Ultra fast TOF 3D reconstruction using SIMD and symmetry superior to GPU implementation

TOF PET 3D reconstruction adds another layer of complexity. Thus it becomes a challenge to find the most efficient method to optimize the reconstruction without compromising image quality. In this study, mCT PET scanner data is used for image reconstruction and comparison. This study shows how an ultrafast forward and back projector pair TOF 3D reconstruction is implemented based on Symmetry SIMD Projector (SSP) algorithm. The Symmetry in the algorithm translates to four symmetric relationships; +90° symmetry of the projection angle, mirror-symmetry on the Radial bin axis, symmetry of the integral direction along LOR, symmetry of the oblique segment angle. The use of SIMD allows the access of four data points by one operand which reduces computation time by a factor of four. Therefore, SSP algorithm can ideally reduce the computation time of forward projection and back projection by a factor of 64. The computer hardware used is off the shelf workstation with Intel Xeon E5540 2×CPU, 12GB, 1×GPU Tesla. The reconstructed image size is 400×400×109 pixels. For the same data set, the SSP algorithm using a CPU based reconstruction was able to achieve twice the timing improvement over the standard GPU counterpart.