Summary of Available Bone Mass Measurement Technologies

SUMMARY OF BONE MINERAL DENSITY MEASUREMENTS

DXA: spine, hip, total body

pDXA: forearm, finger, heel

SXA: heel

QUS: heel, shin

QCT: spine

pQCT: forearm

Figure 1.

DXA: Dual-Energy X-Ray Absorptiometry

Most widely used and has been the most thoroughly studied BMD measurement technology.
Uses two x-ray beams: one at higher energy and one at lower energy. After subtraction of the soft-tissue absorption, the absorption of each beam by bone is used in calculation the BMD value.
Measures BMD at central or peripheral body sites.

pDXA: DXA at peripheral sites

SXA: Single-Energy X-Ray Absorptiometry

Uses a single energy x-ray beam for measurement and a water bath to simulate a uniform soft-tissue thickness.
Properties: small size, portable

QCT: Quantitative Computed Tomography

pQCT: Peripheral QCT

Summary of Available Bone Mass Measurement Technologies
METHOD	BODY SITE	ACCURACY	Effective Radiation Dose
DXA Dual-Energy X-Ray Absorptiometry	Hip Spine Total Body	90-99%	<<0.1 mSv*
pDXA Peripheral Dual-Energy X-Ray Absorptiometry	Forearm Finger Heel	90-99%	<<0.1 mSv*
SXA Single-Energy X-ray Absorptiometry	Heel	98-99%	<<0.1 mSv*
QUS Quantitative Ultrasound	Heel Shin	N/A	None
QCT Quantitative Computed Tomography	Spine	85-97%	≤0.1 mSv*
pQCT Peripheral Quantitative Computed Tomography	Forearm	92-98%	<<0.1 mSv*
*For comparison; a chest x-ray has an effective dose equivalent of 0.1 mSv << = Significantly less than