A motion detection system detects object motion in a medical imaging system. The computer-implemented calibration method includes an automatic calibration process for determining a motion threshold for the object motion detection system, while the object is positioned for imaging by the medical imaging system. The calibration process includes: repeatedly acquiring motion detection data and repeatedly acquiring motion quantification data with a motion quantification system. The motion quantification data are analyzed to determine whether the object was mobile or immobile. If the object was immobile, an object motion threshold for the motion detection system is determined by statistical analysis of the motion detection data. If the object was mobile, the detection and quantification data are correlated for determining an object motion threshold for the motion detection system, the threshold being determined from motion detection data correlated to motion quantification data characterizing an object motion within a predefined tolerance value.
