Compensation for attenuation, scatter, and detector response in SPECT reconstruction via iterative FBP methods.

Iterative filtered backprojection (FBP) reconstruction is a fast method for single photon emission computed tomography (SPECT) that can provide simultaneous compensation for nonuniform attenuation, scatter, and distance-dependent detector response. The iterative FBP method was applied to the reconstruction of SPECT images of a chest phantom consisting of nonuniform attenuating media. One hundred twenty projections containing 20 million counts were reconstructed on an image array of 128 x 128 x 64. The accuracy of reconstruction was significantly improved, in terms of concentration ratio, object shape, and noise reduction. Results of this experimental study indicate that interactive FBP can effectively reconstruct SPECT images, while other iterative methods, such as maximum a posteriori probability (MAP), will spend at least ten times more computing effort in the reconstruction on the same computer. The disadvantage of iterative FBP is its inability to model the noise properties of data collection accurately, as compared to the MAP methods.