Roadmap: proton therapy physics and biology

Harald Paganetti*, Chris J Beltran, Stefan Both, Lei Dong, Jacob B Flanz, Keith M Furutani, Clemens Grassberger, David R Grosshans, Antje-Christin Knopf, Johannes A Langendijk, Håkan Nyström, Katia Parodi, Bas W Raaymakers, Christian Richter, Gabriel O Sawakuchi, Jacobus Maarten Schippers, Simona F Shaitelman, Kevin Teo, Jan Unkelbach, Patrick WohlfahrtAntony John Lomax

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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The treatment of cancer with proton radiation therapy was first suggested in 1946 followed by the first treatments in the 1950s. As of 2020, almost 200 000 patients have been treated with proton beams worldwide and the number of operating proton therapy (PT) facilities will soon reach one hundred. PT has long moved from research institutions into hospital-based facilities that are increasingly being utilized with workflows similar to conventional radiation therapy. While PT has become mainstream and has established itself as a treatment option for many cancers, it is still an area of active research for various reasons: the advanced dose shaping capabilities of PT cause susceptibility to uncertainties, the high degrees of freedom in dose delivery offer room for further improvements, the limited experience and understanding of optimizing pencil beam scanning, and the biological effect difference compared to photon radiation. In addition to these challenges and opportunities currently being investigated, there is an economic aspect because PT treatments are, on average, still more expensive compared to conventional photon based treatment options. This roadmap highlights the current state and future direction in PT categorized into four different themes, 'improving efficiency', 'improving planning and delivery', 'improving imaging', and 'improving patient selection'.

Original languageEnglish
Article numberARTN 05RM01
Number of pages62
JournalPhysics in Medicine and Biology
Issue number5
Early online date23-Nov-2020
Publication statusPublished - 26-Feb-2021


  • proton radiation therapy
  • dosimetry
  • imaging

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