Performance test of a LSO-APD PET module in a 9.4 Tesla magnet

One of the future goals is to install a PET detector in a magnetic field for a combined PET/MRT device. Thus, in this study the influence of a 9.4 Tesla magnetic field on a small scintillation detector with avalanche photodiode (APD) readout was tested. The detector, comprising a 3.7/spl times/3.7/spl times/12.0 mm/sup 3/ lutetium oxyorthosilicate (LSO) crystal coupled to the 3 mm O active surface of an APD was exposed to 511 keV gamma rays from a /sup 22/Na source. The energy resolution at room temperature was 14.4% (FWHM). Measurements of gain and energy resolution were performed outside and in the center of a homogeneous magnetic field of 9.4 Tesla. Both, the gain and energy resolution were unaffected by the magnetic field being either parallel or orthogonal to the electrical field of the APD. These results prove the potential of using APDs in a combined PET/MRT imaging system.