A nuclear medicine bone scan uses a small radioactive tracer to highlight areas of unusual bone activity — which can mean a fracture (including small stress fractures), infection, arthritis, or cancer that has spread to bone. Because it scans the whole skeleton in one go, it's very good at finding where a problem is. It gives about 5 mSv of radiation, involves a wait between the injection and the pictures, and is painless.
Key takeaways
- A bone scan highlights areas of increased (or decreased) bone activity.
- Used for unexplained bone pain, fractures, infection and cancer spread.
- It scans the whole skeleton at once, then a specific area can be examined closely.
- It gives about 5 mSv; drinking water afterwards helps clear the tracer.
A bone scan is one of the most useful nuclear medicine tests. It doesn’t show the bones’ shape the way an X-ray does — instead, it shows how active different parts of the skeleton are, which can reveal problems an X-ray misses.
How it works and what it shows
You’re given a small radioactive tracer (technetium-99m), which is taken up by areas of the skeleton that are busy repairing or reacting to something.[1] On the images, these show as “hot spots” of increased activity.
A bone scan is useful for:[1]
- Fractures — including small or stress fractures that may not show on X-ray
- Infection in the bone
- Arthritis and other joint problems
- Cancer that has spread to the bones (metastatic bone disease), and bone tumours
- Unexplained bone pain
Its big advantage is that it scans the whole skeleton in one go, so it’s excellent at finding where a problem is — after which a more detailed test (X-ray, CT or MRI) can examine that exact spot.[1]
What to expect
After the tracer is injected, there’s usually a wait of a few hours while it travels to and collects in the bones; you may be able to leave and come back.[1] You’ll be asked to drink plenty of fluids (which also helps lower the dose), and the pictures themselves — taken with a gamma camera, sometimes as a 3D SPECT-CT — are painless.
The radiation
A bone scan gives about 5 mSv of radiation — in the range of other higher-dose imaging, and roughly a few years of natural background radiation.[3] The benefit of finding the problem usually outweighs this small risk. Tell the team if you are, or might be, pregnant or breastfeeding.
Frequently asked questions
How much radiation is in a bone scan?
About 5 mSv — similar to other higher-dose imaging. The benefit of finding a fracture, infection or cancer spread usually outweighs the small risk.[3]
Why is there a wait before the pictures?
The tracer needs a few hours to travel to and collect in the bones; the camera then takes the images. You can often leave and return.[1]
Is a bone scan the same as a DXA (bone density) scan?
No. A nuclear medicine bone scan shows bone activity (fractures, infection, cancer); a DXA scan measures bone density for osteoporosis and uses a far lower dose. They’re different tests.[1]
Sources
- RadiologyInfo.org (RSNA & ACR) — General Nuclear Medicine (bones) — www.radiologyinfo.org/en/info/gennuclear
- RANZCR / InsideRadiology — Nuclear medicine (Cain) — www.insideradiology.com.au/nuclear-medicine/
- ARPANSA — Nuclear medicine and radiation doses — www.arpansa.gov.au/understanding-radiation/radiation-sources/more-radiation-sources/medical-imaging
