Gaps of radiotherapy treatment are one of the factors recognized as unfavorable in terms of tumor control and disease prognosis. All strategies for compensating the negative effect of radiotherapy treatment gaps are based on radiobiological models. Using the modified square linear formalism (Dale`s equation) it is possible to calculate the additional dose in order to compensate the accelerated tumor repopulation effect. SARS-CoV-2 infection is an important factor that can lead to an interruption of irradiation for medium and long- term intervals. We aim to present the radiobiological data underlying the recalculation of radiotherapy treatment and exemplification for different clinical scenarios in the case of head and neck cancers (Ref. 17). Keywords: adiobiology, treatment gaps, locally advanced head and neck cancers, radical radiotherapy, COVID-19 pandemic.