1Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland
2Department of Pharmaceutical Health Services Research, School of Pharmacy, University of Maryland, Baltimore, Maryland
3T.H. Chan School of Public Health, Harvard University, Boston, Massachusetts
4Procure Proton Therapy Center, Oklahoma City, Oklahoma
5Procure Proton Therapy Center, Somerset, New Jersey
6Willis-Knighton Proton Therapy Center, Shreveport, Louisiana
7University of Washington, Department of Radiation Oncology, Seattle, Washington.
8William Beaumont Hospital, Royal Oak, Michigan
9Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, Arizona