DEXA (Dual‑Energy X‑ray Absorptiometry) is the gold‑standard imaging technique for measuring bone mineral density (BMD). It is the primary diagnostic tool for osteoporosis, fracture‑risk assessment, and monitoring bone health over time. DEXA uses two low‑energy X‑ray beams to differentiate bone from soft tissue with exceptional precision.
Modern DEXA systems provide rapid, low‑dose imaging of the lumbar spine, hip, and forearm, along with advanced tools such as vertebral fracture assessment (VFA), body composition analysis, and trabecular bone score (TBS).
DEXA measures bone mineral density by comparing the absorption of two X‑ray energies as they pass through bone and soft tissue. This allows precise quantification of bone mass and identification of osteoporosis before fractures occur. DEXA is fast, painless, and exposes patients to extremely low radiation.
Standard scan sites include the lumbar spine and proximal femur, which are most predictive of fracture risk. Forearm scans are used when hip or spine imaging is not possible. DEXA also provides Z‑scores and T‑scores, which classify bone health according to WHO criteria.
Advanced DEXA systems offer body composition analysis, including fat mass, lean mass, and visceral fat estimation, making DEXA valuable in metabolic and sports medicine.
Source: International Society for Clinical Densitometry
DEXA is essential for diagnosing osteoporosis, monitoring treatment response, and assessing fracture risk. It is recommended for postmenopausal women, men over 70, individuals with risk factors such as long‑term steroid use, and patients with fragility fractures.
DEXA provides highly reproducible measurements, allowing clinicians to track bone density changes over time. Vertebral fracture assessment (VFA) can detect silent compression fractures, which significantly increase future fracture risk.
DEXA is also used in pediatrics, bariatrics, endocrinology, and sports medicine to evaluate growth disorders, nutritional status, and muscle‑to‑fat ratios.
Source: National Osteoporosis Foundation
Spine & Hip BMD
Forearm BMD
Whole‑body Composition
Extremely low dose
Lower than chest X‑ray
Safe for routine monitoring
Osteoporosis diagnosis
Fracture‑risk assessment
Therapy monitoring
Source: ISCD
DEXA facilities follow standards set by the International Society for Clinical Densitometry (ISCD) and the American College of Radiology (ACR). Accreditation ensures proper calibration, technologist competency, and consistent scan quality.
Quality control includes daily phantom scans, precision assessments, and strict positioning protocols to ensure reproducible results.
Source: ISCD
Is DEXA safe? Yes. DEXA uses extremely low radiation—far less than standard X‑rays.
How long does a scan take? Most exams take 5–10 minutes.
Who should get a DEXA scan? Adults over 65, postmenopausal women, and individuals with risk factors for bone loss.
Source: National Osteoporosis Foundation
DEXA technologists require training in anatomy, densitometry physics, patient positioning, precision assessment, and quality control. Certification is available through ISCD and ARRT post‑primary pathways.
Students learn to interpret T‑scores, Z‑scores, and understand WHO diagnostic criteria for osteoporosis and osteopenia.
Source: ISCD