1. An anti-collision method for a medical imaging system comprising a moveable part moved about a patient, comprising: detecting a surface of an external object by a sensor connected to the moveable part; transmitting the detection to a control device; calculating a distance between the moveable part and the surface of the external object according to the detection by the control device; and controlling a movement of the moveable part based on the calculated distance by the control device to prevent a collision of the moveable part with the external object, wherein a coordinate system calibration between the imaging system and the sensor is performed prior to recording an image data of the patient.