Measurement of dose in panoramic dental radiology

The National Radiological Protection Board (NRPB) has recommended the intro duction of dose-width product (DWP) for the measurement of patient dose in panoramic dental radiology and has proposed a reference level of 65 mGy mm for adult exposures. This paper describes a method for measuring DWP and do se-area product (DAP) using thermoluminescent dosemeters (TLDs). The techni que was used on 16 sets with a range of exposure settings. The mean value o f DWP was 14% higher than the mean value reported from a survey by the NRPB . This difference is most likely to be caused by systematic variations due to measurement method. The average DAP for a standard adult examination was shown to be 11.3 cGy cm(2). Data are presented so that the DAP can be deri ved from the exposure factors (tube current and operating potential) and be am area. Based on published data for effective dose, it is estimated that t he DAP to effective dose conversion factor is approximately 0.06 mSv(Gy cm( 2))(-1). The average DAP value (11.3 cGy cm(2)) can be compared with the av erage value for intraoral radiography (9.3 cGy cm(2)) based on the NRPB sur vey of entrance surface doses assuming 6 cm circular collimation.