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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.