Figure 3From: Feasibility and accuracy of relative electron density determined by virtual monochromatic CT value subtraction at two different energies using the gemstone spectral imagingThe error in the two different energy virtual monochromatic images subtraction algorithm relative to the nominal RED value over short and long term-period. Error bars present one standard deviation obtained from five sets of measurements at (a) 2 hours (short-term) and (b) 1-week intervals (long-term).Back to article page