Tuesday, October 21, 2014

Pathology Demonstration:

  • Projection is used to asses mobility at a spinal fusion side.
  • Two images are taken with the patient in the lateral position, - one in hyperflexion and hyperextended.
    Right and left bending positions also are generally part of a spinal fusion series and are the same as for the scoliosis series.

Technical Factors:

  • Film size - 35 x 43 cm (14 x 17 inches)
  • Stationary or moving grid.
  • 85 to 95 kV range, and put lead mat behind patient if recumbent.
  • Extension and flexion markers.
  • mAs 50


  • Place lead contact shield over gonads without obscuring area of interest.

Patient Position:

  • Position patient in lateral recumbent position, with pillow for head and support between knees. (see notes if patient is in erect position.)
  • Place lower edge of IR 1 to 2 inches, below the iliac crest.

Part Position:

  • The midcoronal plane is align in the center of the grid.

Hyperflexion Positioning:

  • Using pelvis as fulcrum (pivot point), let patient to assume fetal position (bending forward) and draw legs up as far as possible.

Hyperextension Positioning:

  • Using pelvis as fulcrum, ask patient to move torso and legs posteriorly as far as possible to hyperextend long axis of body.
  • Ensure that no rotation of thorax or pelvis exists.

Central Ray:

  • Direct CR perpendicular to IR.
  • Center CR to site of fusion if known or to center of IR.
  • SID is 40 inches.

Spinal fusion series hyperflexion
Hyperflexion lateral


  • Four - sided collimation to area of interest.


  • Suspend breathing on expiration.

Notes: Projection also may be done with patient standing erect or sitting on a stool, first leaning
forward as far as possible, gripping the stool legs, then leaning backward as far as possible, gripping the back of the stool to maintain this position.
The pelvis must remain as stationary as possible during positioning. The pelvis acts as a fulcrum (pivot point) during changes in position.

Radiographic Criteria Spinal Fusion Series:

Structure Shown:

Spinal Fusion series hyperextension radiograph
  • A lateral view of the lumbar vertebrae in hyperflexion and hyperextension.


  • True lateral position of patient is indicated by superimposed posterior vertebrae bodies.

Collimation and CR:

  • Vertebral column and contrast clearly demonstrate lumbar vertebrae and intervertebral joint spaces.
  • Sharp bony margins indicate no motion.

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