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.