Phantom Evaluation of Energy-Based Scatter Estimation in an SiPM PET Scanner

PET measurements include a background of scattered radiation which must be estimated as a part of image reconstruction. In this work, an implementation of energy-based scatter (EBS) estimation is described in detail and evaluated in PET/CT phantom studies, including a comparison to standard single-scatter simulation (SSS). The EBS method had no adjustable parameters. An 8-ring Biograph Vision PET/CT system was used. Phantoms provided sinogram regions in which the scatter content was known to be 100%. These were: a cylindrical phantom with a slab insert; a NEMA-94 image quality phantom; a uniform cylinder; and a cardiac phantom. Sinograms were coarsely sampled based on groups of 10×10 crystals. Evaluation criteria included image mean values and image roughness as well as contrast recovery in regions that were completely void of radioactivity. EBS and SSS were comparable. EBS resulted in slightly greater image roughness in one test and better contrast recovery in another test.