Overscan reduction in spiral scan long object problem

Recently a number of approaches solving the long object problem with spiral scan appeared in the literature. Unlike the algorithms which employ circular scans for solving the long object problem, with only spiral scan it is necessary to scan regions of the object adjacent to the ROI in order to reconstruct the ROI without contamination; the spiral path required beyond the ROI is referred to as overscan in the literature. Overscan exposes the regions in the long object adjacent to the ROI to radiation as well as incurs additional computation time In this paper we present a number of methods to reduce the undesirable overscan, with emphasis on the local ROI algorithm.