DIVISION OF BIOPHYSICS: RADIATION HAZARD TO PATIENTS IN BRITAIN FROM RADIOLOGICAL PROCEDURES*

Abstract

Results of a survey are reported of radiation doses in general diagnostic radiology, mass miniature radiography (photofluorography) of the chest, dental radiography, radiotherapy of nonmalignant disease, and radiotherapy of malignant disease, including the uses of radioisotopes. A field survey included measurements in 130 hospitals and chest clinics selected to give a representative crosssection of radiological practice. Male gonad doses were measured directly by an ionization chamber placed in contact with the scrotum. Female doses were derived indirectly by measuring the scatter dose (or the primary dose if the chamber was in the beam) at a point on the anterior abdominal wall to the level of the iliac crest and relating this to the ovary dose by supplementary measurements made on a specially constructed model. ln pelvis, lumbar spine, and lumbo-sacral joint examinations of adult males, measured gonad doses per examination ranged from less than 0.1 mr to more than 10,000 mr, with a mean dose of 387 mr. In examinations of the chest, heart, and lung, measured gonad doses ranged from 0.01 mr to 100 mr in adult males, and to 500 mr in adult females. The cause of high doses in this case was the use of needlessly largemore » x- ray beams and on some occasions a complete absence of diaphragms or cones. In the 1131 chest, heart, and lung examinations measured, 10% of the exposures on males and 51% of those on females included direct gonad exposure. Almost 1/4 of the 6000 radiographs of females used a beam area at least twice that of the film. To estimate bonemarrow doses in diagnostic radiology, depth-dose data were obtained by measurements at 12 marrow sites using a wax-impregnated skeleton as a model. It was evident that the examinations ranking high in marrow dose were not the same as those which contribute most to the gonad dose. A large part of the total dose is contributed by barium meal, mass miniature radiography, and chest examinations. Because active marrow is widely distributed throughout the skeleton, it seems unlikely that the results for any one type of examination will show variations as great as those for the gonad dose, where great differences can be caused by a small shift of the beam edge. It seems unlikely that improvements in technique can bring about a reduction in the marrow dose as dramatic as that suggested as practicable in the gonad dose, limitation of beam size being the most important reducing factor. (TCO)« less