Imaged-guided radiotherapy (IGRT) is not a new technique; rather, it has evolved over the past few decades. It has been defined in many ways, but for the purposes of this Editorial it can be thought of as any imaging at pretreatment and delivery, the result of which is acted upon, that improves or verifies the accuracy of radiotherapy. Although imaging at the time of treatment delivery, for example electronic portal imaging, has been available since the early 1990s, the consistency and frequency of use throughout the UK has been variable. This led to the publication of On target: ensuring geometric accuracy in radiotherapy in 2008 [1] detailing guidance for twodimensional imaging, which included explanations of methods to determine set-up error and to calculate treatment set-up margins. In parallel with the publication of On target: ensuring geometric accuracy in radiotherapy [1], the National Radiotherapy Advisory Group report [2] set the national strategy for radiotherapy and advised that the National Health Service should aspire to image-guided fourdimensional adaptive radiotherapy as the future standard of care for radical radiotherapy treatment [2]. Since then, significant technical advances have occurred in all aspects of radiotherapy from target delineation, radiotherapy planning and treatment delivery and, in particular, verification. Therefore, the effective implementation and evaluation of new IGRT techniques is essential. Although IGRT is an essential component of fourdimensional adaptive radiotherapy, it should also be a core component of all radiotherapy treatments, both radical and palliative. As with the widespread implementation of intensity-modulated radiotherapy (IMRT), there is a lack of high-level evidence to show benefit in local