of the reconstructions increases only marginally when $\beta$ is increased. However, the pixel error percentage drops considerably as the number of ARM iterations during an MC-DART iteration increases. Also, when scanning data from many angles is available the reconstruction quality improvement with multiple materials become much better. For only $2$ angles, the reconstruction between $C=1$ and $C=10$ channels improves from pixel error percentage $27\%$ to $23\%$ for two materials and from $55\%$ to $41\%$ for ten materials. In comparison, for as much as $128$ angles the reconstructions between $C=1$ and $C=10$ channels improve by from $3\%$ to less than $1\%$ for two materials and from $46\%$ to $4\%$ for ten materials. We conclude that in all these cases the MC-DART algorithm gives better results when more channels are available.\

[0.4]{} ![Convergence behavior for material classes with $C=10$ channels. (a) Phantom that has been used with $m=4$ materials (b) Graph showing the behavior for each material class in a DART routine for this phantom. The number of iterations for the initial reconstruction is set to $2$, the number of DART iterations is $10$, the number of ARM iterations is set to $10$, the number of angles is $8$, fixing probability is 