Measurement Tools — DEXA
What It Is
DEXA
Dual energy X-ray absorptiometry (DEXA) is based on dividing the body into three compartments: total body mineral (from bones), fat-free soft (lean) mass, and fat tissue mass.
- The person is scanned with photons that are generated by two low-dose x-rays at different energy levels.
- The body's absorption of the photons at the two levels is measured.
- The ratios arecan be then used to predict total body fat, fat-free mass, and total body bone mineral.
Equipment Used
A whole body scanner with the x-ray sources mounted beneath a table and a detector overhead.
How It's Done
- Person lies on a table and is scanned.
- Measurements take about 10 - 20 minutes.
Pros
- It's considered a reference standard, and the latest body composition research uses this method.
- It's precise, accurate, and reliable.
- It's safe.
- It's noninvasive.
- It can be used to determine body fat distribution.
Cons
- The narrow table limits its use with heavier people.
- The equipment is expensive.
- It's used primarily in laboratory settings.
Illustration courtesy Tanita Corporation of America Inc.
