Radiation therapy, i.e. all techniques for treating cancer by irradiation, is used today for nearly one out of two patients. It is part of the therapeutic strategies to fight cancer, along with chemotherapy and surgery.
Radiation therapy is nowadays more and more associated with imaging techniques, which allow to direct the rays towards the targets to be treated. The therapies can be external or internal.
Radiation therapy is said to be external when the radiation source is located outside the patient. The vast majority of radiotherapy today are external, using X-rays (photons) or electrons. In some very special cases, where tumors are located near critical organs that are sensitive to radiation, it is also possible to use other types of radiation such as protons (proton therapy) or ions (hadrontherapy).
Radiotherapy uses the latest technological advances, both in terms of the machines used for irradiation and the computer software used to pre-calculate the patient's treatment. Several steps are necessary to achieve an optimal distribution of radiation in the tumour, while trying to spare the surrounding healthy tissue as much as possible.