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

The current study was conducted on dry human skulls to evaluate the accuracy of CBCT linear measurements obtained by both standard and ULD protocols and to the compare the measurement error of 2D MPR and 3D VR images obtained by both protocols.Twenty-three anatomical landmarks were marked on each of the sixteen included skulls, gutta percha pieces were glued on the marked anatomical landmarks, and then fourteen linear measurements were taken between them using a digital caliper. These direct linear measurements were considered as the gold standard. The skulls included in the study were covered with twelve layers of pink modeling wax to simulate soft tissue attenuation, then were scanned using Planmeca Promax 3D Mid CBCT machine with two different scan protocols -the standard and ULD one-.The CBCT raw data was imported to a third party software (In Vivo 5), and the same fourteen linear measurements were taken on both 3D VR images and 2D MPR orthogonal images. Superimposition of both standard and ULD CBCT images was performed for standardization of measurements on the 2D MPR images

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