b. Type of Equipment Used for Indirect Radiography or Photofluorography.
For this method, digital subtraction images are captured and the x-ray unit is equipped
with a digital image intensifier.
c. Tube Heat Capacity. This factor is of prime importance in angiography,
especially when it is necessary to make rapid-sequence exposures of very short
duration (1/30 sec (second) or less) and relatively high energy levels. Tube and
generator capacities from 300 to 1200 mA are commonly used in angiocardiographic
examinations. When relatively high milliamperage values are used, careful
consideration must be given to the appropriate tube-rating chart. For example, if the
tube-rating chart stipulates an upper limit of 1/10 second exposure time at 500 mA and
100 kVp, this would permit six rapid-sequence exposures at 1/60 second, or three such
exposures at 1/30 second. This means that the sum of any serialized increments of
exposure time (in rapid sequence) is not to exceed the safe limits stipulated in the tube-
rating chart for the given mA-kVp value. Where it is not feasible to use the upper range
of mA values, the lower mA values, with compensatory increase in kVp, may be used.
d. Accessory Devices.
(1) Grid-front cassettes or tape-on grid mounted on a movable stand that
can be adjusted.
(2) Protective devices especially designed for, or easily adaptable to, the
particular needs of the given situation, such as leaded shields, lead-impregnated gloves
and aprons, and thyroid shields. These items are required for the protection of all
(3) Special timing and sequencing device (or program selector). This may
consist of a thyraronic rapid-recovering timing unit or a timing unit that embodies a type
of high-voltage switch, tube, and condenser arrangement. These devices are used for
making exposures of 1/1000 to 1/500 second in rapid sequence at predetermined
intervals. They are especially suited for serialized studies showing the progressive
phases of the transport of the opacifying agent through specific portions of the vascular
system (for example, the various chambers of the heart or the great vessels).
(4) Immobilization and supportive devices, such as bands and straps,
clamps, bags filled with sand or shot, folded towels, adjustable stools, and foot and