Biomedical Imaging

Fig. 5.30: Illustration of the effect of fractionation on the survival of tumor and normal tissue cells with typical LQ parameters (tumor: α = 0.35 Gy−1, β = 0.035 Gy−2; normal tissue: α = 0.15 Gy−1, β = 0.05 Gy−2). A total dose D = 15 Gy is given in a single, two or five fractions, between which complete repair of SSBs is assumed. The curves indicate that fractionation spares the late responding normal tissue compared to the tumor. However, also the total dose D required to eradicate all tumor cells increases.

$S\left(nd\right)={\left[S\left(d\right)\right]}^n=\exp \left[-nd\left(\alpha +\beta d\right)\right],\left(5.98\right)$

i.e., the initial part of the survival curves is repeated in every ...