Making the best value of clinical radiology: iRefer Guidelines, 8th edition.

New uses of medical imaging as well as over-diagnosis and wasteful imaging have led to a 10% per annum growth in computed tomography (CT) and magnetic resonance imaging (MRI). Personalised value to the patient will be helped by referral guidelines for the best test first, adding evidence-based technical value to the investigation to answer the clinical question, thus providing allocative value to the commissioners of medical imaging. Appropriate imaging is driven by the need for effective decisions, radiation safety, and cost awareness. The eighth edition of The Royal College of Radiologists' iRefer guidelines addresses 270 common clinical settings providing imaging referral advice, particularly for primary care practitioners. There is a new section addressing asymptomatic individuals for screening and health assessment. Multiple formats, including print and web formats, will be augmented by a clinical decision support tool to bring guidance closer to referrers. Established evidence identified a reduction in requested examination numbers by typically 20%, with more recent studies showing appropriate imaging in 80-90% of cases, correctly allowing some flexibility for individual circumstances. The perceived value of referral guidance may be judged by the mandated use in the USA, the requirement for availability in Europe, and the wish by many elsewhere to avail their patients of best imaging practice.