LEFT ANTERIOR OBLIQUE | BARIUM ENEMA

Wednesday, September 24, 2014

Pathology Demonstrated:

  • Obstruction, including ileus, volvulus, and intusseception, often are demonstrated, Double-contrast media barium enema is ideal for demonstrating diverticulosis, polyps, and mucosal changes.

Technical Factors:

  • Image receptor size - 35 x 43 cm (14 x 17 inches), lengthwise
  • Moving or stationary grids
  • 100 to 125 kV range single-contrast study
  • 90 to 100 kV range for double-contrast study
  • 80 to 90 kV range for iodinated, water soluble contrast media.
  • mAs 4

Shielding:

  • Place lead shield over gonads only if possible without covering pertinent anatomy.

Patient Position:

  • Patient is semiprone, rotated into a 35° to 45° left anterior oblique, with a pillow for the head.

Part Position:

  • Align MSP along long axis of table, with right and left abdominal margins equidistant from center line of table and CR.
  • Place right arm up on pillow, with left arm down behind patient and right knee partially flexed.
  • Check posterior pelvis and trunk for 35° to 45° rotation.

Central Ray:

  • CR is perpendicular to IR, directed to a point about 1 inch or 2.5 cm to the right of MSP.
  • Center CR and IR to 1 to 2 inches (2.5 to 5 cm) above iliac crest. see note.
  • Center cassette to central ray.
  • Minimum SID is 40 inches (100 cm)

Collimation:

  • Collimate on four sides to outer margins of IR.

Respiration:

  • Suspend respiration and expose on expiration.

Note: Most adult patient requires about 2 inches (5cm) higher centering to include the left colic flexure, which generally cuts off the lower large bowel: then a second image centered 2 to 3 inches (5 to 75 cm) lower is required to include the rectal area.

Radiographic Criteria:

Structure Shown:

  • The left colic flexure should be seen as open without significant superimposition.
  • The decending colon should be well demonstrated.
  • The entire large intestine should be included (see notes)

Position:

  • Spine is parallel to the edge of radiograph (unless scoliosis is present). Ala of right ilium is elongated if visible, whereas the left side is foreshorted and the left colic flexure is seen in profile.

Collimation and CR:

  • Only minimal collimation margins seen on all four sides for adults.
  • CR is centered at level of iliac crest  to include entire left colic flexure.

Exposure Criteria:

  • Appropriate technique should visualize the contrast-filled large intestine without significant overexposure of any portion.
  • Sharp structural margins indicate no motion.

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