Speaker: John A. Roberts

Title: The geometric transfer function component for scintillation camera collimators with straight parallel holes.

We are currently building a Monte Carlo simulation for conventional and rotating slant hole SPECT imaging. I will be discussion one component of that simulation, the geometric response function of the collimator with references to a paper by Metz et al. Metz et al. derive analytic solutions for the geometric response of typical parallel hole collimators. I will use their approach to derive the geometric response for slant hole collimators.

Title: The geometric transfer function component for scintillation camera collimators with straight parallel holes.

Authors: Charles E. Metz, Frank B. Atkins and Robert N. Beck.

Phys. Med. Biol, 1980, Vol 25, No. 6, 1059-1070

Abstract:

A theoretical approach has been developed that allows the geometric transfer component for conventional scintillation camera collimators to be predicted in closed form. If transfer function analysis is to be useful in describing imaging system performance, the image of a point source must not depend on source position in a plane parallel to the detection plane. This shift invariance can be achieved by analysis of the system response in terms of an effective point spread function, defined as the normalized image of a point source that would be obtained if the camera collimator were uniformly translated (but not rotated) during image formation. The geometric component of the corresponding effective transfer function is shown to be expressed simply by the absolute square of the two-dimensional Fourier transform of a collimator hole aperture, with the spatial frequency plane scaled by a factor which depends on the collimator length, source-to-collimator distance, and collimator-to-detection plane distance. Closed form algebraic expressions of the geometric transfer function have been obtained for all four common hole shapes (circular, hexagonal, square, and triangular). Monte Carlo simulations and experimental measurements have shown these theoretical expressions to be highly accurate.