Proton therapy is one of the most advanced forms of radiotherapy, utilizing very localized energy deposition that can be steered to precisely treat the tumor. These treatments are conventionally delivered from a limited number of directions. In discrete proton arc therapy, the protons are instead delivered over 20 to 30 directions. While treatment times for this technique could substantially decrease with updated treatment machines, discrete proton arc plans can be converted to standard plans and delivered by any existing proton machine.

The Medical Physics team at the Trento Proton Therapy Center recently finalized an extensive research study, where they compared their current treatment planning technique for head and neck cancer patients with proton arcs and noted large dose reductions outside the tumor volume with proton arcs, confirming what previous preclinical work had suggested. As a next step, they performed quality assurance measurements with a detector designed for arc therapy and assessed the impact on the clinical workflow in terms of, for example, treatment time. The conclusion was that discrete proton arc therapy delivered by their current treatment system from IBA is clinically feasible and treatments have now started.

Frank Lohr, Medical Chair, and Francesco Fracchiolla, Project Lead Arc Therapy, Medical Physicist,  both at Trento Proton Therapy Center: "In the same way as VMAT has revolutionized radiotherapy with photons, proton arc treatments have the potential to unlock significant additional benefits in proton therapy, taking it to the next level in several clinical indications The collaboration between radiation oncologists, medical physicists, and RaySearch has been the key to this progress in delivery technique."

Johan Löf, founder and CEO, RaySearch: "The start of proton arc treatments marks a major milestone in proton therapy, and it has been great to see the commitment of the team at the Trento Proton Therapy Center in introducing the technique into their clinical workflow. I am proud that RaySearch has played an instrumental role in pioneering proton arc therapy by advanced optimization algorithms and planning tools."