Thyroid shields for radiation dose reduction during cone beam computed tomography scanning for different oral and maxillofacial regions.

AIMS

To evaluate the radiation dose level during cone beam computed tomography (CBCT) scanning for the different oral and maxillofacial regions with and without thyroid collar shielding.

MATERIALS AND METHODS

Average tissue-absorbed dose for a DCT PRO CBCT was measured using thermoluminescent dosimeter chips in a phantom with or without applying thyroid collars. Effective organ dose and total effective dose were derived using International Commission on Radiological Protection (ICRP) 2007 recommendations.

RESULTS

The total effective doses for large, middle and small field of view (FOV) were 254.3 μSv, 249.0 μSv and 180.3 μSv, respectively, when no thyroid collar was used. Applying one thyroid collar around the front neck can reduce the total effective doses to 208.5 μSv (18.0% reduction), 149.1 μSv (40.1% reduction) and 110.5 μSv (38.7% reduction), respectively. When two thyroid collars were used around the front and back neck, the total effective doses were reduced to 219.1 μSv (13.8% reduction), 142.0 μSv (43.0% reduction) and 105.5 μSv (41.5% reduction), respectively.

CONCLUSIONS

Thyroid collar can reduce the radiation dose during CBCT scanning for the oral and maxillofacial regions. The dose reduction becomes more significant when middle or small FOV is chosen.