Backprojection-based imaging geometric parameter estimation.

In SPECT (single photon emission computed tomography) and X-ray CT, point sources are commonly used to acquire data for imaging parameter estimation. The parameters are estimated by fitting the point source projection data to a mathematical model of the imaging system. This paper introduces two backprojection-based parameter estimation methods. In the first method a point source is attached to the object; the second method is data-based without using a point source at all.