METHODS: Thirty patients\' cervical cancer VMAT plans were designed with a Pinnacle TPS (Philips) and divided equally into two groups: the simple group (SG, target volume was only the PTV) and the complex group (CG, target volume included the PTV and PGTV). The plans from the Pinnacle TPS were transferred to the Monaco TPS (Elekta). The plans\' parameters all remained unchanged, and the dose was recalculated. Gamma passing rates (GPRs) obtained from dose distribution from Pinnacle TPS compared with that from Monaco TPS with SNC software based on three triaxial planes (transverse, sagittal and coronal). GPRs and DVH were used to quantify the difference between the CCC algorithm in pinnacle TPS and the MC algorithm in Monaco TPS.
RESULTS: Among the statistical dose indexes in DVHs from the Pinnacle and Monaco TPSs, there were 7(7/15) dose indexes difference with statistically significant differences in the SG, and 10(10/18) dose indexes difference with statistically significant differences in the CG. With 3%/3 mm criterion, the most (5/6) GPRs were greater than 95% from the SG and CG. But with 2%/2 mm criterion, the most (5/6) GPRs were less than 90% from the two groups. In addition, we found that GPRs were also related to the selected triaxial planes and the complexity of the plan (GPRs varied with the SG and CG).
CONCLUSIONS: Obvious difference between the CCC and MC algorithms from Pinnacle and Monaco TPS. DVH maybe better than 2D gamma analysis on quantifying difference of the CCC and MC algorithms. Some attention should be paid to the uncertainty of the TPS algorithm, especially when the indicator on the DVH is at the critical point of the threshold value, because the algorithm used may overestimate or underestimate the DVH indicator.
方法:30例宫颈癌VMAT计划采用PinnacleTPS(Philips)设计,并平均分为两组:简单组(SG,目标体积仅为PTV)和复杂组(CG,目标音量包括PTV和PGTV)。PinnacleTPS的计划已转移到摩纳哥TPS(Elekta)。计划参数都保持不变,重新计算了剂量。从PinnacleTPS的剂量分布获得的Gamma通过率(GPR)与使用基于三个三轴平面的SNC软件从摩纳哥TPS获得的剂量分布(横向,矢状和冠状)。GPR和DVH用于量化pinnacleTPS中的CCC算法与摩纳哥TPS中的MC算法之间的差异。
结果:在Pinnacle和MonacoTPS的DVH的统计剂量指数中,有7个(7/15)剂量指标差异有统计学意义,和10(10/18)个剂量指数差异具有统计学意义。3%/3毫米标准,最多(5/6)来自SG和CG的GPR大于95%。但以2%/2毫米标准,两组中最多(5/6)的GPR低于90%。此外,我们发现GPR也与选定的三轴平面和计划的复杂性有关(GPR随SG和CG而变化)。
结论:Pinnacle和摩纳哥TPS的CCC和MC算法之间存在明显差异。在量化CCC和MC算法的差异上,DVH可能优于2D伽马分析。应该注意TPS算法的不确定性,特别是当DVH上的指示器处于阈值的临界点时,因为使用的算法可能会高估或低估DVH指标。