γ辐照加工用新型工作模体设计研究

本文研究设计了一种用于获取γ辐照装置辐射场和货物剂量场真实分布的新型工作模体。基于真实γ辐照装置参数构建了有效可用的模拟辐射场，提出了新型工作模体的结构和填料设计方法。采用蒙特卡罗方法和随机填充方法（RCS）模拟计算剂量计套管材料与壁厚、填料小球尺寸、空心填料小球尺寸与壁厚、小球填充方式等影响模体剂量学性能的主要因素的分布规律。在满足计算置信度的前提下，参数优化取值范围为：套管采用壁厚为3~5 mm的铝管，对辐射场干扰不超过4.372 23%；填料选择外径为1~4 cm、壁厚为1.1~11.5 mm、材料等效性好、货物密度模拟范围为0.1~0.5 g/cm³的聚丙烯小球，对辐射场干扰不超过9.998 44%；均匀填充和随机填充模式对辐射场干扰基本持平，且均不超过10%。结果表明，当前设计可行有效，投入低、兼顾参数多且量程更宽，适合推广应用。

Study on Design Method of New Operating Phantom for Gamma Irradiation Processing

A new operating phantom was studied for obtaining the true distribution of the radiation field of the gamma irradiation facility and the dose field in the cargo container. An effective and usable simulated radiation field was constructed based on the parameter of the real gamma irradiation facility. The design method for the structure and padding of new operating phantom was proposed. The Monte Carlo method and random filling method (RCS) were adopted to simulate the distribution law of the main factor affecting the dosimetry parameters of the phantom body, such as the dosimeter sleeve material and wall thickness, filler ball size, hollow filler ball size and wall thickness, ball filling method, etc. Under the premise of satisfying the calculation confidence level, the optimization ranges of parameters are as follows: Aluminum tube with wall thickness of 3-5 mm is used as the sleeve, which interferes with the radiation field no more than 4.372 23%; Polypropylene sphere with outer diameter of 1-4 cm, wall thickness of 1.1-11.5 mm, cargo density simulating range of 0.1-0.5 g/cm³, and good material equivalence is selected as the phantom padding, which interferes with the radiation field no more than 9.998 44%; The interference level of the uniform and random filling modes on the radiation field is almost the same, and both are less than 10%. The results show that the current design is feasible and effective, with low investment, more parameters and wider range, and it is suitable for popularization and application.