Causes of excessive bitewing exposure - Results of a survey regarding radiographic equipment in New York

Objective. The purpose of this study was to identify the causes of excessiv e exposure in those dental practices that were found to use exceptionably h igh levels of radiation in bitewing radiography. Study design. Using the parameters of the Dental Exposure Normalization Tec hnique survey, certified radiation equipment safety officers conducted on-s ite inspections of 186 intraoral x-ray machines in 77 dental facilities. Results. In 23 facilities, the safety officers identified 43 units (23.1%) that delivered entrance exposures greater than 10% in excess of the upper l imit of recommended exposures. For each of 27 (63%) of these units, the cau se of the elevated exposure was clearly identifiable. Conclusions. The factors contributing to increased exposure, listed from mo st frequent to least frequent, were as follows: improper processing, kilovo ltage miscalibration, use of D-speed techniques with E-speed film, use of n ewly installed units with default timer settings that were too high, exposu re timer failure, and insufficient half-value layer. Only 18% of the facili ties surveyed reported using E-speed film.