OPTIMAL-DESIGN OF PLANAR-CONCAVE COLLIMATORS FOR SPECT - AN ANALYTICAL APPROACH

In this paper we present an analytical tool for the design and optimiz ation of planar-concave collimators for SPECT. We conclude that a sing le general planar-concave collimator that eliminates the non-isotropic blurring for all SPECT applications does not exist. On the other hand , it is possible to achieve pseudo-optimal collimators for different c linical applications by a careful choice of the design parameters. By classifying the clinical applications into two groups, for instance bo dy and brain studies, the non-isotropic blurring for most SPECT situat ions may be dramatically reduced by means of planar-concave collimator s. The results based on Monte Carlo simulations show that the shape of the point source response function of the reconstructed image obtaine d from the planar-concave collimator is more isotropic than that obtai ned from a conventional parallel-hole collimator. Specifically, the ra tio of the FWHM of the reconstructed point response function in the ra dial and tangential direction is increased from 0.5 for the parallel-h ole to 0.85 for the planar-concave collimator for sources 200 mm away from the centre of rotation.