The Influence of reduced Bit-Depth on The Accuracy of Linear Measurements of Cone Beam Computed Tomography. Diagnostic Accuracy Study.

Dalia Ali Abou-Alnour, Wessam Magdy Youssef


Objectives: This study aimed to assess the influence of reduced bit depth on CBCT linear measurements accuracy.

 Materials & Methods: This study was executed on six implant bone models. On each model surfaces, nine radio-opaque markers “gutta-percha pieces” were glued. CBCT radiographic examination of each bone model were performed. For real measurements, the distance between each two markers was measured using digital caliper. The resultant images were evaluated using Fiji software at 16 and 8 bit-depths.

Results: Intra and inter-observer reliability was more than 0.99. 8 and 16-bit images measurements showed statistically significant difference with (p value<0.05). 16-bit images measurements and caliber ones showed no statistically significant difference (p value>0.05) for Paired T and Wilcoxon tests. 8-bit images measurements and caliber ones showed statistically significant difference p value=0.001 for both Paired T and Wilcoxon tests. Mann-Whitney Test showed no significant difference between 16 bit and 8-bit depths regarding the absolute measurement error (AME) where p value>0.05.

Conclusion: This study concluded that 8-bit CBCT images could adversely affect the precision of the linear measurements but the statistical significance was not translated to the clinical relevance.


Measurement accuracy; Cone-beam CT; Fiji.

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