Declaration of interest
A Sahgal has conducted past educational seminars with Medtronic, Elekta AB, Accuray Inc., and Varian medical systems, has a research grant with Elekta AB, received travel accommodations/expenses by Medtronic, Elekta and Varian, and is a member of the Elekta MR Linac Research Consortium. ST Chao has received honorarium from Abbie, Zeiss, and Varian Medical Systems. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.