New approach to obtain high resolution using conventional block designs in PET

High spatial resolution is essential to image small lesions in positron emission tomography. Traditional methods suggest using small crystals to obtain high resolution. In this study, a new method is introduced to achieve high spatial resolution by using scintillators with different decay times arranged in a checkerboard pattern. Pulse shape discrimination was implemented to determine which crystal the gamma energy was deposited. In this work, a 13×13 LSO crystal array and a 13×13 LSO-GSO checkerboard crystal array using 4×4×20 mm³ crystals were built and optimized using light sharing techniques. Similarly, using 2.5×2.5×19 mm³ LSO and LYSO crystals, a 17×17 LSO-LYSO checkerboard crystal array was built as a high-resolution application. The average pixel energy resolution for the 13×13 LSO was measured to be 14.5%. Similarly, the average pixel resolutions for the GSO part of the 13×13 LSO-GSO crystal array and the LSO part of the same array were measured to be 13.9% and 18.5%, respectively. The average crystal energy resolutions for the LSO and LYSO parts of the 17×17 LSO-LYSO crystal array were measured to be 23.5% and 24.2%, respectively. The average peak-to-valley ratios in the position profiles were measured to be 2.1 for the 13×13 LSO crystal array, 7.2 for the LSO part of the 13×13 LSO-GSO crystal array and 4.3 for the GSO part of the 13×13 LSO-GSO crystal array. Similarly, the average peak-to-valley ratios in the position profiles were measured to be 2.5 for the LSO part of the 17×17 LSO-LYSO crystal array and 2.7 for the LYSO part of the 17×17 LSO-LYSO crystal array.