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

Aim To assess the accuracy of linear measurement obtained from CBCT images in 3D volumetric rendering and multiplanar slices with different voxel sizes. Methodology: 9 mandibles with twelve radio opaque markers fixed on each one were imaged using CRANEX® 3D (Soredex Oy, Tuusula, Finland) CBCT machine. Each mandible was imaged twice with voxel sizes 250 om and 350 om. 2D and 3D linear measurements obtained from the CBCT software were compared to the real physical measurements taken by a digital caliper. Software measurements were recorded twice by the principal investigator and once by the supervising professor. Intra- and inter-observer agreements were assessed using Intra-Class Correlation Coefficient (ICC). SPSS®IBM Version 24 and MedCalc® version 12.1 for Windows were used for statistical analysis. Results: CBCT 2D measurements with voxel sizes of 250o and 350o showed a mean difference= 0 mm both with 95% of difference being -0.6 mm above or 0.7mm below and-0.5 mm above or 0.6 mm below the Gold Standard respectively. CBCT 3D measurements with voxel sizes of 250o and 350o showed a mean difference= 0 mm both with 95% of difference being -0.5 mm below or 0.5 mm above and -0.6 mm above or 0.7 mm below the Gold Standard. Intra-observer and inter-observer reliability regarding all measurements showed excellent agreement. Conclusions: 2D and 3D measurements driven from CBCT images with voxel size of 350 o are accurate as measurements driven from CBCT images with voxel size of 250 o with less radiation delivered to the patient. 3D measurements driven from CBCT are as accurate as 2D measurements. 2D and 3D CBCT measurements driven from CBCT are reliable

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