Optimization of dose distributions in moving-strip therapy using a minicomputer.

Optimized 60-Co dose distributions for the moving-strip technique were calculated for 3 patients using a PC-12 minicomputer program which corrects for field obliquity and changes in patient thickness. Beam profiles were measured using an ionization chamber in a water phantom. A Masonite phantom was constructed to simulate a patient and used to measure optimized and unoptimized midplane dose distributions by thermoluminescent dosimetry. Measured midplane doses agreed with computer-calculated doses within experimental error. The computer optimization technique improved dose uniformity, reducing the midplane dose variation from plus or minus 12-13% to plus or minus 3-4%.