Computer generation of high-energy x-ray dose distributions

A computer program for the generation of high-energy x-ray dose distributions has been developed. The program takes account of the fact that the x-ray beam profile, as affected by penumbra, wedges, beam blocks, or flattening filters, is one of the prime determinants of the dose distribution. Doses from primary and scattered radiation are calculated separately by using published tissue-air ratio (TAR) and scatter-air ratio (SAR) data. The dose from scattered radiation is determined by dividing the x-ray field into a series of scattered strips and summing the contribution from each. Wedges or beam blocks are taken into account simply by earning their actual coordinates and linear attenuation coefficients. The program may be used to design wedges, beam blocks, or flattening filters prior to fabrication. Complete libraries of dose distribution for 60Co, 2-, 4-, and 6-MV x rays have been generated.