LATE RADIATION-DAMAGE TO PIG SKIN - EFFECTS OF OVERALL TREATMENT TIME AND NUMBER OF FRACTIONS

The severity of skin contraction in a previously delimited treatment field has been used as a measure of late radiation damage to pig skin. Total treatment doses were given as 6, 14, and 30 fractions over 39 days or as 6 fractions over 18 days. Iso-effect curves for severe linear field contraction showed that no simple mathematical formula could be used to calculate safe 'tolerance' doses when fractionation regimes were modified. The results do indicate that for a given level of acute damage, late damage was increased by changing from 5 to 2 fractions per week. These findings are similar to those obtained from surveys in men.