Radiation exposure in dental radiology: a 1998 nationwide survey in Switzerland.

OBJECTIVES: To measure the frequencies of dental radiological examinations in Switzerland and to determine the associated collective radiation doses. METHODS: To evaluate the frequencies, a sample of 376 dental practitioners and other institutions performing dental radiology were requested to fill in questionnaires designed to measure, amongst others, frequencies of dental radiodiagnoses according to type of examination, patient age and gender, dental specialty and type of surgery. The associated collective radiation doses were determined by multiplying the relevant frequencies with dose estimates obtained from recent measurements and calculations. RESULTS: The total number of dental examinations performed in Switzerland in 1998 was 4.1 million (581 per 1000 population). Periapical, bitewing and panoramic radiographs were the most frequent types of dental examinations. The collective dose associated with dental radiology was 71 person.Sv. This amounts to an annual average effective dose to the population of 10 muSv per caput, which is in agreement with the figures reported for countries of similar healthcare level. Various features such as the age distribution of the radiographed patients, the forms of collimators used, film consumption and the use of digital imaging systems are presented. CONCLUSIONS: Several recommendations for dose reduction are made. These include the re-evaluation of the patterns and justification for prescribing some particular types of dental examinations as well as the avoidance of unnecessary irradiation by the use of rectangular collimation and high sensitivity F-speed films.

Adult reference levels in diagnostic and interventional radiology for temporary use in Switzerland.

This work aims at establishing a set of diagnostic reference levels (DRLs) for various types of examinations performed in diagnostic and interventional radiology. The average doses for 257 types of radiological examinations were established during the 1998 nationwide survey on the exposure of the Swiss population by radiodiagnostics. They were calculated using appropriate dosimetric models and average technical parameters. The DRLs were derived from the average doses using a multiplying factor of 1.5. The DRLs obtained were rounded and compared to the data reported in the literature. The results are in most cases comparable to the DRLs determined by the 3rd-quartile method. These discrepancies registered in some cases, particularly for complex examinations, can be explained by significant differences in the protocols and/or the technical parameters used. A set of DRLs is proposed for a large number of examinations to be used in Switzerland as temporary values until a national dosimetric database is set up.

X-ray imaging of the chest in Switzerland in 1998: a nationwide survey.

The use in Switzerland of three chest X-ray imaging modalities is studied. The frequency and dosimetric aspects associated with chest radiography, chest CT, and photofluorography are investigated and the Swiss figures are compared with those of other countries. The frequencies are established by means of a nationwide survey performed in 1998, whereas the doses are determined by modelling, based on the technical parameters of the examinations. The annual frequencies of chest radiography, chest CT, and photofluorography are 201, 7, and 7 per thousand population, respectively. The standard effective doses related to these three types of examinations are 0.057, 9, and 0.13 mSv, respectively. The collective dose associated with chest X-ray imaging amounts to 606 man.Sv, representing 8.5% of the total collective dose due to diagnostic and interventional radiology. The geographic and seasonal variations, as well as the distribution with the medical specialty and with the age of the patient, are established. The Swiss results compare well with the average data published in the literature for other countries of similar health care level. Chest radiography shows a significant decrease with time. It dropped by a factor of 2 in 20 years. The conformity of the indication of chest X-ray modalities with referral guidelines is also investigated.