SCOLIOSIS SERIES X-RAY EXAM IN AP or PA Projection

Sunday, October 19, 2014

Pathology Demonstrated when taking scoliosis series in AP or PA:

  • Degree and severity of scoliosis are shown.
  • When taking scoliosis series it is usually taken two AP or PA images for comparison one is in erect position and one is in recumbent patient position.

Technical Factors:

  • Image receptor size is 14 x 17 inches or 35 x 43 cm, cassette is in lengthwise, for taller patients use 35 x 90 cm cassette if available.
  • Moving or stationary grid
  • Compensating filters to obtain a more uniform density along the vertebral column.
  • kV is appropriate for patient size/age, to provide an image of optimal contrast and make patient dose or exposure low.
  • If patient is in erect position use erect makers.
  • SID is 60 inches or 152 cm.
  • If taken in PA use kV 90, mAs 25
  • AP kV 90, mAs 25
Scoliosis series PA projection
PA Projection

Shielding:

  • Shield gonadal region without obscuring area of interest. for younger patients use breast shield. Shadow shield placed on collimator may be used.

Patient Position:

  • The patient position may be erect or recumbent position, and weight evenly distributed on both feet for the erect position.

Part Position:

  • CR and midline of cassette is align to midsagittal plane, with arms at side.
  • Ensure no rotation to torso or pelvis if possible.
  • Scoliosis may result in twisting and rotation of vertebrae, making some rotation unvoidable.
  • Place lower margin of IR a minimum of 1 to 2 inches (3 to 5 cm) below iliac crest. (centering height determined by IR size and or area of scoliosis.

Central Ray:

  • CR perpendicular, directed to midpoint of IR
  • SID of 40 to 60 inches (100 to 150 cm) or longer SID required.
  • with larger IR to obtain required collimation
  •  

Collimation:

  • Collimate on four sides to area of interest. Too narrow a collimation is not recommended on initial image because deformities of adjacent areas of ribs and pelvis also must be evaluated.

Respiration:

  • Suspend breathing on expiration.

Note: A PA rather than an AP projection is recommended because of the significantly reduced dose to radiation-sensitive areas, such as female breast and the thyroid gland. Studies have shown that this projection results in approximately 90% reduction in dosage to the breast.
Scoliosis generally requires repeat examination; over several years for pediatric patients, with emphasis on the need for careful shielding.

Radiographic Criteria in Scoliosis Series AP or PA

Scoliosis

Structure Shown:

  • The lumbar and thoracic vertebrae, as well approximately 2 inches (5cm) of the iliac crest.

Position:

  • Thoracic and lumbar vertebrae are demonstrated in as true an AP projection as possible.
  • Some rotation on pelvis and thorax may be apparent because scoliosis generally is accompanied by twisting or rotation of involved vertebrae.

Collimation and CR:

  • Sufficient density and contrast should demonstrate the thoracic and lumbar vertebrae in their entity.
  • A compensating filter assists in obtaining an even density throughout the length, if a 14 x 36-inch (35 x 90 cm) image receptor is being used.
  • Sharp bony markings indicate no patient motion.

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