Malcolm received his MSc in Medical Radiation Physics from University College London in 1993 and his PhD in Radiation Physics from the University of Surrey in 2002. After working at the National Physical Laboratory for more than a decade, he joined the Ionizing Radiation Standards group at the National Research Council Canada, where he served as Team Leader, Medical and Industrial Dosimetry within the Metrology Research Centre from 2014 to 2024. He is currently a Principal Research Officer, focussing on the maintenance and development of primary dosimetry standards for a wide range of beam modalities, from synchrotron x-rays to high-energy protons. He is also involved in leading the development of best practice guidelines and dosimetry protocols, including for megavoltage photon and electron beams, HDR brachytherapy and UHDR dosimetry. Although his research is mainly applied to radiation therapy, he is also active in investigating dosimeters for radiation processing and supports NRC activities in radiation protection dosimetry.
Dr McEwen is Adjunct Professor in the Department of Physics at Carleton University, Executive Director of the Ottawa Medical Physics Institute, Chair of the International Committee on Ionising Radiation (Section I) of the CIPM, and Vice-president of the Canadian Organization of Medical Physicists. He was elected to the Commission in 2025.