PurposeProton 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.MethodsA 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.ResultsThe 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.ConclusionsThis study underscores the advantageous impact of the aperture system on proton therapy, particularly in cases involving small target volumes.

中文翻译：

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利用准直孔径和质子笔束扫描 (PBS) 进行立体定向放射治疗

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输送，同时对健康组织的影响最小。本研究通过重点关注小靶体积的病例，探讨了 PSRS 与传统调强质子治疗 (IMPT) 的剂量学结果。为此研究开发并实施了专为质子治疗设计的定制孔径系统，专门针对小目标体积。方法在剂量测定评估之前，通过等中心测试进行必要的机械验证，确保机械和剂量测定分析的无缝集成。 5 名患者参与了这项研究，其中 2 名患有脉络膜黑色素瘤，3 名患有动静脉畸形 (AVM)。我们为每位患者精心执行了两种治疗计划，一种使用准直光圈，另一种则不使用。两个计划都经过了稳健的优化，保持相同的光束布置和一致的优化参数，以解决 2 毫米的设置误差和 3.5% 的范围不确定性。计划评估指标包括异质性指数 (HI)、帕迪克一致性指数 (CI)帕迪克）、梯度指数（GI）和 R50% 指数来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，两种方式都显示出可比较的目标覆盖范围。然而，准直孔径在剂量一致性、剂量下降和减少低剂量体积方面带来了明显的改善。结论这项研究强调了孔径系统对质子治疗的有利影响，特别是在涉及小靶体积的情况下。