The present chapter is focused on the role of positron emission tomography/computed tomography (PET/CT) and [11C]-labelled Choline ([11C]Choline) for the management of prostate cancer patients for radiation therapy planning. Although still a matter of debate, PET/CT with [11C]Choline is not routinely recommended for selecting patients for prostate cancer primary radiation treatment. However, due to its high accuracy in detecting and localizing recurrences when a biochemical failure occurs, [11C]Choline PET/CT may play a role in the re-staging phase to distinguish patients with local versus distant relapse, thus influencing patient management (curative versus palliative therapy). Limited data are currently available on the role of [11C]Choline PET/CT in target volume selection and delineation. According to available literature, [11C]Choline PET/CT is not clinically recommendable to plan target volume both for primary prostate treatment and for local recurrence. Nevertheless, promising data suggested a potential role of [11C]Choline PET/CT as an image guide tool for the irradiation of prostate cancer relapse.