The effect of X-radiation on the survival of skin flaps in the pig

Abstract

A COMBINATION of surgery radiotherapy is frequently used in the treatment of malignant disease. By consu'ltation between surgeon radiotherapist, by careful planning, any necessary operation can sometimes be timed take place at the optimal phase for healing in relation the development of radiation effects (Ellis Patterson, I968). More often, however, the surgeon is faced with the need excise a tumour which has recurred following radiotherapy, or treat the late damage resulting from irradiation. The problem then is know how much tissue should be excised in order clear the radiation-damaged area. The radiotherapist can indicate the exact limits of the fields of irradiation. It is much more difficult, however, estimate how much scattered radiation has affected the tissues beyond this how far the blood supply in these areas has been damaged. All surgeons are familiar with the problems of designing local flaps, of getting grafts to take and wounds heal near previously irradiated tissue. In view of the difficulties of studying this in man it would be useful have an experimental system which would be as near the clinical situation as possible. For reasons previously discussed (Patterson, I968), the pig is a suitable experimental animal. The opening of the Churchill Hospital Research Institute in April I97 o provided an environment in which surgeons, radiotherapists radiobiologists could work together on these problems. The Institute has facilities for studying all aspects of malignant disease. This paper describes some of our preliminary results of the short-term radiation effects on pig skin. Assessment was by means of the skin flap preparation on the flank of the pig previously described (Patterson, I968 ). Here a rectangular flap of skin is raised in such a way that all blood supply is divided, except that coming in from a ventrally sited pedicle. The efficiency of this blood supply is then measured by the length of the flap that survives. Alterations in the blood supply as a result of radiation a flap should thus be shown by alterations in the surviving length of the flap. In experiments on the pig for a different purpose some years ago it was found that an intra-vital dye (Disulphine blue), injected intravenously, was a fairly accurate predictor of the survival of skin flaps (Patterson Milton, 1967). This technique was not directly applicable the present experiments, but the dye was injected at varying times after radiation see whether it would provide additional evidence of the state of the blood vessels in irradiated skin. Experimental Design. Large White pigs were paired for age sex. The flank of one of each pair was shaved 24 hours before operation, the other pig being left unshaven. Under a general anaesthetic four flaps, I6 cm. long 4 cm. wide, were marked out on the flank with a gap of 4 cm between each flap. The outlines were lightly scored with Indian ink as a permanent marker. Each flap was then given a single dose of x,863 fads or 2,I32 fads with 250 kVp X-rays (HVL I'3 mm. Cu.). These doses z This paper was presented at the joint meeting of theAssociation of Radiation Research the Netherlands Radiobiological Society held in Oxford in April x97 x.