RCR Referral Guidelines

First published in 1989, The Royal College of Radiologists (RCR) has produced the referral guidelines, Making the best use of clinical radiology services, to help clinicians, radiologists, radiographers and other healthcare professionals to determine the most appropriate imaging investigation(s) for a wide range of clinical problems. They provide practical guidance based on the best available evidence, together with expert opinion where evidence is lacking or conflicting. 
Available on the Royal College of Radiologists website