Film cassette for quality assurance of dental X-ray tubes

Abstract

The guidance notes for the protection of patients against ionizing radiations arising from medical and dental use specify that dental X-ray installations should be surveyed at least once every 3 years (HMSO, 1988). X-ray equipment in Community Dental Clinics, for whom we provide a radiological protection service, is not routinely serviced by the manufacturer. We felt it would be desirable to monitor the performance of the X-ray equipment at more frequent intervals as faults may go undetected leaving the equipment radiologically unsafe. We have developed a film cassette (Fig. 1) to enable routine quality assurance checks of equipment to be made by dental staff without the use of an ion chamber. The film is sent to the Physics Department for processing and densitometric analysis. The cassette is used to measure kilovoltage, half value layer (HVL), tube output and beam diameter at the patient end of the cone.