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.

中文翻译：

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头侧和尾侧照射几何形状中弯曲姿势的 PIMAL 风格模型的中子器官和有效剂量系数的比较。

人体辐射剂量估计是使用计算参考体模进行的，计算参考体模是人体的解剖学表示。在之前的研究中，剂量重建主要集中在直立姿势的体模上，这限制了在实际工作环境中观察到的姿势的剂量估计的准确性。在这项工作中，国际放射防护委员会 (ICRP) 第 103 号出版物针对成年女性和男性参考体模的单能中子平面源从头顶上方（颅骨）向下引导和从足部下方（尾侧）向上引导的建议用于计算器官吸收和有效剂量系数。使用移动手臂和腿部模型 (PIMAL) 和蒙特卡罗 N 粒子 (MCNP) 辐射传输代码来计算直立、半弯曲 (45°) 和全弯曲的器官吸收剂量和有效剂量系数。弯曲（90°）的幻觉姿势。通过计算系数比率（45°/直立和90°/直立），将针对每个铰接位置计算的剂量与针对直立姿势计算的剂量进行比较。这些比率用于评估直立模型在对铰接位置进行剂量估计和剂量重建时提供可比估计的有效性。这项编译中子颅侧和尾侧姿势特定剂量系数的工作完成了针对单能光子和中子以及颅侧和尾侧单能光子的姿势特定 ICRP 出版物 116 辐照几何形状计算的一系列剂量系数。报告的结果表明，CRA 和 CAU 辐射几何形状中大多数器官的器官吸收剂量系数，弯曲体模明显高于直立体模。由于直立模型低估了器官吸收剂量，这表明了执行剂量计算时姿势的影响。过去中子剂量系数数据中报告的器官剂量被发现忽略了组织中 16O 能量为 0.435、1.0 和 3.21 MeV 的中子共振的影响。报告的数据指出，中子器官吸收剂量被低估高达 60%，特别是在平滑忽略的中子共振能量区域。正在进行的研究正在研究共振对 ICRP 116 几何结构中报告的中子器官吸收剂量系数的影响。