Abstract:
Currently, there are many cone beam computed tomography (CBCT) devices with various field of views (FOVs). Thus the selection of proper FOVs and number of scans should be considered based on clinical applications and ALARA principle. The purpose of this study is to study the effect on number of scans and field of views such as large, medium and multi-small, on the radiation dose from CBCT systems in phantom study.
Radiation dose from 3 CBCT devices were recorded by using RANDO phantom. For 3D Accuitomo170, C_vol (mGy), DLP (mGy.cm) and the effective dose (E:µSv) were determined. For Kodak devices, DAP (mGy.cm^2) was recorded. In two or three scans of small FOV, E and DAP were obtained.
Inaccuracy in C_vol verification is obtained when FOVs are less than 16cm (PMMA phantom diameter). For 3D Accuitomo 170, the radiation dose reported in C_vol (mGy), DLP (mGy.cm) and E (µSv) of FOV 17x5 and 17x12cm^2 were 7.7, 38.5, 88.55 and 6.4, 76.8, 176.64 respectively. For Kodak9000 3D and Kodak9500 CB 3D, FOV 5x3.7cm^2, 9.3x5x3.7cm^3, 9.3x7.4x3.7cm^3, 15x9cm^2 and 20.6x18cm^2, DAP values were 131, 261, 392, 211 and 502 mGy.cm^2 respectively. Two and three scans of FOV 5x3.7cm^2 were 262 and 393 mGy.cm^2 respectively. In conclusion, the radiation dose is higher when the FOVs and number of scans increase.
