Dose Distribution in Head and Neck form Dental Conebeam CT

Objectives: To study dose distribution and estimated dose in head and neck at critical organs form dental CBCT Methods:The 8"x10" X-ray port-films were used to insert in every sections of a head and neck phantom. CBCT device was set to expose the phantom with the protocals of 100 and 120 kVp and the FOV P-mode, I-mode and D-mode. The relationship between the density of films and the radiation absorbed dose was determined via a linear regression equation where the density and the dose at the same point. The 18 organ doses in head and neck region were estimated according to the equation. Results: The highest dose is found at the Right Parotid, Left Parotid and Centre Sublingual Gland respectively. While the low doses occur at Posterior, Left and Anterior of Calvarium. Protocol with the highest organ doses is the FOV P-mode at 120 kVp, while protocol with the lowest organ doses is the FOV D-mode at the maxillary molar position with 100 kVp. Parameters in different pattern are clarified as following: For the protocols using the same FOV, the protocol using 120 kVp shows the 5% higher doses distribution in compared with 100 kVp. Conclusions: It is found that the dose distribution in the FOV region is almost the same pattern for all protocols. The organs in the FOV region would receive high radiation dose, and decreasing as the FOV increases.