Cyberknife Stereotactic Surgery, developed in 1997 by John R. Adler, professor of neurosurgery and radiation oncology at Stanford University, and manufactured by Accuracy, Inc., provides a frameless surgery robotic system that focuses high concentrations of radiation to target small, critically located tumors without invasive skull surgery. This image-guided robotic radiosurgery has helped replace external beam radiotherapy and has been shown to be safe and effective for patients with pituitary adenomas (Cho et al., 2009). This procedure uses a robot that manipulates an . The robotic arm carries a compact 130 kg 6 MV X-ray linear accelerator called LINAC and maneuvers to direct the LINAC to the target location (Cho et al., 2009, Adler, Murphy, Chang, & Hancock, 1999). Two diagnostic . Real-time x-rays are acquired at repeated intervals during treatment with the aid of two silicon x-ray screens capable of generating high-resolution digital images. They are automatically recorded to digitally reconstruct radiographs originating from the treatment planning computed tomography (CT) scan. This process allows the position of the skull and treatment site, obtained from the CT scan, to be translated into the LINAC coordinate frame. Communication between the imaging system and the robotic arm of the Cyberknife regulates paper half, SRS in tumor volume, visual disturbances and hypopituitarism. Additionally, he has successfully treated large tumors that are not normally treated with Gamma Knife SRS, or tumors close to the optic pathways, with the use of multisession hypofractionated stereotactic radiation therapy. In another study by Cho et al. (2009), the tumor control rate was 92.3%, comparable to other forms of fractionated radiation therapy and was similar to that of Gamma Knife. Endocrinopathies have shown 100% improvement rates, similar to Gamma Knife and superior to other fractionated radiation. Vision loss, a common complication of radiation therapy, produced complication rates of 7.6%, similar to those of Gamma Knife and higher than other fractionated radiation. Additionally, no cases of pituitary dysfunction were found in the study, which may have been the result of multisession radiosurgery.