Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430023 China.
Department of Radiation Oncology, Beaumont Health System, Royal Oak, Michigan.
Int J Radiat Oncol Biol Phys. 2023 Nov 1;117(3):730-737. doi: 10.1016/j.ijrobp.2023.05.012. Epub 2023 May 16.
To take full advantage of FLASH dose rate (40 Gy/s) and high-dose conformity, we introduce a novel optimization and delivery technique, the spot-scanning proton arc therapy (SPArc) + FLASH (SPLASH).
SPLASH framework was implemented in an open-source proton planning platform (MatRad, Department of Medical Physics in Radiation Oncology, German Cancer Research Center). It optimizes with the clinical dose-volume constraint based on dose distribution and the dose-average dose rate by minimizing the monitor unit constraint on spot weight and accelerator beam current sequentially, enabling the first dynamic arc therapy with voxel-based FLASH dose rate. This new optimization framework minimizes the overall cost function value combined with plan quality and voxel-based dose-rate constraints. Three representative cases (brain, liver, and prostate cancer) were used for testing purposes. Dose-volume histogram, dose-rate-volume histogram, and dose-rate map were compared among intensity modulated proton radiation therapy (IMPT), SPArc, and SPLASH.
SPLASH/SPArc could offer superior plan quality over IMPT in terms of dose conformity. The dose-rate-volume histogram results indicated SPLASH could significantly improve V Gy/s in the target and region of interest for all tested cases compared with SPArc and IMPT. The optimal beam current per spot is simultaneously generated, which is within the existing proton machine specifications in the research version (<200 nA).
SPLASH offers the first voxel-based ultradose-rate and high-dose conformity treatment using proton beam therapy. Such a technique has the potential to fit the needs of a broad range of disease sites and simplify clinical workflow without applying a patient-specific ridge filter, which has never before been demonstrated.
为了充分利用 FLASH 剂量率（40 Gy/s）和高剂量适形性，我们引入了一种新的优化和递送技术，即点扫描质子弧治疗（SPArc）+FLASH（SPLASH）。
SPLASH 框架在开源质子计划平台（MatRad，德国癌症研究中心放射肿瘤学医学物理系）中实现。它根据剂量分布和剂量平均剂量率的临床剂量-体积约束进行优化，通过最小化点权重和加速器束流的监视器单位约束来优化，从而实现基于体素的 FLASH 剂量率的第一个动态弧形治疗。这种新的优化框架通过结合计划质量和基于体素的剂量率约束来最小化整体成本函数值。使用三个有代表性的病例（脑、肝和前列腺癌）进行测试。比较了强度调制质子放射治疗（IMPT）、SPArc 和 SPLASH 的剂量-体积直方图、剂量率-体积直方图和剂量率图。
SPLASH/SPArc 可以在剂量适形性方面提供优于 IMPT 的计划质量。剂量率-体积直方图的结果表明，与 SPArc 和 IMPT 相比，SPLASH 可以显著提高所有测试病例的靶区和感兴趣区的 V Gy/s。同时生成了最优的每个点的束流，这在研究版本中的现有质子机规格范围内（<200 nA）。
SPLASH 提供了使用质子束治疗的第一个基于体素的超高剂量率和高剂量适形性治疗。这种技术有可能满足广泛的疾病部位的需求，并简化临床工作流程，而无需应用患者特定的脊滤波器，这是以前从未展示过的。
