Monte Carlo modeling of a novel depth-encoding PET detector with DETECT2000

Abstract

We designed a depth-encoding positron emission tomography (PET) detector using wavelength shifting (WLS) fibers for a low-cost and high-resolution PET. In order to characterize the theoretical performance of the newly-designed PET detector, we performed a DETECT2000 simulation of the optical photon transport in the crystal array and the WLS fibers. The detector module is made of an array of individual crystals, WLS fibers, and multi-pixel photon counters (MPPCs). The lutetium oxyorthosilicate (LSO) crystal array consists of 15 × 15 crystals with a 2 mm × 2 mm surface size and three different heights: 18, 20, and 22 mm. On every other line, scintillators 2 mm shorter in height are arranged in the y-direction on the top and the x-direction on the bottom of the array to make grooves for insertion of a WLS fiber. The total size of the detector module is 30 mm × 30 mm × 22 mm. One end of each WLS fiber is coupled to MPPCs to measure scintillating light trapped in the fiber. The depth-of-interaction (DOI) resolution and pixel identification capability are determined by using a DETECT2000 simulation. All pixels of the 15 × 15 LSO array are well decoded, and the DOI resolution ranges from 1.43 mm to 2.53 mm with an average of 2.08 mm full width at half maximum (FWHM). These results indicate that the proposed detector performs respectably for high-resolution PET scanning.