title: Wobbled splatting--a fast perspective volume rendering method for simulation of x-ray images from CT.
abstract: 3D/2D registration, the automatic assignment of a global rigid-body transformation matching the coordinate systems of patient and preoperative volume scan using projection images, is an important topic in image-guided therapy and radiation oncology. A crucial part of most 3D/2D registration algorithms is the fast computation of digitally rendered radiographs (DRRs) to be compared iteratively to radiographs or portal images. Since registration is an iterative process, fast generation of DRRs-which are perspective summed voxel renderings-is desired. In this note, we present a simple and rapid method for generation of DRRs based on splat rendering. As opposed to conventional splatting, antialiasing of the resulting images is not achieved by means of computing a discrete point spread function (a so-called footprint), but by stochastic distortion of either the voxel positions in the volume scan or by the simulation of a focal spot of the x-ray tube with non-zero diameter. Our method generates slightly blurred DRRs suitable for registration purposes at framerates of approximately 10 Hz when rendering volume images with a size of 30 MB.
authors.affiliation: Center for Biomedical Engineering and Physics, Medical University Vienna, Vienna, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Birkfellner
authors.forename: Rudolf
authors.initials: R
authors.lastname: Seemann
authors.forename: Michael
authors.initials: M
authors.lastname: Figl
authors.forename: Johann
authors.initials: J
authors.lastname: Hummel
authors.forename: Christopher
authors.initials: C
authors.lastname: Ede
authors.forename: Peter
authors.initials: P
authors.lastname: Homolka
authors.forename: Xinhui
authors.initials: X
authors.lastname: Yang
authors.forename: Peter
authors.initials: P
authors.lastname: Niederer
authors.forename: Helmar
authors.initials: H
authors.lastname: Bergmann
mesh_terms: D000465:Algorithms; D021621:Imaging, Three-Dimensional / Q000379:methods*; D016247:Information Storage and Retrieval / Q000379:methods; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D013382:Subtraction Technique; D014057:Tomography, X-Ray Computed / Q000379:methods*