Figure 2.

(a) Determination of the standard error on the mean HU, $\mathrm{\Delta }H{U}_{\text{meas}}$. of the Gammex bone (CB2 $‐30\hspace{0.17em}\mathrm{\%}{\text{CaCO}}_3$) plug for an ROI of $20\hspace{0.17em}\text{pixels}\times 20\hspace{0.17em}\text{pixels}$, and (b) variation of this error with the size of the ROI for this and for four of the other plugs, listed in order of descending HU.