While large-scale synchrotron sources provide a highly brilliant monochromatic X-ray beam, these X-ray sources are expensive in terms of installation and maintenance, and require large amounts of space due to the size of storage rings for GeV electrons. On the other hand, laboratory X-ray tube sources can easily be implemented in laboratories or hospitals with comparatively little cost, but their performance features a lower brilliance and a polychromatic spectrum creates problems with beam hardening artifacts for imaging experiments. Over the last decade, compact synchrotron sources based on inverse Compton scattering have evolved as one of the most promising types of laboratory-scale X-ray sources: they provide a performance and brilliance that lie in between those of large-scale synchrotron sources and X-ray tube sources, with significantly reduced financial and spatial requirements. These sources produce X-rays through the collision of relativistic electrons with infrared laser photons. In this study, an analysis of the performance, such as X-ray flux, source size and spectra, of the first commercially sold compact light source, the Munich Compact Light Source, is presented.
Here we introduce a new concept for x-ray computed tomography that yields information about the local micro-morphology and its orientation in each voxel of the reconstructed 3D tomogram. Contrary to conventional x-ray CT, which only reconstructs a single scalar value for each point in the 3D image, our approach provides a full scattering tensor with multiple independent structural parameters in each volume element. In the application example shown in this study, we highlight that our method can visualize sub-pixel fiber orientations in a carbon composite sample, hence demonstrating its value for non-destructive testing applications. Moreover, as the method is based on the use of a conventional x-ray tube, we believe that it will also have a great impact in the wider range of material science investigations and in future medical diagnostics.
Between X-ray tubes and large-scale synchrotron sources, a large gap in performance exists with respect to the monochromaticity and brilliance of the X-ray beam. However, due to their size and cost, large-scale synchrotrons are not available for more routine applications in small and medium-sized academic or industrial laboratories. This gap could be closed by laser-driven compact synchrotron light sources (CLS), which use an infrared (IR) laser cavity in combination with a small electron storage ring. Hard X-rays are produced through the process of inverse Compton scattering upon the intersection of the electron bunch with the focused laser beam. The produced X-ray beam is intrinsically monochromatic and highly collimated. This makes a CLS well-suited for applications of more advanced--and more challenging--X-ray imaging approaches, such as X-ray multimodal tomography. Here we present, to our knowledge, the first results of a first successful demonstration experiment in which a monochromatic X-ray beam from a CLS was used for multimodal, i.e., phase-, dark-field, and attenuation-contrast, X-ray tomography. We show results from a fluid phantom with different liquids and a biomedical application example in the form of a multimodal CT scan of a small animal (mouse, ex vivo). The results highlight particularly that quantitative multimodal CT has become feasible with laser-driven CLS, and that the results outperform more conventional approaches.phase-contrast tomography | dark-field tomography | grating interferometer | inverse Compton X-rays | X-ray imaging W ith the introduction of the grating interferometer (1-3), the field of X-ray phase-contrast imaging has seen great advances in the past decade. In comparison with conventional attenuation-contrast imaging, the phase-contrast modality greatly improves soft-tissue contrast, which can, for example, be used for better tumor visualization (4). With the development of the TalbotLau interferometer, grating-based phase-contrast imaging has become feasible not only with synchrotron sources, but also with standard X-ray tube sources (3, 5). On the downside, the visibility is degraded due to the broad polychromatic spectrum of the X-ray tube sources, thus compromising the image quality. Brilliant and highly monochromatic synchrotron sources yield superior results for high-resolution and high-sensitivity measurements (2, 4, 6-13).However, limited availability, high cost, and small fields of view make synchrotron sources incompatible with clinical applications or preclinical research on, e.g., small-animal disease models in close vicinity to biomedical laboratories with small-animal infrastructure. Offering a monochromatic beam as well as higher brilliance and coherence than X-ray tube sources, compact synchrotron sources can be classified between tube sources and synchrotron sources. These features are achieved with a compact light source (CLS), which has a size that is compatible with conventional laboratories, making it an interesting candidate for preclinical and mater...
X-ray coronary angiography is an invaluable tool for the diagnosis of coronary artery disease. However, the use of iodine-based contrast media can be contraindicated for patients who present with chronic renal insufficiency or with severe iodine allergy. These patients could benefit from a reduced contrast agent concentration, possibly achieved through application of a mono-energetic x-ray beam. While large-scale synchrotrons are impractical for daily clinical use, the technology of compact synchrotron sources strongly advanced during the last decade. Here we present a quantitative analysis of the benefits a compact synchrotron source can offer in coronary angiography. Simulated projection data from quasi-mono-energetic and conventional x-ray tube spectra is used for a CNR comparison. Results show that compact synchrotron spectra would allow for a significant reduction of contrast media. Experimentally, we demonstrate the feasibility of coronary angiography at the Munich Compact Light Source, the first commercial installation of a compact synchrotron source.X-ray imaging is an invaluable diagnostic tool in clinical practice. While conventional x-ray tubes are well established and reliable in clinical x-ray imaging, their broad bremsstrahlung spectra impose a number of drawbacks with respect to image quality. The polychromatic spectrum can introduce beam hardening artifacts or impede the aim to optimize both the dose level and the image quality, as the x-ray energy cannot be tuned directly to the desired range. On the other hand, 3rd generation synchrotron sources offer highly brilliant and monochromatic x-ray beams, but their high spatial and financial demands make their clinical use impracticable. To close this performance gap, new types of x-ray sources have been investigated throughout the last decades. One possibility are compact light sources (CLS) based on inverse Compton scattering 1 , which provide a quasi-mono-energetic, tunable and partially coherent x-ray beam. The first commercially sold system has only recently been installed in Munich, Germany 2 .One of the clinical applications that could benefit significantly from a mono-energetic x-ray beam is coronary angiography, as it relies on contrast media application. A mono-energetic x-ray beam could thoroughly exploit the sudden increase of the absorption coefficient of a contrast medium at its K-edge.Coronary angiography is an invaluable tool for the diagnosis of coronary disease. Complications are frequently associated with the high amount of iodine-based contrast media that are injected during the catheterization procedure. Especially for patients presenting with pre-existing renal insufficiency, there is a high risk to suffer from renal failure due to nephrotoxic effects of iodine-based contrast agents, resulting in severe renal dysfunction and a high risk of subsequent dialysis treatment 3-6 . In addition, several patients show allergic reactions following iodine injection, with the life-threatening risk of anaphylaxis 6 . A high amount of iodine c...
With the introduction of screening mammography, the mortality rate of breast cancer has been reduced throughout the last decades. However, many women undergo unnecessary subsequent examinations due to inconclusive diagnoses from mammography. Two pathways appear especially promising to reduce the number of false-positive diagnoses. In a clinical study, mammography using synchrotron radiation was able to clarify the diagnosis in the majority of inconclusive cases. The second highly valued approach focuses on the application of phase-sensitive techniques such as grating-based phase-contrast and dark-field imaging. Feasibility studies have demonstrated a promising enhancement of diagnostic content, but suffer from dose concerns. Here we present dose-compatible grating-based phase-contrast and dark-field images as well as conventional absorption images acquired with monochromatic x-rays from a compact synchrotron source based on inverse Compton scattering. Images of freshly dissected mastectomy specimens show improved diagnostic content over ex-vivo clinical mammography images at lower or equal dose. We demonstrate increased contrast-to-noise ratio for monochromatic over clinical images for a well-defined phantom. Compact synchrotron sources could potentially serve as a clinical second level examination.
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