Ax-PET: Demonstration of a novel PET concept

PET (Positron Emission Tomography) detector development is a very active field, which takes strong advantage of concepts and technologies originally developed in the high energy physics domain. The AX-PET project proposes a novel geometrical approach for high resolution and high sensitivity PET imaging, in which long scintillator crystals (LYSO) are placed axially in the tomograph. Arrays of WLS strips, placed behind each layer of crystals, provide the measurement of the axial coordinate. Both the crystals and the WLS strips are individually read out by G-APDs (Geiger-mode Avalanche Photo Diodes).
Two AX-PET modules were built at CERN and fully characterized with point-like Na-22 sources, demonstrating competitive performance in terms of spatial and energy resolutions. Operated in coincidence, the two modules form the demonstrator for an axial PET scanner, which has been successfully used for the reconstruction of images of several phantoms filled with F-18 in aqueous solution.
Since recently, digital Silicon Photomultipliers (dSiPM) from Philips are being investigated as alternative photodetectors for the AX-PET. With their highly integrated read-out electronics and excellent intrinsic time resolution, dSiPM’s may allow for compact detector modules with Time of Flight capability (TOF-PET).
The AX-PET detector concept, its performance, the reconstructed images of different phantoms, as well as the very first results achieved with the dSiPM, will be reported.