Princess Margaret Hospital, City University of Hong Kong.
J Appl Clin Med Phys. 2013 Nov 4;14(6):4382. doi: 10.1120/jacmp.v14i6.4382.
A new version of progressive resolution optimizer (PRO) with an option of air cavity correction has been implemented for RapidArc volumetric-modulated arc therapy (RA). The purpose of this study was to compare the performance of this new PRO with the use of air cavity correction option (PRO10_air) against the one without the use of the air cavity correction option (PRO10_no-air) for RapidArc planning in targets with low-density media of different sizes and complexities. The performance of PRO10_no-air and PRO10_air was initially compared using single-arc plans created for four different simple heterogeneous phantoms with virtual targets and organs at risk. Multiple-arc planning of 12 real patients having nasopharyngeal carcinomas (NPC) and ten patients having non-small cell lung cancer (NSCLC) were then performed using the above two options for further comparison. Dose calculations were performed using both the Acuros XB (AXB) algorithm with the dose to medium option and the analytical anisotropic algorithm (AAA). The effect of using intermediate dose option after the first optimization cycle in PRO10_air and PRO10_no-air was also investigated and compared. Plans were evaluated and compared using target dose coverage, critical organ sparing, conformity index, and dose homogeneity index. For NSCLC cases or cases for which large volumes of low-density media were present in or adjacent to the target volume, the use of the air cavity correction option in PRO10 was shown to be beneficial. For NPC cases or cases for which small volumes of both low- and high-density media existed in the target volume, the use of air cavity correction in PRO10 did not improve the plan quality. Based on the AXB dose calculation results, the use of PRO10_air could produce up to 18% less coverage to the bony structures of the planning target volumes for NPC cases. When the intermediate dose option in PRO10 was used, there was negligible difference observed in plan quality between optimizations with and without using the air cavity correction option.
一种具有空气空腔校正选项的新型渐进分辨率优化器 (PRO) 已被应用于 RapidArc 容积调强弧形治疗 (RA)。本研究的目的是比较新 PRO 与空气空腔校正选项 (PRO10_air) 的使用情况与不使用空气空腔校正选项 (PRO10_no-air) 的性能，以用于不同大小和复杂性的低密度介质靶区的 RapidArc 计划。首先使用虚拟靶区和危及器官的四个不同简单异质体模的单弧计划对 PRO10_no-air 和 PRO10_air 的性能进行了比较。然后，使用上述两种方案对 12 例患有鼻咽癌 (NPC) 的真实患者和 10 例患有非小细胞肺癌 (NSCLC) 的患者进行了多弧计划，以便进一步比较。剂量计算使用 Acuros XB (AXB) 算法与介质剂量选项和分析各向异性算法 (AAA)。还研究并比较了在 PRO10_air 和 PRO10_no-air 中第一次优化循环后使用中间剂量选项的效果。通过靶区剂量覆盖、关键器官保护、适形指数和剂量均匀性指数对计划进行评估和比较。对于 NSCLC 病例或靶区内部或附近存在大量低密度介质的病例，PRO10 中的空气空腔校正选项的使用是有益的。对于 NPC 病例或靶区中存在小体积的低密度和高密度介质的病例，PRO10 中的空气空腔校正并不能改善计划质量。基于 AXB 剂量计算结果，使用 PRO10_air 可能会导致 NPC 病例的计划靶区骨性结构的覆盖度降低 18%。当在 PRO10 中使用中间剂量选项时，使用和不使用空气空腔校正选项的优化之间观察到计划质量几乎没有差异。
