Proton beam radiosurgery

What is Proton beam radiosurgery?

Proton beam radiosurgery meaning Protons, may also be used in radiosurgery in a procedure called Proton Beam Therapy (PBT) or simply proton therapy. Protons are produced by a medical synchrotron or cyclotron, extracting them from proton donor materials and accelerating them in successive travels through a circular, evacuated conduit or cavity, using powerful magnets, until they reach sufficient energy (usually about 200 MeV) to enable them to approximately traverse a human body, then stop. They are then released toward the irradiation target which is region in the patient's body. In some machines, which deliver only a certain energy of protons, a custom mask made of plastic will be interposed between the initial beam and the patient, in order to adjust the beam energy for a proper amount of penetration. Because of the Bragg Peak effect, proton therapy has advantages over other the other forms of radiation, since most of the proton's energy is deposited within a limited distance, so tissue beyond this range (and to some extent also tissue inside this range) is spared from the effects of radiation. This property of protons, which has been called the "depth charge effect" allows for conformal dose distributions to be created around even very irregularly shaped targets, and for higher doses to targets surrounded or backstopped by radiation-sensitive structures such as the optic chiasm or brainstem. In recent years, however, "intensity modulated" techniques have allowed for similar conformities to be attained using linear accelerator radiosurgery.This procedure is used to treat tumors at the base of the skull and tumors of unusual shape.


reference: national Cancer Institute – Glossary for Registrars

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