As the region that is treated with classical radiotherapy is much larger, a great amount of healthy cells, tissues and organs located in the vicinity of the treated target is damaged. The result is the toxicity from less to severe amounts.
In Stereotactic Radiosurgery, the therapy is focused with great precision on the target hence the vulnerability of surrounding healthy cells and tissues is minimal and almost nonexistent. Therefore the toxicity does not occur.
During the treatment with CyberKnife , and in the case that a large target region needs to be radiated (a few centimeters), the precision of radiation is such that there is minimal dispersion of radiation on surrounding tissues and therefore the toxicity is minimal.