What Scoliosis X-Rays Show

Low-dose systems such as EOS use much less radiation than standard X-rays.

What views are taken?

The core images are full-length standing X-rays from the back (posteroanterior, or PA) and from the side (lateral). Taking the front view from the back reduces radiation to the breasts and thyroid. Bending or flexion–extension images may be added to check flexibility or instability. At my practice, this means full-spine standing X-rays.

What is the Cobb angle?

The Cobb angle measures the size of a sideways curve. Lines are drawn along the most tilted vertebrae at the top and bottom of the curve, and the angle between them is measured. A curve over 10 degrees is defined as scoliosis.

Measurements naturally vary. The same reader can differ by 3–5 degrees, and two different readers by 5–7 degrees. That is why a change of 5 degrees or more is generally needed to call a curve "worse."

What does the side view show?

The side view shows sagittal (front-to-back) alignment, which often matters more for symptoms than the sideways curve. Key measurements include:

• How far the trunk sits forward of the pelvis
• The shape of the pelvis (pelvic incidence)
• How much the pelvis is tilted back

See Pelvic incidence and Sagittal balance.

Why image the hips and knees?

When the spine tips forward, the pelvis and knees compensate. A spine-only image can miss this and make alignment look better than it is. Dr. Diebo's group developed the global sagittal axis, which measures posture from the knees to the neck. It correlated strongly with patients' quality of life.

What is EOS imaging?

EOS takes front and side images at the same time while you stand, and it can create a 3D model of your spine. Its standard setting uses about 50–80% less radiation than conventional X-rays. Its "micro-dose" setting can be dozens of times lower, which suits repeated follow-up scans. EOS is available at our Kettle Point office.

How much radiation is involved?

Typical effective doses for a full-spine study are:

• Conventional digital X-ray: about 0.07–2.7 mSv
• EOS standard dose: about 0.09–0.22 mSv
• EOS micro-dose: about 0.003–0.017 mSv

Will I need an MRI or CT?

An MRI is used when nerve symptoms suggest pinched nerves. A CT is used for surgical planning, to check whether a fusion has healed, or to estimate bone strength.

Tips for your appointment

• Bring prior X-rays (images, not only reports) so changes can be compared
• Stand in your natural posture. Don't try to "stand up straight" for the picture.

When to see a specialist. Need a full-length imaging review or second opinion? Request an appointment.

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