A unified reconstruction algorithm for conventional 2-D acquisition geometry

To improve detection sensitivity, fan- and general converging-beam collimations are usually used in SPECT imaging. Development of the associated reconstruction algorithms is currently a research topic. In this paper, the authors present a unified harmonic decomposition reconstruction algorithm for general converging-beam geometry, including parallel- or fan-beam collimation as a simplified example. Compared to other harmonic transform algorithms, the presented one has the advantage that the tedious computation of the Hankel transform, the Chebyshev polynomials or the Bessel functions is not necessary. In fact, the current algorithm can be regarded as an alternative implementation of the conventional FBP algorithm in terms of harmonic decomposition. The implementation is easy and the computation time is comparable to the FBP algorithm. The reconstructed images have the same quality as that of the FBP. In addition to the advantages above, the developed algorithm is able to invert the uniformly attenuated Radon transform which has a significant impact in quantitative SPECT imaging.