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.
Highlights
Positron emission tomography (PET) has become commercially available with successful applications in oncology, cardiology and neurology [1,2]
In order to help break through the barrier, we have performed extensive experimental studies to assess the coincidence timing resolution (CTR) of positron-emission tomography (PET) detectors constructed with samples of different scintillators from different vendors that were fabricated into different shapes with various surface treatments
The CTR can be improved through the enhancement of the light collection efficiency by optimizing the geometry and surface treatment of the scintillator. This article describes these studies in much greater detail than we previously presented at the IEEE Nuclear Science Symposium and Medical Imaging Conference [30], and analyzes the experimental data in depth and compares the performances of the detectors constructed with various scintillator materials, vendors, shapes, surface treatments and silicon photomultipliers systematically
Summary
Positron emission tomography (PET) has become commercially available with successful applications in oncology, cardiology and neurology [1,2]. There are continuous efforts to improve the spatial resolution, sensitivity and signal-to-noise ratio (SNR) in the reconstructed. PET images since improvements in these characteristics could significantly facilitate the clinical and preclinical applications of PET imaging [7,8,9,10,11,12]. The SNR in conventional PET images are limited by the sensitivity of the scanner. There are two strategies to improve the sensitivity of a PET scanner. The first strategy is to increase the geometric sensitivity of the scanner by increasing its axial extent to achieve total body coverage [13,14,15,16]
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