Measurement of radiation dose and analysis of dose distribution in the thyroid and eye lens during digital panoramic tomography

This study investigates the radiation dose and its distribution in critical organs of the human head during the use of digital panoramic radiography devices. The aim was to quantify the doses accumulated in the thyroid and eye lenses, as well as to analyse the overall dose distribution across a selection of modern panoramic units. A female Alderson-Rando phantom, equipped with 3D-printed slabs and drilled holes for placing an ionisation chamber, was repeatedly exposed in four digital panoramic devices (Orthophos XG Plus, ProMax 2D Classic, Viso G7, and Veraview X800). Measurements were taken in both the orbital regions and the thyroid. Additionally, five radiochromic films were placed between the phantom slabs, from the orbital floor to the thyroid region, to assess dose distribution. Equivalent doses for the thyroid ranged between 0.30 µSv and 1.46 µSv, while the doses for the eye ranged from 0.88 µSv to 4.24 µSv. There were significant differences between the devices (pFriedman < 0.001). The dose distribution in the anterior part followed the typical trajectory of the rotational isocenter of the fan beam. The distribution varied across devices, with the highest peak observed in the vertical region of the external acoustic meatus. The absorbed doses to the thyroid and eye lenses in digital panoramic devices are generally low (in the microsievert range), and dose distribution varies between devices.