Delft University of Technology, Radiation Detection and Medical Imaging, Mekelweg 15, 2629 JB Delft, The Netherlands.
Phys Med Biol. 2012 Aug 7;57(15):4885-903. doi: 10.1088/0031-9155/57/15/4885. Epub 2012 Jul 13.
In the design and application of scintillation detectors based on silicon photomultipliers (SiPMs), e.g. in positron emission tomography imaging, it is important to understand and quantify the non-proportionality of the SiPM response due to saturation, crosstalk and dark counts. A new type of SiPM, the so-called digital silicon photomultiplier (dSiPM), has recently been introduced. Here, we develop a model of the probability distribution of the number of fired microcells, i.e. the number of counted scintillation photons, in response to a given amount of energy deposited in a scintillator optically coupled to a dSiPM. Based on physical and functional principles, the model elucidates the statistical behavior of dSiPMs. The model takes into account the photon detection efficiency of the detector; the light yield, excess variance and time profile of the scintillator; and the crosstalk probability, dark count rate, integration time and the number of microcells of the dSiPM. Furthermore, relations for the expectation value and the variance of the number of fired cells are deduced. These relations are applied in the experimental validation of the model using a dSiPM coupled to a LSO:Ce,Ca scintillator. Finally, we propose an accurate method for the correction of energy spectra measured with dSiPM-based scintillation detectors.
在基于硅光电倍增管（SiPM）的闪烁探测器的设计和应用中，例如正电子发射断层成像，理解和量化 SiPM 响应的非比例性（由于饱和、串扰和暗计数引起的）非常重要。最近引入了一种新型的 SiPM，即所谓的数字硅光电倍增管（dSiPM）。在这里，我们开发了一种模型，用于描述在与 dSiPM 光学耦合的闪烁体中沉积给定能量时，响应的微单元（即计数的闪烁光子数）的数量的概率分布。该模型基于物理和功能原理，阐明了 dSiPM 的统计行为。该模型考虑了探测器的光子探测效率；闪烁体的光产额、过剩方差和时间分布；以及 dSiPM 的串扰概率、暗计数率、积分时间和微单元数量。此外，还推导出了被触发的微单元数量的期望值和方差的关系式。这些关系式应用于使用与 LSO：Ce、Ca 闪烁体耦合的 dSiPM 进行的模型实验验证。最后，我们提出了一种用于校正基于 dSiPM 的闪烁探测器测量的能谱的精确方法。
