How is Stereotactic Radiosurgery different from conventional radiotherapy?
Conventional radiotherapy is a very useful treatment modality for many brain tumors. This modality is characterized by: • Large volumes of irradiation (sometimes including a large volume of normal brain) and • Fractionation. Fractionation means that the treatment is divided into multiple smaller doses (fractions) of radiation. The reason for fractionation is to improve the radiation effect on the tumor while minimizing the effect on the normal brain. Normal brain tolerates small, daily doses of radiation relatively well. The tumor does not tolerate the small daily doses, resulting in control of the tumor. By exploiting this difference in response, the fractionated treatment can be very effective in reducing or even eliminating the tumor while sparing the normal brain. This concept of fractionation is also very important for radiosurgery, as is discussed below. How is precise localization achieved? For Stereotactic Radiosurgery the stereotactic frame provides an “external frame of refer
