Performance Comparison of DOI-Encoding PET Detectors Based on 1.1-mm Pitch BGO Arrays With Different Reflectors

Bismuth germanate (BGO)-based positron emission tomography (PET) detectors are potential candidates for low-dose imaging PET scanners, owing to the high stopping power and low background radiation of BGO. In this article, we compared the performance of two dual-ended readout PET detectors based on $15\times15$ BGO arrays. Both arrays had the same 1.1 mm pitch but utilized different reflectors—barium sulfate (BaSO4) and enhanced specular reflector film (ESR)—for high-resolution PET applications. The detectors were constructed with Hamamatsu 13361–2050-08 silicon photomultiplier arrays. Each BGO element had dimensions of $1.02\times 1.02\times20$ mm3. The lateral surfaces of the BGO elements were unpolished (saw-cut), while the two ends were polished. Flood histograms showed that the detector based on the BGO array with BaSO4 reflector had much better crystal identification and depth-of-interaction (DOI) resolution. Specifically, the energy, DOI, and timing resolutions for the detector using the BGO array with BaSO4 reflector were 19.8 ± 1.5%, 4.13 ± 0.48 mm, and 2.80 ± 0.23 ns, respectively. In contrast, the values obtained using the BGO array with ESR reflector were 20.9 ± 2.1%, 7.69 ± 1.92 mm, and 2.93 ± 0.20 ns, respectively.