Unplanned gaps in radiotherapy can impact on its clinical effect, especially in tumors with accelerated repopulation. In the literature, several technical solutions have been proposed. According to the situation, compensation for the effect on the tumor to the detriment of normal tissue tolerance can be achieved. An approach, modulated according to the gap duration and timing is proposed aimed at constant tumor control with no significant increased risk of side-effects. The decisional algorithm and calculation formulae are used in our center in teaching addressed to residents to make them familiar with the possible clinical applications of radiobiological knowledge.