An Estimate of Radiation Dose to the Lens of the Eyes, Parotid Gland, and Thyroid Gland in Dental Panoramic Radiography

Dental panoramic radiography (DPR) is one of the most frequent diagnostic X-ray procedures, the application of which is currently on a growing trend. During DPR, several radiosensitive tissues, such as the lens of the eyes, parotid gland, and thyroid gland, contribute to the radiation field, and it is necessary to monitor their received dose. The aim of this study was to evaluate the radiation dose to the lens of the eyes, parotid gland, and thyroid gland in patients undergoing DPR at Lorestan Province, Western Iran.
This cross-sectional study was performed on 180 patients of both genders referred to DPR at two most crowded hospitals in Khorramabad, Iran, namely Tamin-e Ejtemaei (TE) and Shohada-ye Ashayer (SA) hospitals. The radiation dose measurements were carried out using LiF (Mg, Cu, P) thermoluminescent dosimeters (TLDs). To measure the absorbed dose received by the lens of the eyes, parotid gland, and thyroid gland in each patient, five sets of three TLDs, wrapped in a thin plastic bag, were positioned over each eyelid and the anatomical position of the parotid and thyroid glands. The TLDs were read within 24 h of exposure.
The mean absorbed dose received by the lens of the eyes, parotid gland, and thyroid gland were obtained as 155, 160, and 72 µGy for the TE Hospital, respectively. These values were obtained as l24, 558, and 56 µGy, respectively, for the SA Hospital. The results revealed a statistically significant difference between the organs located outside and inside the primary beam in terms of the absorbed dose (P<0.001).
The absorbed dose received by the lens of the eyes and thyroid gland was generally lower than the values reported in similar studies. Nevertheless, the absorbed dose received by the parotid gland in the SA Hospital exceeded the recommended dose reference level of 400 µGy in DPR.