An investigation of the stationarity of the 3D modulation transfer function of SPECT

This study evaluated the rotational symmetry and stationarity of the three dimensional (3D) modulation transfer function (MTF) of single photon emission computed tomography (SPECT). The MTF's dependence on methods of averaging opposing projections before reconstruction, and attenuation correction was also determined. Point spread functions (PSF) in scattering media were obtained by placing a point source at varying radial distances from the center of three differently shaped water filled phantoms. Opposing projections were combined using either arithmetic or geometric mean averaging. The data were reconstructed, 3CD FFT'ed, and a 3D MTF was calculated. Three different methods of partial attenuation compensation were studied