【摘要】 通过蒙特卡罗方法模拟瓦里安IX加速器6 MV能量档、10 cm×10 cm射野下的剂量分布,研究电子线参数对剂量分布的影响,并寻找确定最优电子线参数的简化方法。结果表明:当电子线平均能量和径向强度分布分别在5.5~6.4 Me V及0.1~0.4 cm变化时,百分深度剂量没有显著变化;当径向强度分布在0~0.19 cm变化时,主剂量区内模拟与测量的离轴剂量差异很小,但在半影区,二者之间有较大差异;通过调整平均角展宽,可以使不同深度处模拟与测量的离轴剂量有更好的符合度。根据本文提出的电子线参数确定方法可以使模拟的剂量更为精确,由于百分深度剂量与离轴剂量分别对径向强度分布及平均能量不敏感,各参数可以独立地根据单一剂量分布确定。更多还原

【Abstract】 [Background] With the development of radiation technology, it needs to improve the accuracy of dose simulation. [Purpose] Build up a simplified benchmarking procedure to determine the incident electron beam parameters independently using a Monte Carlo linear accelerator model. [Methods] A 10 cm×10 cm field is simulated to acquire the parameters influence on the dose distributions for Varian IX 6 MV megavoltage electron beams. [Results] The calculated depth doses had no significant changes when the electron mean energy and radial intensity varied in 5.5~6.4 Me V and 0.1~0.4 cm respectively. And the dose profile simulated with an electron radial intensity in 0~0.19 cm had a good agreement with the measured dose profile in the main field while obvious discrepancies in the penumbra region. The mean angular spread was found to be 0.3° to get good matching between calculations and measurements at all considered depths. [Conclusion] Accurate dose distributions are achieved by using the incident electron beam parameters benchmarked with the proposed procedure. As the percentage depth doses and dose profiles are insensitive to the electron energy and radial intensity correspondingly, they are feasible to benchmark individually.更多还原