1-11. USE OF TELEVISION
Current fluoroscopic equipment displays the patient under fluoroscopy. The use
of television (TV) is an integral part of the fluoroscopic system. Television offers more
convenience and mobility for viewers, biplane viewing, and the advantage of video
1-12. VIDEOTAPE RECORDING
a. Videotape recording is a means of electronically recording the fluoroscopic
image. In contrast to cine, which uses the photographic process to record the image on
film, a videotape recorder uses magnetic tape.
b. In the recording phase of operation, the video signal produces a varying
magnetic field at the recording head, which imprints the signal information on the
magnetic tape. In the playback phase, the information on the tape is converted back
into a video signal that is displayed on a monitor much the same as the original signal.
Videotape recording offers several advantages over cine recording. Among them are
lower radiation dose to the patient, no processing, instant playback, and the reusability
of the tape. The major disadvantage is that resolution is somewhat lower than with
cine. Consequently, videotape may not be practical when high resolution is required.
However, since instant playback is possible with videotape, it can be used in addition to
cine to determine if the information recorded on the cine film is adequate. Using
videotape as back-up device in this manner eliminates the necessity of having the
patient remain in the radiology department until the cine film is processed.
Section II. SPECIAL TECHNIQUES AND EQUIPMENT
1-13. IMAGE INTENSIFICATION
Image intensification relates to a method of producing fluoroscopic images
characterized by a high level of brightness. The light gain of an x-ray image intensifier
may be defined as the ratio of brightness on the apparatus to the brightness of a
standard fluorescent screen, both excited by the identical intensity of radiation. One of
the uses of an image intensifier is for doing cinefluorography.
1-14. PRINCIPLES OF IMAGE INTENSIFICATION
a. The basic component use for effecting image intensification is essentially a
type of electronic tube (figure 1-4) used in conjunction with an x-ray source, an electrical
energizing and controlling system, and an optical system.