[Dose measurement and risk evaluation in intraoral periapical radiography]

To measure the absorbed dose and evaluate the radiation risk of patient from full mouth series intraoral dental radiography, we used the LiF thermoluminescent dosimeters (TLD-100 chips) to detect the radiation dose of patients and RT-HUMANOID phantom as well. We also used water phantom and extracted human teeth to simulate the oral cavity and measure the absorbed dose of tooth while the intraoral dental radiography was taken. The average absorbed dose of skin near the thyroid gland of patient is 72.2 mu Gy from full mouth series intraoral radiograph with 14 dental films (speed D) using Gendex Panelipse II X-ray machine (75-80kVp, 15mA, 0.25s, FSD = 34-36 cm) with neck shield protection, and the radiation risk of thyroid gland of stochastic effect is estimated to be 3.6 x 10(-8). We also calculated the effective atomic number of enamel and dentin for obtaining the conversion factor of tooth. Four sets of figures were drawn to express the absorbed dose in water phantom and tooth in some different exposure conditions.