External radiation treatment is one of the treatment methods against breast cancer. Utmost goal during the treatment with radiation is to maximize the benefit for the patient while sparing other vital organs from radiation that could lead to organ's toxicity. The assessment of the overall benefit of a radiation treatment can be modelled with the help of linear quadratic model. That model simulates the cell killing for a specific type of cell under a given radiation prescription and schema. With the help of modelling, oncologists and medical physicists can simulate and predict the outcome of a radiation treatment schema.