Implementation and preliminary investigation of analytical methods for correction of distance-dependent resolution variation and uniform attenuation in 3D drain SPECT

Spatial resolution variation as a function of distance from collimator surf ace in single photon emission computed tomography (SPECT) is a major obstac le for quantitative imaging. This work investigated two analytical inversio n methods for correcting the distance-dependent resolution variation, as we ll as uniform attenuation in brain SPECT studies. The first one utilizes an accurately measured resolution variation kernel, but derives an approximat ed inversion formula. The second one derives an accurate inversion formula, but approximates the resolution variation kernel. Reconstructed images usi ng the first method showed a better resolution recovery at the periphery of field-of-view (FOV), consistent with the theory that the inversion formula is approximated for far-field regions. The second method restored resoluti on better at the central area of FOV, consistent with the approach that the resolution kernel is approximated for near-field regions. The second metho d is more sensitive to the approximation. The first one is more robust to t he approximation and, therefore, can be a better choice for quantitative SP ECT imaging.