# TDF Plan: Tumor Repopulation

A correction for tumor repopulation may be added to the calculation. To include this correction factor click the "Include Repopulation" checkbox in the Biology group. Enabling generic repopulation is the simplest approach. The tissue library contains predefined settings for slow, intermediate and rapid repopulation. If you choose not to use the generic repopulation method then new terms are added to the LQ model so that the equation for biological effectiveness becomes: E/α = n × d × (1 + (d / (α/β))) - ((0.693 / α) × (t / Tpot)) where t = time (days), Tpot = the potential doubling time of the tumor, and α = initial slope of cell survival curve. There is little data regarding what values to use for α and Tpot, so using this factor is speculative at best. The parameters for repopulation and LDR calculations are accessed by clicking the repopulation "Settings" buttons.

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