Survey of dental radiographic equipment and radiation doses in Finland.

The radiation dose exposure, and the faults in about 1,700 dental units inspected at dental surgeries by the Finnish Centre for Radiation and Nuclear Safety in 1981-1985, were analysed. The mean value of skin doses in the bite-wing projection was about 6.2 mGy, the range 0.5 to 151 mGy. The mean energy imparted per bite-wing examination was estimated as 0.68 mJ and that per panoramic examination as 1.2 mJ. That gives a total imparted energy of about 600 J per year for conventional dental examinations and about 420 J per year for panoramic examinations. This gives a total of 0.13 mJ from conventional and 0.089 mJ from panoramic examinations per inhabitant per year. The collective effective dose equivalent was calculated as about 9 manSv for conventional dental examinations and about 6 manSv for panoramic examinations. Twenty per cent of units had some fault which was capable of decreasing radiation safety. Forty per cent of units were served reparation orders or other remarks were made in inspection documents. Large doses were usually accounted for by incorrect film processing and malfunction of the exposure timer.