Christopher L Hallemeier1, Jonathan B Ashman2, Michael G Haddock3. 1. Department of Radiation Oncology, Mayo Clinic, Rochester, MN, USA. (Email: hallemeier.christopher@mayo.edu). 2. Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ, USA. (Email: ashman.jonathan@mayo.edu). 3. Department of Radiation Oncology, Mayo Clinic, Rochester, MN, USA. (Email: haddock.michael@mayo.edu).