DEXA Bone Density Scan

Dual-energy X-ray absorptiometry (DEXA) scan measuring bone mineral density at key skeletal sites. This low-radiation imaging test is the standard method for diagnosing osteoporosis and assessing fracture risk, producing a T-score that compares your bone density against a healthy young adult reference population.

The DEXA scan at Tokyo Midtown Clinic uses dual-energy X-ray absorptiometry to measure bone mineral density with high precision and minimal radiation exposure — typically less than one-tenth the dose of a standard chest X-ray. The scan focuses on the lumbar spine and proximal femur (hip), the two sites most predictive of osteoporotic fracture risk, though additional sites such as the forearm can be measured if clinically indicated. The technology works by passing two X-ray beams of different energy levels through the bone. The difference in absorption between the two beams allows the system to calculate bone mineral content and areal density, expressed as grams per square centimetre. Results are reported as a T-score (comparison to peak bone mass in a healthy 30-year-old) and a Z-score (comparison to age-matched peers). A T-score of minus 1.0 or above is considered normal, between minus 1.0 and minus 2.5 indicates osteopenia (low bone mass), and below minus 2.5 qualifies as osteoporosis according to World Health Organization criteria. The scan itself takes approximately 10 to 15 minutes. The patient lies on a padded table while the scanner arm passes over the measurement sites. There is no enclosed tunnel and no noise — the experience is far less claustrophobic and faster than an MRI. No special preparation is required beyond removing metal objects from the scan area. DEXA is particularly valuable as a longitudinal tracking tool. When repeated at the same facility using the same machine, it can detect changes in bone density as small as one to two percent per year, making it useful for monitoring the effectiveness of exercise programmes, dietary changes, or pharmaceutical interventions aimed at preserving or building bone mass. At Tokyo Midtown Clinic, the results are integrated into the patient's overall health report if booked alongside a dock package, with the physician incorporating bone health findings into the broader assessment. For standalone bookings, a brief consultation is included to explain the T-score and discuss any follow-up recommendations.