1 University of Cambridge, Department of Physics, Cavendish Laboratory, Cambridge, UK; University of Cambridge, Department of Oncology, Cambridge Biomedical Campus, Addenbrooke's Hospital, Cambridge, UK.
2 Department of Medical Physics and Clinical Engineering, Addenbrooke's Hospital, Cambridge, UK.
3 University of Cambridge, Department of Oncology, Cambridge Biomedical Campus, Addenbrooke's Hospital, Cambridge, UK.
4 University of Cambridge, Department of Physics, Cavendish Laboratory, Cambridge, UK.
5 Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge and National Institute for Health Research, Cambridge Biomedical Research Centre, Addenbrooke's Hospital, Cambridge, UK.