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目的使用蒙特卡罗算法分析不同照射角度变化对乳腺癌患者术后电子线放疗计划剂量分布影响。方法使用MCNP5蒙特卡罗粒子输运软件包建立乳腺癌患者术后电子线照射模型,模拟电子线照射过程中350°、355°、5°、10°四个照射角度变化,计算靶区胸壁及敏感器官患侧肺、健侧肺、心脏的剂量分布,分析其剂量学特点。结果选取350°、355°、0°、5°、10°五个角度后,0°对照组胸壁接受剂量最高,355°组、350°组、10°组、5°组接受剂量依次降低;敏感器官的接受剂量在旋转角度模拟后均有升高,患侧肺和心脏靠近射野,接受剂量和变化程度均较大,0°对照组、350°组、355°组、10°组、5°组患侧肺接受剂量依次升高,0°对照组、355°组、350°、10°组、5°组组心脏和健侧肺接受剂量依次升高。结论本文使用蒙特卡罗算法对乳腺癌患者术后电子线放疗进行模拟研究,发现不同照射角度变化会降低靶区接受剂量,升高敏感器官接受剂量。
Objective To analyze the effects of different irradiation angles on the planned dose distribution of postoperative electron beam irradiation in patients with breast cancer using Monte Carlo algorithm. Methods The electron beam irradiation model of breast cancer patients was established by using MCNP5 Monte Carlo particle transport software package to simulate the change of four irradiation angles of 350 °, 355 °, 5 ° and 10 ° during the electron beam irradiation. Sensory organs ipsilateral lung, contralateral lung, heart dose distribution, analysis of its dosimetric characteristics. Results After the five angles of 350 °, 355 °, 0 °, 5 ° and 10 ° were selected, the chest wall in 0 ° control group received the highest dose, and the doses in 355 °, 350 °, 10 ° and 5 ° groups decreased in turn. The receiving dose of sensory organs increased after the simulation of rotation angle, and the affected lung and heart were close to the radiation field. The receiving dose and the degree of change were all greater in 0 ° control group, 350 ° group, 355 ° group, 10 ° group, In the 5 ° group, the receiving doses of the affected lungs increased in turn, while those in the 0 ° control group, the 355 ° group, the 350 °, 10 ° group and the 5 ° group increased. Conclusions The Monte Carlo method is used to simulate the postoperative electron beam radiation therapy in breast cancer patients. It is found that the changes of different irradiation angles will decrease the target dose and increase the dose of sensitive organ.