基于质子束激发热声信号的布拉格峰定位-《中国医学物理学杂志》

文章信息/Info

Author(s):: HE Shiqi; YANG Yan; School of Physics and Technology, Wuhan University, Wuhan 430072, China

Keywords:: Keywords: Bragg peak; proton-excited thermoacoustic signal; travel time inversion; localization

摘要:: 目的：使用质子束激发热声信号对质子束的布拉格峰定位，分析其在质子治疗中应用的可行性。方法：通过Kwave工具包模拟质子束在水中的传播过程，使用放置的传感器接收质子束激发产生的γ波走时数据，再将走时数据进行反演得到布拉格峰位置的修正量，从而完成对布拉格峰定位。结果：在均匀介质中，当初始的布拉格峰位置在目标布拉格峰位置5 cm范围内，使用Kwave模拟得到的走时数据进行定位，无噪声的情况下，定位误差在1.3 mm以内，对其进行加噪处理后，定位误差仍在3 mm以内。使用波前扩展的线性走时插值射线追踪算法得到的走时数据进行反演，能完成零误差定位。结论：使用质子束激发热声信号，仅需要少量的传感器就能对质子束的布拉格峰进行实时定位，走时数据的准确性对定位算法有一定的影响。但是通过加噪实验发现，本算法具有较好的稳定性和收敛性。

Abstract:: Abstract: Objective To locate the Bragg peak of proton beam using proton-excited acoustic signal and analyze its feasibility in proton therapy. Methods Kwave toolkit was used to simulate the propagation process of the proton beam in water, and sensors were placed to receive the travel time data of γ-wave generated by proton excitation. The received travel time data were inverted to obtain the correction of the Bragg peak position, thereby localizing the Bragg peak. Results In the uniform medium, when the initial Bragg peak position was within 5 cm of the target Bragg peak position, the travel time data obtained by Kwave simulation was used for localization. In the case of no noise, the positioning error was within 1.3 mm; and after noise adding, the localization error was still within 3 mm. The precise localization of the Bragg peak was achieved by the inversion of the travel time data obtained by the linear travel time ray tracing algorithm of wavefront expansion. Conclusion When using proton-excited acoustic signals, only a small number of sensors are needed to localize the Bragg peaks of the proton beam. Although the accuracy of the travel time data has a certain effect on the localization algorithm, it is found through the noise-adding experiment that the proposed algorithm has good robustness and convergence.