Hybrid cone-beam tomographic reconstruction: incorporation of prior anatomical models to compensate for missing data.
We propose a method for improving the quality of cone-beam tomographic reconstruction done with a C-arm. C-arm scans frequently suffer from incomplete information due to image truncation, limited scan length, or other limitations. Our proposed "hybrid reconstruction" method injects information from a prior anatomical model, derived from a subject-specific computed tomography (CT) or from a statistical database (atlas), where the C-arm X-ray data is missing. This significantly reduces reconstruction artifacts with little loss of true information from the X-ray projections. The methods consist of constructing anatomical models, fast rendering of digitally reconstructed radiograph (DRR) projections of the models, rigid or deformable registration of the model and the X-ray images, and fusion of the DRR and X-ray projections, all prior to a conventional filtered back-projection algorithm. Our experiments, conducted with a mobile image intensifier C-arm, demonstrate visually and quantitatively the contribution of data fusion to image quality, which we assess through comparison to a "ground truth" CT. Importantly, we show that a significantly improved reconstruction can be obtained from a C-arm scan as short as 90° by complementing the observed projections with DRRs of two prior models, namely an atlas and a preoperative same-patient CT. The hybrid reconstruction principles are applicable to other types of C-arms as well.
Sadowsky
Ofri
O
Department of Computer Science, The Johns Hopkins University, Baltimore, MD 21218, USA.
Lee
Junghoon
J
Sutter
E Grant
EG
Wall
Simon J
SJ
Prince
Jerry L
JL
Taylor
Russell H
RH
D000465:Algorithms; D000818:Animals; D016477:Artifacts; D002678:Chimera; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008953:Models, Anatomic; D015233:Models, Statistical; D019047:Phantoms, Imaging; D011856:Radiographic Image Enhancement; D014057:Tomography, X-Ray Computed / Q000379:methods*