Gastrointestinal Fluoroscopy: Radiation Doses

摘要

This chapter reviews the assessment of radiation doses to patients undergoing clinicalgastrointestinal (GI) fluoroscopic examinations. GI fluoroscopy is a very common clinical procedure; in 2004, about 7.2 million examinations were performed throughout the United States (C. Meghea, American College of Radiology, oral communication, April 2006). The radiation doses for these procedures are among the highest in radiology; only cardiac catheterization and interventional angiography have the potential to deliver higher radiation doses to the patient (1,2). Typical GI fluoroscopic examinations may even deliver higher radiation doses than a typical computed tomographic (CT) body examination (3). Moreover, patients at risk of GI tract cancer may undergo several barium enema and/or upper GI examinations during their lifetimes. Thus, it is important to understand (a) the methods employed to determine patient radiation doses, (b) the various factors that contribute to patient radiation exposure, and (c) the different ways in which the radiation doses can be expressed. Other chapters in this syllabus will address image quality assessment and clinical practice; this chapter will restrict itself to radiation dose issues. Unfortunately, radiation doses for GI procedures have a wide range of values (4-6). The patient's size, sex, and physical composition can result in substantial variations in the radiation doses. The fluoroscopic equipment and its features also have a dramatic effect on patient radiation doses (3,7,8). Moreover, most physicians only superficially understand their role in controlling patient radiation dose during GI fluoroscopy (9). The protocols for fluoroscopic studies directly affect the magnitude of patient radiation doses. These protocols specify (a) the duration of fluoroscopic imaging, (b) the number of radiographs ("spot" images) obtained, and (c) the selection of equipment options, such as the fluoroscopic pulse rate and the field of view (FOV) for the image receptor.