A Depth-Encoding Detector Module for an MR-Compatible PET Insert

Yibao Wu¹, Yongfeng Yang¹, Bo J. Peng¹, Simon R. Cherry¹

The next generation of MR-compatible PET insert is under development for small-animal imaging providing greater than an order of magnitude increase in sensitivity by utilizing 20 mm thick scintillator crystal elements with excellent stopping power. A detector module based on avalanche photodiode read out with depth-of-interaction encoding was designed and evaluated to overcome the resolution-degrading parallax errors associated with such thick detectors. Detectors for the new PET insert were characterized in terms of crystal identification and energy spectra. Data were acquired outside a 7T MR scanner, inside the MR scanner, with and without sequences running. An MR phantom also was measured with the PET detector module inside the MR system. No significant interference between the PET detector module and the MR system were observed. The design of the new PET insert based on these detectors is presented.