Statistical tomographic reconstruction: How many more iterations to go?

Single-photon emission tomography (SPET) is a popular, commonly used method to image the three-dimensional distribution of a radiopharmaceutical within the human body. In clinical studies, filtered back-projection (FBP) still seems to be the method of choice for tomographic reconstruction, although most manufacturers of gamma cameras include iterative statistical reconstruction methods in their basic software package. Quite a lot of progress in the development of these iterative methods has been made during the past few years and promising typical clinical examples have been shown. But there is still a need for a clinical comparison of the new and the old methods in patient studies. The processing time, even on state-of-the-art computer systems, may be the most prohibitive factor for using the more advanced iterative reconstruction methods including scatter and attenuation correction.