RIGHT ANTERIOR OBLIQUE POSITION : BARIUM ENEMA

Sunday, March 16, 2014

BARIUM ENEMA | RAO POSITION


Pathology Demonstrated:

  • Obstructions, including ileus, volvulus, and intussuception, often are demonstrated.
  • Double Contrast media barium enema is ideal for demonstrating diverticulitis, polyps, and mucosal changes.

Technique Factor use for RAO Position:

  • IR size 35 x 43 or 14 x 17 inches, lenghtwise
  • Moving or stationary grid
  • 90 to 100 kV range for Double Contrast Study
  • 100 to 125 kV range for Single Contrast Study
  • 80 to 90 kV range for iodinated, water soluble contrast media.
  • mAs 4

barium enema
RAO Barium Enema

Shielding of Patient when Taking RAO Position:

  • Shield gonads only if this is possible without covering pertinent anatomy.

Patient Position:

  • Patient is semiprone, rotated into a 35 to 45 degree right 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 or CR.
    Place left arm up on pillow, with right arm down behind the patient and left knee partially flexed.
  • Check posterior pelvis and trunk for 35 to 45 degree rotation.

Central Ray:

  • Direct CR perpendicular to IR to a point about 1 inch (2.5 cm) of the left of the MSP.
  • Center central ray and image receptor to level of iliac crest (see note).
  • Minimum SID is 40 inches (100 cm)

Collimation:

  • Collimate to outer margin of IR.

Respiration of Patient on RAO:

  • Suspend respiration and expose on expiration.

Note:
Ensure that ampulla is included on lower margin of IR. This action may require centering 1 to 2 inches below the iliac crest on larger patients and taking a second image centered 1 to 2 inches above the iliac crest to include the right colic flexure.

Radiographic Criteria for Right Anterior Oblique RAO:


Structure Shown:

barium enema
RAO Position Barium Enema
  • The right flexure and the ascending and sigmoid colon are seen ''open" without significant superimposition.
  • The entire large intestine is included, with the possible exception of the colic flexure, which is best demonstrated in Left Anterior Oblique LAO position. (or may required a second image centered higher).
  • The rectal ampulla should be included on the margin of the radiograph.

Position:

  • The spine is parallel to the edge of the radiograph (unless scoliosis is present)
  • The ala of the right ilium is foreshortened, and the left side is elongated; the right colic flexure is seen in profile id included.

Collimation and CR:

  • Only minimal collimation margins are seen on all four sides for adults.
  • CR is centered at the level of the iliac crest.

Exposure Criteria:

  • Appropriate technique should visualize the entire air and barium filled large intestine without overexposing the mucosal outlines of those sections of primary air filled bowel on a double contrast study.
  • Sharp structural margins indicate no motion.

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