Commissioning of a 142.4 MeV ultra-high dose rate (UHDR) proton beamline in a synchrotron-based proton therapy system

IF 3.2 2区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Medical physics Pub Date : 2025-07-15 DOI:10.1002/mp.18008

Lingshu Yin, Daniel Sforza, Devin Miles, Umezawa Masumi, Kan Ota, Xun Jia, Heng Li

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Abstract

Background

Recent studies suggest that radiotherapy at ultrahigh dose rates (>40 Gy/s, FLASH) offers normal tissue sparing effects while maintaining tumor control. There is significant interest in preclinical studies investigating the mechanism of FLASH sparing effects.

Purpose

This study aims to commission a fixed proton beamline within a synchrotron-based proton therapy system for preclinical proton FLASH research.

Methods

Modifications were made to the Hitachi PROBEAT-CR synchrotron system to enhance RF extraction power and increase proton beam current at 142.4 MeV. A high-speed electrometer and an optimized transmission ion chamber (IC) were implemented for ultra-high dose rate (UHDR) beam monitoring and delivery, replacing the conventional beam monitoring IC. Beam output was measured using a Faraday cup in both UHDR and clinical modes. Gafchromic film measurements and Monte Carlo simulations were employed to validate dose delivery in a solid water phantom with various spot scanning patterns.

Results

The calibration of transmission IC against Faraday cup shows sufficient charge collection efficiency at both clinical dose rates and UHDR. The UHDR PBS beamline demonstrates better than 1% reproducibility and linearity in the absolute beam output. Due to the limited charge per spill, the delivered dose per spill is inversely proportional to the field size. However, the system can deliver up to 41.4 Gy (268.1 Gy/sec) at 2 cm depth with a field size (FWHM) of 8.2 mm, demonstrating suitability for small animal proton FLASH irradiation studies.

Conclusion

We successfully commissioned a fixed beam proton UHDR PBS beamline in a synchrotron-based proton therapy system. Despite synchrotron-specific system constraints, our system enables controlled UHDR delivery for preclinical proton FLASH research.

Abstract Image

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同步加速器质子治疗系统中142.4 MeV超高剂量率（UHDR）质子束线的调试

最近的研究表明，超高剂量率（40 Gy/s， FLASH）放射治疗在维持肿瘤控制的同时可提供正常组织保留效果。在临床前研究中，对FLASH保护作用的机制有很大的兴趣。目的：在同步加速器质子治疗系统中建立固定质子束线，用于临床前质子FLASH研究。方法对日立PROBEAT-CR同步加速器系统进行改进，提高射频提取功率，提高142.4 MeV的质子束电流。高速静电计和优化的传输离子室（IC）用于超高剂量率（UHDR）光束监测和输送，取代传统的光束监测IC。在UHDR和临床模式下，使用法拉第杯测量光束输出。采用变色膜测量和蒙特卡罗模拟验证了不同点扫描模式的固体水幻影中的剂量传递。结果在临床剂量率和UHDR下，透射IC对法拉第杯的校准均显示出足够的电荷收集效率。UHDR PBS光束线在绝对光束输出中具有优于1%的再现性和线性度。由于每次泄漏的电荷有限，每次泄漏的剂量与场大小成反比。然而，该系统可以在2cm深度以8.2 mm的场尺寸（FWHM）输送高达41.4 Gy (268.1 Gy/sec)，证明适用于小动物质子FLASH照射研究。结论在同步加速器质子治疗系统中成功地建立了固定束流质子UHDR PBS束流线。尽管有同步加速器特定系统的限制，我们的系统可以控制UHDR交付用于临床前质子FLASH研究。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Medical physics 医学-核医学

CiteScore

6.80

自引率

15.80%

发文量

660

审稿时长

1.7 months

期刊介绍： Medical Physics publishes original, high impact physics, imaging science, and engineering research that advances patient diagnosis and therapy through contributions in 1) Basic science developments with high potential for clinical translation 2) Clinical applications of cutting edge engineering and physics innovations 3) Broadly applicable and innovative clinical physics developments Medical Physics is a journal of global scope and reach. By publishing in Medical Physics your research will reach an international, multidisciplinary audience including practicing medical physicists as well as physics- and engineering based translational scientists. We work closely with authors of promising articles to improve their quality.