Tumors survival fraction. Relationship between absorbed dose D corrected by the HEF and the tumor cell survival fraction (left axis) and metabolic ratio (right axis) calculated at week 7 post-therapy using the doubling time obtained by the global fit. For colors and symbols refer to Figure 2. The line corresponds to Equation 4 with the parameters α, k and DT minimizing Equation 2, excluding the four metastases with SF > 1, which proved their shorter DT (using the actual metastasis DT in Equation 3 should necessarily give SF ≤ 1). These four metastases were already considered as outliers from Figure 2. See animation of the fit in Additional file 1.