Experiments with Fractionated X-irradiation of the Skin of Pigs II. – Fractionation up to Five Days

Fifteen fields on one pig were irradiated with 1, 2, 2, 3 and 5 fractions in 1, 5, 2, 3 and 5 days respectively. Skin reactions were recorded up to 80 or 100 days, so that the doses which produced equal reactions could be assessed. Three degrees of damage were analysed for early, medium and late reactions. As an example, the doses to produce one level of reaction over 30–85 days were respectively 2,050, 2,560–2,750, 2,750, 3,360 and 4,060 rads for the fractions listed above. The corresponding values of “DQ” = (Dn — D1)/(n —; 1) were high, 500–700 rads. The values of (Dn − D1)/(n − 1) became smaller with larger numbers of fractions. Two pigs were irradiated to investigate the “reciprocal vicinity” effect. It was found to be small for the field arrangements used, but the sensitivity of pig skin increased in the dorso-ventral direction and corrections were sometimes necessary. Two pigs were irradiated with pairs of equal doses separated by 0 to 24 hours. A recovery pattern was observed similar to that found in cell culture by Elkind and Sutton (1959), but less well resolved. It is not established that skin damage is entirely due to loss of cellular reproductive integrity, but from the practical point of view the empirical relation between dose and skin damage in pigs is similar to that found in patients, and is in agreement with other work on mouse skin and mouse intestinal death, but not with cell survival work on haemopoietic cells.