Title — Divergent-beam backprojection-filtration formula with applications to region-of-interest imaging
Abstract — Interventional neuroradiology treats vascular pathologies of the brain through minimally invasive, endovascular procedures. These treatments are performed under the control of two-dimensional, real-time, projective X-ray imaging using interventional C-arm systems. Such systems can perform tomographic acquisitions (which are further used to reconstruct a three-dimensional image) by rotating the C-arm around the patient; however, C-arm cone-beam computed tomography (CBCT) achieves a lower contrast resolution (which is necessary to recover the clinical information of soft tissues in the brain) than diagnostic CT, mostly because of dose (thus noise) issues. Interestingly, C-arm CBCT is often used for region-of-interest (ROI) imaging, again with limited contrast detection due to truncation artifacts. In this talk, we revisit the classical direct filtered backprojection (FBP) reconstruction algorithm and propose a new alternative, backprojection-filtration (BPF) formula, that is exact in planar geometries and approximate in the cone-beam geometry. We then apply this result to the reconstruction of dual-rotation acquisitions, consisting of a truncated low-noise acquisition with dense angular sampling, and of additional non-truncated views that are either high-noise or angularly undersampled. In both cases, the method successfully improves contrast resolution on digital phantoms and on real dual-rotation acquisitions of a quality assurance phantom (Catphan 515).
Biography — Aymeric Reshef received his MSc in Mathematics, Vision and Learning from ENS Cachan in 2014. He joined GE Healthcare (Buc, France) in 2014 for a PhD (CIFRE industrial research agreement) in collaboration with Télécom ParisTech’s Laboratory for communication and processing of information (LTCI, Paris, France), supervised by Isabelle Bloch. Since 2018, he is an Image Quality Engineer in the Interventional Guidance Solutions team at GE Healthcare (Buc, France). His research interests include image processing, medical physics, tomographic reconstruction and inverse problems.