Zhong Yuncheng, Lu Weiguo, Chen Mingli, Xiong Zhenyu, Cheng Xinyi, Hu Kun, Shao Yiping
Division of Medical Physics and Engineering Department of Radiation Oncology University of Texas Southwestern Medical Center Dallas, Texas 75390 USA.
IEEE Trans Radiat Plasma Med Sci. 2020 Mar;4(2):212-217. doi: 10.1109/trpms.2019.2950231. Epub 2019 Oct 30.
On-line PET image-based method uses an initial particle beam to measure the particle beam range (BR) within the same fraction so that any measured range-shift with respect to the predicted BR can be compensated before the rest therapeutic beam deliveries. However, the method requires to use a low-dose initial beam to minimize the risk of beam overshooting, which leads to low image count and inaccurate BR measurement. In this in-silico study, we evaluated the feasibility of a new on-line PET imaging method that measures BR at the mid-plane of a target volume with part of the high-dose therapy beams to verify BR and guide adaptive treatment re-planning. Simulations included various processes of proton beam radiations to a tumor inside a human brain phantom, positron and PET image generation at the mid-plane with initial beams, activity range measurement, and range-shift compensated beam delivery. The results demonstrated that the new method, under the simulated conditions, can achieve ~1.1 mm mid-plane BR measurement accuracy and closely match the delivered range-shift compensated dose distribution with the planned one. Overall, it is promising that this new method may significantly improve particle therapy accuracy.
基于在线PET图像的方法使用初始粒子束在同一分次内测量粒子束射程（BR），以便在其余治疗束照射之前，能够补偿任何相对于预测BR的测量射程偏移。然而，该方法需要使用低剂量初始束以将束超射的风险降至最低，这导致图像计数低且BR测量不准确。在这项计算机模拟研究中，我们评估了一种新的在线PET成像方法的可行性，该方法使用部分高剂量治疗束在靶区中平面测量BR，以验证BR并指导自适应治疗重新计划。模拟包括质子束对人脑体模内肿瘤的各种辐射过程、用初始束在中平面生成正电子和PET图像、活度范围测量以及射程偏移补偿束照射。结果表明，在模拟条件下，新方法可实现约1.1毫米的中平面BR测量精度，并使递送的射程偏移补偿剂量分布与计划的剂量分布紧密匹配。总体而言，这种新方法有望显著提高粒子治疗的精度。
