Marino Carmelo, Villaggi Elena, Maggi Giulia, Esposito Marco, Strigari Lidia, Bonanno Elisa, Borzì Giusi R, Carbonini Claudia, Consorti Rita, Fedele David, Fiandra Christian, Ielo Isidora, Malatesta Tiziana, Malisan Maria Rosa, Martinotti Anna, Moretti Renzo, Nardiello Barbara, Oliviero Caterina, Clemente Stefania, Mancosu Pietro
Humanitas C.C.O., Catania, Italy.
Strahlenther Onkol. 2015 Jul;191(7):573-81. doi: 10.1007/s00066-015-0822-6. Epub 2015 Mar 8.
The Italian Association of Medical Physics (AIFM) started a working group dedicated to stereotactic body radiotherapy (SBRT) treatment. In this work, we performed a multicenter planning study on patients who were candidates for SBRT in the treatment of prostate cancer with the aim of evaluating the dosimetric consistency among the different hospitals.
Fourteen centers were provided the contours of 5 patients. Plans were performed following the dose prescription and constraints for organs at risk (OARs) of a reference paper. The dose prescription was 35 Gy in five fractions for the planning target volume (PTV). Different techniques were used (3D-CRT, fixed-Field IMRT, VMAT, CyberKnife). Plans were compared in terms of dose-volume histogram (DVH) parameters. Furthermore, the median DVH was calculated and one patient was re-planned.
A total of 70 plans were compared. The maximum dose to the body was 107.9 ± 4.5 % (range 101.5-116.3 %). Dose at 98 % (D98 %) and mean dose to the clinical target volume (CTV) were 102.0 ± 0.9 % (global range 101.1-102.9 %) and 105.1 ± 0.6 % (range 98.6-124.6 %). Similar trends were found for D95 % and mean dose to the PTV. Important differences were found in terms of the homogeneity index. Doses to OARs were heterogeneous. The subgroups with the same treatment planning system showed differences comparable to the differences of the whole group. In the re-optimized plans, DVH differences among institutes were reduced and OAR sparing improved.
Important dosimetric differences with possible clinical implications, in particular related to OARs, were found. Replanning allowed a reduction in the OAR dose and decreased standard deviations. Multicenter clinical trials on SBRT should require a preplanning study to standardize the optimization procedure.
意大利医学物理协会（AIFM）成立了一个致力于立体定向体部放射治疗（SBRT）治疗的工作组。在这项工作中，我们对前列腺癌SBRT治疗候选患者进行了一项多中心计划研究，目的是评估不同医院之间的剂量学一致性。
为14个中心提供了5名患者的轮廓。根据一篇参考文献中针对危及器官（OAR）的剂量处方和限制条件制定计划。计划靶体积（PTV）的剂量处方为35 Gy，分5次照射。使用了不同的技术（3D-CRT、固定野IMRT、VMAT、射波刀）。根据剂量体积直方图（DVH）参数对计划进行比较。此外，计算了中位DVH，并对一名患者重新制定了计划。
共比较了70个计划。身体的最大剂量为107.9±4.5%（范围101.5 - 116.3%）。临床靶体积（CTV）的98%剂量（D98%）和平均剂量分别为102.0±0.9%（总体范围101.1 - 102.9%）和105.1±0.6%（范围98.6 - 124.6%）。D95%和PTV平均剂量也发现了类似趋势。在均匀性指数方面发现了重要差异。OAR的剂量是不均匀的。采用相同治疗计划系统的亚组显示出与整个组的差异相当的差异。在重新优化的计划中，各机构之间的DVH差异减小，对OAR的保护得到改善。
发现了具有可能临床意义的重要剂量学差异，特别是与OAR相关的差异。重新计划可降低OAR剂量并减小标准差。SBRT的多中心临床试验应要求进行预计划研究以规范优化程序。
