Abstract
Fully 3D positron emission tomography (PET) can achieve higher system sensitivity of coincidence events, but the absence of inter-slice septa inevitably leads to increased scattered events. The scattered events can contribute as much as 50% of the total detected events. In this study, we proposed a scatter correction method for 3D PET based on a beam stopper device. The stoppers were placed surrounding the object to attenuate primary beams. The scatter and scatter fraction were directly estimated at those blocked lines of response and then interpolated to other radial bins using cubic splice interpolation (beam stopper method, BS) or the dual-energy window information (beam-stopper scatter fraction method, BS-SF), respectively. The performance was evaluated by using Monte Carlo simulations of several digital phantoms. For the abdomen phantom study conducted by the BS method, the estimated scatter distribution matched well with the true one. For the Utah phantom study, the proposed BS-SF method can accurately estimate the scatter fraction distribution and improve image contrast and quantification without noticeable noise increase. The simulated results also demonstrated a better restoration of image contrast for the non-homogeneous Zubal phantom. We conclude that the proposed scatter correction method could effectively suppress various kinds of scattered events, including single scatter, multiple scatter, and scatter from outside the field-of-view. It is a direct, fast, and accurate technique for scatter correction in 3D PET.