A method to obtain 3D structural measurements of the proximal femur from 2D DXA images and a statistical atlas is
presented. A statistical atlas of a proximal femur was created consisting of both 3D shape and volumetric density
information and then deformably registered to 2D fan-beam DXA images. After the registration process, a series of 3D
structural measurements were taken on QCT-estimates generated by transforming the registered statistical atlas into a
voxel volume. These measurements were compared to the equivalent measurements taken on the actual QCT (ground
truth) associated with the DXA images for each of 20 human cadaveric femora. The methodology and results are
presented to address the potential clinical feasibility of obtaining 3D structural measurements from limited angle DXA
scans and a statistical atlas of the proximal femur in-vivo.
In this paper we present a source path for the purpose of exact cone-beam reconstruction using a C-arm X-ray imaging system. The proposed path consists of two intersecting segments, each of which is a short-scan. Any C-arm capable of a short-scan sweep can thus be used to obtain data on our proposed source path as well, since it only requires an additional sweep on a tilted plane. This tilt can be achieved by either using the propeller axis of mobile C-arms, or the vertical axis of ceiling mounted C-arms. While the individual segments are only capable of exact reconstruction in their mid-plane, we show that the combined path is capable of exact reconstruction within an entire volumetric region. In fact, we show that the
largest sphere that can be captured in the field of view of the C-arm can be exactly reconstructed if the tilt between the planes is at least equal to the cone-angle of the system. For the purpose of
cone-beam inversion we use a generalized cone-beam filtered backprojection algorithm (CB-FBP).
The exactness of this method relies on the design of a set of redundancy weights, which we
explicitly evaluate for the proposed dual short-scan source path.