Cancer Answers 123

"Anyone who thinks that then final diagnosis is finally defined by a thin slice of tissue between two pieces of glass is only slightly less foolish than any pathologist who believes the same."

Stereotactic radiosurgery (SRS) differs from conventional radiotherapy in several ways. The efficacy of radiotherapy depends primarily on the greater sensitivity of tumor cells to radiation relative to normal brain tissue. With all forms of standard radiotherapy, the spatial accuracy with which the treatment is focused on the tumor is a secondary concern; normal tissues are protected by administering the radiation dose over multiple sessions (fractions) daily for a period of a few to several weeks. In contrast, radiosurgery, by its very definition, requires much greater targeting accuracy. With SRS, normal tissues are protected by both selectively targeting only the abnormal lesion, and using cross-firing techniques to minimize the exposure of the adjacent anatomy.