**3.4 Calculation of EQD2 taking into account the interruption in RT course**

Irradiation of tumors of the head and neck. The maximum dose to the spinal cord is 45 Gy. Dose on the main target is 70 Gy. Due to reactions after fraction 25, the patient was placed on a two-week break. EQD2 is to be calculated.

The data from the condition of the problem are entered, the situation of a twoweek break is simulated, and the answer of 59.5 Gy is obtained (**Figure 7**).


#### **Figure 7.**

*Сalculation of EQD2 taking into account the interruption in RT course.*
