d. Projections. The projections to be made for angiocardiography are
determined by the examiner and will depend upon the nature of the given case. The
specialist is concerned about the exact order and specific time the required films are to
be exposed and, in the case of the obliques, also the degree of rotation to be used. As
a rule, when rapid-sequencing recording apparatus in combination with a biplane
exposure setup is used, simultaneous AP and lateral projections only are made.
e. Injection of Contrast Medium and Radiography.
(1) When everything is in complete readiness, participants alerted, x-ray unit
turned on, technique factors selected, and the tube anode actuated to "exposure-
rotation." the examiner draws about 10 to 15 cc of blood from the patient's vein into the
syringe.
(2)
The examiner instructs the patient to suspend respiration at the end of
exhalation.
(3)
Next, the patient is told to inspire rapidly and deeply and then to hold his
breath.
(4) Simultaneously with the inspiration, 40 to 50 cc of the contrast solution is
injected at a rate of about 25 to 35 cc per second. At the exact instant the injection is
begun, the specialist starts the stopwatch.
(5) With his eyes on the stopwatch and his hand on the exposure controls,
the specialist makes the first exposure at the predetermined instant.
(6)
Additional exposures are made as ordered by the examiner.
f. Radiographic Technique Factors.
(1) The kVp is usually increased 10 percent over other exposures of the
same par, and the mA adjusted to hold density constant.
(2)
Special consideration should be given to the following:
(a) Exposure time. Due to the relatively rapid transport of the contrast
medium in angiocardiography, the shortest practicable exposure time should be used.
Exposure time for the average adult patient should not exceed 1/15 second. For a
small child, it should not exceed 1/30 second. Under average conditions, exposure
times of 1/30 second for the adult patient and 1/60 second for the small child patient are
usually adequate. When allowed a choice, it may be preferable to use exposure times
shorter than those given above.
MD0959
3-27
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