Evaluation of a compact, high-resolution SPECT detector based on digital silicon photomultipliers

Abstract

MicroSPECT is one of the main functional imaging techniques used in the preclinical setting. Even though high-resolution images can be obtained with currently available systems, their sensitivity is often quite low due to the use of multi-pinhole collimation. This results in long acquisition times and hampers dynamic imaging. However, it has already been shown that this limited sensitivity can be overcome using high-resolution detectors. In this article, we therefore investigated the use of a digital photon counter (DPC) in combination with a 2 mm thick monolithic LYSO crystal for SPECT imaging. These light sensors contain arrays of avalanche photodiodes whose signals are directly digitised. The DPCs have the advantage that they are very compact, have a high intrinsic resolution, are MR compatible and allow disabling cells with a high dark count rate. In order to investigate the influence of the temperature dependent dark count rate on the detector performance, we compared it at 3 °C and 18 °C. At 3 °C, we observed an energy resolution of 28.8% and an intrinsic spatial resolution of 0.48 mm. Furthermore, the count rate at 10% loss is 60 kcps. Next, we looked at the event loss at 18 °C caused by the higher dark count rate and found a 5% loss compared to the 3 °C measurements. At this higher temperature the energy resolution becomes 29.2% and the intrinsic spatial resolution decreases to 0.52 mm. Due to the 5% count loss, the count rate at 10% loss increases to 63 kcps. A small degradation of the detector performance is thus observed at 18 °C.These results show the usefulness of this detector for SPECT imaging together with its excellent intrinsic spatial resolution. A drawback of the detector is its low, spatially varying energy resolution. Even though the detection efficiency and intrinsic spatial resolution are better at 3 °C, results are still acceptable at 18 °C.

Design, Performance Evaluation, and Modeling of an Ultrahigh Resolution Detector Dedicated for Simultaneous SPECT/MRI

“…8) with much less computing cost. The spatial resolving power is significantly improved compared to other MRI compatible CZT/CdTe detectors, such as GMI-CZT [33], and scintillator detectors [59] shown in Table. 2.…”

Collimator design for a multipinhole brain SPECT insert for MRI

“…The detector modules have shown to be MR-compatible 7 and have an excellent intrinsic resolution (0.5 mm) and an energy resolution of 20% (at 140 keV) when combined with a monolithic 2 mm thick LYSO crystal. 26 Excellent spatial resolution makes it possible F. 1.…”

“…In this study, we design a SPECT insert for MRI based on a multipinhole collimator and dSiPM detector modules, which have shown to be MR-compatible 7 and have an excellent intrinsic resolution (0.5 mm) and an energy resolution of 20% (at 140 keV) when combined with a monolithic 2 mm thick LYSO crystal. 26 An excellent detector resolution makes it possible to design a multipinhole system with minification, 27 as opposed to traditional multipinhole systems, which use magnification to obtain a good spatial resolution by placing the detector relatively far from the pinholes (phs) [see Eq. (1)].…”

Large-Area SiPM Pixels (LASiPs): a cost-effective solution towards compact large SPECT cameras

“…A few thousand channels would be needed to fill a 50 × 40 cm 2 camera using SiPMs, dramatically increasing the cost and complexity of the system. This is one of the reasons why up to now almost all research in SiPMs for SPECT has been limited to small cameras [12,13,14]. Larger SiPMs are normally not built because their capacitance increases significantly with size.…”