Gert Behiels

Modeling blurring effects due to continuous gantry rotation: Application to region of interest tomography.

PURPOSE Projections acquired with continuous gantry rotation may suffer from blurring effects, depending on the rotation speed and the exposure time of each projection. This leads to blurred reconstructions if conventional reconstruction algorithms are applied. In this paper, the authors propose a reconstruction method for fast acquisitions based on a continuously moving and continuously emitting x-ray source. They study the trade-off between total acquisition time and reconstruction quality and compare with conventional reconstructions using projections acquired with a stepwise moving x-ray source. METHODS The authors introduce the algebraic reconstruction technique with angular integration concept, which models the angular integration due to the relative motion of the x-ray source during the projection. RESULTS Compared to conventional reconstruction from projections acquired with pulsed x-ray emission, the proposed method results in substantially improved reconstruction quality around the center of rotation. Outside this region, the proposed method results in improved radial resolution and a decreased tangential resolution. For a fixed reconstruction quality of this region of interest, the proposed method enables a lower number of projections and thus a faster acquisition. CONCLUSIONS The modeling of the continuous gantry rotation in the proposed method substantially improves the reconstruction quality in a region of interest around the rotation center. The proposed method shows potential for fast region of interest tomography.

Mass candidate detection and segmentation in digitized mammograms

This paper introduces a system for identifying candidate masses in digitized mammograms. Mass identification is a basic component in Computer-Aided Detection (CAD) systems for mammograms. The proposed algorithm is a cascaded filtering process that consists of several stages: First, a new breast fat model is introduced and the fat content in the image is estimated and removed from the image to obtain a fatless image at a standard resolution. Next, a Gabor filter is specially designed and tailored to fit the mass detection problem and then applied to the fatless image. Finally, the resulting image is segmented to obtain iso-contours. Candidate regions are then identified by contour processing and selection. The proposed algorithm obtained 100% sensitivity with 3.4 false positives per image

Can portable tomosynthesis improve the diagnostic value of bedside chest X-ray in the intensive care unit? A proof of concept study

Portable bedside chest X-ray (CXR) is an important and frequently used tool in the intensive care unit (ICU). Unfortunately, the diagnostic value of portable CXR is often low due to technical limitations and suboptimal patient positioning. Additionally, abnormalities in the chest may be hidden on the projection image by overlapping anatomy and devices such as endotracheal tubes, lines and catheters. Digital tomosynthesis (DTS) can solve the problem of anatomical overlap. In DTS, several low-dose X-ray images from different angles are acquired and subsequently used by a reconstruction algorithm to compute section images along planes parallel to the detector. However, a portable device to be used for portable bedside chest DTS is not on the market yet. In this work, we discuss modifications to a portable X-ray device to enable portable DTS and illustrate the potential of portable DTS to improve the diagnostic value of bedside CXR in the ICU. A simulation, based on computed tomography scans, is presented. Our experiments comparing portable DTS with conventional bedside CXR showed a substantially improved detection of pneumothorax and other abnormalities.

Intelligent Synchronized Magnifying Glasses for Assisting Reading of Temporal Mammograms

This paper describes a framework which aims at assisting the clinical analysis of temporal mammograms. The framework exists of a processing part and a visualization part. The core components of the processing part are (1) an algorithm for spatial registration of two successive mammograms, (2) a method for automatic detection of Micro-Calcifications (MCs) and Micro-Calcification Clusters (MCCs) and, (3) an algorithm that allows an automatic identification of detected MCs and MCCs between two successive images. For the presentation of registration, detection and identification results, we present a visualization tool, called “Intelligent Synchronized Magnifying Glasses” (ISMAG), which allows a visualization of the results in an intuitive and non distracting way.