^(60)Co单板源堆码辐照剂量不均匀度分析

To verify quality of irradiated products by a 3.9PBq single plate (1m×1m) source, Ag2Cr2O7 dosimeters were used for measuring extreme doses in three kinds of Chinese medicine in a actual irradiation area of 1.4m×1.4m facing the source. The product cartons were piled on the irradiation area, and their positions were exchanged to improve dosimetry uniformity of the products. The dosimeters for monitoring the minimum dose were placed in center of the cartons. The minimum doses of the three kinds of Chinese medicine products were 2.98, 1.03 and 1.37kGy respectively, and the maximum doses were 4.61, 2.00 and 2.24kGy, respectively. The dosimetry uni- formities were 1.55, 1.94 and 1.64, respectively, which are within the quality control requirement of U≤2.

X(γ)射线全身照射过程中患者全身剂量分布的蒙特卡罗模拟

目的对比实际测量结果探究利用蒙特卡罗方法模拟患者在实际X(γ)射线全身照射过程中全身剂量分布的可行性。方法利用MCNPX构建准确的医科达Synergy加速器6MV治疗头蒙卡模型,根据CT值与物质密度的关系将ATOM物理体模的CT转换为用于MCNPX计算的体素模型,模拟患者在X(γ)射线全身照射过程中常用的水平照射方式中全身的剂量分布,并将模拟结果与热释光剂量计在ATOM物理体模内不同位置处的测量值进行对比分析其差异。结果标准源皮距下6MV加速器治疗头模型在水模体中计算的百分深度剂量曲线和离轴剂量曲线与医院的实际测量值差异性均<2%,其中10cm×10cm射野下的最大剂量点深度约为1.5cm,与实际测量值相符。全身照射中体模内不同位置处剂量的模拟结果与热释光剂量计测量值的最大差异性约为4%,MCNPX的模拟结果与热释光的测量结果基本符合。结论MCNPX较精确地模拟计算患者全身照射的剂量分布,蒙特卡罗模拟为全身照射过程中患者全身剂量的均匀性优化提供了可能。