Abstract:  Protons in the treatment of cancer have the distinct advantage over x-rays in that their depth of penetration into the body is limited by their energy (Bragg Peak). Beyond this limit, no dose is delivered and therefore critical structures (e.g. spine) receive no exposure at all. Currently, commercial proton units are of fixed energy and individual depth modulators must be used for different patients. A variable energy unit has now been developed in Russia and its characteristics will be described.
 

Resume:  Tim van Doorn received his BSc(Hons) from the University of Kent at Canterbury, UK, 1973, and his PhD from the University of Qld, 1988. He served as Medical Physicist, Royal Brisbane Hospital, 1976-1989, and then as a Senior Lecturer, QUT, 1990-1996.  He then moved to Adelaide where he is presently Director/Chief Physicist in the Department of Medical Physics, Cancer Centre, Royal Adelaide Hospital (RAH) and an Affiliate Associate Professor at the Department of Physics and Mathematical Physics, University of Adelaide.