Radiotherapy, also known as radiation therapy, is a common oncologic treatment modality utilizing ionizing radiation to control or eliminate malignant cells. Radiotherapy plays a role in primary curative treatment (eg. head and neck cancer), adjuvant therapy (e.g. reducing recurrence rate after local breast cancer surgery) and palliation of cancer symptoms (e.g. reducing pain from bone metastases). Radiotherapy may be used alone, or synergistically with chemotherapy or immunotherapy, e.g. "chemoradiotherapy" etc.
Radiotherapy is also, less commonly, used to treat non-malignant disease, e.g. Graves thyroiditis, keloid scarring, etc.
Terminology
Radiotherapy is commonly abbreviated to RT, RTx, DXT (deep x-ray therapy) and XRT (x-ray therapy) in medical records.
Techniques
Radiotherapy is customarily divided into three main categories:
- external beam radiotherapy (EBRT) where a medical linear accelerator (linac) directs ionizing radiation at the tumor from outside the body
- sealed source radiotherapy (brachytherapy) where a radiation source(s) is placed inside or next to the tissue requiring treatment
- unsealed source radiotherapy (systemic radioisotope therapy) where a radioisotope is delivered through infusion (e.g. Lu-177-DOTATATE for neuroendocrine tumors) or ingestion (e.g. I-131 for thyroid cancer)