Summary: The National Radiation Protection Institute (NRPI) developed a method for independent postal quality audit of dental Intraoral X-ray units. Its aim is to make more effective and to complement the existing system of quality assurance in dental radiodiagnostics particularly considering the radiation safety of patients that arises from valid Czech laws. The present paper gives information of this method and prepared changes in the quality assurance system. The postal audit means that a dentist using an X-ray intraoral unit obtains by post a simple dosimetric set containing an instruction sheet. The dentist is requested to do all required procedures according to the instruction sheet and to send the set back to NRPI. The measurements cover only the basic and most important parameters of the X-ray unit, which can influence the radiation safety of the patient. Specifically, air kerma output measurements, radiation f"ield size and exposure reproducibility. The film developing proces is checked by measurements of sensitometric parameters. The method was tested at 49 medical workplaces equipped with an X-ray unit. The performed pilot study proved applicability of the method in form of a postal audit and besides fit proved its ability to judge the radiation protection level at a particular medical workplace. The results of evaluation support the known fact that the main problems in current dental radiodiagnostics in the Czech Republic are outdated X-ray units and application of improper methods for dental film processing. The method has been implemented finto the existing system of controls since 2002. It is assumed that one half of all Czech X-ray units will be controlled in this way every year performed on state costs. Medical workplaces with good results of the audit will not be required to have tests for a period of one year then.

        Key words: postal audit - intraoral X-rays - dental radiodiagnostics