RecruitingRadiation therapyIMPT Dose Escalation for NSCLC (HyDose)The goal of this clinical pilot trial is to learn if dose to the tumor in the lung can be safely increased using proton therapy in stage III non-small-cell lung cancer patients receiving combined chemotherapy and radiotherapy. The main questions it aims to answer are: * Is the risk of severe radiotherapy toxicities (requiring hospital admission) within acceptable margins ? * What is a rough estimate of the effect of the treatment under study? Compared to standard care in our clinic, all participants in this pilot trial will * Receive a higher dose of proton therapy to the tumor in the lung albeit with the same number of radiotherapy visits as the current standard treatment. * Receive two additional follow-up visits at the clinic after treatment, namely 4 and 6 weeks after finishing radiotherapy. * Two additional blood withdrawals at the last week of radiotherapy and 4 weeks after finishing radiotherapy, to measure a type of white blood cells. * Receive an extra quality of life questionnaire at the last week of radiotherapy.