| A computerized biostereometric system useful for determination of surface topography is described. A CCTV camera, mounted in the blocking tray slot of a teletherapy simulator or unit, images a pattern of dots, projected by the collimator light and distorted by the patient's topography. The image is "dithertized" and fed into a microcomputer. Because the CCTV camera is mounted in the blocking tray, it can rotate with the unit, determining the topography from any gantry or collimator angle. Entry of data points for calculation is computer assisted. Overall measurement accuracy of body surface height is well within 2mm (measurement precision is 0.4 mm). The system has been tested in a hospital setting and is in clinical use for design of optimized compensating filters in radiation therapy. Additional application may include: irregular field dose calculations, pencil beam calculations, and computation of the equivalent square field. |
