A system is provided for subject movement compensation during a medical procedure. The system uses passive radiofrequency identification tags associated with a subject, and at least one active RFID reader is positioned to interrogate the position of at least three such passive radiofrequency identification tags so as to triangulate the geometric position of a subject body tissue. The reader generates an output signal corresponding to a distance between said reader and a tag. A microprocessor calculates a displacement of a tag relative to the reader from said output signal to yield a value corresponding to subject movement. A medical device operates in synchronicity with the calculation corresponding to subject movement to compensate for subject movement during a treatment process in essentially real time. A process for subject movement compensation during a medical procedure is also provided.
