Method: A head anthropomorphic phantom was used with nanoDOT optically stimulated luminescence (OSL) dosimeters (Landauer Corp., Glenwood, IL) attached to various anatomic landmarks of selected radiosensitive tissues of interest. The phantom was scanned under various modes of operation and scan protocols for typical orthodontic exams on three dental CBCT systems plus a conventional dental x-ray imaging system. The nanoDOT dosimeters were calibrated for each of the head phantom scan protocols, and specifically for each of the imaging systems. Peak skin dose and surface doses at the eye lens, thyroid, submandibular and parotid gland levels were measured.
Result: The measured skin doses ranged from 0.09 to 4.62 mGy depending on dosimeter positions and imaging systems. The surface doses to the locations of the eyes were ~4.0mGy, well below the threshold for possibly causing cataract development (500mGy). The results changed accordingly with x-ray tube output (mAs and kV) and also were sensitive to scan field of view (SFOV). As compared to the conventional dental x-ray imaging system operated in panoramic and cephalometric modes, doses from all three CBCT systems were at least an order of magnitude higher.
Conclusion: Maximum peak skin dose and surface doses at the eye lens, thyroid, and salivary gland levels are low to induce deterministic effects. However, conventional radiographs are dose sparing compared to any operational mode of a dental CBCT scanner from a radiation-conscious point of view.