A fluoroscope is an x-ray device that allows live images to be projected onto a viewing monitor during diagnostic and interventional procedures.
Purpose
A fluoroscope is used for real-time imaging of various anatomical areas during a diagnostic or interventional procedure. Fluoroscopy produces a live image of the area of interest, and can be used to view such motion as blood flow and catheter insertion. In contrast, radiography, or x-ray imaging, produces a still image on film.
The term fluoroscope generally refers to a mobile radiographic/fluoroscopic unit, also called a mobile C-arm because of its shape. A mobile C-arm system consists of two wheeled units: one carries the imaging arm, x-ray generator, and control console, and the other carries the image display monitors and image processing and recording devices. The imaging arm, which is shaped like the letter C, has an x-ray tube mounted on one end and an image intensifier mounted on the other end. The x-ray generator supplies the power to the x-ray tube, which emits x rays that pass through the patient and are absorbed by the image intensifier. The image intensifier is a phosphor screen that converts the x rays into light, which is then scanned and transmitted by a charge-coupled device (CCD) camera to a display monitor.
Fluoroscopy is also performed using larger stationary radiographic/fluoroscopic systems that include a patient table, an x-ray generator, an x-ray tube, an image intensifier, and an image display system configured in a shielded room. The term fluoroscope may be used to refer to the components of this stationary system that perform fluoroscopy, but it is most commonly used in reference to a mobile system.
Fluoroscopy is performed in surgical, orthopedic, critical care, emergency care, and diagnostic radiology settings. In addition, mobile fluoroscopes are used to image patients on stretchers, beds, or examination/procedure tables when they cannot be transported to the radiology department.
Scaled-down compact fluoroscopes that can be handheld are also available and are designed for fast, continuous imaging of the extremities at various angles. Mini C-arms may be used in the emergency department, during surgery, in a physician's office, in sports medicine and physical therapy, and in the field such as an accident site.
In 2000, a fluoroscope with a navigational or surgical guidance computer was introduced to improve instrumentplacement and imaging during minimally invasive surgical procedures, particularly those involving the spine.
Operation
The fluoroscope is maneuvered in such a way that the patient, and the anatomical area of interest, is positioned between the x-ray tube and the image intensifier. The operator uses the control console to set imaging parameters. The intensity of the x rays is controlled with the milliamperage (mA) setting, and the energy and intensity of the x rays are controlled with the peak kilovoltage (kVp) setting. A typical fluoroscopy image setting is 70 kVp at 2 mA. Most mobile C-arms have capabilities for magnified views, automatic brightness stabilization to maintain a constant brightness during the exam, and last-image hold to freeze the last acquired image on the monitor.
During fluoroscopic imaging, the patient is exposed to radiation; continuous fluoroscopy for long periods (e.g., during a surgical procedure) can deliver a significant radiation dose. Therefore, most systems have a pulsed fluoroscopy mode, which allows the x-ray output to be pulsed for periods ranging from 10 milliseconds to 30 times per second, and displays the image acquired with each pulse. Although the image on the monitor may be jumpy, radiation exposure to the patient can be reduced by as much as 75% with this mode. Dose reduction is especially important in pediatric patients and young adult patients of reproductive age. Clinical staff are also exposed to radiation, and portable radiation shields, lead aprons, and radiation badges should be worn by all staff present during fluoroscopy.
All images displayed on the monitor can be saved to a disk, video disk, compact disk, or tape. Some systems have digital capabilities that allow storage in digital memory or on a computer network. A videocassette recorder or digital recorder can be used to record several minutes of real-time fluoroscopy. Snapshot images can also be printed as hard copy using video printers, thermal printers, or a multi-format camera (a camera that records and prints multiple images; for example, four images on one film).
Maintenance
A fluoroscope is usually maintained either through a service contract with the manufacturer, a third-party service company, or by the hospital biomedical engineering department. The x-ray technologist operating the fluoro-scope may perform periodic performance testing to check image quality, radiation dose, and other imaging parameters. A quality control program should be implemented
KEY TERMS
Brachytherapy—A radiation therapy treatment in which a radioactive source material is inserted, injected, or implanted into the cancerous area; fluoroscopy is frequently used to guide placement of brachytherapy sources.
Discography—A radiographic/fluoroscopic imaging procedure that involves injecting contrast material into an intervertebral disk.
Endoscopic retrograde cholangiopancreatography (ERCP)—A procedure that involves inserting an endoscope through the mouth, esophagus, stomach, and into the first part of the small intestine (the duodenum) to examine the pancreas, pancreatic ducts, and bile ducts. A catheter is threaded through the endoscope to inject dye, and x-ray and fluoroscopic imaging are performed.
Lithotripsy—A procedure that uses fluoroscopic guidance to locate and break up stones in the urinary tract and gallbladder.
Myelography—A fluoroscopic imaging procedure that examines the spinal cord and is used for diagnosing such conditions as spinal abscesses, tumors, and dislocated intervertebral disks.
to ensure optimal image quality and minimal radiation doses.
Health care team roles
Fluoroscopic imaging may be performed by x-ray technologists, radiologists, surgeons, cardiologists, and other health care professionals. For such diagnostic procedures as an upper gastrointestinal (GI) series, the fluoroscopic examination is performed by a radiologist and an x-ray technologist in a hospital radiology department or an outpatient imaging center. For such orthopedic procedures as arthroscopy, an orthopedic surgeon and x-ray technologist perform the fluoroscopic examination. For interventional diagnostic and therapeutic procedures, an interventional radiologist, cardiovascular specialist, and x-ray technologist are involved in the fluoroscopic procedure. Nursing staff may be present to assist during fluoroscopic procedures, depending on the condition of the patient and whether medication administration is necessary. Mini-C-arms have clinical applications outside the hospital, and thus may be used in medical emergencies at sporting events, and in sports medicine and physical therapy facilities.
Training
Use of a fluoroscope requires training in radiographic and fluoroscopic principles and techniques. X-ray technologists should have completed appropriate educational programs (registered technologist programs). Any staff using fluoroscopic equipment should participate in clinical training provided by the equipment manufacturer.
BOOKS
Dendy, P.P., and B. Heaton. Physics for Diagnostic Radiology, 2nd edition. Philadelphia, PA: Institute of Physics Publishing, 1999.
PERIODICALS
Aliabadi, D et al. "Rapid Bedside Coronary Angiography with a Portable Fluoroscopic Imaging System." Catheterization and Cardiovascular Diagnosis 41, no.4 (August 1997): 449-55.
Hernandez, R. J., and M. M. Goodsitt. "Reduction of
Radiation Dose in Pediatric Patients Using Pulsed Fluoroscopy." American Journal of Roentgenology 167, no. 5 (November 1996): 1247-53.
ORGANIZATIONS
American College of Radiology. 1891 Preston White Drive, Reston, VA 20191-4397. (800) 227-5463. <http://www.acr.org>.
American Registry of Radiologic Technologists. 1255 Northland Drive, St. Paul, MN 55120-1155. (651) 687-0048. <http://www.arrt.org>.
American Society of Radiologic Technologists (ASRT). 15000 Central Avenue SE, Albuquerque, NM 87123-2778. (800) 444-2778. <http://www.asrt.org>.
