Division of Cancer Sciences, University of Manchester, M13 9PL, Manchester, UK.
The Christie NHS Foundation Trust, M20 4BX, Manchester, UK.
Sci Rep. 2019 Dec 11;9(1):18820. doi: 10.1038/s41598-019-55349-7.
A new technique for range verification in proton beam therapy has been developed. It is based on the detection of the prompt γ rays that are emitted naturally during the delivery of the treatment. A spectrometer comprising 16 LaBr(Ce) detectors in a symmetrical configuration is employed to record the prompt γ rays emitted along the proton path. An algorithm has been developed that takes as inputs the LaBr(Ce) detector signals and reconstructs the maximum γ-ray intensity peak position, in full 3 dimensions. For a spectrometer radius of 8 cm, which could accommodate a paediatric head and neck case, the prompt γ-ray origin can be determined from the width of the detected peak with a σ of 4.17 mm for a 180 MeV proton beam impinging a water phantom. For spectrometer radii of 15 and 25 cm to accommodate larger volumes this value increases to 5.65 and 6.36 mm. For a 8 cm radius, with a 5 and 10 mm undershoot, the σ is 4.31 and 5.47 mm. These uncertainties are comparable to the range uncertainties incorporated in treatment planning. This work represents the first step towards a new accurate, real-time, 3D range verification device for spot-scanning proton beam therapy.
一种用于质子束治疗中的射程验证的新技术已经被开发出来。它基于在治疗过程中自然发射的瞬发γ射线的检测。采用由 16 个 LaBr(Ce)探测器组成的对称配置的谱仪来记录沿着质子路径发射的瞬发γ射线。已经开发出一种算法，该算法将 LaBr(Ce)探测器信号作为输入，并在全 3 维空间中重建最大γ射线强度峰值位置。对于半径为 8cm 的谱仪，可以容纳儿科头颈部病例，通过检测到的峰的宽度可以确定瞬发γ射线的起源，对于 180MeV 的质子束撞击水模，σ值为 4.17mm。对于半径为 15 和 25cm 的谱仪，以容纳更大的体积，该值增加到 5.65 和 6.36mm。对于半径为 8cm，有 5 和 10mm 的下切，σ值分别为 4.31 和 5.47mm。这些不确定性与治疗计划中包含的射程不确定性相当。这项工作代表了朝着用于点扫描质子束治疗的新的准确、实时、3D 射程验证设备迈出的第一步。
