Gray Tara, Kolano Anna Maria, Liu Chieh-Wen, Cho Young-Bin, Donaghue Jeremy, Chao Samuel, Suh John, Xia Ping, Farr Jonathan
Cleveland Clinic Foundation, Cleveland, OH, USA.
Applications of Detectors and Accelerators to Medicine (ADAM) SA, Meyrin, Switzerland.
J Radiosurg SBRT. 2024;9(2):145-156.
To compare plan quality among photon volumetric arc therapy (VMAT), Gamma Knife, and three different proton beam modalities.
Fifty-five brain lesions from 20 patients were planned with three different proton spot size ranges of cyclotron-generated proton beams, CPBs (spot size σ: 2.7-7.0 mm), linear accelerator proton beams, LPBs (σ: 2.9-5.5 mm), and linear accelerator proton minibeams, LPMBs (σ: 0.9-3.9 mm), with and without apertures and compared against photon VMAT and Gamma Knife plans. Dose coverage to each lesion for each proton and photon plan was set to 99% of the GTV receiving the prescription (Rx) dose. All proton plans used ±2 mm setup uncertainty and ±2% range uncertainty in robust evaluation to achieve V > 95% of the GTV. Apertures were applied to proton beams irradiating tumors <1 cm volume and located <2.5 cm depth. Conformity index (CI), gradient index (GI), V, V, and mean brain dose were compared across all plan types. The Wilcoxon signed rank test was utilized to determine statistical significance of dosimetric results compared between photon and proton plans.
When compared to CPB generated plans, average CI and GI were significantly better for the LPB and LPMB plans. Aperture-based IMPT plans showed improvement from Gamma Knife for all dosimetric metrics. Aperture-based IMPT plans also showed improvement in all dosimetric metrics for shallow tumors (d < 2.5 cm) when compared with non-aperture-based plans.
The LPB and LPMB stand as excellent alternatives to CPB or photon therapy and significantly increase the preservation of normal tissue.
比较光子容积弧形调强放疗（VMAT）、伽玛刀和三种不同质子束模式的计划质量。
对20例患者的55个脑病变进行计划，采用回旋加速器产生的质子束（CPB，光斑尺寸σ：2.7 - 7.0 mm）、直线加速器质子束（LPB，σ：2.9 - 5.5 mm）和直线加速器质子微束（LPMB，σ：0.9 - 3.9 mm）的三种不同质子光斑尺寸范围，有孔和无孔情况下进行计划，并与光子VMAT和伽玛刀计划进行比较。每个质子和光子计划对每个病变的剂量覆盖设定为接受处方（Rx）剂量的GTV的99%。所有质子计划在稳健评估中使用±2 mm的设置不确定性和±2%的射程不确定性，以实现GTV的V > 95%。对体积<1 cm且深度<2.5 cm的肿瘤，质子束照射时应用孔径。比较所有计划类型的适形指数（CI）、梯度指数（GI）、V、V和平均脑剂量。采用Wilcoxon符号秩检验确定光子和质子计划之间剂量学结果比较的统计学显著性。
与CPB生成的计划相比，LPB和LPMB计划的平均CI和GI显著更好。基于孔径的调强质子治疗（IMPT）计划在所有剂量学指标上均优于伽玛刀。与非基于孔径的计划相比，基于孔径的IMPT计划在浅部肿瘤（d < 2.5 cm）的所有剂量学指标上也有所改善。
LPB和LPMB是CPB或光子治疗的优秀替代方案，可显著提高正常组织的保留率。
