Modified simultaneous algebraic reconstruction technique and its parallelization in cryo-electron tomography

Three-dimensional reconstruction of cryo-electron tomography (cryo-ET) has emerged as the leading technique in analyzing structures of complex pleomorphic cellulars. A classical iterative method, simultaneous algebraic reconstruction technique (SART), has been employed to reconstruct volume images in cryo-ET. However, SART starts with an arbitrary approximation and takes into account only a weighted factor when updating density value in every error-correction iterative procedure, thus limits the improvement of the reconstruction resolution. Facing these problems, we present a modified simultaneous algebraic reconstruction technique (MSART) which applies several key techniques, a back projection technique (BPT) and an adaptive adjustment of corrections. Experimental results show that MSART can improve significantly the quality of reconstruction. Additionally, in order to address the computational requirements demanded by the reconstruction of large volumes, we have presented and implanted a strategy to parallel the MSART algorithm on DAWNING 4000H cluster system, and obtained a good computational performance.