title: Visualization of boundaries in CT volumetric data sets using dynamic M-|∇f| histogram.
abstract: Direct volume rendering is widely used for three-dimensional medical data visualization such as computed tomography and magnetic resonance imaging. Distinct visualization of boundaries is able to provide valuable and insightful information in many medical applications. However, it is conventionally challenging to detect boundaries reliably due to limitations of the transfer function design. Meanwhile, the interactive strategy is complicated for new users or even experts. In this paper, we build a generalized boundary model contaminated by noise and prove boundary middle value (M) has a good statistical property. Based on the model we propose a user-friendly strategy for the boundary extraction and transfer function design, using M, boundary height (Δh), and gradient magnitude (|∇f|). In fact, it is a dynamic iterative process. First, potential boundaries are sorted orderly from high to low according to the value of their height. Then, users iteratively extract the boundary with the highest value of Δh in a newly defined domain, where different boundaries are transformed to disjoint vertical bars using M-|∇f| histogram. In this case, the chance of misclassification among different boundaries decreases.
authors.affiliation: Electronic Science and Technology, University of Science and Technology of China, Anhui, China. Electronic address: lilu630@mail.ustc.edu.cn.
authors.forename: Lu
authors.initials: L
authors.lastname: Li
authors.affiliation: School of Medical Engineering, Hefei University of Technology, Anhui, China. Electronic address: hpeng@ustc.edu.cn.
authors.forename: Hu
authors.initials: H
authors.lastname: Peng
authors.affiliation: School of Medical Engineering, Hefei University of Technology, Anhui, China. Electronic address: xun.chen@hfut.edu.cn.
authors.forename: Xun
authors.initials: X
authors.lastname: Chen
authors.affiliation: School of Medical Engineering, Hefei University of Technology, Anhui, China. Electronic address: chengjuan@hfut.edu.cn.
authors.forename: Juan
authors.initials: J
authors.lastname: Cheng
authors.affiliation: Department of Mechanical Engineering and Department of Bioengineering University of Washington, Seattle, WA 98195, USA. Electronic address: dayong@u.washington.edu.
authors.forename: Dayong
authors.initials: D
authors.lastname: Gao
mesh_terms: D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: 3-D CT volume; Boundary extraction; Direct volume rendering; Multi-dimensional transfer function; Volume visualization