Radiological sciences, past and present.

Few observations can have been as rapidly and widely disseminated in medicine as the diagnostic X-ray (radiograph). The first few decades after Röntgen's discovery saw technical developments that made radiography more practical, quicker, safer for both imager and patient, and able to achieve greater contrast. This article reviews the history of imaging but it also looks to the future and begins to open up some of the issues that radiology faces in the 21st century--issues that the next six articles in this Lancet series will enlarge upon. The conventional radiograph remains the most common medical image but a host of new techniques have come along. Are they research tools, clinical methods, or both--and how, in an age of sensitivity about the costs of health care, do they stand up?