Toward real-time, volumetric dosimetry for FLASH-capable clinical synchrocyclotrons using protoacoustic imaging

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

Medical physics Pub Date : 2024-07-29 DOI:10.1002/mp.17318

Siqi Wang, Gilberto Gonzalez, Daniel Rocky Owen, Leshan Sun, Yan Liu, Townsend Zwart, Yong Chen, Liangzhong Xiang

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引用次数: 0

Abstract

Background

Radiation delivery with ultra-high dose rate (FLASH) radiotherapy (RT) holds promise for improving treatment outcomes and reducing side effects but poses challenges in radiation delivery accuracy due to its ultra-high dose rates. This necessitates the development of novel imaging and verification technologies tailored to these conditions.

Purpose

Our study explores the effectiveness of proton-induced acoustic imaging (PAI) in tracking the Bragg peak in three dimensions and in real time during FLASH proton irradiations, offering a method for volumetric beam imaging at both conventional and FLASH dose rates.

Methods

We developed a three-dimensional (3D) PAI technique using a 256-element ultrasound detector array for FLASH dose rate proton beams. In the study, we tested protoacoustic signal with a beamline of a FLASH-capable synchrocyclotron, setting the distal 90% of the Bragg peak around 35 mm away from the ultrasound array. This configuration allowed us to assess various total proton radiation doses, maintaining a consistent beam output of 21 pC/pulse. We also explored a spectrum of dose rates, from 15 Gy/s up to a FLASH rate of 48 Gy/s, by administering a set number of pulses. Furthermore, we implemented a three-dot scanning beam approach to observe the distinct movements of individual Bragg peaks using PAI. All these procedures utilized a proton beam energy of 180 MeV to achieve the maximum possible dose rate.

Results

Our findings indicate a strong linear relationship between protoacoustic signal amplitudes and delivered doses (R² = 0.9997), with a consistent fit across different dose rates. The technique successfully provided 3D renderings of Bragg peaks at FLASH rates, validated through absolute Gamma index values.

Conclusions

The protoacoustic system demonstrates effectiveness in 3D visualization and tracking of the Bragg peak during FLASH proton therapy, representing a notable advancement in proton therapy quality assurance. This method promises enhancements in protoacoustic image guidance and real-time dosimetry, paving the way for more accurate and effective treatments in ultra-high dose rate therapy environments.

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利用原声成像技术，为具有 FLASH 功能的临床同步循环加速器实现实时、容积剂量测定。

背景：快速低角度射束超分割放疗（FLASH）有望改善治疗效果并减少副作用，但由于其超高剂量率，在放射剂量的准确性方面存在挑战。目的：我们的研究探索了质子诱导声成像（PAI）在 FLASH 质子照射过程中三维实时跟踪布拉格峰的有效性，为传统和 FLASH 剂量率下的容积束成像提供了一种方法：我们开发了一种三维 PAI 技术，使用 256 元超声探测器阵列，用于 FLASH 剂量率质子束。在这项研究中，我们使用具有 FLASH 功能的同步环形加速器的光束线测试了原声信号，将布拉格峰的远端 90% 设置在距离超声阵列 35 毫米左右的位置。这种配置使我们能够评估各种质子辐射总剂量，并保持 21 pC/脉冲的一致束流输出。我们还通过施用一定数量的脉冲，探索了从 15 Gy/s 到 48 Gy/s 的 FLASH 率的剂量率谱。此外，我们还采用了三点扫描光束方法，利用 PAI 观察各个布拉格峰的明显移动。所有这些过程都使用了 180 MeV 的质子束能量，以达到尽可能高的剂量率：结果：我们的研究结果表明，原声信号振幅与输送剂量之间存在很强的线性关系（R2 = 0.9997），不同剂量率之间的拟合效果一致。该技术成功提供了闪烁率下布拉格峰的三维渲染，并通过伽马指数绝对值进行了验证：原声系统展示了 FLASH 质子治疗过程中布拉格峰三维可视化和跟踪的有效性，代表了质子治疗质量保证的显著进步。这种方法有望增强原声图像引导和实时剂量测定，为在超高剂量率治疗环境中进行更准确、更有效的治疗铺平道路。

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.