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Advances in Biomechanics & Applications
  Volume 1, Number 1, March 2014, pages 015-22
DOI: http://dx.doi.org/10.12989/aba.2013.1.1.015
 
open access

Repeatable calibration of Hounsfield units to mineral density and effect of scanning medium
Meghan Crookshank, Heidi-Lynn Ploeg, Randy Ellis and Norma J. MacIntyre

 
Abstract
    Computed tomography (CT) is being utilized in orthopaedics and related research to estimate bone strength. These applications benefit from calibration of Hounsfield units to mineral density typical of long bone, up to 1750mg/cm3. This study describes a method for establishing repeatable calibration of Hounsfield units to density, and determines the effects of imaging medium on calibration accuracy. Four hydroxyapatite standards were imaged in air on 7 occasions over 19 weeks using a helical multi-slice CT scanner. Each standard was scanned 5 times in different media: porcine soft tissue, water, and air. Calibrated densities were highly repeatable (CV<3.5%). No difference in density was observed between water and soft tissue conditions (p>0.08). This work provides a model for determining repeatable scanner-specific density calibration, demonstrates that the linear relationship between Hounsfield units and density extends to values typical of cortical bone, and supports the practice of imaging calibration standards in an environment similar to that of the target bone.
 
Key Words
    computed tomography; reliability; cortical bone; trabecular bone; bone density
 
Address
Meghan Crookshank: Biomedical Engineering, University of Toronto, Toronto, ON M5B 1W8, Canada; Human Mobility Research Centre, Queen' s University & Kingston General Hospital, Kingston, ON K7L 3N6, Canada
Heidi-Lynn Ploeg: Human Mobility Research Centre, Queen' s University & Kingston General Hospital, Kingston, ON K7L 3N6, Canada; Mechanical Engineering, University of Wisconsin, Madison, WI 53706, USA
Randy Ellis: Human Mobility Research Centre, Queen' s University & Kingston General Hospital, Kingston, ON K7L 3N6, Canada;School of Computing, Queen' s University, Kingston, ON K7L 3N6, Canada
Norma J. MacIntyre: Human Mobility Research Centre, Queen' s University & Kingston General Hospital, Kingston, ON K7L 3N6, Canada;School of Rehabilitation Science, McMaster University, Hamilton, ON L8S 1C7, Canada
 

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