[The radiation load of the Swiss population due to radiodiagnosis].

It is recommended that the so-called "genetically significant dose" (GSD) be applied as a quantitative index of the radiation exposure of the genetic material of a population, i.e. the dose which, if received by every member of the population, would be expected to produce the same total genetic injury to the population as do the actual doses received by the various individuals. The GSD of the Swiss population for the year 1971 was calculated on the basis of information received from physicians concerning approximately 60 000 patients. Exeripmental determination of the gonad dose was done in various hospitals with the aid of TLD dosimeter, and sensitive high-pressure and normal-pressure ionization chambers. The results show that the annual rate of increase of X-ray diagnostic examinations is 3-4% in Switzrland as elsewhere. The GSD for Switzerland amounted in 1971 to 42-43 mrad per person as compared with 22 mrad in 1957. The "annual mean marrow dose of a population" can be calculated from the single doses received from each part of active bone marrow irradiated in the course of an X-ray examination and, as in the case of the genetically significant dose, from the demographic figures mentioned. The annual mean marrow dose (1971) for the Swiss population was tentatively calculated using the values of the mean marrow dose per examination of the UK survey of 1957/58 and amounts to about 121 mrad. Barium meal contributes about 30% of the total, while intravenous pyelography, carium enema, lumbar spine and mass miniature radiographies each account for about 10%.