Funding
Research reported in this publication was partially supported by Varian Medical Systems, Palo Alto, USA. Role of funder/sponsor: This manuscript’s contents are solely the responsibility of the authors and do not necessarily represent the official views of Varian Medical systems. The funder had no role in the design, conduct of the trial; collection management, analysis, data interpretation; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.