For the estimation of the population doses and risks of stochastic effects to assistants who hold animals during veterinary X-ray examinations a random survey of hospitals and clinics was carried out concerning age distribution of such assistants by groups of facilities.The average organ and tissue dose per examination was evaluated from the experimental data using mean technical factors such as X-ray tube voltage, tube current and field size based on the results of a nationwide survey.The population doses to the assistants were calculated to be about 14nSv per person per year for the genetically significant dose, 3.5nSv per person per year for per caput mean marrow dose, 3.3nSv for the leukemia significant dose and 4.5nSv for the malignant significant dose, respectively. The total risk of stochastic effects to the Japanese population from holding assistants was estimated using population data and it was estimated to be less than one person per year, but the cancer risks to a number of the assistants were estimated to be more than 4×10-5.

For the estimation of dose equivalent and collective dose equivalent from veterinary radiographic diagnosis a nationwide survey of randomly sampled hospitals and clinics was carried out concerning number of radiographs and fluoroscopic examinations performed in 1985-1986.The resultant annual number of radiographs was 2, 310 thousand for small animals and 110 thousand for large animals with a total of 2, 420 thousand. The total time of fluoroscopic examination was 3, 000h.Animals were exposed to diagnostic X-rays according to technical factors of typical radiographic and fluoloscopic examinations obtained from a nationwide survey to estimate the dose equivalent to holding assistants whose doses were determined using ionization chambers and thermoluminescent dosimeters placed at the position of the chest pocket.The resultant annual collective dose equivalent was 1.06 man Sv for radiographs and 0.34 man Sv for fluoroscopic examinations with a total of 1.40 man Sv (140 man rem). The average annual dose equivalent per person was estimated to be 78μSv.

Present report deals with a computer program which provides a method to calculates absorbed radiation dose of various organs from radionuclides internally distributed in the body. The program is based on the MIRD method and a transformation method which estimates absorbed doses for physiques different from the MIRD phantom, for example, those for Japanese people. Specific absorbed fractions for arm bones and leg bones were calculated in terms of the buildup method in order to estimate Japanese red bone marrow dose. Specific absorbed fraction for breast was estimated in the MIRD phantom by using the buildup method. The program list will be sent by request.

A little more than 20,000 examinees of x-ray mass survey of gastric cancer and the controls were followed up from 1960 to 1977. Cumulative doses of x-rays were calculated for each examinee, and a collective dose in person-year-rads was constructed. Incidence of leukemia was ascertained from Miyagi Prefectural Cancer Registry. Seven cases of leukemia were found out of 242,689 person-year-rads in the irradiated population, and 9 cases out of 273,344 person-years in the controls. Incidence rate in the two groups was identical. Therefore, the risk of this mass survey was disproved.