With vast records of dose estimates, patients could be tracked throughout their lives, and updated radiation risk estimates could be provided. Another application of these SAFs could be imaging optim ization. With quick estimates of whole-body effective dose, imag e quality could be indexed agai nst administered activity and effective dose. The analysis of these results could yield imaging prot ocols which maximize the image quality and minimize the absorbed dose.

PAGE 63

Table 4-1. Percent difference between the UF newborn female hybrid phantom and the ORNL adult stylized phantom skeletal dose response functions for selected bone sites ( 9 ). Photon energy (MeV)Cervical vertebraLumbar vertebraRibsCervical vertebraLumbar vertebraRibsCervical vertebraLumbar vertebraRibs 0.01 6.32E-16 6.32E-166.33E-166.16E-166.14E-166.12E-16 3% 3% 3% 0.015 2.76E-16 2.75E-162.76E-162.62E-162.61E-162.59E-16 5% 6% 7% 0.02 1.55E-16 1.55E-161.55E-161.45E-161.43E-161.41E-16 7% 8% 10% 0.03 7.44E-17 7.42E-177.45E-176.60E-176.44E-176.29E-17 13% 15% 19% 0.04 4.98E-17 4.95E-174.99E-174.27E-174.11E-173.99E-17 17% 21% 25% 0.05 4.07E-17 4.05E-174.08E-173.45E-173.31E-173.20E-17 18% 22% 27% 0.06 3.77E-17 3.76E-173.79E-173.26E-173.11E-173.01E-17 16% 21% 26% 0.08 3.97E-17 3.96E-173.97E-173.58E-173.45E-173.36E-17 11% 15% 18% 0.1 4.61E-17 4.61E-174.61E-174.33E-174.22E-174.14E-17 6% 9% 11% 0.15 6.90E-17 6.91E-176.88E-176.83E-176.74E-176.68E-17 1% 3% 3% 0.2 9.61E-17 9.63E-179.56E-179.63E-179.57E-179.52E-17 0% 1% 0% 0.3 1.48E-16 1.48E-161.49E-161.54E-161.54E-161.53E-16 -4% -4% -3% 0.4 2.01E-16 2.02E-162.03E-162.12E-162.10E-162.10E-16 -5% -4% -3% 0.5 2.53E-16 2.54E-162.56E-162.67E-162.66E-162.65E-16 -5% -5% -4% 0.6 3.02E-16 3.03E-163.05E-163.20E-163.19E-163.17E-16 -6% -5% -4% 0.8 3.94E-16 3.95E-163.97E-164.17E-164.15E-164.14E-16 -6% -5% -4% 1 4.76E-16 4.78E-164.81E-165.06E-165.03E-165.01E-16 -6% -5% -4% 1.5 6.52E-16 6.54E-166.59E-166.95E-166.91E-166.89E-16 -6% -5% -4% 2 7.97E-16 7.99E-168.05E-168.56E-168.50E-168.47E-16 -7% -6% -5% 3 1.02E-15 1.03E-151.03E-151.13E-151.12E-151.11E-15 -9% -8% -7% 4 1.20E-15 1.20E-151.21E-151.37E-151.37E-151.35E-15 -13% -12% -10% 5 1.34E-15 1.34E-151.35E-151.60E-151.59E-151.57E-15 -16% -15% -14% 6 1.46E-15 1.47E-151.47E-151.82E-151.80E-151.78E-15 -20% -19% -17% 8 1.66E-15 1.66E-151.67E-152.27E-152.23E-152.20E-15 -27% -26% -24% 10 1.82E-15 1.82E-151.83E-152.71E-152.66E-152.62E-15 -33% -31% -30% UF newborn hybrid phantom ORNL adult male Difference 63

PAGE 64

64 Table 4-2. Difference between the UF new born female hybrid phantom and the ORNL new born stylized phantom SAFs for selected target organs for the liver source. Source = Liver Target 0.010.0150.020.030.050.10.20.511.524 Adrenals 117%36%36%32%27%25%23%27%29%26%26%30% Urinary bladder wall ---53%-64%-36%-38%-30%-29%-27%-27%-28%-28%-32% Endosteum -90%-85%-83%-79%-70%-39%0%8%3%4%4%-3% Brain ----657%89%109%58%74%60%48%54%58%36% Breasts ---33%-5%0%0%4%9%3%3%1%-8%-8% Stomach wall 703%133%70%44%38%35%33%32%28%28%30%38% Small intestine wall 45%37%10%-12%-17%-14%-12%-12%-18%-16%-15%-13% Kidneys 311%103%49%22%9%5%3%3%6%9%10%3% Liver -5%-5%-5%-4%-5%-6%-6%-8%-9%-14%-18%-32% Ovaries ---64%-48%-41%-28%-28%-29%-18%-12%-11%-25%-19% Pancreas ---95%-83%-65%-52%-51%-53%-54%-52%-52%-53%-53% Active marrow -31%6%31%63%85%94%91%75%64%63%62%54% Skin -94%-44%-18%4%16%13%4%2%-1%-5%-6%-6% Spleen --1388%290%96%58%50%50%46%48%53%52%40% Thymus --2256%446%171%118%100%83%72%85%87%90%67% Thyroid ----1007%163%94%75%74%73%70%61%52%61% Gall bladder wall 2%13%7%7%7%6%8%3%2%3%2%-2% Heart wall 677%169%102%73%54%49%44%45%43%44%45%46% Uterus ---93%-75%-63%-51%-46%-44%-47%-43%-43%-46%-40% Photon energy (MeV)

PAGE 65

Table 4-3. Dosimetry comparis on between a previous dose estimation for the renal function case study and the dose estimation using the UF newborn hybrid phantom (20). Previous studyUF hybridDifference Kidneys 2.0001.518 -24% Ovaries 0.0370.069 87% Endosteum 0.0520.036 -30% Active marrow 0.0290.038 30% Urinary bladder wall 0.0520.067 30% Whole-body effective dose 0.1600.163 2% Normalized dose (mSv / MBq) Target 65

PAGE 66

Figure 4-1. UF newborn hybrid phantom and ORNL adult male stylized phantom dose response functions for the cervical vertebra with AM as the target ( 9 ). 66

PAGE 67

CHAPTER 5 CONCLUSION A recent study showed a considerable variability in the administered activity to pediatric patients undergoing nuclear medicine imaging pro cedures with a maximum variation of 8.5 and an average variation of 3 (28). This means that if a particular pediatric patient was scanned at one hospital, there was a chance that the child would receive up to 8.5 times the administered activity for the same procedure at a different in stitution. Obviously, in this scenario, one institution considers their administered activity sufficient to produce a quality image while another institution overdoses the child to potentially obtain the same result. This example shows that there is a great need for accurate dosimetry in nuclear medicine imaging. How much activity is enough to produce the optimal quality image for this child? This question has not yet been answered, but to answ er that question, high quality dosimetry methods are needed to analyze the dosing protocols. To date, the internal dosimetry parameters, SAFs, were taken from the ORNL series of stylized phantoms. As discussed previously, these phantoms are simply not anatomically accurate. They do not faithfully represent human anatomy in shape and sometimes position. In addition, the simple skeletal m odels do not take into account detailed radi ation transport in the sk eletal microstructure. The UF hybrid series of phantoms possesses anatomical accuracy as well as an updated skeletal microstructure. In th is study, the UF newborn hybrid pha ntoms were used to calculate a new set of SAFs for a wide range of source-targ et-energy combinations. These new SAFs were shown to be applicable for not only the renal function case study but for any nuclear medicine imaging procedure. The new SAFs were shown to differ significantly from the SAFs calculated by ORNL for their stylized newborn phantom. The comparison between these SAFs demonstrated the need to utilize the UF hybrid phantom series for internal dosimetry. 67

PAGE 68

68 The application of this new set of SAFs to nuclear medicine imaging dosimetry is boundless provided accurate biokinetics and radionuc lide information are available. The results of this study will be able to be used in the future by anyone when it is imbedded in a software program. Along with the newborn phantom, the re st of the UF hybrid phantom series will be included and will provide a complete internal dosimetry model that may be adopted by international governing bodies. So, this study ha s the capability of grea tly contributing to the ever improving field of computational radiation dosimetry.

PAGE 69

APPENDIX A SAMPLE FILES Sample Lattice File (Excerpt) 1000 0 -200 lat=1 u=999 imp:p=1 imp:e=1 fill=0:345 0:211 0:715 57 15588r 43 57 306r 43 57 34r 43 4r 57 302r 43 4r 57 31r 43 6r 57 300r 43 6r 57 29r 43 7r 57 300r 43 7r 57 28r 43 8r 57 298r 43 8r 57 28r 43 8r 57 298r 43 8r 57 28r 43 9r 57 296r 43 9r 57 28r 43 9r 57 296r 43 9r 57 29r Sample Source Files (Excerpts) Uniform Sampling Probability (Liver Source) si5 l (25<1000[ 109 132 306]<1001) (25<1000[ 109 133 306]<1001) (25<1000[ 109 134 306]<1001) (25<1000[ 108 126 307]<1001) (25<1000[ 109 126 307]<1001) (25<1000[ 110 126 307]<1001) (25<1000[ 108 127 307]<1001) (25<1000[ 109 127 307]<1001) (25<1000[ 110 127 307]<1001) (25<1000[ 107 128 307]<1001) (25<1000[ 150 112 444]<1001) (25<1000[ 145 113 444]<1001) (25<1000[ 146 113 444]<1001) (25<1000[ 147 113 444]<1001) (25<1000[ 148 113 444]<1001) (25<1000[ 149 113 444]<1001) (25<1000[ 146 114 444]<1001) (25<1000[ 147 114 444]<1001) (25<1000[ 148 114 444]<1001) sp5 1 427350r Non-Uniform Sampling Probability (AM Source) si5 s d201 d202 d203 d204 d205 d206 d207 d208 d209 d210 d211 d212 d213 d214 d215 d216 d217 d218 d219 d220 d221 d222 d223 d224 d225 d226 d227 d228 d229 d230 d231 d232 d233 d234 sp5 0.2412 0.0433 0.0373 0.0516 0.0470 0.0051 0.1628 0.0323 0.0122 0.0631 0.0188 0.0212 0.0045 0.0045 0.0166 0.0036 0.0017 0.0065 0.0086 0.0020 0.0044 0.0242 0.0346 0.0103 0.0164 0.0286 0.0013 0.0246 0.0094 0.0151 0.0033 0.0015 0.0050 0.0375 si201 l (201<1000[ 173 53 569]<1001) (201<1000[ 174 53 569]<1001) (201<1000[ 171 54 569]<1001) (201<1000[ 172 54 569]<1001) (201<1000[ 173 54 569]<1001) (201<1000[ 174 54 569]<1001) (201<1000[ 156 156 709]<1001) (201<1000[ 156 157 709]<1001) (201<1000[ 157 158 709]<1001) sp201 1 166946r si234 l (234<1000[ 56 110 255]<1001) (234<1000[ 57 110 255]<1001) (234<1000[ 289 110 255]<1001) (234<1000[ 290 110 255]<1001) (234<1000[ 56 111 255]<1001) (234<1000[ 57 111 255]<1001) 69

PAGE 70

(234<1000[ 56 104 322]<1001) (234<1000[ 290 104 322]<1001) (234<1000[ 291 104 322]<1001) (234<1000[ 292 104 322]<1001) sp234 1 7437r Sample MCNPX Input File (Excerpt) Female Newborn Phantom 4 MeV Photon Energy Liver Source c --------------------------------------------------------c --------------------------------------------------------c --------------------------------------------------------c c UFH Newborn Female c Mike Wayson c Contributions from Choonsik Lee c The University of Florida c Complete Dosimetry Characterization (SAFs) c ALRADS Research Group c c --------------------------------------------------------c --------------------------------------------------------c --------------------------------------------------------c read file=nbfpe.lat noecho 1001 0 -100 fill=999 imp:p=1 imp:e=1 $ Surrounding Box c c --------------------------------------------------------c --------------------------------------------------------c c Body composition and density c c --------------------------------------------------------c --------------------------------------------------------c 1 1 -1.02 -70 u=1 imp:p=1 imp:e=1 vol=2085.280 $ Residual Soft Tissue 2 1 -1.02 -70 u=2 imp:p=1 imp:e=1 vol=2.899 $ Adrenal (L) 3 1 -1.02 -70 u=3 imp:p=1 imp:e=1 vol=2.880 $ Adrenal (R) 4 1 -1.02 -70 u=4 imp:p=1 imp:e=1 vol=307.483 $ Brain 5 1 -1.02 -70 u=5 imp:p=1 imp:e=1 vol=0.043 $ Breast 6 1 -1.02 -70 u=6 imp:p=1 imp:e=1 vol=0.355 $ Bronchi 7 1 -1.02 -70 u=7 imp:p=1 imp:e=1 vol=6.710 $ Right Colon W 8 1 -1.02 -70 u=8 imp:p=1 imp:e=1 vol=15.123 $ Right Colon C 9 1 -1.02 -70 u=9 imp:p=1 imp:e=1 vol=0.963 $ Ears 10 1 -1.02 -70 u=10 imp:p=1 imp:e=1 vol=1.900 $ Esophagus 11 1 -1.02 -70 u=11 imp:p=1 imp:e=1 vol=0.234 $ External nose 12 1 -1.02 -70 u=12 imp:p=1 imp:e=1 vol=5.752 $ Eye balls 13 1 -1.02 -70 u=13 imp:p=1 imp:e=1 vol=0.481 $ Gall Bladder W 14 1 -1.02 -70 u=14 imp:p=1 imp:e=1 vol=2.720 $ Gall Bladder C 15 1 -1.02 -70 u=15 imp:p=1 imp:e=1 vol=19.134 $ Heart W 16 1 -1.02 -70 u=16 imp:p=1 imp:e=1 vol=5.647 $ Heart C 17 1 -1.02 -70 u=17 imp:p=1 imp:e=1 vol=8.908 $ Kidney-cortex (L) 18 1 -1.02 -70 u=18 imp:p=1 imp:e=1 vol=8.911 $ Kidney-cortex (R) 19 1 -1.02 -70 u=19 imp:p=1 imp:e=1 vol=3.180 $ Kidney-medulla (L) 20 1 -1.02 -70 u=20 imp:p=1 imp:e=1 vol=3.179 $ Kidney-medulla (R) 21 1 -1.02 -70 u=21 imp:p=1 imp:e=1 vol=0.637 $ Kidney-pelvis (L) 70

PAGE 71

22 1 -1.02 -70 u=22 imp:p=1 imp:e=1 vol=0.636 $ Kidney-pelvis (R) 23 1 -1.02 -70 u=23 imp:p=1 imp:e=1 vol=1.216 $ Larynx 24 1 -1.02 -70 u=24 imp:p=1 imp:e=1 vol=0.122 $ Lens 25 1 -1.02 -70 u=25 imp:p=1 imp:e=1 vol=124.545 $ Liver 26 2 -0.62 -70 u=26 imp:p=1 imp:e=1 vol=46.428 $ Lung (L) 27 2 -0.62 -70 u=27 imp:p=1 imp:e=1 vol=50.660 $ Lung (R) 28 1 -1.02 -70 u=28 imp:p=1 imp:e=1 vol=0.080 $ Nasal layer (anterior) 29 1 -1.02 -70 u=29 imp:p=1 imp:e=1 vol=0.715 $ Nasal layer (posterior) 30 1 -1.02 -70 u=30 imp:p=1 imp:e=1 vol=0.716 $ Oral cavity layer 31 1 -1.02 -70 u=31 imp:p=1 imp:e=1 vol=0.287 $ Ovaries <-32 1 -1.02 -70 u=32 imp:p=1 imp:e=1 vol=5.791 $ Pancreas c 33 1 -1.02 -70 u=33 imp:p=1 imp:e=1 vol=0.000 $ Penis <-34 1 -1.02 -70 u=34 imp:p=1 imp:e=1 vol=0.277 $ Pharynx 35 1 -1.02 -70 u=35 imp:p=1 imp:e=1 vol=0.096 $ Pituitary Gland c 36 1 -1.02 -70 u=36 imp:p=1 imp:e=1 vol=0.000 $ Prostate <-37 1 -1.02 -70 u=37 imp:p=1 imp:e=1 vol=2.917 $ Rectosigmoid W 38 1 -1.02 -70 u=38 imp:p=1 imp:e=1 vol=9.220 $ Rectosigmoid C 39 1 -1.02 -70 u=39 imp:p=1 imp:e=1 vol=3.393 $ Salivary Glands (parotid) c 40 1 -1.02 -70 u=40 imp:p=1 imp:e=1 vol=0.000 $ Scrotum <-41 1 -1.02 -70 u=41 imp:p=1 imp:e=1 vol=28.175 $ SI W 42 1 -1.02 -70 u=42 imp:p=1 imp:e=1 vol=30.330 $ SI C 43 1 -1.02 -70 u=43 imp:p=1 imp:e=1 vol=143.621 $ Skin 44 1 -1.02 -70 u=44 imp:p=1 imp:e=1 vol=6.099 $ Spinal Cord 45 1 -1.02 -70 u=45 imp:p=1 imp:e=1 vol=9.103 $ Spleen 46 1 -1.02 -70 u=46 imp:p=1 imp:e=1 vol=6.767 $ Stomach W 47 1 -1.02 -70 u=47 imp:p=1 imp:e=1 vol=24.555 $ Stomach C c 48 1 -1.02 -70 u=48 imp:p=1 imp:e=1 vol=0.000 $ Testes <-49 1 -1.02 -70 u=49 imp:p=1 imp:e=1 vol=12.122 $ Thymus 50 1 -1.02 -70 u=50 imp:p=1 imp:e=1 vol=1.227 $ Thyroid 51 1 -1.02 -70 u=51 imp:p=1 imp:e=1 vol=3.340 $ Tongue 52 1 -1.02 -70 u=52 imp:p=1 imp:e=1 vol=0.098 $ Tonsil 53 1 -1.02 -70 u=53 imp:p=1 imp:e=1 vol=0.475 $ Trachea 54 1 -1.02 -70 u=54 imp:p=1 imp:e=1 vol=3.814 $ Urinary bladder W 55 1 -1.02 -70 u=55 imp:p=1 imp:e=1 vol=9.947 $ Urinary bladder C 56 1 -1.02 -70 u=56 imp:p=1 imp:e=1 vol=3.775 $ Uterus <-57 4 -0.0012 -70 u=57 imp:p=1 imp:e=1 vol=1.540 $ Air (in body) 58 1 -1.02 -70 u=58 imp:p=1 imp:e=1 vol=6.787 $ Left Colon W 59 1 -1.02 -70 u=59 imp:p=1 imp:e=1 vol=18.398 $ Left Colon C 60 1 -1.02 -70 u=60 imp:p=1 imp:e=1 vol=1.740 $ Salivary Glands (submaxillary) 61 1 -1.02 -70 u=61 imp:p=1 imp:e=1 vol=0.676 $ Salivary Glands (sublingual) 101 5 -1.10 -70 u=101 imp:p=1 imp:e=1 vol=35.079 $ c-Cranium 102 5 -1.10 -70 u=102 imp:p=1 imp:e=1 vol=2.453 $ c-Mandible 103 5 -1.10 -70 u=103 imp:p=1 imp:e=1 vol=2.486 $ c-Scapulae 104 5 -1.10 -70 u=104 imp:p=1 imp:e=1 vol=1.215 $ c-Clavicles 105 5 -1.10 -70 u=105 imp:p=1 imp:e=1 vol=1.432 $ c-Sternum 106 5 -1.10 -70 u=106 imp:p=1 imp:e=1 vol=4.073 $ c-Ribs 107 5 -1.10 -70 u=107 imp:p=1 imp:e=1 vol=3.832 $ c-Vertebrae-C 108 5 -1.10 -70 u=108 imp:p=1 imp:e=1 vol=7.208 $ c-Vertebrae-T 109 5 -1.10 -70 u=109 imp:p=1 imp:e=1 vol=3.879 $ c-Vertebrae-L 110 5 -1.10 -70 u=110 imp:p=1 imp:e=1 vol=1.766 $ c-Sacrum 111 5 -1.10 -70 u=111 imp:p=1 imp:e=1 vol=5.351 $ c-Os Coxae 112 5 -1.10 -70 u=112 imp:p=1 imp:e=1 vol=2.451 $ c-Femora-p 113 5 -1.10 -70 u=113 imp:p=1 imp:e=1 vol=2.158 $ c-Femora-d 114 5 -1.10 -70 u=114 imp:p=1 imp:e=1 vol=1.601 $ c-Tibiae-p 115 5 -1.10 -70 u=115 imp:p=1 imp:e=1 vol=1.507 $ c-Tibiae-d 116 5 -1.10 -70 u=116 imp:p=1 imp:e=1 vol=0.636 $ c-Fibulae-p 71

PAGE 72

117 5 -1.10 -70 u=117 imp:p=1 imp:e=1 vol=0.842 $ c-Fibulae-d 118 5 -1.10 -70 u=118 imp:p=1 imp:e=1 vol=0.129 $ c-Patellae 119 5 -1.10 -70 u=119 imp:p=1 imp:e=1 vol=3.752 $ c-Feet 120 5 -1.10 -70 u=120 imp:p=1 imp:e=1 vol=1.521 $ c-Humera-p 121 5 -1.10 -70 u=121 imp:p=1 imp:e=1 vol=1.790 $ c-Humera-d 122 5 -1.10 -70 u=122 imp:p=1 imp:e=1 vol=0.595 $ c-Radii-p 123 5 -1.10 -70 u=123 imp:p=1 imp:e=1 vol=0.839 $ c-Radii-d 124 5 -1.10 -70 u=124 imp:p=1 imp:e=1 vol=0.873 $ c-Ulnae-p 125 5 -1.10 -70 u=125 imp:p=1 imp:e=1 vol=0.906 $ c-Ulnae-d 126 5 -1.10 -70 u=126 imp:p=1 imp:e=1 vol=3.803 $ c-Hands 127 5 -1.10 -70 u=127 imp:p=1 imp:e=1 vol=10.209 $ c-Cranial Cap 128 5 -1.10 -70 u=128 imp:p=1 imp:e=1 vol=10.531 $ c-Costal cartilage of ribs 129 5 -1.10 -70 u=129 imp:p=1 imp:e=1 vol=0.204 $ c-Cervical Discs 130 5 -1.10 -70 u=130 imp:p=1 imp:e=1 vol=0.690 $ c-Thoracic Discs 131 5 -1.10 -70 u=131 imp:p=1 imp:e=1 vol=0.474 $ c-Lumbar Discs 151 3 -1.65 -70 u=151 imp:p=1 imp:e=1 vol=12.848 $ Cranium 152 3 -1.65 -70 u=152 imp:p=1 imp:e=1 vol=1.017 $ Mandible 153 3 -1.65 -70 u=153 imp:p=1 imp:e=1 vol=1.458 $ Scapulae 154 3 -1.65 -70 u=154 imp:p=1 imp:e=1 vol=0.552 $ Clavicles 155 3 -1.65 -70 u=155 imp:p=1 imp:e=1 vol=0.105 $ Sternum 156 3 -1.65 -70 u=156 imp:p=1 imp:e=1 vol=3.700 $ Ribs 157 3 -1.65 -70 u=157 imp:p=1 imp:e=1 vol=2.204 $ Vertebrae-C 158 3 -1.65 -70 u=158 imp:p=1 imp:e=1 vol=5.114 $ Vertebrae-T 159 3 -1.65 -70 u=159 imp:p=1 imp:e=1 vol=1.623 $ Vertebrae-L 160 3 -1.65 -70 u=160 imp:p=1 imp:e=1 vol=0.672 $ Sacrum 161 3 -1.65 -70 u=161 imp:p=1 imp:e=1 vol=3.724 $ Os Coxae 162 3 -1.65 -70 u=162 imp:p=1 imp:e=1 vol=0.398 $ Femora-proximal 163 3 -1.65 -70 u=163 imp:p=1 imp:e=1 vol=1.911 $ Femora-upper shaft 164 3 -1.65 -70 u=164 imp:p=1 imp:e=1 vol=3.001 $ Femora-lower shaft 165 3 -1.65 -70 u=165 imp:p=1 imp:e=1 vol=0.326 $ Femora-distal 166 3 -1.65 -70 u=166 imp:p=1 imp:e=1 vol=0.325 $ Tibiae-proximal 167 3 -1.65 -70 u=167 imp:p=1 imp:e=1 vol=2.211 $ Tibiae-shaft 168 3 -1.65 -70 u=168 imp:p=1 imp:e=1 vol=0.170 $ Tibiae-distal 169 3 -1.65 -70 u=169 imp:p=1 imp:e=1 vol=0.030 $ Fibulae-proximal 170 3 -1.65 -70 u=170 imp:p=1 imp:e=1 vol=0.618 $ Fibulae-shaft 171 3 -1.65 -70 u=171 imp:p=1 imp:e=1 vol=0.047 $ Fibulae-distal 172 3 -1.65 -70 u=172 imp:p=1 imp:e=1 vol=0.033 $ Patellae 173 3 -1.65 -70 u=173 imp:p=1 imp:e=1 vol=0.738 $ Ankles and Feet 174 3 -1.65 -70 u=174 imp:p=1 imp:e=1 vol=0.251 $ Humera-proximal 175 3 -1.65 -70 u=175 imp:p=1 imp:e=1 vol=0.957 $ Humera-upper shaft 176 3 -1.65 -70 u=176 imp:p=1 imp:e=1 vol=0.916 $ Humera-lower shaft 177 3 -1.65 -70 u=177 imp:p=1 imp:e=1 vol=0.154 $ Humera-distal 178 3 -1.65 -70 u=178 imp:p=1 imp:e=1 vol=0.035 $ Radii-proximal 179 3 -1.65 -70 u=179 imp:p=1 imp:e=1 vol=0.615 $ Radii-shaft 180 3 -1.65 -70 u=180 imp:p=1 imp:e=1 vol=0.056 $ Radii-distal 181 3 -1.65 -70 u=181 imp:p=1 imp:e=1 vol=0.119 $ Ulnae-proximal 182 3 -1.65 -70 u=182 imp:p=1 imp:e=1 vol=0.790 $ Ulnae-shaft 183 3 -1.65 -70 u=183 imp:p=1 imp:e=1 vol=0.062 $ Ulnae-distal 184 3 -1.65 -70 u=184 imp:p=1 imp:e=1 vol=0.494 $ Wrists and Hands c 185 3 -1.65 -70 u=185 imp:p=1 imp:e=1 vol=0.000 $ Teeth 201 6 -1.33 -70 u=201 imp:p=1 imp:e=1 vol=48.654 $ sp-Cranium 202 6 -1.33 -70 u=202 imp:p=1 imp:e=1 vol=3.856 $ sp-Mandible 203 6 -1.33 -70 u=203 imp:p=1 imp:e=1 vol=3.007 $ sp-Scapulae 204 6 -1.33 -70 u=204 imp:p=1 imp:e=1 vol=1.135 $ sp-Clavicles 205 6 -1.33 -70 u=205 imp:p=1 imp:e=1 vol=0.455 $ sp-Sternum 206 6 -1.33 -70 u=206 imp:p=1 imp:e=1 vol=14.466 $ sp-Ribs 72

PAGE 73

207 6 -1.33 -70 u=207 imp:p=1 imp:e=1 vol=4.641 $ sp-Vertebrae-C 208 6 -1.33 -70 u=208 imp:p=1 imp:e=1 vol=6.745 $ sp-Vertebrae-T 209 6 -1.33 -70 u=209 imp:p=1 imp:e=1 vol=5.151 $ sp-Vertebrae-L 210 6 -1.33 -70 u=210 imp:p=1 imp:e=1 vol=2.055 $ sp-Sacrum 211 6 -1.33 -70 u=211 imp:p=1 imp:e=1 vol=5.815 $ sp-Os Coxae 212 6 -1.33 -70 u=212 imp:p=1 imp:e=1 vol=3.789 $ sp-Femora-p 213 6 -1.33 -70 u=213 imp:p=1 imp:e=1 vol=0.562 $ mc-Femora-ps 214 6 -1.33 -70 u=214 imp:p=1 imp:e=1 vol=0.898 $ mc-Femora-ds 215 6 -1.33 -70 u=215 imp:p=1 imp:e=1 vol=3.139 $ sp-Femora-d 216 6 -1.33 -70 u=216 imp:p=1 imp:e=1 vol=2.696 $ sp-Tibiae-p 217 6 -1.33 -70 u=217 imp:p=1 imp:e=1 vol=0.510 $ mc-Tibiae-s 218 6 -1.33 -70 u=218 imp:p=1 imp:e=1 vol=1.655 $ sp-Tibiae-d 219 6 -1.33 -70 u=219 imp:p=1 imp:e=1 vol=0.367 $ sp-Fibulae-p 220 6 -1.33 -70 u=220 imp:p=1 imp:e=1 vol=0.083 $ mc-Fibulae-s 221 6 -1.33 -70 u=221 imp:p=1 imp:e=1 vol=0.569 $ sp-Fibulae-d 222 6 -1.33 -70 u=222 imp:p=1 imp:e=1 vol=0.115 $ sp-Patellae 223 6 -1.33 -70 u=223 imp:p=1 imp:e=1 vol=3.201 $ sp-Ankle+Feet 224 6 -1.33 -70 u=224 imp:p=1 imp:e=1 vol=2.317 $ sp-Humera-p 225 6 -1.33 -70 u=225 imp:p=1 imp:e=1 vol=0.248 $ mc-Humera-ps 226 6 -1.33 -70 u=226 imp:p=1 imp:e=1 vol=0.248 $ mc-Humera-ds 227 6 -1.33 -70 u=227 imp:p=1 imp:e=1 vol=1.820 $ sp-Humera-d 228 6 -1.33 -70 u=228 imp:p=1 imp:e=1 vol=0.393 $ sp-Radii-p 229 6 -1.33 -70 u=229 imp:p=1 imp:e=1 vol=0.100 $ mc-Radii-s 230 6 -1.33 -70 u=230 imp:p=1 imp:e=1 vol=0.701 $ sp-Radii-d 231 6 -1.33 -70 u=231 imp:p=1 imp:e=1 vol=0.947 $ sp-Ulnae-p 232 6 -1.33 -70 u=232 imp:p=1 imp:e=1 vol=0.108 $ mc-Ulnae-s 233 6 -1.33 -70 u=233 imp:p=1 imp:e=1 vol=0.473 $ sp-Ulnae-d 234 6 -1.33 -70 u=234 imp:p=1 imp:e=1 vol=2.168 $ sp-Hands c c --------------------------------------------------------c Window and Outside of Window c --------------------------------------------------------c 1002 4 -0.001205 100 -1000 imp:p=1 imp:e=1 $ Out of Voxel, Inside medium 1003 0 1000 imp:p=0 imp:e=0 $ Out of ROI c c --------------------------------------------------------c --------------------------------------------------------c c Surface Card c c --------------------------------------------------------c --------------------------------------------------------c c --------------------------------------------------------c Phantom/Voxel/Outer Sphere Dimensions c Phantom Array Size = ( 0:345 0:211 0:715 ) c --------------------------------------------------------c 100 rpp 0 22.87 0 13.99 0 47.40 200 rpp 0 .0663 0 .0663 0 .0663 1000 so 200 70 so 200 c 73

PAGE 74

c --------------------------------------------------------c MODE Definition c --------------------------------------------------------c mode p e c c --------------------------------------------------------c --------------------------------------------------------c c Material Cards c c --------------------------------------------------------c --------------------------------------------------------c c -Soft tissue (rho = 1.02 g/cc) -c M1 1000 -0.105 $ Hydrogen 6000 -0.256 $ Carbon 7000 -0.027 $ Nitrogen 8000 -0.602 $ Oxygen 11000 -0.001 $ Sodium 15000 -0.002 $ Phosphorus 16000 -0.003 $ Sulfur 17000 -0.002 $ Chlorine 19000 -0.002 $ Potassium c c -Lung (rho = 0.620) -c M2 1000 -0.103 $ Hydrogen 6000 -0.105 $ Carbon 7000 -0.031 $ Nitrogen 8000 -0.749 $ Oxygen 11000 -0.002 $ Sodium 15000 -0.002 $ Phosphorus 16000 -0.003 $ Sulfur 17000 -0.003 $ Chlorine 19000 -0.002 $ Potassium c c -Cortical Bone tissue (rho = 1.65) -ICRP 89 c M3 1000 -0.07337 $ Hydrogen 6000 -0.25475 $ Carbon 7000 -0.03057 $ Nitrogen 8000 -0.47893 $ Oxygen 9000 -0.00025 $ Fluorine 11000 -0.00326 $ Sodium 12000 -0.00112 $ Magnesium 14000 -0.00002 $ Silicon 15000 -0.05095 $ Phosphorus 16000 -0.00173 $ Sulfur 17000 -0.00143 $ Chlorine 19000 -0.00153 $ Potassium 20000 -0.10190 $ Calcium 26000 -0.00008 $ Iron 30000 -0.00005 $ Zinc 37000 -0.00002 $ Rubidium 74

PAGE 75

38000 -0.00003 $ Strontium 82000 -0.00001 $ Lead c c -Air (rho = 0.001205) -c M4 6000 -0.000124 $ Carbon 7000 -0.755267 $ Nitrogen 8000 -0.231781 $ Oxygen 18000 -0.012827 $ Argon c c -Cartilage (rho = 1.10) -Deanna et al. c M5 1000 -0.0960 $ Hydrogen 6000 -0.0990 $ Carbon 7000 -0.0220 $ Nitrogen 8000 -0.7440 $ Oxygen 11000 -0.0050 $ Sodium 15000 -0.0220 $ Phosphorus 16000 -0.0090 $ Sulfur 17000 -0.0030 $ Chlorine c c -Spongiosa (rho = 1.33) -Deanna et al. c M6 1000 -0.0662 $ Hydrogen 6000 -0.2357 $ Carbon 7000 -0.0407 $ Nitrogen 8000 -0.5003 $ Oxygen 11000 -0.0005 $ Sodium 12000 -0.0024 $ Magnesium 15000 -0.0498 $ Phosphorus 16000 -0.0027 $ Sulfur 17000 -0.0002 $ Chlorine 19000 -0.0003 $ Potassium 20000 -0.1009 $ Calcium 26000 -0.0003 $ Iron c c --------------------------------------------------------c --------------------------------------------------------c c Tally Specification c c --------------------------------------------------------c --------------------------------------------------------c c --------------------------------------------------------c General Organ Tally (KERMA) c --------------------------------------------------------c *f18:p,e 1 $ Residual Soft Tissue *f28:p,e 2 $ Adrenal (L) *f38:p,e 3 $ Adrenal (R) *f48:p,e 4 $ Brain *f58:p,e 5 $ Breast *f68:p,e 6 $ Bronchi *f78:p,e 7 $ Right Colon W *f88:p,e 8 $ Right Colon C 75

PAGE 76

*f98:p,e 9 $ Ears *f108:p,e 10 $ Esophagus *f118:p,e 11 $ External nose *f128:p,e 12 $ Eye balls *f138:p,e 13 $ Gall Bladder W *f148:p,e 14 $ Gall Bladder C *f158:p,e 15 $ Heart W *f168:p,e 16 $ Heart C *f178:p,e 17 $ Kidney-cortex (L) *f188:p,e 18 $ Kidney-cortex (R) *f198:p,e 19 $ Kidney-medulla (L) *f208:p,e 20 $ Kidney-medulla (R) *f218:p,e 21 $ Kidney-pelvis (L) *f228:p,e 22 $ Kidney-pelvis (R) *f238:p,e 23 $ Larynx *f248:p,e 24 $ Lens *f258:p,e 25 $ Liver *f268:p,e 26 $ Lung (L) *f278:p,e 27 $ Lung (R) *f288:p,e 28 $ Nasal layer (anterior) *f298:p,e 29 $ Nasal layer (posterior) *f308:p,e 30 $ Oral cavity layer *f318:p,e 31 $ Ovaries <-*f328:p,e 32 $ Pancreas c *f338:p,e 33 $ Penis <-*f348:p,e 34 $ Pharynx *f358:p,e 35 $ Pituitary Gland c *f368:p,e 36 $ Prostate <-*f378:p,e 37 $ Rectosigmoid W *f388:p,e 38 $ Rectosigmoid C *f398:p,e 39 $ Salivary Glands (parotid) c *f408:p,e 40 $ Scrotum <-*f418:p,e 41 $ SI W *f428:p,e 42 $ SI C *f438:p,e 43 $ Skin *f448:p,e 44 $ Spinal Cord *f458:p,e 45 $ Spleen *f468:p,e 46 $ Stomach W *f478:p,e 47 $ Stomach C c *f488:p,e 48 $ Testes <-*f498:p,e 49 $ Thymus *f508:p,e 50 $ Thyroid *f518:p,e 51 $ Tongue *f528:p,e 52 $ Tonsil *f538:p,e 53 $ Trachea *f548:p,e 54 $ Urinary bladder W *f558:p,e 55 $ Urinary bladder C *f568:p,e 56 $ Uterus <-*f578:p,e 57 $ Air (in body) *f588:p,e 58 $ Left Colon W *f598:p,e 59 $ Left Colon C *f608:p,e 60 $ Salivary Glands (submaxillary) *f618:p,e 61 $ Salivary Glands (sublingual) c c --------------------------------------------------------c Cartilage Tally (KERMA) 76

PAGE 77

c --------------------------------------------------------c *f1018:p,e (101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131) c c --------------------------------------------------------c Spongiosa Tally (Fluence) c --------------------------------------------------------c f2014:p 201 $ sp-Cranium E2014 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2024:p 202 $ sp-Mandible E2024 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 77

PAGE 78

0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2034:p 203 $ sp-Scapulae E2034 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2044:p 204 $ sp-Clavicles E2044 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 78

PAGE 79

0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2054:p 205 $ sp-Sternum E2054 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2064:p 206 $ sp-Ribs E2064 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 79

PAGE 80

0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2074:p 207 $ sp-Vertebrae-C E2074 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2084:p 208 $ sp-Vertebrae-T E2084 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 80

PAGE 81

0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2094:p 209 $ sp-Vertebrae-L E2094 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2104:p 210 $ sp-Sacrum E2104 0.001 0.003 0.005 0.010 0.015 0.020 0.030 81

PAGE 82

0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2114:p 211 $ sp-Os Coxae E2114 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2124:p 212 $ sp-Femora-p E2124 0.001 0.003 0.005 0.010 0.015 82

PAGE 83

0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2134:p 213 $ mc-Femora-ps E2134 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2144:p 214 $ mc-Femora-ds E2144 0.001 0.003 0.005 83

PAGE 84

0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2154:p 215 $ sp-Femora-d E2154 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2164:p 216 $ sp-Tibiae-p E2164 0.001 84

PAGE 85

0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2174:p 217 $ mc-Tibiae-s E2174 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 85

PAGE 86

f2184:p 218 $ sp-Tibiae-d E2184 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2194:p 219 $ sp-Fibulae-p E2194 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 86

PAGE 87

8.0 10.0 f2204:p 220 $ mc-Fibulae-s E2204 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2214:p 221 $ sp-Fibulae-d E2214 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 87

PAGE 88

5.0 6.0 8.0 10.0 f2224:p 222 $ sp-Patellae E2224 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2234:p 223 $ sp-Ankle+Feet E2234 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 88

PAGE 89

3.0 4.0 5.0 6.0 8.0 10.0 f2244:p 224 $ sp-Humera-p E2244 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2254:p 225 $ mc-Humera-ps E2254 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 89

PAGE 90

1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2264:p 226 $ mc-Humera-ds E2264 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2274:p 227 $ sp-Humera-d E2274 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 90

PAGE 91

0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2284:p 228 $ sp-Radii-p E2284 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2294:p 229 $ mc-Radii-s E2294 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 91

PAGE 92

0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2304:p 230 $ sp-Radii-d E2304 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2314:p 231 $ sp-Ulnae-p E2314 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 92

PAGE 93

0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2324:p 232 $ mc-Ulnae-s E2324 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2334:p 233 $ sp-Ulnae-d E2334 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 93

PAGE 94

0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 f2344:p 234 $ sp-Hands E2344 0.001 0.003 0.005 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.10 0.15 0.20 0.30 0.40 0.50 0.60 0.80 1.0 1.5 2.0 3.0 4.0 5.0 6.0 8.0 10.0 c c --------------------------------------------------------c --------------------------------------------------------c c Source Definition c c --------------------------------------------------------c --------------------------------------------------------c sdef par=p erg=4.0000 cel=d5 x=d1 y=d2 z=d3 read file=liver.src noecho 94

PAGE 95

95 # si1 sp1 si2 sp2 si3 sp3 0 0 0 0 0 0 .0663 1 .0663 1 .0663 1 nps 1e7

PAGE 96

APPENDIX B ORIGINAL CODES Skeletal Dose Response Function Code tic drf_am=xlsread( 'drf.xls' 'am', 'b4:u31' ); drf_am50=xlsread( 'drf.xls' 'am50' 'b4:u31' ); massf_am=xlsread( 'AM and AM50 Mass Fractions.xls' 'am', 'g1:g20' ); massf_am50=xlsread( 'AM and AM50 Mass Fractions.xls' 'am50' 'm1:m20' ); [arb1,sourcematrix] = xlsread( 'nb voxel count.xls' 'MATLABf' ); [arb2,safcellnums] = xlsread( 'saf indices.xls' 'Sheet1' ); energyindex = xlsread( 'saf indices.xls' 'Sheet1' 'e1:e1281' ); sourceindex = xlsread( 'saf indices.xls' 'Sheet1' 'f1:f1281' ); sourceabbrev = sourcematrix(:,3); fid_o_read = fopen( 'outputfilenames' 'r'); datafiles = textscan(fid_o_read, '%s', 'delimiter' '\n'); for outputnum=1:61*21 % Cycling through each output filename outputname = datafiles{1}{outputnum} fid = fopen(outputname, 'r'); % Reading text in from output file inputtext = textscan(fid, '%s', 'delimiter' '\n'); lines = length(inputtext{1}); placeholder=0; bonesite=0; format long e ; % Reading in ENERGY ----------------------------------------------------for i=1:lines energyflag = findstr( '1390sdef' ,inputtext{1}{i}); if energyflag == 1 energy = textscan(inputtext{1}{i}, '%*27c%n%*s%*s%*s%*s' ); break nd e end % ----------------------------------------------------------------------96

PAGE 97

for i=1:lines placeholder=placeholder+1; % Finding beginning of energy dependent fluences drfflag = findstr( 'cell 201' ,inputtext{1}{i}); if drfflag == 1 break end end % Reading in energy dependent fluences for every bone site for i=placeholder:lines drfflag2 = findstr( 'cell ,inputtext{1}{i}); if drfflag2 == 1 bonesite=bonesite+1; for j=1:28 fluence_temp(j,bonesite)=textscan(inputtext{1}{i+1+j}, '%*n%n%*n' ); end end if bonesite == 34 break end end % Multiplying the drf by the fluence at each energy for i=1:20 for j=1:28 drf_am_fluence{j,i}=fluence{j,i}.*drf_am(j,i).*massf_am(i); drf_am50_fluence{j,i}=fluence{j,i}.*drf_am50(j,i).*massf_am50(i); end end % Calculating the whole skeletan SAF for AM and AM50 SAF_am=(6.24142e+13/energy{1})*sum(sum(cell2mat(drf_am_fluence))); SAF_am50=(6.24142e+13/energy{1})*sum(sum(cell2mat(drf_am50_fluence))); xlswrite( 'Newborn SAFs female photons test',SAF_am,sourceabbrev{sourceindex(outputnum)},safcellnums{energyindex(out putnum),7}); xlswrite( 'Newborn SAFs female photons test',SAF_am50,sourceabbrev{sourceindex(outputnum)},safcellnums{energyindex(o utputnum),8}); end fclose( 'all'); toc/60 97

PAGE 98

MCNPX Output File Post-processing Code energy = xlsread( 'nb voxel count.xls' 'MATLABf' 'd1:d21' ); [arb1,sourcematrix] = xlsread( 'nb voxel count.xls' 'MATLABf' ); [arb2,safcellnums] = xlsread( 'saf indices.xls' 'Sheet1' ); energyindex = xlsread( 'saf indices.xls' 'Sheet1' 'e1:e1281' ); sourceindex = xlsread( 'saf indices.xls' 'Sheet1' 'f1:f1281' ); sourceabbrev = sourcematrix(:,3); outputfilenames = sprintf( 'outputfilenames' ); fid_o = fopen(outputfilenames, 'wt'); % Creating a file that lists all the output filenames in one column for i=1:length(sourceabbrev) for j=1:length(energy) fprintf(fid_o, '%s%0.0f%s\n' ,char(sourceabbrev(i)),char(j), 'fp.o' ); nd e end fclose(fid_o); fid_o_read = fopen( 'outputfilenames' 'r'); datafiles = textscan(fid_o_read, '%s', 'delimiter' '\n'); [arb3,cellnumber] = xlsread( 'Misc Output Info test.xls' 'Cell Numbers f' ); index=0; for i=1:61 for j=1:21 index=index+1; cellnum(index)=cellnumber(i,j); end end for outputnum=1:61*21 % Cycling through each output filename outputname = datafiles{1}{outputnum} fid = fopen(outputname, 'r'); % Reading text in from output file inputtext = textscan(fid, '%s', 'delimiter' '\n'); count6 = 0; count8 = 0; count4 = 0; counte = 0; format short e ; lines = length(inputtext{1}); % Reading in COMPUTER TIME ---------------------------------------------for i=1:lines 98

PAGE 99

timeflag = findstr( 'computer time =' ,inputtext{1}{i}); if timeflag == 1 comptime = textscan(inputtext{1}{i}, '%*16c%n%*s' ); break end end xlswrite( 'Misc Output Info test.xls' ,comptime, 'Computer Time f',cellnum{outputnum}); % ----------------------------------------------------------------------% Reading in ENERGY ----------------------------------------------------for i=1:lines energyflag = findstr( '1390sdef' ,inputtext{1}{i}); if energyflag == 1 energy = textscan(inputtext{1}{i}, '%*27c%n%*s%*s%*s%*s' ); break end end % ----------------------------------------------------------------------% MASS PROCESSING ------------------------------------------------------% Reading in organ masses for i=1:lines massflag = findstr( '3 1' ,inputtext{1}{i}); if massflag == 1 for j=1:156 organmass(j) = textscan(inputtext{1}{i+j1},'%*n%*n%*n%*n%*n%*n%n%*n%*n%*n' ); end break end 99

PAGE 100

end % General organ masses for i=1:57 genorganmass(i) = organmass(i); end % Total cartilage mass cartmass = 0; for i=1:31 cartmass = cartmass + organmass{57+i}; end % ----------------------------------------------------------------------% TALLY PROCESSING -----------------------------------------------------% Reading in the tally values (F6,*F8,F4) and ERRORS from output file for i=1:lines % Determining if it is an F6 or a *F8 tally ('mode p e' --> F8) tallytypeflag = findstr( '220mode p e' ,inputtext{1}{i}); if tallytypeflag == 1 break end end % If this is a *F8 tally if tallytypeflag == 1 % Reading through each line of the output file for i=1:lines % Finding the start of the tally values targetflag = findstr( '10000000' ,inputtext{1}{i}); % Reading in the tally values from the each line deemed a tally value line if targetflag == 1 count8 = count8+1; tally8_3column(count8,:) = textscan(inputtext{1}{i}, '%*n%n%*n%*n%*n%*n%n%*n%*n%*n%*n%n%*n%*n%*n%*n' ); error_3column(count8,:) = textscan(inputtext{1}{i}, '%*n%*n%n%*n%*n%*n%*n%n%*n%*n%*n%*n%n%*n%*n%*n' ); end end 100

PAGE 101

numtallies = 0; % Creating a one dimensional array of tallies from a two dimensional array for i=1:count8 for j=1:3 numtallies = numtallies+1; tally8temp(numtallies) = tally8_3column(i,j); errortemp(numtallies) = error_3column(i,j); nd e end % Deleting the last entry (tally6_3column(count6,3) = 0) for i=1:count8*3-1 tally8(i) = tally8temp(i); error8(i) = errortemp(i); end for j=1:57 SAF8{j} = tally8{j+34}/(genorganmass{j}*energy{1}); error(j)=error8(j+34); end carterr=error8(58+34); cartSAF=tally8{58+34}/cartmass; xlswrite( 'Newborn SAFs female photons test',SAF8(:),sourceabbrev{sourceindex(outputnum)},safcellnums{energyindex(ou tputnum),1}); xlswrite( 'Newborn SAFs female photons test',cartSAF,sourceabbrev{sourceindex(outputnum)},safcellnums{energyindex(ou tputnum),2}); xlswrite( 'Newborn SAFs female photons test',SAF8(:),sourceabbrev{sourceindex(outputnum)},safcellnums{energyindex(ou tputnum)-9,3}); xlswrite( 'Newborn SAFs female photons test',cartSAF,sourceabbrev{sourceindex(outputnum)},safcellnums{energyindex(ou tputnum)-9,4}); xlswrite( 'Newborn SAFs female photons (error) test',error(:),sourceabbrev{sourceindex(outputnum)},safcellnums{energyindex(o utputnum),1}); xlswrite( 'Newborn SAFs female photons (error) test',carterr,sourceabbrev{sourceindex(outputnum)},safcellnums{energyindex(ou tputnum),2}); xlswrite( 'Newborn SAFs female photons (error) test',error(:),sourceabbrev{sourceindex(outputnum)},safcellnums{energyindex(o utputnum)-9,3}); xlswrite( 'Newborn SAFs female photons (error) test',carterr,sourceabbrev{sourceindex(outputnum)},safcellnums{energyindex(ou tputnum)-9,4}); % If this is an F6 tally else 101

PAGE 102

% Reading through each line of the output file for i=1:lines % Finding the start of the tally values targetflag = findstr( '100000000' ,inputtext{1}{i}); % Reading in the tally values from the each line deemed a tally value line if targetflag == 1 count6 = count6+1; tally6_3column(count6,:) = textscan(inputtext{1}{i}, '%*n%n%*n%*n%*n%*n%n%*n%*n%*n%*n%n%*n%*n%*n%*n' ); error_3column(count6,:) = textscan(inputtext{1}{i}, '%*n%*n%n%*n%*n%*n%*n%n%*n%*n%*n%*n%n%*n%*n%*n' ); end end numtallies = 0; % Creating a one dimensional array of tallies from a two dimensional array for i=1:count6 for j=1:3 numtallies = numtallies+1; tally6temp(numtallies) = tally6_3column(i,j); errortemp(numtallies) = error_3column(i,j); nd e end % Deleting the last entry (tally6_3column(count6,3) = 0) for i=1:count6*3-1 tally6(i) = tally6temp(i) ; error6(i) = errortemp(i); end for j=1:57 SAF6{j} = tally6{j}/energy{1}; error(j)=error6(j); end carterr=error6(58); cartSAF=tally6{58}/cartmass; xlswrite( 'Newborn SAFs female photons test',SAF6(:),sourceabbrev{sourceindex(outputnum)},safcellnums{energyindex(ou tputnum),1}); xlswrite( 'Newborn SAFs female photons test',cartSAF,sourceabbrev{sourceindex(outputnum)},safcellnums{energyindex(ou tputnum),2}); xlswrite( 'Newborn SAFs female photons (error) test',error(:),sourceabbrev{sourceindex(outputnum)},safcellnums{energyindex(o utputnum),1}); 102

PAGE 103

103 xlswrite('Newborn SAFs female photons (error) test',carterr,sourceabbrev{sourceindex(outputnum)},safcellnums{energyindex(ou tputnum),2}); end fclose( 'all'); end

PAGE 104

LIST OF REFERENCES 1. American College of Radiology. Image Gently Campaign Named to Associations Advance America Honor Roll. 2009. http://www.acr.org/SecondaryMainMenuCategor ies/NewsPublications/FeaturedCategories/ CurrentACRNews/archive/ImageGentlyCampaignHonorRoll.aspx. Accessed 9/09. 2. The Alliance for Radiation Safety in Pediatric Imaging. Image gentlyStep Lightly. http://spr.affiniscape.com/associ ations/5364/ig/index.cfm?page=584 Accessed 9/09. 3. Harrison JD, Streffer C. The ICRP protection quantities, equivalent and effective dose: their basis and application. Radiat Prot Dosim 2007;127:12-18. 4. Hall EJ, Giaccia AJ. Radiobiology for the Radiologist, Sixth Edition Philadelphia, PA: Lippincott Williams & Wilkins; 2006. 5. Brownell GL, Ellett WH, Reddy AR. MIRD pa mphlet no. 3: absorbed fractions for photon dosimetry. J Nucl Med 1968;9(suppl):27-39. 6. National Council on Radiation Protec tion and Measurements (NCRP). Protection Against Neutron Radiation. Report No. 38. Bethesda, MD: NCRP; 1971. 7. Snyder WS, Ford MR, Warner GG, et al. MIRD pamphlet no. 5: estimates of absorbed fractions for monoenergetic pho ton sources uniformly distributed in various organs of a heterogeneous phantom. J Nucl Med 1969;10(suppl):5-52. 8. Snyder WS, Ford MR, Warner GG, et al. MIRD pamphlet no. 5, revised: estimates of absorbed fractions for monoenergetic photon sources uniformly distributed in various organs of a heterogeneous phantom. J Nucl Med 1978;10(suppl):5-67. 9. Cristy M, Eckerman KF. Specific Absorbed Fractions of Energy at Various Ages from Internal Photon Sources. I. Methods ORNL/TM-8381/V1. Oa k Ridge, TN: Oak Ridge National Laboratories; 1987. 10. Xu XG, Chao TC, Bozkurt A. VIP-man: an image-based whole-body adult male model constructed from color photographs of the Vi sible Human Project for multi-particle Monte Carlo calculations. Health Phys 2000;78:476-486. 11. Petoussi-Henss N, Zankl M, Fill U, Regulla D. The GSF family of voxel phantoms. Phys Med Biol 2002;47:89-106. 12. Lee C, Lodwick D, Hasenauer D, Williams JL Lee C, Bolch WE. Hybrid computational phantoms of the male and female newborn patient: NURBS-based whole-body models. Phys Med Biol 2007;52:3309-3333. 13. Nipper JC, Williams JL, Bolch WE. Creati on of two tomographic voxel models of paediatric patients in the first year of life. Phys Med Biol 2002;47:3143-3164. 104

PAGE 105

14. Pafundi D, Lee C, Watchman C, et al. An image-based skeletal tissue model for the ICRP reference newborn. Phys Med Biol 2009;54:4497-4531. 15. Rajon DA, Pichardo JC, Br indle JM, et al. Image segmenta tion of trabecular spongiosa by visual inspection of th e gradient magnitude. Phys Med Biol 2006;51:4447-4467. 16. Pafundi D, Rajon D, Jokisch D, Lee C, Bolch WE. An im age-based skeletal dosimetry model for the ICRP reference new born internal electron sources. Phys Med Biol In press. 17. X-5 Monte Carlo Team. MCNP A General Monte Carlo N-Particle Transport Code, Version 5. LA-UR-03-1987. Los Alamos National Laboratories; 2003. 18. International Commission on Radi ological Protection (ICRP). Basic Anatomical and Physiological Data for Use in Radi ological Protection: Reference Values. ICRP Publication 89. Oxford, U.K.: Pergamon Press; 2002. 19. Bolch WE, Eckerman KF, Sgouros G, Thomas SR MIRD pamphlet no. 21: a generalized schema for radiopharmaceutical dosimetry standardization of nomenclature. J Nucl Med 2009;50:477-484. 20. Treves ST. Pediatric Nuclear Medicine, Second Edition New York, NY: Springer-Verlag New York Inc.; 1995. 21. Arnold RW, Subramanian G, McAfee JG, Blai r RJ, Thomas FD. Comparison of tc-99m complexes for renal imaging. J Nucl Med 1975;16:357-367. 22. Evans E, Lythgoe MF, Anderson PJ, Smith Terry, Gordon I. Biokinetic behavior of technetium-99m-DMSA in children. J Nucl Med 1996;37:1331-1335. 23. Smith T, Evans K, Lythgoe MF, Anderson PJ, Gordon I. Radiation dosimetry of technetium-99m-DMSA in children. J Nucl Med 1996;37:1336-1342. 24. Faw RE, Shultis JK. Radiological Assessment: Sources and Doses. La Grange Park, IL: American Nuclear Society, Inc.; 1999. 25. International Commission on Ra diological Protection (ICRP). 2007 Recommendations of the International Commission on Radiological Protection. ICRP Publication 103. Ann ICRP. 2007;37:1-332. 26. Cherry SR, Sorenson JA, Phelps ME. Physics in Nuclear Medicine, Third Edition. Philadelphia, PA: Saunders; 2003. 27. Cristy M, Eckerman KF. Specific Absorbed Fractions of Energy at Various Ages from Internal Photon Sources. VI. Newborn ORNL/TM-8381/V6. Oak Ridge, TN: Oak Ridge National Laboratories; 1987. 105

PAGE 106

106 28. Treves ST, Davis RT, Fahey FH. Administer ed radiopharmaceutical doses in children: a survey of 13 pediatric hosp itals in North America. J Nucl Med 2008;49:1024-1027.

PAGE 107

BIOGRAPHICAL SKETCH Michael Brice Wayson was born in 1986 in Orla ndo, Florida to Mark and Niki Wayson. He has two younger brothers, Brant and Zachary. He has spent most of his life living in Brandon, FL, which is just outside Tampa, FL, bu t has also resided in Orlando, FL, West Palm Beach, FL, and Richmond, VA. He graduated fr om Bloomingdale Seni or High School in the spring of 2004. He graduated cum laude with his B.S. in nuclear engi neering at the University of Florida in December 2007 and is in the process of completing his M.S. in nuclear engineering Sciences with a specialty in Medical Physics at the University of Florida. He plans to earn a Ph.D. in Medical Physics at th e University of Florida upon co mpletion of the M.S. degree. Michael has a wide variety of extracurricular interests. He participates extensively in sporting events including football and basketba ll intramural competitions. He has played organized baseball, basketball, golf, track, cross country, and f ootball throughout his life. He enjoys traveling and has been to 21 of the 50 Unit ed States in addition to Jamaica, the Cayman Islands, Canada, and Italy. He especially en joys snow skiing and ha s been skiing at Copper Mountain, CO, Big Sky/Moonlight Basin, MT, a nd Whistler Mountain, BC, Canada. Another hobby Michael enjoys is piano performance and music composition. He was recently engaged to Ms. Leslie A nn Hooker who has conti nued to support him in his endeavor to complete his Master of Scien ce and Doctor of Philosophy degrees. She is whom this masters thesis and any subsequent works are ultimately for. 107