[Estimating organ doses of dental students in dental radiographic exercises]

To estimate doses absorbed in organs of dental students in the exercises of dental radiography, we measured the average organ doses of the dental radiographic examinations and sent out questionnaires about the radiographic exposure of the dental students. We selected five organs in the head and neck regions: lens of the eye, parotid gland, submaxillary gland, thyroid and pituitary fossa. The dose determinations were made for the full mouth intra-oral radiography with 10 films, and panoramic radiography and cephalometric radiography. Doses for all organs, except for the parotid gland, were widely distributed with one peak. The highest average dose per dental student was about 5000 microGy for the parotid gland, about 2900 microGy for the submaxillary gland, about 900 microGy for the lens of the eye, about 480 microGy for the thyroid and about 140 microGy for the pituitary fossa. Dose limits for dental students in such exercises have not been yet established. But the organ doses, especially for the parotid gland, appear very high. To reduce exposure in the exercises and to protect the dental students from excess exposure, we need to reconsider the study of dental radiographic techniques.