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Research in this area has focused on the three most common sources of radiation used for these applications, including gamma, electron beam, and x-ray radiation. [17] The mechanisms of radiation damage are different for polymers and metals, since dislocations and grain boundaries do not have real significance in a polymer.
External beam radiation therapy (EBRT) is a form of radiotherapy that utilizes a high-energy collimated beam of ionizing radiation, from a source outside the body, to target and kill cancer cells. The radiotherapy beam is composed of particles, which are focussed in a particular direction of travel using collimators [ 1 ] .
Radiation retinopathy is damage to retina due to exposure to ionizing radiation. Radiation retinopathy has a delayed onset, typically after months or years of radiation, and is slowly progressive. In general, radiation retinopathy is seen around 18 months after treatment with external-beam radiation and with brachytherapy.
The penetration depth depends also on beam shape, narrower beam tend to have less penetration. In water, broad electron beams, as is the case in homogeneous surface contamination of skin, have d 80 about E/3 cm and R p about E/2 cm, where E is the beta particle energy in MeV. [24]
Electron-beam processing involves irradiation (treatment) of products using a high-energy electron-beam accelerator. Electron-beam accelerators utilize an on-off technology, with a common design being similar to that of a cathode ray television. Electron-beam processing is used in industry primarily for three product modifications:
Electron beam therapy is performed using a medical linear accelerator.The same device can also be used to produce high energy photon beams. When electrons are required, the X-ray target is retracted out of the beam and the electron beam is collimated with a piece of apparatus known as an applicator or an additional collimating insert, constructed from a low melting point alloy.
The high-current electron beam struck the patients with approximately 100 times the intended dose of radiation, and over a narrower area, delivering a potentially lethal dose of beta radiation. The feeling was described by patient Ray Cox as "an intense electric shock", causing him to scream and run out of the treatment room. [ 7 ]
Intraoperative electron radiation therapy is the application of electron radiation directly to the residual tumor or tumor bed during cancer surgery. [1] [2] Electron beams are useful for intraoperative radiation treatment because, depending on the electron energy, the dose falls off rapidly behind the target site, therefore sparing underlying healthy tissue.