A microcomputer-based system for radiotherapy beam compensator design and patient contour plotting.

A microcomputer-based system for radiotherapy beam compensator design has been constructed. A patient surface measuring device which projects a grid pattern on the patient is attached to the collimator of a therapy treatment simulator. A linear motion potentiometer, pivoted at one end on a ball joint attached to the collimator, is extended to touch each grid point in turn. The extension of the potentiometer is monitored by a microcomputer which calculates the coordinates of the patient's surface as each grid point is entered. A template for compensator construction is subsequently printed on the microcomputer printer. The patient surface profile along any grid line can also be plotted and used in conjunction with the compensator data to produce an isodose distribution for the compensated field.