Current Issue
Volume 4 Issue 1
Research Article
Rui Liu, Mannudeep K. Kalra, and Hengyong Yu*
The obese population is increasing in the United States. There have been modest improvements in scanner hardware and image processing to address some specific challenges associated with imaging of the morbidly obese patients. However, most legacy CT systems lack capabilities to provide sufficient delivery of image-based diagnosis in this increasing subset of population. One of the most common problems is the projection data truncation in CT imaging due to the massive girths of obese patients. In the past decade, it was proved that the image can be accurately and stably reconstructed from locally truncated projections if certain prior knowledge is known, and this technique is named interior tomography. To overcome the time-consuming issue of the iterative algorithms, we apply GPU techniques to speed up the reconstruction process. In this paper, we evaluate the GPU-based CT reconstruction algorithms (one analytic algorithm and one iterative reconstruction algorithm) for obese patients with both simulated and real clinical datasets. While the approximate analytic reconstruction algorithm outperforms the iterative reconstruction (IR) algorithm in terms of computational cost, the IR algorithm outperforms the analytic one in terms of image quality especially when the projection data is suffered from patient motion, which can happen when the obese patients are not able to hold a breath during the scan.
Matthew Getzin, Rachel Berry, Andrea O'Brisky, Guang Li, Jian Kang, Rick Relyea, Mark E. Pennesi, and Ge Wang*
Electroretinography (ERG) is an established approach to measure the retinal response to light. Under different lighting conditions, this method can determine rod and/or cone sensitivity to different wavelengths and intensities of light stimuli. ERGs are often performed with visible light flashes, although some experiments were done with UV light and even X-rays. Bachofer and Wittry reported in the 1960s that when the eyes of Northern leopard frogs (Rana pipiens) were irradiated with X-rays, their ERG responses were significant. As reported in their early papers, retinal electrophysiological signals elicited by visible light and X-ray radiation are similar. However, these interesting results were not followed up in the field. Given the importance and limitation of optogenetics, we are motivated to develop X-genetics, which is to have the same functionality of optogenetics with X-rays that penetrate tissues deeply and can be focused precisely. In this paper, we demonstrate our first recorded signals from dark-adapted frogs of the same type under both visible light stimulation and X-ray irradiation. Our results appear fairly consistent to the responses reported in the 1960s but further investigation is needed to calibrate the relationship between ERG responses and x-ray stimulation and to reveal the underlying mechanism.
Hengyong Yu*
In the biomedical imaging field, there are thousands of papers published annually that develop new algorithms for image processing, reconstruction, and analysis. However, few of those papers provide a fair and direct comparison between a proposed algorithm and its competing approaches.
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