Stereotactic Radiosurgery and Stereotactic Radiotherapy
Stereotactic radiosurgery (SRS) also use 3D technology. So does stereotactic radiotherapy (SRT). SRS applies a single large dose of radiation. It does this with a Gamma Knife — a modified linear accelerator. "It’s mostly used for brain tumors,” Coleman says. But the technique can also be used in other parts of the body. SRS is best used in organs that do not move, such as the brain. When it is, radiation can be delivered more accurately. That limits exposure to normal tissues. SRS works best on tumors that are three centimeters or smaller.
SRS of the brain uses a "fixed head frame." Graeme Fisher is a radiation oncologist and assistant professor at the University of Massachusetts Medical Center. He says there is typically a fixed head frame that’s attached to the patient’s skull. This provides accurate markers for the tumor target. The frame is bolted to the table or something stationary. That’s so the dose can be given within millimeters of the tumors edge. The fixed head frame is important. It keeps the patient still.
SRT delivers multiple large doses of radiation. They are, though, smaller than the dose given in SRS. SRT uses a non-fixed frame. The non-fixed frame is better for use on organs that move. For example, it might be used for the lung. Coleman says that because of new techniques, the treatment machine will be able to adjust for body movements like breathing.