The clinical outcome after external beam irradiation for prostate cancer is disappointing in the advanced tumor stages. There are indications that an increase in radiation dose to the tumor will improve outcome significantly, especially to the biologically active tumour parts within the cancer area. Until recently no imaging equipment was available to define both the anatomic and biologically active tumor parts. Now, at the Center for Biological Imaging and Adaptive Radiotherapy, equipment is at hand that will be able to visualise the areas mentioned above. When combining the data of these imaging modalities it might be possible to create an optimised irradiation plan. This study is a planning study in which, on 15 patients, the different anatomical and biological imaging data per patient will be evaluated, matched and finally a theoretical improved irradiation treatment plan will be made. This research complies with the current opinion on radiation development. Progress in functional imaging is likely to provide the tools required for individualised risk-adapted radiotherapy.