X-rays, CAT scans and MRIs have become common terms in our everyday language, as these imaging techniques are increasingly being used to diagnose and treat diseases. But how much do you know about the professionals behind the scenes, the medical physicists who ensure that you receive safe doses of radiation? Prof Ng Kwan Hoong, from the Department of Biomedical Imaging, Faculty of Medicine, University of Malaya, shares more about his specialty.