A real-time volumetric visualization system for electrical impedance tomography

Super-sensing technology: industrial applications and future challenges of electrical tomography

Electrical tomography is a relatively new imaging technique that can image the distribution of the passive electrical properties of an object. Since electrical tomography technology was proposed in the 1980s, the technique has evolved rapidly because of its low cost, easy scale-up and non-invasive features. The technique itself can be sensitive to all passive electrical properties, such as conductivity, permittivity and permeability. Hence, it has a huge potential to be applied in many applications. Owing to its ill-posed nature and low image resolution, electrical tomography attracts more attention in industrial fields than biomedical fields. In the past decades, there have been many research developments and industrial implementations of electrical tomography; nevertheless, the awareness of this technology in industrial sectors is still one of the biggest limitations for technology implementation. In this paper, the authors have summarized several representative applications that use electrical tomography. Some of the current tomography research activities will also be discussed. This article is part of the themed issue 'Supersensing through industrial process tomography'.

Visualization of multidimensional and multimodal tomographic medical imaging data, a case study

Multidimensional tomographic datasets contain physical properties defined over four-dimensional (e.g. spatial-temporal, spatial-spectral), five-dimensional (e.g. spatial-temporal-spectral) or even higher-dimensional domains. Multimodal tomographic datasets contain physical properties obtained with different imaging modalities. In medicine, four-dimensional data are widely used, five-dimensional data are emerging, and multimodal data are being used more often every day. Visualization is vital for medical diagnosis and surgical planning to interpret the information included in imaging data. Visualization of multidimensional and multimodal tomographic imaging data is still a challenging task. As a case study, our work focuses on the visualization of five-dimensional (spatial-temporal-spectral) brain electrical impedance tomography (EIT) data. In this paper, a task-based subset definition scheme is proposed: a task model named Cubic Task Explorer (CTE) is derived to support the visualization task exploration for medical imaging data, and a structured method for visualization system development called Task-based Multi-Dimensional Visualization (TMDV) is proposed. A prototype system named EIT5DVis is developed using the CTE model and TMDV method to visualize five-dimensional brain EIT data.

Real-time stereographic rendering and display of medical images with programmable GPUs

The study was to explore the power and feasibility of using programmable graphics processing units (GPUs) for real-time rendering and displaying large 3D medical datasets for stereoscopic display workstation. Lung cancer screening CT images were used for developing GPU-based stereo rendering and displaying. The study was run on a personal computer with a 128 MB NVIDIA Quadro FX 1100 graphics card. The performance of rendering and displaying was measured and compared between GPU-based and central processing unit (CPU)-based programming. The results indicate that GPU-based programming was capable of rendering large 3D datasets at real-time interactive rates with stereographic displays.

Phasic three-dimensional impedance imaging of cardiac activity

Electrical impedance images were made using the ACT 3 instrument, which applies currents simultaneously to 32 electrodes and measures the resulting voltages on those same electrodes. A reconstruction algorithm was written for a three-dimensional cylinder having electrodes in two or four layers, using current patterns that pass current among different planes of electrodes, as well as within each plane. We have previously reported useful vertical resolution by the use of added layers of electrodes. The aim of the present study was to demonstrate that physiologically useful information can be obtained by examining cephalo-caudal differences in three-dimensional images. Phasic changes throughout the cardiac cycle are seen to be markedly different at the heart compared to lung region, both above and beside it. We formed hydrogel electrodes each 3 cm tall and 7 cm wide and applied them to the thorax of an upright human subject in four horizontal rows; each row contained eight electrodes. During breath-holding, cardiac activity was seen in all layers. With systole, conductivity in the anterior of the lowest layers decreased, but not in the upper layer. In the upper layers, conductivity increased with systole in many regions. These observations are consistent with the opposite changes in blood volume of the heart and lungs and the locations of these organs. This paper demonstrates the feasibility of producing and displaying physiologically interpretable three-dimensional images of the chest in real time.