The majority of cancer patients have many forms of treatment, such surgery to remove a tumour, followed by radiation and/or systemic therapy. A surgical oncologist (or maybe another sort of specialist termed an interventional oncologist) would perform the operation, and a clinical or medical oncologist and their team would organise and administer the other therapies. Although only clinical oncologists are qualified to provide radiation, both medical oncologists and clinical oncologists provide non-surgical cancer treatment. To accurately target and eliminate tumours, radiotherapy employs the radiation energy from artificially produced particles and radioactive elements. The term "radiation" often refers to "external beam" radiotherapy, which involves treating patients by beaming X-rays into their bodies. Linear accelerators are most frequently used to produce these X-rays (LINAC). Proton beam treatment, a more recent form of external beam radiation that employs proton particles rather than X-rays and has begun to be used in the UK for patients with very certain malignancies. Internal radiation known as "brachytherapy" involves injecting radioactive substances known as radioisotopes into a patient to destroy cancer cells. Using radioiodine to treat thyroid cancer and iridium to treat cervical cancer are two examples. Chemotherapy, which prevents cancer cells from proliferating, hormone treatment, which reduces hormones that might promote cancer growth, and immunotherapy, which prepares the body's immune system to combat cancer are examples of systemic therapies.