3D positioning method for radiotherapy treatment

A new method of 3D multi-spot surface profiling for patient's positioning is presented in this paper. In the approach, an encoded pattern structured light is used to project onto the target to be positioned, which is typically part of the patient surface. A single camera is used to image the projected light beams and the range data from camera to the target points can be extracted from the image of the deformed pattern. Because the light pattern is encoded, the correspondence between the projected beams and imaged beams is easily determined and, hence, the range data can be calculated quickly. The 3D sensing method here is based on the active light illumination triangulation. A detail description of the method is given, including system configuration, algorithms for solving the correspondence problem, reconstruction of the point's 3D position, calibration and experimental results, etc. One of the features of the system is extremely simplicity in hardware. And there is no movement part in the system. The encoded grid beam pattern makes it possible to solve the problem of the correspondence between the illuminated spots on the patient and their image points on the image plane. Also, the 3D reconstructed coordinates can be obtained from only one picture frame captured and the time consuming for computer is reasonably reduced.