Which Test is the Best?

Several tests are available to determine bone density:

  1. X-Rays
  2. Heel Ultrasound
  3. Quantitative Computed Tomography (QCT)
  4. Single Energy X-Ray Absorptiometry(SPX) and Peripheral Dual Energy X-Ray Absorptiometry (pDEXA)
  5. Dual Energy X-Ray Absorptiometry (DEXA)


X-Rays are unable to detect osteoporosis and are only suggestive of a reduced bone mass (osteopenia). Often a significant bone loss needs to occur (up to 30%) before osteopenia is detected.

Heel Ultrasound

The heel ultrasound test measures the speed of sound through the calcaneum as well as attenuation of the sound wave. Together these measurements can give an indication of the bone stiffness. This method is generally used as a pre-screening tool for osteoporosis. However, it is not a definitive bone density assessment and cannot be used for follow-up testing or monitoring therapy.

Quantitative Computed Tomography

This is a unique test in that it calculates a volumetric or 3D measurement of bone density of trabecular bone within the vertabrae. However, it has lower precision and accuracy and higher radiation doses to the patient and a higher cost compared to the DEXA test.

Single Energy X-Ray Absorptiometry and Peripheral DEXA

These tests are able to measure the bone density of peripheral sites only - such as forearm, finger and sometimes the heel.

Dual Energy X-Ray Absorptiometry

The DEXA test measures the amount of calcium in the bones of both central (hip and spine) and peripheral (forearm) sites. Within the X-Ray beam are two distinct energy intensities that differentiate bone from soft tissue.

Bone density test

Fractures of the hip and spine are the most common locations for osteoporotic fractures. Therefore measurement of these two sites is preferable for determining a baseline reading and for serial follow-up measurements. The DEXA test is considered to be the "gold standard" when diagnosing osteoporosis.

The DEXA test has greater precision than the other tests, short scan times and lower radiation doses. The exposure to radiation for the patient for each DEXA test is approximately 1/10 of a standard chest X-Ray.

Only a DEXA scan of two skeletal sites attracts a Medicare rebate for eligible patients [see Medicare rebates].