Data_Sheet_5_A Simple Approach for Experimental Characterization and Validation of Proton Pencil Beam Profiles.PDF

A precise characterization of therapeutic proton pencil beams is essential for the commissioning of any treatment planning system (TPS). The dose profile characterization includes measurement of the beam lateral dose profile in the beam core and far from the beam core, in the so called low-dose envelope, and requires a sophisticated detection system with a few orders of magnitude dynamic range. We propose the use of a single-quantum-sensitive MiniPix Timepix detector, along with an in-house-designed holder to perform measurements of the pencil beam dose profile in air and in water. We validated the manufacturer calibration of the MiniPix Timepix detector in proton beams of various energies and compared the deposited energy spectra to Monte Carlo (MC) simulations. The precision of the lateral dose profile measurements has been systematically validated against Krakow proton facility commissioning data and dose profile simulations performed with MC codes Gate/Geant4 and Fred. We obtained an excellent agreement between MiniPix Timepix measurements and simulations demonstrating the feasibility of the system for a simple characterization and validation of proton pencil beams. The proposed approach can be implemented at any proton therapy facility to acquire experimental data needed to commission and validate analytical and MC-based TPS.

精准表征治疗性质子笔形束，是所有治疗计划系统（Treatment Planning System, TPS）验收调试的必要前提。剂量分布表征需测量射束核心区与远离核心区的侧向剂量分布（即所谓的低剂量包络），且需要具备数个数量级动态范围的高精度探测系统。本研究提出采用单量子敏感型MiniPix Timepix探测器搭配自研支架，开展空气中与水中的质子笔形束剂量分布测量。我们针对不同能量的质子束，对MiniPix Timepix探测器的厂商校准结果进行了验证，并将沉积能谱与蒙特卡洛（Monte Carlo, MC）模拟结果进行了比对。我们以克拉科夫质子治疗装置的验收调试数据，以及采用蒙特卡洛模拟程序Gate/Geant4与Fred开展的剂量分布模拟结果为参照，系统验证了侧向剂量分布测量的精准度。MiniPix Timepix探测器的测量结果与模拟结果吻合度极佳，证实了该系统可用于质子笔形束的简便表征与验证。本研究提出的方案可在任意质子治疗装置中部署，用于获取验收调试与验证解析型及基于蒙特卡洛的治疗计划系统所需的实验数据。