Radiology is a science involving the medical use of x-rays in the diagnosis of disease, fractured bones, detect injury or infection, and/or to locate foreign objects in soft tissue. A radiologist is a physician specializing in this science and a radiographer (or radiologic technologist) produces radiographic images under the direction of the radiologist. Radiographers make up the largest group of imaging professionals. Their principal duties consist of performing diagnostic x-ray procedures of patients, with the lowest amount of radiation exposure possible. They also assist in fluoroscopic examinations and in special radiographic procedures. Other tasks performed by radiographers vary. Radiographers must be able to handle seriously ill and injured patients to obtain the maximum amount of information without injury to the patient and with the least amount of pain and discomfort from the examination. They may assist the radiologist in some complex procedures, often involving the injection of opaque media through needles or catheters. Radiographers must be well educated and experienced in aseptic techniques, requiring skills comparable to those of nurses in some specialties. Most technologists are employed in hospitals, clinics, and physicians' offices.