Follow-up study of patients treated by x-ray epilation for tinea capitis. Estimation of the dose to the thyroid and pituitary glands and other structures of the head and neck.

This study is a further investigation of radiation dose to various head structures in the children given X-ray therapy for tinea capitis (ringworm of the scalp). In this work, estimates of the dose to the thyroid and pituitary gland were obtained with lithium fluoride thermoluminescent dosemeters using a child's head phantom. Doses were also measured for the parotid gland and several skin sites where skin tumours developed in the irradiated cases. In a previous study, brain and scalp doses of 140 and 500-800 rad had been estimated for the treated group using this same head phantom. In this work dosemeters were also placed in the same brain locations so that comparisons could be obtained between the two studies. The thyroid dose was estimated to be 6 +/- 2 rad and the pituitary dose was 49 +/- 6 rad for the conventional tinea capitis treatment. The dose to the parotid gland was 39 rad and the dose to skin sites on the face and neck where tumours occurred ranged from 20 to 40 rad. The data for the thyroid adenoma response from this and other studies involving irradiation of children suggests a linear dose-response relationship within the first 30-40 years after exposure with a risk of about 0-04% per rad.