DXA Bone Density Screening
Dual-energy X-ray absorptiometry of lumbar spine + proximal femur (and sometimes forearm) — standard screening for osteoporosis in postmenopausal women, men over 70, and patients on chronic steroids or with secondary risk factors. Extremely low radiation dose (~1 µSv per site). Results reported as T-score and Z-score referenced to manufacturer's normative database; FRAX 10-year fracture risk computed from BMD + clinical risk factors.
Clinical pathway
- Patient positioning — supine on table, feet in positioner for hip scan.
- Lumbar spine AP scan — L1–L4, exclude fractured or osteophytic vertebrae from analysis.
- Proximal femur scan — femoral neck, total hip.
- Optional VFA (vertebral fracture assessment) — lateral T4–L4 to detect morphometric fractures.
- Reporting — lowest T-score determines diagnosis; ISCD guidelines for serial comparison.
Typical systems
- Hologic Horizon A
- GE Lunar iDXA / Prodigy family
Hologic and GE Lunar normative databases are NOT cross-comparable — serial scans must be on the same manufacturer's system (and ideally the same unit) for meaningful comparison.
Room + procedure characteristics
- Scan time: 5–10 min total including positioning
- Dose: <10 µSv per scan (less than a day of natural background)
- Team: DXA-trained tech, interpretation by radiologist or endocrinologist