What will the medical physics of proton therapy look like 10 yr from now? A personal view

Despite growing rapidly, proton therapy is still a relatively immature treatment modality, at least in comparison to conventional radiotherapy using photons. As such, in this article, the author gives a very personal view of some of the potential areas for development in medical physics for proton therapy in the next 10 yr by identifying six topics for detailed discussion. The first of these are all related to reducing various "parameters" of proton therapy treatments (size and cost, treatment times, penumbras, and margins), while the second group are related to providing more quantitative "knowledge" about the quality of the treatments we are delivering. In conclusion, there is much interesting and important work still to be done in many areas of medical physics related to proton therapy, of which, the topics selected here are just the tip of the iceberg.