Radiotherapy is the medical use of ionizing radiation, generally as part of cancer treatment to control malignant cells.

Radiotherapy is commonly applied to the cancerous tumor because of its ability to control cell growth. Ionizing radiation works by damaging the DNA of exposed tissue, furthermore, it is believed that cancerous cells may be more susceptible to death by this process as many have turned off their DNA repair machinery during the process of becoming cancerous. To spare normal tissues (such as skin and organs which radiation must pass through in order to treat the tumor), shaped radiation beams are aimed from several angles of exposure to intersect at the tumor, providing a much larger absorbed dose there than in the surrounding, healthy tissue. Besides the tumour itself, the radiation fields may also include the draining lymph nodes if they are clinically or radiologically involved with tumor, or if there is thought to be a risk of subclinical malignant spread. It is necessary to include a margin of normal tissue around the tumor to allow for uncertainties in daily set-up and internal tumor motion. These uncertainties can be caused by internal movement (for example, respiration and bladder filling) and movement of external skin marks relative to the tumor position.

Radiotherapy oncology is the medical specialty concerned with prescribing radiation, either with the intent to cure, for adjuvant therapy, as palliative treatment or as therapeutic treatment. It is also common to combine radiation therapy with surgery, chemotherapy, hormone therapy, immunotherapy or some mixture of the four. Most common cancer types can be treated with radiation therapy in some way. The treatment intent will depend on the tumor type, location, and stage, as well as the general health of the patient. Brachytherapy, in which a radiation source is placed inside or next to the area requiring treatment, is another form of radiation therapy that minimizes exposure to healthy tissue during procedures to treat cancers of the breast, prostate and other organs.

Radiotherapy research at the AMC
The Radiotherapy Department of the AMC works in partnership with other departments that treat cancer patients. In addition, our Department also comprises an experimental laboratory that is also part of the research group experimental oncology.
Clinically, the department is an important partner in the EORTC trials, trials CVKO, ESHO and self-designed trials such as national studies in prostate, bladder, cervix and oesophaguscarcinomas.

The clinical research is divided in oesophageal cancer (M.C.C.M. Hulshof), pancreatic cancer (G. van Tienhoven) and pelvic cancer (L.J.A. Stalpers).
The research in the field of clinical physics focuses on hyperthermia (H. Crezee), brachytherapy (B.R. Pieters) and adaptive radiotherapy (A.Bel).