|External beam radiotherapy (EBRT) is the most common form of radiotherapy. The patient lies on a couch and an external source of radiation is pointed at a particular part of the body. Beams are generated outside the patient and are targeted at the tumor site. These high energy x-rays can deposit their dose to the area of the tumor to destroy the cancer cells and, with careful treatment planning, spare the surrounding normal tissues.
Image-guided radiation therapy (IGRT: KV, CBCT) is the process of frequent two and three-dimensional imaging, during a course of radiation treatment, used to direct radiation therapy utilizing the imaging coordinates of the actual radiation treatment plan. The patient is localized in the treatment room in the same position as planned from the reference imaging dataset.