The British Journal of Radiology, Vol 68, Issue 810 621-629, Copyright © 1995 by British Institute of Radiology

ARTICLES

Comparisons between three dual-energy X-ray absorptiometers used for measuring spine and femur

P Tothill, JA Fenner and DM Reid
Department of Medical Physics, University of Edinburgh, Western General Hospital, UK.

Lunar, Hologic and Norland dual-energy X-ray absorptiometry scanners have been compared for measurements of spine and femur bone density. Precision was not greatly different in realistic phantoms and volunteer subjects. Most clinical therapeutic trials are concerned with measuring changes of bone mineral, and interchangeability in this context was examined using phantoms of spine and femur in which changes of bone mineral density (BMD) were simulated. With each instrument the measured changes were closely linear. For the spine the biggest difference of slope between instruments was 15%. For the femur, in all areas of interest, the differences of slope were less than 10%. It is concluded that the three instruments can be satisfactorily used in multicentre clinical trials to investigate changes in bone mineral. 12 volunteers were measured with each scanner. There were significant mean differences between each pair of instruments, suggesting different calibration criteria. More importantly, those mean differences had appreciable standard deviations (SDs), in proportional terms from 3% to 10%. When the measurements were related to reference ranges and expressed in terms of age-matched normal values the mean biases disappeared, but the SDs did not improve. Results from different manufacturers' apparatus are not interchangeable for studying individual patients. Measurements from the phantoms were used to cross-calibrate the scanners. Those from the variable spine phantom predicted the in vivo ratio within 4%, but this was no better than measurements of the unmodified phantom alone. Results using the European Spine Phantom were less satisfactory. No phantom provided an adequate cross-calibration for femur measurements.

This article has been cited by other articles:

				P Tothill, W J Hannan, and S Wilkinson Comparisons between a pencil beam and two fan beam dual energy X-ray absorptiometers used for measuring total body bone and soft tissue Br. J. Radiol., February 1, 2001; 74(878): 166 - 176. [Abstract] [Full Text] [PDF]

				S. A New, S. P Robins, M. K Campbell, J. C Martin, M. J Garton, C. Bolton-Smith, D. A Grubb, S. J Lee, and D. M Reid Dietary influences on bone mass and bone metabolism: further evidence of a positive link between fruit and vegetable consumption and bone health?1 Am. J. Clinical Nutrition, January 1, 2000; 71(1): 142 - 151. [Abstract] [Full Text] [PDF]