DIRECT RECONSTRUCTION OF SINGLE-PHOTON EMISSION COMPUTED-TOMOGRAPHY IMAGES USING RETAINED MATRIX-ELEMENTS

In clinical applications, two methods of single-photon emission comput ed tomography (SPECT) reconstruction are widely used. These are filter ed backprojection and iterative reconstruction; Filtered backprojectio n is fast and produces acceptable images. Iterative. reconstruction is slow, but produces images of greater accuracy than backprojcction. Th e authors sought to develop a method of SPECT reconstruction that woul d have the advantages of both established methods: close in speed to b ackprojection and with the accuracy of iterative reconstruction. This was accomplished by computing a direct solution to the set of linear e quations governing SPECT reconstruction. We tested this method of SPEC T reconstruction using a set of projections from a cold rod and sphere phantom. Direct reconstruction produced images having equivalent reso lution to backprojected images, but with double the contrast ratio. Th e direct method required 10 seconds of computation per slice on a Maci ntosh Quadra 950 (Apple Computer; Cupertin, CA), significantly faster than most iterative methods. Copyright (C) 1997 by W.B. Saunders Compa ny.