Patent ID: 8315428

Claim:
A method for measuring a single photon emission computed tomography collimator's hole orientations, comprising: (a) providing a plurality of parallel spaced apart line radiation sources at a distance from a detector, the detector having a field of view; (b) positioning a first collimator between the plurality of spaced apart line radiation sources and the detector; (c) obtaining a set of line images of the plurality of line radiation sources by scanning/stepping the plurality of line radiation sources across the first collimator in a first direction; (d) obtaining a second set of line images of the plurality of line radiation sources by scanning/stepping the plurality of line radiation sources across the first collimator in a second direction that is orthogonal to the first direction; (e) repeating the steps (c) and (d) for a second collimator, wherein one of the two collimators is a reference collimator and the other of the two collimators is a collimator being measured, whereby the line images obtained using the reference collimator are reference collimator line images and the line images obtained using the collimator being measured are measured collimator line images, wherein the line images are stored in a machine-readable storage medium accessible to a processor unit; (f) said processor unit analyzing the reference collimator line images and the measured collimator line images and determining the offset distances dx, dy for each pair of lines between the reference collimator line images and the measured collimator line images; and (g) said processor unit calculating hole orientation angles θx, θy for each collimator hole in the collimator being measured, wherein the reference collimator line images and the measured collimator line images comprise line profile data representing radiation intensities detected by the detector and the step (f) comprising: (h) identifying and labeling all peaks in the line profile data of the reference collimator line images and the measured collimator line images, based on each peak's position relative to a center of the field of view of the detector; (i) calculating peak statistics for each peak; (j) determining whether each peak is a valid peak that satisfies a predetermined condition based on the peak statistics and the position of each peak; (k) re-labeling each valid peak based on the position of the valid peak relative to the center of the field of view of the detector; and (l) pairing the valid peaks from the line profile data of the reference collimator line images with the corresponding valid peaks from the line profile data of the measured collimator line images according to the re-labeled position of the valid peaks.