Abstract
Positron emission tomography (PET) is an important tool for molecular imaging. Fully three-dimensional (3D) acquisition mode can achieve, high sensitivity of coincidence events, but the absence of inter-slice septa, inevitably leads to increased scattered events. Scatter coincidence add a background to the true coincidence distribution, decreasing contrast by misplacing events during reconstruction and degrades the accuracy of quantitative analysis. Most commercial PET systems employ the single scatter simulation (SSS) algorithm for scatter correction. However, the SSS method achieves limited accuracy because it estimates scatter from single scatter events and does not consider the scatter from out of field of view (OFOV). We have developed a reliable scatter correction scheme for PET/CT imaging with beam stopper device (BS), with the aim of accurately estimating scatter distribution from the projection image. In this research, we proposed an accurate scatter correction method employing the beam stopper device. By directly estimating the scatter component at the LOR corresponding to the stopper, various kinds of scattered events including the most challenging multiple scatter and scatter from outside the FOV can be effectively compensated. Furthermore, no cumbersome iterative process and preliminary 2D estimates of the emitter and attenuator distributions are needed, which could reduce the computation cost and the implementation complexity of the BS method. We conclude that the BS method appears to be a feasible way to correct scattered events in PET/CT imaging.