The proton therapy facility at PSI is a world leading institute for clinical and research particle therapy. This project will build on this experience, particularly in the area of the treatment of mobile tumours in the thorax, and will deliver a number of tools that will be applicable to both proton and conventional radiotherapy (e.g. incorporation of functional imaging into the treatment planning process, motion models, libraries of 4D motions, etc.). This will help PSI retain its reputation as a leading researcher, developer and provider of state-of-the-art proton therapy. In addition, will provide a unique tool to the Swiss radiotherapy community for assessing, on a patient-by-patient basis, the best, and most personalized approach, to the treatment of lung cancers.