Collective doses to the Swedish population from panoramic radiography and lateral cephalography.

A questionnaire was sent to all dental offices in Sweden equipped with panoramic and cephalographic x-ray units. Data were obtained for estimating the energy imparted from panoramic radiography and lateral cephalography during 1984 to the Swedish population. There were two units with intraorally placed focus among the 121 panoramic units studied. Approximately half of the panoramic radiographs, totally 79,000, were exposed on individuals younger than 20 years of age. Ninety-three cephalographic units were used to expose 40,000 lateral cephalograms, of which 10 per cent were exposed on children less than 10 years old and 12 per cent on adults. The energy imparted was estimated using the collected data, relative depth dose values and conversion factors from the literature. Mean energy imparted per panoramic examination was 0.50 mJ, and per cephalogram 0.43 mJ. From the panoramic and cephalographic examinations the energy imparted to the Swedish population was 40 J and 17 J, respectively. The corresponding collective effective dose equivalent to the population would be 0.75 manSv and 0.43 manSv, respectively. As a comparison, the collective effective dose equivalent from the annual natural irradiation including radon irradiation from dwellings is about 6.8.10(4) manSv.