Abstract：
OBJECTIVE: Proton stereotactic radiosurgery (PSRS) has emerged as an innovative proton therapy modality aimed at achieving precise dose delivery with minimal impact on healthy tissues. This study explores the dosimetric outcomes of PSRS in comparison to traditional intensity-modulated proton therapy (IMPT) by focusing on cases with small target volumes. A custom-made aperture system designed for proton therapy, specifically tailored to small target volumes, was developed and implemented for this investigation.
METHODS: A prerequisite mechanical validation through an isocentricity test precedes dosimetric assessments, ensuring the seamless integration of mechanical and dosimetry analyses. Five patients were enrolled in the study, including two with choroid melanoma and three with arteriovenous malformations (AVM). Two treatment plans were meticulously executed for each patient, one utilizing a collimated aperture and the other without. Both plans were subjected to robust optimization, maintaining identical beam arrangements and consistent optimization parameters to account for setup errors of 2 mm and range uncertainties of 3.5%. Plan evaluation metrics encompassing the Heterogeneity Index (HI), Paddick Conformity Index (CIPaddick), Gradient Index (GI), and the R50% index to evaluate alterations in low-dose volume distribution.
RESULTS: The comparative analysis between PSRS and traditional PBS treatment revealed no significant differences in plan outcomes, with both modalities demonstrating comparable target coverage. However, collimated apertures resulted in discernible improvements in dose conformity, dose fall-off, and reduced low-dose volume.
CONCLUSIONS: This study underscores the advantageous impact of the aperture system on proton therapy, particularly in cases involving small target volumes.
METHODS: A prerequisite mechanical validation through an isocentricity test precedes dosimetric assessments, ensuring the seamless integration of mechanical and dosimetry analyses. Five patients were enrolled in the study, including two with choroid melanoma and three with arteriovenous malformations (AVM). Two treatment plans were meticulously executed for each patient, one utilizing a collimated aperture and the other without. Both plans were subjected to robust optimization, maintaining identical beam arrangements and consistent optimization parameters to account for setup errors of 2 mm and range uncertainties of 3.5%. Plan evaluation metrics encompassing the Heterogeneity Index (HI), Paddick Conformity Index (CIPaddick), Gradient Index (GI), and the R50% index to evaluate alterations in low-dose volume distribution.
RESULTS: The comparative analysis between PSRS and traditional PBS treatment revealed no significant differences in plan outcomes, with both modalities demonstrating comparable target coverage. However, collimated apertures resulted in discernible improvements in dose conformity, dose fall-off, and reduced low-dose volume.
CONCLUSIONS: This study underscores the advantageous impact of the aperture system on proton therapy, particularly in cases involving small target volumes.
摘要：
目的：质子立体定向放射外科（PSRS）已成为一种创新的质子治疗方式，旨在实现精确的剂量给药，同时对健康组织的影响最小。本研究通过关注目标体积较小的病例，探讨了PSRS与传统强度调节质子治疗（IMT）相比的剂量学结果。为质子治疗设计的定制孔径系统，专门针对小目标体积，是为这项调查开发和实施的。
方法：在剂量测定评估之前，通过等中心测试进行的先决条件机械验证，确保机械和剂量测定分析的无缝集成。五名患者被纳入研究，包括两个脉络膜黑色素瘤和三个动静脉畸形（AVM）。为每位患者精心执行了两个治疗计划，一个利用准直孔径和其他没有。这两个计划都经过了鲁棒优化，保持相同的光束布置和一致的优化参数，以解决2mm的设置误差和3.5％的范围不确定性。包含异质性指数(HI)的计划评估指标，帕迪克合格指数(CIPaddick)，梯度指数（GI），和R50%指数评估低剂量体积分布的变化。
结果：PSRS和传统PBS治疗之间的比较分析显示计划结果没有显着差异，两种模式都显示出可比的目标覆盖率。然而,准直孔导致剂量一致性的明显改善，剂量下降，减少低剂量体积。
结论：本研究强调了孔径系统对质子治疗的有利影响，特别是在涉及小目标量的情况下。
方法：在剂量测定评估之前，通过等中心测试进行的先决条件机械验证，确保机械和剂量测定分析的无缝集成。五名患者被纳入研究，包括两个脉络膜黑色素瘤和三个动静脉畸形（AVM）。为每位患者精心执行了两个治疗计划，一个利用准直孔径和其他没有。这两个计划都经过了鲁棒优化，保持相同的光束布置和一致的优化参数，以解决2mm的设置误差和3.5％的范围不确定性。包含异质性指数(HI)的计划评估指标，帕迪克合格指数(CIPaddick)，梯度指数（GI），和R50%指数评估低剂量体积分布的变化。
结果：PSRS和传统PBS治疗之间的比较分析显示计划结果没有显着差异，两种模式都显示出可比的目标覆盖率。然而,准直孔导致剂量一致性的明显改善，剂量下降，减少低剂量体积。
结论：本研究强调了孔径系统对质子治疗的有利影响，特别是在涉及小目标量的情况下。
