A system and method are provided for aligning a field of view (FOV) of a movable part of a medical device with a desired region on a subject's body. In the system, a position detecting unit detects an identifiable optical front projected on the subject's body and at least partially overlapping with the desired region and generates information corresponding to a spatial position of the identifiable optical front. From the information, a processing module determines the spatial position of the identifiable optical front with respect to a known position of the FOV and generates an instruction set that corresponds to one or more mechanical adjustments of the movable part to change a position of the FOV from the known position to the spatial position of the identifiable optical front. An executing module directs a moving mechanism of the movable part to carry out mechanical motions according to the instruction set.