The first proton therapy treatments in the Netherlands have taken place in 2018. Due to the physical properties of protons, proton therapy has tremendous potential to reduce the radiation dose to the healthy, tumour-surrounding tissues. In turn, this leads to less radiation-induced complications, and a decrease in the formation of secondary tumours. The Netherlands has spearheaded the development of the model-based approach (MBA) for the selection of patients for proton therapy when applied to prevent radiation-induced complications. In MBA, a pre-treatment in-silico planning study is done, comparing proton and photon treatment plans in each individual patient, to determine (1) whether there is a significant difference in dose in the relevant organs at risk (ΔDose), and (2) whether this dose difference translates into an expected clinical benefit in terms of NormalTissue Complication Probabilities (ΔNTCP). To translate ΔDose into ΔNTCP, NTCP-models are used, which are prediction models describing the relation between dose parameters and the likelihood of radiation-induced complications. The Dutch Society for Radiotherapy and Oncology (NVRO) setup the selection criteria for proton therapy in 2015, taking into account toxicity and NTCP. However, NTCP-models can be affected by changes in the irradiation technique. Therefore, it is paramount to continuously update and validate these NTCP-models in subsequent patient cohorts treated with new techniques. In ProTRAIT, a Findable, Accessible, Interoperable and Reusable (FAIR)data infrastructure for both clinical and 3D image and 3D dose information has been developed and deployed for proton therapy in the Netherlands. It allows for a prospective, standardized, multi-centric data from all Dutch proton and a representative group of photon therapy patients.