What it is
DXA estimates bone mineral density using low-dose X-rays. Reports usually include BMD plus T-score or Z-score where appropriate.[1,2]
Why it matters
It is a common way to document bone density and fracture-risk context, but it is not the whole definition of bone strength.[1]
Root causes of abnormal values
- Measurement core: DXA changes when the low-dose X-ray measurement pipeline estimates less or more mineral signal in the scanned bone area. The core chain is dual-energy X-ray attenuation -> separation of soft-tissue and bone signal -> areal BMD estimate -> T-score or Z-score where appropriate.[1,2]
- Technical context: The number can be shifted by skeletal site, positioning, scanner and reference database, body size, vertebral change, fracture, hardware, calcification, or other artifacts. A DXA result is therefore a measured estimate in a specific context, not a direct measurement of whole-bone strength.[3,2]
- Reading boundary: BioConst can explain why DXA belongs in a bone-density and fracture-context map, but it does not decide who should be screened, diagnose osteoporosis, compare unrelated scanners, or recommend treatment.[1,3]
What it affects
Interpretation traps
- Machine, site, positioning, artifacts, degenerative change, and body size can affect interpretation.[3]