Catharine Clark is a Consultant Clinical Scientist at University College London Hospital and a Principal Research Scientist at the National Physical Laboratory in the UK. She is a Fellow of the Institute of Physics and Engineering in Medicine (IPEM) and chair of the ESTRO physics committee. She is an honorary Professor at UCL. Her research interests lie in dosimetric verification of advanced RT techniques and she has led several national dosimetry audits, including for rotational IMRT, lung and spine SABR and intra-cranial SRS. Each of these audits has involved collaboration with various groups from around the UK including the Radiotherapy Trials QA group, IPEM, the National Physical Laboratory and several hospitals. She has published widely in this area. Catharine is the past chair of the Global Quality Assurance of Radiation Therapy Clinical Trials Harmonisation group.