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采用BEAMnrc程序构建医用直线加速器治疗头模型,模拟计算几种单一材料或复合材料构成的均整器对应的射野剂量分布情况.通过对各组射野离轴比(off-axial ratio,OAR)、离轴剂量分布和能量注量分布曲线进行分析并与GB 15213—94国家标准对照,设计具有较好均整度的复合材料均整器.讨论粒子角分布、X射线剂量利用率以及带电粒子污染问题,说明所设计的均整器具有射野内剂量分布平坦、粒子前向性好和带电粒子污染小等优点.
BEAMnrc program was used to construct the medical linear accelerator treatment head model to simulate the corresponding dose distribution of several single materials or composite materials. By analyzing the off-axial ratio (OAR) Off-axis dose distribution and energy fluence distribution curves were analyzed and compared with the national standard GB 15213-94 to design a good uniformity of the composite material homogenizer.The particle angle distribution, X-ray dose utilization and the contamination of charged particles, It shows that the designed homogenizer has such advantages as flat dose distribution in the field, good particle forwardness and small contamination of charged particles.