Fig. 8
Risk-adjusted, restricted cubic splines with 4 knots of crack depths measured by contrast-enhanced CBCT and crack depths measured by micro-CT. The X axis shows the crack depths measured using contrast-enhanced CBCT; the Y axis shows the crack depths measured using micro-CT. Red line represents crack depths measured using micro-CT; Grey area represents a 95% confident interval. The root mean square error (RMSE) was 1.813, R2 was 0.724, P = 0.000. Micro-CT: micro-computed tomography; contrast-enhanced CBCT: contrast-enhanced cone beam computed tomography