本研究旨在确定子束宽度对鼻咽癌(NPC)动态调强放射治疗(IMRT)的影响,并确定最有效的放射治疗计划的最佳参数。
本研究评估了20例NPC患者的动态IMRT。仅改变优化参数中的小束宽度(设置为2、4、6、8和10mm,分别命名为BL02、BL04、BL06、BL08和BL10)以优化五组计划的结果。使用计划质量评分系统,对计划靶体积(PTV)和危险器官(OAR)的剂量结果进行客观全面的分析。质量分数越低,计划的质量越好。使用监控单元(MU)和计划交付时间(PDT)评估计划执行的效率和准确性。
BL04mm组的目标和OAR的质量得分最低(0.087),而BL10mm组总分最高(1.249)。BL04mm组具有最高的MU(837MU)和最长的PDT(358s)。然而,每个小组计划的MU范围低于100MU,并且PDT范围在30s内。在BL02、BL04、BL06、BL08和BL10计划中,<5个MU段占33%,16%,24%,33%,占总细分市场的40%,分别,其中最低的是BL04mm组。
较小的细光束宽度不仅减少了OAR剂量,同时保持了PTV的高剂量覆盖率,但也会导致更多的MU,从而产生更大的PDT。考虑到动态IMRT的质量和效率,摩纳哥治疗计划系统的细光束宽度值设置为4mm将是NPC的最佳选择。
This study aimed to identify the effects of beamlet width on dynamic intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC) and determine the optimal parameters for the most effective radiotherapy plan.
This study evaluated 20 patients with NPC were selected for dynamic IMRT. Only the beamlet width in the optimization parameters was changed (set to 2, 4, 6, 8, and 10 mm that were named BL02, BL04, BL06, BL08, and BL10, respectively) to optimize the results of the five groups of plans. Using the plan quality scoring system, the dose results of the planning target volumes (PTVs) and organs at risks (OARs) were analyzed objectively and comprehensively. The lower the quality score, the better the quality of the plan. The efficiency and accuracy of plan execution were evaluated using monitor units (MUs) and plan delivery time (PDT).
The BL04 mm group had the lowest quality score for the targets and OARs (0.087), while the BL10 mm group had the highest total score (1.249). The BL04 mm group had the highest MUs (837 MUs) and longest PDT (358 s). However, the MUs range of each group plan was below 100 MUs, and the PDT range was within 30 s. In the BL02, BL04, BL06, BL08, and BL10 plans, <5 MUs segments accounted for 33%, 16%, 24%, 33%, and 40% of total segments, respectively, with which the lowest was in the BL04 mm group.
Smaller beamlet widths have not only reduced OARs dose while maintaining high dose coverage to the PTVs, but also lead to more MUs that would produce greater PDT. Considering the quality and efficiency of dynamic IMRT, the beamlet width value of the Monaco treatment planning system set to 4 mm would be optimal for NPC.