Analysis of Data Corrections for the First-Generation Radiofrequency-Penetrable PET Insert for Simultaneous PET/MR

This work focused on studying key data corrections which include annulus-based normalization, attenuation correction using an annulus transmission scan, and variance reduction of random coincidence events for the first-generation radiofrequency-penetrable PET insert for simultaneous PET/MR. The brain dedicated PET system is composed of 16 detector modules. Each module employs an array of 3.2 x 3.2 x 20 mm3 LYSO crystal elements which are 1-1 coupled to arrays of silicon photomultipliers (SiPM). Front-end electronics multiplex the output of 128 pixels to 16 vertical-cavity surface-emitting lasers (VCSEL). The VSCELs generate unique optical output patterns per pixel which are passed via fiber optics to an external DAQ. To achieve RF-penetrability of the body coil RF excitation signal and maintain MRI compatibility, the modules in the assembled system are electrically isolated from the MRI and spaced with 1 mm gaps for the RF fields to enter. Variance reduction was performed on random coincidence data experimentally acquired from a Hoffman phantom whereas the annulus-based normalization and annulus attenuation correction was performed on a cylinder to assess non-uniformity. The reconstruction of the non-normalized cylinder showed a non-uniformity of 54.24%, annulus normalization reduced the non-uniformity to 9.34%, and the addition of attenuation correction yielded 8.63%.