Design Study of the Absorber Detector of a Compton Camera for On-Line Control in Ion Beam Therapy
Design Study of the Absorber Detector of a Compton Camera for On-Line Control in Ion Beam Therapy
复制标题
离子束治疗在线控制康普顿相机吸收体探测器的设计研究
DOI：
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发表时间：
2011
影响因子：
1.8
通讯作者：
A. Walenta
中科院分区：
文献类型：
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作者：
M. Richard;M. Dahoumane;D. Dauvergne;M. D. Rydt;G. Dedes;N. Freud;J. Krimmer;J. Létang;X. Lojacono;V. Maxim;G. Montarou;C. Ray;F. Roellinghoff;É. Testa;A. Walenta
本研究的目的是调整康普顿照相机的吸收体探测器的设计，用于离子束治疗期间的即时γ射线成像。通过Geant 4模拟研究了康普顿照相机对具有真实能谱（对应于在碳辐照水模期间发射的瞬发γ射线谱）的光子点源的响应。我们的康普顿相机由一堆2毫米厚的硅条探测器作为散射探测器和闪烁体板作为吸收体探测器。考虑了四种还原剂：LYSO、NaI、LaBr 3和BGO。LYSO和BGO似乎是最合适的材料，因为它们具有高光电横截面，这导致高百分比的完全吸收光子。相互作用的深度测量示出的相机的空间分辨率上有有限的影响。在我们的情况下，在高百分比的光子被完全吸收和低视差误差之间给出最佳折衷的厚度对于LYSO探测器为约4cm，对于BGO探测器为4.5cm。吸收体探测器的宽度对空间分辨率的影响只要小于30cm就不是很明显。
The goal of this study is to tune the design of the absorber detector of a Compton camera for prompt γ-ray imaging during ion beam therapy. The response of the Compton camera to a photon point source with a realistic energy spectrum (corresponding to the prompt γ-ray spectrum emitted during the carbon irradiation of a water phantom) is studied by means of Geant4 simulations. Our Compton camera consists of a stack of 2 mm thick silicon strip detectors as a scatter detector and of a scintillator plate as an absorber detector. Four scintillators are considered: LYSO, NaI, LaBr3 and BGO. LYSO and BGO appear as the most suitable materials, due to their high photo-electric cross-sections, which leads to a high percentage of fully absorbed photons. Depth-of-interaction measurements are shown to have limited influence on the spatial resolution of the camera. In our case, the thickness which gives the best compromise between a high percentage of photons that are fully absorbed and a low parallax error is about 4 cm for the LYSO detector and 4.5 cm for the BGO detector. The influence of the width of the absorber detector on the spatial resolution is not very pronounced as long as it is lower than 30 cm.