Stereotactic radiosurgery and radiotherapy refer to the precise delivery of radiation to targeted areas, such as brain tumors or AVMs, abnormal tangles of blood vessels. They differ from normal radiation regimes in that very little if any normal tissue is exposed to the radiation. The difference between stereotactic radiosurgery and stereotactic radiotherapy has to do with the intensity and duration of the radiation treatments.
Stereotactic radiosurgery delivers radiation at a very high intensity, all at once, to a small area. It is a way of treating brain disorders with a precise delivery of a single high dose of radiation in a one-day session.
Stereotactic radiotherapy delivers radiation at different times, at lower intensities and to larger areas. One benefit of this technology is its ability to easily treat very large tumor volumes by treating over time during cell division.
There are three different technologies that are used for stereotactic radiosurgery or stereotactic radiotherapy:
- Cobalt60 based (photon) – gamma knife surgery
- Linear accelerator-based (photon) has the ability to perform radiosurgery on larger tumors by delivering treatments over several days, which is referred to as radiotherapy. This flexibility is not available with other machines. The linear accelerator uses one large, intense radiation beam that is redirected in many arcs to lessen the effect on healthy tissue. These machines can be utilized throughout the body as well as the head and neck.
- The particle beam or cyclotron treats brain tumors and body cancers in a fractionated manner.
Radiosurgery is limited to the head and neck since these areas can be immobilized to completely restrict the head's movement, permitting the most precise and accurate treatment. Radiosurgery administers a higher intensity dose of radiation and is not used to treat areas of the body other than the head because there is no way to immobilize the body to treat a tumor in one session.
Stereotactic radiotherapy, which administers lower-intensity doses of radiation during a period of days or weeks, may be administered in the body with the assistance of removable masks and frames that achieve some degree of lesser mobilization.
In general, radiation does not remove the tumor or lesion, but it damages the DNA of the tumor cells. This damaged DNA eventually causes the cells to die because they cannot reproduce or maintain their function. Radiation causes the blood vessels of lesions, such as AVM's, to thicken and close. The shrinking of a tumor or closing of a vessel.