Explained: How a bone density scan works and why they’re used

Bone-related health problems become more frequent as we age, making a bone density scan necessary. So what is involved with the procedure? Are there any costs involved?

A bone density scan is medical procedure that determines the density of your bones – that is, the thickness and strength of the minerals that make up your bones.

There are a number of different procedures that can reveal your bone density, all with varying costs.

It’s possible to get a bone density scan with or without a referral from your GP, but only those with a note from a doctor will be eligible for government assistance under the Medicare Benefits Scheme (MBS), and even then only for certain conditions. More on that later.

Why get a bone density scan?

Whichever procedure you’re having, a bone density scan can provide an early warning for conditions such as osteoporosis, which is characterised by a major loss of bone density and strength, causing bones to become brittle and break more easily.

A bone density scan can also reveal the slightly less serious osteopaenia (minor bone density loss), spinal fractures or deformities or even cancer. Bone density scans are usually conducted by a radiographer.

However your bone density is measured, it will be reported as a value given in grams of material per centimetre of bone squared, or g/cm2, and you’ll also be given a T-score and a Z-score for reference.

These scores describe your bone density in relation to other people. The T-score represents your bone density versus that of young adults of the same gender. The Z-score is your bone density versus people of the same age and gender.

Generally, osteoporosis will be diagnosed if your T-score is -2.5 or less.

Since osteoporosis and other bone conditions are more common in older people, particularly women, a bone density scan may be something your doctor recommends in the near future.

Bone density scan types

There are three main types of bone density scans a doctor may order: dual energy X-ray absorptiometry (DEXA), single energy X-ray absorptiometry (SEXA) and ultrasound.

DEXA – This is the most common method used to measure bone density as it is fast and accurate. A specialised X-ray machine passes X-ray beams of different energies through the body while the patient lies on a flat bed.

The differing X-ray beams measure bone and soft tissue separately and can be used to measure the total skeleton if needed.

SEXA – This procedure uses a single X-ray beam of only one energy frequency, rather than the dual frequencies of DEXA. In this technique, the area to be tested is often wrapped in a tissue-like substance or immersed in water to improve the quality of the results.

It is mainly used to measure bone density in specific peripheral sites of the body such as your forearm or heels.

Ultrasound – Scans using ultrasound are used to get a more detailed look at the structural integrity of your bones. Ultrasound scans can be useful in identifying problems associated with acute pain in a particular area.

What are the costs?

A bone density scan, without any government rebate, will set you back anywhere between $80 and $200, depending on the radiographer.

But there is a government rebate available under the MBS for a bone density scan measuring two or more sites on your body, if you have a referral from your doctor for one of the following reasons:

• people with diagnosed osteoporosis
• anyone with one or more previous fractures from a minor incident
• corticosteroids use (common for asthma)
• women with early menopause
• men with low testosterone
• individuals with coeliac disease (or other malabsorption conditions), overactive thyroid or parathyroid conditions, rheumatoid arthritis, liver or kidney disease
• prolonged glucocorticoid therapy
• any condition associated with excess glucocorticoid secretion
• male hypogonadism or female hypogonadism lasting more than six months before the age of 45
• chronic liver disease
• chronic renal disease
• malabsorption conditions.

This means that depending on the radiographer you use, the procedure may be totally covered by the rebate. Depending on your condition, you are eligible to claim this rebate once every 12 months, or once every two years.

Changes to the MBS in 2017 granted everyone aged 70 and over access to an additional screening scan that doesn’t require a referral from your GP.

Have you had a bone density scan? Did you have any out-of-pocket costs? Let us know in the comments section below.

Read: Seven surprising things you can do to help build bone density