A challenge for high-precision radiation therapy: the case for photons.

The sophistication of Hadron facilities led to major technical and conceptual advances in the treatment immobilization, reproducibility, planning and execution. Some of these developments have had a pivotal impact on conventional treatments, which can now approach the dose localization advantage of protons in the majority of clinical situations. While the biological advantages of neutrons may finally be combined with excellent dose localization in Heavy Ion Facilities, modern surgical or systemic treatment methods may reduce high LET advantages. Clinical trials still need to define the relative merits of these approaches in their most modern implementation. The advantage gap has certainly been narrowed by recent developments in conventional therapy.