Figure A11.

The outer radius $R_{\mathrm{spheroid}}$ of the RS model agrees with the analytical predictions. We used the parameter fitted for the FaDu cell line and a radiation dose of 20 Gy. Certain parameters were altered to make the characteristics of the spheroid dynamics more pronounced: the initial volume is lower and the probability for a mitotic catastrophe $P_{\mathrm{mc}}$ changes after $t=25$ d from $P_{\mathrm{mc}}^1=0$ to $P_{\mathrm{mc}}^2=0.87$. From the analytical derivation, a linear scaling (black dashed lines) for larger and an exponential scaling (black dotted lines) for smaller radii is expected; (a,b) display the same results in the linear and semi-log-y scales, respectively. The gray area marks the predicted transition region between the linear and exponential regimes $dr\le R_{\mathrm{spheroid}}\le 3·dr$.