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Radiation therapy or radiotherapy (RT, RTx, or XRT) is a treatment using ionizing radiation, generally provided as part of cancer therapy to either kill or control the growth of malignant cells. It is normally delivered by a linear particle accelerator .
Radiotherapy beams are classified by the particle they are intended to deliver, such as photons (as x-rays or gamma rays), electrons, and heavy ions; x-rays and electron beams are by far the most widely used sources for external beam radiotherapy. Orthovoltage ("superficial") X-rays are used for treating skin cancer and superficial structures.
Megavolt X-ray (or photon) therapy, which delivered a beam of 25 MeV X-ray photons. The X-ray photons are produced by colliding a high current, narrow beam of electrons with a tungsten target. The X-rays are then passed through a flattening filter, and then measured using an X-ray ion chamber. The flattening filter resembles an inverted ice ...
Due to the higher ionization density caused by soft X-ray radiation in the tissue, the relative biological effectiveness (RBE) of low-energy X-rays on tumor cells is higher when compared to high-energy X-rays or gamma rays which are delivered by linear accelerators. [15]
Doctor reviewing a radiation treatment plan. In radiotherapy, radiation treatment planning (RTP) is the process in which a team consisting of radiation oncologists, radiation therapist, medical physicists and medical dosimetrists plan the appropriate external beam radiotherapy or internal brachytherapy treatment technique for a patient with cancer.
Cobalt therapy is the medical use of gamma rays from the radioisotope cobalt-60 to treat conditions such as cancer. Beginning in the 1950s, cobalt-60 was widely used in external beam radiotherapy (teletherapy) machines, which produced a beam of gamma rays which was directed into the patient's body to kill tumor tissue.
Unlike electrons or X-rays, the dose from protons to tissue is maximum just over the last few millimeters of the particle's range. Particle therapy works by aiming energetic ionizing particles at the target tumor. [4] [5] These particles damage the DNA of tissue cells, ultimately causing their death. Because of their reduced ability to repair ...
Tomotherapy treatment times can be as low as 6.5 minutes for common prostate treatment, [7] excluding extra time for imaging. Modern tomotherapy and conventional linac systems incorporate one or both of megavoltage X-ray or kilovoltage X-ray imaging systems, enabling image-guided radiation therapy (IGRT). In tomotherapy, images are acquired in ...