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Your search keyword '"X-rays"' showing total 4 results
4 results on '"X-rays"'

1. FMT-PCCT: Hybrid Fluorescence Molecular Tomography—X-Ray Phase-Contrast CT Imaging of Mouse Models.

Author

Mohajerani, Pouyan, Hipp, Alexander, Willner, Marian, Marschner, Mathias, Trajkovic-Arsic, Marija, Ma, Xiaopeng, Burton, Neal C., Klemm, Uwe, Radrich, Karin, Ermolayev, Vladimir, Tzoumas, Stratis, Siveke, Jens T., Bech, Martin, Pfeiffer, Franz, and Ntziachristos, Vasilis

Subjects
*HYBRID systems, *FLUORESCENCE spectroscopy, *TOMOGRAPHY, *X-rays, *COMPUTED tomography, *LABORATORY mice, *MEDICAL imaging systems
Abstract

The implementation of hybrid fluorescence molecular tomography (FMT) and X-ray computed tomography (CT) has been shown to be a necessary development, not only for combining anatomical with functional and molecular contrast, but also for generating optical images of high accuracy. FMT affords highly sensitive 3-D imaging of fluorescence bio-distribution, but in stand-alone form it offers images of low resolution. It was shown that FMT accuracy significantly improves by considering anatomical priors from CT. Conversely, CT generally suffers from low soft tissue contrast. Therefore utilization of CT data as prior information in FMT inversion is challenging when different internal organs are not clearly differentiated. Instead, we combined herein FMT with emerging X-ray phase-contrast CT (PCCT). PCCT relies on phase shift differences in tissue to achieve soft tissue contrast superior to conventional CT. We demonstrate for the first time FMT-PCCT imaging of different animal models, where FMT and PCCT scans were performed in vivo and ex vivo, respectively. The results show that FMT-PCCT expands the potential of FMT in imaging lesions with otherwise low or no CT contrast, while retaining the cost benefits of CT and simplicity of hybrid device realizations. The results point to the most accurate FMT performance to date. [ABSTRACT FROM AUTHOR]

Published
2014
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2. Performance Evaluation and X-ray Dose Quantification for Various Scanning Protocols of the GE eXplore 120 Micro-CT.

Author

Bretin, Florian, Warnock, Geoffrey, Luxen, Andre, Plenevaux, Alain, Seret, Alain, and Bahri, Mohamed Ali

Subjects
*COMPUTED tomography, *IMAGE quality analysis, *MEDICAL imaging systems, *X-rays, *RADIATION dosimetry, *IMAGING phantoms
Abstract

The aim of this paper was to evaluate the performance of the General Electric eXplore 120 micro-CT regarding image quality and delivered dose of several protocols. Image quality (resolution, linearity, uniformity, and geometric accuracy) was assessed using the vmCT phantom developed for the GE eXplore Ultra, the QRM low contrast, and the QRM Bar Pattern Phantom. All dose measurements were performed using a mobileMOSFET dose verification system, and the CTDI100 and the multiple-scan average dose (MSAD) were determined with a custom-built PMMA phantom. Additionally, in vivo scans in sacrificed rats with different weights were acquired to assess dose, contrast, and resolution variation due to X-ray absorption in surrounding tissue. The spatial resolution was determined as between 95 and 138 \mum with a geometric accuracy of 0.1%. The system has a highly linear response to the iodine concentrations (0.937–30 mg/ml) for all protocols. The calculated CTDI100 ranged from 20.15 to 56.79 mGy, and the MSAD from 27.98 to 77.45 mGy. The results were confirmed by in vivo scans in rats with different weights, and no impact of body weight on delivered dose could be observed. However, body weight had a slight impact on image contrast and resolution. [ABSTRACT FROM AUTHOR]

Published
2013
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3. Tagging module for lesion localization in capsule endoscopy

Author

Tanq Shao Qiang, Nandar Su, Kripesh Vaidyanathan, Jayakrishnan Chandrappan, and Lim Ruiqi

Subjects
Endoscopes, Titanium, Silicon, Capsule Endoscopes, Endoscope, Swine, Computer science, X-Rays, Biocompatible Materials, Endoscopy, Equipment Design, Capsule Endoscopy, Gastrointestinal tract disorders, law.invention, Barium, Capsule endoscopy, law, Region of interest, Animals, Humans, Digestive tract, Intestinal Mucosa, Biomedical engineering
Abstract

Capsule endoscopes are effective diagnostic tools for the gastro intestinal tract disorders at patient's comfort. However the present capsule endoscopes lack efficient localization techniques to specify a pathological area that may require further diagnosis or treatment. This paper presents the development of a tagging module based novel method for the real-time localization of the site of interest. The tagging module consists of a bio compatible micro tag, compressed spring with a string latch and thermal igniter. The module can be integrated with the capsule endoscope and activated using an external trigger signal. On activation, the micro tag releases instantly and penetrates the mucosa layer of GI tract, region of interest. X-ray imaging is used to detect the location of micro tag embedded in GI tract wall. The radiopaque micro tags provide pre-operative valuable position information of the infected area to facilitate further clinical procedures.

Published
2010

4. X-ray forward-scatter imaging: experimental validation of model

Author

Robert J. Leclair and Paul C. Johns

Subjects
Photon, Materials science, Forward scatter, Biophysics, In Vitro Techniques, Biophysical Phenomena, Imaging phantom, Kerma, Optics, Animals, Humans, Scattering, Radiation, Radiometry, Physics, Photons, Beam diameter, Phantoms, Imaging, Scattering, business.industry, Muscles, X-Rays, Compton scattering, X-ray, Water, General Medicine, Models, Theoretical, Semiconductor detector, Liver, Ionization chamber, Cattle, business, Beam (structure)
Abstract

In our research program we have investigated, through modeling and related numerical calculations, the potential use of scatteredphotons for medical x-ray imaging. In this work, we present an experimental validation of the primary and of the forward-scatter x-ray imagingmodels. Incident polyenergetic photon beams generated from a conventional rotating anodex-ray tube were used. To compare quantitatively the results between primary and forward-scatter imaging, an ionization chamber was used to record the incident air collision kerma, K c air . Plots of contrast (C) and the signal-to-noise ratio(SNR) as a function of the imaging task are presented. We have chosen to make measurements with plastics [polymethyl methacrylate (PMMA), polycarbonate, polystyrene, polyethylene, and nylon] placed at the center of a 15 cm diam spherical water phantom. Good agreement between experiment (expt) and prediction (pred) was obtained for many imaging tasks. For example, to image a 2 cm thick PMMA/polycarbonate combination using an 80 kV beam with the primary photons we obtain C expt =0.01±0.02, C pred =0.008±0.002, SNR expt / K c air =0.86±1.6 (mJ/kg ) −1/2 and SNR pred / K c air =0.51±0.14 (mJ/kg ) −1/2 . The values obtained by using the θ=4° scattered field were C expt =0.26±0.06, C pred =0.19±0.01, SNR expt / K c air =3.8±0.8 (mJ/kg ) −1/2 , and SNR pred / K c air =3.2±0.3 (mJ/kg ) −1/2 . We have, however, shown that using form factor data from different authors can have a significant effect on the predicted values of C and SNR. The use of our semianalytic expressions for the numbers of transmitted and scatteredphotons combined with our experimental measurements allowed us to quantify the amount of water contamination in our measurements. Some preliminary results in air with biological materials (liver, muscle, water) are also presented. We are confident that our model can be used as a tool for designing and optimizing an x-rayscatterimaging system.

Published
2002

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