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[目的]研究加速器不同机架角时多叶准直器叶片重力对放疗剂量的影响。[方法]用MapCheck二维半导体矩阵进行测量,预选静态调强和动态调强中大小合适的单方向治疗野和机架角,保证精确摆位和测量相应平面剂量,用MapCheck剂量分析系统的γ(3mm,3%)分析方法对相应通过率进行定量分析。[结果]当加速器机头为0°时,不同机架角静态调强与机架角为0°时静态调强平均通过率相差2%以内,动态调强与机架角为0°时平均通过率相差更大,但误差都在5%以内,但当加速器机头为90°时不同机架角时静态调强和动态调强与机架角为0°时的平均通过率都比较相近,这时多叶准直器叶片重力对放疗剂量的影响最小。[结论]当加速器机头为0°时不同机架角多叶准直器叶片重力对放疗剂量确实有影响,但当机头为90°时不同机架角多叶准直器叶片重力对放疗影响大大减少。为了减少多叶准直器叶片重力对放疗剂量的影响也应对多叶准直器叶片做定期的维护和保养。
[Objective] The research aimed to study the influence of the multi-leaf collimator blade’s gravity on the radiation dose when the accelerator’s different gantry angle. [Method] With MapCheck two-dimensional semiconductor matrix, pre-selected unidirectional therapeutic fields and gantry angles in static state and dynamic state were preselected to ensure accurate placement and measurement of the corresponding planar dose. The γ (3mm, 3%) analysis of the corresponding pass rate quantitative analysis. [Result] When the head of the accelerator was 0 °, the average rate of static IMRs at different rack angles was within 2% of the static IMRs at 0 ° rack angles, and the average between dynamic IMRs and rack angles was 0 ° But the error is less than 5%. However, when the head of the accelerator is 90 °, the average passing rate at different rack angles is similar to the static pass rate and the dynamic pass rate when the rack angle is 0 ° , When the multi-leaf collimator leaves the smallest dose of radiation on the impact of gravity. [Conclusion] The leaf weight of multi-leaf collimator with different frame angles did affect the dose of radiation when the head of the accelerator was 0 °. However, when the head was 90 °, The impact is greatly reduced. In order to reduce the influence of multi-leaf collimator blade gravity on radiotherapy dose, multi-leaf collimator blade should also be regularly maintained and maintained.