This book is intended to help physicians understand the nuances of ordering the most appropriate radiological exams for their patients, based primarily on the academic practice at the University of Washington and the evidence-based knowledge embedded in the American College of Radiology Appropriateness Criteria(R). Radiologists have a unique perspective on the appropriateness of radio-logical exams because they see the results of imaging exams in much larger numbers than any individual referring clinician. It is from this perspective that we have written this book.