FLUOROSCOPIC AND SPECIAL RADIOGRAPHIC EQUIPMENT
Section I. FLUOROSCOPY
a. Fluoroscopy is one of two general methods of radiographic examination by
which an image is produced on the fluorescent screen when the part to be examined is
interposed between the energized tube and the fluoroscopic screen. One great
difference between the fluoroscopic image and the conventional radiographic image is
that the former persists only during x-ray excitation of the screen, thereby permitting
only limited time for examination, whereas the latter is a permanent record that can be
studied at leisure. Another difference is that in the fluoroscopic image the dense
portions of the part under examination appear as dark areas on the screen and the
radiolucent portions as light areas whereas the reverse is true of the radiographic
image. For instance, the lungs would appear lighter than the heart in a fluoroscope
examination but in a radiograph, they would look darker.
b. Fluoroscopy permits observation of gross physiology, which is that physiology
concerned with motion of the heart, diaphragm, and alimentary tract; transport of
contrast media through the alimentary tract; and so forth. The great value of
fluoroscopy lies in the opportunity for correlation of anatomy and physiology, normal or
abnormal. Added value accrues through the ready alteration of the patient's position
under fluoroscopic observation. This serves to localize an abnormality in relationship to
other structures and to establish which positions will be advantageous in radiography.
Furthermore, procedures such as progressive filling of sinus tracts or the bronchial tree
with contrast medium may be guided fluoroscopically to ensure that films will be
exposed at the proper time (that is, neither incomplete outlining nor overfilling).
The principal components (in addition to generator, controls, etc.) required for the
production and management of the fluoroscopic image are as follows:
a. X-ray Tube. The x-ray tube is usually located under the table and is attached
to the fluoroscopic tower. It is the source of x-rays for excitation of the fluoroscopic
equipment. The National Committee on Radiation Protection and Measurements and
TB MED 521 specify that the tube-tabletop distance will be not less than 15 inches (38
cm). TB MED 521 further specifies that the total permanent filtration in the useful beam
shall be at least 2.5 mm aluminum equivalent.