Which statement about DXA is true?

Which statement about DXA is true?

• A. It uses dual-energy X-ray beams to estimate bone mineral density
• B. It measures bone marrow density directly
• C. It does not require calibration
• D. It is not used clinically

Answer: (A)

The main idea is that DXA uses two different X-ray energy levels to separate bone from surrounding soft tissue and estimate bone mineral density. That dual-energy approach is what lets the scanner quantify how much mineral is in the bone, yielding an areal bone mineral density value (in g/cm2). This is why the statement about using dual-energy X-ray beams to estimate bone mineral density is true. It does not measure bone marrow density directly—the technique targets the mineral content in bone itself, not the marrow, so describing it as a marrow measurement would be incorrect. Calibration is required to turn the raw measurements into accurate BMD values and to keep the machine giving trustworthy results, so claiming that calibration isn’t needed is false. And DXA is widely used in clinical practice to assess osteoporosis and fracture risk, which means saying it isn’t used clinically is also false.

The main idea is that DXA uses two different X-ray energy levels to separate bone from surrounding soft tissue and estimate bone mineral density. That dual-energy approach is what lets the scanner quantify how much mineral is in the bone, yielding an areal bone mineral density value (in g/cm2). This is why the statement about using dual-energy X-ray beams to estimate bone mineral density is true. It does not measure bone marrow density directly—the technique targets the mineral content in bone itself, not the marrow, so describing it as a marrow measurement would be incorrect. Calibration is required to turn the raw measurements into accurate BMD values and to keep the machine giving trustworthy results, so claiming that calibration isn’t needed is false. And DXA is widely used in clinical practice to assess osteoporosis and fracture risk, which means saying it isn’t used clinically is also false.