After a long period of societal discussion, proton therapy became available in the Netherlands in 2018. This therapy was introduced to the Netherlands in a unique manner. The proton centres have been given permission to treat a maximum of 2,200 patients per year, 4.4% of the total number of patients who receive radiotherapy. This group is selected using carefully chosen prediction models to estimate the chance of side effects. An individual patient will only be eligible for proton therapy when a clinically relevant difference in side effects can be expected in comparison with current photon therapy. What prediction models should be used and what differences in side effects justify the use of proton therapy are, and will be, laid down in national indication protocols. We expect that this will enable us to extend the good international reputation that the Netherlands has in the area of radiotherapy, and to cooperate in bringing proton therapy to a higher level internationally.