Tomographic gamma cameras
GT-1 Tomographic spatial resolution
This test characterizes the spatial resolution in tomographic reconstruction. Using the reconstructed study of a point source obtained through filtered backprojection, the FWHM is calculated in each direction (X, Y, Z) by fitting a Gaussian function to the count profile obtained after integrating the counts in the direction perpendicular to the one for which the FWHM is being calculated.
GT-2 Center of rotation
The determination of the center of rotation involves quantifying deviations in the rotational axis of the gamma camera's detector head. The detector head of tomographic cameras moves around the patient to acquire various projections, which are then reconstructed to generate tomographic slices. If the center of rotation does not remain constant throughout the entire orbit of the detector head, artifacts may appear in the reconstructed images.
GT-3 Tomographic uniformity
Tomographic uniformity involves obtaining reconstructed images of a uniform cylindrical source. Planar non-uniformity and collimator inhomogeneity can cause ring artifacts in the cross-sectional slices, which are easily detectable in images of a homogeneous source but are difficult to discern in patient studies. This test is the three-dimensional equivalent of planar uniformity.
