RADIATION-DOSE AS A FACTOR IN THE CHOICE OF ROUTINE PREOPERATIVE DENTAL RADIOGRAPHS

Radiation doses received by patients during dental x-ray examinations were measured in 95 patients referred to the X-ray Department of the T eaching Dental Hospital, University of Nairobi. The mean skin dose for single periapical films was 5.% milligray (596 millirads) with the bi tewing view recording a mean dose of 5.57 milligray (mGy). During a 14 -film full-mouth periapical survey, mean doses ranged from 10.3-16.2 m Gy for the upper jaw and 10.1-13.5 mGy for the lower jaw, respectively , depending on the region of dentition. In these full-mouth examinatio ns, the distribution of skin dose over different parts of the dentitio n showed a characteristic pattern which may be explained by the overla p of radiation fields in the aggregated series of exposure. Orthopanto mography recorded lower mean skin doses of 3.26 mGy in the molar regio n and 2.67 mGy at the posterior midline at the level of the 2nd cervic al vertebra. The relative merits of intra-oral radiography versus orth opantomography are discussed, with radiation dosage as one of the fact ors to be considered. Some observations are made on measures to reduce patient dose.