DEXA Scan: Is It Safe And What Is The Procedure?

Dual-energy X-ray absorptiometry (DEXA) is widely regarded as the gold standard for measuring bone density and body composition. Its precision, accuracy, and low radiation dose make it an essential tool in both clinical and sports settings. DEXA scans provide detailed insights into bone health, fat distribution, and muscle mass, offering valuable information for diagnosing osteoporosis, assessing fracture risk, and monitoring athletes’ body composition.

DEXA uses two X-ray beams at different energy levels to create detailed images of the body. These beams pass through the bones and soft tissues, and the DEXA machine measures the absorption of each beam by the tissues. The difference in absorption rates between the two beams allows the machine to calculate bone mineral density (BMD) and differentiate between bone, fat, and lean tissue. This method provides highly accurate and reproducible measurements, making it a reliable tool for medical and sports applications.

DEXA scans are considered very safe due to the minimal radiation exposure involved. The procedure is non-invasive and typically completed within 10 to 20 minutes. While the radiation dose is extremely low, any exposure to radiation carries a small potential risk. However, for most patients, the benefits of obtaining precise information about bone density and body composition far outweigh these minimal risks.

The effective dose from a single whole-body DEXA scan ranges between 2 and 10 microsieverts (µSv). To put this into perspective, the annual natural background radiation in the UK is approximately 1,000 µSv. A DEXA scan’s radiation dose is significantly lower than that of a chest X-ray (about 14 µSv) and vastly lower than a CT scan of the trunk, which can range from 6,000 to 10,000 µSv.

Given its low radiation dose, DEXA scans can be safely performed multiple times per year if medically justified. However, it is crucial to consult with a healthcare provider to determine an appropriate schedule based on individual health needs.

During a DEXA scan, the patient lies on a padded table while the scanner passes over the body. The patient must remain still to ensure clear and accurate images. The procedure is painless and typically takes between 10 and 20 minutes. Patients may be asked to wear a hospital gown and remove any metal objects, such as jewelry or belts, which can interfere with the scan. The results are usually available shortly after the scan and are reviewed by a healthcare provider.

While DEXA scans are safe for most people, certain individuals should avoid them. Pregnant women are advised against undergoing DEXA scans due to the potential risk to the developing fetus. Individuals who have recently undergone other imaging procedures that involve barium or contrast material should inform their healthcare provider, as these substances can interfere with the DEXA scan results.

Additionally, those with severe obesity may not fit into some DEXA machines, and alternative methods may be required.

DEXA scans can be safely performed on children and adolescents when medically necessary. The low radiation dose makes it a suitable option for monitoring bone health in young patients with conditions affecting bone density. However, the cumulative effect of multiple scans should be considered, and the frequency of scans should be minimized. Pediatric patients should only undergo DEXA scans when the benefits clearly outweigh the risks.

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