Low-dose protocol of the spiral CT in orthodontics: comparative evaluation of entrance skin dose with traditional X-ray techniques

Background: The aim of this study was to evaluate the amount of radiation doses absorbed by soft tissues(entrance skin dose) with a low-dose spiral computed tomography (CT) protocol compared to conventional X-raytechniques commonly used in orthodontics.Methods: The amount of skin dose has been evaluated using a tissue-equivalent head-neck radiotherapy humanoidphantom with thermoluminescent dosimeters placed at the level of eye lens, parotid glands, and thyroid glands.CT images have been taken using a Sensation 16 Siemens CT scan and a low-dose protocol (15 mAs, 1 pitch, 2.5 mGy(CTDIvol), 80 kV, 1-mm slice thickness).Results: The difference in image quality between traditional X-ray techniques and low-dose spiral CT was statisticallysignificant (P < 0.05). The difference in mean absorbed dose instead was not statistically significant.Conclusions: Our protocol allows a more accurate orthodontic diagnosis without an increase of radiological risk forthe patients in comparison to traditional X-ray techniques