Comparison of the Absorbed Doses of Eyes, Thyroid and Parotid Glands in Dental Cone Beam Computed Tomography (CBCT) and Panoramic Examinations Using CRANEX® 3D

As the application of the cone beam computed tomography (CBCT) is increasing in dental radiology and the departments with this equipment are developing, it seems that the determination of absorbed dose and evaluation of ionizing radiation risk from CBCT is essential. In this study, the absorbed dose of eyes, thyroid and parotid glands were compared in both examinations of dental CBCT and panoramic with CRANEX® 3D machine.
For each patient, 5 thermoluminescence dosimeter (TLDs) were placed as a pair in the back of upper eyelids, a pair 2 cm ahead of small anterior ear cartilage and the last one in the middle of neck on a prominence. The average absorbed dose was calculated for comparison of absorbed doses of different organs in two examinations.
Findings: In panoramic examination, right eye with 0.020 ± 0.002 cGy and right parotid with 0.283 ± 0.053 cGy had the lowest and the highest mean absorbed doses, respectively. In CBCT examination, the highest and the lowest mean doses belonged to the right parotid (0.465 ± 0.078) and the left eye (0.0311 ± 0.004), respectively. Mean absorbed doses for eyes, parotid and thyroid in panoramic was 0.022 ± 0.002, 0.270 ± 0.051, 0.027 ± 0.002 and in CBCT 0.033 ± 0.005, 4.410 ± 0.740, 0.0389 ± 0.051, respectively. The absorbed doses show meaningful differences for all organs in two examinations (P 0.001 for all).
Because of the wider beam (cone beam) and higher exposure factors in CBCT, the absorbed doses in this examination are higher than those of panoramic examination (more than 10 times).