A prototype MR insert PET detector with strip-line readout

We are developing a MR insert PET detector using SiPM for small animal imaging. Our detector design is based on the strip-line signal readout that we have developed to efficiently handle large amount signals for SiPM-based TOF PET. The stripline readout has an advantageous feature suitable for building PET integrated within MR. In strip-line readout, the signal digitization is accomplished remotely from the detection module, thereby the front-end electronics of the detector within MR is minimal; the interference between two systems, e.g., magnetic field distortion due to PET, can be minimized accordingly. The feasibility of the strip-line readout for PET/MR has been demonstrated in our previous study. The current prototype MR insert PET is comprised of 8 detector modules, which are installed in a plastic cylindrical supporting structure. Each detector module consists of 8x4 LYSO arrays (3x3x10 mm
³
each) and two Hamamatsu S13361-3050NE-04 MPPC arrays (4x4, 3.2 mm pitch); 32 SiPM signals are routed in 4 strip-lines so that 8 LYSO/SiPM signals in a row are connected to each strip-line. The signals from strip-lines are fed to a 72-ch multi-voltage threshold (MVT) digitizer, which digitizes the input by TDCs implemented in FPGA. Experiments have been carried out to evaluate the detector performance, and image reconstruction also has been performed for a simple shape object. In the paper, the detail on the development of the MR insert PET are explained, and preliminary test results are presented.