Accessing 3D Location of Standing Pelvis: Relative Position of Sacral Plateau and Acetabular Cavities versus Pelvis

<table>Illustrating the method for locating frames affixed to acetabular cavities from biplanar radiography coupled with geometric modelling. Each acetabular cavity is modelled as an hemisphere bounded by a circular brim. The modelled circular brim of center <svg height="15.6875" id="M61" style="vertical-align:-3.39066pt" version="1.1" viewbox="0 0 19.825001 15.6875" width="19.825001" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
<g transform="matrix(.017,-0,0,-.017,.062,11.4)"><use xlink:href="#x1D442"></use></g>
<g transform="matrix(.012,-0,0,-.012,13.113,15.475)"><use xlink:href="#x1D44E"></use></g>
</svg> and axis <svg height="11.9625" id="M62" style="vertical-align:-3.39066pt" version="1.1" viewbox="0 0 15.3 11.9625" width="15.3" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
<g transform="matrix(.017,-0,0,-.017,.062,7.675)"><use xlink:href="#x1D45B"></use></g>
<g transform="matrix(.012,-0,0,-.012,8.6,11.762)"><use xlink:href="#x1D44E"></use></g>
</svg> is projected in frontal and sagittal X-rays. Elliptic projections of circular brim must coincide with the real brim contours. These last ones are determined from landmarks recorded along the contour projections. Real brim images and 3D modelled brim projections are then best fitted.</table>

Radiology Research and Practice

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Figure 3

Figure 3: Accessing 3D Location of Standing Pelvis: Relative Position of Sacral Plateau and Acetabular Cavities versus Pelvis 