Image-guided Radiosurgery Using the Gamma Knife

Image guided brain surgery became a reality in the mid-1970s after the introduction of the fi rst methods to obtain axial imaging using computed tomography (CT) [9]. The recognition of cranial disease much earlier in its clinical course prompted the need for concomitant minimally invasive technologies to both diagnose and to treat the newly recognized brain tumors and vascular malformations. Subsequently, the development of magnetic resonance imaging (MRI) spurred further interest in accurate, safe, and effective guided brain surgery. Stereotactic radiosurgery (SRS) was the brain child of the pioneering brain surgeons, Lars Leksell and Erik-Olof Backlund at the Karolinska Institute [4, 5]. Stereotactic guiding devices were adapted to newly evolving imaging techniques, ranging from encephalography to angiography, CT, and MRI. These new techniques prompted further evaluation of stereotactic radiosurgery, a fi eld envisioned by Leksell in 1951. His concept that ionizing radiation could be cross fi red to destroy or inactivate deep brain targets without a surgical opening proved to be an enormous step forward in minimally invasive surgery. Under the watchful eye of Leksell, Gamma knife technologies gradually expanded in their role and their usage exploded across the fi eld of neurosurgery [1–3, 6–13]. Our efforts at the University of Pittsburgh began in 1987 with the introduction of the fi rst 201 source Cobalt-60 Gamma knife, which was the fi fth unit manufactured worldwide [7]. Since that time, more than 9000 patients have undergone Gamma knife radiosurgery at the University of Pittsburgh Medical Center. Our efforts fi rst began with usage of the original U unit. Since 1987 we have introduced each successive generation of the Gamma knife, starting with the B unit, the robotic assisted C unit, the 4C unit which advanced software capabilities, and the next generation and fully robotic Perfexion® Gamma knife (Fig. 1). Continuing incorporation of new imaging techniques, advanced long-term outcome studies, and multi-disciplinary care have facilitated the incorporation of Gamma knife radiosurgery into its application to more than 10% of patients undergoing neurosurgical cranial procedures at our center. Radiosurgery has refi ned the role of more invasive surgical tech-