1. Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
2. Department of Neurosurgery, University of California Los Angeles, Los Angeles, CA, USA.
3. Jonsson Comprehensive Cancer Center, University of California Los Angeles, Los Angeles, CA, USA.
4. Department of Radiation Oncology, University of California Los Angeles, Los Angeles, CA, USA.