A gamma camera system and method are described which use multiple point sources to detect inaccuracies in detector translational and rotational alignment. An implantable medical device detects the arrhythmic events. This spatial beat frequency corresponds to misalignment-induced aliasing of spatial frequencies associated with the first subset of the array of proximity connectors and the second subset of the array of proximity connectors. On movement of the lift cage the code carrier slides in the sliding guide past the sensor.