Correction of dose distribution for oblique incidence in 6 mv x-rays therapy

A correction factor of 6 MV X-rays for the obliquity correction by isodose curve shift method was estimated from the inverse square law. The correction by the factor was performed within a 3% error. Correction factors of 60Co gamma-rays for different SSD's and of X-rays of up to 24 MV were also estimated.