Absorbed dose of sensitive organs in maxillofacial region by different radiographic techniques: Panoramic, Waters, Caldwell and cone-beam computed tomography

Due to increasing use of X-rays in diagnosis and treatment of diseases, this study aimed to measure and compares the absorbed dose in a number of sensitive organs of head and neck in different radiographic techniques.
Thermoluminescence dosimeter (TLD) and a male equivalent RANDO phantom were used to measure the absorbed dose in organs. The dosimeters were set in certain sites of phantom related to eye, parotid, thyroid gland, occipital area and temporomandibular joint (TMJ). Panoramic and Caldwell techniques with two different exposure conditions as well as Waters technique with three different exposure conditions were performed. Cone-beam computed tomography (CBCT) was applied in low and normal resolutions with different field of view (FOV), and the mean absorbed dose was calculated and compared by the dosimeters related to each of the organs.
The panoramic imaging technique revealed the lowest dose for the eyes, but interestingly higher doses for the parotid gland and the occipital area. In total, Waters and Caldwell imaging techniques indicated that the occipital area and the parotid gland absorbed a higher dose than other organs. In the majority of CBCT scans the parotid region received the highest dose. However, during sinus CBCT (both in low-dose and high-dose modes), the TMJ and eye areas absorbed the highest dose. Investigation of the use of thyroid shield on the absorbed dose in this organ in CBCT showed an average 22% reduction in dose.
In total, panoramic, Waters and Caldwell imaging techniques indicated that the occipital area and the parotid gland absorbed a higher dose than other organs. In the majority of CBCT scans, the parotid region received the highest dose.