Diffraction Enhanced Imaging (DEI) is an x-ray phase contrast technique, which is showing great promise for a number of medical imaging problems. For a source it relies on a highly collimated flux of monochromatic x-rays, which is currently only available at synchrotron radiation facilities. Phase shifts occurring as the wave passes through the object are made visible using Bragg diffraction from a post-sample analyser optic. In early 2004 the DEI system on the bending-magnet beam line 7.6 of the Daresbury SRS was used for the first time to image a number of small medical specimens. This paper will report on the performance of the system and the results of these initial studies. A new DEI instrument is currently in the design phase. This facility will be integrated on wiggler station 9.4 on the SRS allowing access to shorter x-ray wavelengths and greater flux. A progress report on the design features and implementation of this system will be given.
Conventional x-ray imaging relies almost entirely on differences in the absorption of x-rays between tissues to produce contrast. While these differences are substantial between bone and soft tissue, they are very small between different soft tissue types resulting in poor visualization of soft tissues. Diffraction enhanced imaging (DEI) is currently in development by several groups as a new imaging modality that exploits information contained within the x- ray scattering distribution at low angles. We have used the SYRMEP beam line at the Elettra Synchrotron facility in Trieste, Italy to image a variety of tissue specimens, together with several phantoms. Mono-energetic photons in the range 17 keV to 25 keV were used with an analyzer crystal which diffracted the x-rays onto a detector. We have obtained some spectacular images which display remarkable contrast and resolution. The images can be processed to separate the pure absorption and pure refraction effects in a quantitative manner. These images demonstrate that DEI provides tissue morphology information not accessible with conventional radiographic imaging. The contrast caused primarily by refraction as the x-ray passes from one tissue type to another in the specimen is evident. Since x-ray refraction is much less energy dependent than absorption there is considerable potential for extremely low dose imaging. We believe that the potential of this technique is considerable and we present dat to illustrate the quality of the images.
Robert Lewis, Keith Rogers, Christopher Hall, Andrew Evans, Sarah Pinder, Ian Ellis, Alan Hufton, Elizabeth Towns-Andrews, Susan Slawson, David Dance, Caroline Boggis
We have performed small angle X-ray scattering measurements at the Synchrotron Radiation Source at Daresbury to make an initial assessment of the diagnostic information obtainable from various breast tissues. These experiments have indicated that high quality interpretable diffraction data can be rapidly produced from breast core cut biopsy specimens. We have demonstrated a remarkable and systematic difference between the X-ray scattering from normal, benign and malignant breast tissue collagen. Our findings indicate that it may be possible to use molecular structure characteristics of breast tissue as novel markers of disease progression.
John Goodby, Kenneth Toyne, Michael Hird, Peter Styring, R. Lewis, Andreas Beer, C. Dong, M. Glendenning, John Jones, K. Lymer, Andrew Slaney, Victoria Minter, L. Chan
Ferroelectric and antiferroelectric liquid crystals have shown great promise for use in large area flat panel displays because of their fast switching and bistable operation. However, the commercialization of FLCDs and AFLCDs using surface stabilized geometries has not materialized for a number of reasons, most notably shock instability, the need to control the cell spacing of the display to between 1 and 2 micrometer, and competition from actively addressed nematic displays. Surface stabilized displays are nevertheless finding niche markets in areas such as spatial light modulators, microdisplays, and projection systems. Even though this is the present situation, it is clear that FLCs and AFLCs will be used advantageously in the future in active matrix configurations to give LCDs that operate at video-frame rates. Furthermore, there are many emerging uses for such materials in the areas of photonics and sensors e.g., novel switching and wavelength filtering components based on liquid crystal phase modulators and filters. There is also interest in utilizing LC technology in fiber optic networks, telecommunication transmission systems, interconnecting networks in large computers, optical image processors, and optically accessible electronic memory structures. All of these applications require fast switching materials that are stable and non-absorbent to light of various wavelengths.
The RAPID detector system previously reported on in SPIE volume 2521, has successfully completed the final stage of its commissioning. During this period several of the Synchrotron Radiation Source User groups were invited to perform trial experiments with the new detector system. Over a period of one month in late 1998 several types of experiments were performed on the flagship small angle scattering station 16.1, ranging from polymer diffraction rheometry to time resolved muscle diffraction. The results and detector assessments from some of these experiments are presented. A discussion is made of refinements to the system which would further enhance its performance.
Robert Lewis, Keith Rogers, Christopher Hall, Elizabeth Towns-Andrews, Susan Slawson, Andrew Evans, Sarah Pinder, Ian Ellis, Caroline Boggis, Alan Hufton, David Dance
The most frequently occurring cancer in women is that of the breast where it accounts for almost 20% of all cancer deaths. The U.K. has the world's highest mortality rate from breast cancer with an increasing incidence of 25000 per annum. Characterizing the complex physiological and tissue changes that form the natural history of breast cancer is clearly important for understanding associated biological mechanisms and for diagnosis. We report the initial findings of a diffraction study of breast tissue collagen that we believe may be due to tumor genesis. Small angle, synchrotron X-ray scattering has enabled us to examine `core cut' biopsy specimens and characterize their collagen architecture. We present data that demonstrates possible structural differences between tumor and normal tissue. We discuss the implications of these findings in the context of using molecular structure characteristics as new and novel markers of disease progression.
The on- and off-axis imaging properties and effective area of the two SODART flight telescopes have been measured using the expanded beam x-ray facility at the Daresbury synchrotron. From on-axis measurements the encircled power distribution and the point spread function at three energies 6.627 keV, 8.837 keV and 11.046 keV have been measured using a one-dimensional position sensitive detector. We found that the point spread function can be presented well by a function which is a sum of a Gaussian divided by the radius and two exponential terms where the first has a 1/e value close to 2 arcmin and the other a 1/e value of ca. 15 arcmin. The data have been used to calculate the half power diameter (HPD) for three different SODART focal plane detectors, the high energy proportional counter (HEPC) with a field of view (FOV) of 65 arcmin, the low energy proportional counter (LEPC) with a FOV of 33 arcmin and the 19 element solid state detector array (SIXA) with a FOV of 18 arcmin. We found that the HPD decreases with increasing energy due to poorer figure of the outermost mirrors. The HPD falls in the range from 2.4 to 3.8 arcmin depending on energy and FOV. Data have also been obtained on the on- and off-axis effective area at all three energies and compared to that obtained from a raytracing of an ideal telescope configuration. We found that the measured on-axis effective area integrated over a FOV of 105 arcmin is ca. 65% of the area predicted from an ideal geometry. Finally the one- dimensional detector data has been used to obtain the radial dependence of the on-axis HPD and the on-axis effective area and the data from the two-dimensional position sensitive detector has been used to obtain the azimuthal dependence of the on-axis HPD and the on-axis effective area.
A proposal for an x-ray optics test facility based at a synchrotron radiation source is presented. The facility would incorporate a clean preparation area, and a large evacuable test area. The advantages of using a synchrotron as the source of the test radiation are discussed. These include the ability to produce a highly parallel beam of monochromatic x rays ranging from 200 eV to around 70 keV.
The MART-LIME is a large area x-ray experiment planned to be launched on board the Russian satellite Spectrum X-Gamma, as the high energy imager of a complement of broad band co- aligned x-ray telescopes. The energy range covered is 5 - 150 keV with an angular resolution of 8.6 arcminutes. The final detector configuration is now in its testing phase and includes the high pressure window comprising the 6 by 6 degree collimator, and the multiwire proportional counter (MWPC). The response to x-ray sources was investigated during the tests carried out at the Daresbury Laboratory (Warrington, UK) facilities The MWPC was filled up by a xenon-argon-isobutane gas mixture in order to evaluate the efficiency of the detector and in particular its linearity over the whole approximately 2,000 cm2 sensitive area. At the same time the various parts of the apparatus have been simulated by using a Monte Carlo program. Results on the detector response and simulations are presented.
We present the first results from two highly parallel detector systems designed for fast time resolved x-ray diffraction experiments. The readout systems have been designed to give throughputs well in excess of 107 events per second. The detector systems have been designed to allow high flux diffraction patterns to be collected with very much reduced rate effects when compared with previous designs. This has been achieved using wire microgap proportional counters coupled to multi-channel data acquisition systems. The efficiency and low noise of the detector coupled to the speed of the readout has produced a detector system capable of more fully exploiting the time resolved diffraction stations on the UK Synchrotron Radiation Source at the Daresbury Laboratory. Modifications to the design will be presented which will allow the system to cope with even higher count rates in the future.
The imaging properties of a test model of the SODART telescopes have been studied using an expanded beam X-ray facility at the Daresbury synchrotron. The encircled power and the point spread function at three energies 6.627 keV, 8.837 keV and 11.046 keV have been measured using 1D and 2D position sensitive detectors. The data have been used to calculate the Half Power Diameter (HPD) for three different SODART focal plane detectors. The High Energy Proportional Counter (HEPC), the Low Energy Proportional Counter (LEPC) and the 19 element solid state array detector (SIXA). At 6.627 keV and 8.837 keV the HPD is 2.5 - 3.0 arcmin for all detectors whereas it is somewhat larger at 11.046 keV for HEPC and LEPC but essentially unchanged for SIXA. Finally, the data are used to point to improvements that can be introduced during the manufacture of the flight telescopes.
A facility for the calibration of X-ray Space Instrumentation has been established for the Daresbury Synchrotron. The facility provides a continuously tunable beam with (Delta) (lambda) /(lambda) <EQ 10-4 in the energy range from approximately 5 kev to more than 20 kev. At selected energies in the interval from 6 kev to 12 kev, the facility features a 1D sheet of X-rays, approximately 200 mm wide, obtained from an extremely asymmetric reflection in large perfect crystals of Si. The beam is collimated to < 20 arcsec. Data from tests using large (approximately 250 mm long) beam expander crystals in the energy range from 6 - 12 kev are presented. The planned calibration of the two X-ray telescopes (XSPECT/SODART and JET-X) will be described.
FT-IR spectra have been measured for hydrogen bonded complexes in propionic acid in solution, o-acetyl salicyclic acid in solid and solution, and gelatin and collagen in which the repeating units, glycine, proline and hydroxyproline, give rise to amide and hydroxyl bands which were measured in solution and solids phases. The Chem-X computer modelling package (Chemical Design Ltd.) permits the measurement of interatomic distance and the calculation of the energy of the hydrogen bonded system by molecular mechanics methods. Using the JCAMP.DX file transfer protocol, spectra associated with these interactions are incorporated into the molecular modelling package to attempt direct correlation between a spectrum and the model of the interactions responsible for the measured information.
MART-LIME is a coded mask imaging telescope to be flown onboard the international observatory SPECTRUM X-(Gamma) in 1995. This high-energy instrument, the center of which is a high-pressure proportional counter sensitive to the 5 - 150 keV energy range, will be characterized by a limiting sensitivity of about 1 milliCrab for a 105 s observation period. The imaging capability of the instrument is provided by a coded-mask aperture system, used in conjunction with a position sensitive detector. The basic pattern of the coded aperture is a 71 X 73 URA mask (twin prime). With the addition of an outer frame comprising 18 pixels on each side, a fully coded field-of-view of 2.6 degree(s) X 2.6 degree(s) is obtained, while a partially coded field-of-view is achieved up to 6 degree(s). Test procedures used to determine the performance of the MART-LIME detector are discussed. Results showing the spectroscopic capabilities of a Laboratory-Prototype detector are presented.
The concept, operational principle, and test results are presented for a new type of high-pressure high-spatial resolution proportional counter with enhanced spectroscopic capability. The detector in its baseline configuration is to be filled with a xenon/quench gas mixture at 5 bar and is to be sensitive over the 5-150 eV energy range. The position resolution will range from 0.5 mm at the lower energies to around 1 mm at the upper end of the energy range. The very high timing resolution of this new detector allows high count rate capacity and enables the application of the escape gating technique to achieve a high spectral resolution at energies above the xenon K edge.
Grazing incidence x-ray optics for x-ray astronomical applications are used outside the earth's atmosphere. These devices require a large collection aperture and the imaging of an x-ray source that is essentially
placed at infinity. The ideal testing system for these optical elements has to approximate that encountered under working conditions; however, the testing of these optical elements is notoriously difficult with conventional x-ray generators. Synchrotron radiation (SR) sources are sufficiently brilliant to produce a nearly perfect parallel beam over a large area while still retaining a flux considerably higher than that available from conventional x-ray generators. A facility designed for the testing of x-ray optics, particularly in connection with x-ray telescopes, is described. It is proposed that this facility will be accommodated at the Synchrotron Radiation Source at the Daresbury Laboratory in the United Kingdom.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.