Comparative assessment of dual-photon absorptiometry and dual-energy radiography

Radiology. 1990 Jan;174(1):223-8. doi: 10.1148/radiology.174.1.2294552.


Dual-energy bone densitometry can be performed with two types of scanners. The traditional dual-photon absorptiometry (DPA) machines use an isotope source, whereas the newly introduced dual-energy radiography (DER) devices use an incorporated x-ray tube. The authors evaluated the performance of DPA and DER devices at their institution. The short-term precision error in vivo was 1.2% for femoral neck measurements with DER. Long-term precision error in vitro was reduced from 1.30% (DPA) to 0.44% (DER). The scanning time for both spine and hip measurements was reduced from 20-40 minutes to 6-7 minutes. Intraosseous fat sensitivity remained the same, at a level of 12 mg/cm2 apparent decrease of bone mineral density (BMD) per 10% fat by volume change, and for both devices there was no shift in BMD when phantom thickness was increased by 1.5 inches. The correlation of DPA and DER was high: r = .98 for the spine and r = .95 for the femoral neck. Correlation of DPA versus quantitative computed tomography (CT) (r = .83) and DER versus quantitative CT (r = .85) was good. The advent of DER represents a significant advance for the field of bone densitometry.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Absorptiometry, Photon*
  • Adult
  • Bone Density*
  • Densitometry / methods
  • Femur Neck
  • Humans
  • Lumbar Vertebrae
  • Models, Structural
  • Radiography, Dual-Energy Scanned Projection*