Title: Clinical Relevance of Atomic Physics for Particle Therapy Speaker: Armin Lühr, IFA Time: Thursday, March 10, 15.15 to 16.00 Place: Fysisk Auditorium Abstract: Radiation therapy with photons has been proven to be an effective treatment against cancer. During the last century the paradigm of maximizing the radiation dose to the target while minimizing the dose to the surrounding healthy tissue has driven the development of new radiation delivery techniques such as the advanced intensity modulated radiation therapy and arc therapy. Particle therapy with fast ions has been known for a similar period since the beginning of last century. But only with the technical development of particle accelerators and the availability of 3D imaging techniques particle therapy has surged. Currently, it develops from a more experimental to a mainstream technique with around 35 particle therapy facilities in operation worldwide. The key advantage of particle therapy is that the accelerated ions deposit their energy mostly at the end of their track, the Bragg-peak, which can be adjusted to be inside the tumor volume by controlling the initial energy of the ions. That is, the stopping power of the particles mainly determines the depth-dose distribution. However, the mixed particle spectrum due to fragmentation, steep dose gradients, and different biological response behavior found in clinical ion beams pose several challenges for the accuracy of dose delivery and dose verification. In my talk I will outline the influence of stopping power on particle therapy. Additionally, I will address some of our recent activities related to stopping power including the open-source stopping-power library libdEdx and a study of stopping-power ratios relevant for accurate dosimetry in radiation therapy. Jacob Sherson and Aurélien Dantan Coffee, tea and cake will be served at 15.05 Dr. Jacob Friis Sherson Institut for Fysik og Astronomi Aarhus Universitet Ny Munkegade 120 8000 Århus C Tel.:8942 3680