System characteristics of simulated limited angle TOF PET

We quantified the changes in sensitivity and scatter fraction between different configurations by GATE Monte Carlo simulations. A full ring system with either 60 or 120 rings of LaBr3 crystals was modeled. A limited angle system with the same number of detectors as the 60 ring system was constructed by only using half of the ring and doubling the axial extent. A line source was used as a representative source for the volume sensitivity. The semi-ring (two opposed curved detectors) with the same amount of detectors as a full ring system has 98% more sensitivity. Point sensitivity is almost the same. Scatter fraction is also equal between both systems. Contrast noise studies show the reduction of contrast by the limited angle information. The increased sensitivity, however, improves the background noise for a limited angle system. The reduction of contrast can be avoided by rotating the limited angle system.