Analytical derivation and experimental verification of a sensitivity formula for slit-slat SPECT collimation

The formula g = wd
²
/[4pia(d+t)h] sin
²
thetas is derived for the sensitivity of a slit-slat collimator. Both Monte Carlo and experimental data confirm the expected dependence of g on the parameters, especially the distance from the plane of the slit h and the off-axis angle thetas. To refine agreement, a formula for the sensitivity-equivalent slit width is derived to account for slit penetration. At least at low energy its predictions agree well with Monte Carlo data and its use improves agreement with experimental data.