Experimental Measurement of Axial and Transaxial Resolutions of a Slit-Slat Collimator and Comparison to Theoretical Expectations

A slit-slat collimator combines a slit parallel to the axis of rotation of a gamma camera with a set of parallel septa evenly spaced in the axial direction. Since the system geometry is similar to pinhole and parallel beam, it is expected that transaxial resolution is described by pinhole relationships and axial resolution is described by parallel-beam relationships. Axial and transaxial resolutions were investigated analytically, through Monte Carlo simulations, and experimentally. A prototype slit-slat collimator was constructed from pre-existing materials. Point source data were collected over a range of source positions, and for values of the slit width, septal spacing, and septal height that varied by factors of two. Experimental FWHM resolutions agree with the theoretical and MC results.