1. A system for location of a patient's body with spatial points on a treatment or diagnostic apparatus in registration with image data from an image scanner, the image scanner having a scanner coordinate frame and providing the image data of at least a portion of said patient's body scanned by said image scanner to said computer system to develop scanner marker coordinates in the scanner coordinate frame of scanner index markers located on said at least a portion of said patient's body, and to develop scanner target coordinates in said scanner coordinate frame of at least one target in said at least a portion of said patient's body, said system comprising: a computer system to process camera data and the image data from the image scanner; a camera system comprising two or more cameras, each having a field of view that comprises at least a portion of the patient's body on the treatment or diagnostic apparatus, said camera system indexing positions of the spatial points within the field of view, having at least one reference point in a known position with respect to said treatment or diagnostic apparatus with reference coordinates that are known in said camera system, the camera system providing camera data to the computer system to develop optical marker coordinates in the camera coordinate frame of optical index markers detectable by said camera system in the field-of-view and located in the same position on said patient's body as said scanner index markers, and whereby said positions of said optical index markers are known with respect to said at least one reference point; transformation means associated with said computer system to transform said scanner marker coordinates to said optical marker coordinates, and whereby said scanner target coordinates are transformed to camera target coordinates so that the position of said at least one target position is determined with respect to said at least one reference point of said treatment or diagnostic apparatus.