Calusi Silvia, Doro Raffaela, Di Cataldo Vanessa, Cipressi Samantha, Francolini Giulio, Bonucci Ivano, Livi Lorenzo, Masi Laura
IFCA Radiotherapy and Medical Physics Unit, Via del Pergolino, 1, 50139 Florence, Italy; AOU Careggi Medical Physics Unit, Largo Brambilla, 3, 50134 Florence, Italy.
IFCA Radiotherapy and Medical Physics Unit, Via del Pergolino, 1, 50139 Florence, Italy.
Phys Med. 2020 Mar;71:31-38. doi: 10.1016/j.ejmp.2020.02.009. Epub 2020 Feb 20.
To assess the performance of a new optimization system, VOLO, for CyberKnife MLC-based SBRT plans in comparison with the existing Sequential optimizer.
MLC-plans were created for 25 SBRT cases (liver, prostate, pancreas and spine) using both VOLO and Sequential. Monitor units (MU), delivery time (DT), PTV coverage, conformity (nCI), dose gradient (R50%) and OAR doses were used for comparison and combined to obtain a mathematical score (MS) of plan quality for each solution. MS strength was validated by changing parameter weights and by a blinded clinical plan evaluation. The optimization times (OT) and the average segment areas (SA) were also compared.
VOLO solutions offered significantly lower mean DT (-19%) and MU (-13%). OT were below 15 min for VOLO, whereas for Sequential, values spanned from 8 to 160 min. SAs were significantly larger for VOLO: on average 10 cm versus 7 cm. VOLO optimized plans achieved a higher MS than Sequential for all tested parameter combinations. PTV coverage and OAR sparing were comparable for both groups of solutions. Although slight differences in R50% and nCI were found, the parameters most affecting MS were MU and DT. VOLO solutions were selected in 80% of cases by both physicians with 88% inter-observer agreement.
The good performance of the VOLO optimization system, together with the large reduction in OT, make it a useful tool to improve the efficiency of CK SBRT planning and delivery. The proposed methodology for comparing different planning solutions can be applied in other contexts.
评估一种新的优化系统VOLO在基于射波刀多叶准直器（MLC）的立体定向体部放疗（SBRT）计划中的性能，并与现有的顺序优化器进行比较。
使用VOLO和顺序优化器为25例SBRT病例（肝脏、前列腺、胰腺和脊柱）创建MLC计划。比较监测单位（MU）、交付时间（DT）、计划靶体积（PTV）覆盖率、适形度（nCI）、剂量梯度（R50%）和危及器官（OAR）剂量，并将其综合以获得每个方案的计划质量数学评分（MS）。通过改变参数权重和进行盲法临床计划评估来验证MS强度。还比较了优化时间（OT）和平均射野面积（SA）。
VOLO方案的平均DT显著降低（-19%），MU显著降低（-13%）。VOLO的OT低于15分钟，而顺序优化器的OT为8至160分钟。VOLO的SA显著更大：平均为10 cm，而顺序优化器为7 cm。对于所有测试的参数组合，VOLO优化的计划比顺序优化器获得更高的MS。两组方案的PTV覆盖率和对OAR的保护相当。尽管在R50%和nCI方面发现了细微差异，但对MS影响最大的参数是MU和DT。两位医生在80%的病例中选择了VOLO方案，观察者间一致性为88%。
VOLO优化系统的良好性能，以及OT的大幅减少，使其成为提高射波刀SBRT计划和实施效率的有用工具。所提出的比较不同计划方案的方法可应用于其他情况。
