Evaluation of Various Scintillator Materials in Radiation Detector Design for Positron Emission Tomography (PET)

Abstract

The performance of radiation detectors used in positron-emission tomography (PET) is determined by the intrinsic properties of the scintillators, the geometry and surface treatment of the scintillator crystals and the electrical and optical characteristics of the photosensors. Experimental studies were performed to assess the timing resolution and energy resolution of detectors constructed with samples of different scintillator materials (LaBr3, CeBr3, LFS, LSO, LYSO: Ce, Ca and GAGG) that were fabricated into different shapes with various surface treatments. The saturation correction of SiPMs was applied for tested detectors based on a Tracepro simulation. Overall, we tested 28 pairs of different forms of scintillators to determine the one with the best CTR and light output. Two common high-performance silicon photomultipliers (SiPMs) provided by SensL (J-series, 6 mm) or AdvanSiD (NUV, 6 mm) were used for photodetectors. The PET detector constructed with 6 mm CeBr3 cubes achieved the best CTR with a FWHM of 74 ps. The 4 mm co-doped LYSO: Ce, Ca pyramid crystals achieved 88.1 ps FWHM CTR. The 2 mm, 4 mm and 6 mm 0.2% Ce, 0.1% Ca co-doped LYSO cubes achieved 95.6 ps, 106 ps and 129 ps FWHM CTR, respectively. The scintillator crystals with unpolished surfaces had better timing than those with polished surfaces. The timing resolution was also improved by using certain geometric factors, such as a pyramid shape, to improve light transportation in the scintillator crystals.

Optical Simulation and Experimental Assessment with Time–Walk Correction of TOF–PET Detectors with Multi-Ended Readouts

“…A 22 Na point source with an activity of 0.74 MBq was located between the reference detector and the test detector. According to previous research [ 36 ], the bias voltage of the SiPMs was set to 37.5 V to obtain better timing performance. All experiments were carried out in a light, tight box.…”

Development and Evaluation of a Dual-Layer-Offset PET Detector Constructed with Different Reflectors

“…A high-performance test system with good timing resolution was used in this study [6]. The time resolutions of the three dual-layer-offset arrays with different reflectors were tested and the results are shown in Figure 12.…”

“…Image reconstruction techniques can then be used to obtain the distribution of radiotracers. Single-crystal scintillators, such as lutetium-yttrium oxyorthosilicate (LYSO), bismuth germanate (BGO), and gadolinium aluminum gallium garnet (GAGG) have been studied and found to be advantageous over other materials for PET applications [6]. LYSO is widely used in state-of-the-art PET and PET detectors for its high light yield and short decay time.…”

The Core of Medical Imaging: State of the Art and Perspectives on the Detectors

“…Coincidence timing resolution (CTR) is an important index for evaluating the efficiency of detectors for a PET system: the main objective in the design and construction of efficient detectors for PET tomographs is to reduce the CTR as much as possible. This also allows the additional timeof-flight (TOF) information to be incorporated into the PET image reconstruction [135,136] increasing the image SNR and effective sensitivity. Among the various scintillators, LSO, LYSO, MLS, GSO: Ce, Zr, LGSO, LaCI3, LaBr3, BGO, CWO [137,138] are the most used.…”