Goertzen A L, Zhang X, Liu C-Y, Kozlowski P, Retière F, Ryner L, Sossi V, Stortz G, Thompson C J
Department of Radiology, University of Manitoba, Winnipeg, MB, Canada.
Department of Physics & Astronomy, University of Manitoba, Winnipeg, MB, Canada.
Med Phys. 2012 Jul;39(7Part4):4640. doi: 10.1118/1.4740189.
Silicon photomultiplier (SiPM) detectors are rapidly becoming the detector of choice for research and development of new detectors for positron emission tomography (PET) due to their combination of high gain, fast timing, compact form factor and ability to function in a magnetic field. We are investigating using SiPM based detectors in a compact PET system designed to be inserted into a 7T animal MRI system and enable simultaneous PET/MRI imaging. In order to understand the level of thermal stability required for this PET system, we examined the stability of a prototype SiPM detector vs. temperature. A detector was constructed using a SensL SPMArray4 SiPM array coupled to a LYSO scintillator crystal array. The temperature of the detector was varied between 23 and 60°C in 5°C steps. At each temperature setting data were collected to characterize the detector flood histogram, photopeak amplitude and energy resolution at 511 keV, timing resolution and signal arrival time. While the flood image showed no noticeable changes with temperature, the 511 keV photopeak amplitude showed a linear decrease of 1.5%/°C and the energy resolution degraded by 0.08%/°C. The timing resolution degraded by 1.5 ns, from 3.5 ns to 5 ns when the temperature changed from 23 to 60°C. Over this temperature range there was a shift in the signal arrival time of approximately 3 ns. These results demonstrate that the detector can be operated over a wide range of temperature, giving a large degree of flexibility in choosing an operating temperature set-point for our PET system.
硅光电倍增管（SiPM）探测器正迅速成为正电子发射断层扫描（PET）新探测器研发的首选探测器，因为它具有高增益、快速计时、紧凑的外形尺寸以及在磁场中工作的能力。我们正在研究在一个紧凑型PET系统中使用基于SiPM的探测器，该系统设计用于插入7T动物MRI系统并实现同时进行PET/MRI成像。为了了解该PET系统所需的热稳定性水平，我们研究了一个SiPM探测器原型的稳定性与温度的关系。使用一个与LYSO闪烁体晶体阵列耦合的SensL SPMArray4 SiPM阵列构建了一个探测器。探测器的温度在23至60°C之间以5°C的步长变化。在每个温度设置下收集数据，以表征探测器的泛光直方图、511keV处的光电峰幅度和能量分辨率、计时分辨率以及信号到达时间。虽然泛光图像随温度没有明显变化，但511keV的光电峰幅度以1.5%/°C的线性速率下降，能量分辨率以0.08%/°C的速率退化。当温度从23°C变为60°C时，计时分辨率从3.5ns退化到5ns，退化了1.5ns。在这个温度范围内，信号到达时间有大约3ns的偏移。这些结果表明，该探测器可以在很宽的温度范围内运行，这为我们的PET系统选择工作温度设定点提供了很大的灵活性。
