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Coleman D, Griffin KT, Dewji SA. Stylized versus voxel phantoms: quantification of internal organ chord length distances. Phys Med Biol 2023; 68. [PMID: 36780697 DOI: 10.1088/1361-6560/acbbb6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 02/13/2023] [Indexed: 02/15/2023]
Abstract
Dosimetric calculations, whether for radiation protection or nuclear medicine applications, are greatly influenced by the use of computational models of humans, called anthropomorphic phantoms. As anatomical models of phantoms have evolved and expanded, thus has the need for quantifying differences among each of these representations that yield variations in organ dose coefficients, whether from external radiation sources or internal emitters. This work represents an extension of previous efforts to quantify the differences in organ positioning within the body between a stylized and voxel phantom series. Where prior work focused on the organ depth distribution vis-à-vis the surface of the phantom models, the work described here quantifies the intra-organ and inter-organ distributions through calculation of the mean chord lengths. The revised Oak Ridge National Laboratory stylized phantom series and the University of Florida/National Cancer Institute voxel phantom series including a newborn, 1-, 5-, 10- and 15 year old, and adult phantoms were compared. Organ distances in the stylized phantoms were computed using a ray-tracing technique available through Monte Carlo radiation transport simulations in MCNP6. Organ distances in the voxel phantom were found using phantom matrix manipulation. Quantification of differences in organ chord lengths between the phantom series displayed that the organs of the stylized phantom series are typically situated farther away from one another than within the voxel phantom series. The impact of this work was to characterize the intra-organ and inter-organ distributions to explain the variations in updated internal dose coefficient quantities (i.e. specific absorbed fractions) while providing relevant data defining the spatial and volumetric organ distributions in the phantoms for use in subsequent internal dosimetric computations, with prospective relevance to patient-specific individualized dosimetry, as well as informing machine learning definition of organs using these reference models.
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Affiliation(s)
- D Coleman
- University of Wisconsin-Madison, Department of Medical Physics 1111 Highland Ave Rm 1005, Madison, WI 53705-2275, United States of America
| | - K T Griffin
- National Cancer Institute, Radiation Epidemiology Branch, 9609 Medical Center Drive MSC 9776, Bethesda, MD 20892-2590, United States of America.,Georgia Institute of Technology, Nuclear and Radiological Engineering and Medical Physics Programs, 770 State Street, Atlanta, GA 30332-0405, United States of America
| | - S A Dewji
- Georgia Institute of Technology, Nuclear and Radiological Engineering and Medical Physics Programs, 770 State Street, Atlanta, GA 30332-0405, United States of America
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2
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Dalak S, Asano E, Dewji S. ESTIMATION OF PROTECTION FACTORS FOR SURROGATE VEHICLE MODELS IN ENVIRONMENTAL CONTAMINATION SCENARIOS. RADIATION PROTECTION DOSIMETRY 2022; 198:1598-1610. [PMID: 36477339 DOI: 10.1093/rpd/ncac207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 08/28/2022] [Accepted: 09/22/2022] [Indexed: 06/17/2023]
Abstract
In the event of a nuclear or radiological incident involving the release of radioactive material, it may be critical to estimate doses to individuals who are transported through contaminated areas by vehicles. The radiation protection factor (RPF) for vehicles can be calculated to determine the level of shielding protection by the vehicle from external radiation sources. Prior studies evaluating RPFs demonstrate a lack of realistic vehicle configurations and the results cannot be extended directly to scenarios where a vehicle is surrounded by a contaminated environmental field. In this work, sex-averaged effective dose-rate coefficients were computed employing International Commission on Radiological Protection Publication 103 recommendations for radionuclides of interest and used to calculate the RPF as the ratio of unshielded to shielded dose for various radionuclides of interest in consequence management scenarios. Comparisons to dose reduction factors calculated using environmental measurement data from the 2011 Fukushima Daiichi nuclear incident were conducted to benchmark to experimental field measurements.
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Affiliation(s)
- Sena Dalak
- Department of Nuclear Engineering, Center for Nuclear Security Science and Policy Initiatives, Texas A&M University, 3133 TAMU, College Station 77843-3133, TX, USA
| | - Ethan Asano
- Nuclear and Radiological Engineering and Medical Physics Programs, Georgia Institute of Technology, 770 State St. NW, Atlanta 30332, GA, USA
| | - Shaheen Dewji
- Nuclear and Radiological Engineering and Medical Physics Programs, Georgia Institute of Technology, 770 State St. NW, Atlanta 30332, GA, USA
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Aziz L, Dewji S. UPDATED AGE-SPECIFIC EXTERNAL DOSE AND EXPOSURE RATE COEFFICIENTS FOR 131I PATIENT RELEASE. RADIATION PROTECTION DOSIMETRY 2022; 198:311-324. [PMID: 35437606 DOI: 10.1093/rpd/ncac049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 01/20/2022] [Accepted: 03/15/2022] [Indexed: 06/14/2023]
Abstract
Updated effective dose rate and exposure rate coefficients for age-specific receptors representing members of the public were computed for external exposures from age-specific patients administered 131I to treat thyroid dysfunction for patient release evaluation. Coefficients were compared to the simplified point source method described by United States Nuclear Regulatory Commission Regulatory Guide (RG) 8.39, which does not consider age-specific parameters, morphometry or time-dependent 131I biodistribution. Monte Carlo age-specific phantom simulations were correlated with modified continuous voiding patient biokinetic models approximating age-specific dose and exposure rates as a function of time postadministration. Dose rates resulted in an overapproximation by a factor of ~3 from differentiated thyroid cancer patients (5% uptake) and by ~2 from hyperthyroid patients (80%) at 8 h postadministration compared to RG8.39. This study provides a paradigm where age-specific morphometry and biokinetic integration must be jointly considered when developing patient release guidelines for 131I and future radionuclide therapies.
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Affiliation(s)
- L Aziz
- Department of Nuclear Engineering, Texas A&M University, 3133 TAMU, College Station, TX 77843-3133, USA
| | - S Dewji
- Nuclear and Radiological Engineering and Medical Physics Programs, Georgia Institute of Technology, 770 State Street, Atlanta, GA 30332-0405, USA
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Pang B, Becker F, Metz V. Monte-Carlo based investigation of individual dosimetry in deep geological repository for high-level nuclear waste with consideration of realistic body postures. ANN NUCL ENERGY 2021. [DOI: 10.1016/j.anucene.2021.108414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Rosenstrom A, Asano E, Griffin K, Lee C, Hooper D, Dewji S. Dose Coefficient Calculation for Use in Dosimetry Assessment of a Fission-Based Weapon. Radiat Res 2021; 196:272-283. [PMID: 34237146 DOI: 10.1667/rade-21-00012.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 06/03/2021] [Indexed: 11/03/2022]
Abstract
In the event of a fission-based weapon or improvised nuclear device (IND) detonation, dose coefficients can be harnessed to provide dose assessments for defense, emergency preparedness, and consequence management, as well as to prospectively inform the assessment of radiation biomarkers and development of medical prophylaxis countermeasures for defense and homeland security stakeholders and decision-makers. Although dose coefficients have previously been calculated for this group, they would apply specifically to the studied population, the 1945 Japanese cohort, after which their anthropomorphic computational phantoms were modeled. For this reason, applications to other populations may be limited, and instead, an assessment of a more standardized population is desired. We employed a series of computational human phantoms representing international reference individuals: UF/NCI voxel phantom series containing newborn, 1-, 5-, 10-, 15-, and 35-year-old males and females. Irradiation of the phantoms was simulated using the Monte Carlo N-Particle transport code to determine organ dose coefficients under four idealized irradiation geometries at three distances from the detonation hypocenter at Hiroshima and Nagasaki using DS02 free-in-air prompt neutron and photon fluence spectra. Through these simulations, age-specific dose coefficients were determined for individual organs. Various articulated PIMAL stylized phantoms were simulated as well, to estimate the effect of body posture on dose coefficients and determine the effect of posture on dosimetric estimation and reconstruction. Results additionally demonstrate that that 137Cs and the Watt fission spectrum are not ideal general surrogate sources for fission weapons, which may be considered for experimental testing of medical countermeasures. Supplementary data provided tabulates the culmination of organ dose-rate coefficients in this study.
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Affiliation(s)
- Andrew Rosenstrom
- Department of Nuclear Engineering, Center for Nuclear Security Science and Policy Initiatives Texas A&M University, College Station, Texas 77843-3133
| | - Ethan Asano
- Department of Nuclear Engineering, Center for Nuclear Security Science and Policy Initiatives Texas A&M University, College Station, Texas 77843-3133
| | - Keith Griffin
- National Cancer Institute, Rockville, Maryland 20850
| | - Choonsik Lee
- National Cancer Institute, Rockville, Maryland 20850
| | - David Hooper
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830
| | - Shaheen Dewji
- Department of Nuclear Engineering, Center for Nuclear Security Science and Policy Initiatives Texas A&M University, College Station, Texas 77843-3133
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Griffin KT, Cuthbert TA, Dewji SA, Lee C. Stylized versus voxel phantoms: a juxtaposition of organ depth distributions. Phys Med Biol 2020; 65:065007. [PMID: 32059205 DOI: 10.1088/1361-6560/ab7686] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
For external irradiation, the variability in organ dose estimation found between computational phantom generations arises particularly from the differences in organ positioning. This work represents the first effort to quantify the differences in organ depth below the body surface between a stylized and voxel phantom series. Herein, the revised Oak Ridge National Laboratory stylized phantom series and the University of Florida/National Cancer Institute voxel phantom series were compared. Both series include whole-body models of the newborn; the 1-, 5-, 10-, and 15-year-old; and the adult human. Organ depths from eight different directions applicable to external irradiation geometries were computed: antero-posterior, postero-anterior, left and right lateral, rotational, isotropic, cranial and caudal directions. Organ depths in the stylized phantoms were computed using a ray-tracing technique available through Monte Carlo radiation transport simulations in MCNP6. Organ depths in the voxel phantom were found using phantom matrix manipulation. Resultant organ depths for both series were plotted as distributions; available are twenty-four organs and two bone tissue distributions for each of six phantom ages and in each of the eight directional geometries. Quantitative data descriptors (e.g. mean and median depths) were also tabulated. For demonstration purposes, a literature review of relevant stylized versus voxel comparison works was performed to explore where the quantification of organ depth differences can provide further insight or evidence to study conclusions. The entire dataset of organ depth distributions and their data descriptors can be found in online supplementary files.
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Affiliation(s)
- Keith T Griffin
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD, United States of America
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Kofler C, Domal S, Satoh D, Dewji S, Eckerman K, Bolch WE. Organ and detriment-weighted dose rate coefficients for exposure to radionuclide-contaminated soil considering body morphometries that differ from reference conditions: adults and children. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2019; 58:477-492. [PMID: 31489486 DOI: 10.1007/s00411-019-00812-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 08/23/2019] [Indexed: 06/10/2023]
Abstract
The system of protection established by the International Commission on Radiological Protection (ICRP) provides a robust framework for ionizing radiation exposure justification, optimization, and dose limitation. The system is built upon fundamental concepts of a reference person, defined in ICRP Publication 89, and the radiation protection quantity effective dose, defined in ICRP Publication 103. For external exposures to radionuclide-contaminated soil, values of the organ dose rate coefficient (Gy/s per Bq/m2) and effective dose rate coefficient (Sv/s per Bq/m2) have been computed by several authors and national laboratories using ICRP-compliant reference phantoms-both stylized and voxelized. These coefficients are of great value in post-accident exposure assessments as seen in Japan following the 2011 Fukushima Daiichi nuclear power station disaster. Questions arise, however, among the general public regarding the accuracy of organ and effective dose estimates based upon reference phantom methodologies, especially for those individuals with height and/or total body mass that differ modestly or even substantially from the nearest age-matched reference person. In this pilot study, this issue is explored through use of the extended 351-member UF/NCI hybrid phantom library in which values of organ and detriment-weighted dose rate coefficients are computed for sex/height/mass-specific phantoms, and systematically compared to their values of the effective dose rate coefficient computed using corresponding reference phantoms. Results are given for monoenergetic photons, and then for some 33 different radionuclides, with all dose rate coefficient data provided in a series of electronic annexes. For environmentally relevant radionuclides such as 89Sr, 90Sr, 137Cs, and 131I, percent differences between the detriment-weighted dose rate coefficient computed using non-reference and the effective dose rate coefficient computed using reference phantoms vary only ± 5% for young children approximated by the reference 1-year-old phantom. With increased body size and age, the range of percent differences in these two quantities increases to + 7% to - 14% for the reference 5-year-old, to + 10% to - 27% for the reference 10-year-old, to + 33% to - 31% for the reference 15-year-old, and to + 15% to - 40% for male and female adults.
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Affiliation(s)
- Cameron Kofler
- Medical Physics Graduate Program, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Sean Domal
- Medical Physics Graduate Program, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Daiki Satoh
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Tokai-mura, Japan
| | - Shaheen Dewji
- Department of Nuclear Engineering, Texas A&M University, College Station, TX, USA
| | - Keith Eckerman
- Center for Radiation Protection Knowledge, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Wesley E Bolch
- J. Crayton Pruitt Family Department of Biomedical Engineering, Department of Biomedical Engineering, University of Florida, Gainesville, FL, 32611-6550, USA.
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Bales K, Dewji S. Comparison of Organ and Effective Photon Dose Coefficients for Reference Phantoms in Articulated and Upright Postures in Cranial and Caudal Irradiation Geometries. HEALTH PHYSICS 2019; 116:599-606. [PMID: 30624352 DOI: 10.1097/hp.0000000000000985] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Traditionally, dose estimations have been performed predominantly using anthropomorphic phantoms in an upright posture. However, an exclusively upright posture could reduce accuracy when estimating organ absorbed and effective doses for exposures in realistic postures. In this work, effective dose coefficients were computed using International Commission on Radiological Protection Publication 103 recommendations for monoenergetic photon plane sources (0.05-20 MeV) directed upward from below the feet (caudal) and downward from above the head (cranial) for articulated adult male and female stylized phantoms. The Monte Carlo radiation transport code and the Phantom With Moving Arms and Legs were used to calculate organ absorbed dose and effective dose coefficients for upright and two bent (45° and 90°) phantom postures. The resulting coefficients for the bent phantoms were compared to those for the upright phantoms to determine whether the upright phantoms provide a comparable and conservative estimate when conducting dose estimations/reconstructions. For the caudal source, most organs received higher doses when in a bent posture. For the cranial source, the breast, brain, and eyes received lower doses in the bent compared to the upright posture, while all other organs received higher doses. The effective doses for the articulated phantoms were higher than for the upright posture for both irradiation geometries, which could have implications when using the traditional model to estimate or reconstruct radiation doses during actual exposures.
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Affiliation(s)
- Kathryn Bales
- Oak Ridge National Laboratory, Center for Radiation Protection Knowledge, Oak Ridge, TN
- University of Tennessee-Knoxville, Department of Nuclear Engineering, Knoxville, TN
| | - Shaheen Dewji
- Department of Nuclear Engineering, Center for Nuclear Security Science and Policy Initiatives, Texas A&M University, College Station, TX
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Bales K, Dewji S, Sanchez E. Comparison of neutron organ and effective dose coefficients for PIMAL stylized phantom in bent postures in standard irradiation geometries. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2018; 57:375-393. [PMID: 30167867 DOI: 10.1007/s00411-018-0751-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 08/03/2018] [Indexed: 06/08/2023]
Abstract
Neutron dose coefficients for standard irradiation geometries have been reported in International Commission on Radiological Protection (ICRP) Publication 116 for the ICRP Publication 110 adult reference phantoms. In the present work, organ and effective dose coefficients have been calculated for a receptor in both upright and articulated (bent) postures representing more realistic working postures exposed to a mono-energetic neutron radiation field. This work builds upon prior work by Dewji and co-workers comparing upright and bent postures for exposure to mono-energetic photon fields. Simulations were conducted using the Oak Ridge National Laboratory's articulated stylized adult phantom, "Phantom wIth Moving Arms and Legs" (PIMAL) software package, and the Monte Carlo N-Particle (MCNP) version 6.1.1 radiation transport code. Organ doses were compared for the upright and bent (45° and 90°) phantom postures for neutron energies ranging from 1 × 10- 9 to 20 MeV for the ICRP Publication 116 external exposure geometries-antero-posterior (AP), postero-anterior (PA), and left and right lateral (LLAT, RLAT). Using both male and female phantoms, effective dose coefficients were computed using ICRP Publication 103 methodology. The resulting coefficients for articulated phantoms were compared to those of the upright phantom. Computed organ and effective dose coefficients are discussed as a function of neutron energy, phantom posture, and source irradiation geometry. For example, it is shown here that for the AP and PA irradiation geometries, the differences in the organ coefficients between the upright and bent posture become more pronounced with increasing bending angle. In the AP geometry, the brain dose coefficients are expectedly higher in the bent postures than in the upright posture, while all other organs have lower dose coefficients, with the thyroid showing the greatest difference. Overall, the effective dose estimated for the upright phantom is more conservative than that for the articulated phantom, which may have ramifications in the estimation or reconstruction of radiation doses.
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Affiliation(s)
- K Bales
- Oak Ridge National Laboratory, Center for Radiation Protection Knowledge, Oak Ridge, TN, USA
- Department of Nuclear Engineering, University of Tennessee, Knoxville, Knoxville, TN, USA
| | - S Dewji
- Oak Ridge National Laboratory, Center for Radiation Protection Knowledge, Oak Ridge, TN, USA.
| | - E Sanchez
- Oak Ridge National Laboratory, Center for Radiation Protection Knowledge, Oak Ridge, TN, USA
- Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
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Dewji SA, Bales K, Griffin K, Lee C, Hiller M. Age-dependent comparison of monoenergetic photon organ and effective dose coefficients for pediatric stylized and voxel phantoms submerged in air. Phys Med Biol 2018; 63:175019. [PMID: 30051886 DOI: 10.1088/1361-6560/aad64e] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Dose rate coefficients computed using the University of Florida-National Cancer Institute pediatric series of voxel phantoms were compared with values computed using the Oak Ridge National Laboratory pediatric stylized phantoms in an air submersion exposure geometry. Simulations were conducted comparing phantoms classified within five ages: newborn, 1-year-old, 5-year-old, 10-year-old, and 15-year-old for both male and female sexes. This is a continuation of previous work comparing monoenergetic photon organ dose rate coefficients, as defined by ICRP Publication 103, for the male and female adult phantoms. With both the male and female data computed for each pediatric phantom age, effective dose rate coefficients and ratios were computed for voxel and stylized phantoms. Organ dose rate coefficients for the pediatric phantoms and ratios of organ dose rates for the voxel and stylized phantoms are provided for eight monoenergetic photon energies ranging from 30 keV to 5 MeV. Analysis of the contribution of the organs to effective dose is also provided. Comparison of effective dose rates between the voxel and stylized phantoms was within 5% between 500 keV and 5 MeV and within 10% between 70 keV and 5 MeV for phantoms >1-year-old. Stylized newborn effective dose rates were consistently ~20% higher than the voxel counterpart, over all energies.
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Affiliation(s)
- Shaheen Azim Dewji
- Oak Ridge National Laboratory, Center for Radiation Protection Knowledge, PO Box 2008 MS 6038, Oak Ridge, TN 37831-6038, United States of America. Author to whom any correspondence should be addressed
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