Dose in the thyroid gland in tomography exports dental with conical beam

The main objective of this study was to evaluate the dose values to the thyroid gland with the use of shielded and unshielded in cone beam dental computed tomography. Measurements were made on a cone beam dental scanner from the manufacturer: Sirona; model: Orthophos XG-5-3D. This scanner It uses pulsed beam (standard / HD-OFF mode) and continuous beam (HD-ON mode), with a rotation angle of 180º. In this scanner an anthropomorphic mannequin with thermo-luminescent crystals inserted in tissues and organs of the head region were irradiated with and without thyroid protector. The parameters of acquisition were: 85 kV / 35.7 mAs / 0.3 mm Cu (HD-OFF) and 85 kV / 85.3 mAs / 0.3 mm Cu (HD ON). In both, the size of the field of view was: 8.0 cm in diameter x 8.0 cm in height. The results dosimetry shows us that even in these cases of a scanner with a rotation angle of 180º, where the The beam never goes through the front of the head. The use of the protector is very important. The reduction minimum in the value of the effective dose was 37% and the maximum differences in the value of dose in the thyroid gland were 10.7 microGray with the use of protector against 54.1 microGray without protector. In this way it can be concluded that even for scanners that the beam does not pass through the region anterior of the head, it is important to use the thyroid protector to reduce the dose to the gland and consequent reduction in effective dose.