Digital intraoral imaging: analysis of retakes and reduction in radiation exposure using rectangular collimation

The purposes of this study were to examine the distribution and extent of retakes with digital intraoral imaging when operators transitioned from using round to rectangular collimators and to determine the effect of collimator shape on radiation exposure to patients. This study was conducted using digital intraoral radiographic data from 2018 to 2019 in a dental school radiology clinic. Digital intraoral radiography was performed with round collimators during 2018 and then with rectangular collimators in 2019 with the same cohort of students. Exposure values were obtained, and effective doses were calculated. Although the number of retakes increased with the transition from round to rectangular collimators, the transition also resulted in a statistically significant reduction in the overall effective dose for patients (P < 0.01; Pearson chi-square test), with an average difference of 60% between round and rectangular collimators. Even with the increase in the number of retakes, a decrease in effective dose was observed when rectangular collimation was used. Most retakes were due to placement errors, defined as missing contact points, missing apices of teeth, or a missing area of interest. As students gained more experience and practice with rectangular collimation, the number of retakes decreased. With proper clinical and didactic training and emphasis on the importance of rectangular collimation, a transition from round to rectangular collimation can be achieved with a minimal initial increase in retakes and subsequent normalization of rates, resulting in a significant reduction of the radiation dose to patients.