Evaluation of trabecular bone microstructure and cortical morphology using cone-beam and micro-CT images: impact of tube voltage setting.

Objective: To evaluate the effect of various tube voltage (kV) settings on the accuracy of cone-beam computed tomography (CBCT) images in measuring trabecular microstructure and cortical morphology, using micro-CT (μCT) as the reference.

Methods: Ten bone samples of sheep mandibles were scanned using both μCT and CBCT at three different tube voltage settings (80, 85, and 90 kV). Identical regions of interest (ROIs) on trabecular and cortical bones were analyzed in all images. Measurements of trabecular microstructure included bone volume fraction (BV/TV), trabecular thickness (Tb.Th) and space (Tb.Sp), while thickness (Ct.Th) and area (Ct.Ar) of cortical bone were measured to determine cortical morphology. Measurements were compared using paired t-test, while agreement between measurements of two modalities was assessed using Bland-Altman analysis. One-way ANOVA was used to determine differences in measurements of CBCT images at different kVs (p < 0.01).

Results: Compared to μCT, CBCT overestimated trabecular parameters and Ct.Th but underestimated Ct.Ar, with high agreement observed between the methods. Significant differences were found for all measurements except BV/TV and Ct.Ar at all kVs. No differences were observed between CBCT measurements at different tube potentials.

Conclusion: The tube voltage of CBCT has minimal impact on the measurement accuracy of most microstructural parameters. BV/TV and Ct.Ar measurements may be particularly preferred for bone evaluations using CBCT images.