Purpose To validate that DMPO model for "one step" algorithm can reduce the total MLC segments number, we compare the dosage distribution of "one-step" algorithm with "two-step" algorithm for generating IMRT MLC segments. Methods On the platform of "Pinnacle 8.0h" version radiation treatment planning system developed by Philips , we respectively select one head and neck tumor case, one thorax tumor case and one abdomen tumor case, by means of designing seven fields IMRT planning, then utilized "one-step " algorithm and "two-step" algorithm to optimize and generate IMRT MLC segments, and then calculated dosage distribution, evaluated dosage distribution lines and DVH diagram, in order to compare the two MLC segment groups generated by the two different algorithm. Result For the three IMRT plans selected by us the number of MLC segments generated by "two-step" algorithm appear to be larger than "one-step" algorithm but dosage distribution seems to be worse than the latter. Dissusion For utilizing the "Pinnacle" plan system to design IMRT plan, "one-step" algorithm with "DMPO" definitely can effectively reduce the number of MLC segments, what's more, the result of dosage distribution seems to be better.%目的 通过对比调强子野生成算法的"两步法"与"一步法"所达到的最终剂量分布结果,以验证"一步法"的DMPO 模块能够在达到同等剂量分布的前提条件下有效地减少调强计划的子野生成数.方法 在Philips 公司"Pinnacle 8.0 "版本的放疗计划系统平台上,分别选取头颈部肿瘤、胸部肿瘤与腹部肿瘤的放疗病人各一例,通过设计7野的标准调强放疗计划,分别用"两步法"跟"一步法"优化生成最终的调强子野,并进行剂量分布计算,然后对剂量分布线和剂量体积直方图(DVH 图) 进行分析评估,以及比较两种算法所生成的子野数量.结果 所选取三例肿瘤调强计划中,用"两步法"生成的调强子野数比"一步法"的多,且总体上看前者剂量分布不如后者的好.结论在用于调强放疗计划设计的Pinnacle 计划系统中,通过"一步法"使用DMPO 模块确实能够有效地减少调强子野的生成数量,且会使最终的剂量分布结果更趋于理想化.
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