b. In another method (referred to as the "single-stage method"), the air is
introduced into the colon at the instant the column of the radiopaque contrast material
has advanced to predetermined area in the colon.
(1) After patient preparation, ready the necessary facilities for the
examination. With the patient in the prone position on the x-ray tilt-table, the radiologist
observes the advance of the radiopaque column of contrast material in the colon. This
is done under fluoroscopic control. The barium suspension is allowed to run slowly.
When the head of the column reaches the splenic flexure, the flow is immediately
(2) The x-ray table is then tilted to the Trendelenburg or modified
Trendelenburg position and the patient is rotated to the left.
(3) Insufflation of air is begun. The transport of the barium-suspension
column is studied fluoroscopically as the air pushes it onward in the colon. The patient
is now rolled onto his back and turned to the right as far as directed by the radiologist.
This maneuver allows the barium suspension to flow toward the hepatic fissure and
enter the ascending and cecal portions of the colon. Spot-films are made as indicated.
Usually, as the contrast medium reaches the hepatic fissure, the air input is closely
controlled and the tilt-table may be brought to the horizontal or the head-end may be
slightly elevated to permit filling of the cecum. Further distribution of the contrast
material in the colon is carried out (under fluoroscopic control) by rotating the patient,
when necessary, as much as 360 in either direction.
(4) After completion of the fluoroscopic phase of the examination, the outlet
tubing is clamped off and radiography is done according to established procedure. This
procedure may be performed as follows.
(a) PA and AP (anterior-posterior) projections are made using a
vertical CR with the patient in the horizontal position.
(b) PA or AP projections are usually made with the patient in the right
and left lateral decubitus positions using a horizontal CR.
(c) For optimum results, a minimum of 90 kVp (kilovolt peak) (based on
8 to 1 Potter-Bucky diaphragm) should be used. Grid-front cassettes may be found
extremely useful for making the exposure with the patient in the lateral decubitus
(d) The AP axial projection is sometimes done during single contrast
studies using a 30-40 degree tube angle. It is made according to established