Presented here is a comparison of several detector-collimator combinations for rectilinear scanners with 7.5 and 12.5 cm diameter detectors and a scintillation camera. The comparison is based on the foregoing figure of merit using plane spread functions to compute the MTF values and 'sheet' sources of radioactivity to determine sensitivity. It is emphasized that the figure of merit applies only to the detector-collimator subsystem and not the entire imaging system. While many other variables affect the overall process of pattern recognition on scans, the choice of detector-collimator is a major consideration.