An exemplary embodiment of a 3D camera system for a patient positioning and monitoring system is described. In the system a pair of image detectors are provided where the image detectors are each associated with a heater thermally connected to conducting pads provided at the periphery of the image detectors. The heaters and conducting pads act to contain the image detectors in a substantially constant temperature micro climate thereby preventing external temperature variations from causing the relative positions of the image detectors to change so as to record portions of images as different pixels and hence reduce the consistency with which the identification of matching portions of images obtained by the image detectors can be utilized to determine the 3D positions of imaged objects.
