Dosimetry of organ at risks in Orthopantomography

Orthopantomography is a common imaging technique of the jaw. Although in compare to other diagnostic radiology methods, the dose of radiation received by the patient is relatively low in orthopantomography, still is remained as the most common method in diagnostic radiology. Therefore, because of the commonalty of this method, it seemed rational to estimate the dose received by the Organ At Risks (OARs). This study has been designed to determine the surface dose received by the eyes, parotids, thyroid and submandibular salivary glands using Gafchromic films in 20 patients referred to imaging centers (digital and analog). To increase the repeatability of the technique, each measurement was triplicated and the results were presented as mean (SD). The mean measured surface dose received by the submandibular glands (left, right and center), thyroid (left and right), parotid (left and right) and eye (left and right) for the digital system were 4.17, 4.65, 5.08 and 4.74 and for the analog system were 10.33, 10.12, 10.28 and 10.73, respectively. This study showed no difference in surface dose received by the left and right eyes, left and right thyroid, left and right parotid, left, right and center submandibular glands in any of the digital or analog systems studied (P ≤0.05). In addition, the surface dose received by the selected organs in digital system was significantly lower than that by the analog system (P ≤0.05).