107 - Pediatric Phantom Dosimetry Evaluation of the Tru-Image® Rectangular Collimator

Purpose: The purpose of this study was to compare the effective dose (E) on a pediatric phantom when using the Tru-Image® rectangular collimator and universal round collimator for two bitewing radiographs (right and left).

Methods: Absorbed doses utilizing the Tru-Image® rectangular collimator and universal round collimator were acquired using an anthropomorphic 10-year-old child phantom and optical stimulated luminescent dosimetry with 24 dosimeters in each set. Each set of dosimeters was exposed to a right and left bitewing with manufacturer’s child settings. Fifty clinical exposures were completed for each set, and three sets were exposed for each type of collimator. Following exposure, the equivalent doses were calculated for various tissues within the head and neck region, and the effective doses were calculated utilizing the 2007 recommendations from the International Commission on Radiological Protection (ICRP).

Results: The overall E for the Tru-Image® rectangular collimator and universal round collimator, respectively, were 6.3 µSv and 25.3 µSv, and this difference was statistically significant (P < .001). The highest equivalent dose for both collimators was delivered to the oral mucosa. When compared to the universal round collimator, the Tru-Image® rectangular collimator had significant dose reduction at all locations (all P< .05). When normalized and adjusted to have the same source to end distance for each collimator, there was overall a 65% dose reduction with the rectangular collimator.

Conclusion: The average effective dose was significantly reduced with the use of the Tru-Image® rectangular collimator. Clinical use of this rectangular collimator should be considered in the pediatric population.