The Relative Sensitivity of the Kidney to Irradiation

THE successful application of radiotherapy is due in large measure to the broad foundation laid in the exhaustive study of the immediate metabolic reaction and the tissue changes produced in man and the experimental animal. The literature on the immediate response of the body as regards metabolism, normal tissue and tumors is abundant, but that relating to chronic or terminal changes is far from being comprehensive. In recently reported experimental work on dogs it was demonstrated that a fatal nephritis could be readily produced by the application of hard X-rays through the body wall. This was accomplished both with single massive doses and with repeated smaller doses. In the first experiments large perforating ulcers were produced in the abdominal wall and the animals were lost from extensive destruction of the intestine, but the technic has been developed to the point where little or no hair is lost and only an occasional scar or ulcer of the intestine is found. However, when an area 10 cm. square over one or both sides was irradiated the corresponding adrenal and ovary were always within range, and portions of the spleen, liver, pancreas and intestine were in the area when the liver and heart were exposed. From the animals lost in the early part of the work three to five days after irradiation the acute changes were in order of severity as follows: (1) intestine, (2) adrenal, (3) kidney, (4) spleen, (5) liver, (6) ovary and (7) pancreas. These acute changes have been adequately described. In this work interest has been centered on the chronic nephritis produced and the resulting renal insufficiency. It is the object of this paper to determine the relative susceptibility of the kidney and to evaluate the dangers of the clinical application of deep therapy over the kidney area. The experiments were all done on dogs, and 200 kilovolts, 30 milliamperes, with filtration of 1 mm. copper and 1 mm. aluminum at 50 cm. skin distance was used. Up to the present time some seventy-five animals have been used and the changes described resulted from irradiation through the abdominal or chest wall either in the kidney work already reported or in one of the two series of experiments now in progress, that is, irradiation over the liver and over the heart, both of which will be reported in detail at a later date. The chronic lung lesions produced by deep X-ray have been described, both in the experimental animal and in patients, by Davis (1), Groover and Christie (2), Evans and Leucutia (3) and others. The findings reported are in agreement. Our observations have added nothing except to demonstrate the relative high resistance of the lung in a large series of animals. Weekly applications over the chest for periods of from 15 to 30 minutes during two to five months produced extensive fibrosis only in the pleura or periphery of the lobes. No infection was noted in this series (Fig. 1).