Radiation surgery is a cancer treatment designed to deliver radiation directly to the cancer within a patient while sparing the healthy tissue surrounding the cancer. It utilizes radiation to target the cancer rather than knives or scalpels to physically remove tissue during a surgery, but the precision and effectiveness of the treatment have earned it the name of "radiation surgery."

Although radiation surgery does not remove tumors or lesions for the body, it does lead to tumor and lesion shrinkage over time and can consequently be an attractive alternative for patients with inoperable tumors or aversions to open surgery. The treatment is also referred to as radiosurgery or external beam irradiation.

There are several different kinds of machines designed to perform radiation surgery. Each machine is suited to target specific cancer growths based on their size, location, and type of cancer cells. Three different kinds of radiation that they employ are proton, photon, and linac radiation.

Machines using a particle, or proton, beam are the newest and most expensive way to treat brain and body cancers. Consequently, there are only a few centers across the United States that offer this type of treatment and there is very little research accumulated on the effects it produces.

Linear accelerator machines are much more affordable than particle-based machine and are manufactured by several different companies. The Cyber Knife is just one of the many brands available, but they are all particularly useful when treating larger tumors with volumes of 3.5 cm or more and can be used to treat cancer throughout the body as well as the head and the neck.

The Gamma Knife is the most well-known and well-tested photon-based machine used in radiation surgery. In the past 40 years, over 350,000 people have already been treated with this machine. The Gamma Knife is one of the most precise radiation tools available because of way that it limits patient movement during treatment and the way that it delivers radiation to very specific areas. It is used primarily to treat cancer or tumors in the neck and brain though because those areas of the body are most easily immobilized.

IGRT, or Image-guided Radiation Therapy, uses imaging technology to locate a tumor immediately before radiation treatment which allows a physician to target the cancer with more precision than was traditionally possible. This method of treatment is not quite as precise as using a Gamma Knife, but IGRT can treat tumors in more locations throughout the body.

IMRT, or Intensity Modulated Radiation Therapy, hones in the cancerous tissue rather than healthy tissue by emitting several doses of radiation that varies in shape as well as intensity. The shape of the radiation waves are the key to sparing healthy tissue undesirable radiation exposure. This method is only used to treat stationary, small tumors.

A trained oncologist can help patients decide whether radiation surgery is the best treatment to pursue and which method will be the most effective.