Kiiritusterapia

Kiiritusterapia, known in English as radiation therapy or radiotherapy, is a medical treatment that uses ionizing radiation to control or kill malignant cells and to relieve symptoms in certain benign conditions. It can be delivered externally (external beam radiotherapy, EBRT) with linear accelerators, or internally (brachytherapy) by placing radioactive sources near or inside the tumor.

More recently, advanced techniques such as intensity-modulated radiotherapy (IMRT), image-guided radiotherapy (IGRT), stereotactic radiotherapy and radiosurgery are used to shape and precisely target doses. These methods aim to maximize the dose to the target while minimizing exposure to surrounding healthy tissue.

Planning is based on imaging studies (CT, MRI, PET) to define the gross tumor volume and margins, followed by calculation of the prescribed dose distributed in fractions over several days or weeks. Treatment regimens vary by cancer type, stage, and goals (curative or palliative).

Common acute side effects include fatigue, skin changes, and localized irritation; late effects can involve tissue fibrosis, organ dysfunction, or secondary cancers, depending on dose and area treated. The specific side effects depend on the treated region and the overall treatment plan.

The aim is to maximize tumor control while minimizing harm to normal tissue. Safety requires a multidisciplinary team of radiation oncologists, medical physicists, dosimetrists, and radiation therapists, along with shielding and monitoring procedures to protect patients and staff.

Historical notes: radiotherapy emerged in the late 19th and early 20th centuries after the discovery of X-rays; it evolved into a central cancer treatment by mid- to late-20th century and continues with ongoing technological advances. In Finnish medical usage, Kiiritusterapia is the term used to describe this modality.