Measurements of exposure dose in intravenous pyelography examination

Radiation doses to the foetal and adult gonads, and to the kidneys in intravenous pyelography (IP) examination were estimated. The trunk sizes around the kidney and exposure factors were searched on about one hundred patients under IP examination. On the basis of these data, several model phantoms were manufactured and the exposure doses were measured at the kidneys and the gonad positions in these phantoms, while the possibilities in minimizing the amount of dose received during IP examination were stressed from different aspects. The formula of the kidney position in relation to the thickness and width of trunk were obtained in linear expressions. The exposure dose to the kidney was estimated to be less than 200 mrad. This indicated that the kidney dose due to x-ray examination is negligibly small for inducing the radiation nephritis. Male gonad dose was estimated to less than 30 mrad. The female gonad dose outside the radiation field was estimated to be lower by a factor of 1/4 to 1/5 than that of 160 mrad at largest due to direct beam. The foetal gonad dose was less than 630 mrad and this causes whole body irradiation with high possibility for malformation and carcinogenesis, and with high genetically significant doses. In IP examination required during late pregnancy, the posteroanterior projection technique could be utilized, taking the advantage of reduction in foetal gonad dose by 1/3. The use of high sensitive screen could reduce the exposure dose down to 1/6 within the diagnostic capacity. (auth.)