The use of radiation aims to destroy tumour tissue that cannot be removed surgically. Often, radiotherapy is combined with surgical and medicinal treatment.

Approximately one in two cancer patients, or some 10,000 people a year, receive radiotherapy at some point of their disease. Radiotherapy is usually given from outside the body with a radiotherapy device by accurately aiming the radiation to the tumour. In some treatments, the radiation source, in most cases radioactive material, is placed inside the body.

Cancer cells are usually more sensitive to radiation than normal cells. The treatment is often administered in several parts, e.g. over 5–7 weeks so that the normal tissue will have time to recover. A difficult challenge in radiotherapy is focusing the dose on the tumour so that minimum damage is caused to the healthy tissue surrounding the tumour.

Radiotherapy uses such high doses that they can cause radiation sickness or a burn on the skin to the patient. The dose per treatment occasion may be 2 gray (Gy) and a total of 50–70 Gy in all. In radiotherapy, radiation is focused on a very small area, but should the radiation target the entire body, a dose of over 1 Gy would cause radiation sickness and a dose of over 6 Gy would be fatal. The harmful effects of radiotherapy can be major, but they still outweigh not treating the patient, who would then die.

In radiotherapy, a very small group of people are exposed to very high radiation doses. Even though the aim is to focus the radiation on the tumour being treated as accurately as possible, the healthy tissue surrounding the tumour also absorbs part of the radiation. Should this “extraordinary” radiation dose be divided among all Finns, it would cause an annual dose of 0.6 mSv on average per Finn.

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