Resolution recovery in ectomography using filtered backprojection

The aim of this study was to implement resolution recovery (RR) during reconstruction of images acquired with the scintigraphic method of ectomography. Ectomography is a form of limited view angle tomography. During acquisition the detector is stationary and at a constant distance from the object. Consequently, the point-spread function (PSF) varies between reconstructed section images, but is constant within each section. During reconstruction it is possible to deconvolve projection images with the inverse PSF weighted according to the distance of each section from the detector. Reconstruction was performed using filtered backprojection (FBP). A function describing the PSF at any distance from the detector was determined, the inverse calculated, weighted according to signal/noise and used to modify a ramp filter. In real data RR a significant improvement in resolution was obtained without additional artifacts when compared to standard FBP. In conclusion FBP with resolution recovery (RR-FBP) can be implemented in ectomography.