The Effect of Irradiation in High Doses on Parotid Glands

On radiation therapy of malignant tumours in the head and neck region, the salivary glands are often situated in the radiation field. Ten patients undergoing radiation therapy with high doses for tumours in the region of nasopharynx, lingua and bucca have been examined with respect to the function of the parotid glands. The glands received doses of 4 400-7 200 rad, and the function has been investigated by sialographic and sialometric methods. The sialograms show that one year or more after irradiation the parotid glands have a significantly smaller projected area than the non-irradiated glands. The irradiated glands had a sparser duct system than the non-irradiated ones. The sialometric examinations showed that all the irradiated glands stimulated with 1 % citric acid produced very little saliva. The secretion was in all cases remarkably lower than in a normal material, and in most cases only a few drops were collected during 10 min. In spite of a marked decrease in secretion at the end of the irradiation treatment the size of the glands was still unchanged. Only a certain time after irradiation was the decrease in size observed. The reason for this is discussed.