Correlation of SPECT images of a three-dimensional brain phantom using a surface fitting technique

The accuracy of a surface fitting technique was investigated for registration of single photon emission tomography (SPECT) brain images. Fiduciary markers were placed on the outside of a three-dimensional brain phantom filled with Tc-99m solution. The phantom and markers were scanned at several orientations in the scanner and contours were produced for the slices of each set. Parameters were fit to rotate and translate images acquired at each orientation to match the images acquired at each of the other orientations. Independent fits based on the measured market positions were done to determine the rotational and translational parameters more precisely. The maximum error measured in the translational parameters was less than 1/2 pixel in any direction and the errors in the angle parameters were all less than 3°, with most less than 1.5°