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 x 15 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 x 1.02 x 20 mm(3). 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.