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6 Types of External Cancer Radiation Therapies
   

Going through external beam radiation therapy is a lot like getting a routine x-ray: You feel nothing, and you see nothing. You do, however, hear something - the buzzing and clicking of the machine that delivers the radiation to the cancer site.

Most often, the machine used during external radiation therapy is a linear accelerator (LINAC for short). A time-tested machine that is updated as improvements are developed, the LINAC can deliver beams of both low and high-energy photons and electrons. Other machines used in external beam radiation therapy include orthovoltage x-ray machines and cobalt-60 machines, which deliver low-energy beams.

Several different types of external beam radiation are available. Keep in mind that the necessary equipment is not always available in smaller hospitals. To get the treatment you need, you may have to travel to a medical center that has the up-to-date, high-tech equipment required.

1. Photon/electron Radiation Therapy: The most common form of radiation therapy in use is high-energy photon (x-ray) beam radiation, which is used to destroy or shrink tumors and to destroy any cancer cells in an area where a tumor has been removed. Most cancers are treated with high-energy photon radiation. Low-energy radiation is used to treat surface tumors.

Electrons are charged particles used to treat more superficial tumor sites, such as lymph nodes in the neck; to boost treatment of a breast cancer site; or to treat skin cancers. Electron beams have different energies and must be carefully chosen for the appropriate depth of the cancer being treated. Often, patients are treated with a combination of photons (x-rays) and electrons (accelerated charged particles).

2. Three-Dimensional Con Format Radiation Therapy (3D-CRT): Three-dimensional conformal radiation therapy calls on computers and computer-assisted tomography scans (also know as CT or CAT scans), along with magnetic resonance imaging scans (MR or MRI scans), to create a three-dimensional representation of a tumor and the surrounding organs. Tools called multileaf collimators, or blocks, match the radiation beams to the size and shape of the tumor. This allows for less radiation exposure to nearby normal tissue.

3. Intensity modulated Radiation Therapy (1MRT): This type of radiation therapy is a form of 3D-CRT that breaks the radiation beam into many small "beamlets," with individually adjusted levels of intensity. Sometimes, IMRT can be used to deliver a higher dose of radiation directly to the tumor while limiting radiation received by normal tissues. This currently is the most precise, cutting-edge form of external radiation, and it requires meticulous planning and quality assurance on the part of the radiation oncologist, physicist, dosimetrist, and radiation therapists.

4. Proton Beam Radiation Therapy: Proton beam therapy uses protons (charged particles), rather than x-rays, to treat cancer. Proton therapy provides a sharper beam, which may be useful in treating lesions close to the spinal cord, for example. However, there's a price to pay for that precision: potentially intensified side effects. This therapy is very costly, and few proton beam therapy machines are available in the United States.

5. Neutron Beam Radiation Therapy: Some tumors that are radio-resistant, or difficult to kill with conventional radiation therapy, can be treated with neutron beam therapy. This type of therapy occasionally is used to treat some inoperable tumors, though most often such tumors are treated with radiation therapy using photon (x-ray) and electron radiation therapy.

6. Stereotactic Radiation Therapy: In Stereotactic radiation therapy, high doses of radiation are focused on a small area, no larger than 2 to 3 centimeters. Also, many beams of high-dose radiation converge on the tumor from different directions. This therapy is often used to treat small tumors in the head, brain, lungs, and other sites.

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by SolveYourProblem.com : 2006

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