Figure 1.

Cell survival and tumor control probability (TCP) curves of external beam radiotherapy (EBRT) vs. targeted radionuclide therapy (TRT), including the comparison between alpha and beta radiation as well as homogeneous vs. heterogeneous dose; while EBRT has a linear-quadratic survival curve, the one of TRT is more linear. Alpha particles are more effective compared to EBRT, while beta particles are less effective. The TCP curves show that the heterogeneous dose distributions decreases the efficacy. Most of the input data are taken from Bernhardt et al., who simulated a metastatic control probability model for prostate cancer [9] ($T_{eff}=51$ h, $T_r=1.9$ h, $\alpha /\beta =1.5$ Gy, $\alpha =0.147$ Gy${}^{-1}$ and $N=1.79\times {10}^8$), combined with the relative biological effectiveness (RBE) values of 1.5 and 14 for ${}^{177}$Lu and ${}^{241}$Am, respectively, for the prostate cancer cell line PC3 [10]. For the dose heterogeneity, a lognormal dose distribution with shape parameter ${\sigma }_D=0.1$ was assumed.