GPU-accelerated exact strip integrals for 2-D iterative reconstruction in emission tomography

The computational efficiency of iterative tomographic reconstruction has been dramatically improved by using GPUs (graphics processing units). However, the use of unmatched projector-backprojector pairs and the approximations for the efficiency of the GPU cause artifacts and errors in reconstruction. For PET or SPECT reconstruction with relatively low resolution, the degradation due to these artifacts and errors becomes more significant as the number of iterations is increased. In this work, we develop a GPU-accelerated method which does not use any approximation for parallelizing the projection and backprojection operations. The method of projection and backprojection we use in this work is based on the area weighted strip integral method which is known as one of the most accurate methods for 2-D reconstruction but has not been considered for acceleration by using the GPU. Our proposed method is guaranteed to retain the reconstruction accuracy by providing a perfectly matched projector-backprojector pair.