Simulation study on the diverging SPECT system with a semiconductor detector

Single photon emission CT (SPECT) systems with a semiconductor detector have several advantages compared with conventional SPECT systems with a NaI(Tl) scintillation detector in terms of energy resolution and spatial resolution. On the other hand, one of the disadvantages of the detector is a small field-of-view (FOV), and thus we proposed a new SPECT system with a diverging collimator to enlarge the FOV. In this SPECT system with the diverging collimator, the effect of the shadow zone and a truncation problem in the axial direction should be considered. And to cope with this problem, we adopted an FBP-type cone-beam reconstruction algorithm with Radon space interpolation, which was proposed by Yang et al. This method reconstructs more accurate images than the Feldkamp, Davis, Kress (FDK) method or Grangeat's method. In this study we evaluated the images reconstructed with Yang's method applied to the data acquired with a diverging collimator. The results obtained with simulations showed the feasibility of the SPECT system with a semiconductor detector and a diverging collimator.