Arjun Sahgal, MD (chief editor), is a leader in the field of high-precision stereotactic radiation to the brain and spine. After training at the University of Toronto, Ontario, Canada, in radiation oncology, he completed a fellowship at the University of California, San Francisco, in brain and spine radiosurgery with Dr. David Larson. Since then he has been recognized as a national and international clinical expert and research leader in radiosurgery. His main focus is on developing spine stereotactic body radiotherapy as an effective therapy for patients with spinal tumors. He has published numerous book chapters on the subject and more than 200 peer-reviewed papers in high-impact journals, including Journal of Clinical Oncology and The Lancet Oncology. He has edited or written several books specific to research on brain and bone metastases and is an editorial board member for several journals. He was chairman of the International Stereotactic Radiosurgery Society meeting (June 2013) and was a board member for the Brain Tumour Foundation of Canada and the International Stereotactic Radiosurgery Society. He has been invited to speak at several international meetings, has been a visiting professor at various universities, and leads several research groups. His further research activities involve integrating MRI into radiotherapy delivery, combining novel pharmacologic therapies with radiosurgery, and MRI-guided focused ultrasound. Simon S. Lo, MD, is professor of radiation oncology at Case Western Reserve University, Cleveland, Ohio, and director of radiosurgery services and neurologic radiation oncology at University Hospitals Seidman Cancer Center, Case Comprehensive Cancer Center, Cleveland, Ohio. Dr. Lo graduated from the Faculty of Medicine of The Chinese University of Hong Kong and did his residency in clinical oncology (Royal College of Radiologists, UK curriculum) at Queen Elizabeth Hospital, Hong Kong. He subsequently completed a residency in radiation oncology at the University of Minnesota, Minneapolis, and also received a grant from the American College of Radiation Oncology for a gastrointestinal radiation oncology fellowship at the Mayo Clinic (Minnesota). He was a visiting resident at Princess Margaret Hospital, University of Toronto, Ontario, Canada. He is currently chair of the American College of Radiology Appropriateness Criteria Expert Panel in Bone Metastasis and is the radiation oncology track co-chair for a Radiological Society of North America (RSNA) refresher course. He is an expert in brain and spinal tumors, stereotactic radiosurgery, and stereotactic body radiotherapy (SBRT). He has published more than 135 peer-reviewed papers, more than 50 book chapters, and three textbooks, including a comprehensive textbook in SBRT (27,000 downloads in 32 months). He has given lectures on SBRT to the American Society for Radiation Oncology (ASTRO), RSNA, the Radiosurgery Society, the International Stereotactic Radiosurgery Society, and the American Thoracic Society conferences and in multiple U.S. and international academic centers. He was also a member of both the ASTRO bone and brain metastases taskforces and contributed to the ASTRO guidelines for bone and brain metastases. He is on the editorial boards of multiple oncology journals and is a reviewer for The Lancet, The Lancet Oncology, Nature Reviews Clinical Oncology, Journal of Clinical Oncology, Radiotherapy & Oncology, and International Journal of Radiation Oncology: Biology and Physics. His areas of research are in brain tumors, stereotactic radiosurgery, radiobiological modeling for ablative radiotherapy, SBRT for lung, liver, and spinal tumors, and toxicities associated with SBRT. Lijun Ma, PhD, is professor in residence of radiation oncology physics and director of the Physics Residency Program at the University of California, San Francisco. Dr. Ma has served in American Association of Physicists in Medicine on multiple task groups and working groups. He currently co-chairs the normal tissue complication probability spine subcommittee and serves on the editorial board of Medical Physics. He is board certified by the American Board of Medical Physics and is a member of the American College of Radiology. He has been active professionally in the International Society of Stereotactic Radiosurgery and has served on its executive board. Dr. Ma has published more than 100 papers and more than 20 book chapters, and is a holder of three international patents. Jason P. Sheehan, MD, graduated with highest distinction in bachelors of chemical engineering at the University of Virginia, Charlottesville, Virginia, where he subsequently earned a master of science in biomedical engineering and a doctorate in biological physics. He earned his medical degree from the University of Virginia and completed his neurosurgical residency at the University of Virginia along with fellowships in stereotactic and functional neurosurgery at the University of