Executive summary

Arc therapies such as VMAT are standard practice in photon radiation therapy due to, for instance, their dose shaping capabilities. Naturally, arc therapies do distribute dose to organs at risk (“integral dose”) more homogeneously. Irradiating a smaller volume of normal tissue is often mentioned as one of the key advantages of particle therapies. Thus, it sounds counterintuitive to suggest arc therapy with particles. Stewart Mein, PhD, MS, and co-workers created biologically optimized treatment plans on phantoms mimicking treatment sites in the head and neck, thorax and pelvic regions.