DEXA Radiation Exposure
The radiation dose from a DEXA scan is negligible—less than one chest X-ray or a short airplane flight—and poses essentially no meaningful health risk to patients. 1
Quantified Radiation Exposure Levels
The actual radiation exposure from DEXA scanning is extremely low across all measurement sites:
- Standard DEXA (spine and hip): Approximately 2.5 microsieverts (µSv) effective dose 2
- Whole body DEXA with vertebral fracture assessment: A few microsieverts at most 3
- Total effective dose for spine and dual femur examination: Comparable to a few microsieverts 3
For context, these doses are substantially lower than other common imaging modalities:
- A single abdominal X-ray delivers approximately 100 µSv (40 times higher than DEXA) 2
- Quantitative CT (QCT) for bone density delivers 300-1000 µSv (120-400 times higher than DEXA) 2
Relative Radiation Level Classification
The American College of Radiology assigns DEXA the lowest possible relative radiation level (RRL) designation, indicated by a single radiation symbol (☢), confirming its minimal exposure profile. 1 This classification places DEXA at the absolute bottom of the diagnostic radiology exposure spectrum. 2
Clinical Risk Assessment
The radiation risk from DEXA is so low that it should never be a factor in clinical decision-making about whether to perform the scan. 2 The effective dose is considered negligible even in vulnerable populations including:
- Pediatric patients: Despite children being inherently more radiosensitive due to organ sensitivity and longer life expectancy, DEXA remains appropriate when clinically indicated 1
- Cancer survivors: Even in childhood, adolescent, and young adult cancer survivors who have already received therapeutic radiation, the dose from one DEXA scan is considered negligible 1
- Patients requiring serial monitoring: Repeat DEXA scans every 1-2 years for monitoring are appropriate without meaningful cumulative radiation concern 4, 5
Important Caveats
While radiation exposure from DEXA is minimal, clinicians should still adhere to basic radiation safety principles:
- Clinical justification: Each examination must be clinically justified, as with any X-ray imaging technique 6
- ALARA principle: Keep doses as low as reasonably achievable while ensuring diagnostic quality 1
- Avoid unnecessary anxiety: Predictions of cancer deaths from low-dose medical imaging (including DEXA) are not supported by hard data and create harmful patient anxiety that may lead to refusal of needed procedures 1
The adverse health consequences of refusing a needed DEXA scan far outweigh any theoretical radiation-associated risks. 1
Comparison to Alternative Modalities
When bone density assessment is needed, DEXA should be strongly preferred over CT-based methods from a radiation perspective:
- QCT delivers 120-400 times more radiation than DEXA 2
- High-resolution MDCT for bone structure evaluation: 1-3 millisieverts (mSv), which is 400-1200 times higher than DEXA 6
The American College of Radiology rates standard DEXA of the lumbar spine and hips as the most appropriate modality (rating 9/9) for bone mineral density screening, with its minimal radiation exposure being one contributing factor. 1, 4