论文标题
验证质子闪光放射疗法综合优化基础的量子物理过程
Validation of the Quantum Physics Processes Underlying the Integrated Optimization of Proton FLASH Radiotherapy
论文作者
论文摘要
Flash是一种新的治疗方式，需要优化剂量，剂量率和LET。在这里，我们在闪光条件下验证了这三个数量，其中包括时间依赖性瞬时剂量率（IDR）曲线中的量子不确定性，并让新提出的新提出的集成优化框架的光谱。 剂量，IDR和LET的测量是在Emory Proton Therapy Center上使用标称能量为250 MEV和3D印刷脊过滤器的闪光灯质子束进行的。由于3D打印树脂是由专有化学公式制成的，因此我们开发了一种现实表征和建模材料中的材料的方法。使用2D Matrixx PT检测器以及新型的4D多层带电离室（MLSIC）测量了3D空间中的绝对剂量，该剂量也同时测量IDR。通过使用Minipix timePix3检测迅速伽马仪，在次级束中测量了进一步的计时数据；第二个检测器Advapix TimePix3用于测量LET。为了说明粒子传输的量子机械性质，我们开发了一种用于检测高通量初级光束内各个质子的技术，这对于正确测量让光谱是必不可少的。 TOPAS模拟同意测量，绝对剂量通常的伽马及率至少为95％（标准为3 mm/3％）。同样，IDR和LET表现出良好的一致性，平均IDR值在0.3％以内与10％的波动一致，并且让分布至少重叠至少85％，并且显示出高的组件（大于4 keV/UM）的高度增加，而深度的增加。 随着LET和FLASH优化的流行，测量IDR，LET和剂量将变得更加重要，我们希望此处描述的方法将被证明是放疗治疗计划和QA中的有用工具。
FLASH is a new treatment modality that requires optimization of dose, dose rate, and LET. Here we validate these three quantities under FLASH conditions, which includes the quantum uncertainty in the time-dependent instantaneous dose rate (IDR) curves and LET spectra that underlie the newly proposed integrated optimization framework. Measurements of dose, IDR, and LET were performed at the Emory Proton Therapy Center using a FLASH proton beam with a nominal energy of 250 MeV and a 3D printed ridge filter. Because 3D printing resin is made from a proprietary chemical formula, we developed a method for realistically characterizing and modeling the material in simulations. Absolute dose in 3D space was measured using a 2D MatriXX PT detector as well as by a novel 4D multi-layer strip ionization chamber (MLSIC), which also simultaneously measures IDR. Further timing data was measured in the secondary beam by detecting prompt gammas using a Minipix Timepix3; a second detector, Advapix Timepix3, was used to measure LET. To account for the quantum mechanical nature of particle transport, we developed a technique for detecting individual protons within a high flux primary beam, which was necessary for properly measuring LET spectra. TOPAS simulations agreed with measurement, with absolute dose typically having a gamma passing rate of at least 95% (3 mm/3% criteria). Likewise, IDR and LET showed good agreement, with averaged IDR values agreeing within 0.3% with fluctuations on the order of 10%, and LET distributions overlapping by at least 85% and showing an increase in high LET components (greater than 4 keV/um) with increasing depth. As LET and FLASH optimization continues to grow in popularity, measuring IDR, LET, and dose will become even more important, and we expect that the methods described here will prove to be useful tools in radiotherapy treatment planning and QA.
