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Carter LM, Bellamy MB, Choi C, Kim CH, Bolch WE, Jokisch D, Kesner AL. Influence of Body Posture on Internal Organ Dosimetry: Radiocesium Exposure Modeling Using Novel Posture-dependent Mesh Computational Phantoms. HEALTH PHYSICS 2023; 125:137-146. [PMID: 37195207 PMCID: PMC10313736 DOI: 10.1097/hp.0000000000001701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
ABSTRACT Current practice in reference internal dosimetry assumes a fixed upright standing posture is maintained throughout the dose-integration period. Recently, the mesh-type ICRP adult reference computational phantoms were transformed into different body postures (e.g., sitting, squatting) for use in occupational dose reconstruction applications. Here, for the first time, we apply this phantom series to the study of organ dose estimates following radionuclide intake. We consider the specific cases of 137 Cs and 134 Cs ingestion (accidental/occupational intake) with attention to variability in absorbed dose as a function of posture. The ICRP Publication 137 systemic biokinetic model for soluble cesium ingestion was used to compute organ-level time-integrated activity coefficients for reference adults, over a 50-y dose-integration period, for 134 Cs and 137 Cs (and its radioactive progeny 137m Ba). Mean posture time-allocations (h d -1 for standing, sitting, and lying) were taken from published survey data. In accord with modern dosimetry formalisms (e.g., MIRD, ICRP), a posture weighting factor was introduced that accounts for the fraction of time spent within each independent posture. Absorbed dose coefficients were computed using PHITS Monte Carlo simulations. ICRP 103 tissue weighting factors were applied along with the posture weighting factors to obtain committed effective dose per unit intake (Sv Bq -1 ). For 137 Cs ingestion, most organ absorbed dose coefficients were negligibly to marginally higher (< ~3%) for sitting or crouched (lying fetal/semi-fetal) postures maintained over the dose commitment period, relative to the upright standing posture. The committed effective dose coefficients were 1.3 × 10 -8 Sv Bq -1 137 Cs for standing, sitting, or crouched postures; thus, the posture-weighted committed effective dose was not significantly different than the committed effective dose for a maintained upright standing posture. For 134 Cs ingestion, most organ absorbed dose coefficients for the sitting and crouched postures were significantly larger than the standing posture, but the differences were still considered minor (< ~8% for most organs). The committed effective dose coefficients were 1.2 × 10 -8 Sv Bq -1 134 Cs for the standing posture and 1.3 × 10 -8 Sv Bq -1 134 Cs for the sitting or crouched posture. The posture-weighted committed effective dose was 1.3 × 10 -8 Sv Bq -1 134 Cs. Body posture has minor influence on organ-level absorbed dose coefficients and committed effective dose for ingestion of soluble 137 Cs or 134 Cs.
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Affiliation(s)
- LM Carter
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - MB Bellamy
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - C Choi
- J. Crayton Pruitt Department of Nuclear Engineering, University of Florida, Gainesville, FL, USA
| | - CH Kim
- Department of Nuclear Engineering, Hanyang University, Seoul, Korea
| | - WE Bolch
- J. Crayton Pruitt Department of Nuclear Engineering, University of Florida, Gainesville, FL, USA
| | - D Jokisch
- Department of Physics, Francis Marion University, Florence, SC, USA
- Center for Radiation Protection Knowledge, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - AL Kesner
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, USA
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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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Choi C, Shin B, Yeom YS, Nguyen TT, Han H, Kim S, Son G, Moon S, Kim H, Kim CH, Bolch WE, Jokisch DW, Lee C, Chung BS. Development of alimentary tract organs for ICRP pediatric mesh-type reference computational phantoms. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2022; 42:031508. [PMID: 35921807 DOI: 10.1088/1361-6498/ac8683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 08/03/2022] [Indexed: 06/15/2023]
Abstract
In line with the activities of Task Group 103 under the International Commission on Radiological Protection (ICRP), the present study was conducted to develop a new set of alimentary tract organs consisting of the oral cavity, oesophagus, stomach, small intestine, and colon for the newborn, 1 year-old, 5 year-old, 10 year-old, and 15 year-old males and females for use in the pediatric mesh-type reference computational phantoms (MRCPs). The developed alimentary tract organs of the pediatric MRCPs, while nearly preserving the original topology and shape of those of the pediatric voxel-type reference computational phantoms (VRCPs) of ICRPPublication 143, present considerable anatomical improvement and include all micrometre-scale target and source regions as prescribed in ICRPPublication 100. To investigate the dosimetric impact of the developed alimentary tract organs, organ doses and specific absorbed fractions were computed for certain external exposures to photons and electrons and internal exposures to electrons, respectively, which were then compared with the values computed using the current ICRP models (i.e. pediatric VRCPs and ICRP-100 stylised models). The results showed that for external exposures to penetrating radiations (i.e. photons >0.04 MeV), there was generally good agreement between the compared values, within a 10% difference, except for the oral mucosa. For external exposures to weakly penetrating radiations (i.e. low-energy photons and electrons), there were significant differences, up to a factor of ∼8300, owing to the geometric difference caused by the anatomical enhancement in the MRCPs. For internal exposures of electrons, there were significant differences, the maximum of which reached a factor of ∼73 000. This was attributed not only to the geometric difference but also to the target mass difference caused by the different luminal content mass and organ shape.
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Affiliation(s)
- Chansoo Choi
- Department of Nuclear Engineering, Hanyang University, Seoul, Republic of Korea
| | - Bangho Shin
- Department of Nuclear Engineering, Hanyang University, Seoul, Republic of Korea
| | - Yeon Soo Yeom
- Department of Radiation Convergence Engineering, Yonsei University, Wonju, Republic of Korea
| | - Thang Tat Nguyen
- School of Nuclear Engineering and Environmental Physics, Hanoi University of Science and Technology, Hanoi, Vietnam
| | - Haegin Han
- Department of Nuclear Engineering, Hanyang University, Seoul, Republic of Korea
| | - Suhyeon Kim
- Department of Nuclear Engineering, Hanyang University, Seoul, Republic of Korea
| | - Gahee Son
- Department of Nuclear Engineering, Hanyang University, Seoul, Republic of Korea
| | - Sungho Moon
- Department of Nuclear Engineering, Hanyang University, Seoul, Republic of Korea
| | - Hyeonil Kim
- Department of Nuclear Engineering, Hanyang University, Seoul, Republic of Korea
| | - Chan Hyeong Kim
- Department of Nuclear Engineering, Hanyang University, Seoul, Republic of Korea
| | - Wesley E Bolch
- J Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, United States of America
| | - Derek W Jokisch
- Department of Physics and Engineering, Francis Marion University, Florence, SC, United States of America
- Center for Radiation Protection Knowledge, Oak Ridge National Laboratory, Oak Ridge, TN, United States of America
| | - Choonsik Lee
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States of America
| | - Beom Sun Chung
- Department of Anatomy, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
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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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Akhavanallaf A, Fayad H, Salimi Y, Aly A, Kharita H, Al Naemi H, Zaidi H. An update on computational anthropomorphic anatomical models. Digit Health 2022; 8:20552076221111941. [PMID: 35847523 PMCID: PMC9277432 DOI: 10.1177/20552076221111941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 06/19/2022] [Indexed: 11/15/2022] Open
Abstract
The prevalent availability of high-performance computing coupled with validated
computerized simulation platforms as open-source packages have motivated
progress in the development of realistic anthropomorphic computational models of
the human anatomy. The main application of these advanced tools focused on
imaging physics and computational internal/external radiation dosimetry
research. This paper provides an updated review of state-of-the-art developments
and recent advances in the design of sophisticated computational models of the
human anatomy with a particular focus on their use in radiation dosimetry
calculations. The consolidation of flexible and realistic computational models
with biological data and accurate radiation transport modeling tools enables the
capability to produce dosimetric data reflecting actual setup in clinical
setting. These simulation methodologies and results are helpful resources for
the medical physics and medical imaging communities and are expected to impact
the fields of medical imaging and dosimetry calculations profoundly.
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Affiliation(s)
- Azadeh Akhavanallaf
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva, Switzerland
| | - Hadi Fayad
- Hamad Medical Corporation, Doha, Qatar
- Weill Cornell Medicine, Doha, Qatar
| | - Yazdan Salimi
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva, Switzerland
| | - Antar Aly
- Hamad Medical Corporation, Doha, Qatar
- Weill Cornell Medicine, Doha, Qatar
| | | | - Huda Al Naemi
- Hamad Medical Corporation, Doha, Qatar
- Weill Cornell Medicine, Doha, Qatar
| | - Habib Zaidi
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva, Switzerland
- Geneva University Neurocenter, Geneva University, Geneva, Switzerland
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
- Department of Nuclear Medicine, University of Southern Denmark, Odense, Denmark
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Cheon B, Lee SH, Han MC, Min CH, Han H, Kim CH, Kim JS. Development of a novel program for conversion from tetrahedral-mesh-based phantoms to DICOM dataset for radiation treatment planning: TET2DICOM. J Appl Clin Med Phys 2022; 23:e13448. [PMID: 34633736 PMCID: PMC8803294 DOI: 10.1002/acm2.13448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 09/22/2021] [Accepted: 09/25/2021] [Indexed: 11/11/2022] Open
Abstract
PURPOSE Tetrahedral mesh (TM)-based computational human phantoms have recently been developed for evaluation of exposure dose with the merit of precisely representing human anatomy and the changing posture freely. However, conversion of recently developed TM phantoms to the Digital Imaging and Communications in Medicine (DICOM) file format, which can be utilized in the clinic, has not been attempted. The aim of this study was to develop a technique, called TET2DICOM, to convert the TM phantoms to DICOM datasets for accurate treatment planning. MATERIALS AND METHODS The TM phantoms were sampled in voxel form to generate the DICOM computed tomography images. The DICOM-radiotherapy structure was defined based on the contour data. To evaluate TET2DICOM, the shape distortion of the TM phantoms during the conversion process was assessed, and the converted DICOM dataset was implemented in a commercial treatment planning system (TPS). RESULTS The volume difference between the TM phantoms and the converted DICOM dataset was evaluated as less than about 0.1% in each organ. Subsequently, the converted DICOM dataset was successfully implemented in MIM (MIM Software Inc., Cleveland, USA, version 6.5.6) and RayStation (RaySearch Laboratories, Stockholm, Sweden, version 5.0). Additionally, the various possibilities of clinical application of the program were confirmed using a deformed TM phantom in various postures. CONCLUSION In conclusion, the TM phantom, currently the most advanced computational phantom, can be implemented in a commercial TPS and this technique can enable various TM-based applications, such as evaluation of secondary cancer risk in radiotherapy.
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Affiliation(s)
- Bo‐Wi Cheon
- Department of Radiation Convergence EngineeringYonsei UniversityWonjuKorea
| | - Se Hyung Lee
- Department of Nuclear EngineeringHanyang UniversitySeoulKorea
- Department of Radiation OncologyBundang Jesaeng General HospitalSeongnamKorea
| | - Min Cheol Han
- Department of Radiation OncologyYonsei University College of MedicineSeoulKorea
| | - Chul Hee Min
- Department of Radiation Convergence EngineeringYonsei UniversityWonjuKorea
| | - Haegin Han
- Department of Nuclear EngineeringHanyang UniversitySeoulKorea
| | - Chan Hyeong Kim
- Department of Nuclear EngineeringHanyang UniversitySeoulKorea
| | - Jin Sung Kim
- Department of Radiation OncologyYonsei University College of MedicineSeoulKorea
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Choi C, Shin B, Yeom YS, Nguyen TT, Han H, Ha S, Chung BS, Bolch WE, Kim CH. Development of paediatric mesh-type reference computational phantom series of International Commission on Radiological Protection. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2021; 41:S160-S170. [PMID: 34082408 DOI: 10.1088/1361-6498/ac0801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 06/03/2021] [Indexed: 06/12/2023]
Abstract
Very recently, Task Group 103 of the International Commission on Radiological Protection (ICRP) completed the development of the paediatric mesh-type reference computational phantoms (MRCPs) comprising ten phantoms (newborn, one year-old, five year-old, ten year-old, and fifteen year-old males and females). The paediatric MRCPs address the limitations of ICRPPublication 143's paediatric reference computational phantoms, which are in voxel format, stemming from the nature of the voxel geometry and the limited voxel resolutions. The paediatric MRCPs were constructed by converting the voxel-type reference phantoms to a high-quality mesh format with substantial enhancements in the detailed anatomy of the small and complex organs and tissues (e.g. bones, lymphatic nodes, and extra-thoracic region). Besides, the paediatric MRCPs were developed in consideration of the intra-organ blood contents and by modelling the micron-thick target and source regions of the skin, lens, urinary bladder, alimentary tract organs, and respiratory tract organs prescribed by the ICRP. For external idealised exposures, the paediatric MRCPs provide very similar effective dose coefficients (DCEs) to those from the ICRP-143 phantoms but significantly different values for weakly penetrating radiations (e.g. the difference of ∼20 000 times for 10 keV electron beams). This paper introduces the developed paediatric MRCPs with a brief explanation of the construction process. Then, it discusses their computational performance in Geant4, PHITS, and MCNP6 in terms of memory usage and computation speed and their impact on dose calculations by comparing their calculated values of DCEs for external exposures with those of the voxel-type reference phantoms.
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Affiliation(s)
- Chansoo Choi
- Department of Nuclear Engineering, Hanyang University, Seoul, Republic of Korea
| | - Bangho Shin
- Department of Nuclear Engineering, Hanyang University, Seoul, Republic of Korea
| | - Yeon Soo Yeom
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institute of Health, Bethesda, MD, United States of America
| | - Thang Tat Nguyen
- Department of Nuclear Engineering and Environmental Physics, Hanoi University of Science and Technology, Hanoi, Vietnam
| | - Haegin Han
- Department of Nuclear Engineering, Hanyang University, Seoul, Republic of Korea
| | - Sangseok Ha
- Department of Nuclear Engineering, Hanyang University, Seoul, Republic of Korea
| | - Beom Sun Chung
- Department of Anatomy, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - Wesley E Bolch
- J Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, United States of America
| | - Chan Hyeong Kim
- Department of Nuclear Engineering, Hanyang University, Seoul, Republic of Korea
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Choi C, Shin B, Yeom YS, Han H, Ha S, Moon S, Son G, Nguyen TT, Kim CH, Chung BS, Bolch WE. Development of skeletal systems for ICRP pediatric mesh-type reference computational phantoms. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2021; 41:139-161. [PMID: 33401263 DOI: 10.1088/1361-6498/abd88d] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 01/05/2021] [Indexed: 06/12/2023]
Abstract
In 2016, the International Commission on Radiological Protection (ICRP) launched Task Group 103 (TG 103) for the explicit purpose of developing a new generation of adult and pediatric reference computational phantoms, named 'mesh-type reference computational phantoms (MRCPs)', that can overcome the limitations of voxel-type reference computational phantoms (VRCPs) of ICRPPublications 110and143due to their finite voxel resolutions and the nature of voxel geometry. After completing the development of the adult MRCPs, TG 103 has started the development of pediatric MRCPs comprising 10 phantoms (male and female versions of the reference newborn, 1-year-old, 5-year-old, 10-year-old, and 15-year-old). As part of the TG 103 project, within the present study, the skeletal systems, one of the most important and complex organ systems of the body, were developed for each phantom age and sex. The developed skeletal systems, while closely preserving the original bone topology of the pediatric VRCPs, present substantial improvements in the anatomy of complex and/or small bones. In order to investigate the dosimetric impact of the developed skeletons, the average absorbed doses and the specific absorbed fractions for radiosensitive skeletal tissues (i.e. active marrow and bone endosteum) were computed for some selected external and internal exposure cases, which were then compared with those calculated with the skeletons of pediatric VRCPs. The comparison result showed that the dose values of the pediatric MRCPs were generally similar to those of the pediatric VRCPs for highly penetrating radiations (e.g. photons >200 keV); however, for weakly penetrating radiations (e.g. photons ⩽200 keV and electrons), significant differences up to a factor of 140 were observed.
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Affiliation(s)
- Chansoo Choi
- Department of Nuclear Engineering, Hanyang University, Seoul, Republic of Korea
| | - Bangho Shin
- Department of Nuclear Engineering, Hanyang University, Seoul, Republic of Korea
| | - Yeon Soo Yeom
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States of America
| | - Haegin Han
- Department of Nuclear Engineering, Hanyang University, Seoul, Republic of Korea
| | - Sangseok Ha
- Department of Nuclear Engineering, Hanyang University, Seoul, Republic of Korea
| | - Sungho Moon
- Department of Nuclear Engineering, Hanyang University, Seoul, Republic of Korea
| | - Gahee Son
- Department of Nuclear Engineering, Hanyang University, Seoul, Republic of Korea
| | - Thang Tat Nguyen
- School of Nuclear Engineering and Environmental Physics, Hanoi University of Science and Technology, Hanoi, Vietnam
| | - Chan Hyeong Kim
- Department of Nuclear Engineering, Hanyang University, Seoul, Republic of Korea
| | - Beom Sun Chung
- Department of Anatomy, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - Wesley E Bolch
- J Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, United States of America
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Yeom YS, Griffin K, Han H, Choi C, Shin B, Nguyen TT, Kim CH, Lee C. Dose conversion coefficients for neutron external exposures with five postures: walking, sitting, bending, kneeling, and squatting. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2021; 60:317-328. [PMID: 33704559 PMCID: PMC9923510 DOI: 10.1007/s00411-021-00900-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 02/20/2021] [Indexed: 06/12/2023]
Abstract
In a previous study, posture-dependent dose coefficients (DCs) for photon external exposures were calculated using the adult male and female mesh-type reference computational phantoms (MRCPs) of the International Commission on Radiological Protection (ICRP) that had been transformed into five non-standing postures (i.e. walking, sitting, bending, kneeling, and squatting). As an extension, the present study was conducted to establish another DC dataset for external exposures to neutrons by performing Monte Carlo radiation transport simulations with the adult male and female MRCPs in the five non-standing postures. The resulting dataset included the DCs for absorbed doses (i.e., organ/tissue-averaged absorbed doses) delivered to 29 individual organs/tissues, and for effective doses for neutron energies ranging from 10-9 to 104 MeV in six irradiation geometries: antero-posterior (AP), posteroanterior (PA), left-lateral (LLAT), right-lateral (RLAT), rotational (ROT), and isotropic (ISO) geometries. The comparison of DCs for the non-standing MRCPs with those of the standing MRCPs showed significant differences. In the lateral irradiation geometries, for example, the standing MRCPs overestimate the breast DCs of the squatting MRCPs by up to a factor of 4 due to the different arm positions but underestimate the gonad DCs by up to about 17 times due to the different leg positions. The impact of different postures on effective doses was generally less than that on organ doses but still significant; for example, the standing MRCPs overestimate the effective doses of the bending MRCPs only by 20% in the AP geometry at neutron energies less than 50 MeV, but underestimate those of the kneeling MRCPs by up to 40% in the lateral geometries at energies less than 0.1 MeV.
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Affiliation(s)
- Yeon Soo Yeom
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD, 20850, USA
| | - Keith Griffin
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD, 20850, USA
| | - Haegin Han
- Department of Nuclear Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 04763, Korea
| | - Chansoo Choi
- Department of Nuclear Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 04763, Korea
| | - Bangho Shin
- Department of Nuclear Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 04763, Korea
| | - Thang Tat Nguyen
- School of Nuclear Engineering and Environmental Physics, Hanoi University of Science and Technology, 1 Dai Co Viet road, Hai Ba Trung District, Hanoi, Vietnam
| | - Chan Hyeong Kim
- Department of Nuclear Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 04763, Korea.
| | - Choonsik Lee
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD, 20850, USA
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Sivabhaskar S, Perry A, Dewji S. Comparison of Neutron Organ and Effective Dose Coefficients for PIMAL Stylized Phantoms in Bent Postures in Cranial and Caudal Irradiation Geometries. HEALTH PHYSICS 2021; 120:559-572. [PMID: 33470713 DOI: 10.1097/hp.0000000000001382] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
ABSTRACT Radiation dose estimations in the human body are performed using computational reference phantoms, which are anatomical representations of the human body. In previous studies, dose reconstructions have been performed focusing primarily on phantoms in an upright posture, which limits the accuracy of the dose estimations for postures observed in realistic work settings. In this work, the International Commission on Radiological Protection (ICRP) Publication 103 recommendations for monoenergetic neutron plane sources directed downward from above the head (cranial) and upward from below the feet (caudal) for adult female and male reference phantoms were used to calculate organ absorbed and effective dose coefficients. The Phantom with Moving Arms and Legs (PIMAL) and the Monte Carlo N-Particle (MCNP) radiation transport code were used to compute organ-absorbed dose and effective dose coefficients for the upright, half-bent (45°), and full-bent (90°) phantom postures. The doses calculated for each of the articulated positions were compared to those calculated for the upright posture by computing the ratios of the coefficients (45°/upright and 90°/upright). These ratios were used to assess the effectiveness of upright phantoms in providing a comparable estimate when conducting dose estimations and dose reconstructions for articulated positions. This work compiling neutron cranial and caudal posture-specific dose coefficients completes the series of dose coefficients computed for posture-specific ICRP Publication 116 irradiation geometries for monoenergetic photons and neutrons, in addition to cranial and caudal monoenergetic photons. Results reported demonstrated that organ-absorbed dose coefficients for most of the organs in the CRA and CAU irradiation geometries were significantly higher for the bent phantoms than for the upright phantom. Since the upright phantom underestimates the organ-absorbed dose, this demonstrates the impact of posture while performing dose calculations. Organ doses reported in past neutron dose coefficient data were found to omit effects from neutron resonances at energies of 0.435, 1.0, and 3.21 MeV from 16O in tissue. Reported data notes as high as 60% underestimation for neutron organ-absorbed doses, specifically at the neutron resonance energy region omitted by smoothing. Ongoing studies are examining the effect of resonances on reported neutron organ-absorbed dose coefficients in ICRP 116 geometries.
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Affiliation(s)
| | - Alexander Perry
- Department of Nuclear Engineering, Texas A&M University, College Station, TX 77843
| | - Shaheen Dewji
- Department of Nuclear Engineering, Texas A&M University, College Station, TX 77843
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