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Proceedings Paper

Precision and accuracy of 3D lower extremity residua measurement systems
Author(s): Paul K. Commean; Kirk E. Smith; Michael W. Vannier M.D.; Charles F. Hildebolt D.D.S.; Thomas K. Pilgram
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Paper Abstract

Accurate and reproducible geometric measurement of lower extremity residua is required for custom prosthetic socket design. We compared spiral x-ray computed tomography (SXCT) and 3D optical surface scanning (OSS) with caliper measurements and evaluated the precision and accuracy of each system. Spiral volumetric CT scanned surface and subsurface information was used to make external and internal measurements, and finite element models (FEMs). SXCT and OSS were used to measure lower limb residuum geometry of 13 below knee (BK) adult amputees. Six markers were placed on each subject's BK residuum and corresponding plaster casts and distance measurements were taken to determine precision and accuracy for each system. Solid models were created from spiral CT scan data sets with the prosthesis in situ under different loads using p-version finite element analysis (FEA). Tissue properties of the residuum were estimated iteratively and compared with values taken from the biomechanics literature. The OSS and SXCT measurements were precise within 1% in vivo and 0.5% on plaster casts, and accuracy was within 3.5% in vivo and 1% on plaster casts compared with caliper measures. Three-dimensional optical surface and SXCT imaging systems are feasible for capturing the comprehensive 3D surface geometry of BK residua, and provide distance measurements statistically equivalent to calipers. In addition, SXCT can readily distinguish internal soft tissue and bony structure of the residuum. FEM can be applied to determine tissue material properties interactively using inverse methods.

Paper Details

Date Published: 16 April 1996
PDF: 17 pages
Proc. SPIE 2710, Medical Imaging 1996: Image Processing, (16 April 1996); doi: 10.1117/12.237953
Show Author Affiliations
Paul K. Commean, Mallinckrodt Institute of Radiology/Washington Univ. School of Medicine (United States)
Kirk E. Smith, Mallinckrodt Institute of Radiology/Washington Univ. School of Medicine (United States)
Michael W. Vannier M.D., Mallinckrodt Institute of Radiology/Washington Univ. School of Medicine (United States)
Charles F. Hildebolt D.D.S., Mallinckrodt Institute of Radiology/Washington Univ. School of Medicine (United States)
Thomas K. Pilgram, Mallinckrodt Institute of Radiology/Washington Univ. School of Medicine (United States)


Published in SPIE Proceedings Vol. 2710:
Medical Imaging 1996: Image Processing
Murray H. Loew; Kenneth M. Hanson, Editor(s)

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