The physical range uncertainty limits the exploitation of the full potential of charged particle therapy. In this work, we face this issue aiming to measure the absolute Bragg peak position in the target. We investigate p, 4He, 12C and 16O beams accelerated at the Heidelberg Ion-Beam Therapy Center. The residual range of the primary 12C ions is correlated to the energy spectrum of the prompt gamma radiation. The prompt gamma spectroscopy method was demonstrated for proton beams accelerated by cyclotrons and is developed here for the first time for heavier ions accelerated by a synchrotron. We develop a detector system that includes (i) a spectroscopic unit based on cerium(III) bromide and bismuth germanium oxide scintillating crystals, (ii) a beam trigger based on an array of scintillating fibers and (iii) a data acquisition system based on a FlashADC. We test the system in two different scenarios. In the first series of experiments, we detect and identify 19 independent spectral lines over a wide gamma energy spectrum in the presence of the four ion species for different targets, including a water target with a titanium insert. In the second series of experiments, we introduce a collimator aiming to relate the spectral information to the range of the primary particles. We perform extensive measurements for a 12C beam and demonstrate submillimetric precision for the measurement of its Bragg peak position in the experimental setup. The features of the energy and time spectra for gamma radiation induced by p, 4He and 16O are investigated upstream and downstream from the Bragg peak position. We conclude the analysis by extrapolating the required future developments, which would be needed to achieve range verification with a 2 mm accuracy during a single fraction delivery of [Formula: see text] physical dose.

中文翻译：

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瞬发伽马光谱仪用于基于同步加速器的设施中的12C离子绝对范围验证。

物理范围的不确定性限制了带电粒子疗法的全部潜力的开发。在这项工作中，我们面临着旨在测量目标中绝对布拉格峰位置的问题。我们研究了在海德堡离子束治疗中心加速的p，4He，12C和16O束。初级12C离子的残留范围与即时伽马射线的能谱相关。瞬变伽马能谱法已被证明可用于回旋加速器加速的质子束，并且是首次针对同步加速器加速的重离子而开发的方法。我们开发了一种探测器系统，该系统包括（i）基于溴化铈（III）和氧化锗铋闪烁晶体的光谱单元，（ii）基于闪烁光纤阵列的光束触发器，以及（iii）基于FlashADC的数据采集系统。我们在两种不同的情况下测试系统。在第一个系列实验中，我们在存在四个离子物种的情况下，针对不同目标（包括带有钛插入物的水目标），在宽伽马能谱上检测并识别出19条独立的谱线。在第二系列实验中，我们引入准直仪，旨在将光谱信息与初级粒子的范围相关联。我们对12C光束进行了广泛的测量，并证明了在实验设置中测量其布拉格峰位置的亚微米级精度。p引起的伽马射线能量和时间谱的特征 在布拉格峰位置的上游和下游对4He和16O进行了研究。我们通过推断所需的未来发展来结束分析，这是在单次递送[公式：参见正文]物理剂量期间实现2毫米精度的范围验证所必需的。