1. Department of Radiation Oncology, Louisiana State University School of Medicine, Shreveport, Louisiana 71130, USA
2. Department of Radiation Oncology, Louisiana State University School of Medicine; Willis-Knighton Health System, Shreveport, Louisiana 71103, USA
3. Summa Health System/Northeast Ohio Medical University, Akron, Ohio 44304, USA
4. Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA