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New thyroid models for ICRP pediatric mesh-type reference computational phantoms
염연수,최찬수,신방호,김수현,한혜진,문성호,손가희,김현일,Nguyen Thang Tat,정범선,이세형,김찬형 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.12
As part of the ICRP Task Group 103 project, we developed ten thyroid models for the pediatric mesh-type reference computational phantoms (MRCPs). The thyroid is not only a radiosensitive target organ needed for effective dose calculation but an important source region particularly for radioactive iodines. The thyroid models for the pediatric MRCPs were constructed by converting those of the pediatric voxel-type reference computational phantoms (VRCPs) in ICRP Publication 143 to a high-quality mesh format, faithfully maintaining their original topology. At the same time, we improved several anatomical parameters of the thyroid models for the pediatric MRCPs, including the mass, overlying tissue thickness, location, and isthmus dimensions. Absorbed doses to the thyroid for the pediatric MRCPs for photon external exposures were calculated and compared with those of the pediatric VRCPs, finding that the differences between the MRCPs and VRCPs were not significant except for very low energies (<0.03 MeV). Specific absorbed fractions (target ) thyroid) for photon internal exposures were also compared, where significant differences were frequently observed especially for the target organs/tissues close to the thyroid (e.g., a factor of ~1.2e~327 for the thymus as a target) due mainly to anatomical improvement of the MRCP thyroid models.
Iodine-131 S Values for Use in Organ Dose Estimation of Korean Patients in Radioiodine Therapy
염연수,신방호,최찬수,한혜진,김찬형 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.2
In the present study, iodine-131 S values (rT ) thyroid) were calculated for 30 target organs and tissuesusing the most recently developed Korean reference computational phantoms. The calculated S valueswere then compared with those of the International Commission on Radiological Protection (ICRP)reference computational phantoms to investigate the dosimetric impact of the Korean S values againstthose of the ICRP reference phantoms. The results showed significant differences in the S values due tothe different anatomical/morphological characteristics between the Korean and ICRP reference phantoms. Most target organs/tissues showed that the S values of the Korean reference phantoms are lowerthan those of the ICRP reference phantoms, by up to about 4 times (male spleen and female thymus). Exceptionally, three target organs/tissues (gonads, thyroid, and extrathoracic region) showed that the Svalues of the Korean reference phantoms are greater, by 1.5e3.7 times. We expect that the S valuescalculated in the present study will be beneficially used to estimate organ/tissue doses of Korean patientsunder radioiodine therapy
염연수,최찬수,한혜진,이한진,신방호,Thang Tat Nguyen,한민철,이춘식,김찬형 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.3
In the present study, we established a comprehensive dataset of dose coefficients (DCs) of the new meshtypeICRP reference computational phantoms (MRCPs) for idealized external exposures of photons andelectrons with the Geant4 code. Subsequently, the DCs for the nine organs/tissues, calculated for theirthin radiosensitive target regions, were compared with the values calculated by averaging the absorbeddoses over the entire organ/tissue regions to observe the influence of the thin sensitive regions on dosecalculations. The result showed that the influences for both photons and electrons were generallyinsignificant for the majority of organs/tissues, but very large for the skin and eye lens, especially forelectrons. Furthermore, the large influence for the skin eventually affected the effective dose calculationsfor electrons. The DCs of the MRCPs also were compared with the current ICRP-116 values produced withthe current ICRP-110 reference phantoms. The result showed that the DCs for the majority of organs/tissues and effective dose were generally similar to the ICRP-116 values for photons, except for very lowenergies; however, for electrons, significant differences from the ICRP-116 values were found in the DCs,particularly for superficial organs/tissues and skeletal tissues, and also for effective dose.