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目的 :评价静态调强放疗治疗肺癌等运动幅度较大肿瘤的可行性。方法 :应用自行研制的运动体模系统模拟呼吸运动 ,测量不同运动幅度及不同运动方向对基于多叶光栅的静态调强放疗射束半影、剂量分布及绝对剂量的影响。结果 :靶区运动明显增加了射野在运动方向的半影 ,导致了低剂量区面积增大及高剂量区不确定性的增加 ,但70 %～ 90 %的等剂量线变化不显著。虽然不同情况下各测量点的剂量有不同程度的变化 ,但若将运动等不确定性因素考虑在内 ,多次测量后总体变化幅度均在允许的范围之内。结论 :靶区运动加宽了射束的半影 ,但在适当补偿运动等影响靶区确定的因素后 ,应用静态调强放疗治疗周期性运动的肿瘤是可行的
Objective: To evaluate the feasibility of static intensity modulated radiotherapy in the treatment of lung cancer and other large-scale tumors. Methods: The self-developed motion phantom system was used to simulate respiratory motion. The effects of different amplitude and directions of motion on the penumbra, dose distribution and absolute dose of MMT beam based on multi-leaf gratings were measured. Results: The movement of the target area significantly increased the penumbra of the field in the direction of motion, resulting in an increase of the area of the low dose area and the increase of the uncertainty of the high dose area. However, the isodose lines of 70% to 90% did not change significantly. Although the dose of each measuring point varies with different degrees in different situations, if the uncertainties such as exercise are taken into account, the overall changes after multiple measurements are within the allowable range. CONCLUSIONS: The movement of the target area broadens the penumbra of the beam. However, it is feasible to apply static intensity modulated radiotherapy to periodically mottled tumors after proper compensation of the factors affecting the target area