Intracranial Stereotactic Radiosurgery Concepts and Techniques Antonio A.F. De Salles, MD, PhD a,b, *, Alessandra A. Gorgulho, MD, MSc a,b , Julio L.B. Pereira, MD a,b , Nancy McLaughlin, MD a,b INTRODUCTION Stereotactic radiosurgery evolved based on two good ideas. First, treating a lesion in human tis- sues with external beam radiation, described by Kohl 18 years after the discovery of X-rays. 1 The second hinged on the work of Horsley and Clarke, neurosurgeon and mathematician, respectively, who developed a tool to localize intracranial struc- tures in three dimensions. This work resulted in a stereotactic atlas of the primate brain published in 1908. An atlas that combined the use of this development was the subject of Spiegel’s re- ported human stereotactic atlas in 1952. 2,3 The concept of applying focal X-rays as a thera- peutic tool evolved using spiral converging beams, pendulum-directed beams, and finally rigid hemi- spheric distributed beams directed with stereotac- tic precision. 4 It was Lars Leksell, a practicing functional neurosurgeon at Karolinska University in Stockholm, Sweden, who integrated stereotac- tic precision with the penetrating capability and the tissue effect of the photon beam. As widely described, Leksell attached an X-ray tube to his stereotactic arc centered frame and delivered ra- diosurgery to the first patient submitted to the technique, targeting the trigeminal ganglion for treatment of trigeminal neuralgia. The term “radio- surgery” was coined. 2 Radiosurgery evolved during the last half of the twentieth century linked to the explosion of imag- ing techniques. 5 Because it was dependent on ventriculography, cysternography, and angiog- raphy, the applications of radiosurgery were largely limited to pathologies visualized by these tech- niques. Functional applications were based on principles of functional neurosurgery localization, for example using the anterior commissure and Disclosures: The authors have nothing to disclose. a Department of Neurosurgery, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA; b Department of Radiation Oncology, David Geffen School of Medicine, Univer- sity of California Los Angeles, Los Angeles, CA 90095, USA * Corresponding author. Department of Neurosurgery, David Geffen School of Medicine, University of California Los Angeles, 10495 Le Conte Avenue, Suite 2120, Los Angeles, CA 90095. E-mail addresses: afdesalles@yahoo.com; adesalles@mednet.ucla.edu KEYWORDS  Stereotactic radiosurgery  Gamma Knife  Linear accelerator  Novalis  Cyberknife  Tomotherapy KEY POINTS Readers of this article will learn:  The history of device development for radiosurgery.  The technical nuances of each intracranial radiosurgery device.  Step-by-step performance of a radiosurgery procedure.  The need of a team approach in radiosurgery.  The expansion of intracranial radiosurgery to other areas of the body. Neurosurg Clin N Am 24 (2013) 491–498 http://dx.doi.org/10.1016/j.nec.2013.07.001 1042-3680/13/$ – see front matter Ó 2013 Elsevier Inc. All rights reserved. neurosurgery.theclinics.com