title: A Backprojection-Based Parameter Estimation Technique for Skew-Slit Collimation.
abstract: To estimate geometric parameters in a skew-slit single photon emission computed tomography (SPECT) scan, a simple method is presented that uses a single point source and a backprojection process. The method employs one point source placed sufficiently far from the axis of rotation but in the field of view. A skew-slit geometry is considered where the estimated parameters include the focal lengths of both opaque planes and the location of multiple transaxial slits and a single axial slit. Computer simulations show that view-angle independent parameters can be uniquely estimated. Three experimental scans were performed, and the view-angle independent parameters were accurately estimated. Tilt, sagging, and mechanical shifts result in parameters that change depending on the view angle in the experimental scans. These view-angle dependent parameters were estimated using the single point-source technique, but reconstructed phantom images showed some error in the estimation of the view-angle dependent parameters.
authors.affiliation: Utah Center for Advanced Imaging Research (UCAIR), Department of Radiology, and the Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT 84108 USA ( j.piatt@utah.edu ).
authors.forename: Jacob A
authors.initials: JA
authors.lastname: Piatt
authors.affiliation: Utah Center for Advanced Imaging Research (UCAIR), Department of Radiology, University of Utah, Salt Lake City, UT 84108 USA ( larry@ucair.med.utah.edu ).
authors.forename: Gengsheng L
authors.initials: GL
authors.lastname: Zeng
keywords: Acquisition geometry; SPECT; computed tomography; parameter estimation; pinhole; skew-slit