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

Abstract

The effects of radiation doses to various head structures in children given X-ray therapy for tinea capitis (ringworm of the scalp) were studied. Estimates of the dose to the thyroid and pituitary gland were obtained with lithium fluoride thermoluminescent dosimeters using a child''s head phantom. Doses were also measured for the parotid gland and several skin sites where skin tumors developed in the irradiated cases. In a previous study, brain and scalp doses of 140 and 500-800 rads were estimated for the treated group using this same head phantom. Dosimeters were also placed in the same brain locations so that comparisons could be obtained between the 2 studies. The thyroid dose was estimated to be 6 .+-. 2 rads, and the pituitary dose was 49 .+-. 6 rad for conventional tinea capitis treatment. The dose to the parotid gland was 39 rads and the dose to skin sites on the face and neck where tumors occurred ranged from 20-40 rads. The data for thyroid adenoma response from this and other studies involving irradiation of children suggests a linear dose-response relationship within the first 30-40 yr after exposure with a risk of about 0.04%/rad.