1. Clinical Imaging Research Centre, National University of, Singapore 117599, Singapore
2. Joint Department of Physics, Royal Marsden NHS Foundation Trust, SM2 5PT, Sutton, UK
3. Institute of Cancer Research, London SM2 5NG, UK
4. Department of Nuclear Medicine and PET, Royal Marsden NHS Foundation Trust, SM2 5PT, Sutton, UK
5. Singapore Biomedical Imaging Consortium, Agency for Science Technology and Research (A*STAR) Biopolis Way, Singapore 138667, Singapore