The results of Canada's National Capital Region 1999-2000 dental X-ray survey

The Radiation Protection Bureau of Health Canada conducted a dental X-ray survey during the winter 1999-2000. The purpose was to obtain information on the present state of dental radiology, patient radiation exposure and the performance of dental X-ray procedures and equipment (intra-oral, cephalometric and panoramic units as well as the processors). Letters requesting voluntary participation in the survey and a short questionnaire to obtain preliminary details (e.g. type of practice, radiation safety procedures established by the clinic, type of films used, workload and number of units) were sent to randomly selected clinics in the Ottawa Region. Upon receiving a positive answer, an inspection team made arrangements to visit the facility. The Inspection consisted of measuring entrance skin dose (ESD), half-value layer (HVL), tube voltage, irradiation time and field size of dental X-ray units. Darkroom fog, processing speed, developer temperature and development time measurements were performed on the processors. An intra-oral phantom was used to measure the film resolution and the optical density of low contrast objects under the facility's standard technique for an adult intraoral examination of the first upper molar. It generally took 15 minutes per unit or processor to perform the measurements. Results from more than 200 intra-oral units, 60 processors and a few panoramic and cephalometric units are presented.