Kim Han Sung, Yeom Yeon Soo, Nguyen Thang Tat, Choi Chansoo, Han Min Cheol, Lee Jai Ki, Kim Chan Hyeong, Zankl Maria, Petoussi-Henss Nina, Bolch Wesley E, Lee Choonsik, Qiu Rui, Eckerman Keith, Chung Beom Sun
Department of Nuclear Engineering, Hanyang University, Seoul, Korea.
Phys Med Biol. 2017 Mar 21;62(6):2132-2152. doi: 10.1088/1361-6560/aa5b72. Epub 2017 Jan 23.
It is not feasible to define very small or complex organs and tissues in the current voxel-type adult reference computational phantoms of the International Commission on Radiological Protection (ICRP), which limit dose coefficients for weakly penetrating radiations. To address the problem, the ICRP is converting the voxel-type reference phantoms into mesh-type phantoms. In the present study, as a part of the conversion project, the micrometer-thick target and source regions in the alimentary and respiratory tract systems as described in ICRP Publications 100 and 66 were included in the mesh-type ICRP reference adult male and female phantoms. In addition, realistic lung airway models were simulated to represent the bronchial (BB) and bronchiolar (bb) regions. The electron specific absorbed fraction (SAF) values for the alimentary and respiratory tract systems were then calculated and compared with the values calculated with the stylized models of ICRP Publications 100 and 66. The comparisons show generally good agreement for the oral cavity, oesophagus, and BB, whereas for the stomach, small intestine, large intestine, extrathoracic region, and bb, there are some differences (e.g. up to ~9 times in the large intestine). The difference is mainly due to anatomical difference in these organs between the realistic mesh-type phantoms and the simplified stylized models. The new alimentary and respiratory tract models in the mesh-type ICRP reference phantoms preserve the topology and dimensions of the voxel-type ICRP phantoms and provide more reliable SAF values than the simplified models adopted in previous ICRP Publications.
在国际放射防护委员会（ICRP）当前的体素型成人参考计算体模中，定义非常小或复杂的器官和组织是不可行的，这些体模限制了弱穿透辐射的剂量系数。为了解决这个问题，ICRP正在将体素型参考体模转换为网格型体模。在本研究中，作为转换项目的一部分，ICRP出版物100和66中描述的消化道和呼吸道系统中微米厚的靶区和源区被纳入网格型ICRP参考成年男性和女性体模。此外，还模拟了逼真的肺气道模型来代表支气管（BB）和细支气管（bb）区域。然后计算了消化道和呼吸道系统的电子比吸收分数（SAF）值，并与ICRP出版物100和66中的简化模型计算的值进行了比较。比较结果表明，口腔、食道和BB的结果总体上吻合良好，而胃、小肠、大肠、胸外区域和bb则存在一些差异（例如大肠中差异高达约9倍）。差异主要是由于这些器官在逼真的网格型体模和简化的理想化模型之间存在解剖学差异。网格型ICRP参考体模中的新消化道和呼吸道模型保留了体素型ICRP体模的拓扑结构和尺寸，并且比ICRP以前出版物中采用的简化模型提供了更可靠的SAF值。
