External Bean Radiation Therapy
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Researchers in the field of radiation therapy continue to seek ways to improve the outcome of treatment. Their challenge is to get a high dose of radiation to the tumor while the surrounding normal tissue is protected from radiation damage. New methods for using radiation to treat cancer are being investigated. Many are promising but they are not yet widely available. You may hear the following terms that describe some of these new methods of radiation treatment:
IMRT or Intesnity Modulated Radiation Therapy uses special machinery that delivers tiny focused beams of radiation while it rotates around the patient’s head. The beams continuously change shape and size to conform to the shape and size of the tumor while avoiding vital structures in the brain. Computer software controls the intensity of the radiation.
Cyberknife is a new treatment that is being used to treat localized tumors. This system uses a miniature radiation machine and a robotic arm that moves around the patient while delivering small doses of radiation from hundreds of directions. During treatment a computer analyzes hundreds of images and adjusts for slight movements by the patient. This makes it possible to deliver the treatment without using a frame to hold the patient still. Only the tumor receives the high doses of radiation and healthy tissue is spared.
Three-dimensional conformal radiation therapy is a radiation technique that is being used in some cancer centers. Computer simulation produces an accurate image of the tumor and surrounding organs so that multiple radiation beams can be shaped exactly to the contour of the treatment area. Because the radiation beams are precisely focused, nearby normal tissue is spared. This technique is being used to treat prostate cancer, lung cancer, certain brain tumors and other other cancers.
Stereotactic radiosurgery or Gamma Knife uses gamma rays or a linear accelerator, is useful for treating certain kinds of brain tumors and some malformations in the brain’s blood vessels. One technique, called the ‘gamma knife,’ uses many powerful, precisely focused radiation beams. The patient wears a special helmet to focus the gamma rays and aim them at the target tissue from many directions. The treatment is painless and bloodless and, unlike conventional brain surgery, there is no danger of infection. Other systems use a linear accelerator to deliver the radiation in arcing paths around the patient’s head.
SBRT (Stereotactic Body Radiotherapy) is a method of radiosurgery recently developed for lung, GI and other tumors. It uses high doses of radiation delivered in fewer fractions than in conventional radiation therapy. An advanced treatment planning system permits precise targeting from many angles. As with other advances in radiation treatment, it allows high doses of radiation to be delivered to tumor tissue while reducing radiation damage to healthy tissue.