Patent ID: 6956196

Claim:
Apparatus for detecting, measuring and correcting positional deviations of at least one area of a subject along one or more subject position axes, from a prior spatial position at a prior time to a later spatial position at a later time, which apparatus comprises: a) a distance-measuring component which at least 1) continuously or intermittently gathers information corresponding to the spatial position of the area along a first subject position axis, the information being comprised of a phase difference between two oscillatory signals, the first of the signals A) corresponding to the intensity modulation of, or B) bearing a phase relationship to, a first amplitude modulated beam of radiation before the first beam of radiation is incident upon the area, and the second of the signals A) corresponding to the intensity modulation of, or B) bearing a phase relationship to, the first beam of radiation after the first beam of radiation has been reflected by the area, and 2) derives the later spatial position, and optionally the prior spatial position, of the area along the first subject position axis from the information gathered in 1); b) storage means for storing information corresponding to the prior and later spatial positions of the area; c) a support upon which the subject may lie; d) calculating means for determining, from the stored information, a deviation in spatial position of the area from its prior spatial position along the first subject position axis and translatory motion of the area which will restore the area to its prior spatial position along the first subject position axis, and generating at least one repositioning signal which transmits information corresponding to the translatory motion of either the support or the area necessary to restore the area to its prior spatial position along the first subject position axis; and e) a position controller which can at least reposition the support in response to the repositioning signal.