Influence of cone beam computed tomography settings on radiation dose and image quality / Noha Sherif Gabr Ibrahim ; Supervised Mushira M. Dahaba , Ahmad Mohamad Abdalsamad , Nader Abdelsalam Elsherbini

Thesis (M.Sc.) - Cairo University - Faculty of Oral and Dental Medicine - Department of Oral (Radiology)

To assess the effect of various setting parameters on radiation dose and image quality during cone beam CT imaging of the jaws. A RANDO phantom loaded with thermoluminescent dosimeters (TLDs) in sensitive organ sites was scanned with different dental protocols using a planmeca proMax 3D CBCT machine by using different mA (10, 12 and 14), kVp (70, 80 and 90), and resolution settings (200 æm and 100 æm). Average tissue absorbed dose, equivalent dose, and effective dose were calculated. The variables consisted of Effective doses were derived using ICRP2007 recommendations. CBCT images were then analyzed to evaluate image quality by two experienced oral and maxillofacial radiologists. The total effective dose decreases by 27.3% upon changing kVp from 90 to 80 and decreases by 46.8% upon decreasing it from 90 to 70. Regarding mA, the results demonstrated that the total effective dose decreased by 20.9% when mA was decreased from 14 mA to 12 mA, and decreased by 33.8% upon changing the mA from 14 to 10 mA. Considering the effect of different voxel sizes on total effective dose, our study showed that there was no statistically significant difference in the radiation dose between normal and high resolutions. Regarding image quality, our results showed that there was no statistically significant difference in the image quality between different mA, kVp and voxel sizes. Reduction in radiation dose can be achieved by using lower kVp and mA settings with no significant effect on the image quality. Voxel size had no significant effect, neither on radiation dose nor on image quality

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