Fluorescent X-ray Computed Tomography Research Articles

Feasibility of fluorescent X-ray computed tomography to verify the homogeneity of Mo/Gd contained in nuclear fuels: A Monte Carlo simulation

We studied the feasibility of a fluorescent X-ray computed tomography (FXCT) system to monitor the uniformity of nuclear fuels; this system could be used for research reactors or power reactors. In general, nuclear fuels contain non-fissile metals for various purposes. To avoid the use of high-enriched uranium (HEU) fuels, U–Mo alloy fuels have been studied to lower the enrichment factor and to enhance the uranium density of fuels to be used in research reactors. (U, Gd)O2 fuel is another uranium-metal alloy in which gadolinium (III) oxide (Gd2O3) powder is added to uranium dioxide (UO2) to adjust the reactivity of the fuel and enhance the performance of UO2. To guarantee the combustion stability of fuels in reactors, it is important to verify the homogeneity of alloy metals contained in the fuels. The FXCT system, which analyzes materials based on characteristic X-rays emitted from atoms, could be used to verify the homogeneity of the materials contained in nuclear fuels. External radiation sources are not necessary to induce characteristic X-rays from the fuel, as the gamma rays emitted from 235U stimulate the fuel atoms. To verify the feasibility of the system, we measured the energy spectrum of a UO2 pellet, in which small metal pieces of Gd and Mo were attached to the surface. Based on simulation studies, 2D and 3D radiographic images of UO2 fuels with Gd and Mo were reconstructed to verify the effectiveness of the FXCT system.

Thiol-Organosilica Particles Internally Functionalized with Propidium Iodide as a Multicolor Fluorescence and X-ray Computed Tomography Probe and Application for Non-Invasive Functional Gastrointestinal Tract Imaging

Propidium iodide (PI) is a fluorescent nucleic acid dye that contains iodide molecules. Thiol-organosilica particles that were internally functionalized with PI (PI particles) were prepared for X-ray computed tomography (CT) and multicolor fluorescence imaging. PI particles of various sizes were synthesized in a one-pot process. The particles showed unique fluorescent signals and X-ray absorption, with enhancement of the fluorescence intensity of PI located inside organosilica particles. PI particles had multicolor fluorescence, including original fluorescence and near-infrared (NIR). Orally administered PI particles were observed in the gastrointestinal tract (GIT) using fluorescent imaging devices and X-ray CT. An in vivo fluorescence imaging system could detect the NIR fluorescence of PI particles in the GIT specifically. Multipurpose zoom fluorescence microscopy was used to noninvasively visualize the real-time passage of particles and the movement of the GIT. The passage and distribution of particles over time in the GIT were demonstrated using X-ray CT. A correlation analysis between the fluorescent and X-ray CT data demonstrated the characteristics, limitations, and novel potential for noninvasive functional GIT dual modal imaging.

Visualization of age-dependent myocardial metabolic impairment in cardiomyopathic model hamster obtained by fluorescent X-ray computed tomography using I-127 BMIPP

Fluorescent X-ray computed tomography (FXCT) enables visualization of myocardial fatty acid metabolism by using non-radio-iodinated I-5-(p-iodophenyl)-3-(R,S)-methylpentadecanoice acid (BMIPP). In this experiment, age-dependent myocardial metabolic impairment was successfully imaged and analyzed quantitatively in J2N-k cardiomyopathic hamster using FXCT.

Preliminary quantitative analysis of myocardial fatty acid metabolism from fluorescent X-ray computed tomography imaging

Fluorescent X-ray computed tomography (FXCT) using synchrotron radiation reveals the cross-sectional distribution of specific elements in biomedical objects. The aim of this study was to investigate the feasibility of FXCT imaging to assess the myocardial metabolic state quantitatively. Hearts labelled with non-radioactive iodine myocardial fatty acid agent 15-p-(iodophenyl)-3-methylpentadecanoic acid (BMIPP) from cardiomyopathic and normal hamsters were imaged. FXCT images were compared with optical microscope images. Myocardial fatty acid metabolism enhanced with BMIPP was clearly depicted by FXCT, which showed an almost homogeneous image for normal and a heterogeneous image for cardiomyopathic hearts. Morphological structures of the heart such as the left ventricle and myocardial wall were also visualized by FXCT. Optical microscopy showed no fibrosis in normal and slight interstitial fibrosis in cardiomyopathic hearts. In the case of cardiomyopathy, the area of significantly reduced BMIPP uptake was 39% in the short axis of the mid-left ventricle in the FXCT image, whereas a slight interstitial fibrosis of around 12% was recognized by optical microscopy for the same slice. This result indicated that reduced BMIPP uptake was caused by the myocardial fatty acid metabolic abnormality, not by the fibrosis in cardiomyopathy. Thus, FXCT images might be used to assess the quantitative metabolic analysis in small animal models of heart diseases.

Improvement of imaging speed in fluorescent x‐ray computed tomography using synchrotron radiation

AbstractImproving the speed of fluorescent X‐ray CT imaging using synchrotron radiation has been studied from the points of view of the imaging system and the processing algorithm. Regarding the imaging system, high‐speed imaging at 2 seconds per point with a dead time of about 6% has been realized by incorporating an electronic system which operates stably in the high count rate region. In addition, the amounts of computation and memory required have been reduced to about 1/100 of the levels realized up to now by improving the efficiency of the reconstruction algorithm. The quantitative properties of this system have been confirmed by tests with a physical phantom and the iodine distribution has been estimated in in vitro human thyroid images. These results indicate the implementability of in vivo fluorescent X‐ray CT instrumentation. © 2002 Scripta Technica, Syst Comp Jpn, 33(2): 1–11, 2002

Integrated image presentation of transmission and fluorescent X-ray CT using synchrotron radiation

We have developed a computed tomography (CT) system with synchrotron radiation (SR) to detect fluorescent X-rays and transmitted X-rays simultaneously. Both SR transmission X-ray CT (SR-TXCT) and SR fluorescent X-ray CT (SR-FXCT) can describe cross-sectional images with high spatial and contrast resolutions as compared to conventional CT. TXCT gives morphological information and FXCT gives functional information of organs. So, superposed display system for SR-FXCT and SR-TXCT images has been developed for clinical diagnosis with higher reliability. Preliminary experiment with brain phantom was carried out and the superposition of both images was performed. The superposed SR–CT image gave us both functional and morphological information easily with high reliability, thus demonstrating the usefulness of this system.

Iodine imaging in thyroid by fluorescent X-ray CT with 0.05 mm spatial resolution

Fluorescent X-ray computed tomography (FXCT) at a 0.05 mm in-plane spatial resolution and 0.05 mm slice thickness depicted the cross sectional distribution of endogenous iodine within thyroid. The distribution obtained from the FXCT image correlated closely to that obtained from the pathological pictures.

Preliminary experiment of fluorescent X-ray computed tomography to detect dual agents for biological study

The simultaneous observation of various information, such as blood flow, tissue metabolism and distribution of receptors, is quite important in order to understand the functional state of biomedical objects. The simultaneous detectability of contrast agents by fluorescent X-ray computed tomography (FXCT) with synchrotron radiation is examined in this study. The system consisted of a silicon (111) double-crystal monochromator, an X-ray slit system, a scanning table, a PIN diode, a highly purified germanium detector and an X-ray charge-coupled device (CCD) camera. The monochromatic X-ray beam energy was adjusted to 37.0 keV and collimated into a pencil beam of 1 x 1 mm. The fluorescent spectra of the K alpha lines for iodine and xenon were detected simultaneously. FXCT could image the distribution of both iodine and xenon agents in a phantom clearly and the contrast ratio was significantly better than that of transmission X-ray computed tomography images.

Medical applications with synchrotron radiation in Japan.

In Japan, various medical applications of synchrotron X-ray imaging, such as angiography, monochromatic X-ray computed tomography (CT), radiography and radiation therapy, are being developed. In particular, coronary arteriography (CAG) is quite an important clinical application of synchrotron radiation. Using a two-dimensional imaging method, the first human intravenous CAG was carried out at KEK in May 1996; however, further improvements of image quality are required in clinical practice. On the other hand, two-dimensional aortographic CAG revealed canine coronary arteries as clearly as those on selective CAG, and coronary arteries less than 0.2 mm in diameter. Among applications of synchrotron radiation to X-ray CT, phase-contrast X-ray CT and fluorescent X-ray CT are expected to be very interesting future applications of synchrotron radiation. For actual clinical applications of synchrotron radiation, a medical beamline and a laboratory are now being constructed at SPring-8 in Harima.