c. Time (duration of exposure) should be kept at a minimum compatible with the
completion of the examination. TB MED 521 requires that a manual reset, 5-minute
cumulative timing device be used to indicate elapsed time of exposure and to "turn off"
the tube energizing circuit at the end of 5 minutes.
d. The size of the field should be kept at a minimum to decrease the amount of
e. The dose rate measured in the CR at tabletop will not exceed 10 roentgens
per minute (R/min) for fluoroscopic equipment with automatic exposure control, except
during cinefluorographic and spot films. Equipment without automatic exposure control
will not exceed 5 R/min.
f. Lead gloves and apron will be worn by the radiologist and by the specialist,
who must remain close to the unit to perform his work. The lead equivalent of the apron
and gloves will be at least 0.5 mm to 0.25 mm measured at 80 kVp. Lead shields
between the sources of radiation and the staff serve the same purpose.
g. Structural shielding for radiographic/fluorographic installations should include
1/16-inch lead or equivalent material to a wall height of 7 feet. (Note: fluoroscopic
installations only require 1/32 inch lead or equivalent material.)
h. Equipment will comply with the safety provisions of TB MED 521.
i. The fluoroscopic equipment should be operated only by a medical officer of
the department of radiology or by a medical officer properly trained and authorized by
the radiologist in charge to conduct fluoroscopic examinations.
a. During the fluoroscopic study of gastrointestinal physiology, it is often
desirable to record a particular finding on film. This finding may be transitory and
capable of visualization only while the patient is in a limited number of positions. For
such occasions, it is practical to expose a film quickly and without changing the position
of the patient. To provide for such exposures, a spot-film device is utilized. As shown
in figure 1-2, the cassette loaded with film is stored in a lead shielded area of the spot-
film device. The shielded tunnel arrangement is mounted on the backside of the
radiographic table. The moment the pertinent view is located, the examiner releases
the foot (or thumb) switch and actives the spot-film exposure button. When the spot-film
exposure button is activated, the spot-film device acquires the cassette and brings it into
position in over the central ray. During this action, the radiographic tube under the table
switches from fluoroscopy to spot-exposure mode. This action happens automatically
and the device returns the cassette to the shielded storage area until the button is