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A 2-D mapping (or Bullseye Display) of the 3-D myocardium function from myocardial perfusion SPECT (single photon emission computed tomography). For a normal heart function, the grey scale of the circular display would be relatively uniform. On the left is the conventional reconstruction of the myocardium function, where two defects are barely seen. On the right is the result of our quantitative reconstruction, where the two defects are not only clearly seen, but also quantitatively defined in their sizes and intensities. The reconstruction is of 128 cubic size. Our current quantitative reconstruction is based on MAP-EM (maximum a posteriori probability with expectation-maximization) iterative algorithm.

With the explicit inversion formula of Novikov for the attenuated Radon transform, quantitative chest SPECT (i.e., with additional scatter compsenation and collimator blurring correction) can be reconstructed by an ultrafast speed because of the analytical inversion nature. In parallel-beam collimation geometry, the reconstruction accuracy and ultrafast speed have been observed. For varying focal-length fan-beam collimation geometry, our recent results are very encouraging, see our publications.