The Physicist and the Flea Market: At the Birth of Modern Image-Guided Radiotherapy

I have always loved the ‘Waterloopplein’ flea market in my birth town of Amsterdam. Electronics was my oldest hobby, taking radios and alarm clocks apart as young as seven years, and demonstrating how a transistor works to the classroom at 11. I became interested in computers when as a 12 year old boy I read a 1967 Life magazine educational handout article explaining the IBM 360 computer in simple terms with beautiful pictures. Combining my physics education with my self-taught expertise in building computers from old parts, I set out a long career in developing technical tools and methods to improve the accuracy of radiotherapy, focusing on imaging and image processing. I first developed an x-ray camera for verifying the radiation treatment. Its prototype contained many parts acquired at the flea market. Once this camera was successfully developed, I started developing software to analyse the images. After some failed attempts I developed the first automated system for analysing such images in 1990 that has been in clinical use for decades. Later work extended the image analysis to three-dimensional images developing one of the first methods to combine CT and MRI scans of patients. The software was next used to analyse radiotherapy uncertainties such as organ motion and tumor delineation variation between physicians. I pioneered many methods that came together in the imaging software developed for a cone-beam CT guided radiotherapy machine that has been on the market since 2005 and has been used to treat millions of patients. I moved to Manchester in 2015, and now focus on using treatment and image data of thousands of patients to improve treatment of future patients. Having an interest in flea markets has taught me to recycle, and study and repair many devices. I sincerely believe this experience has helped me enormously to successfully develop medical imaging systems that are in wide use today.