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
 |
| 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
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.
1 comment:
Scoliosis is an abnormal alignment of the spine which can be seen in most age groups. Some degree of Scoliosis occur in 2-3% of children younger than 16 years old. Most people with scoliosis less than 10 degrees do not require treatment.
Post a Comment