A device for attaching a collimator to a radiation detector. A number of cleats are mounted at the radiation detector for cleating the collimator to the radiation detector and a latch means serves for latching the cleated collimator against rotation. Also a collimator cleating detection means is associated with the cleat means for detecting incorrect cleating of the collimator and a collimator latch detection means is associated with the latch means for detecting incorrect latching of the collimator.