Curative cancer treatment with radiation seeks to optimise the magnitude of the radiation dose to the treatment volume while restricting the dose to normal healthy tissue. With an increasing population of surviving cancer patients treated with radiation therapy, the harmful effects of the radiation to normal tissue are becoming more evident. The ALLEGRO project will address the many aspects of normal healthy tissue damage that are not yet well understood in both conventional treatment techniques and emerging techniques (protons, heavy ions). The project will include measurement of radiation doses outside the treatment volume and investigation of the accuracy of methods of dose calculation in this region. The extensive existing databases of radiation treatments and outcomes will be used to investigate models of normal tissue damage and second primary cancer. The measurements and data analysis will be supported by theoretical modelling and surveys to develop the link between radiobiological mechanisms and empirical normal tissue complication (NTCP) models, and to extend conventional models to apply to the emerging techniques. The project is restricted to two years, so there will be a limit to the amount of new research possible. Therefore an essential part of the project will be to engage a forum of experts to redefine the current knowledge on normal tissue damage following radiotherapy, identify gaps in the knowledge and make recommendations for future research, data collection, and technological developments. The final report will consist of a series of focused documents directed to clinicians (for the application of normal tissue risks in treatment optimisation), equipment manufacturers (recommendations on safety design), and the research community (summary of knowledge and recommendations on data collection and project proposals).