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Scoliosis is an abnormal lateral curvature of the vertebral column and affects approximately 2 percent of the population. Although scoliosis runs in families, it’s idiopathic  in the vast majority of cases, meaning that the cause is unknown.

It usually develops in middle or late childhood, before puberty, and is seen more often in girls than boys. In adults, scoliosis may represent the progression of a condition that actually began in childhood, and was not diagnosed or treated.

Currently, scoliosis is treated successfully by special braces, electrical stimulation, surgery, or by combinations of these three techniques. Most scoliosis cases can be treated nonoperatively, especially if they are detected before they become too severe. However, 60 percent of curvatures in rapidly growing prepubertal children will progress; generally, curvatures less than 30 degrees will not progress after the child is skeletally mature.

However, with greater curvatures, it may progress at about 1 degree per year in adults. If scoliosis is neglected, the curves may progress dramatically, exceeding 45 degrees to 50 degrees, and creating significant physical deformity and even cardiopulmonary problems.

Before any treatment begins, medical professionals will often assess the degree of scoliosis by radiographic imaging. This assessment can be made by posteroanterior (PA) upright, lateral upright and PA and lateral bending studies. The bending studies can be used to differentiate structural from nonstructural curves. The routine, however, is a PA and lateral erect image of the entire spine.

PA Scoliosis

Scoliosis is often diagnosed in the teenage girls. Radiation protection and tight collimation is, therefore, vitally importantly to avoid unnecessary exposure or scattered radiation to the gonads and breasts. Anteroposterior (AP) imaging is not recommended because the breast would be subject to radiation from the primary beam.

Ideally, one exposure is taken using a 14-inch x 36-inch (35-cm x 90-cm) image receptor (IR). Compensating filters are recommended to even out the exposure due to the wide range of thickness, from the upper thoracic to the lower lumber vertebrae. A 60-inch (152-cm) source-to-image receptor distance is recommended.

The patient should be standing straight with the IR adjusted to include about 1 inch of the iliac crest. Patients should be relaxed with arms hanging at the sides. The central ray is directed to the midpoint of the IR.

The PA projection should demonstrate the entire thoracic and lumbar spine, including about 1 inch of the iliac crest.

Lateral Scoliosis

The patient is adjusted to the lateral with the midsagittal plane parallel to the IR and the midcoronal plane centered to the midline of the IR. The central ray is directed to the midpoint of the IR.

The radiograph should demonstrate no rotation of the vertebral column. Also, the posterior margins of the vertebral bodies should be superimposed and the ribs superimposed posteriorly.


References:
Tortora FJ, Derrickson B. Principles of Anatomy and Physiology. Hoboken, NJ: John Wiley & Sons, Inc; 2003.

Ballinger PW. Frank ED. Merrill’s Atlas of Radiographic Positioning and Radiologic Procedures. 10 Ed. St Louis, MO: Mosby; 2003.
 

— Olive Peart, MS, RT(R)(M), is the clinical instructor of the radiology program at Stamford Hospital in Connecticut, as well as an editorial consultant for and regular contributor to RT Image. Questions and comments can be directed to editorial@rtimage.com.