title: Comparing performance of many-core CPUs and GPUs for static and motion compensated reconstruction of C-arm CT data.
abstract: OBJECTIVE
  Interventional reconstruction of 3-D volumetric data from C-arm CT projections is a computationally demanding task. Hardware optimization is not an option but mandatory for interventional image processing and, in particular, for image reconstruction due to the high demands on performance. Several groups have published fast analytical 3-D reconstruction on highly parallel hardware such as GPUs to mitigate this issue. The authors show that the performance of modern CPU-based systems is in the same order as current GPUs for static 3-D reconstruction and outperforms them for a recent motion compensated (3-D+time) image reconstruction algorithm.
  
  
  METHODS
  This work investigates two algorithms: Static 3-D reconstruction as well as a recent motion compensated algorithm. The evaluation was performed using a standardized reconstruction benchmark, RABBITCT, to get comparable results and two additional clinical data sets.
  
  
  RESULTS
  The authors demonstrate for a parametric B-spline motion estimation scheme that the derivative computation, which requires many write operations to memory, performs poorly on the GPU and can highly benefit from modern CPU architectures with large caches. Moreover, on a 32-core Intel Xeon server system, the authors achieve linear scaling with the number of cores used and reconstruction times almost in the same range as current GPUs.
  
  
  CONCLUSIONS
  Algorithmic innovations in the field of motion compensated image reconstruction may lead to a shift back to CPUs in the future. For analytical 3-D reconstruction, the authors show that the gap between GPUs and CPUs became smaller. It can be performed in less than 20 s (on-the-fly) using a 32-core server.
authors.affiliation: Pattern Recognition Laboratory, Universität Erlangen-Nürnberg, 91058 Erlangen, Germany. hannes.hofmann@cs.fau.de
authors.forename: Hannes G
authors.initials: HG
authors.lastname: Hofmann
authors.forename: Benjamin
authors.initials: B
authors.lastname: Keck
authors.forename: Christopher
authors.initials: C
authors.lastname: Rohkohl
authors.forename: Joachim
authors.initials: J
authors.lastname: Hornegger
mesh_terms: D000465:Algorithms; D003196:Computer Graphics; D003201:Computers; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D009068:Movement; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*