Using Monte Carlo based system matrix for increasing detection efficiency in small animal SPECT

The paper is investigating the capability (accelerated fully 3D Monte Carlo) AF3DMC reconstruction technique to reconstruct image with good spatial resolution even when collimator pinhole aperture diameter is increased. The following are discussed: the concept of image reconstruction in small animal SPECT; system description; planar performances as function of the aperture diameter collimator pinhole using simulated data; tomographic performances as function of the aperture diameter collimator pinhole using simulated data; and tomographic performances as function of the aperture diameter collimator pinhole using real data. Results show that when using a pinhole SPECT and reconstructing images using a Monte Carlo based system matrix, it is possible to increase the aperture of the pinhole diameter by a factor of 3 going from 0.5 mm to 1.5 mm, increasing so the detection efficiency of the system by a factor of 6 and this without degrading the spatial resolution of the reconstructed images.