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Sample records for free-breathing abdominal phase-contrast

  1. Dual registration of abdominal motion for motility assessment in free-breathing data sets acquired using dynamic MRI

    NASA Astrophysics Data System (ADS)

    Menys, A.; Hamy, V.; Makanyanga, J.; Hoad, C.; Gowland, P.; Odille, F.; Taylor, S. A.; Atkinson, D.

    2014-08-01

    At present, registration-based quantification of bowel motility from dynamic MRI is limited to breath-hold studies. Here we validate a dual-registration technique robust to respiratory motion for the assessment of small bowel and colonic motility. Small bowel datasets were acquired in breath-hold and free-breathing in 20 healthy individuals. A pre-processing step using an iterative registration of the low rank component of the data was applied to remove respiratory motion from the free breathing data. Motility was then quantified with an existing optic-flow (OF) based registration technique to form a dual-stage approach, termed Dual Registration of Abdominal Motion (DRAM). The benefit of respiratory motion correction was assessed by (1) assessing the fidelity of automatically propagated segmental regions of interest (ROIs) in the small bowel and colon and (2) comparing parametric motility maps to a breath-hold ground truth. DRAM demonstrated an improved ability to propagate ROIs through free-breathing small bowel and colonic motility data, with median error decreased by 90% and 55%, respectively. Comparison between global parametric maps showed high concordance between breath-hold data and free-breathing DRAM. Quantification of segmental and global motility in dynamic MR data is more accurate and robust to respiration when using the DRAM approach.

  2. Effects of arterial blood flow on walls of the abdominal aorta: distributions of wall shear stress and oscillatory shear index determined by phase-contrast magnetic resonance imaging.

    PubMed

    Sughimoto, Koichi; Shimamura, Yoshiaki; Tezuka, Chie; Tsubota, Ken'ichi; Liu, Hao; Okumura, Kenichiro; Masuda, Yoshitada; Haneishi, Hideaki

    2016-07-01

    Although abdominal aortic aneurysms (AAAs) occur mostly inferior to the renal artery, the mechanism of the development of AAA in relation to its specific location is not yet clearly understood. The objective of this study was to evaluate the hypothesis that even healthy volunteers may manifest specific flow characteristics of blood flow and alter wall shear or oscillatory shear stress in the areas where AAAs commonly develop. Eight healthy male volunteers were enrolled in this prospective study, aged from 24 to 27. Phase-contrast magnetic resonance imaging (MRI) was performed with electrocardiographic triggering. Flow-sensitive four-dimensional MR imaging of the abdominal aorta, with three-directional velocity encoding, including simple morphological image acquisition, was performed. Information on specific locations on the aortic wall was applied to the flow encodes to calculate wall shear stress (WSS) and oscillatory shear index (OSI). While time-framed WSS showed the highest peak of 1.14 ± 0.25 Pa in the juxtaposition of the renal artery, the WSS plateaued to 0.61 Pa at the anterior wall of the abdominal aorta. The OSI peaked distal to the renal arteries at the posterior wall of the abdominal aorta of 0.249 ± 0.148, and was constantly elevated in the whole abdominal aorta at more than 0.14. All subjects were found to have elevated OSI in regions where AAAs commonly occur. These findings indicate that areas of constant peaked oscillatory shear stress in the infra-renal aorta may be one of the factors that lead to morphological changes over time, even in healthy individuals. PMID:26481791

  3. A free-breathing lung motion model

    NASA Astrophysics Data System (ADS)

    Zhao, Tianyu

    Lung cancer has been the leading cause of cancer deaths for decades in the United States. Although radiotherapy is one of the most effective treatments, side effects from error in delivery of radiation due to organ motion during breathing remain a significant issue. To compensate the breathing motion during the treatment, a free breathing lung motion model, x= x0+αv+betaf, was developed and discussed, where x is the position of a piece of tissue located at reference position x0. α is a parameter which characterizes the motion due to local air filling (motion as a function of tidal volume) and beta is the parameter that accounts for the motion due to the imbalance of dynamical stress distributions during inspiration and exhalation which cause lung motion hysteresis (motion as a function of airflow). The parameters α and beta together provide a quantitative characterization of breathing motion that inherently includes the complex hysteresis interplay. The theoretical foundation of the model was built by investigating the stress distribution inside of a lung and the biomechanical properties of the lung tissues. Accuracy of the model was investigated by using 49 free-breathing patient data sets. Applications of the model in localizing lung cancer, monitoring radiation damage and suppressing artifacts in free-breathing PET images were also discussed. This work supported in part by NIHR01CA096679 and NIHR01CA116712.

  4. Compressive phase contrast tomography

    NASA Astrophysics Data System (ADS)

    Maia, F.; MacDowell, A.; Marchesini, S.; Padmore, H. A.; Parkinson, D. Y.; Pien, J.; Schirotzek, A.; Yang, C.

    2010-08-01

    When x-rays penetrate soft matter, their phase changes more rapidly than their amplitude. Interference effects visible with high brightness sources creates higher contrast, edge enhanced images. When the object is piecewise smooth (made of big blocks of a few components), such higher contrast datasets have a sparse solution. We apply basis pursuit solvers to improve SNR, remove ring artifacts, reduce the number of views and radiation dose from phase contrast datasets collected at the Hard X-Ray Micro Tomography Beamline at the Advanced Light Source. We report a GPU code for the most computationally intensive task, the gridding and inverse gridding algorithm (non uniform sampled Fourier transform).

  5. Compressive Phase Contrast Tomography

    SciTech Connect

    Maia, Filipe; MacDowell, Alastair; Marchesini, Stefano; Padmore, Howard A.; Parkinson, Dula Y.; Pien, Jack; Schirotzek, Andre; Yang, Chao

    2010-09-01

    When x-rays penetrate soft matter, their phase changes more rapidly than their amplitude. Interference effects visible with high brightness sources creates higher contrast, edge enhanced images. When the object is piecewise smooth (made of big blocks of a few components), such higher contrast datasets have a sparse solution. We apply basis pursuit solvers to improve SNR, remove ring artifacts, reduce the number of views and radiation dose from phase contrast datasets collected at the Hard X-Ray Micro Tomography Beamline at the Advanced Light Source. We report a GPU code for the most computationally intensive task, the gridding and inverse gridding algorithm (non uniform sampled Fourier transform).

  6. Phase Contrast Imaging

    SciTech Connect

    Menk, Ralf Hendrik

    2008-11-13

    All standard (medical) x-ray imaging technologies, rely primarily on the amplitude properties of the incident radiation, and do not depend on its phase. This is unchanged since the discovery by Roentgen that the intensity of an x-ray beam, as measured by the exposure on a film, was related to the relative transmission properties of an object. However, recently various imaging techniques have emerged which depend on the phase of the x-rays as well as the amplitude. Phase becomes important when the beam is coherent and the imaging system is sensitive to interference phenomena. Significant new advances have been made in coherent optic theory and techniques, which now promise phase information in medical imaging. The development of perfect crystal optics and the increasing availability of synchrotron radiation facilities have contributed to a significant increase in the application of phase based imaging in materials and life sciences. Unique source characteristics such as high intensity, monochromaticity, coherence and high collimating provide an ideal source for advanced imaging. Phase contrast imaging has been applied in both projection and computed tomography modes, and recent applications have been made in the field of medical imaging. Due to the underlying principle of X-ray detection conventional image receptors register only intensities of wave fields and not their phases. During the last decade basically five different methods were developed that translate the phase information into intensity variations. These methods are based on measuring the phase shift {phi} directly (using interference phenomena), the gradient {nabla}{sub {phi}}, or the Laplacian {nabla}{sup 2}{phi}. All three methods can be applied to polychromatic X-ray sources keeping in mind that the native source is synchrotron radiation, featuring monochromatic and reasonable coherent X-ray beams. Due to the vast difference in the coefficients that are driven absorption and phase effects (factor 1

  7. Free-Breathing Phase Contrast MRI with Near 100% Respiratory Navigator Efficiency using k-space Dependent Respiratory Gating

    PubMed Central

    Akçakaya, Mehmet; Gulaka, Praveen; Basha, Tamer A.; Ngo, Long H.; Manning, Warren J.; Nezafat, Reza

    2013-01-01

    Purpose To investigate the efficacy of a novel respiratory motion scheme, where only the center of k-space is gated using respiratory navigators, versus a fully respiratory-gated acquisition for 3D flow imaging. Methods 3D flow images were acquired axially using a GRE sequence in a volume covering the ascending and descending aorta, and the pulmonary artery bifurcation in 12 healthy subjects (33.2±15.8 years; 5 men). For respiratory motion compensation, two gating & tracking strategies were used with a 7mm gating window: 1) All of k-space acquired within the gating window (fully-gated), 2) Central k-space acquired within the gating window, and the remainder of k-space acquired without any gating (center-gated). Each scan was repeated twice. Stroke volume, mean flow, peak velocity and signal-to-noise-ratio measurements were performed both on the ascending and the descending aorta for all acquisitions, which were compared using a linear mixed-effects model and Bland-Altman analysis. Results There were no statistical differences between the fully-gated and center-gated strategies for the quantification of stroke volume, peak velocity and mean flow, as well as the signal-to-noise-ratio measurements. Furthermore, the proposed center-gated strategy had significantly shorter acquisition time compared to the fully-gated strategy (13:19±3:02 vs. 19:35±5:02, P<0.001). Conclusions The proposed novel center-gated strategy for 3D flow MRI allows for markedly shorter acquisition time without any systematic variation in quantitative flow measurements in this small group of healthy volunteers. PMID:23900942

  8. Feasibility of Free-breathing CCTA using 256-MDCT.

    PubMed

    Liu, Zhuo; Sun, Ye; Zhang, Zhuolu; Chen, Lei; Hong, Nan

    2016-07-01

    Usually, coronary computed tomography angiography (CCTA) is performed during breath-holding to reduce artifact caused by respiration. The objective of this study was to evaluate the feasibility of free-breathing CCTA compared to breath-holding using CT scanner with wide detector. To evaluate the feasibility of CCTA during free-breathing using a 256-MDCT. In 80 patients who underwent CCTA, 40 were performed during breath-holding (group A), and the remaining 40 during free-breathing (group B). The quality scores for coronary arteries were analyzed and defined as: 3 (excellent), 2 (good), and 1 (poor). The image noise, signal-to-noise ratio and effective radiation dose as well as the heart rate variation were compared. The noise, signal-to-noise ratio, and effective radiation dose were not significantly different between the 2 groups. The mean heart rate variation between planning and scanning for group A was 7 ± 7.6 bpm, and larger than 3 ± 2.6 bpm for group B (P = 0.012). Quality scores of the free-breathing group were better than those of the breath-holding group (group A: 2.55 ± 0.64, group B: 2.85 ± 0.36, P = 0.018). Free-breathing CCTA is feasible on wide detector CT scanner to provide acceptable image quality with reduced heart rate variation and better images for certain patients. PMID:27399104

  9. Surface metrology by phase contrast

    NASA Astrophysics Data System (ADS)

    Baker, Lionel R.

    1990-08-01

    Increasing use of electrooptical imaging and detection systems in thermography high density information storage laser instrumentation and X-ray optics has led to a pressing need for machinecompatible sensors for the measurement of surface texture. This paper reviews recent advances in the use of deterministic and parametric noncontact methods for texture measurement and justifies the need for objective simple and yet precise means for displaying the microfinish of a machined surface. The design of a simple two channel phase contrast microscope is described which can be calibrated by test pieces and used as a means for optimising the process parameters involved in the generation of high quality surfaces. Typical results obtained with this technique including dynamic range and ultimate sensitivity are discussed. 1 . NEED FOR SURFACE METROLOGY Surface quality has a direct influence on product acceptability in many different industries including those concerned with optoelectronics and engineering. The influence may be cosmetic as with paint finish on a motor car body or functional for example when excessive wear rates may occur in a bearing surface with inadequate oil retention. Since perfection can never be achieved and overspecification can be costly it is clearly necessary to be able to define thresholds of acceptance in relation to different situations. Such thresholds do of course require agreed methods of measurement with traceability to national standards. The current trends in surface metrology are towards higher

  10. Free-breathing conformal irradiation of pancreatic cancer.

    PubMed

    Solla, Ignazio; Zucca, Sergio; Possanzini, Marco; Piras, Sara; Pusceddu, Claudio; Porru, Sergio; Meleddu, Gianfranco; Farace, Paolo

    2013-01-01

    The purpose of this study was to assess treatment margins in free-breathing irradiation of pancreatic cancer after bone alignment, and evaluate their impact on conformal radiotherapy. Fifteen patients with adenocarcinoma of the head of the pancreas underwent implantation of single fiducial marker. Intrafraction uncertainties were assessed on simulation four-dimensional computed tomography (4D CT) by calculating maximal intrafraction fiducial excursion (MIFE). In the first ten patients, after bony alignment, the position of the fiducial was identified on weekly acquired megavolt cone-beam CT (MV-CBCT). The interfraction residual uncertainties were estimated by measuring the fiducial displacements with respect to the position in the first session. Patient mean (pM) and patient standard deviation (pSD) of fiducial displacement, mean (μM) and standard deviation (μSD) of pM, and root-mean-square of pSD (σ(res)) were calculated. In the other five patients, MIFE was added to the residual component to obtain personalized margin. In these patients, conformal kidney sparing (CONKISS) irradiation was planned prescribing 54/45 Gy to PTV1/PTV2. The organ-at-risk limits were set according to current NCCN recommendation. No morbidity related to the fiducial marker implantation was recorded. In the first ten patients, along right-left, anterior-posterior, and inferior-superior directions, MIFE was variable (mean ± std = 0.24 ± 0.13 cm, 0.31 ± 0.14 cm, 0.83 ± 0.35 cm, respectively) and was at most 0.51, 0.53, and 1.56 cm, respectively. Along the same directions, μM were 0.09, -0.05, -0.05 cm, μSD were 0.30, 0.17, 0.33 cm, and σ(res) were 0.35, 0.26, and 0.30 cm, respectively. MIFE was not correlated with pM and pSD. In the five additional patients, it was possible to satisfy recommended dose limits, with the exception of slightly higher doses to small bowel. After bony alignment, the margins for target expansion can be obtained by adding personalized MIFE to the residual

  11. Phase contrast imaging of cochlear soft tissue.

    SciTech Connect

    Smith, S.; Hwang, M.; Rau, C.; Fishman, A.; Lee, W.; Richter, C.

    2011-01-01

    A noninvasive technique to image soft tissue could expedite diagnosis and disease management in the auditory system. We propose inline phase contrast imaging with hard X-rays as a novel method that overcomes the limitations of conventional absorption radiography for imaging soft tissue. In this study, phase contrast imaging of mouse cochleae was performed at the Argonne National Laboratory Advanced Photon Source. The phase contrast tomographic reconstructions show soft tissue structures of the cochlea, including the inner pillar cells, the inner spiral sulcus, the tectorial membrane, the basilar membrane, and the Reissner's membrane. The results suggest that phase contrast X-ray imaging and tomographic techniques hold promise to noninvasively image cochlear structures at an unprecedented cellular level.

  12. Kidney motion during free breathing and breath hold for MR-guided radiotherapy

    NASA Astrophysics Data System (ADS)

    Stam, Mette K.; van Vulpen, Marco; Barendrecht, Maurits M.; Zonnenberg, Bernard A.; Intven, Martijn; Crijns, Sjoerd P. M.; Lagendijk, Jan J. W.; Raaymakers, Bas W.

    2013-04-01

    Current treatments for renal cell carcinoma have a high complication rate due to the invasiveness of the treatment. With the MRI-linac it may be possible to treat renal tumours non-invasively with high-precision radiotherapy. This is expected to reduce complications. To deliver a static dose distribution, radiation gating will be used. In this study the reproducibility and efficiency of free breathing gating and a breath hold treatment of the kidney was investigated. For 15 patients with a renal lesion the kidney motion during 2 min of free breathing and 10 consecutive expiration breath holds was studied with 2D cine MRI. The variability in kidney expiration position and treatment efficiency for gating windows of 1 to 20 mm was measured for both breathing patterns. Additionally the time trend in free breathing and the variation in expiration breath hold kidney position with baseline shift correction was determined. In 80% of the patients the variation in expiration position during free breathing is smaller than 2 mm. No clinically relevant time trends were detected. The variation in expiration breath hold is for all patients larger than the free breathing expiration variation. Gating on free breathing is, for gating windows of 1 to 5 mm more efficient than breath hold without baseline correction. When applying a baseline correction to the breath hold it increases the treatment efficiency. The kidney position is more reproducible in expiration free breathing than non-guided expiration breath hold. For small gating windows it is also more time efficient. Since free breathing also seems more comfortable for the patients it is the preferred breathing pattern for MRI-Linac treatments of the kidney.

  13. Toward Clinically Compatible Phase-Contrast Mammography

    PubMed Central

    Scherer, Kai; Willer, Konstantin; Gromann, Lukas; Birnbacher, Lorenz; Braig, Eva; Grandl, Susanne; Sztrókay-Gaul, Anikó; Herzen, Julia; Mayr, Doris; Hellerhoff, Karin; Pfeiffer, Franz

    2015-01-01

    Phase-contrast mammography using laboratory X-ray sources is a promising approach to overcome the relatively low sensitivity and specificity of clinical, absorption-based screening. Current research is mostly centered on identifying potential diagnostic benefits arising from phase-contrast and dark-field mammography and benchmarking the latter with conventional state-of-the-art imaging methods. So far, little effort has been made to adjust this novel imaging technique to clinical needs. In this article, we address the key points for a successful implementation to a clinical routine in the near future and present the very first dose-compatible and rapid scan-time phase-contrast mammograms of both a freshly dissected, cancer-bearing mastectomy specimen and a mammographic accreditation phantom. PMID:26110618

  14. X-ray phase-contrast methods

    SciTech Connect

    Lider, V. V. Kovalchuk, M. V.

    2013-11-15

    This review is devoted to a comparative description of the methods for forming X-ray phase-contrast images of weakly absorbing (phase) objects. These include the crystal interferometer method, the Talbot interferometer method, diffraction-enhanced X-ray imaging, and the in-line method. The potential of their practical application in various fields of science and technology is discussed. The publications on the development and optimization of X-ray phase-contrast methods and the experimental study of phase objects are analyzed.

  15. Phase-contrast and holographic computed laminography

    SciTech Connect

    Helfen, L.; Baumbach, T.; Cloetens, P.; Baruchel, J.

    2009-03-09

    In-line phase contrast is combined with laminography to image in three dimensions regions of interest in laterally extended flat specimens of weak absorption contrast. The principle of the method and a theoretical description of the imaging process are outlined. The present instrumental implementation enables reconstructing nondestructively the internal structure at different lateral specimen positions with micron resolution. The feasibility and application potential are demonstrated for both phase-contrast and holographic (i.e., using phase retrieval) laminography by the three-dimensional imaging of fuel-cell diffusion layers.

  16. Phase-contrast and holographic computed laminography

    NASA Astrophysics Data System (ADS)

    Helfen, L.; Baumbach, T.; Cloetens, P.; Baruchel, J.

    2009-03-01

    In-line phase contrast is combined with laminography to image in three dimensions regions of interest in laterally extended flat specimens of weak absorption contrast. The principle of the method and a theoretical description of the imaging process are outlined. The present instrumental implementation enables reconstructing nondestructively the internal structure at different lateral specimen positions with micron resolution. The feasibility and application potential are demonstrated for both phase-contrast and holographic (i.e., using phase retrieval) laminography by the three-dimensional imaging of fuel-cell diffusion layers.

  17. Phased Contrast X-Ray Imaging

    ScienceCinema

    Erin Miller

    2012-12-31

    The Pacific Northwest National Laboratory is developing a range of technologies to broaden the field of explosives detection. Phased contrast X-ray imaging, which uses silicon gratings to detect distortions in the X-ray wave front, may be applicable to mail or luggage scanning for explosives; it can also be used in detecting other contraband, small-parts inspection, or materials characterization.

  18. Reconstruction methods for phase-contrast tomography

    SciTech Connect

    Raven, C.

    1997-02-01

    Phase contrast imaging with coherent x-rays can be distinguished in outline imaging and holography, depending on the wavelength {lambda}, the object size d and the object-to-detector distance r. When r << d{sup 2}{lambda}, phase contrast occurs only in regions where the refractive index fastly changes, i.e. at interfaces and edges in the sample. With increasing object-to-detector distance we come in the area of holographic imaging. The image contrast outside the shadow region of the object is due to interference of the direct, undiffracted beam and a beam diffracted by the object, or, in terms of holography, the interference of a reference wave with the object wave. Both, outline imaging and holography, offer the possibility to obtain three dimensional information of the sample in conjunction with a tomographic technique. But the data treatment and the kind of information one can obtain from the reconstruction is different.

  19. Phase contrast portal imaging using synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Umetani, K.; Kondoh, T.

    2014-07-01

    Microbeam radiation therapy is an experimental form of radiation treatment with great potential to improve the treatment of many types of cancer. We applied a synchrotron radiation phase contrast technique to portal imaging to improve targeting accuracy for microbeam radiation therapy in experiments using small animals. An X-ray imaging detector was installed 6.0 m downstream from an object to produce a high-contrast edge enhancement effect in propagation-based phase contrast imaging. Images of a mouse head sample were obtained using therapeutic white synchrotron radiation with a mean beam energy of 130 keV. Compared to conventional portal images, remarkably clear images of bones surrounding the cerebrum were acquired in an air environment for positioning brain lesions with respect to the skull structure without confusion with overlapping surface structures.

  20. Phase contrast portal imaging using synchrotron radiation

    SciTech Connect

    Umetani, K.; Kondoh, T.

    2014-07-15

    Microbeam radiation therapy is an experimental form of radiation treatment with great potential to improve the treatment of many types of cancer. We applied a synchrotron radiation phase contrast technique to portal imaging to improve targeting accuracy for microbeam radiation therapy in experiments using small animals. An X-ray imaging detector was installed 6.0 m downstream from an object to produce a high-contrast edge enhancement effect in propagation-based phase contrast imaging. Images of a mouse head sample were obtained using therapeutic white synchrotron radiation with a mean beam energy of 130 keV. Compared to conventional portal images, remarkably clear images of bones surrounding the cerebrum were acquired in an air environment for positioning brain lesions with respect to the skull structure without confusion with overlapping surface structures.

  1. Phase contrast in high resolution electron microscopy

    DOEpatents

    Rose, H.H.

    1975-09-23

    This patent relates to a device for developing a phase contrast signal for a scanning transmission electron microscope. The lens system of the microscope is operated in a condition of defocus so that predictable alternate concentric regions of high and low electron density exist in the cone of illumination. Two phase detectors are placed beneath the object inside the cone of illumination, with the first detector having the form of a zone plate, each of its rings covering alternate regions of either higher or lower electron density. The second detector is so configured that it covers the regions of electron density not covered by the first detector. Each detector measures the number of electrons incident thereon and the signal developed by the first detector is subtracted from the signal developed by the record detector to provide a phase contrast signal. (auth)

  2. Differential phase contrast: An integral perspective

    NASA Astrophysics Data System (ADS)

    Lubk, A.; Zweck, J.

    2015-02-01

    Differential phase contrast (DPC) in a scanning transmission electron microscope is a widely employed technique for probing electromagnetic fields on the nanoscale. We show that the DPC signal corresponds to the averaged lateral probability current of the scattered electron probe. Based on this result we discuss the interpretation of DPC in terms of the projected electric and magnetic fields and the influence of experimental parameters thereon. We further show that DPC can be interpreted as a quantum weak measurement and that the reciprocal broad beam illumination technique is given by an astigmatic transport of intensity reconstruction.

  3. Gated CT imaging using a free-breathing respiration signal from flow-volume spirometry

    SciTech Connect

    D'Souza, Warren D.; Kwok, Young; Deyoung, Chad; Zacharapoulos, Nicholas; Pepelea, Mark; Klahr, Paul; Yu, Cedric X.

    2005-12-15

    Respiration-induced tumor motion is known to cause artifacts on free-breathing spiral CT images used in treatment planning. This leads to inaccurate delineation of target volumes on planning CT images. Flow-volume spirometry has been used previously for breath-holds during CT scans and radiation treatments using the active breathing control (ABC) system. We have developed a prototype by extending the flow-volume spirometer device to obtain gated CT scans using a PQ 5000 single-slice CT scanner. To test our prototype, we designed motion phantoms to compare image quality obtained with and without gated CT scan acquisition. Spiral and axial (nongated and gated) CT scans were obtained of phantoms with motion periods of 3-5 s and amplitudes of 0.5-2 cm. Errors observed in the volume estimate of these structures were as much as 30% with moving phantoms during CT simulation. Application of motion-gated CT with active breathing control reduced these errors to within 5%. Motion-gated CT was then implemented in patients and the results are presented for two clinical cases: lung and abdomen. In each case, gated scans were acquired at end-inhalation, end-exhalation in addition to a conventional free-breathing (nongated) scan. The gated CT scans revealed reduced artifacts compared with the conventional free-breathing scan. Differences of up to 20% in the volume of the structures were observed between gated and free-breathing scans. A comparison of the overlap of structures between the gated and free-breathing scans revealed misalignment of the structures. These results demonstrate the ability of flow-volume spirometry to reduce errors in target volumes via gating during CT imaging.

  4. Nonlinear phase contrast using a bacteriorhodopsin film

    NASA Astrophysics Data System (ADS)

    Iturbe Castillo, Marcelo D.; Sanchez-de-la-Llave, J. D.; Ramos Garcia, Ruben; Tepichin-Rodriguez, Eduardo; Olivos-Perez, L. I.

    2002-11-01

    In this paper we demonstrate a novel phase contrast system that employs a BR film. Since the filter is optically induced by the Fourier transform of the phase object, no alignment is necessary at the filter plane making it extremely robust. Due to the optical properties of BR films the phase filter can be induced with low light intensity levels. The material response allows operation at video frame rates, processing of high spatial resolution objects, and the use of relatively inexpensive laser sources. Such characteristics and the fact that BR films can be produced at a low cost makes the system simple to implement, relatively inexpensive and extremely robust. The effects of varying the illuminating area beyond the phase object area and filter saturation are also analyzed.

  5. Accelerating free breathing myocardial perfusion MRI using multi coil radial k - t SLR

    NASA Astrophysics Data System (ADS)

    Goud Lingala, Sajan; DiBella, Edward; Adluru, Ganesh; McGann, Christopher; Jacob, Mathews

    2013-10-01

    The clinical utility of myocardial perfusion MR imaging (MPI) is often restricted by the inability of current acquisition schemes to simultaneously achieve high spatio-temporal resolution, good volume coverage, and high signal to noise ratio. Moreover, many subjects often find it difficult to hold their breath for sufficiently long durations making it difficult to obtain reliable MPI data. Accelerated acquisition of free breathing MPI data can overcome some of these challenges. Recently, an algorithm termed as k - t SLR has been proposed to accelerate dynamic MRI by exploiting sparsity and low rank properties of dynamic MRI data. The main focus of this paper is to further improve k - t SLR and demonstrate its utility in considerably accelerating free breathing MPI. We extend its previous implementation to account for multi-coil radial MPI acquisitions. We perform k - t sampling experiments to compare different radial trajectories and determine the best sampling pattern. We also introduce a novel augmented Lagrangian framework to considerably improve the algorithm’s convergence rate. The proposed algorithm is validated using free breathing rest and stress radial perfusion data sets from two normal subjects and one patient with ischemia. k - t SLR was observed to provide faithful reconstructions at high acceleration levels with minimal artifacts compared to existing MPI acceleration schemes such as spatio-temporal constrained reconstruction and k - t SPARSE/SENSE.

  6. Phase Contrast Wavefront Sensing for Adaptive Optics

    NASA Technical Reports Server (NTRS)

    Bloemhof, E. E.; Wallace, J. K.; Bloemhof, E. E.

    2004-01-01

    Most ground-based adaptive optics systems use one of a small number of wavefront sensor technologies, notably (for relatively high-order systems) the Shack-Hartmann sensor, which provides local measurements of the phase slope (first-derivative) at a number of regularly-spaced points across the telescope pupil. The curvature sensor, with response proportional to the second derivative of the phase, is also sometimes used, but has undesirable noise propagation properties during wavefront reconstruction as the number of actuators becomes large. It is interesting to consider the use for astronomical adaptive optics of the "phase contrast" technique, originally developed for microscopy by Zemike to allow convenient viewing of phase objects. In this technique, the wavefront sensor provides a direct measurement of the local value of phase in each sub-aperture of the pupil. This approach has some obvious disadvantages compared to Shack-Hartmann wavefront sensing, but has some less obvious but substantial advantages as well. Here we evaluate the relative merits in a practical ground-based adaptive optics system.

  7. Monitoring stem cells in phase contrast imaging

    NASA Astrophysics Data System (ADS)

    Lam, K. P.; Dempsey, K. P.; Collins, D. J.; Richardson, J. B.

    2016-04-01

    Understanding the mechanisms behind the proliferation of Mesenchymal Stem cells (MSCs) can offer a greater insight into the behaviour of these cells throughout their life cycles. Traditional methods of determining the rate of MSC differentiation rely on population based studies over an extended time period. However, such methods can be inadequate as they are unable to track cells as they interact; for example, in autologous cell therapies for osteoarthritis, the development of biological assays that could predict in vivo functional activity and biological action are particularly challenging. Here further research is required to determine non-histochemical biomarkers which provide correlations between cell survival and predictive functional outcome. This paper proposes using a (previously developed) advanced texture-based analysis algorithm to facilitate in vitro cells tracking using time-lapsed microscopy. The technique was adopted to monitor stem cells in the context of unlabelled, phase contrast imaging, with the goal of examining the cell to cell interactions in both monoculture and co-culture systems. The results obtained are analysed using established exploratory procedures developed for time series data and compared with the typical fluorescent-based approach of cell labelling. A review of the progress and the lessons learned are also presented.

  8. Quantitative phase-contrast confocal microscope

    PubMed Central

    Liu, Changgeng; Marchesini, Stefano; Kim, Myung K.

    2014-01-01

    We present a quantitative phase-contrast confocal microscope (QPCCM) by combining a line-scanning confocal system with digital holography (DH). This combination can merge the merits of these two different imaging modalities. High-contrast intensity images with low coherent noise, and the optical sectioning capability are made available due to the confocality. Phase profiles of the samples become accessible thanks to DH. QPCCM is able to quantitatively measure the phase variations of optical sections of the opaque samples and has the potential to take high-quality intensity and phase images of non-opaque samples such as many biological samples. Because each line scan is recorded by a hologram that may contain the optical aberrations of the system, it opens avenues for a variety of numerical aberration compensation methods and development of full digital adaptive optics confocal system to emulate current hardware-based adaptive optics system for biomedical imaging, especially ophthalmic imaging. Preliminary experiments with a microscope objective of NA 0.65 and 40 × on opaque samples are presented to demonstrate this idea. The measured lateral and axial resolutions of the intensity images from the current system are ~0.64μm and ~2.70μm respectively. The noise level of the phase profile by QPCCM is ~2.4nm which is better than the result by DH. PMID:25089404

  9. Fourier-based linear systems description of free-breathing pulmonary magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Capaldi, D. P. I.; Svenningsen, S.; Cunningham, I. A.; Parraga, G.

    2015-03-01

    Fourier-decomposition of free-breathing pulmonary magnetic resonance imaging (FDMRI) was recently piloted as a way to provide rapid quantitative pulmonary maps of ventilation and perfusion without the use of exogenous contrast agents. This method exploits fast pulmonary MRI acquisition of free-breathing proton (1H) pulmonary images and non-rigid registration to compensate for changes in position and shape of the thorax associated with breathing. In this way, ventilation imaging using conventional MRI systems can be undertaken but there has been no systematic evaluation of fundamental image quality measurements based on linear systems theory. We investigated the performance of free-breathing pulmonary ventilation imaging using a Fourier-based linear system description of each operation required to generate FDMRI ventilation maps. Twelve subjects with chronic obstructive pulmonary disease (COPD) or bronchiectasis underwent pulmonary function tests and MRI. Non-rigid registration was used to co-register the temporal series of pulmonary images. Pulmonary voxel intensities were aligned along a time axis and discrete Fourier transforms were performed on the periodic signal intensity pattern to generate frequency spectra. We determined the signal-to-noise ratio (SNR) of the FDMRI ventilation maps using a conventional approach (SNRC) and using the Fourier-based description (SNRF). Mean SNR was 4.7 ± 1.3 for subjects with bronchiectasis and 3.4 ± 1.8, for COPD subjects (p>.05). SNRF was significantly different than SNRC (p<.01). SNRF was approximately 50% of SNRC suggesting that the linear system model well-estimates the current approach.

  10. Influence of image registration on ADC images computed from free-breathing diffusion MRIs of the abdomen

    NASA Astrophysics Data System (ADS)

    Guyader, Jean-Marie; Bernardin, Livia; Douglas, Naomi H. M.; Poot, Dirk H. J.; Niessen, Wiro J.; Klein, Stefan

    2014-03-01

    The apparent diffusion coefficient (ADC) is an imaging biomarker providing quantitative information on the diffusion of water in biological tissues. This measurement could be of relevance in oncology drug development, but it suffers from a lack of reliability. ADC images are computed by applying a voxelwise exponential fitting to multiple diffusion-weighted MR images (DW-MRIs) acquired with different diffusion gradients. In the abdomen, respiratory motion induces misalignments in the datasets, creating visible artefacts and inducing errors in the ADC maps. We propose a multistep post-acquisition motion compensation pipeline based on 3D non-rigid registrations. It corrects for motion within each image and brings all DW-MRIs to a common image space. The method is evaluated on 10 datasets of free-breathing abdominal DW-MRIs acquired from healthy volunteers. Regions of interest (ROIs) are segmented in the right part of the abdomen and measurements are compared in the three following cases: no image processing, Gaussian blurring of the raw DW-MRIs and registration. Results show that both blurring and registration improve the visual quality of ADC images, but compared to blurring, registration yields visually sharper images. Measurement uncertainty is reduced both by registration and blurring. For homogeneous ROIs, blurring and registration result in similar median ADCs, which are lower than without processing. In a ROI at the interface between liver and kidney, registration and blurring yield different median ADCs, suggesting that uncorrected motion introduces a bias. Our work indicates that averaging procedures on the scanner should be avoided, as they remove the opportunity to perform motion correction.

  11. Optimization of Coronary Whole-Heart MRA Free Breathing Technique at 3T

    PubMed Central

    Gharib, Ahmed M.; Abd-Elmoniem, Khaled Z.; Herzka, Daniel A.; Ho, Vincent B.; Locklin, Julie; Tzatha, Efstathia; Stuber, Matthias; Pettigrew, Roderic I

    2011-01-01

    Four different techniques for 3T whole-heart coronary MRA using free-breathing 3D segmented parallel imaging and adiabatic T2-Prep were assessed. Coronary MRA at 3T is improved by shortening the acquisition window more than employing the highest spatial resolution. Double oblique whole-heart acquisitions result in better overall image quality and allow for better delineation of the LAD. It is possible to attain shorter acquisition windows and a smaller voxel size at 3T than previously reported at 1.5T. PMID:21871751

  12. Whole left ventricular functional assessment from two minutes free breathing multi-slice CINE acquisition

    NASA Astrophysics Data System (ADS)

    Usman, M.; Atkinson, D.; Heathfield, E.; Greil, G.; Schaeffter, T.; Prieto, C.

    2015-04-01

    Two major challenges in cardiovascular MRI are long scan times due to slow MR acquisition and motion artefacts due to respiratory motion. Recently, a Motion Corrected-Compressed Sensing (MC-CS) technique has been proposed for free breathing 2D dynamic cardiac MRI that addresses these challenges by simultaneously accelerating MR acquisition and correcting for any arbitrary motion in a compressed sensing reconstruction. In this work, the MC-CS framework is combined with parallel imaging for further acceleration, and is termed Motion Corrected Sparse SENSE (MC-SS). Validation of the MC-SS framework is demonstrated in eight volunteers and three patients for left ventricular functional assessment and results are compared with the breath-hold acquisitions as reference. A non-significant difference (P > 0.05) was observed in the volumetric functional measurements (end diastolic volume, end systolic volume, ejection fraction) and myocardial border sharpness values obtained with the proposed and gold standard methods. The proposed method achieves whole heart multi-slice coverage in 2 min under free breathing acquisition eliminating the time needed between breath-holds for instructions and recovery. This results in two-fold speed up of the total acquisition time in comparison to the breath-hold acquisition.

  13. Prospective respiratory-gated micro-CT of free breathing rodents.

    PubMed

    Ford, Nancy L; Nikolov, Hristo N; Norley, Chris J D; Thornton, Michael M; Foster, Paula J; Drangova, Maria; Holdsworth, David W

    2005-09-01

    Microcomputed tomography (Micro-CT) has the potential to noninvasively image the structure of organs in rodent models with high spatial resolution and relatively short image acquisition times. However, motion artifacts associated with the normal respiratory motion of the animal may arise when imaging the abdomen or thorax. To reduce these artifacts and the accompanying loss of spatial resolution, we propose a prospective respiratory gating technique for use with anaesthetized, free-breathing rodents. A custom-made bed with an embedded pressure chamber was connected to a pressure transducer. Anaesthetized animals were placed in the prone position on the bed with their abdomens located over the chamber. During inspiration, the motion of the diaphragm caused an increase in the chamber pressure, which was converted into a voltage signal by the transducer. An output voltage was used to trigger image acquisition at any desired time point in the respiratory cycle. Digital radiographic images were acquired of anaesthetized, free-breathing rats with a digital radiographic system to correlate the respiratory wave form with respiration-induced organ motion. The respiratory wave form was monitored and recorded simultaneously with the x-ray radiation pulses, and an imaging window was defined, beginning at end expiration. Phantom experiments were performed to verify that the respiratory gating apparatus was triggering the micro-CT system. Attached to the distensible phantom were 100 microm diameter copper wires and the measured full width at half maximum was used to assess differences in image quality between respiratory-gated and ungated imaging protocols. This experiment allowed us to quantify the improvement in the spatial resolution, and the reduction of motion artifacts caused by moving structures, in the images resulting from respiratory-gated image acquisitions. The measured wire diameters were 0.135 mm for the stationary phantom image, 0.137 mm for the image gated at end

  14. Acoustic radiation pressure: A 'phase contrast' agent for x-ray phase contrast imaging

    SciTech Connect

    Bailat, Claude J.; Hamilton, Theron J.; Rose-Petruck, Christoph; Diebold, Gerald J.

    2004-11-08

    We show that the radiation pressure exerted by a beam of ultrasound can be used for contrast enhancement in high-resolution x-ray imaging of tissue and soft materials. Interfacial features of objects are highlighted as a result of both the displacement introduced by the ultrasound and the inherent sensitivity of x-ray phase contrast imaging to density variations. The potential of the method is demonstrated by imaging microscopic tumor phantoms embedded into tissue with a thickness typically presented in mammography. The detection limit of micrometer size masses exceeds the resolution of currently available mammography imaging systems. The directionality of the acoustic radiation force and its localization in space permits the imaging of ultrasound-selected tissue volumes. The results presented here suggest that the method may permit the detection of tumors in soft tissue in their early stage of development.

  15. Adaptive optimisation of a generalised phase contrast beam shaping system

    NASA Astrophysics Data System (ADS)

    Kenny, F.; Choi, F. S.; Glückstad, J.; Booth, M. J.

    2015-05-01

    The generalised phase contrast (GPC) method provides versatile and efficient light shaping for a range of applications. We have implemented a generalised phase contrast system that used two passes on a single spatial light modulator (SLM). Both the pupil phase distribution and the phase contrast filter were generated by the SLM. This provided extra flexibility and control over the parameters of the system including the phase step magnitude, shape, radius and position of the filter. A feedback method for the on-line optimisation of these properties was also developed. Using feedback from images of the generated light field, it was possible to dynamically adjust the phase filter parameters to provide optimum contrast.

  16. A semi-automatic method for peak and valley detection in free-breathing respiratory waveforms

    SciTech Connect

    Lu Wei; Nystrom, Michelle M.; Parikh, Parag J.; Fooshee, David R.; Hubenschmidt, James P.; Bradley, Jeffrey D.; Low, Daniel A.

    2006-10-15

    The existing commercial software often inadequately determines respiratory peaks for patients in respiration correlated computed tomography. A semi-automatic method was developed for peak and valley detection in free-breathing respiratory waveforms. First the waveform is separated into breath cycles by identifying intercepts of a moving average curve with the inspiration and expiration branches of the waveform. Peaks and valleys were then defined, respectively, as the maximum and minimum between pairs of alternating inspiration and expiration intercepts. Finally, automatic corrections and manual user interventions were employed. On average for each of the 20 patients, 99% of 307 peaks and valleys were automatically detected in 2.8 s. This method was robust for bellows waveforms with large variations.

  17. Phase contrast image guidance for synchrotron microbeam radiotherapy

    NASA Astrophysics Data System (ADS)

    Pelliccia, Daniele; Crosbie, Jeffrey C.; Larkin, Kieran G.

    2016-08-01

    Recent image guidance developments for preclinical synchrotron microbeam radiotherapy represent a necessary step for future clinical translation of the technique. Image quality can be further improved using x-ray phase contrast, which is readily available at synchrotron facilities. We here describe a methodology for phase contrast image guidance at the Imaging and Medical Beamline at the Australian Synchrotron. Differential phase contrast is measured alongside conventional attenuation and used to improve the image quality. Post-processing based on the inverse Riesz transform is employed on the measured data to obtain noticeably sharper images. The procedure is extremely well suited for applications such as image guidance which require both visual assessment and sample alignment based on semi automatic image registration. Moreover, our approach can be combined with all other differential phase contrast imaging techniques, in all cases where a quantitative evaluation of the refractive index is not required.

  18. Phase contrast image guidance for synchrotron microbeam radiotherapy.

    PubMed

    Pelliccia, Daniele; Crosbie, Jeffrey C; Larkin, Kieran G

    2016-08-21

    Recent image guidance developments for preclinical synchrotron microbeam radiotherapy represent a necessary step for future clinical translation of the technique. Image quality can be further improved using x-ray phase contrast, which is readily available at synchrotron facilities. We here describe a methodology for phase contrast image guidance at the Imaging and Medical Beamline at the Australian Synchrotron. Differential phase contrast is measured alongside conventional attenuation and used to improve the image quality. Post-processing based on the inverse Riesz transform is employed on the measured data to obtain noticeably sharper images. The procedure is extremely well suited for applications such as image guidance which require both visual assessment and sample alignment based on semi automatic image registration. Moreover, our approach can be combined with all other differential phase contrast imaging techniques, in all cases where a quantitative evaluation of the refractive index is not required. PMID:27436750

  19. Helical x-ray differential phase contrast computed tomography

    NASA Astrophysics Data System (ADS)

    Qi, Zhihua; Thériault-Lauzier, Pascal; Bevins, Nicholas; Zambelli, Joseph; Li, Ke; Chen, Guang-Hong

    2011-03-01

    Helical computed tomography revolutionized the field of x-ray computed tomography two decades ago. The simultaneous translation of an image object with a standard computed tomography acquisition allows for fast volumetric scan for long image objects. X-ray phase sensitive imaging methods have been studied over the past few decades to provide new contrast mechanisms for imaging an object. A Talbot-Lau grating interferometer based differential phase contrast imaging method has recently demonstrated its potential for implementation in clinical and industrial applications. In this work, the principles of helical computed tomography are extended to differential phase contrast imaging to produce volumetric reconstructions based on fan-beam data. The method demonstrates the potential for helical differential phase contrast CT to scan long objects with relatively small detector coverage in the axial direction.

  20. Resolution enhancement phase-contrast imaging by microsphere digital holography

    NASA Astrophysics Data System (ADS)

    Wang, Yunxin; Guo, Sha; Wang, Dayong; Lin, Qiaowen; Rong, Lu; Zhao, Jie

    2016-05-01

    Microsphere has shown the superiority of super-resolution imaging in the traditional 2D intensity microscope. Here a microsphere digital holography approach is presented to realize the resolution enhancement phase-contrast imaging. The system is designed by combining the microsphere with the image-plane digital holography. A microsphere very close to the object can increase the resolution by transforming the object wave from the higher frequency to the lower one. The resolution enhancement amplitude and phase images can be retrieved from a single hologram. The experiments are carried on the 1D and 2D gratings, and the results demonstrate that the observed resolution has been improved, meanwhile, the phase-contrast image is obtained. The proposed method can improve the transverse resolution in all directions based on a single exposure. Furthermore, this system has extended the application of the microsphere from the conventional 2D microscopic imaging to 3D phase-contrast microscopic imaging.

  1. Adaptive optimisation of a generalised phase contrast beam shaping system

    PubMed Central

    Kenny, F.; Choi, F.S.; Glückstad, J.; Booth, M.J.

    2015-01-01

    The generalised phase contrast (GPC) method provides versatile and efficient light shaping for a range of applications. We have implemented a generalised phase contrast system that used two passes on a single spatial light modulator (SLM). Both the pupil phase distribution and the phase contrast filter were generated by the SLM. This provided extra flexibility and control over the parameters of the system including the phase step magnitude, shape, radius and position of the filter. A feedback method for the on-line optimisation of these properties was also developed. Using feedback from images of the generated light field, it was possible to dynamically adjust the phase filter parameters to provide optimum contrast. PMID:26089573

  2. Phase-contrast x-ray tomography using synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Bonse, Ulrich; Beckmann, Felix; Bartscher, Markus; Biermann, Theodor; Busch, Frank; Guennewig, Olaf

    1997-10-01

    The principle and experimental l realization of x-ray phase- contrast in compute assisted microtomography ((mu) CT) at the micrometer resolution level is described. The camera used is a modification of a setup previously developed by us for attenuation-contrast (mu) CT using synchrotron x-rays. Phase detection is accomplished by employing the x-ray interferometer. By using x-ray phase contrast it is possible to image structural details in low-z biological tissues much better than with absorption contrast. The advantage of phase over attenuation contrast is not limited to light element or to low x-ray energies. Examples of applying phase contrast (mu) CT to the structural investigation of rat trigeminal nerve are given.

  3. Simultaneous de-noising in phase contrast tomography

    NASA Astrophysics Data System (ADS)

    Koehler, Thomas; Roessl, Ewald

    2012-07-01

    In this work, we investigate methods for de-noising of tomographic differential phase contrast and absorption contrast images. We exploit the fact that in grating-based differential phase contrast imaging (DPCI), first, several images are acquired simultaneously in exactly the same geometry, and second, these different images can show very different contrast-to-noise-ratios. These features of grating-based DPCI are used to generalize the conventional bilateral filter. Experiments using simulations show a superior de-noising performance of the generalized algorithm compared with the conventional one.

  4. Joint image reconstruction and motion parameter estimation for free-breathing navigator-gated cardiac MRI

    NASA Astrophysics Data System (ADS)

    Akçakaya, Mehmet; Basha, Tamer A.; Weingärtner, Sebastian; Nezafat, Reza

    2013-09-01

    We propose an acquisition and reconstruction technique for accelerated free-breathing cardiac MRI acquisitions. For the acquisition, a random undersampling pattern, including a fully-sampled center of k-space, is generated prospectively. The k-space lines specified by this undersampling pattern is acquired with respiratory navigating (NAV), where only the central k-space lines are acquired within the prespecified gating window. For the outer k-space lines, if the NAV signal corresponding to a k-space segment is outside the gating window, the segment is rejected, but not re-acquired. The reconstruction approach jointly estimates the underlying image using a compressed-sensing based approach, and the translational motion parameters for each segment for the outer k-space segments acquired outside the gating window. The feasibility of the approach is demonstrated in healthy adult subjects using whole-heart coronary MRI with a 3-fold accelerated random undersampling pattern. The proposed acquisition and reconstruction technique is compared to parallel imaging with uniform undersampling with 3-fold undersampling. The two techniques exhibit similar image quality with a shorter acquisition time for the proposed approach (4:25+/-0:31 minutes versus 6:52+/-0:19).

  5. Respiratory motion compensation algorithm of ultrasound hepatic perfusion data acquired in free-breathing

    NASA Astrophysics Data System (ADS)

    Wu, Kaizhi; Zhang, Xuming; Chen, Guangxie; Weng, Fei; Ding, Mingyue

    2013-10-01

    Images acquired in free breathing using contrast enhanced ultrasound exhibit a periodic motion that needs to be compensated for if a further accurate quantification of the hepatic perfusion analysis is to be executed. In this work, we present an algorithm to compensate the respiratory motion by effectively combining the PCA (Principal Component Analysis) method and block matching method. The respiratory kinetics of the ultrasound hepatic perfusion image sequences was firstly extracted using the PCA method. Then, the optimal phase of the obtained respiratory kinetics was detected after normalizing the motion amplitude and determining the image subsequences of the original image sequences. The image subsequences were registered by the block matching method using cross-correlation as the similarity. Finally, the motion-compensated contrast images can be acquired by using the position mapping and the algorithm was evaluated by comparing the TICs extracted from the original image sequences and compensated image subsequences. Quantitative comparisons demonstrated that the average fitting error estimated of ROIs (region of interest) was reduced from 10.9278 +/- 6.2756 to 5.1644 +/- 3.3431 after compensating.

  6. Differential phase contrast X-ray imaging system and components

    DOEpatents

    Stutman, Daniel; Finkenthal, Michael

    2014-07-01

    A differential phase contrast X-ray imaging system includes an X-ray illumination system, a beam splitter arranged in an optical path of the X-ray illumination system, and a detection system arranged in an optical path to detect X-rays after passing through the beam splitter.

  7. Phase contrast imaging with coherent high energy X-rays

    SciTech Connect

    Snigireva, I.

    1997-02-01

    X-ray imaging concern high energy domain (>6 keV) like a contact radiography, projection microscopy and tomography is used for many years to discern the features of the internal structure non destructively in material science, medicine and biology. In so doing the main contrast formation is absorption that makes some limitations for imaging of the light density materials and what is more the resolution of these techniques is not better than 10-100 {mu}m. It was turned out that there is now way in which to overcome 1{mu}m or even sub-{mu}m resolution limit except phase contrast imaging. It is well known in optics that the phase contrast is realised when interference between reference wave front and transmitted through the sample take place. Examples of this imaging are: phase contrast microscopy suggested by Zernike and Gabor (in-line) holography. Both of this techniques: phase contrast x-ray microscopy and holography are successfully progressing now in soft x-ray region. For imaging in the hard X-rays to enhance the contrast and to be able to resolve phase variations across the beam the high degree of the time and more importantly spatial coherence is needed. Because of this it was reasonable that the perfect crystal optics was involved like Bonse-Hart interferometry, double-crystal and even triple-crystal set-up using Laue and Bragg geometry with asymmetrically cut crystals.

  8. Optimization of a retrospective technique for respiratory-gated high speed micro-CT of free-breathing rodents

    NASA Astrophysics Data System (ADS)

    Ford, Nancy L.; Wheatley, Andrew R.; Holdsworth, David W.; Drangova, Maria

    2007-09-01

    The objective of this study was to develop a technique for dynamic respiratory imaging using retrospectively gated high-speed micro-CT imaging of free-breathing mice. Free-breathing C57Bl6 mice were scanned using a dynamic micro-CT scanner, comprising a flat-panel detector mounted on a slip-ring gantry. Projection images were acquired over ten complete gantry rotations in 50 s, while monitoring the respiratory motion in synchrony with projection-image acquisition. Projection images belonging to a selected respiratory phase were retrospectively identified and used for 3D reconstruction. The effect of using fewer gantry rotations—which influences both image quality and the ability to quantify respiratory function—was evaluated. Images reconstructed using unique projections from six or more gantry rotations produced acceptable images for quantitative analysis of lung volume, CT density, functional residual capacity and tidal volume. The functional residual capacity (0.15 ± 0.03 mL) and tidal volumes (0.08 ± 0.03 mL) measured in this study agree with previously reported measurements made using prospectively gated micro-CT and at higher resolution (150 µm versus 90 µm voxel spacing). Retrospectively gated micro-CT imaging of free-breathing mice enables quantitative dynamic measurement of morphological and functional parameters in the mouse models of respiratory disease, with scan times as short as 30 s, based on the acquisition of projection images over six gantry rotations.

  9. Graph-based retrospective 4D image construction from free-breathing MRI slice acquisitions

    NASA Astrophysics Data System (ADS)

    Tong, Yubing; Udupa, Jayaram K.; Ciesielski, Krzysztof C.; McDonough, Joseph M.; Mong, Andrew; Campbell, Robert M.

    2014-03-01

    4D or dynamic imaging of the thorax has many potential applications [1, 2]. CT and MRI offer sufficient speed to acquire motion information via 4D imaging. However they have different constraints and requirements. For both modalities both prospective and retrospective respiratory gating and tracking techniques have been developed [3, 4]. For pediatric imaging, x-ray radiation becomes a primary concern and MRI remains as the de facto choice. The pediatric subjects we deal with often suffer from extreme malformations of their chest wall, diaphragm, and/or spine, as such patient cooperation needed by some of the gating and tracking techniques are difficult to realize without causing patient discomfort. Moreover, we are interested in the mechanical function of their thorax in its natural form in tidal breathing. Therefore free-breathing MRI acquisition is the ideal modality of imaging for these patients. In our set up, for each coronal (or sagittal) slice position, slice images are acquired at a rate of about 200-300 ms/slice over several natural breathing cycles. This produces typically several thousands of slices which contain both the anatomic and dynamic information. However, it is not trivial to form a consistent and well defined 4D volume from these data. In this paper, we present a novel graph-based combinatorial optimization solution for constructing the best possible 4D scene from such data entirely in the digital domain. Our proposed method is purely image-based and does not need breath holding or any external surrogates or instruments to record respiratory motion or tidal volume. Both adult and children patients' data are used to illustrate the performance of the proposed method. Experimental results show that the reconstructed 4D scenes are smooth and consistent spatially and temporally, agreeing with known shape and motion of the lungs.

  10. Interactive cell segmentation based on phase contrast optics.

    PubMed

    Su, Hang; Su, Zhou; Zheng, Shibao; Yang, Hua; Wei, Sha

    2014-01-01

    Cell segmentation in phase contrast microscopy images lays a crucial foundation for numerous subsequent computer-aided cell image analysis, but it encounters many unsolved challenges due to image qualities and artifacts caused by phase contrast optics. Addressing the unsolved challenges, the authors propose an interactive cell segmentation scheme over phase retardation features. After partitioning the images into phase homogeneous atoms, human annotations are propagated to unlabeled atoms over an affinity graph that is learned based on discrimination analysis. Then, an active query strategy is proposed for which the most informative unlabeled atom is selected for annotation, which is also propagated to the other unlabeled atoms. Cell segmentation converges to quality results after several rounds of interactions involving both the user's intentions and characteristics of image features. Experimental results demonstrate that cells with different optical properties are well segmented via the proposed approach. PMID:24211879

  11. Helical differential X-ray phase-contrast computed tomography.

    PubMed

    Fu, Jian; Willner, Marian; Chen, Liyuan; Tan, Renbo; Achterhold, Klaus; Bech, Martin; Herzen, Julia; Kunka, Danays; Mohr, Juergen; Pfeiffer, Franz

    2014-05-01

    We report on the first experimental results of helical differential phase-contrast computed tomography (helical DPC-CT) with a laboratory X-ray tube source and a Talbot-Lau grating interferometer. The results experimentally verify the feasibility of helical data acquisition and reconstruction in phase-contrast imaging, in analogy to its use in clinical CT systems. This allows fast and continuous volumetric scans for long objects with lengths exceeding the dimension of the detector. Since helical CT revolutionized the field of medical CT several years ago, we anticipate that this method will bring the same significant impact on the future medical and industrial applications of X-ray DPC-CT. PMID:24518822

  12. Nonlinear dynamic phase contrast microscopy for microfluidic and microbiological applications

    NASA Astrophysics Data System (ADS)

    Denz, C.; Holtmann, F.; Woerdemann, M.; Oevermann, M.

    2008-08-01

    In live sciences, the observation and analysis of moving living cells, molecular motors or motion of micro- and nano-objects is a current field of research. At the same time, microfluidic innovations are needed for biological and medical applications on a micro- and nano-scale. Conventional microscopy techniques are reaching considerable limits with respect to these issues. A promising approach for this challenge is nonlinear dynamic phase contrast microscopy. It is an alternative full field approach that allows to detect motion as well as phase changes of living unstained micro-objects in real-time, thereby being marker free, without contact and non destructive, i.e. fully biocompatible. The generality of this system allows it to be combined with several other microscope techniques such as conventional bright field or fluorescence microscopy. In this article we will present the dynamic phase contrast technique and its applications in analysis of micro organismic dynamics, micro flow velocimetry and micro-mixing analysis.

  13. Image fusion algorithm for differential phase contrast imaging

    NASA Astrophysics Data System (ADS)

    Roessl, Ewald; Koehler, Thomas; van Stevendaal, Udo; Martens, Gerhard; Hauser, Nik; Wang, Zhentian; Stampanoni, Marco

    2012-03-01

    Differential phase-contrast imaging in the x-ray domain provides three physically complementary signals:1, 2 the attenuation, the differential phase-contrast, related to the refractive index, and the dark-field signal, strongly influenced by the total amount of radiation scattered into very small angles. In medical applications, it is of the utmost importance to present to the radiologist all clinically relevant information in as compact a way as possible. Hence, the need arises for a method to combine two or more of the above mentioned signals into one image containing all information relevant for diagnosis. We present an image composition algorithm that fuses the attenuation image and the differential phase contrast image into a composite, final image based on the assumption that the real and imaginary part of the complex refractive index of the sample can be related by a constant scaling factor. The merging is performed in such a way that the composite image is characterized by minimal noise-power at each frequency component.

  14. Grid-Based Fourier Transform Phase Contrast Imaging

    NASA Astrophysics Data System (ADS)

    Tahir, Sajjad

    Low contrast in x-ray attenuation imaging between different materials of low electron density is a limitation of traditional x-ray radiography. Phase contrast imaging offers the potential to improve the contrast between such materials, but due to the requirements on the spatial coherence of the x-ray beam, practical implementation of such systems with tabletop (i.e. non-synchrotron) sources has been limited. One recently developed phase imaging technique employs multiple fine-pitched gratings. However, the strict manufacturing tolerances and precise alignment requirements have limited the widespread adoption of grating-based techniques. In this work, we have investigated a technique recently demonstrated by Bennett et al. that utilizes a single grid of much coarser pitch. Our system consisted of a low power 100 microm spot Mo source, a CCD with 22 microm pixel pitch, and either a focused mammography linear grid or a stainless steel woven mesh. Phase is extracted from a single image by windowing and comparing data localized about harmonics of the grid in the Fourier domain. A Matlab code was written to perform the image processing. For the first time, the effects on the diffraction phase contrast and scattering amplitude images of varying grid types and periods, and of varying the window function type used to separate the harmonics, and the window widths, were investigated. Using the wire mesh, derivatives of the phase along two orthogonal directions were obtained and new methods investigated to form improved phase contrast images.

  15. Phase contrast imaging with micro focus x-ray tube

    NASA Astrophysics Data System (ADS)

    Shovkun, V. Y.; Kumakhov, M. A.

    2005-07-01

    Now the phase-contrast (PC) radiography with monochromatic synchmtron radiation sources is very promising for use in non-destructive industrial control, medical and biological X-ray imaging. Unfortunately synchrotron sources are rather expensive for laboratory practice. We are developing a phase-contrast imaging with a micro focus X-ray tube. We performed numerical calculations with Fresnel-Kirchhgoff formalism to obtain values of PC-signals taking into account polychromatic nature of X-ray radiation, a finite size of a source, and a finite resolution of a detector including spectral sensitivity of the detector. We conducted experiments with a micro focus X-ray tube to find absolute values of PC signals for some models of biological tissue and technical materials in presence of scattering X-rays that emerge from the object. By means of simple set of the experimental arrangement it is possible to obtain the phase-contrast image map of the boundaries between regions with the density difference of order ~1 g/cm3. Under experimental conditions the minimal detected PC-signal is found for the plastic fiber 45 tm in diameter. Examples ofthe X-ray PC-images of fishes, images of air bubbles and ribs, slag inclusions in joint weld of Al-Li alloy materials, and images of sapphire microspheres for cellular metallic structures are presented.

  16. Phase contrast image segmentation using a Laue analyser crystal

    NASA Astrophysics Data System (ADS)

    Kitchen, Marcus J.; Paganin, David M.; Uesugi, Kentaro; Allison, Beth J.; Lewis, Robert A.; Hooper, Stuart B.; Pavlov, Konstantin M.

    2011-02-01

    Dual-energy x-ray imaging is a powerful tool enabling two-component samples to be separated into their constituent objects from two-dimensional images. Phase contrast x-ray imaging can render the boundaries between media of differing refractive indices visible, despite them having similar attenuation properties; this is important for imaging biological soft tissues. We have used a Laue analyser crystal and a monochromatic x-ray source to combine the benefits of both techniques. The Laue analyser creates two distinct phase contrast images that can be simultaneously acquired on a high-resolution detector. These images can be combined to separate the effects of x-ray phase, absorption and scattering and, using the known complex refractive indices of the sample, to quantitatively segment its component materials. We have successfully validated this phase contrast image segmentation (PCIS) using a two-component phantom, containing an iodinated contrast agent, and have also separated the lungs and ribcage in images of a mouse thorax. Simultaneous image acquisition has enabled us to perform functional segmentation of the mouse thorax throughout the respiratory cycle during mechanical ventilation.

  17. Systolically gated 3D phase contrast MRA of mesenteric arteries in suspected mesenteric ischemia

    SciTech Connect

    Wasser, M.N.; Schultze Kool, L.J.; Roos, A. de

    1996-03-01

    Our goal was to assess the value of MRA for detecting stenoses in the celiac (CA) and superior mesenteric (SMA) arteries in patients suspected of having chronic mesenteric ischemia, using an optimized systolically gated 3D phase contrast technique. In an initial study in 24 patients who underwent conventional angiography of the abdominal vessels for different clinical indications, a 3D phase contrast MRA technique (3D-PCA) was evaluated and optimized to image the CAs and SMAs. Subsequently, a prospective study was performed to assess the value of systolically gated 3D-PCA in evaluation of the mesenteric arteries in 10 patients with signs and symptoms of chronic mesenteric ischemia. Intraarterial digital subtraction angiography and surgical findings were used as the reference standard. In the initial study, systolic gating appeared to be essential in imaging the SMA on 3D-PCA. In 10 patients suspected of mesenteric ischemia, systolically gated 3D-PCA identified significant proximal disease in the two mesenteric vessels in 4 patients. These patients underwent successful reconstruction of their stenotic vessels. Cardiac-gated MRA may become a useful tool in selection of patients suspected of having mesenteric ischemia who may benefit from surgery. 16 refs., 6 figs., 4 tabs.

  18. Model-based pancreas segmentation in portal venous phase contrast-enhanced CT images.

    PubMed

    Hammon, Matthias; Cavallaro, Alexander; Erdt, Marius; Dankerl, Peter; Kirschner, Matthias; Drechsler, Klaus; Wesarg, Stefan; Uder, Michael; Janka, Rolf

    2013-12-01

    This study aims to automatically detect and segment the pancreas in portal venous phase contrast-enhanced computed tomography (CT) images. The institutional review board of the University of Erlangen-Nuremberg approved this study and waived the need for informed consent. Discriminative learning is used to build a pancreas tissue classifier incorporating spatial relationships between the pancreas and surrounding organs and vessels. Furthermore, discrete cosine and wavelet transforms are used to build texture features to describe local tissue appearance. Classification is used to guide a constrained statistical shape model to fit the data. The algorithm to detect and segment the pancreas was evaluated on 40 consecutive CT data that were acquired in the portal venous contrast agent phase. Manual segmentation of the pancreas was carried out by experienced radiologists and served as reference standard. Threefold cross validation was performed. The algorithm-based detection and segmentation yielded an average surface distance of 1.7 mm and an average overlap of 61.2 % compared with the reference standard. The overall runtime of the system was 20.4 min. The presented novel approach enables automatic pancreas segmentation in portal venous phase contrast-enhanced CT images which are included in almost every clinical routine abdominal CT examination. Reliable pancreatic segmentation is crucial for computer-aided detection systems and an organ-specific decision support. PMID:23471751

  19. Characterization of free breathing patterns with 5D lung motion model

    SciTech Connect

    Zhao Tianyu; Lu Wei; Yang Deshan; Mutic, Sasa; Noel, Camille E.; Parikh, Parag J.; Bradley, Jeffrey D.; Low, Daniel A.

    2009-11-15

    Purpose: To determine the quiet respiration breathing motion model parameters for lung cancer and nonlung cancer patients. Methods: 49 free breathing patient 4DCT image datasets (25 scans, cine mode) were collected with simultaneous quantitative spirometry. A cross-correlation registration technique was employed to track the lung tissue motion between scans. The registration results were applied to a lung motion model: X-vector=X-vector{sub 0}+{alpha}-vector{beta}-vector f, where X-vector is the position of a piece of tissue located at reference position X-vector{sub 0} during a reference breathing phase (zero tidal volume v, zero airflow f). {alpha}-vector is a parameter that characterizes the motion due to air filling (motion as a function of tidal volume v) and {beta}-vector is the parameter that accounts for the motion due to the imbalance of dynamical stress distributions during inspiration and exhalation that causes lung motion hysteresis (motion as a function of airflow f). The parameters {alpha}-vector and {beta}-vector together provide a quantitative characterization of breathing motion that inherently includes the complex hysteresis interplay. The {alpha}-vector and {beta}-vector distributions were examined for each patient to determine overall general patterns and interpatient pattern variations. Results: For 44 patients, the greatest values of |{alpha}-vector| were observed in the inferior and posterior lungs. For the rest of the patients, |{alpha}-vector| reached its maximum in the anterior lung in three patients and the lateral lung in two patients. The hysteresis motion {beta}-vector had greater variability, but for the majority of patients, |{beta}-vector| was largest in the lateral lungs. Conclusions: This is the first report of the three-dimensional breathing motion model parameters for a large cohort of patients. The model has the potential for noninvasively predicting lung motion. The majority of patients exhibited similar |{alpha}-vector| maps

  20. MO-G-18C-05: Real-Time Prediction in Free-Breathing Perfusion MRI

    SciTech Connect

    Song, H; Liu, W; Ruan, D; Jung, S; Gach, M

    2014-06-15

    Purpose: The aim is to minimize frame-wise difference errors caused by respiratory motion and eliminate the need for breath-holds in magnetic resonance imaging (MRI) sequences with long acquisitions and repeat times (TRs). The technique is being applied to perfusion MRI using arterial spin labeling (ASL). Methods: Respiratory motion prediction (RMP) using navigator echoes was implemented in ASL. A least-square method was used to extract the respiratory motion information from the 1D navigator. A generalized artificial neutral network (ANN) with three layers was developed to simultaneously predict 10 time points forward in time and correct for respiratory motion during MRI acquisition. During the training phase, the parameters of the ANN were optimized to minimize the aggregated prediction error based on acquired navigator data. During realtime prediction, the trained ANN was applied to the most recent estimated displacement trajectory to determine in real-time the amount of spatial Results: The respiratory motion information extracted from the least-square method can accurately represent the navigator profiles, with a normalized chi-square value of 0.037±0.015 across the training phase. During the 60-second training phase, the ANN successfully learned the respiratory motion pattern from the navigator training data. During real-time prediction, the ANN received displacement estimates and predicted the motion in the continuum of a 1.0 s prediction window. The ANN prediction was able to provide corrections for different respiratory states (i.e., inhalation/exhalation) during real-time scanning with a mean absolute error of < 1.8 mm. Conclusion: A new technique enabling free-breathing acquisition during MRI is being developed. A generalized ANN development has demonstrated its efficacy in predicting a continuum of motion profile for volumetric imaging based on navigator inputs. Future work will enhance the robustness of ANN and verify its effectiveness with human

  1. Accuracy of Image Guidance Using Free-Breathing Cone-Beam Computed Tomography for Stereotactic Lung Radiotherapy

    PubMed Central

    Kamomae, Takeshi; Monzen, Hajime; Nakayama, Shinichi; Mizote, Rika; Oonishi, Yuuichi; Kaneshige, Soichiro; Sakamoto, Takashi

    2015-01-01

    Movement of the target object during cone-beam computed tomography (CBCT) leads to motion blurring artifacts. The accuracy of manual image matching in image-guided radiotherapy depends on the image quality. We aimed to assess the accuracy of target position localization using free-breathing CBCT during stereotactic lung radiotherapy. The Vero4DRT linear accelerator device was used for the examinations. Reference point discrepancies between the MV X-ray beam and the CBCT system were calculated using a phantom device with a centrally mounted steel ball. The precision of manual image matching between the CBCT and the averaged intensity (AI) images restructured from four-dimensional CT (4DCT) was estimated with a respiratory motion phantom, as determined in evaluations by five independent operators. Reference point discrepancies between the MV X-ray beam and the CBCT image-guidance systems, categorized as left-right (LR), anterior-posterior (AP), and superior-inferior (SI), were 0.33 ± 0.09, 0.16 ± 0.07, and 0.05 ± 0.04 mm, respectively. The LR, AP, and SI values for residual errors from manual image matching were -0.03 ± 0.22, 0.07 ± 0.25, and -0.79 ± 0.68 mm, respectively. The accuracy of target position localization using the Vero4DRT system in our center was 1.07 ± 1.23 mm (2 SD). This study experimentally demonstrated the sufficient level of geometric accuracy using the free-breathing CBCT and the image-guidance system mounted on the Vero4DRT. However, the inter-observer variation and systematic localization error of image matching substantially affected the overall geometric accuracy. Therefore, when using the free-breathing CBCT images, careful consideration of image matching is especially important. PMID:25954809

  2. Reconstruction of 4D-CT data sets acquired during free breathing for the analysis of respiratory motion

    NASA Astrophysics Data System (ADS)

    Ehrhardt, Jan; Werner, Rene; Frenzel, Thorsten; Säring, Dennis; Lu, Wei; Low, Daniel; Handels, Heinz

    2006-03-01

    Respiratory motion is a significant source of error in radiotherapy treatment planning. 4D-CT data sets can be useful to measure the impact of organ motion caused by breathing. But modern CT scanners can only scan a limited region of the body simultaneously and patients have to be scanned in segments consisting of multiple slices. For studying free breathing motion multislice CT scans can be collected simultaneously with digital spirometry over several breathing cycles. The 4D data set is assembled by sorting the free breathing multislice CT scans according to the couch position and the tidal volume. But artifacts can occur because there are no data segments for exactly the same tidal volume and all couch positions. We present an optical flow based method for the reconstruction of 4D-CT data sets from multislice CT scans, which are collected simultaneously with digital spirometry. The optical flow between the scans is estimated by a non-linear registration method. The calculated velocity field is used to reconstruct a 4D-CT data set by interpolating data at user-defined tidal volumes. By this technique, artifacts can be reduced significantly. The reconstructed 4D-CT data sets are used for studying inner organ motion during the respiratory cycle. The procedures described were applied to reconstruct 4D-CT data sets for four tumour patients who have been scanned during free breathing. The reconstructed 4D data sets were used to quantify organ displacements and to visualize the abdominothoracic organ motion.

  3. Various clinical application of phase contrast X-ray

    NASA Astrophysics Data System (ADS)

    Oh, Chilhwan; Park, Sangyong; Ha, Seunghan; Park, Gyuman; Lee, Gunwoo; Lee, Onseok; Je, Jungho

    2008-02-01

    In biomedical application study using phase contrast X-ray, both sample thickness or density and absorption difference are very important factors in aspects of contrast enhancement. We present experimental evidence that synchrotron hard X-ray are suitable for radiological imaging of biological samples down to the cellular level. We investigated the potential of refractive index radiology using un-monochromatized synchrotron hard X-rays for the imaging of cell and tissue in various diseases. Material had been adopted various medical field, such as apoE knockout mouse in cardiologic field, specimen from renal and prostatic carcinoma patient in urology, basal cell epithelioma in dermatology, brain tissue from autosy sample of pakinson's disease, artificially induced artilrtis tissue from rabbits and extracted tooth from patients of crack tooth syndrome. Formalin and paraffin fixed tissue blocks were cut in 3 mm thickness for the X-ray radiographic imaging. From adjacent areas, 4 μm thickness sections were also prepared for hematoxylin-eosin staining. Radiographic images of dissected tissues were obtained using the hard X-rays from the 7B2 beamline of the Pohang Light Source (PLS). The technique used for the study was the phase contrast images were compared with the optical microscopic images of corresponding histological slides. Radiographic images of various diseased tissues showed clear histological details of organelles in normal tissues. Most of cancerous lesions were well differentiated from adjacent normal tissues and detailed histological features of each tumor were clearly identified. Also normal microstructures were identifiable by the phase contrast imaging. Tissue in cancer or other disease showed clearly different findings from those of surrounding normal tissue. For the first time we successfully demonstrated that synchrotron hard X-rays can be used for radiological imaging of relatively thick tissue samples with great histological details.

  4. Magnetic field induced differential neutron phase contrast imaging

    SciTech Connect

    Strobl, M.; Treimer, W.; Walter, P.; Keil, S.; Manke, I.

    2007-12-17

    Besides the attenuation of a neutron beam penetrating an object, induced phase changes have been utilized to provide contrast in neutron and x-ray imaging. In analogy to differential phase contrast imaging of bulk samples, the refraction of neutrons by magnetic fields yields image contrast. Here, it will be reported how double crystal setups can provide quantitative tomographic images of magnetic fields. The use of magnetic air prisms adequate to split the neutron spin states enables a distinction of field induced phase shifts and these introduced by interaction with matter.

  5. Development of a synthetic phase contrast imaging diagnostic

    SciTech Connect

    Rost, J. C.; Lin, L.; Porkolab, M.

    2010-06-15

    A ''synthetic diagnostic'' has been developed to calculate the expected experimental response of phase contrast imaging (PCI), a scattering diagnostic used to measure density fluctuations in laboratory plasmas, to a tokamak discharge modeled with the GYRO nonlinear gyrokinetic code [J. Candy and R. Waltz, J. Comput. Phys. 186, 545 (2003)]. The synthetic PCI includes the spatial response of the experimental diagnostic, primarily implemented as a line integral of plasma density along the beam path, and the minimum and maximum wavenumber response resulting from the detection scheme. The synthetic PCI can be used for comparisons between GYRO and experiment as well as studies of the PCI response.

  6. Phase Contrast X-ray Imaging Signatures for Security Applications

    SciTech Connect

    Miller, Erin A.; White, Timothy A.; McDonald, Benjamin S.; Seifert, Allen

    2013-02-01

    Abstract: Differential phase contrast imaging with a grating interferometer is a promising new radiographic technique providing three distinct contrast mechanisms - absorption, phase, and scatter (or dark field) - using a conventional x-ray tube source. We investigate the signatures available in these three contrast mechanisms with attention towards potential security applications. We find that the scatter mode in particular is sensitive to textured materials, enabling lowered detection limits than absorption for materials such as powders. We investigate the length scales to which our imaging system is sensitive.

  7. Phase contrast and operation regimes in multifrequency atomic force microscopy

    SciTech Connect

    Santos, Sergio

    2014-04-07

    In amplitude modulation atomic force microscopy the attractive and the repulsive force regimes induce phase shifts above and below 90°, respectively. In the more recent multifrequency approach, however, multiple operation regimes have been reported and the theory should be revisited. Here, a theory of phase contrast in multifrequency atomic force microscopy is developed and discussed in terms of energy transfer between modes, energy dissipation and the kinetic energy and energy transfer associated with externally driven harmonics. The single frequency virial that controls the phase shift might undergo transitions in sign while the average force (modal virial) remains positive (negative)

  8. Development of a synthetic phase contrast imaging diagnostic

    NASA Astrophysics Data System (ADS)

    Rost, J. C.; Lin, L.; Porkolab, M.

    2010-06-01

    A "synthetic diagnostic" has been developed to calculate the expected experimental response of phase contrast imaging (PCI), a scattering diagnostic used to measure density fluctuations in laboratory plasmas, to a tokamak discharge modeled with the GYRO nonlinear gyrokinetic code [J. Candy and R. Waltz, J. Comput. Phys. 186, 545 (2003)]. The synthetic PCI includes the spatial response of the experimental diagnostic, primarily implemented as a line integral of plasma density along the beam path, and the minimum and maximum wavenumber response resulting from the detection scheme. The synthetic PCI can be used for comparisons between GYRO and experiment as well as studies of the PCI response.

  9. Optimization of grating-based phase-contrast imaging setup

    NASA Astrophysics Data System (ADS)

    Baturin, Pavlo; Shafer, Mark

    2014-03-01

    Phase contrast imaging (PCI) technology has emerged over the last decade as a novel imaging technique capable of probing phase characteristics of an object as complimentary information to conventional absorption properties. In this work, we identified and provided a rationale for optimization of key parameters that determine the performance of a Talbot-Lau PCI system. The study used the Fresnel wave propagation theory and system geometry to predict optimal grating alignment conditions necessary for producing maximum-phase contrast. The moiré fringe pattern frequency and angular orientation produced in the X-ray detector plane were studied as functions of the gratings' axial rotation. The effect of axial displacement between source-to-phase (L) and phase-to-absorption (d) gratings, on system contrast, was discussed in detail. The L-d regions of highest contrast were identified, and the dependence of contrast on the energy of the X-ray spectrum was also studied. The predictions made in this study were tested experimentally and showed excellent agreement. The results indicated that the PCI system performance is highly sensitive to alignment. The rationale and recommendations made should serve as guidance in design, development, and optimization of Talbot-Lau PCI systems.

  10. Dynamic Studies of Lung Fluid Clearance with Phase Contrast Imaging

    SciTech Connect

    Kitchen, Marcus J.; Williams, Ivan; Irvine, Sarah C.; Morgan, Michael J.; Paganin, David M.; Lewis, Rob A.; Pavlov, Konstantin; Hooper, Stuart B.; Wallace, Megan J.; Siu, Karen K. W.; Yagi, Naoto; Uesugi, Kentaro

    2007-01-19

    Clearance of liquid from the airways at birth is a poorly understood process, partly due to the difficulties of observing and measuring the distribution of air within the lung. Imaging dynamic processes within the lung in vivo with high contrast and spatial resolution is therefore a major challenge. However, phase contrast X-ray imaging is able to exploit inhaled air as a contrast agent, rendering the lungs of small animals visible due to the large changes in the refractive index at air/tissue interfaces. In concert with the high spatial resolution afforded by X-ray imaging systems (<100 {mu}m), propagation-based phase contrast imaging is ideal for studying lung development. To this end we have utilized intense, monochromatic synchrotron radiation, together with a fast readout CCD camera, to study fluid clearance from the lungs of rabbit pups at birth. Local rates of fluid clearance have been measured from the dynamic sequences using a single image phase retrieval algorithm.

  11. Phase-contrast X-ray imaging of breast.

    PubMed

    Keyriläinen, Jani; Bravin, Alberto; Fernández, Manuel; Tenhunen, Mikko; Virkkunen, Pekka; Suortti, Pekka

    2010-10-01

    When an X-ray wave traverses an object, its amplitude and phase change, resulting in attenuation, interference, and refraction, and in phase-contrast X-ray imaging (PCI) these are converted to intensity changes. The relative change of the X-ray phase per unit path length is even orders of magnitude larger than that of the X-ray amplitude, so that the image contrast based on variation of the X-ray phase is potentially much stronger than the contrast based on X-ray amplitude (absorption contrast). An important medical application of PCI methods is soft-tissue imaging, where the absorption contrast is inherently weak. It is shown by in vitro examples that signs of malignant human breast tumor are enhanced in PCI images. Owing to the strong contrast, the radiation dose can be greatly reduced, so that a high-resolution phase-contrast X-ray tomography of the breast is possible with about 1 mGy mean glandular dose. Scattered radiation carries essential information on the atomic and molecular structure of the object, and particularly small-angle X-ray scattering can be used to trace cancer. The imaging methods developed at the synchrotron radiation facilities will become available in the clinical environment with the ongoing development of compact radiation sources, which produce intense X-ray beams of sufficient coherence. Several developments that are under way are described here. PMID:20799921

  12. A phase contrast interferometer on DIII-D

    SciTech Connect

    Coda, S.; Porkolab, M.; Carlstrom, T.N.

    1992-04-01

    A novel imaging diagnostic has recently become operational on the DIII-D tokamak for the study of density fluctuations at the outer edge of the plasma. The phase contrast imaging approach overcomes the limitations of conventional scattering techniques in the spectral range of interest for transport-related phenomena, by allowing detection of long wavelength modes (up to 7.6 cm) with excellent spatial resolution (5 mm) in the radial direction. Additional motivation for the diagnostic is provided by wave-plasma interactions during heating and current drive experiments in the Ion Cyclotron range of frequencies. Density perturbations of 4 {times} 10{sup 7} cm{sup {minus}3} with a 1 MHz bandwidth can be resolved. The diagnostic employs a 7.6 cm diameter CO{sub 2} laser beam launched vertically across the plasma edge. An image of the plasma is then created on a 16-element detector array: the detector signals are directly proportional to the density fluctuations integrated along each chord. Wavelengths and correlation lengths can be inferred from the spatial mapping. The phase contrast method and its application to DIII-D are described and tests and first plasma data are presented.

  13. Dynamic Studies of Lung Fluid Clearance with Phase Contrast Imaging

    NASA Astrophysics Data System (ADS)

    Kitchen, Marcus J.; Lewis, Rob A.; Hooper, Stuart B.; Wallace, Megan J.; Siu, Karen K. W.; Williams, Ivan; Irvine, Sarah C.; Morgan, Michael J.; Paganin, David M.; Pavlov, Konstantin; Yagi, Naoto; Uesugi, Kentaro

    2007-01-01

    Clearance of liquid from the airways at birth is a poorly understood process, partly due to the difficulties of observing and measuring the distribution of air within the lung. Imaging dynamic processes within the lung in vivo with high contrast and spatial resolution is therefore a major challenge. However, phase contrast X-ray imaging is able to exploit inhaled air as a contrast agent, rendering the lungs of small animals visible due to the large changes in the refractive index at air/tissue interfaces. In concert with the high spatial resolution afforded by X-ray imaging systems (<100 μm), propagation-based phase contrast imaging is ideal for studying lung development. To this end we have utilized intense, monochromatic synchrotron radiation, together with a fast readout CCD camera, to study fluid clearance from the lungs of rabbit pups at birth. Local rates of fluid clearance have been measured from the dynamic sequences using a single image phase retrieval algorithm.

  14. Breast cancer detection using phase contrast diffuse optical tomography

    NASA Astrophysics Data System (ADS)

    Liang, Xiaoping; Zhang, Qizhi; Li, Changqing; Grobmyer, Stephen R.; Fajardo, Laurie L.; Jiang, Huabei

    2007-02-01

    In this report, a phase-contrast diffuse optical tomography system, which can measure the refractive indices of human breast masses in vivo, is described. To investigate the utility of phase-contrast diffuse optical tomography (PCDOT) for differentiation of malignant and benign breast masses in humans, and to compare PCDOT with conventional diffuse optical tomography (DOT) for analysis of breast masses in humans. 35 breast masses were imaged in 33 patients (mean age = 51 years; range 22-80 years) using PCDOT. Images characterizing the tissue refractive index, absorption and scattering of breast masses were obtained with a finite element-based reconstruction algorithm. The accuracies of absorption and scattering images were compared with images of refractive index in light of the pathology results. Absorption and scattering images were unable to accurately discriminate benign from malignant lesions. Malignant lesions tended to have decreased refractive index allowing them to discriminate from benign lesions in most cases. The sensitivity, specificity, false positive value, and overall accuracy for refractive index were 81.8%, 70.8%, 29.2%, and 74.3%, respectively. Overall we show that benign and malignant breast masses in humans demonstrate different refractive index and differences in refractive index properties can be used to discriminate benign from malignant masses in patients with high accuracy. This opens up a new avenue for improved breast cancer detection using NIR diffusing light.

  15. Free-breathing radial volumetric interpolated breath-hold examination vs breath-hold cartesian volumetric interpolated breath-hold examination magnetic resonance imaging of the liver at 1.5T

    PubMed Central

    Yedururi, Sireesha; Kang, HyunSeon C; Wei, Wei; Wagner-Bartak, Nicolaus A; Marcal, Leonardo P; Stafford, R Jason; Willis, Brandy J; Szklaruk, Janio

    2016-01-01

    AIM To compare breath-hold cartesian volumetric interpolated breath-hold examination (cVIBE) and free-breathing radial VIBE (rVIBE) and determine whether rVIBE could replace cVIBE in routine liver magnetic resonance imaging (MRI). METHODS In this prospective study, 15 consecutive patients scheduled for routine MRI of the abdomen underwent pre- and post-contrast breath-hold cVIBE imaging (19 s acquisition time) and free-breathing rVIBE imaging (111 s acquisition time) on a 1.5T Siemens scanner. Three radiologists with 2, 4, and 8 years post-fellowship experience in abdominal imaging evaluated all images. The radiologists were blinded to the sequence types, which were presented in a random order for each patient. For each sequence, the radiologists scored the cVIBE and rVIBE images for liver edge sharpness, hepatic vessel clarity, presence of artifacts, lesion conspicuity, fat saturation, and overall image quality using a five-point scale. RESULTS Compared to rVIBE, cVIBE yielded significantly (P < 0.001) higher scores for liver edge sharpness (mean score, 3.87 vs 3.37), hepatic-vessel clarity (3.71 vs 3.18), artifacts (3.74 vs 3.06), lesion conspicuity (3.81 vs 3.2), and overall image quality (3.91 vs 3.24). cVIBE and rVIBE did not significantly differ in quality of fat saturation (4.12 vs 4.03, P = 0.17). The inter-observer variability with respect to differences between rVIBE and cVIBE scores was close to zero compared to random error and inter-patient variation. Quality of rVIBE images was rated as acceptable for all parameters. CONCLUSION rVIBE cannot replace cVIBE in routine liver MRI. At 1.5T, free-breathing rVIBE yields acceptable, although slightly inferior image quality compared to breath-hold cVIBE. PMID:27551341

  16. Phase contrast imaging of buccal mucosa tissues-Feasibility study

    NASA Astrophysics Data System (ADS)

    Fatima, A.; Tripathi, S.; Shripathi, T.; Kulkarni, V. K.; Banda, N. R.; Agrawal, A. K.; Sarkar, P. S.; Kashyap, Y.; Sinha, A.

    2015-06-01

    Phase Contrast Imaging (PCI) technique has been used to interpret physical parameters obtained from the image taken on the normal buccal mucosa tissue extracted from cheek of a patient. The advantages of this method over the conventional imaging techniques are discussed. PCI technique uses the X-ray phase shift at the edges differentiated by very minute density differences and the edge enhanced high contrast images reveal details of soft tissues. The contrast in the images produced is related to changes in the X-ray refractive index of the tissues resulting in higher clarity compared with conventional absorption based X-ray imaging. The results show that this type of imaging has better ability to visualize microstructures of biological soft tissues with good contrast, which can lead to the diagnosis of lesions at an early stage of the diseases.

  17. Neural stem cell tracking with phase contrast video microscopy

    NASA Astrophysics Data System (ADS)

    Rigaud, Stéphane U.; Loménie, Nicolas

    2011-03-01

    Tracking and segmenting objects for video surveillance is a well known field of research and very efficient methods exist. Usually embedded in traffic surveillance camera, these processes are not necessary adapted for biological surveillance context. In stem cell study, the design of a framework to monitor cell development in real time improves the stem cell analysis and biological understanding. In this purpose, we propose to test the Σ - ▵ motion filter, normally developed for security and surveillance camera, in order to track neural stem cells and their evolution over time, based on phase contrast image sequences. The motion filter is based on the difference between the current frame and a reference image of the background and uses a recursive spatio-temporal morphological operator called hybrid reconstruction to compensate for ghost and trace usually occurring with those kinds of methods.

  18. Quantitative Phase Contrast Digital Holographic Microscopy in Biophotonics

    NASA Astrophysics Data System (ADS)

    Kemper, Björn; Langehanenberg, Patrik; von Bally, Gert

    2010-11-01

    Label-free, non-contact, non-destructive, on-line (video repetition rate), high resolution, full field (no scanning), quantitative analysis of morphology and dynamic processes in living cells are required features in life science research and medical diagnostics. Digital Holography combined with microscopic imaging provides these features simultaneously. The modular integration of digital holographic microscopy (DHM) into commercial microscopes yields an axial resolution with interferometric resolution while the lateral resolution is diffraction limited. As amplitude and phase are available by numerical reconstruction from a single digital hologram subsequent automated focus correction is enabled. The evaluation of quantitative digital holographic phase contrast images permits also an effective detection of lateral object movements. Thus, 3D tracking is achieved. The applicability of DHM techniques for dynamic live cell analysis is demonstrated by results from tumor cells and human erythrocytes.

  19. Effect of coherence loss in differential phase contrast imaging

    NASA Astrophysics Data System (ADS)

    Cai, Weixing; Ning, Ruola; Liu, Jiangkun

    2014-03-01

    Coherence property of x-rays is critical in the grating-based differential phase contrast (DPC) imaging because it is the physical foundation that makes any form of phase contrast imaging possible. Loss of coherence is an important experimental issue, which results in increased image noise and reduced object contrast in DPC images and DPC cone beam CT (DPC-CBCT) reconstructions. In this study, experimental results are investigated to characterize the visibility loss (a measurement of coherence loss) in several different applications, including different-sized phantom imaging, specimen imaging and small animal imaging. Key measurements include coherence loss (relative intensity changes in the area of interest in phase-stepping images), contrast and noise level in retrieved DPC images, and contrast and noise level in reconstructed DPC-CBCT images. The influence of size and composition of imaged object (uniform object, bones, skin hairs, tissues, and etc) will be quantified. The same investigation is also applied for moiré pattern-based DPC-CBCT imaging with the same exposure dose. A theoretical model is established to relate coherence loss, noise level in phase stepping images (or moiré images), and the contrast and noise in the retrieved DPC images. Experiment results show that uniform objects lead to a small coherence loss even when the attenuation is higher, while objects with large amount of small structures result in huge coherence loss even when the attenuation is small. The theoretical model predicts the noise level in retrieved DPC images, and it also suggests a minimum dose required for DPC imaging to compensate for coherence loss.

  20. Performance of simultaneous high temporal resolution quantitative perfusion imaging of bladder tumors and conventional multi-phase urography using a novel free-breathing continuously acquired radial compressed-sensing MRI sequence☆,☆☆

    PubMed Central

    Parikh, Nainesh; Ream, Justin M.; Zhang, Hoi Cheung; Block, Kai Tobias; Chandarana, Hersh; Rosenkrantz, Andrew B.

    2016-01-01

    Purpose To investigate the feasibility of high temporal resolution quantitative perfusion imaging of bladder tumors performed simultaneously with conventional multi-phase MR urography (MRU) using a novel free-breathing continuously acquired radial MRI sequence with compressed-sensing reconstruction. Methods: 22 patients with bladder lesions underwent MRU using GRASP (Golden-angle RAdial Sparse Parallel) acquisition. Multi-phase contrast-enhanced abdominopelvic GRASP was performed during free-breathing (1.4 × 1.4 × 3.0 mm3 voxel size; 3:44 min acquisition). Two dynamic datasets were retrospectively reconstructed by combining different numbers of sequentially acquired spokes into each dynamic frame: 110 spokes per frame for 25-s temporal resolution (serving as conventional MRU for clinical interpretation) and 8 spokes per frame for 1.7-s resolution. Using 1.7-s resolution images, ROIs were placed within bladder lesions and normal bladder wall, a femoral artery arterial input function was generated, and the Generalized Kinetic Model was applied. Results Biopsy/cystectomy demonstrated 16 bladder tumors (13 stage ≥ T2, 3 stage ≤ T1) and 6 benign lesions. All lesions were well visualized using 25-s clinical multi-phase images. Using 1.7-s resolution images, Ktrans was significantly higher in tumors (0.38 ± 0.24) than normal bladder (0.12 ± 0.02 = 8, p b 0.001) or benign lesions (0.15 ± 0.04, p = 0.033). Ratio between Ktrans of lesions and normal bladder was nearly double for tumors than benign lesions (4.3 ± 3.4 vs. 2.2 ± 1.6), and Ktrans was nearly double in stage ≥ T2 than stage ≤ T1 tumors (0.44 ± 0.24 vs. 0.24 ± 0.24), although these did not approach significance (p = 0.180–0.209), possibly related to small sample size. Conclusion GRASP allows simultaneous quantitative high temporal resolution perfusion of bladder lesions during clinical MRU examinations using only one contrast injection and without additional scan time. PMID:26740058

  1. High spatial and temporal resolution retrospective cine cardiovascular magnetic resonance from shortened free breathing real-time acquisitions

    PubMed Central

    2013-01-01

    Background Cine cardiovascular magnetic resonance (CMR) is challenging in patients who cannot perform repeated breath holds. Real-time, free-breathing acquisition is an alternative, but image quality is typically inferior. There is a clinical need for techniques that achieve similar image quality to the segmented cine using a free breathing acquisition. Previously, high quality retrospectively gated cine images have been reconstructed from real-time acquisitions using parallel imaging and motion correction. These methods had limited clinical applicability due to lengthy acquisitions and volumetric measurements obtained with such methods have not previously been evaluated systematically. Methods This study introduces a new retrospective reconstruction scheme for real-time cine imaging which aims to shorten the required acquisition. A real-time acquisition of 16-20s per acquired slice was inputted into a retrospective cine reconstruction algorithm, which employed non-rigid registration to remove respiratory motion and SPIRiT non-linear reconstruction with temporal regularization to fill in missing data. The algorithm was used to reconstruct cine loops with high spatial (1.3-1.8 × 1.8-2.1 mm2) and temporal resolution (retrospectively gated, 30 cardiac phases, temporal resolution 34.3 ± 9.1 ms). Validation was performed in 15 healthy volunteers using two different acquisition resolutions (256 × 144/192 × 128 matrix sizes). For each subject, 9 to 12 short axis and 3 long axis slices were imaged with both segmented and real-time acquisitions. The retrospectively reconstructed real-time cine images were compared to a traditional segmented breath-held acquisition in terms of image quality scores. Image quality scoring was performed by two experts using a scale between 1 and 5 (poor to good). For every subject, LAX and three SAX slices were selected and reviewed in the random order. The reviewers were blinded to the reconstruction approach and

  2. Imaging of cardiac perfusion of free-breathing small animals using dynamic phase-correlated micro-CT

    SciTech Connect

    Sawall, Stefan; Kuntz, Jan; Socher, Michaela; Knaup, Michael; Hess, Andreas; Bartling, Soenke; Kachelriess, Marc

    2012-12-15

    Purpose:Mouse models of cardiac diseases have proven to be a valuable tool in preclinical research. The high cardiac and respiratory rates of free breathing mice prohibit conventional in vivo cardiac perfusion studies using computed tomography even if gating methods are applied. This makes a sacrification of the animals unavoidable and only allows for the application of ex vivo methods. Methods: To overcome this issue the authors propose a low dose scan protocol and an associated reconstruction algorithm that allows for in vivo imaging of cardiac perfusion and associated processes that are retrospectively synchronized to the respiratory and cardiac motion of the animal. The scan protocol consists of repetitive injections of contrast media within several consecutive scans while the ECG, respiratory motion, and timestamp of contrast injection are recorded and synchronized to the acquired projections. The iterative reconstruction algorithm employs a six-dimensional edge-preserving filter to provide low-noise, motion artifact-free images of the animal examined using the authors' low dose scan protocol. Results: The reconstructions obtained show that the complete temporal bolus evolution can be visualized and quantified in any desired combination of cardiac and respiratory phase including reperfusion phases. The proposed reconstruction method thereby keeps the administered radiation dose at a minimum and thus reduces metabolic inference to the animal allowing for longitudinal studies. Conclusions: The authors' low dose scan protocol and phase-correlated dynamic reconstruction algorithm allow for an easy and effective way to visualize phase-correlated perfusion processes in routine laboratory studies using free-breathing mice.

  3. Modeling and Analysis of Phase Contrast Imaging Measurements

    NASA Astrophysics Data System (ADS)

    Rost, J. C.; Porkolab, M.; Dorris, J. R.; Candy, J.; Burrell, K. H.

    2007-11-01

    The phase contrast imaging (PCI) diagnostic on DIII-D has been operated in several configurations over its lifetime. The beam path was changed in 2003 from tangential at the midplane LCFS to a path passing through the edge at an angle near 45 degrees and reaching typically r/a=0.8, and the maximum wavenumber has been increased from 7 to 30 cm-1. A synthetic diagnostic (SD) has been created to model all configurations of the PCI by post-processing the output of the GYRO gyrokinetic simulation. The SD includes line integration along the full path and models the detector to obtain the high- and low-k cutoffs. Modeling of a plasma discharge typical of DIII-D is used to interpret the PCI spectra S(k,f) in terms of turbulent ballooning modes and local S(kr,kθ,f). This allows us to identify parts of the PCI spectra with different plasma modes (ITG, TEM, ETG), separate effects of Doppler shift and intrinsic mode velocity in the measurement, and improve comparisons with other diagnostics. The SD will contribute to validation of the model through comparison between simulation and experiment.

  4. Unstained viable cell recognition in phase-contrast microscopy

    NASA Astrophysics Data System (ADS)

    Skoczylas, M.; Rakowski, W.; Cherubini, R.; Gerardi, S.

    2011-09-01

    Individual cell recognition is a relevant task to be accomplished when single-ion microbeam irradiations are performed. At INFN-LNL facility cell visualization system is based on a phase-contrast optical microscope, without the use of any cell dye. Unstained cells are seeded in the special designed Petri dish, between two mylar foils, and at present the cell recognition is achieved manually by an expert operator. Nevertheless, this procedure is time consuming and sometimes it could be not practical if the amount of living cells to be irradiated is large. To reduce the time needed to recognize unstained cells on the Petri dish, it has been designed and implemented an automated, parallel algorithm. Overlapping ROIs sliding in steps over the captured grayscale image are firstly pre-classified and potential cell markers for the segmentation are obtained. Segmented objects are additionally classified to categorize cell bodies from other structures considered as sample dirt or background. As a result, cell coordinates are passed to the dedicated CELLView program that controls all the LNL single-ion microbeam irradiation protocol, including the positioning of individual cells in front of the ion beam. Unstained cell recognition system was successfully tested in experimental conditions with two different mylar surfaces. The recognition time and accuracy was acceptable, however, improvements in speed would be useful.

  5. Adequacy of inhale/exhale breathhold CT based ITV margins and image-guided registration for free-breathing pancreas and liver SBRT

    PubMed Central

    2014-01-01

    Purpose To evaluate use of breath-hold CTs and implanted fiducials for definition of the internal target volume (ITV) margin for upper abdominal stereotactic body radiation therapy (SBRT). To study the statistics of inter- and intra-fractional motion information. Methods and materials 11 patients treated with SBRT for locally advanced pancreatic cancer (LAPC) or liver cancer were included in the study. Patients underwent fiducial implantation, free-breathing CT and breath-hold CTs at end inhalation/exhalation. All patients were planned and treated with SBRT using volumetric modulated arc therapy (VMAT). Two margin strategies were studied: Strategy I uses PTV = ITV + 3 mm; Strategy II uses PTV = GTV + 1.5 cm. Both CBCT and kV orthogonal images were taken and analyzed for setup before patient treatments. Tumor motion statistics based on skeletal registration and on fiducial registration were analyzed by fitting to Gaussian functions. Results All 11 patients met SBRT planning dose constraints using strategy I. Average ITV margins for the 11 patients were 2 mm RL, 6 mm AP, and 6 mm SI. Skeletal registration resulted in high probability (RL = 69%, AP = 4.6%, SI = 39%) that part of the tumor will be outside the ITV. With the 3 mm ITV expansion (Strategy 1), the probability reduced to RL 32%, AP 0.3%, SI 20% for skeletal registration; and RL 1.2%, AP 0%, SI 7% for fiducial registration. All 7 pancreatic patients and 2 liver patients failed to meet SBRT dose constraints using strategy II. The liver dose was increased by 36% for the other 2 liver patients that met the SBRT dose constraints with strategy II. Conclusions Image guidance matching to skeletal anatomy is inadequate for SBRT positioning in the upper abdomen and usage of fiducials is highly recommended. Even with fiducial implantation and definition of an ITV, a minimal 3 mm planning margin around the ITV is needed to accommodate intra-fractional uncertainties. PMID:24401365

  6. Demonstration of synchrotron x-ray phase contrast imaging computed tomography of infiltrative transitional cell carcinoma of the prostatic urethra in a dog.

    PubMed

    Montgomery, James E; Wesolowski, Michal J; Wolkowski, Bailey; Chibbar, Rajni; Snead, Elisabeth C R; Singh, Jaswant; Pettitt, Murray; Malhi, Pritpal S; Barboza, Trinita; Adams, Gregg

    2016-01-01

    Prostatic urethral transitional cell carcinoma with prostatic invasion in a dog was imaged with abdominal radiography and abdominal ultrasonography antemortem. Synchrotron in-line x-ray phase contrast imaging computed tomography (XPCI-CT) was performed on the prostate ex vivo at the Canadian Light Source Synchrotron and compared to histology. XPCI-CT imaging provides greater soft tissue contrast than conventional absorption-based x-ray imaging modalities, permitting visualization of regions of inflammatory cell infiltration, differentiation of invasive versus noninvasive tumor regions, and areas of necrosis and mineralization. This represents the first report of XPCI-CT images of an invasive prostatic urothelial neoplasm in a dog. PMID:27014719

  7. MR phase-contrast imaging in pulmonary hypertension.

    PubMed

    Reiter, Ursula; Reiter, Gert; Fuchsjäger, Michael

    2016-07-01

    Pulmonary hypertension (PH) is a life-threatening, multifactorial pathophysiological haemodynamic condition, diagnosed when the mean pulmonary arterial pressure equals or exceeds 25 mmHg at rest during right heart catheterization. Cardiac MRI, in general, and MR phase-contrast (PC) imaging, in particular, have emerged as potential techniques for the standardized assessment of cardiovascular function, morphology and haemodynamics in PH. Allowing the quantification and characterization of macroscopic cardiovascular blood flow, MR PC imaging offers non-invasive evaluation of haemodynamic alterations associated with PH. Techniques used to study the PH include both the routine two-dimensional (2D) approach measuring predominant velocities through an acquisition plane and the rapidly evolving four-dimensional (4D) PC imaging, which enables the assessment of the complete time-resolved, three-directional blood-flow velocity field in a volume. Numerous parameters such as pulmonary arterial mean velocity, vessel distensibility, flow acceleration time and volume and tricuspid regurgitation peak velocity, as well as the duration and onset of vortical blood flow in the main pulmonary artery, have been explored to either diagnose PH or find non-invasive correlates to right heart catheter parameters. Furthermore, PC imaging-based analysis of pulmonary arterial pulse-wave velocities, wall shear stress and kinetic energy losses grants novel insights into cardiopulmonary remodelling in PH. This review aimed to outline the current applications of 2D and 4D PC imaging in PH and show why this technique has the potential to contribute significantly to early diagnosis and characterization of PH. PMID:26942293

  8. Chemical Shift Induced Phase Errors in Phase Contrast MRI

    PubMed Central

    Middione, Matthew J.; Ennis, Daniel B.

    2012-01-01

    Phase contrast magnetic resonance imaging (PC-MRI) is subject to numerous sources of error, which decrease clinical confidence in the reported measures. This work outlines how stationary perivascular fat can impart a significant chemical shift induced PC-MRI measurement error using computational simulations, in vitro, and in vivo experiments. This chemical shift error does not subtract in phase difference processing, but can be minimized with proper parameter selection. The chemical shift induced phase errors largely depend on both the receiver bandwidth (BW) and the TE. Both theory and an in vivo comparison of the maximum difference in net forward flow between vessels with and without perivascular fat indicated that the effects of chemically shifted perivascular fat are minimized by the use of high BW (814 Hz/px) and an in-phase TE (HBW-TEIN). In healthy volunteers (N=10) HBW-TEIN significantly improves intrapatient net forward flow agreement compared to low BW (401 Hz/px) and a mid-phase TE as indicated by significantly decreased measurement biases and limits of agreement for the ascending aorta (1.8±0.5 mL vs. 6.4±2.8 mL, P=0.01), main pulmonary artery (2.0±0.9 mL vs. 11.9±5.8 mL, P=0.04), the left pulmonary artery (1.3±0.9 mL vs. 5.4±2.5 mL, P=0.003), and all vessels (1.7±0.8 mL vs. 7.2±4.4 mL, P=0.001). PMID:22488490

  9. Quantitative volumetric breast density estimation using phase contrast mammography

    NASA Astrophysics Data System (ADS)

    Wang, Zhentian; Hauser, Nik; Kubik-Huch, Rahel A.; D'Isidoro, Fabio; Stampanoni, Marco

    2015-05-01

    Phase contrast mammography using a grating interferometer is an emerging technology for breast imaging. It provides complementary information to the conventional absorption-based methods. Additional diagnostic values could be further obtained by retrieving quantitative information from the three physical signals (absorption, differential phase and small-angle scattering) yielded simultaneously. We report a non-parametric quantitative volumetric breast density estimation method by exploiting the ratio (dubbed the R value) of the absorption signal to the small-angle scattering signal. The R value is used to determine breast composition and the volumetric breast density (VBD) of the whole breast is obtained analytically by deducing the relationship between the R value and the pixel-wise breast density. The proposed method is tested by a phantom study and a group of 27 mastectomy samples. In the clinical evaluation, the estimated VBD values from both cranio-caudal (CC) and anterior-posterior (AP) views are compared with the ACR scores given by radiologists to the pre-surgical mammograms. The results show that the estimated VBD results using the proposed method are consistent with the pre-surgical ACR scores, indicating the effectiveness of this method in breast density estimation. A positive correlation is found between the estimated VBD and the diagnostic ACR score for both the CC view (p=0.033 ) and AP view (p=0.001 ). A linear regression between the results of the CC view and AP view showed a correlation coefficient γ = 0.77, which indicates the robustness of the proposed method and the quantitative character of the additional information obtained with our approach.

  10. [An Examination of Variable Image Positions in the Aortic Valve Blood Flow Using Phase Contrast MRI: Effect of Breath-holding Methods in Healthy Volunteers].

    PubMed

    Nakagawa, Kenichi; Morimoto, Noriyoshi; Fukushima, Sachi

    2015-12-01

    Phase contrast MRI (PC-MRI) is a useful tool for evaluating valvular pathology. In addition, PC-MRI can provide a noninvasive assessment of blood flow in an arbitrary cross section. However, the blood flow measurement with breath-hold or free breath PC-MRI may be different from each other because of intrathoracic pressure changing and variable image position. The aim of this study was to find both the optimal breath-hold technique and the image position. Quantitative flow images were acquired in four planes (ascending aorta: Ao, sino-tubular junction: STJ, valsalva sinus: valsalva, left ventricular outflow tract: LVOT), in healthy subjects (n=10). The study protocol was divided into two parts: (1) stroke volume (SV) measured in each slice positions by using inspiration, expiration, and navigation method during normal breathing and (2) SV measured at each breath-hold techniques in the Ao, STJ, valsalva, and LVOT. As a result, (1) SV of the respective measurement positions were not significant by using inspiration, expiration, and navigation method and (2) LVOT SV was significantly lower than Ao, STJ, and valsalva. PMID:26685835

  11. Dosimetric impact of motion in free-breathing and gated lung radiotherapy: A 4D Monte Carlo study of intrafraction and interfraction effects

    PubMed Central

    Seco, Joao; Sharp, Greg C.; Wu, Ziji; Gierga, David; Buettner, Florian; Paganetti, Harald

    2008-01-01

    The purpose of this study was to investigate if interfraction and intrafraction motion in free-breathing and gated lung IMRT can lead to systematic dose differences between 3DCT and 4DCT. Dosimetric effects were studied considering the breathing pattern of three patients monitored during the course of their treatment and an in-house developed 4D Monte Carlo framework. Imaging data were taken in free-breathing and in cine mode for both 3D and 4D acquisition. Treatment planning for IMRT delivery was done based on the free-breathing data with the corvus (North American Scientific, Chatsworth, CA) planning system. The dose distributions as a function of phase in the breathing cycle were combined using deformable image registration. The study focused on (a) assessing the accuracy of the corvus pencil beam algorithm with Monte Carlo dose calculation in the lung, (b) evaluating the dosimetric effect of motion on the individual breathing phases of the respiratory cycle, and (c) assessing intrafraction and interfraction motion effects during free-breathing or gated radiotherapy. The comparison between (a) the planning system and the Monte Carlo system shows that the pencil beam algorithm underestimates the dose in low-density regions, such as lung tissue, and overestimates the dose in high-density regions, such as bone, by 5% or more of the prescribed dose (corresponding to approximately 3–5 Gy for the cases considered). For the patients studied this could have a significant impact on the dose volume histograms for the target structures depending on the margin added to the clinical target volume (CTV) to produce either the planning target (PTV) or internal target volume (ITV). The dose differences between (b) phases in the breathing cycle and the free-breathing case were shown to be negligible for all phases except for the inhale phase, where an underdosage of the tumor by as much as 9.3 Gy relative to the free-breathing was observed. The large difference was due to

  12. The lamina splendens of articular cartilage is an artefact of phase contrast microscopy.

    PubMed

    Aspden, R M; Hukins, D W

    1979-11-30

    The so-called lamina splendens of articular cartilage is shown to be a characteristic of phase contrast microscopy; this technique provides no evidence for an anatomically distinct surface layer. Fresnel diffraction occurs at edges separating regions of different refractive indices. These diffraction effects, when viewed under phase contrast, lead to the appearance of a bright line along the edge. PMID:42065

  13. Phase contrast portal imaging for image-guided microbeam radiation therapy

    NASA Astrophysics Data System (ADS)

    Umetani, Keiji; Kondoh, Takeshi

    2014-03-01

    High-dose synchrotron microbeam radiation therapy is a unique treatment technique used to destroy tumors without severely affecting circumjacent healthy tissue. We applied a phase contrast technique to portal imaging in preclinical microbeam radiation therapy experiments. Phase contrast portal imaging is expected to enable us to obtain higherresolution X-ray images at therapeutic X-ray energies compared to conventional portal imaging. Frontal view images of a mouse head sample were acquired in propagation-based phase contrast imaging. The phase contrast images depicted edge-enhanced fine structures of the parietal bones surrounding the cerebrum. The phase contrast technique is expected to be effective in bony-landmark-based verification for image-guided radiation therapy.

  14. Lung Motion Model Validation Experiments, Free-Breathing Tissue Densitometry, and Ventilation Mapping using Fast Helical CT Imaging

    NASA Astrophysics Data System (ADS)

    Dou, Hsiang-Tai

    The uncertainties due to respiratory motion present significant challenges to accurate characterization of cancerous tissues both in terms of imaging and treatment. Currently available clinical lung imaging techniques are subject to inferior image quality and incorrect motion estimation, with consequences that can systematically impact the downstream treatment delivery and outcome. The main objective of this thesis is the development of the techniques of fast helical computed tomography (CT) imaging and deformable image registration for the radiotherapy applications in accurate breathing motion modeling, lung tissue density modeling and ventilation imaging. Fast helical CT scanning was performed on 64-slice CT scanner using the shortest available gantry rotation time and largest pitch value such that scanning of the thorax region amounts to just two seconds, which is less than typical breathing cycle in humans. The scanning was conducted under free breathing condition. Any portion of the lung anatomy undergoing such scanning protocol would be irradiated for only a quarter second, effectively removing any motion induced image artifacts. The resulting CT data were pristine volumetric images that record the lung tissue position and density in a fraction of the breathing cycle. Following our developed protocol, multiple fast helical CT scans were acquired to sample the tissue positions in different breathing states. To measure the tissue displacement, deformable image registration was performed that registers the non-reference images to the reference one. In modeling breathing motion, external breathing surrogate signal was recorded synchronously with the CT image slices. This allowed for the tissue-specific displacement to be modeled as parametrization of the recorded breathing signal using the 5D lung motion model. To assess the accuracy of the motion model in describing tissue position change, the model was used to simulate the original high-pitch helical CT scan

  15. Lung Motion Model Validation Experiments, Free-Breathing Tissue Densitometry, and Ventilation Mapping using Fast Helical CT Imaging

    NASA Astrophysics Data System (ADS)

    Dou, Hsiang-Tai

    The uncertainties due to respiratory motion present significant challenges to accurate characterization of cancerous tissues both in terms of imaging and treatment. Currently available clinical lung imaging techniques are subject to inferior image quality and incorrect motion estimation, with consequences that can systematically impact the downstream treatment delivery and outcome. The main objective of this thesis is the development of the techniques of fast helical computed tomography (CT) imaging and deformable image registration for the radiotherapy applications in accurate breathing motion modeling, lung tissue density modeling and ventilation imaging. Fast helical CT scanning was performed on 64-slice CT scanner using the shortest available gantry rotation time and largest pitch value such that scanning of the thorax region amounts to just two seconds, which is less than typical breathing cycle in humans. The scanning was conducted under free breathing condition. Any portion of the lung anatomy undergoing such scanning protocol would be irradiated for only a quarter second, effectively removing any motion induced image artifacts. The resulting CT data were pristine volumetric images that record the lung tissue position and density in a fraction of the breathing cycle. Following our developed protocol, multiple fast helical CT scans were acquired to sample the tissue positions in different breathing states. To measure the tissue displacement, deformable image registration was performed that registers the non-reference images to the reference one. In modeling breathing motion, external breathing surrogate signal was recorded synchronously with the CT image slices. This allowed for the tissue-specific displacement to be modeled as parametrization of the recorded breathing signal using the 5D lung motion model. To assess the accuracy of the motion model in describing tissue position change, the model was used to simulate the original high-pitch helical CT scan

  16. In-line phase-contrast and grating-based phase-contrast synchrotron imaging study of brain micrometastasis of breast cancer

    NASA Astrophysics Data System (ADS)

    Huang, Sheng; Kou, Binquan; Chi, Yayun; Xi, Yan; Cao, Yixin; Cui, Wenli; Hu, Xin; Shao, Zhimin; Guo, Han; Fu, Yanan; Xiao, Tiqiao; Sun, Jianqi; Zhao, Jun; Wang, Yujie; Wu, Jiong

    2015-03-01

    Current bio-medical imaging researches aim to detect brain micrometastasis in early stage for its increasing incidence and high mortality rates. Synchrotron phase-contrast imaging techniques, such as in-line phase-contrast (IPC) and grating-based phase-contrast (GPC) imaging, could provide a high spatial and density imaging study of biological specimens' 3D structures. In this study, we demonstrated the detection efficiencies of these two imaging tools on breast cancer micrometastasis in an ex vivo mouse brain. We found that both IPC and GPC can differentiate abnormal brain structures induced by micrometastasis from the surrounding normal tissues. We also found that GPC was more sensitive in detecting the small metastasis as compared to IPC.

  17. TH-C-18A-11: Investigating the Minimum Scan Parameters Required to Generate Free-Breathing Fast-Helical CT Scans Without Motion-Artifacts

    SciTech Connect

    Thomas, D; Neylon, J; Dou, T; Jani, S; Lamb, J; Low, D; Tan, J

    2014-06-15

    Purpose: A recently proposed 4D-CT protocol uses deformable registration of free-breathing fast-helical CT scans to generate a breathing motion model. In order to allow accurate registration, free-breathing images are required to be free of doubling-artifacts, which arise when tissue motion is greater than scan speed. This work identifies the minimum scanner parameters required to successfully generate free-breathing fast-helical scans without doubling-artifacts. Methods: 10 patients were imaged under free breathing conditions 25 times in alternating directions with a 64-slice CT scanner using a low dose fast helical protocol. A high temporal resolution (0.1s) 4D-CT was generated using a patient specific motion model and patient breathing waveforms, and used as the input for a scanner simulation. Forward projections were calculated using helical cone-beam geometry (800 projections per rotation) and a GPU accelerated reconstruction algorithm was implemented. Various CT scanner detector widths and rotation times were simulated, and verified using a motion phantom. Doubling-artifacts were quantified in patient images using structural similarity maps to determine the similarity between axial slices. Results: Increasing amounts of doubling-artifacts were observed with increasing rotation times > 0.2s for 16×1mm slice scan geometry. No significant increase in doubling artifacts was observed for 64×1mm slice scan geometry up to 1.0s rotation time although blurring artifacts were observed >0.6s. Using a 16×1mm slice scan geometry, a rotation time of less than 0.3s (53mm/s scan speed) would be required to produce images of similar quality to a 64×1mm slice scan geometry. Conclusion: The current generation of 16 slice CT scanners, which are present in most Radiation Oncology departments, are not capable of generating free-breathing sorting-artifact-free images in the majority of patients. The next generation of CT scanners should be capable of at least 53mm/s scan speed

  18. Single-shot x-ray phase contrast imaging with an algorithmic approach using spectral detection

    NASA Astrophysics Data System (ADS)

    Das, Mini; Park, Chan-Soo; Fredette, Nathaniel R.

    2016-04-01

    X-ray phase contrast imaging has been investigated during the last two decades for potential benefits in soft tissue imaging. Long imaging time, high radiation dose and general measurement complexity involving motion of x-ray optical components have prevented the clinical translation of these methods. In all existing popular phase contrast imaging methods, multiple measurements per projection angle involving motion of optical components are required to achieve quantitatively accurate estimation of absorption, phase and differential phase. Recently we proposed an algorithmic approach to use spectral detection data in a phase contrast imaging setup to obtain absorption, phase and differential phase in a single-step. Our generic approach has been shown via simulations in all three types of phase contrast imaging: propagation, coded aperture and grating interferometry. While other groups have used spectral detector in phase contrast imaging setups, our proposed method is unique in outlining an approach to use this spectral data to simplify phase contrast imaging. In this abstract we show the first experimental proof of our single-shot phase retrieval using a Medipix3 photon counting detector in an edge illumination aperture (also referred to as coded aperture) phase contrast set up as well as for a free space propagation setup. Our preliminary results validate our new transport equation for edge illumination PCI and our spectral phase retrieval algorithm for both PCI methods being investigated. Comparison with simulations also point to excellent performance of Medipix3 built-in charge sharing correction mechanism.

  19. Evaluation of edge effect due to phase contrast imaging for mammography

    SciTech Connect

    Matsuo, Satoru; Katafuchi, Tetsuro; Tohyama, Keiko; Morishita, Junji; Yamada, Katsuhiko; Fujita, Hiroshi

    2005-08-15

    It is well-known that the edge effect produced by phase contrast imaging results in the edge enhancement of x-ray images and thereby sharpens those images. It has recently been reported that phase contrast imaging using practical x-ray tubes with small focal spots has improved image sharpness as observed in the phase contrast imaging with x-ray from synchrotron radiation or micro-focus x-ray tubes. In this study, we conducted the phase contrast imaging of a plastic fiber and plant seeds using a customized mammography equipment with a 0.1 mm focal spot, and the improvement of image sharpness was evaluated in terms of spatial frequency response of the images. We observed that the image contrast of the plastic fiber was increased by edge enhancement, and, as predicted elsewhere, spectral analysis revealed that as the spatial frequencies of the x-ray images increased, so did the sharpness gained through phase contrast imaging. Thus, phase contrast imaging using a practical molybdenum anode tube with a 0.1 mm-focal spot would benefit mammography, in which the morphological detectability of small species such as micro-calcifications is of great concern. And detectability of tumor-surrounded glandular tissues in dense breast would be also improved by the phase contrast imaging.

  20. Abdominal Adhesions

    MedlinePlus

    ... Abdominal Adhesions 1 Ward BC, Panitch A. Abdominal adhesions: current and novel therapies. Journal of Surgical Research. 2011;165(1):91– ... are abdominal adhesions and intestinal obstructions ... generally do not require treatment. Surgery is the only way to treat abdominal ...

  1. Results from the first preclinical CT scanner with grating based phase contrast and a rotating gantry

    SciTech Connect

    Bech, Martin; Tapfer, Arne; Velroyen, Astrid; Yaroshenko, Andre; Pauwels, Bart; Bruyndonckx, Peter; Liu Xuan; Sasov, Alexander; Mohr, Juergen; Walter, Marco; Pfeiffer, Franz

    2012-07-31

    After successful demonstrations of soft-tissue phase-contrast imaging with grating interferometers at synchrotron radiation sources and at laboratory based x-ray tubes, a first preclinical CT scanner with grating based phase contrast imaging modality has been constructed. The rotating gantry is equipped with a three-grating interferometer, a 50 watt tungsten anode source and a Hamamatsu flat panel detector. The total length of the interferometer is 45 cm, and the bed of the scanner is optimized for mice, with a scanning diameter of 35 mm. From one single scan both phase-contrast and standard attenuation based tomography can be attained, providing an overall gain in image contrast.

  2. Grating-based X-ray phase contrast for biomedical imaging applications.

    PubMed

    Pfeiffer, Franz; Herzen, Julia; Willner, Marian; Chabior, Michael; Auweter, Sigrid; Reiser, Maximilian; Bamberg, Fabian

    2013-09-01

    In this review article we describe the development of grating-based X-ray phase-contrast imaging, with particular emphasis on potential biomedical applications of the technology. We review the basics of image formation in grating-based phase-contrast and dark-field radiography and present some exemplary multimodal radiography results obtained with laboratory X-ray sources. Furthermore, we discuss the theoretical concepts to extend grating-based multimodal radiography to quantitative transmission, phase-contrast, and dark-field scattering computed tomography. PMID:23453793

  3. Results from the first preclinical CT scanner with grating based phase contrast and a rotating gantry

    NASA Astrophysics Data System (ADS)

    Bech, Martin; Tapfer, Arne; Velroyen, Astrid; Yaroshenko, Andre; Pauwels, Bart; Bruyndonckx, Peter; Liu, Xuan; Sasov, Alexander; Mohr, Jürgen; Walter, Marco; Pfeiffer, Franz

    2012-07-01

    After successful demonstrations of soft-tissue phase-contrast imaging with grating interferometers at synchrotron radiation sources and at laboratory based x-ray tubes, a first preclinical CT scanner with grating based phase contrast imaging modality has been constructed. The rotating gantry is equipped with a three-grating interferometer, a 50 watt tungsten anode source and a Hamamatsu flat panel detector. The total length of the interferometer is 45 cm, and the bed of the scanner is optimized for mice, with a scanning diameter of 35 mm. From one single scan both phase-contrast and standard attenuation based tomography can be attained, providing an overall gain in image contrast.

  4. Grating-based x-ray phase-contrast imaging at PETRA III

    NASA Astrophysics Data System (ADS)

    Hipp, A.; Beckmann, F.; Lytaev, P.; Greving, I.; Lottermoser, L.; Dose, T.; Kirchhof, R.; Burmester, H.; Schreyer, A.; Herzen, J.

    2014-09-01

    Conventional absorption-based imaging often lacks in good contrast at special applications like visualization of soft tissue or weak absorbing material in general. To overcome this limitation, several new X-ray phase-contrast imaging methods have been developed at synchrotron radiation facilities. Our aim was to establish the possibility of different phase-contrast imaging modalities at the Imaging Beamline (IBL, P05) and the High Energy Material Science beamline (HEMS, P07) at Petra III (DESY, Germany). Here we present the instrumentation and the status of the currently successfully established phase-contrast imaging techniques. First results from measurements of biomedical samples will be presented as demonstration.

  5. Dosimetric comparison of treatment plans based on free breathing, maximum, and average intensity projection CTs for lung cancer SBRT

    SciTech Connect

    Tian Yuan; Wang Zhiheng; Ge Hong; Zhang Tian; Cai Jing; Kelsey, Christopher; Yoo, David; Yin Fangfang

    2012-05-15

    Purpose: To determine whether there is a CT dataset may be more favorable for planning and dose calculation by comparing dosimetric characteristics between treatment plans calculated using free breathing (FB), maximum and average intensity projection (MIP and AIP, respectively) CTs for lung cancer patients receiving stereotactic body radiation therapy (SBRT). Methods: Twenty lung cancer SBRT patients, treated on a linac with 2.5 mm width multileaf-collimator (MLC), were analyzed retrospectively. Both FB helical and four-dimensional CT scans were acquired for each patient. Internal target volume (ITV) was delineated based on MIP CTs and modified based on both ten-phase datasets and FB CTs. Planning target volume (PTV) was then determined by adding additional setup margin to ITV. The PTVs and beams in the optimized treatment plan based on FB CTs were copied to MIP and AIP CTs, with the same isocenters, MLC patterns and monitor units. Mean effective depth (MED) of beams, and some dosimetric parameters for both PTVs and most important organ at risk (OAR), lung minus PTV, were compared between any two datasets using two-tail paired t test. Results: The MEDs in FB and AIP plans were similar but significantly smaller (Ps < 0.001) than that in MIP plans. Minimum dose, mean dose, dose covering at least 90% and 95% of PTVs in MIP plans were slightly higher than two other plans (Ps < 0.008). The absolute volume of lung minus PTV receiving greater than 5, 10, and 20 Gy in MIP plans were significantly smaller than those in both FB and AIP plans (Ps < 0.008). Conformity index for FB plans showed a small but statistically significantly higher. Conclusions: Dosimetric characteristics of AIP plans are similar to those of FB plans. Slightly better target volume coverage and significantly lower low-dose region ({<=}30 Gy) in lung was observed in MIP plans. The decrease in low-dose region in lung was mainly caused by the change of lung volume contoured on two datasets rather than the

  6. Visualization of neurons in the brain with phase-contrast CT

    NASA Astrophysics Data System (ADS)

    Onodera, Hiroshi; Hoshino, Masato; Takashima, Kenta; Uesugi, Kentaro; Yagi, Naoto

    2012-07-01

    Three-dimensional structural analysis of brain is essential to understand neuronal function and brain pathology. The phase-contrast X-ray imaging technique uses an X-ray interferometer and is an extremely sensitive method to visualize structures with low X-ray absorbance. Since the phase shifts caused by light elements can be detected as interference patterns in spite of nearly zero absorption coefficients, the signal/noise ratio for the phase-contrast images of the brain is expected to be hundreds times higher than that obtained with the conventional X-ray absorption contrast method. With phase-contrast imaging technique, we could visualize brain microstructures and specific types of neurons, such as the pyramidal cells in the hippocampus. Phase-contrast CT is a promising technique for nondestructive visualization of brain and spinal cord.

  7. Quantitative Characterization of Inertial Confinement Fusion Capsules Using Phase Contrast Enhanced X-Ray Imaging

    SciTech Connect

    Kozioziemski, B J; Koch, J A; Barty, A; Martz, H E; Lee, W; Fezzaa, K

    2004-05-07

    Current designs for inertial confinement fusion capsules for the National Ignition Facility (NIF) consist of a solid deuterium-tritium (D-T) fuel layer inside of a copper doped beryllium capsule. Phase contrast enhanced x-ray imaging is shown to render the D-T layer visible inside the Be(Cu) capsule. Phase contrast imaging is experimentally demonstrated for several surrogate capsules and validates computational models. Polyimide and low density divinyl benzene foam capsules were imaged at the Advanced Photon Source synchrotron. The surrogates demonstrate that phase contrast enhanced imaging provides a method to characterize surfaces when absorption imaging cannot be used. Our computational models demonstrate that a rough surface can be accurately reproduced in phase contrast enhanced x-ray images.

  8. Three-dimensional phase-contrast imaging of single floating cells

    SciTech Connect

    Kobayashi, Hiroaki; Ishimaru, Ichirou; Yasokawa, Toshiki; Ishizaki, Katsumi; Kuriyama, Shigeki; Masaki, Tsutomu; Nakai, Seiji; Takegawa, Kaoru; Tanaka, Naotaka

    2006-12-11

    A three-dimensional phase-contrast imaging technique that does not involve fluorescent labeling has been developed for observing floating cells. In this method, a single floating cell is made to rotate and images are acquired at several orientations of the cell using a phase-contrast microscope. From these two-dimensional phase-contrast images, three-dimensional cross-sectional images are obtained using the conventional computed tomography algorithm. This proposed method enabled successful rotation of a floating cell (a breast cancer cell line) and reconstruction of three-dimensional phase-contrast images. In these reconstructed three-dimensional images, the distribution of cell organelles is obtained and the cell nucleus is clearly distinguishable.

  9. A phantom study to characterize the imaging quality of a phase-contrast tomosynthesis prototype

    NASA Astrophysics Data System (ADS)

    Wu, Di; Ghani, Muhammad U.; Miao, Hui; Li, Yuhua; Chen, Wei R.; Wu, Xizeng; Liu, Hong

    2013-02-01

    This research is aimed at studying the advantages of an x-ray phase-contrast tomosynthesis prototype by using phantoms. A prototype system is assembled with a micro-focus x-ray source, a rotating stage and a computed radiography detector mounted on an optical rail. A custom designed bubble wrap phantom is used in experiments. Angular projection images are acquired from -20° to +20° with 2° interval. The in-plane slices are reconstructed. The feature area on the phantom is observed. The prototype system provides an intrinsic way to investigate the potential and imaging quality of a phase-contrast tomosynthesis imaging method. As the result, phase-contrast tomosynthesis imaging method is demonstrated for its advantages in avoiding structure noise and overlapping issues by comparing the results acquired by computed radiography and phase-contrast radiography.

  10. In-line phase-contrast imaging based on Tsinghua Thomson scattering x-ray source.

    PubMed

    Zhang, Zhen; Du, Yingchao; Yan, Lixin; Hua, Jianfei; Yang, Jin; Xiao, Yongshun; Huang, Wenhui; Chen, Huaibi; Tang, Chuanxiang

    2014-08-01

    Thomson scattering x-ray sources can produce ultrashort, energy tunable x-ray pulses characterized by high brightness, quasi-monochromatic, and high spatial coherence, which make it an ideal source for in-line phase-contrast imaging. We demonstrate the capacity of in-line phase-contrast imaging based on Tsinghua Thomson scattering X-ray source. Clear edge enhancement effect has been observed in the experiment. PMID:25173262

  11. Image fusion in x-ray differential phase-contrast imaging

    NASA Astrophysics Data System (ADS)

    Haas, W.; Polyanskaya, M.; Bayer, F.; Gödel, K.; Hofmann, H.; Rieger, J.; Ritter, A.; Weber, T.; Wucherer, L.; Durst, J.; Michel, T.; Anton, G.; Hornegger, J.

    2012-02-01

    Phase-contrast imaging is a novel modality in the field of medical X-ray imaging. The pioneer method is the grating-based interferometry which has no special requirements to the X-ray source and object size. Furthermore, it provides three different types of information of an investigated object simultaneously - absorption, differential phase-contrast and dark-field images. Differential phase-contrast and dark-field images represent a completely new information which has not yet been investigated and studied in context of medical imaging. In order to introduce phase-contrast imaging as a new modality into medical environment the resulting information about the object has to be correctly interpreted. The three output images reflect different properties of the same object the main challenge is to combine and visualize these data in such a way that it diminish the information explosion and reduce the complexity of its interpretation. This paper presents an intuitive image fusion approach which allows to operate with grating-based phase-contrast images. It combines information of the three different images and provides a single image. The approach is implemented in a fusion framework which is aimed to support physicians in study and analysis. The framework provides the user with an intuitive graphical user interface allowing to control the fusion process. The example given in this work shows the functionality of the proposed method and the great potential of phase-contrast imaging in medical practice.

  12. Quantitative breast tissue characterization using grating-based x-ray phase-contrast imaging.

    PubMed

    Willner, M; Herzen, J; Grandl, S; Auweter, S; Mayr, D; Hipp, A; Chabior, M; Sarapata, A; Achterhold, K; Zanette, I; Weitkamp, T; Sztrókay, A; Hellerhoff, K; Reiser, M; Pfeiffer, F

    2014-04-01

    X-ray phase-contrast imaging has received growing interest in recent years due to its high capability in visualizing soft tissue. Breast imaging became the focus of particular attention as it is considered the most promising candidate for a first clinical application of this contrast modality. In this study, we investigate quantitative breast tissue characterization using grating-based phase-contrast computed tomography (CT) at conventional polychromatic x-ray sources. Different breast specimens have been scanned at a laboratory phase-contrast imaging setup and were correlated to histopathology. Ascertained tumor types include phylloides tumor, fibroadenoma and infiltrating lobular carcinoma. Identified tissue types comprising adipose, fibroglandular and tumor tissue have been analyzed in terms of phase-contrast Hounsfield units and are compared to high-quality, high-resolution data obtained with monochromatic synchrotron radiation, as well as calculated values based on tabulated tissue properties. The results give a good impression of the method's prospects and limitations for potential tumor detection and the associated demands on such a phase-contrast breast CT system. Furthermore, the evaluated quantitative tissue values serve as a reference for simulations and the design of dedicated phantoms for phase-contrast mammography. PMID:24614413

  13. Quantitative breast tissue characterization using grating-based x-ray phase-contrast imaging

    NASA Astrophysics Data System (ADS)

    Willner, M.; Herzen, J.; Grandl, S.; Auweter, S.; Mayr, D.; Hipp, A.; Chabior, M.; Sarapata, A.; Achterhold, K.; Zanette, I.; Weitkamp, T.; Sztrókay, A.; Hellerhoff, K.; Reiser, M.; Pfeiffer, F.

    2014-04-01

    X-ray phase-contrast imaging has received growing interest in recent years due to its high capability in visualizing soft tissue. Breast imaging became the focus of particular attention as it is considered the most promising candidate for a first clinical application of this contrast modality. In this study, we investigate quantitative breast tissue characterization using grating-based phase-contrast computed tomography (CT) at conventional polychromatic x-ray sources. Different breast specimens have been scanned at a laboratory phase-contrast imaging setup and were correlated to histopathology. Ascertained tumor types include phylloides tumor, fibroadenoma and infiltrating lobular carcinoma. Identified tissue types comprising adipose, fibroglandular and tumor tissue have been analyzed in terms of phase-contrast Hounsfield units and are compared to high-quality, high-resolution data obtained with monochromatic synchrotron radiation, as well as calculated values based on tabulated tissue properties. The results give a good impression of the method’s prospects and limitations for potential tumor detection and the associated demands on such a phase-contrast breast CT system. Furthermore, the evaluated quantitative tissue values serve as a reference for simulations and the design of dedicated phantoms for phase-contrast mammography.

  14. A comparative analysis of 3D conformal deep inspiratory–breath hold and free-breathing intensity-modulated radiation therapy for left-sided breast cancer

    SciTech Connect

    Reardon, Kelli A.; Read, Paul W.; Morris, Monica M.; Reardon, Michael A.; Geesey, Constance; Wijesooriya, Krishni

    2013-07-01

    Patients undergoing radiation for left-sided breast cancer have increased rates of coronary artery disease. Free-breathing intensity-modulated radiation therapy (FB-IMRT) and 3-dimensional conformal deep inspiratory–breath hold (3D-DIBH) reduce cardiac irradiation. The purpose of this study is to compare the dose to organs at risk in FB-IMRT vs 3D-DIBH for patients with left-sided breast cancer. Ten patients with left-sided breast cancer had 2 computed tomography scans: free breathing and voluntary DIBH. Optimization of the IMRT plan was performed on the free-breathing scan using 6 noncoplanar tangential beams. The 3D-DIBH plan was optimized on the DIBH scan and used standard tangents. Mean volumes of the heart, the left anterior descending coronary artery (LAD), the total lung, and the right breast receiving 5% to 95% (5% increments) of the prescription dose were calculated. Mean volumes of the heart and the LAD were lower (p<0.05) in 3D-DIBH for volumes receiving 5% to 80% of the prescription dose for the heart and 5% for the LAD. Mean dose to the LAD and heart were lower in 3D-DIBH (p≤0.01). Mean volumes of the total lung were lower in FB-IMRT for dose levels 20% to 75% (p<0.05), but mean dose was not different. Mean volumes of the right breast were not different for any dose; however, mean dose was lower for 3D-DIBH (p = 0.04). 3D-DIBH is an alternative approach to FB-IMRT that provides a clinically equivalent treatment for patients with left-sided breast cancer while sparing organs at risk with increased ease of implementation.

  15. Free-breathing diffusion tensor imaging and tractography of the human heart in healthy volunteers using wavelet-based image fusion.

    PubMed

    Wei, Hongjiang; Viallon, Magalie; Delattre, Benedicte M A; Moulin, Kevin; Yang, Feng; Croisille, Pierre; Zhu, Yuemin

    2015-01-01

    Free-breathing cardiac diffusion tensor imaging (DTI) is a promising but challenging technique for the study of fiber structures of the human heart in vivo. This work proposes a clinically compatible and robust technique to provide three-dimensional (3-D) fiber architecture properties of the human heart. To this end, 10 short-axis slices were acquired across the entire heart using a multiple shifted trigger delay (TD) strategy under free breathing conditions. Interscan motion was first corrected automatically using a nonrigid registration method. Then, two post-processing schemes were optimized and compared: an algorithm based on principal component analysis (PCA) filtering and temporal maximum intensity projection (TMIP), and an algorithm that uses the wavelet-based image fusion (WIF) method. The two methods were applied to the registered diffusion-weighted (DW) images to cope with intrascan motion-induced signal loss. The tensor fields were finally calculated, from which fractional anisotropy (FA), mean diffusivity (MD), and 3-D fiber tracts were derived and compared. The results show that the comparison of the FA values (FA(PCATMIP) = 0.45 ±0.10, FA(WIF) = 0.42 ±0.05, P=0.06) showed no significant difference, while the MD values ( MD(PCATMIP)=0.83 ±0.12×10(-3) mm (2)/s, MD(WIF)=0.74±0.05×10(-3) mm (2)/s, P=0.028) were significantly different. Improved helix angle variations through the myocardium wall reflecting the rotation characteristic of cardiac fibers were observed with WIF. This study demonstrates that the combination of multiple shifted TD acquisitions and dedicated post-processing makes it feasible to retrieve in vivo cardiac tractographies from free-breathing DTI acquisitions. The substantial improvements were observed using the WIF method instead of the previously published PCATMIP technique. PMID:25216480

  16. Abdominal mass

    MedlinePlus

    Several conditions can cause an abdominal mass: Abdominal aortic aneurysm can cause a pulsating mass around the navel. ... This could be a sign of a ruptured aortic aneurysm, which is an emergency condition. Contact your health ...

  17. Abdominal mass

    MedlinePlus

    ... Several conditions can cause an abdominal mass: Abdominal aortic aneurysm can cause a pulsating mass around the navel. ... This could be a sign of a ruptured aortic aneurysm, which is an emergency condition. Contact your health ...

  18. Noise properties of grating-based x-ray phase contrast computed tomography

    SciTech Connect

    Koehler, Thomas; Juergen Engel, Klaus; Roessl, Ewald

    2011-05-15

    Purpose: To investigate the properties of tomographic grating-based phase contrast imaging with respect to its noise power spectrum and the energy dependence of the achievable contrast to noise ratio. Methods: Tomographic simulations of an object with 11 cm diameter constituted of materials of biological interest were conducted at different energies ranging from 25 to 85 keV by using a wave propagation approach. Using a Monte Carlo simulation of the x-ray attenuation within the object, it is verified that the simulated measurement deposits the same dose within the object at each energy. Results: The noise in reconstructed phase contrast computed tomography images shows a maximum at low spatial frequencies. The contrast to noise ratio reaches a maximum around 45 keV for the simulated object. The general dependence of the contrast to noise on the energy appears to be independent of the material. Compared with reconstructed absorption contrast images, the reconstructed phase contrast images show sometimes better, sometimes worse, and sometimes similar contrast to noise, depending on the material and the energy. Conclusions: Phase contrast images provide additional information to the conventional absorption contrast images and might thus be useful for medical applications. However, the observed noise power spectrum in reconstructed phase contrast images implies that the usual trade-off between noise and resolution is less efficient for phase contrast imaging compared with absorption contrast imaging. Therefore, high-resolution imaging is a strength of phase contrast imaging, but low-resolution imaging is not. This might hamper the clinical application of the method, in cases where a low spatial resolution is sufficient for diagnosis.

  19. X-Ray Phase-Contrast CT of a Pancreatic Ductal Adenocarcinoma Mouse Model

    PubMed Central

    Tapfer, Arne; Braren, Rickmer; Bech, Martin; Willner, Marian; Zanette, Irene; Weitkamp, Timm; Trajkovic-Arsic, Marija; Siveke, Jens T.; Settles, Marcus; Aichler, Michaela; Walch, Axel; Pfeiffer, Franz

    2013-01-01

    To explore the potential of grating-based x-ray phase-contrast computed tomography (CT) for preclinical research, a genetically engineered mouse model of pancreatic ductal adenocarcinoma (PDAC) was investigated. One ex-vivo mouse specimen was scanned with different grating-based phase-contrast CT imaging setups covering two different settings: i) high-resolution synchrotron radiation (SR) imaging and ii) dose-reduced imaging using either synchrotron radiation or a conventional x-ray tube source. These experimental settings were chosen to assess the potential of phase-contrast imaging for two different types of application: i) high-performance imaging for virtual microscopy applications and ii) biomedical imaging with increased soft-tissue contrast for in-vivo applications. For validation and as a reference, histological slicing and magnetic resonance imaging (MRI) were performed on the same mouse specimen. For each x-ray imaging setup, attenuation and phase-contrast images were compared visually with regard to contrast in general, and specifically concerning the recognizability of lesions and cancerous tissue. To quantitatively assess contrast, the contrast-to-noise ratios (CNR) of selected regions of interest (ROI) in the attenuation images and the phase images were analyzed and compared. It was found that both for virtual microscopy and for in-vivo applications, there is great potential for phase-contrast imaging: in the SR-based benchmarking data, fine details about tissue composition are accessible in the phase images and the visibility of solid tumor tissue under dose-reduced conditions is markedly superior in the phase images. The present study hence demonstrates improved diagnostic value with phase-contrast CT in a mouse model of a complex endogenous cancer, promoting the use and further development of grating-based phase-contrast CT for biomedical imaging applications. PMID:23536795

  20. Report of improved performance in Talbot–Lau phase-contrast computed tomography

    SciTech Connect

    Weber, Thomas Pelzer, Georg; Rieger, Jens; Ritter, André; Anton, Gisela

    2015-06-15

    Purpose: Many expectations have been raised since the use of conventional x-ray tubes on grating-based x-ray phase-contrast imaging. Despite a reported increase in contrast-to-noise ratio (CNR) in many publications, there is doubt on whether phase-contrast computed tomography (CT) is advantageous in clinical CT scanners in vivo. The aim of this paper is to contribute to this discussion by analyzing the performance of a phase-contrast CT laboratory setup. Methods: A phase-contrast CT performance analysis was done. Projection images of a phantom were recorded, and image slices were reconstructed using standard filtered back projection methods. The resulting image slices were analyzed by determining the CNRs in the attenuation and phase image. These results were compared to analytically calculated expectations according to the already published phase-contrast CT performance analysis by Raupach and Flohr [Med. Phys. 39, 4761–4774 (2012)]. There, a severe mistake was found leading to wrong predictions of the performance of phase-contrast CT. The error was corrected and with the new formulae, the experimentally obtained results matched the analytical calculations. Results: The squared ratios of the phase-contrast CNR and the attenuation CNR obtained in the authors’ experiment are five- to ten-fold higher than predicted by Raupach and Flohr [Med. Phys. 39, 4761–4774 (2012)]. The effective lateral spatial coherence length deduced outnumbers the already optimistic assumption of Raupach and Flohr [Med. Phys. 39, 4761–4774 (2012)] by a factor of 3. Conclusions: The authors’ results indicate that the assumptions made in former performance analyses are pessimistic. The break-even point, when phase-contrast CT outperforms attenuation CT, is within reach even with realistic, nonperfect gratings. Further improvements to state-of-the-art clinical CT scanners, like increasing the spatial resolution, could change the balance in favor of phase-contrast computed tomography

  1. Visualizing Typical Features of Breast Fibroadenomas Using Phase-Contrast CT: An Ex-Vivo Study

    PubMed Central

    Grandl, Susanne; Willner, Marian; Herzen, Julia; Sztrókay-Gaul, Anikó; Mayr, Doris; Auweter, Sigrid D.; Hipp, Alexander; Birnbacher, Lorenz; Marschner, Mathias; Chabior, Michael; Reiser, Maximilian; Pfeiffer, Franz; Bamberg, Fabian; Hellerhoff, Karin

    2014-01-01

    Background Fibroadenoma is the most common benign solid breast lesion type and a very common cause for histologic assessment. To justify a conservative therapy, a highly specific discrimination between fibroadenomas and other breast lesions is crucial. Phase-contrast imaging offers improved soft-tissue contrast and differentiability of fine structures combined with the potential of 3-dimensional imaging. In this study we assessed the potential of grating-based phase-contrast CT imaging for visualizing diagnostically relevant features of fibroadenomas. Materials and Methods Grating-based phase-contrast CT was performed on six ex-vivo formalin-fixed breast specimens containing a fibroadenoma and three samples containing benign changes that resemble fibroadenomas using Talbot Lau interferometry and a polychromatic X-ray source. Phase-contrast and simultaneously acquired absorption-based 3D-datasets were manually matched with corresponding histological slices. The visibility of diagnostically valuable features was assessed in comparison with histology as the gold-standard. Results In all cases, matching of grating-based phase-contrast CT images and histology was successfully completed. Grating-based phase-contrast CT showed greatly improved differentiation of fine structures and provided accurate depiction of strands of fibrous tissue within the fibroadenomas as well as of the diagnostically valuable dilated, branched ductuli of the fibroadenomas. A clear demarcation of tumor boundaries in all cases was provided by phase- but not absorption-contrast CT. Conclusions Pending successful translation of the technology to a clinical setting and considerable reduction of the required dose, the data presented here suggest that grating-based phase-contrast CT may be used as a supplementary non-invasive diagnostic tool in breast diagnostics. Phase-contrast CT may thus contribute to the reduction of false positive findings and reduce the recall and core biopsy rate in population

  2. Image segmentation of nanoscale Zernike phase contrast X-ray computed tomography images

    SciTech Connect

    Kumar, Arjun S.; Mandal, Pratiti; Zhang, Yongjie; Litster, Shawn

    2015-05-14

    Zernike phase contrast is a useful technique for nanoscale X-ray computed tomography (CT) imaging of materials with a low X-ray absorption coefficient. It enhances the image contrast by phase shifting X-ray waves to create changes in amplitude. However, it creates artifacts that hinder the use of traditional image segmentation techniques. We propose an image restoration method that models the X-ray phase contrast optics and the three-dimensional image reconstruction method. We generate artifact-free images through an optimization problem that inverts this model. Though similar approaches have been used for Zernike phase contrast in visible light microscopy, this optimization employs an effective edge detection method tailored to handle Zernike phase contrast artifacts. We characterize this optics-based restoration method by removing the artifacts in and thresholding multiple Zernike phase contrast X-ray CT images to produce segmented results that are consistent with the physical specimens. We quantitatively evaluate and compare our method to other segmentation techniques to demonstrate its high accuracy.

  3. Breast tumor segmentation in high resolution x-ray phase contrast analyzer based computed tomography

    SciTech Connect

    Brun, E.; Grandl, S.; Sztrókay-Gaul, A.; Gasilov, S.; Barbone, G.; Mittone, A.; Coan, P.; Bravin, A.

    2014-11-01

    Purpose: Phase contrast computed tomography has emerged as an imaging method, which is able to outperform present day clinical mammography in breast tumor visualization while maintaining an equivalent average dose. To this day, no segmentation technique takes into account the specificity of the phase contrast signal. In this study, the authors propose a new mathematical framework for human-guided breast tumor segmentation. This method has been applied to high-resolution images of excised human organs, each of several gigabytes. Methods: The authors present a segmentation procedure based on the viscous watershed transform and demonstrate the efficacy of this method on analyzer based phase contrast images. The segmentation of tumors inside two full human breasts is then shown as an example of this procedure’s possible applications. Results: A correct and precise identification of the tumor boundaries was obtained and confirmed by manual contouring performed independently by four experienced radiologists. Conclusions: The authors demonstrate that applying the watershed viscous transform allows them to perform the segmentation of tumors in high-resolution x-ray analyzer based phase contrast breast computed tomography images. Combining the additional information provided by the segmentation procedure with the already high definition of morphological details and tissue boundaries offered by phase contrast imaging techniques, will represent a valuable multistep procedure to be used in future medical diagnostic applications.

  4. X-ray phase-contrast imaging of the breast—advances towards clinical implementation

    PubMed Central

    Herzen, J; Willner, M; Grandl, S; Scherer, K; Bamberg, F; Reiser, M F; Pfeiffer, F; Hellerhoff, K

    2014-01-01

    Breast cancer constitutes about one-quarter of all cancers and is the leading cause of cancer death in women. To reduce breast cancer mortality, mammographic screening programmes have been implemented in many Western countries. However, these programmes remain controversial because of the associated radiation exposure and the need for improvement in terms of diagnostic accuracy. Phase-contrast imaging is a new X-ray-based technology that has been shown to provide enhanced soft-tissue contrast and improved visualization of cancerous structures. Furthermore, there is some indication that these improvements of image quality can be maintained at reduced radiation doses. Thus, X-ray phase-contrast mammography may significantly contribute to advancements in early breast cancer diagnosis. Feasibility studies of X-ray phase-contrast breast CT have provided images that allow resolution of the fine structure of tissue that can otherwise only be obtained by histology. This implies that X-ray phase-contrast imaging may also lead to the development of entirely new (micro-) radiological applications. This review provides a brief overview of the physical characteristics of this new technology and describes recent developments towards clinical implementation of X-ray phase-contrast imaging of the breast. PMID:24452106

  5. Artifact characterization and reduction in scanning X-ray Zernike phase contrast microscopy.

    PubMed

    Vartiainen, Ismo; Holzner, Christian; Mohacsi, Istvan; Karvinen, Petri; Diaz, Ana; Pigino, Gaia; David, Christian

    2015-05-18

    Zernike phase contrast microscopy is a well-established method for imaging specimens with low absorption contrast. It has been successfully implemented in full-field microscopy using visible light and X-rays. In microscopy Cowley's reciprocity principle connects scanning and full-field imaging. Even though the reciprocity in Zernike phase contrast has been discussed by several authors over the past thirty years, only recently it was experimentally verified using scanning X-ray microscopy. In this paper, we investigate the image and contrast formation in scanning Zernike phase contrast microscopy with a particular and detailed focus on the origin of imaging artifacts that are typically associated with Zernike phase contrast. We demonstrate experimentally with X-rays the effect of the phase mask design on the contrast and halo artifacts and present an optimized design of the phase mask with respect to photon efficiency and artifact reduction. Similarly, due to the principle of reciprocity the observations and conclusions of this work have direct applicability to Zernike phase contrast in full-field microscopy as well. PMID:26074579

  6. Dynamic measures of regional lung air volume using phase contrast x-ray imaging

    NASA Astrophysics Data System (ADS)

    Kitchen, M. J.; Lewis, R. A.; Morgan, M. J.; Wallace, M. J.; Siew, M. L.; Siu, K. K. W.; Habib, A.; Fouras, A.; Yagi, N.; Uesugi, K.; Hooper, S. B.

    2008-11-01

    Phase contrast x-ray imaging can provide detailed images of lung morphology with sufficient spatial resolution to observe the terminal airways (alveoli). We demonstrate that quantitative functional and anatomical imaging of lung ventilation can be achieved in vivo using two-dimensional phase contrast x-ray images with high contrast and spatial resolution (<100 µm) in near real time. Changes in lung air volume as small as 25 µL were calculated from the images of term and preterm rabbit pup lungs (n = 28) using a single-image phase retrieval algorithm. Comparisons with plethysmography and computed tomography showed that the technique provided an accurate and robust method of measuring total lung air volumes. Furthermore, regional ventilation was measured by partitioning the phase contrast images, which revealed differences in aeration for different ventilation strategies.

  7. Interferometric hard x-ray phase contrast imaging at 204 nm grating period

    SciTech Connect

    Wen Han; Gomella, Andrew A.; Miao, Houxun; Lynch, Susanna K.; Wolfe, Douglas E.; Xiao Xianghui; Liu Chian; Morgan, Nicole

    2013-01-15

    We report on hard x-ray phase contrast imaging experiments using a grating interferometer of approximately 1/10th the grating period achieved in previous studies. We designed the gratings as a staircase array of multilayer stacks which are fabricated in a single thin film deposition process. We performed the experiments at 19 keV x-ray energy and 0.8 {mu}m pixel resolution. The small grating period resulted in clear separation of different diffraction orders and multiple images on the detector. A slitted beam was used to remove overlap of the images from the different diffraction orders. The phase contrast images showed detailed features as small as 10 {mu}m, and demonstrated the feasibility of high resolution x-ray phase contrast imaging with nanometer scale gratings.

  8. Optical Fourier techniques for medical image processing and phase contrast imaging

    PubMed Central

    Yelleswarapu, Chandra S.; Kothapalli, Sri-Rajasekhar; Rao, D.V.G.L.N.

    2008-01-01

    This paper briefly reviews the basics of optical Fourier techniques (OFT) and applications for medical image processing as well as phase contrast imaging of live biological specimens. Enhancement of microcalcifications in a mammogram for early diagnosis of breast cancer is the main focus. Various spatial filtering techniques such as conventional 4f filtering using a spatial mask, photoinduced polarization rotation in photosensitive materials, Fourier holography, and nonlinear transmission characteristics of optical materials are discussed for processing mammograms. We also reviewed how the intensity dependent refractive index can be exploited as a phase filter for phase contrast imaging with a coherent source. This novel approach represents a significant advance in phase contrast microscopy. PMID:18458764

  9. Optical Fourier techniques for medical image processing and phase contrast imaging.

    PubMed

    Yelleswarapu, Chandra S; Kothapalli, Sri-Rajasekhar; Rao, D V G L N

    2008-04-01

    This paper briefly reviews the basics of optical Fourier techniques (OFT) and applications for medical image processing as well as phase contrast imaging of live biological specimens. Enhancement of microcalcifications in a mammogram for early diagnosis of breast cancer is the main focus. Various spatial filtering techniques such as conventional 4f filtering using a spatial mask, photoinduced polarization rotation in photosensitive materials, Fourier holography, and nonlinear transmission characteristics of optical materials are discussed for processing mammograms. We also reviewed how the intensity dependent refractive index can be exploited as a phase filter for phase contrast imaging with a coherent source. This novel approach represents a significant advance in phase contrast microscopy. PMID:18458764

  10. X-ray elastography: Modification of x-ray phase contrast images using ultrasonic radiation pressure

    SciTech Connect

    Hamilton, Theron J.; Bailat, Claude; Rose-Petruck, Christoph; Diebold, Gerald J.; Gehring, Stephan; Laperle, Christopher M.; Wands, Jack

    2009-05-15

    The high resolution characteristic of in-line x-ray phase contrast imaging can be used in conjunction with directed ultrasound to detect small displacements in soft tissue generated by differential acoustic radiation pressure. The imaging method is based on subtraction of two x-ray images, the first image taken with, and the second taken without the presence of ultrasound. The subtraction enhances phase contrast features and, to a large extent, removes absorption contrast so that differential movement of tissues with different acoustic impedances or relative ultrasonic absorption is highlighted in the image. Interfacial features of objects with differing densities are delineated in the image as a result of both the displacement introduced by the ultrasound and the inherent sensitivity of x-ray phase contrast imaging to density variations. Experiments with ex vivo murine tumors and human tumor phantoms point out a diagnostic capability of the method for identifying tumors.

  11. Analysis of speckle patterns in phase-contrast images of lung tissue

    NASA Astrophysics Data System (ADS)

    Kitchen, M. J.; Paganin, D.; Lewis, R. A.; Yagi, N.; Uesugi, K.

    2005-08-01

    Propagation-based phase-contrast images of mice lungs have been obtained at the SPring-8 synchrotron research facility. Such images exhibit a speckled intensity pattern that bears a superficial resemblance to alveolar structures. This speckle results from focussing effects as projected air-filled alveoli form aberrated compound refractive lenses. An appropriate phase-retrieval algorithm has been utilized to reconstruct the approximate projected lung tissue thickness from single-phase-contrast mice chest radiographs. The results show projected density variations across the lung, highlighting regions of low density corresponding to air-filled regions. Potentially, this offers a better method than conventional radiography for detecting lung diseases such as fibrosis, emphysema and cancer, though this has yet to be demonstrated. As such, the approach can assist in continuing studies of lung function utilizing propagation-based phase-contrast imaging.

  12. Analytical reconstructions of intensity modulated x-ray phase-contrast imaging of human scale phantoms.

    PubMed

    Włodarczyk, Bartłomiej; Pietrzak, Jakub

    2015-11-01

    This paper presents analytical approach to modeling of a full planar and volumetric acquisition system with image reconstructions originated from partial illumination x-ray phase-contrast imaging at a human scale using graphics processor units. The model is based on x-ray tracing and wave optics methods to develop a numerical framework for predicting the performance of a preclinical phase-contrast imaging system of a human-scaled phantom. In this study, experimental images of simple numerical phantoms and high resolution anthropomorphic phantoms of head and thorax based on non-uniform rational b-spline shapes (NURBS) prove the correctness of the model. Presented results can be used to simulate the performance of partial illumination x-ray phase-contrast imaging system on various preclinical applications. PMID:26600991

  13. Analytical reconstructions of intensity modulated x-ray phase-contrast imaging of human scale phantoms

    PubMed Central

    Włodarczyk, Bartłomiej; Pietrzak, Jakub

    2015-01-01

    This paper presents analytical approach to modeling of a full planar and volumetric acquisition system with image reconstructions originated from partial illumination x-ray phase-contrast imaging at a human scale using graphics processor units. The model is based on x-ray tracing and wave optics methods to develop a numerical framework for predicting the performance of a preclinical phase-contrast imaging system of a human-scaled phantom. In this study, experimental images of simple numerical phantoms and high resolution anthropomorphic phantoms of head and thorax based on non-uniform rational b-spline shapes (NURBS) prove the correctness of the model. Presented results can be used to simulate the performance of partial illumination x-ray phase-contrast imaging system on various preclinical applications. PMID:26600991

  14. Variable multimodal light microscopy with interference contrast and phase contrast; dark or bright field.

    PubMed

    Piper, T; Piper, J

    2014-07-01

    Using the optical methods described, specimens can be observed with modified multimodal light microscopes based on interference contrast combined with phase contrast, dark- or bright-field illumination. Thus, the particular visual information associated with interference and phase contrast, dark- and bright-field illumination is joined in real-time composite images appearing in enhanced clarity and purified from typical artefacts, which are apparent in standard phase contrast and dark-field illumination. In particular, haloing and shade-off are absent or significantly reduced as well as marginal blooming and scattering. The background brightness and thus the range of contrast can be continuously modulated and variable transitions can be achieved between interference contrast and complementary illumination techniques. The methods reported should be of general interest for all disciplines using phase and interference contrast microscopy, especially in biology and medicine, and also in material sciences when implemented in vertical illuminators. PMID:24832212

  15. Fast grating-based X-ray phase-contrast tomosynthesis.

    PubMed

    Xi, Yan; Zhao, Jun

    2013-01-01

    As an imaging technique with low radiation dose and improved contrast, digital x-ray tomosynthesis is widely used in clinical diagnoses. Based on the superior capability of x-ray phase-contrast imaging (PCI) techniques for imaging low density materials, the combination of X-ray tomosynthesis and PCI can potentially provide higher efficiency in the detection of soft tissues. The goal of this work was to develop a fast imaging method for phase-contrast tomosynthesis, called fast grating-based phase-contrast tomosynthesis (GPC-Tomo), which integrates tomosynthesis with a grating-based PCI technique. Following the interlaced phase-stepping (PS) data collection method, which is much faster than conventional PS method, we propose a novel image reconstruction method called inner-focusing (IF) reconstruction for the fast GPC-Tomo. The proposed IF reconstruction method was validated by real experiments and the results suggested its effectiveness in achieving a fast GPC-Tomo. PMID:24110189

  16. Phase contrast imaging simulation and measurements using polychromatic sources with small source-object distances

    SciTech Connect

    Golosio, Bruno; Carpinelli, Massimo; Masala, Giovanni Luca; Oliva, Piernicola; Stumbo, Simone; Delogu, Pasquale; Zanette, Irene; Stefanini, Arnaldo

    2008-11-01

    Phase contrast imaging is a technique widely used in synchrotron facilities for nondestructive analysis. Such technique can also be implemented through microfocus x-ray tube systems. Recently, a relatively new type of compact, quasimonochromatic x-ray sources based on Compton backscattering has been proposed for phase contrast imaging applications. In order to plan a phase contrast imaging system setup, to evaluate the system performance and to choose the experimental parameters that optimize the image quality, it is important to have reliable software for phase contrast imaging simulation. Several software tools have been developed and tested against experimental measurements at synchrotron facilities devoted to phase contrast imaging. However, many approximations that are valid in such conditions (e.g., large source-object distance, small transverse size of the object, plane wave approximation, monochromatic beam, and Gaussian-shaped source focal spot) are not generally suitable for x-ray tubes and other compact systems. In this work we describe a general method for the simulation of phase contrast imaging using polychromatic sources based on a spherical wave description of the beam and on a double-Gaussian model of the source focal spot, we discuss the validity of some possible approximations, and we test the simulations against experimental measurements using a microfocus x-ray tube on three types of polymers (nylon, poly-ethylene-terephthalate, and poly-methyl-methacrylate) at varying source-object distance. It will be shown that, as long as all experimental conditions are described accurately in the simulations, the described method yields results that are in good agreement with experimental measurements.

  17. Phase-contrast enhanced mammography: A new diagnostic tool for breast imaging

    SciTech Connect

    Wang Zhentian; Thuering, Thomas; David, Christian; Roessl, Ewald; Trippel, Mafalda; Kubik-Huch, Rahel A.; Singer, Gad; Hohl, Michael K.; Hauser, Nik; Stampanoni, Marco

    2012-07-31

    Phase contrast and scattering-based X-ray imaging can potentially revolutionize the radiological approach to breast imaging by providing additional and complementary information to conventional, absorption-based methods. We investigated native, non-fixed whole breast samples using a grating interferometer with an X-ray tube-based configuration. Our approach simultaneously recorded absorption, differential phase contrast and small-angle scattering signals. The results show that this novel technique - combined with a dedicated image fusion algorithm - has the potential to deliver enhanced breast imaging with complementary information for an improved diagnostic process.

  18. Simple phase extraction in x-ray differential phase contrast imaging

    NASA Astrophysics Data System (ADS)

    Xin, Liu; Jin-Chuan, Guo; Yao-Hu, Lei; Ji, Li; Han-Ben, Niu

    2016-02-01

    A fast and simple method to extract phase-contrast images from interferograms is proposed, and its effectiveness is demonstrated through simulation and experiment. For x-ray differential phase contrast imaging, a strong attenuation signal acts as an overwhelming background intensity that obscures the weak phase signal so that no obvious phase-gradient information is detectable in the raw image. By subtracting one interferogram from another, chosen at particular intervals, the phase signal can be isolated and magnified. Project supported by the National Natural Science Foundation of China (Grant Nos. 61101175, 61571305, and 61227802).

  19. Phase-contrast enhanced mammography: A new diagnostic tool for breast imaging

    NASA Astrophysics Data System (ADS)

    Wang, Zhentian; Thuering, Thomas; David, Christian; Roessl, Ewald; Trippel, Mafalda; Kubik-Huch, Rahel A.; Singer, Gad; Hohl, Michael K.; Hauser, Nik; Stampanoni, Marco

    2012-07-01

    Phase contrast and scattering-based X-ray imaging can potentially revolutionize the radiological approach to breast imaging by providing additional and complementary information to conventional, absorption-based methods. We investigated native, non-fixed whole breast samples using a grating interferometer with an X-ray tube-based configuration. Our approach simultaneously recorded absorption, differential phase contrast and small-angle scattering signals. The results show that this novel technique - combined with a dedicated image fusion algorithm - has the potential to deliver enhanced breast imaging with complementary information for an improved diagnostic process.

  20. Simplified approach for quantitative digital holographic phase contrast imaging of living cells

    NASA Astrophysics Data System (ADS)

    Kemper, Björn; Vollmer, Angelika; Rommel, Christina E.; Schnekenburger, Jürgen; Bally, Gert Von

    2011-02-01

    Many interferometry-based quantitative phase contrast imaging techniques require a separately generated coherent reference wave. This results in a low phase stability and the demand for a precise adjustment of the intensity ratio between object and reference wave. To overcome these problems, the performance of a Michelson interferometer approach for digital holographic microscopy was analyzed that avoids a separately generated reference wave by superposition of different image areas. It is shown that this simplified arrangement yields improved phase stability. Furthermore, results from time-lapse investigations on living pancreas tumor cells demonstrate the capability of the method for reliable quantitative phase contrast imaging.

  1. Heralded phase-contrast imaging using an orbital angular momentum phase-filter

    NASA Astrophysics Data System (ADS)

    Aspden, Reuben S.; Morris, Peter A.; He, Ruiqing; Chen, Qian; Padgett, Miles J.

    2016-05-01

    We utilise the position and orbital angular momentum (OAM) correlations between the signal and idler photons generated in the down-conversion process to obtain ghost images of a phase object. By using an OAM phase filter, which is non-local with respect to the object, the images exhibit isotropic edge-enhancement. This imaging technique is the first demonstration of a full-field, phase-contrast imaging system with non-local edge enhancement, and enables imaging of phase objects using significantly fewer photons than standard phase-contrast imaging techniques.

  2. Phase-contrast Hounsfield units of fixated and non-fixated soft-tissue samples

    DOE PAGESBeta

    Willner, Marian; Fior, Gabriel; Marschner, Mathias; Birnbacher, Lorenz; Schock, Jonathan; Braun, Christian; Fingerle, Alexander A.; Noël, Peter B.; Rummeny, Ernst J.; Pfeiffer, Franz; et al

    2015-08-31

    X-ray phase-contrast imaging is a novel technology that achieves high soft-tissue contrast. Although its clinical impact is still under investigation, the technique may potentially improve clinical diagnostics. In conventional attenuation-based X-ray computed tomography, radiological diagnostics are quantified by Hounsfield units. Corresponding Hounsfield units for phase-contrast imaging have been recently introduced, enabling a setup-independent comparison and standardized interpretation of imaging results. Thus far, the experimental values of few tissue types have been reported; these values have been determined from fixated tissue samples. This study presents phase-contrast Hounsfield units for various types of non-fixated human soft tissues. A large variety of tissuemore » specimens ranging from adipose, muscle and connective tissues to liver, kidney and pancreas tissues were imaged by a grating interferometer with a rotating-anode X-ray tube and a photon-counting detector. In addition, we investigated the effects of formalin fixation on the quantitative phase-contrast imaging results.« less

  3. Phase-contrast Hounsfield units of fixated and non-fixated soft-tissue samples

    SciTech Connect

    Willner, Marian; Fior, Gabriel; Marschner, Mathias; Birnbacher, Lorenz; Schock, Jonathan; Braun, Christian; Fingerle, Alexander A.; Noël, Peter B.; Rummeny, Ernst J.; Pfeiffer, Franz; Herzen, Julia; Rozhkova, Elena A.

    2015-08-31

    X-ray phase-contrast imaging is a novel technology that achieves high soft-tissue contrast. Although its clinical impact is still under investigation, the technique may potentially improve clinical diagnostics. In conventional attenuation-based X-ray computed tomography, radiological diagnostics are quantified by Hounsfield units. Corresponding Hounsfield units for phase-contrast imaging have been recently introduced, enabling a setup-independent comparison and standardized interpretation of imaging results. Thus far, the experimental values of few tissue types have been reported; these values have been determined from fixated tissue samples. This study presents phase-contrast Hounsfield units for various types of non-fixated human soft tissues. A large variety of tissue specimens ranging from adipose, muscle and connective tissues to liver, kidney and pancreas tissues were imaged by a grating interferometer with a rotating-anode X-ray tube and a photon-counting detector. In addition, we investigated the effects of formalin fixation on the quantitative phase-contrast imaging results.

  4. Phase-contrast X-ray imaging with synchrotron radiation for materials science applications

    NASA Astrophysics Data System (ADS)

    Stevenson, A. W.; Gureyev, T. E.; Paganin, D.; Wilkins, S. W.; Weitkamp, T.; Snigirev, A.; Rau, C.; Snigireva, I.; Youn, H. S.; Dolbnya, I. P.; Yun, W.; Lai, B.; Garrett, R. F.; Cookson, D. J.; Hyodo, K.; Ando, M.

    2003-01-01

    Since Röntgen's discovery of X-rays just over a century ago the vast majority of radiographs have been collected and interpreted on the basis of absorption contrast and geometrical (ray) optics. Recently the possibility of obtaining new and complementary information in X-ray images by utilizing phase-contrast effects has received considerable attention, both in the laboratory context and at synchrotron sources (where much of this activity is a consequence of the highly coherent X-ray beams which can be produced). Phase-contrast X-ray imaging is capable of providing improved information from weakly absorbing features in a sample, together with improved edge definition. Four different experimental arrangements for achieving phase contrast in the hard X-ray regime, for the purpose of non-destructive characterization of materials, will be described. Two of these, demonstrated at ESRF in France and AR in Japan, are based on parallel-beam geometry; the other two, demonstrated at PLS in Korea and APS in USA, are based on spherical-beam geometry. In each case quite different X-ray optical arrangements were used. Some image simulations will be employed to demonstrate salient features of hard X-ray phase-contrast imaging and examples of results from each of the experiments will be shown.

  5. Visualization of water drying in porous materials by X-ray phase contrast imaging.

    PubMed

    Yang, F; Griffa, M; Bonnin, A; Mokso, R; DI Bella, C; Münch, B; Kaufmann, R; Lura, P

    2015-01-01

    We present in this study results from X-ray tomographic microscopy with synchrotron radiation performed both in attenuation and phase contrast modes on a limestone sample during two stages of water drying. No contrast agent was used in order to increase the X-ray attenuation by water. We show that only by using the phase contrast mode it is possible to achieve enough water content change resolution to investigate the drying process at the pore-scale. We performed 3D image analysis of the time-differential phase contrast tomogram. We show by the results of such analysis that it is possible to obtain a reliable characterization of the spatial redistribution of water in the resolved pore system in agreement with what expected from the theory of drying in porous media and from measurements performed with other approaches. We thus show the potential of X-ray phase contrast imaging for pore-scale investigations of reactive water transport processes which cannot be imaged by adding a contrast agent for exploiting the standard attenuation contrast imaging mode. PMID:26469285

  6. Beam hardening effects in grating-based x-ray phase-contrast imaging

    SciTech Connect

    Chabior, Michael; Donath, Tilman; David, Christian; Bunk, Oliver; Schuster, Manfred; Schroer, Christian; Pfeiffer, Franz

    2011-03-15

    Purpose: In this work, the authors investigate how beam hardening affects the image formation in x-ray phase-contrast imaging and consecutively develop a correction algorithm based on the results of the analysis. Methods: The authors' approach utilizes a recently developed x-ray imaging technique using a grating interferometer capable of visualizing the differential phase shift of a wave front traversing an object. An analytical description of beam hardening is given, highlighting differences between attenuation and phase-contrast imaging. The authors present exemplary beam hardening artifacts for a number of well-defined samples in measurements at a compact laboratory setup using a polychromatic source. Results: Despite the differences in image formation, the authors show that beam hardening leads to a similar reduction of image quality in phase-contrast imaging as in conventional attenuation-contrast imaging. Additionally, the authors demonstrate that for homogeneous objects, beam hardening artifacts can be corrected by a linearization technique, applicable to all kinds of phase-contrast methods using polychromatic sources. Conclusions: The evaluated correction algorithm is shown to yield good results for a number of simple test objects and can thus be advocated in medical imaging and nondestructive testing.

  7. In-line phase contrast micro-CT reconstruction for biomedical specimens.

    PubMed

    Fu, Jian; Tan, Renbo

    2014-01-01

    X-ray phase contrast micro computed tomography (micro-CT) can non-destructively provide the internal structure information of soft tissues and low atomic number materials. It has become an invaluable analysis tool for biomedical specimens. Here an in-line phase contrast micro-CT reconstruction technique is reported, which consists of a projection extraction method and the conventional filter back-projection (FBP) reconstruction algorithm. The projection extraction is implemented by applying the Fourier transform to the forward projections of in-line phase contrast micro-CT. This work comprises a numerical study of the method and its experimental verification using a biomedical specimen dataset measured at an X-ray tube source micro-CT setup. The numerical and experimental results demonstrate that the presented technique can improve the imaging contrast of biomedical specimens. It will be of interest for a wide range of in-line phase contrast micro-CT applications in medicine and biology. PMID:24211924

  8. Energy weighting in grating-based X-ray phase-contrast imaging

    NASA Astrophysics Data System (ADS)

    Pelzer, Georg; Weber, Thomas; Anton, Gisela; Ballabriga Sune, Rafael; Bayer, Florian; Campbell, Michael; Haas, Wilhelm; Horn, Florian; Llopart Cudie, Xavi; Michel, Norbert; Mollenbauer, Uwe; Rieger, Jens; Ritter, André; Ritter, Ina; Wölfel, Stefan; Wong, Winnie S.; Zang, Andrea; Michel, Thilo

    2014-03-01

    With energy-resolving photon-counting detectors in grating-based x-ray phase-contrast imaging it is possible to reduce the dose needed and optimize the imaging chain towards better performance. The advantage of photon- counting detector's linear energy response and absence of electronic noise in attenuation based imaging is known. The access to the energy information of the photons counted provides even further potential for optimization by applying energy weighting factors. We have evaluated energy weighting for grating-based phase-contrast imaging. Measurements with the hybrid photon-counting detector Dosepix were performed. The concept of energy binning implemented in the pixel electronics allows individual storing of the energy information of the incoming photons in 16 energy bins for each pixel. With this technique the full spectral information can be obtained pixel wise from one single acquisition. On the differential phase-contrast data taken, we applied different types of energy weighting factors. The results presented in this contribution demonstrate the advantages of energy-resolved photon-counting in differential phase-contrast imaging. Using a x-ray spectrum centred significantly above the interferometers design energy leads to poor image quality. But with the proposed method and detector the quality was enhanced by 2.8 times in signal-to-noise ratio squared. As this is proportional to dose, energy- resolved photon-counting might be valuable especially for medical applications.

  9. Benchmarking the x-ray phase contrast imaging for ICF DT ice characterization using roughened surrogates

    SciTech Connect

    Dewald, E; Kozioziemski, B; Moody, J; Koch, J; Mapoles, E; Montesanti, R; Youngblood, K; Letts, S; Nikroo, A; Sater, J; Atherton, J

    2008-06-26

    We use x-ray phase contrast imaging to characterize the inner surface roughness of DT ice layers in capsules planned for future ignition experiments. It is therefore important to quantify how well the x-ray data correlates with the actual ice roughness. We benchmarked the accuracy of our system using surrogates with fabricated roughness characterized with high precision standard techniques. Cylindrical artifacts with azimuthally uniform sinusoidal perturbations with 100 um period and 1 um amplitude demonstrated 0.02 um accuracy limited by the resolution of the imager and the source size of our phase contrast system. Spherical surrogates with random roughness close to that required for the DT ice for a successful ignition experiment were used to correlate the actual surface roughness to that obtained from the x-ray measurements. When comparing average power spectra of individual measurements, the accuracy mode number limits of the x-ray phase contrast system benchmarked against surface characterization performed by Atomic Force Microscopy are 60 and 90 for surrogates smoother and rougher than the required roughness for the ice. These agreement mode number limits are >100 when comparing matching individual measurements. We will discuss the implications for interpreting DT ice roughness data derived from phase-contrast x-ray imaging.

  10. Refracting Roentgen's rays: Propagation-based x-ray phase contrast for biomedical imaging

    SciTech Connect

    Gureyev, T. E.; Mayo, S. C.; Nesterets, Ya.; Pogany, A.; Stevenson, A. W.; Wilkins, S. W.; Myers, D. E.; Paganin, D. M.

    2009-05-15

    Absorption-contrast x-ray imaging serves to visualize the variation in x-ray attenuation within the volume of a given sample, whereas phase contrast allows one to visualize variations in x-ray refractive index. The former imaging mechanism has been well known and widely utilized since the time of Roentgen's Nobel prize winning work, whereas the latter mechanism--sought for, but not found, by Roentgen himself--has laid the foundation for a revolution in x-ray imaging which is the central topic of this review. We consider the physical imaging mechanisms underlying both absorption contrast and phase contrast, together with the associated inverse problem of how one may obtain quantitative two- or three-dimensional information regarding a sample, given one or more phase-contrast images of the same. Practical questions are considered, regarding optimized phase-contrast imaging geometries as a function of detector resolution, source size, x-ray spectrum, and dose. Experimental examples pertaining to biomedical applications are given, and prospects for the future outlined.

  11. Towards the clinical application of X-ray phase contrast imaging.

    PubMed

    Williams, I M; Siu, K K W; Gan, R; Runxuan, G; He, X; Hart, S A; Styles, C B; Lewis, R A

    2008-12-01

    Synchrotron-based propagation-based imaging, a type of phase contrast imaging, produces better soft tissue image contrast than conventional radiography. To determine whether the technique is directly transferable to the clinical environment for routine diagnostic or screening imaging, a micro-focus (100 microm spot-size) Molybdenum X-ray source with 0.03 mm molybdenum filtration was installed at a local hospital. Breast tissue samples, excised masses and mastectomies, were obtained directly from surgery and imaged at three geometries. The first geometry was optimised for visualizing phase contrast effects using a ray-line argument, the second was the same as that employed by Konica-Minolta in their commercial phase contrast system, and the third was the conventional contact arrangement. The three images taken of each tissue sample were comparatively scored in a pair-wise fashion. Scoring was performed by radiologist expert in mammography, general radiologists, associated clinicians and radiographers on high-resolution mammography rated monitors at two separate locations. Scoring indicated that the optimised and Konica geometries both outperformed the conventional mammographic geometry. An unexpected complication within the trial was the effect that the scoring platform and the associated display tools had on some of the scorer's responses. Additionally, the trial revealed that none of the conventional descriptors for image quality were adequate in the presence of phase contrast enhancements. PMID:18996661

  12. Phase-Contrast Hounsfield Units of Fixated and Non-Fixated Soft-Tissue Samples

    PubMed Central

    Willner, Marian; Fior, Gabriel; Marschner, Mathias; Birnbacher, Lorenz; Schock, Jonathan; Braun, Christian; Fingerle, Alexander A.; Noël, Peter B.; Rummeny, Ernst J.; Pfeiffer, Franz; Herzen, Julia

    2015-01-01

    X-ray phase-contrast imaging is a novel technology that achieves high soft-tissue contrast. Although its clinical impact is still under investigation, the technique may potentially improve clinical diagnostics. In conventional attenuation-based X-ray computed tomography, radiological diagnostics are quantified by Hounsfield units. Corresponding Hounsfield units for phase-contrast imaging have been recently introduced, enabling a setup-independent comparison and standardized interpretation of imaging results. Thus far, the experimental values of few tissue types have been reported; these values have been determined from fixated tissue samples. This study presents phase-contrast Hounsfield units for various types of non-fixated human soft tissues. A large variety of tissue specimens ranging from adipose, muscle and connective tissues to liver, kidney and pancreas tissues were imaged by a grating interferometer with a rotating-anode X-ray tube and a photon-counting detector. Furthermore, we investigated the effects of formalin fixation on the quantitative phase-contrast imaging results. PMID:26322638

  13. Grating-Based Phase-Contrast Imaging of Tumor Angiogenesis in Lung Metastases

    PubMed Central

    Li, Xiangting; Wang, Yujie; Ding, Bei; Shi, Chen; Liu, Huanhuan; Tang, Rongbiao; Sun, Jianqi; Yan, Fuhua; Zhang, Huan

    2015-01-01

    Purpose To assess the feasibility of the grating-based phase-contrast imaging (GPI) technique for studying tumor angiogenesis in nude BALB/c mice, without contrast agents. Methods We established lung metastatic models of human gastric cancer by injecting the moderately differentiated SGC-7901 gastric cancer cell line into the tail vein of nude mice. Samples were embedded in a 10% formalin suspension and dried before imaging. Grating-based X-ray phase-contrast images were obtained at the BL13W beamline of the Shanghai Synchrotron Radiation Facility (SSRF) and compared with histological sections. Results Without contrast agents, grating-based X-ray phase-contrast imaging still differentiated angiogenesis within metastatic tumors with high spatial resolution. Vessels, down to tens of microns, showed gray values that were distinctive from those of the surrounding tumors, which made them easily identifiable. The vessels depicted in the imaging study were similar to those identified on histopathology, both in size and shape. Conclusions Our preliminary study demonstrates that grating-based X-ray phase-contrast imaging has the potential to depict angiogenesis in lung metastases. PMID:25811626

  14. Hard X-Ray Phase-Contrast Imaging for Medical Applications - Physicist's Dream or Radiologist's Mainstream?

    SciTech Connect

    Wilkins, S. W.; Gureyev, T. E.; Mayo, S. C.; Nesterets, Ya. I.; Pogany, A.; Stevenson, A. W.; Paganin, D. M.

    2007-03-30

    We briefly review currently practiced methods of X-ray phase contrast imaging and consider some of their relative features, especially in regard to applicability to clinical medical studies. Various related technological issues and promising future areas of development are also briefly discussed.

  15. Free-Breathing Contrast-Enhanced Multiphase MRI of the Liver Using a Combination of Compressed Sensing, Parallel Imaging, and Golden-Angle Radial Sampling

    PubMed Central

    Chandarana, Hersh; Feng, Li; Block, Tobias K.; Rosenkrantz, Andrew B.; Lim, Ruth P.; Babb, James S.; Sodickson, Daniel K.; Otazo, Ricardo

    2013-01-01

    Objective The objectives of this study were to develop a new method for free-breathing contrast-enhanced multiphase liver magnetic resonance imaging (MRI) using a combination of compressed sensing, parallel imaging, and radial k-space sampling and to demonstrate the feasibility of this method by performing image quality comparison with breath-hold cartesian T1-weighted (conventional) postcontrast acquisitions in healthy participants. Materials and Methods This Health Insurance Portability and Accountability Act–compliant prospective study received approval from the institutional review board. Eight participants underwent 3 separate contrast-enhanced fat-saturated T1-weighted gradient-echo MRI examinations with matching imaging parameters: conventional breath-hold examination with cartesian k-space sampling volumetric interpolate breath hold examination (BH-VIBE) and free-breathing acquisitions with interleaved angle-bisection and continuous golden-angle radial sampling schemes. Interleaved angle-bisection and golden-angle data from each 100 consecutive spokes were reconstructed using a combination of compressed sensing and parallel imaging (interleaved-angle radial sparse parallel [IARASP] and golden-angle radial sparse parallel [GRASP]) to generate multiple postcontrast phases. Arterial- and venous-phase BH-VIBE, IARASP, and GRASP reconstructions were evaluated by 2 radiologists in a blinded fashion. The readers independently assessed quality of enhancement (QE), overall image quality (IQ), and other parameters of image quality on a 5-point scale, with the highest score indicating the most desirable examination. Mixed model analysis of variance was used to compare each measure of image quality. Results Images of BH-VIBE and GRASP had significantly higher QE and IQ values compared with IARASP for both phases (P < 0.05). The differences in QE between BH-VIBE and GRASP for the arterial and venous phases were not significant (P > 0.05). Although GRASP had lower IQ

  16. Evaluation of a new reconstruction algorithm for x-ray phase-contrast imaging

    NASA Astrophysics Data System (ADS)

    Seifert, Maria; Hauke, Christian; Horn, Florian; Lachner, Sebastian; Ludwig, Veronika; Pelzer, Georg; Rieger, Jens; Schuster, Max; Wandner, Johannes; Wolf, Andreas; Michel, Thilo; Anton, Gisela

    2016-04-01

    X-ray grating-based phase-contrast imaging might open up entirely new opportunities in medical imaging. However, transferring the interferometer technique from laboratory setups to conventional imaging systems the necessary rigidity of the system is difficult to achieve. Therefore, vibrations or distortions of the system lead to inaccuracies within the phase-stepping procedure. Given insufficient stability of the phase-step positions, up to now, artifacts in phase-contrast images occur, which lower the image quality. This is a problem with regard to the intended use of phase-contrast imaging in clinical routine as for example tiny structures of the human anatomy cannot be observed. In this contribution we evaluate an algorithm proposed by Vargas et.al.1 and applied to X-ray imaging by Pelzer et.al. that enables us to reconstruct a differential phase-contrast image without the knowledge of the specific phase-step positions. This method was tested in comparison to the standard reconstruction by Fourier analysis. The quality of phase-contrast images remains stable, even if the phase-step positions are completely unknown and not uniformly distributed. To also achieve attenuation and dark-field images the proposed algorithm has been combined with a further algorithm of Vargas et al.3 Using this algorithm, the phase-step positions can be reconstructed. With the help of the proper phase-step positions it is possible to get information about the phase, the amplitude and the offset of the measured data. We evaluated this algorithm concerning the measurement of thick objects which show a high absorbency.

  17. Prospective-gated cardiac micro-CT imaging of free-breathing mice using carbon nanotube field emission x-ray

    SciTech Connect

    Cao Guohua; Burk, Laurel M.; Lee, Yueh Z.; Calderon-Colon, Xiomara; Sultana, Shabana; Lu Jianping; Zhou, Otto

    2010-10-15

    Purpose: Carbon nanotube (CNT) based field emission x-ray source technology has recently been investigated for diagnostic imaging applications because of its attractive characteristics including electronic programmability, fast switching, distributed source, and multiplexing. The purpose of this article is to demonstrate the potential of this technology for high-resolution prospective-gated cardiac micro-CT imaging. Methods: A dynamic cone-beam micro-CT scanner was constructed using a rotating gantry, a stationary mouse bed, a flat-panel detector, and a sealed CNT based microfocus x-ray source. The compact single-beam CNT x-ray source was operated at 50 KVp and 2 mA anode current with 100 {mu}mx100 {mu}m effective focal spot size. Using an intravenously administered iodinated blood-pool contrast agent, prospective cardiac and respiratory-gated micro-CT images of beating mouse hearts were obtained from ten anesthetized free-breathing mice in their natural position. Four-dimensional cardiac images were also obtained by gating the image acquisition to different phases in the cardiac cycle. Results: High-resolution CT images of beating mouse hearts were obtained at 15 ms temporal resolution and 6.2 lp/mm spatial resolution at 10% of system MTF. The images were reconstructed at 76 {mu}m isotropic voxel size. The data acquisition time for two cardiac phases was 44{+-}9 min. The CT values observed within the ventricles and the ventricle wall were 455{+-}49 and 120{+-}48 HU, respectively. The entrance dose for the acquisition of a single phase of the cardiac cycle was 0.10 Gy. Conclusions: A high-resolution dynamic micro-CT scanner was developed from a compact CNT microfocus x-ray source and its feasibility for prospective-gated cardiac micro-CT imaging of free-breathing mice under their natural position was demonstrated.

  18. Multi-pore carbon phase plate for phase-contrast transmission electron microscopy.

    PubMed

    Sannomiya, Takumi; Junesch, Juliane; Hosokawa, Fumio; Nagayama, Kuniaki; Arai, Yoshihiro; Kayama, Yoko

    2014-11-01

    A new fabrication method of carbon based phase plates for phase-contrast transmission electron microscopy is presented. This method utilizes colloidal masks to produce pores as well as disks on thin carbon membranes for phase modulation. Since no serial process is involved, carbon phase plate membranes containing hundreds of pores can be mass-produced on a large scale, which allows "disposal" of contaminated or degraded phase modulating objects after use. Due to the spherical shape of the mask colloid particles, the produced pores are perfectly circular. The pore size and distribution can be easily tuned by the mask colloid size and deposition condition. By using the stencil method, disk type phase plates can also be fabricated on a pore type phase plate. Both pore and disk type phase plates were tested by measuring amorphous samples and confirmed to convert the sinus phase contrast transfer function to the cosine shape. PMID:25129640

  19. An iterative method for robust in-line phase contrast imaging

    NASA Astrophysics Data System (ADS)

    Carroll, Aidan J.; van Riessen, Grant A.; Balaur, Eugeniu; Dolbnya, Igor P.; Tran, Giang N.; Peele, Andrew G.

    2016-04-01

    We present an iterative near-field in-line phase contrast method that allows quantitative determination of the thickness of an object given the refractive index of the sample material. The iterative method allows for quantitative phase contrast imaging in regimes where the contrast transfer function (CTF) and transport of intensity equation (TIE) cannot be applied. Further, the nature of the iterative scheme offers more flexibility and potentially allows more high-resolution image reconstructions when compared to TIE method and less artefacts when compared to the CTF method. While, not addressed here, extension of our approach in future work to broadband illumination will also be straightforward as the wavelength dependence of the refractive index of an object can be readily incorporated into the iterative approach.

  20. Improved algorithm for processing grating-based phase contrast interferometry image sets

    SciTech Connect

    Marathe, Shashidhara Assoufid, Lahsen Xiao, Xianghui; Ham, Kyungmin; Johnson, Warren W.; Butler, Leslie G.

    2014-01-15

    Grating-based X-ray and neutron interferometry tomography using phase-stepping methods generates large data sets. An improved algorithm is presented for solving for the parameters to calculate transmissions, differential phase contrast, and dark-field images. The method takes advantage of the vectorization inherent in high-level languages such as Mathematica and MATLAB and can solve a 16 × 1k × 1k data set in less than a second. In addition, the algorithm can function with partial data sets. This is demonstrated with processing of a 16-step grating data set with partial use of the original data chosen without any restriction. Also, we have calculated the reduced chi-square for the fit and notice the effect of grating support structural elements upon the differential phase contrast image and have explored expanded basis set representations to mitigate the impact.

  1. Enhancing Tabletop X-Ray Phase Contrast Imaging with Nano-Fabrication

    NASA Astrophysics Data System (ADS)

    Miao, Houxun; Gomella, Andrew A.; Harmon, Katherine J.; Bennett, Eric E.; Chedid, Nicholas; Znati, Sami; Panna, Alireza; Foster, Barbara A.; Bhandarkar, Priya; Wen, Han

    2015-08-01

    X-ray phase-contrast imaging is a promising approach for improving soft-tissue contrast and lowering radiation dose in biomedical applications. While current tabletop imaging systems adapt to common x-ray tubes and large-area detectors by employing absorptive elements such as absorption gratings or monolithic crystals to filter the beam, we developed nanometric phase gratings which enable tabletop x-ray far-field interferometry with only phase-shifting elements, leading to a substantial enhancement in the performance of phase contrast imaging. In a general sense the method transfers the demands on the spatial coherence of the x-ray source and the detector resolution to the feature size of x-ray phase masks. We demonstrate its capabilities in hard x-ray imaging experiments at a fraction of clinical dose levels and present comparisons with the existing Talbot-Lau interferometer and with conventional digital radiography.

  2. Propagation-based phase-contrast tomography for high-resolution lung imaging with laboratory sources

    NASA Astrophysics Data System (ADS)

    Krenkel, Martin; Töpperwien, Mareike; Dullin, Christian; Alves, Frauke; Salditt, Tim

    2016-03-01

    We have performed high-resolution phase-contrast tomography on whole mice with a laboratory setup. Enabled by a high-brilliance liquid-metal-jet source, we show the feasibility of propagation-based phase contrast in local tomography even in the presence of strongly absorbing surrounding tissue as it is the case in small animal imaging of the lung. We demonstrate the technique by reconstructions of the mouse lung for two different fields of view, covering the whole organ, and a zoom to the local finer structure of terminal airways and alveoli. With a resolution of a few micrometers and the wide availability of the technique, studies of larger biological samples at the cellular level become possible.

  3. Phase Contrast Cone Beam Tomography with an X-Ray Grating Interferometer

    NASA Astrophysics Data System (ADS)

    Jerjen, I.; Revol, V.; Kottler, C.; Luethi, Th.; Sennhauser, U.; Kaufmann, R.; Urban, C.

    2010-04-01

    We report on our recent developments of reconstruction algorithms for Differential Phase Contrast X-ray Computed Tomography (DPC CT). DPC images provide information about the real and imaginary part of the refractive index which is an advantage when objects with poor absorption but good phase contrast are inspected. In order to promote DPC CT for industrial applications we developed an adapted Feldkamp algorithm which allows reconstructing the three-dimensional image of the refractive index of an object from the DPC projections obtained with our large field of view, high energy grating interferometer set up in a cone beam geometry. We present slice images of a test object and show different ways of visualization of the phase and absorption information.

  4. Development of microperiodic mirrors for hard x-ray phase-contrast imaging

    SciTech Connect

    Stutman, Dan; Finkenthal, Michael; Moldovan, Nicolae

    2010-09-01

    Differential phase-contrast imaging with hard x rays can have important applications in medicine, material sciences, and energy research. Phase-contrast methods based on microperiodic optics, such as shearing interferometry, are particularly attractive because they allow the use of conventional x-ray tubes. To enable shearing interferometry with x rays up to 100 keV, we propose using grazing-incidence microperiodic mirrors. In addition, a simple lithographic method is proposed for the production of the microperiodic x-ray mirrors, based on the difference in grazing-incidence reflectivity between a low-Z substrate and a high-Z film. Using this method, we produced prototype mirrors with 5-100 {mu}m periods and 90 mm active length. Experimental tests with x rays up to 60 keV indicate good microperiodic mirror reflectivity and high-contrast fringe patterns, encouraging further development of the proposed imaging concept.

  5. Sensitivity of edge illumination X-ray phase-contrast imaging

    PubMed Central

    Diemoz, P. C.; Endrizzi, M.; Bravin, A.; Robinson, I. K.; Olivo, A.

    2014-01-01

    Recently, we developed a theoretical model that can predict the signal-to-noise ratio for edge-like features in phase-contrast images. This model was then applied for the estimation of the sensitivity of three different X-ray phase-contrast techniques: propagation-based imaging, analyser-based imaging and grating interferometry. We show here how the same formalism can be used also in the case of the edge illumination (EI) technique, providing results that are consistent with those of a recently developed method for the estimation of noise in the retrieved refraction image. The new model is then applied to calculate, in the case of a given synchrotron radiation set-up, the optimum positions of the pre-sample aperture and detector edge to maximize the sensitivity. Finally, an example of the extremely high angular resolution achievable with the EI technique is presented. PMID:24470420

  6. CO2-based in-line phase contrast imaging of small intestine in mice

    PubMed Central

    Tang, Rongbiao; Li, Wei-Xia; Huang, Wei; Yan, Fuhua; Chai, Wei-Min; Yang, Guo-Yuan; Chen, Ke-Min

    2013-01-01

    The objective of this study was to explore the potential of CO2 single contrast in-line phase contrast imaging (PCI) for pre-clinical small intestine investigation. The absorption and phase contrast images of CO2 gas production were attained and compared. A further increase in image contrast was observed in PCI. Compared with CO2-based absorption contrast imaging (ACI), CO2-based PCI significantly enhanced the detection of mucosal microstructures, such as pits and folds. The CO2-based PCI could provide sufficient image contrast for clearly showing the intestinal mucosa in living mice without using barium. We concluded that CO2-based PCI might be a novel and promising imaging method for future studies of gastrointestinal disorders. PMID:23896957

  7. Enhancing Tabletop X-Ray Phase Contrast Imaging with Nano-Fabrication.

    PubMed

    Miao, Houxun; Gomella, Andrew A; Harmon, Katherine J; Bennett, Eric E; Chedid, Nicholas; Znati, Sami; Panna, Alireza; Foster, Barbara A; Bhandarkar, Priya; Wen, Han

    2015-01-01

    X-ray phase-contrast imaging is a promising approach for improving soft-tissue contrast and lowering radiation dose in biomedical applications. While current tabletop imaging systems adapt to common x-ray tubes and large-area detectors by employing absorptive elements such as absorption gratings or monolithic crystals to filter the beam, we developed nanometric phase gratings which enable tabletop x-ray far-field interferometry with only phase-shifting elements, leading to a substantial enhancement in the performance of phase contrast imaging. In a general sense the method transfers the demands on the spatial coherence of the x-ray source and the detector resolution to the feature size of x-ray phase masks. We demonstrate its capabilities in hard x-ray imaging experiments at a fraction of clinical dose levels and present comparisons with the existing Talbot-Lau interferometer and with conventional digital radiography. PMID:26315891

  8. Characterization of the CCD and CMOS cameras for grating-based phase-contrast tomography

    NASA Astrophysics Data System (ADS)

    Lytaev, Pavel; Hipp, Alexander; Lottermoser, Lars; Herzen, Julia; Greving, Imke; Khokhriakov, Igor; Meyer-Loges, Stephan; Plewka, Jörn; Burmester, Jörg; Caselle, Michele; Vogelgesang, Matthias; Chilingaryan, Suren; Kopmann, Andreas; Balzer, Matthias; Schreyer, Andreas; Beckmann, Felix

    2014-09-01

    In this article we present the quantitative characterization of CCD and CMOS sensors which are used at the experiments for microtomography operated by HZG at PETRA III at DESY in Hamburg, Germany. A standard commercial CCD camera is compared to a camera based on a CMOS sensor. This CMOS camera is modified for grating-based differential phase-contrast tomography. The main goal of the project is to quantify and to optimize the statistical parameters of this camera system. These key performance parameters such as readout noise, conversion gain and full-well capacity are used to define an optimized measurement for grating-based phase-contrast. First results will be shown.

  9. Enhancing Tabletop X-Ray Phase Contrast Imaging with Nano-Fabrication

    PubMed Central

    Miao, Houxun; Gomella, Andrew A.; Harmon, Katherine J.; Bennett, Eric E.; Chedid, Nicholas; Znati, Sami; Panna, Alireza; Foster, Barbara A.; Bhandarkar, Priya; Wen, Han

    2015-01-01

    X-ray phase-contrast imaging is a promising approach for improving soft-tissue contrast and lowering radiation dose in biomedical applications. While current tabletop imaging systems adapt to common x-ray tubes and large-area detectors by employing absorptive elements such as absorption gratings or monolithic crystals to filter the beam, we developed nanometric phase gratings which enable tabletop x-ray far-field interferometry with only phase-shifting elements, leading to a substantial enhancement in the performance of phase contrast imaging. In a general sense the method transfers the demands on the spatial coherence of the x-ray source and the detector resolution to the feature size of x-ray phase masks. We demonstrate its capabilities in hard x-ray imaging experiments at a fraction of clinical dose levels and present comparisons with the existing Talbot-Lau interferometer and with conventional digital radiography. PMID:26315891

  10. Cone-beam differential phase-contrast laminography with x-ray tube source

    NASA Astrophysics Data System (ADS)

    Fu, J.; Biernath, T.; Willner, M.; Amberger, M.; Meiser, J.; Kunka, D.; Mohr, J.; Herzen, J.; Bech, M.; Pfeiffer, F.

    2014-06-01

    We report on an x-ray cone-beam differential phase-contrast computed laminography (DPC-CL) method for tomographic reconstruction of thin and lamellar objects. We describe the specific scan geometry of DPC-CL, which consists of a Talbot-Lau grating interferometer and a lab-based x-ray tube source, and derive a filtered back-projection (FBP) reconstruction algorithm. The experimental results of a flat sphere phantom and a piece of ham demonstrate the validity of the proposed technique. The existing DPC-CL methods are based on synchrotron sources and the parallel-beam geometry. In contrast, our approach adopts a more accessible x-ray tube source and a cone-beam geometry. Therefore it significantly widens the application range of phase-contrast laminography, particularly in practical laboratory settings, beyond applications at large-scale synchrotron facilities.

  11. Improved algorithm for processing grating-based phase contrast interferometry image sets.

    PubMed

    Marathe, Shashidhara; Assoufid, Lahsen; Xiao, Xianghui; Ham, Kyungmin; Johnson, Warren W; Butler, Leslie G

    2014-01-01

    Grating-based X-ray and neutron interferometry tomography using phase-stepping methods generates large data sets. An improved algorithm is presented for solving for the parameters to calculate transmissions, differential phase contrast, and dark-field images. The method takes advantage of the vectorization inherent in high-level languages such as Mathematica and MATLAB and can solve a 16 × 1k × 1k data set in less than a second. In addition, the algorithm can function with partial data sets. This is demonstrated with processing of a 16-step grating data set with partial use of the original data chosen without any restriction. Also, we have calculated the reduced chi-square for the fit and notice the effect of grating support structural elements upon the differential phase contrast image and have explored expanded basis set representations to mitigate the impact. PMID:24517772

  12. CO2-based in-line phase contrast imaging of small intestine in mice

    NASA Astrophysics Data System (ADS)

    Tang, Rongbiao; Li, Wei-Xia; Huang, Wei; Yan, Fuhua; Chai, Wei-Min; Yang, Guo-Yuan; Chen, Ke-Min

    2013-07-01

    The objective of this study was to explore the potential of CO2 single contrast in-line phase contrast imaging (PCI) for pre-clinical small intestine investigation. The absorption and phase contrast images of CO2 gas production were attained and compared. A further increase in image contrast was observed in PCI. Compared with CO2-based absorption contrast imaging (ACI), CO2-based PCI significantly enhanced the detection of mucosal microstructures, such as pits and folds. The CO2-based PCI could provide sufficient image contrast for clearly showing the intestinal mucosa in living mice without using barium. We concluded that CO2-based PCI might be a novel and promising imaging method for future studies of gastrointestinal disorders.

  13. Theoretical analysis of x-ray CT phase-contrast imaging

    NASA Astrophysics Data System (ADS)

    Feng, Sheng; Liu, Song; Zhang, Xuelong

    2008-12-01

    Recently phase contrast imaging has attracted much attention. An obvious advantage of using X-rays for imaging the internal structure of relatively thick samples lies in its high degree of penetration of solid objects. However, often leads to poor image contrast for soft tissue. Phase contrast imaging can be very useful in such situation, as the phase of the transmitted beam may often be more sensitive indicator of density of sample than convention contrast. On the other hand, Computed Tomography is the best technology in the aspect of X-rays detection. Using the technology, the detected object can be imaged to three-dimensional image, so as to observe the inner structure of object, and be convenient to the disease examination. If the phase contrast imaging can be used to the technology of Computed Tomography, the high resolution image can be gained. The technology will become the development orientation of medical image. The aim of this article was to apply the theory of X-rays phase contrast imaging to the traditional X-CT technique. For this purpose, the formula deduced from the imaging theory with parallel monochromatic X-rays illuminating the object based on the Fresnel-Kircohhof theory had been completed and a formula similar to that of the traditional X-CT reconstruction had been gained, which was Radon transform formula. At last, X-rays reconstruction simulation had been carried out according to the formula, and proved that the method could be used in clinical medical imaging. The method discussed in this paper had a very bright prospect for application.

  14. Myelinated mouse nerves studied by X-ray phase contrast zoom tomography.

    PubMed

    Bartels, M; Krenkel, M; Cloetens, P; Möbius, W; Salditt, T

    2015-12-01

    We have used X-ray phase contrast tomography to resolve the structure of uncut, entire myelinated optic, saphenous and sciatic mouse nerves. Intrinsic electron density contrast suffices to identify axonal structures. Specific myelin labeling by an osmium tetroxide stain enables distinction between axon and surrounding myelin sheath. Utilization of spherical wave illumination enables zooming capabilities which enable imaging of entire sciatic internodes as well as identification of sub-structures such as nodes of Ranvier and Schmidt-Lanterman incisures. PMID:26546551

  15. Three-dimensional characterization of electrodeposited lithium microstructures using synchrotron X-ray phase contrast imaging.

    PubMed

    Eastwood, David S; Bayley, Paul M; Chang, Hee Jung; Taiwo, Oluwadamilola O; Vila-Comamala, Joan; Brett, Daniel J L; Rau, Christoph; Withers, Philip J; Shearing, Paul R; Grey, Clare P; Lee, Peter D

    2015-01-01

    The electrodeposition of metallic lithium is a major cause of failure in lithium batteries. The 3D microstructure of electrodeposited lithium 'moss' in liquid electrolytes has been characterised at sub-micron resolution for the first time. Using synchrotron X-ray phase contrast imaging we distinguish mossy metallic lithium microstructures from high surface area lithium salt formations by their contrasting X-ray attenuation. PMID:24898258

  16. X-Ray Grating Interferometry for Phase-Contrast Imaging and Optics Metrology Applications

    NASA Astrophysics Data System (ADS)

    David, Christian; Rutishauser, Simon; Thüring, Thomas; Donath, Tilman; Stampanoni, Marco

    2010-04-01

    We report on a hard x-ray interferometry technique based on diffraction gratings fabricated using microlithography techniques. Compared to other x-ray phase-contrast imaging methods, the grating interferometer only has very moderate requirements in terms of coherence. This makes it possible to use the method with standard x-ray tubes, which opens up a huge range of applications e.g. in medical imaging.

  17. A study of quantification of aortic compliance in mice using radial acquisition phase contrast MRI

    NASA Astrophysics Data System (ADS)

    Zhao, Xuandong

    Spatiotemporal changes in blood flow velocity measured using Phase contrast Magnetic Resonance Imaging (MRI) can be used to quantify Pulse Wave Velocity (PWV) and Wall Shear Stress (WSS), well known indices of vessel compliance. A study was conducted to measure the PWV in the aortic arch in young healthy children using conventional phase contrast MRI and a post processing algorithm that automatically track the peak velocity in phase contrast images. It is shown that the PWV calculated using peak velocity-time data has less variability compared to that using mean velocity and flow. Conventional MR data acquisition techniques lack both the spatial and temporal resolution needed to accurately calculate PWV and WSS in in vivo studies using transgenic animal models of arterial diseases. Radial k-space acquisition can improve both spatial and temporal resolution. A major part of this thesis was devoted to developing technology for Radial Phase Contrast Magnetic Resonance (RPCMR) cine imaging on a 7 Tesla Animal scanner. A pulse sequence with asymmetric radial k-space acquisition was designed and implemented. Software developed to reconstruct the RPCMR images include gridding, density compensation and centering of k-Space that corrects the image ghosting introduced by hardware response time. Image processing software was developed to automatically segment the vessel lumen and correct for phase offset due to eddy currents. Finally, in vivo and ex vivo aortic compliance measurements were conducted in a well-established mouse model for atherosclerosis: Apolipoprotein E-knockout (ApoE-KO). Using RPCMR technique, a significantly higher PWV value as well as a higher average WSS was detected among 9 months old ApoE-KO mice compare to in wild type mice. A follow up ex-vivo test of tissue elasticity confirmed the impaired distensibility of aortic arteries among ApoE-KO mice.

  18. A quantitative, non-interferometric X-ray phase contrast imaging technique

    PubMed Central

    Munro, Peter R.T.; Rigon, Luigi; Ignatyev, Konstantin; Lopez, Frances C.M.; Dreossi, Diego; Speller, Robert D.; Olivo, Alessandro

    2013-01-01

    We present a quantitative, non-interferometric, X-ray differential phase contrast imaging technique based on the edge illumination principle. We derive a novel phase retrieval algorithm which requires only two images to be acquired and verify the technique experimentally using synchrotron radiation. The technique is useful for planar imaging but is expected to be important for quantitative phase tomography also. The properties and limitations of the technique are studied in detail. PMID:23388958

  19. Use of cine phase-contrast MRI in the assessment of distal splenorenal shunt function.

    PubMed

    Cabassa, Paolo; Ravanelli, Marco; Alberti, Daniele; Maroldi, Roberto

    2012-06-01

    Magnetic resonance imaging (MRI) features of a surgical splenorenal shunt in a 28-year-old girl are described. The woman underwent color doppler ultrasonography during follow up for the shunt, which was inconclusive. MR was used to investigate the function of the shunt. Velocity and flow direction in splanchnic vessels and in the shunt were evaluated using cine fast phase-contrast sequences. MR findings could be of help in the evaluation of patients undergoing surgical shunts during follow up. PMID:22405982

  20. Simple broadband implementation of a phase contrast wavefront sensor for adaptive optics

    NASA Technical Reports Server (NTRS)

    Bloemhof, E. E.; Wallace, J. K.

    2004-01-01

    The most critical element of an adaptive optics system is its wavefront sensor, which must measure the closed-loop difference between the corrected wavefront and an ideal template at high speed, in real time, over a dense sampling of the pupil. Most high-order systems have used Shack-Hartmann wavefront sensors, but a novel approach based on Zernike's phase contrast principle appears promising. In this paper we discuss a simple way to achromatize such a phase contrast wavefront sensor, using the pi/2 phase difference between reflected and transmitted rays in a thin, symmetric beam splitter. We further model the response at a range of wavelengths to show that the required transverse dimension of the focal-plane phase-shifting spot, nominally lambda/D, may not be very sensitive to wavelength, and so in practice additional optics to introduce wavelength-dependent transverse magnification achromatizing this spot diameter may not be required. A very simple broadband implementation of the phase contrast wavefront sensor results.

  1. X-ray computed tomography of wood-adhesive bondlines: Attenuation and phase-contrast effects

    SciTech Connect

    Paris, Jesse L.; Kamke, Frederick A.; Xiao, Xianghui

    2015-07-29

    Microscale X-ray computed tomography (XCT) is discussed as a technique for identifying 3D adhesive distribution in wood-adhesive bondlines. Visualization and material segmentation of the adhesives from the surrounding cellular structures require sufficient gray-scale contrast in the reconstructed XCT data. Commercial wood-adhesive polymers have similar chemical characteristics and density to wood cell wall polymers and therefore do not provide good XCT attenuation contrast in their native form. Here, three different adhesive types, namely phenol formaldehyde, polymeric diphenylmethane diisocyanate, and a hybrid polyvinyl acetate, are tagged with iodine such that they yield sufficient X-ray attenuation contrast. However, phase-contrast effects at material edges complicate image quality and segmentation in XCT data reconstructed with conventional filtered backprojection absorption contrast algorithms. A quantitative phase retrieval algorithm, which isolates and removes the phase-contrast effect, was demonstrated. The paper discusses and illustrates the balance between material X-ray attenuation and phase-contrast effects in all quantitative XCT analyses of wood-adhesive bondlines.

  2. Quantitative measurement of ultrasound pressure field by optical phase contrast method and acoustic holography

    NASA Astrophysics Data System (ADS)

    Oyama, Seiji; Yasuda, Jun; Hanayama, Hiroki; Yoshizawa, Shin; Umemura, Shin-ichiro

    2016-07-01

    A fast and accurate measurement of an ultrasound field with various exposure sequences is necessary to ensure the efficacy and safety of various ultrasound applications in medicine. The most common method used to measure an ultrasound pressure field, that is, hydrophone scanning, requires a long scanning time and potentially disturbs the field. This may limit the efficiency of developing applications of ultrasound. In this study, an optical phase contrast method enabling fast and noninterfering measurements is proposed. In this method, the modulated phase of light caused by the focused ultrasound pressure field is measured. Then, a computed tomography (CT) algorithm used to quantitatively reconstruct a three-dimensional (3D) pressure field is applied. For a high-intensity focused ultrasound field, a new approach that combines the optical phase contrast method and acoustic holography was attempted. First, the optical measurement of focused ultrasound was rapidly performed over the field near a transducer. Second, the nonlinear propagation of the measured ultrasound was simulated. The result of the new approach agreed well with that of the measurement using a hydrophone and was improved from that of the phase contrast method alone with phase unwrapping.

  3. Automatic detection of endothelial cells in 3D angiogenic sprouts from experimental phase contrast images

    NASA Astrophysics Data System (ADS)

    Wang, MengMeng; Ong, Lee-Ling Sharon; Dauwels, Justin; Asada, H. Harry

    2015-03-01

    Cell migration studies in 3D environments become more popular, as cell behaviors in 3D are more similar to the behaviors of cells in a living organism (in vivo). We focus on the 3D angiogenic sprouting in microfluidic devices, where Endothelial Cells (ECs) burrow into the gel matrix and form solid lumen vessels. Phase contrast microscopy is used for long-term observation of the unlabeled ECs in the 3D microfluidic devices. Two template matching based approaches are proposed to automatically detect the unlabeled ECs in the angiogenic sprouts from the acquired experimental phase contrast images. Cell and non-cell templates are obtained from these phase contrast images as the training data. The first approach applies Partial Least Square Regression (PLSR) to find the discriminative features and their corresponding weight to distinguish cells and non-cells, whereas the second approach relies on Principal Component Analysis (PCA) to reduce the template feature dimension and Support Vector Machine (SVM) to find their corresponding weight. Through a sliding window manner, the cells in the test images are detected. We then validate the detection accuracy by comparing the results with the same images acquired with a confocal microscope after cells are fixed and their nuclei are stained. More accurate numerical results are obtained for approach I (PLSR) compared to approach II (PCA & SVM) for cell detection. Automatic cell detection will aid in the understanding of cell migration in 3D environment and in turn result in a better understanding of angiogenesis.

  4. A uniqueness result for propagation-based phase contrast imaging from a single measurement

    NASA Astrophysics Data System (ADS)

    Maretzke, Simon

    2015-06-01

    Phase contrast imaging seeks to reconstruct the complex refractive index of an unknown sample from scattering intensities, measured for example under illumination with coherent x-rays. By incorporating refraction, this method yields improved contrast compared to purely absorption-based radiography but involves a phase retrieval problem which, in general, allows for ambiguous reconstructions. In this paper, we show uniqueness of propagation-based phase contrast imaging for compactly supported objects in the near-field regime, based on a description by the projection- and paraxial approximations. In this setting, propagation is governed by the Fresnel propagator and the unscattered part of the illumination function provides a known reference wave at the detector which facilitates phase reconstruction. The uniqueness theorem is derived using the theory of entire functions. Unlike previous results based on exact solution formulae, it is valid for arbitrary complex objects and requires intensity measurements only at a single detector distance and illumination wavelength. We also deduce a uniqueness criterion for phase contrast tomography, which may be applied to resolve the three-dimensional structure of micro- and nano-scale samples. Moreover, our results may have some significance to electronic imaging methods due to the equivalence of paraxial wave propagation and Schrödinger’s equation.

  5. A Broad-Band Phase-Contrast Wave-Front Sensor

    NASA Technical Reports Server (NTRS)

    Bloemhof, Eric; Wallace, J. Kent

    2005-01-01

    A broadband phase-contrast wave-front sensor has been proposed as a real-time wave-front sensor in an adaptive-optics system. The proposed sensor would offer an alternative to the Shack-Hartmann wave-front sensors now used in high-order adaptive-optics systems of some astronomical telescopes. Broadband sensing gives higher sensitivity than does narrow-band sensing, and it appears that for a given bandwidth, the sensitivity of the proposed phase-contrast sensor could exceed that of a Shack-Hartmann sensor. Relative to a Shack-Hartmann sensor, the proposed sensor may be optically and mechanically simpler. As described below, an important element of the principle of operation of a phase-contrast wave-front sensor is the imposition of a 90deg phase shift between diffracted and undiffracted parts of the same light beam. In the proposed sensor, this phase shift would be obtained by utilizing the intrinsic 90 phase shift between the transmitted and reflected beams in an ideal (thin, symmetric) beam splitter. This phase shift can be characterized as achromatic or broadband because it is 90deg at every wavelength over a broad wavelength range.

  6. Performance analysis of quantitative phase retrieval method in Zernike phase contrast X-ray microscopy

    NASA Astrophysics Data System (ADS)

    Heng, Chen; Kun, Gao; Da-Jiang, Wang; Li, Song; Zhi-Li, Wang

    2016-02-01

    Since the invention of Zernike phase contrast method in 1930, it has been widely used in optical microscopy and more recently in X-ray microscopy. Considering the image contrast is a mixture of absorption and phase information, we recently have proposed and demonstrated a method for quantitative phase retrieval in Zernike phase contrast X-ray microscopy. In this contribution, we analyze the performance of this method at different photon energies. Intensity images of PMMA samples are simulated at 2.5 keV and 6.2 keV, respectively, and phase retrieval is performed using the proposed method. The results demonstrate that the proposed phase retrieval method is applicable over a wide energy range. For weakly absorbing features, the optimal photon energy is 2.5 keV, from the point of view of image contrast and accuracy of phase retrieval. On the other hand, in the case of strong absorption objects, a higher photon energy is preferred to reduce the error of phase retrieval. These results can be used as guidelines to perform quantitative phase retrieval in Zernike phase contrast X-ray microscopy with the proposed method. Supported by the State Key Project for Fundamental Research (2012CB825801), National Natural Science Foundation of China (11475170, 11205157 and 11179004) and Anhui Provincial Natural Science Foundation (1508085MA20).

  7. Helical X-ray phase-contrast computed tomography without phase stepping.

    PubMed

    Marschner, M; Willner, M; Potdevin, G; Fehringer, A; Noël, P B; Pfeiffer, F; Herzen, J

    2016-01-01

    X-ray phase-contrast computed tomography (PCCT) using grating interferometry provides enhanced soft-tissue contrast. The possibility to use standard polychromatic laboratory sources enables an implementation into a clinical setting. Thus, PCCT has gained significant attention in recent years. However, phase-contrast CT scans still require significantly increased measurement times in comparison to conventional attenuation-based CT imaging. This is mainly due to a time-consuming stepping of a grating, which is necessary for an accurate retrieval of the phase information. In this paper, we demonstrate a novel scan technique, which directly allows the determination of the phase signal without a phase-stepping procedure. The presented work is based on moiré fringe scanning, which allows fast data acquisition in radiographic applications such as mammography or in-line product analysis. Here, we demonstrate its extension to tomography enabling a continuous helical sample rotation as routinely performed in clinical CT systems. Compared to standard phase-stepping techniques, the proposed helical fringe-scanning procedure enables faster measurements, an extended field of view and relaxes the stability requirements of the system, since the gratings remain stationary. Finally, our approach exceeds previously introduced methods by not relying on spatial interpolation to acquire the phase-contrast signal. PMID:27052368

  8. Contrast enhancement of propagation based X-ray phase contrast imaging

    NASA Astrophysics Data System (ADS)

    Pan, Adam; Xu, Ling; Petruccelli, Jon C.; Gupta, Rajiv; Barbastathis, George

    2014-09-01

    We demonstrate a quantitative X-ray phase contrast imaging (XPCI) technique derived from propagation dependent phase change. We assume that the absorption and phase components are correlated and solve the Transport of Intensity Equation (TIE). The experimental setup is simple compared to other XPCI techniques; the only requirements are a micro-focus X-ray source with sufficient temporal coherence and an X-ray detector of sufficient spatial resolution. This method was demonstrated in three scenarios, the first of which entails identification of an index-matched sphere. A rubber and nylon sphere were immersed in water and imaged. While the rubber sphere could be plainly seen on a radiograph, the nylon sphere was only visible in the phase reconstruction. Next, the technique was applied to differentiating liquid samples. In this scenario, three liquid samples (acetone, water, and hydrogen peroxide) were analyzed using both conventional computed tomography (CT) and phase contrast CT. While conventional CT was capable of differentiating between acetone and the other two liquids, it failed to distinguish between water and hydrogen peroxide; only phase CT was capable of differentiating all three samples. Finally, the technique was applied to CT imaging of a human artery specimen with extensive atherosclerotic plaque. This scenario demonstrated the increased sensitivity to soft tissue compared to conventional CT; it also uncovered some drawbacks of the method, which will be the target of future work. In all cases, the signal-to-noise ratio of phase contrast was greatly enhanced relative to conventional attenuation-based imaging.

  9. Reverse projection retrieval in edge illumination x-ray phase contrast computed tomography

    NASA Astrophysics Data System (ADS)

    Hagen, Charlotte K.; Endrizzi, Marco; Diemoz, Paul C.; Olivo, Alessandro

    2016-06-01

    Edge illumination (EI) x-ray phase contrast computed tomography (CT) can provide three-dimensional distributions of the real and imaginary parts of the complex refractive index (n=1-δ +\\text{i}β ) of the sample. Phase retrieval, i.e. the separation of attenuation and refraction data from projections that contain a combination of both, is a key step in the image reconstruction process. In EI-based x-ray phase contrast CT, this is conventionally performed on the basis of two projections acquired in opposite illumination configurations (i.e. with different positions of the pre-sample mask) at each CT angle. Displacing the pre-sample mask at each projection makes the scan susceptible to motor-induced misalignment and prevents a continuous sample rotation. We present an alternative method for the retrieval of attenuation and refraction data that does not require repositioning the pre-sample mask. The method is based on the reverse projection relation published by Zhu et al (2010 Proc. Natl Acad. Sci. USA 107 13576–81) for grating interferometry-based x-ray phase contrast CT. We use this relation to derive a simplified acquisition strategy that allows acquiring data with a continuous sample rotation, which can reduce scan time when combined with a fast read-out detector. Besides discussing the theory and the necessary alignment of the experimental setup, we present tomograms obtained with reverse projection retrieval and demonstrate their agreement with those obtained with the conventional EI retrieval.

  10. The application of phase contrast X-ray techniques for imaging Li-ion battery electrodes

    NASA Astrophysics Data System (ADS)

    Eastwood, D. S.; Bradley, R. S.; Tariq, F.; Cooper, S. J.; Taiwo, O. O.; Gelb, J.; Merkle, A.; Brett, D. J. L.; Brandon, N. P.; Withers, P. J.; Lee, P. D.; Shearing, P. R.

    2014-04-01

    In order to accelerate the commercialization of fuel cells and batteries across a range of applications, an understanding of the mechanisms by which they age and degrade at the microstructural level is required. Here, the most widely commercialized Li-ion batteries based on porous graphite based electrodes which de/intercalate Li+ ions during charge/discharge are studied by two phase contrast enhanced X-ray imaging modes, namely in-line phase contrast and Zernike phase contrast at the micro (synchrotron) and nano (laboratory X-ray microscope) level, respectively. The rate of charge cycling is directly dependent on the nature of the electrode microstructure, which are typically complex multi-scale 3D geometries with significant microstructural heterogeneities. We have been able to characterise the porosity and the tortuosity by micro-CT as well as the morphology of 5 individual graphite particles by nano-tomography finding that while their volume varied significantly their sphericity was surprisingly similar. The volume specific surface areas of the individual grains measured by nano-CT are significantly larger than the total volume specific surface area of the electrode from the micro-CT imaging, which can be attributed to the greater particle surface area visible at higher resolution.

  11. Quantitative tracking of tumor cells in phase-contrast microscopy exploiting halo artifact pattern

    NASA Astrophysics Data System (ADS)

    Kang, Mi-Sun; Song, Soo-Min; Lee, Hana; Kim, Myoung-Hee

    2012-03-01

    Tumor cell morphology is closely related to its invasiveness characteristics and migratory behaviors. An invasive tumor cell has a highly irregular shape, whereas a spherical cell is non-metastatic. Thus, quantitative analysis of cell features is crucial to determine tumor malignancy or to test the efficacy of anticancer treatment. We use phase-contrast microscopy to analyze single cell morphology and to monitor its change because it enables observation of long-term activity of living cells without photobleaching and phototoxicity, which is common in other fluorescence-labeled microscopy. Despite this advantage, there are image-level drawbacks to phase-contrast microscopy, such as local light effect and contrast interference ring, among others. Thus, we first applied a local filter to compensate for non-uniform illumination. Then, we used intensity distribution information to detect the cell boundary. In phase-contrast microscopy images, the cell normally appears as a dark region surrounded by a bright halo. As the halo artifact around the cell body is minimal and has an asymmetric diffusion pattern, we calculated the cross-sectional plane that intersected the center of each cell and was orthogonal to the first principal axis. Then, we extracted the dark cell region by level set. However, a dense population of cultured cells still rendered single-cell analysis difficult. Finally, we measured roundness and size to classify tumor cells into malignant and benign groups. We validated segmentation accuracy by comparing our findings with manually obtained results.

  12. Helical X-ray phase-contrast computed tomography without phase stepping

    NASA Astrophysics Data System (ADS)

    Marschner, M.; Willner, M.; Potdevin, G.; Fehringer, A.; Noël, P. B.; Pfeiffer, F.; Herzen, J.

    2016-04-01

    X-ray phase-contrast computed tomography (PCCT) using grating interferometry provides enhanced soft-tissue contrast. The possibility to use standard polychromatic laboratory sources enables an implementation into a clinical setting. Thus, PCCT has gained significant attention in recent years. However, phase-contrast CT scans still require significantly increased measurement times in comparison to conventional attenuation-based CT imaging. This is mainly due to a time-consuming stepping of a grating, which is necessary for an accurate retrieval of the phase information. In this paper, we demonstrate a novel scan technique, which directly allows the determination of the phase signal without a phase-stepping procedure. The presented work is based on moiré fringe scanning, which allows fast data acquisition in radiographic applications such as mammography or in-line product analysis. Here, we demonstrate its extension to tomography enabling a continuous helical sample rotation as routinely performed in clinical CT systems. Compared to standard phase-stepping techniques, the proposed helical fringe-scanning procedure enables faster measurements, an extended field of view and relaxes the stability requirements of the system, since the gratings remain stationary. Finally, our approach exceeds previously introduced methods by not relying on spatial interpolation to acquire the phase-contrast signal.

  13. A phase contrast cytomorphometric study of squames of normal oral mucosa and oral leukoplakia: Original study

    PubMed Central

    Nadaf, Afreen; Bavle, Radhika M; Thambiah, Lalita J; Paremala, K; Sudhakara, M; Soumya, M

    2014-01-01

    Oral leukoplakia represents the most common potentially malignant oral disorder, representing 85% of such lesions. The worldwide prevalence of leukoplakia is 1.5- 4.3%. Leukoplakia is often associated with carcinogenic exposures, such as from use of tobacco, alcohol or betel nut. The level of risk for malignant transformation of leukoplakia is associated with lesion histology. The overall malignant transformation rates for dysplastic lesions range from 11% to 36%, depending on the length of follow-up. Exfoliative cytology is a simple and minimally invasive method. Phase contrast microscope, an essential tool in the field of biology and medical research provides improved discrimination of cellular details. Aims: To study and compare the cytomorphological and cytomorphometric features of squames obtained from the mucosa of normal individuals, tobacco habituates with and without clinically evident leukoplakia. To assess the role of phase contrast microscopy as an alternative and easy method of cytological evaluation of wet and unstained smears. Materials and Methods: Fifty cases from each group were taken. Fixed, unstained smears were viewed under phase contrast microscope and were evaluated morphologically and morphometrically for nuclear and cellular diameters. Results: The study showed a significant increase in the mean nuclear diameter and decrease in the mean cellular diameter. Conclusion: Cytomorphometric changes could be the earliest indicators of cellular alterations. This indicates that there could be a cause-effect relationship between tobacco and quantitative alterations. PMID:25364176

  14. High-Resolution and Quantitative X-Ray Phase-Contrast Tomography for Mouse Brain Research

    PubMed Central

    Xi, Yan; Lin, Xiaojie; Yuan, Falei; Yang, Guo-Yuan; Zhao, Jun

    2015-01-01

    Imaging techniques for visualizing cerebral vasculature and distinguishing functional areas are essential and critical to the study of various brain diseases. In this paper, with the X-ray phase-contrast imaging technique, we proposed an experiment scheme for the ex vivo mouse brain study, achieving both high spatial resolution and improved soft-tissue contrast. This scheme includes two steps: sample preparation and volume reconstruction. In the first step, we use heparinized saline to displace the blood inside cerebral vessels and then replace it with air making air-filled mouse brain. After sample preparation, X-ray phase-contrast tomography is performed to collect the data for volume reconstruction. Here, we adopt a phase-retrieval combined filtered backprojection method to reconstruct its three-dimensional structure and redesigned the reconstruction kernel. To evaluate its performance, we carried out experiments at Shanghai Synchrotron Radiation Facility. The results show that the air-tissue structured cerebral vasculatures are highly visible with propagation-based phase-contrast imaging and can be clearly resolved in reconstructed cross-images. Besides, functional areas, such as the corpus callosum, corpus striatum, and nuclei, are also clearly resolved. The proposed method is comparable with hematoxylin and eosin staining method but represents the studied mouse brain in three dimensions, offering a potential powerful tool for the research of brain disorders. PMID:26576198

  15. Experimental results from a preclinical X-ray phase-contrast CT scanner

    PubMed Central

    Tapfer, Arne; Bech, Martin; Velroyen, Astrid; Meiser, Jan; Mohr, Jürgen; Walter, Marco; Schulz, Joachim; Pauwels, Bart; Bruyndonckx, Peter; Liu, Xuan; Sasov, Alexander; Pfeiffer, Franz

    2012-01-01

    To explore the future clinical potential of improved soft-tissue visibility with grating-based X-ray phase contrast (PC), we have developed a first preclinical computed tomography (CT) scanner featuring a rotating gantry. The main challenge in the transition from previous bench-top systems to a preclinical scanner are phase artifacts that are caused by minimal changes in the grating alignment during gantry rotation. In this paper, we present the first experimental results from the system together with an adaptive phase recovery method that corrects for these phase artifacts. Using this method, we show that the scanner can recover quantitatively accurate Hounsfield units in attenuation and phase. Moreover, we present a first tomography scan of biological tissue with complementary information in attenuation and phase contrast. The present study hence demonstrates the feasibility of grating-based phase contrast with a rotating gantry for the first time and paves the way for future in vivo studies on small animal disease models (in the mid-term future) and human diagnostics applications (in the long-term future). PMID:23019354

  16. Helical X-ray phase-contrast computed tomography without phase stepping

    PubMed Central

    Marschner, M.; Willner, M.; Potdevin, G.; Fehringer, A.; Noël, P. B.; Pfeiffer, F.; Herzen, J.

    2016-01-01

    X-ray phase-contrast computed tomography (PCCT) using grating interferometry provides enhanced soft-tissue contrast. The possibility to use standard polychromatic laboratory sources enables an implementation into a clinical setting. Thus, PCCT has gained significant attention in recent years. However, phase-contrast CT scans still require significantly increased measurement times in comparison to conventional attenuation-based CT imaging. This is mainly due to a time-consuming stepping of a grating, which is necessary for an accurate retrieval of the phase information. In this paper, we demonstrate a novel scan technique, which directly allows the determination of the phase signal without a phase-stepping procedure. The presented work is based on moiré fringe scanning, which allows fast data acquisition in radiographic applications such as mammography or in-line product analysis. Here, we demonstrate its extension to tomography enabling a continuous helical sample rotation as routinely performed in clinical CT systems. Compared to standard phase-stepping techniques, the proposed helical fringe-scanning procedure enables faster measurements, an extended field of view and relaxes the stability requirements of the system, since the gratings remain stationary. Finally, our approach exceeds previously introduced methods by not relying on spatial interpolation to acquire the phase-contrast signal. PMID:27052368

  17. Phase contrast imaging using a micro focus x-ray source

    NASA Astrophysics Data System (ADS)

    Zhou, Wei; Majidi, Keivan; Brankov, Jovan G.

    2014-09-01

    Phase contrast x-ray imaging, a new technique to increase the imaging contrast for the tissues with close attenuation coefficients, has been studied since mid 1990s. This technique reveals the possibility to show the clear details of the soft tissues and tumors in small scale resolution. A compact and low cost phase contrast imaging system using a conventional x-ray source is described in this paper. Using the conventional x-ray source is of great importance, because it provides the possibility to use the method in hospitals and clinical offices. Simple materials and components are used in the setup to keep the cost in a reasonable and affordable range.Tungsten Kα1 line with the photon energy 59.3 keV was used for imaging. Some of the system design details are discussed. The method that was used to stabilize the system is introduced. A chicken thigh bone tissue sample was used for imaging followed by the image quality, image acquisition time and the potential clinical application discussion. High energy x-ray beam can be used in phase contrast imaging. Therefore the radiation dose to the patients can be greatly decreased compared to the traditional x-ray radiography.

  18. X-ray computed tomography of wood-adhesive bondlines: Attenuation and phase-contrast effects

    DOE PAGESBeta

    Paris, Jesse L.; Kamke, Frederick A.; Xiao, Xianghui

    2015-07-29

    Microscale X-ray computed tomography (XCT) is discussed as a technique for identifying 3D adhesive distribution in wood-adhesive bondlines. Visualization and material segmentation of the adhesives from the surrounding cellular structures require sufficient gray-scale contrast in the reconstructed XCT data. Commercial wood-adhesive polymers have similar chemical characteristics and density to wood cell wall polymers and therefore do not provide good XCT attenuation contrast in their native form. Here, three different adhesive types, namely phenol formaldehyde, polymeric diphenylmethane diisocyanate, and a hybrid polyvinyl acetate, are tagged with iodine such that they yield sufficient X-ray attenuation contrast. However, phase-contrast effects at material edgesmore » complicate image quality and segmentation in XCT data reconstructed with conventional filtered backprojection absorption contrast algorithms. A quantitative phase retrieval algorithm, which isolates and removes the phase-contrast effect, was demonstrated. The paper discusses and illustrates the balance between material X-ray attenuation and phase-contrast effects in all quantitative XCT analyses of wood-adhesive bondlines.« less

  19. Phase-contrast x-ray imaging of the breast: recent developments towards clinics

    NASA Astrophysics Data System (ADS)

    Coan, P.; Bravin, A.; Tromba, G.

    2013-12-01

    Breast imaging is one of the most demanding and delicate radiological applications. Mammography is the primary diagnosis tool in breast cancer detection and national screening programmes. Recognition of breast cancer depends on the detection of subtle architectural distortion, masses showing near normal breast tissue density, skin thickening and microcalcifications. The small differences in attenuation of x-rays between normal and malignant tissue result in low contrast and make cancer detection difficult in conventional x-ray absorption mammography. Because of these challenging aspects, breast imaging has been the first and most explored diagnostic field in phase-contrast imaging research. This novel imaging method has been extensively used and has demonstrated a unique capability in producing high-contrast and sensitive images at quasi-histological resolution. The most recent and significant technical developments are introduced and results obtained by the application of various phase-contrast imaging techniques for breast imaging are reported. The first phase-contrast mammography clinical trials project is also presented and the short- and long-term future perspectives of the method are discussed.

  20. High-energy x-ray grating-based phase-contrast radiography of human anatomy

    NASA Astrophysics Data System (ADS)

    Horn, Florian; Hauke, Christian; Lachner, Sebastian; Ludwig, Veronika; Pelzer, Georg; Rieger, Jens; Schuster, Max; Seifert, Maria; Wandner, Johannes; Wolf, Andreas; Michel, Thilo; Anton, Gisela

    2016-03-01

    X-ray grating-based phase-contrast Talbot-Lau interferometry is a promising imaging technology that has the potential to raise soft tissue contrast in comparison to conventional attenuation-based imaging. Additionally, it is sensitive to attenuation, refraction and scattering of the radiation and thus provides complementary and otherwise inaccessible information due to the dark-field image, which shows the sub-pixel size granularity of the measured object. Until recent progress the method has been mainly limited to photon energies below 40 keV. Scaling the method to photon energies that are sufficient to pass large and spacious objects represents a challenging task. This is caused by increasing demands regarding the fabrication process of the gratings and the broad spectra that come along with the use of polychromatic X-ray sources operated at high acceleration voltages. We designed a setup that is capable to reach high visibilities in the range from 50 to 120 kV. Therefore, spacious and dense parts of the human body with high attenuation can be measured, such as a human knee. The authors will show investigations on the resulting attenuation, differential phase-contrast and dark-field images. The images experimentally show that X-ray grating-based phase-contrast radiography is feasible with highly absorbing parts of the human body containing massive bones.

  1. Phantom study based on a high-energy in-line phase contrast tomosynthesis prototype

    NASA Astrophysics Data System (ADS)

    Wu, Di; Yan, Aimin; Li, Yuhua; Chen, Wei R.; Wu, Xizeng; Liu, Hong

    2014-02-01

    The objective of this research is to demonstrate an in-line phase contrast tomosynthesis prototype operated under high x-ray tube voltage, and a phantom study was conducted to characterize the potentials of this system. The prototype is based on an in-line phase contrast system accompanying with digital tomosynthesis imaging mechanism; and the tube voltage is operated at 120 kVp. A phantom study was conducted by using a custom-designed fish bone phantom to demonstrate the ability of this imaging system in edge enhancement and noise suppression. As the result, edge enhancement could be observed on the in-plane slices by plotting and comparing the intensity profiles with DTS images. As employing phase retrieval method onto the original angular projections could dramatically improve the image quality in edge enhancement, 3D imaging box was preliminarily constructed by using reconstructed in-plane slices acquired with PAD phase retrieval. As expected, high-energy in-line phase contrast tomosynthesis imaging system shows its potentials in edge enhancement and noise suppression by introducing phase retrieval method. Dose studies and perfecting photon energies and phantom designs will be our future interest.

  2. Differential phase contrast with a segmented detector in a scanning X-ray microprobe

    PubMed Central

    Hornberger, B.; de Jonge, M. D.; Feser, M.; Holl, P.; Holzner, C.; Jacobsen, C.; Legnini, D.; Paterson, D.; Rehak, P.; Strüder, L.; Vogt, S.

    2008-01-01

    Scanning X-ray microprobes are unique tools for the nanoscale investigation of specimens from the life, environmental, materials and other fields of sciences. Typically they utilize absorption and fluorescence as contrast mechanisms. Phase contrast is a complementary technique that can provide strong contrast with reduced radiation dose for weakly absorbing structures in the multi-keV range. In this paper the development of a segmented charge-integrating silicon detector which provides simultaneous absorption and differential phase contrast is reported. The detector can be used together with a fluorescence detector for the simultaneous acquisition of transmission and fluorescence data. It can be used over a wide range of photon energies, photon rates and exposure times at third-generation synchrotron radiation sources, and is currently operating at two beamlines at the Advanced Photon Source. Images obtained at around 2 keV and 10 keV demonstrate the superiority of phase contrast over absorption for specimens composed of light elements. PMID:18552427

  3. Abdominal sounds

    MedlinePlus

    ... during sleep. They also occur normally for a short time after the use of certain medicines and after abdominal surgery. Decreased or absent bowel sounds often indicate constipation. Increased ( hyperactive ) bowel sounds ...

  4. Abdominal MRI

    MedlinePlus

    ... provider if you have: Artificial heart valves Brain aneurysm clips Heart defibrillator or pacemaker Inner ear (cochlear) ... which the test may be performed: Abdominal aortic aneurysm Atheroembolic renal disease Carcinoma of the renal pelvis ...

  5. Abdominal pain

    MedlinePlus

    ... threatening conditions, such as colon cancer or early appendicitis , may only cause mild pain or no pain. ... Food poisoning Stomach flu Other possible causes include: Appendicitis Abdominal aortic aneurysm (bulging and weakening of the ...

  6. Abdominal Pain

    MedlinePlus

    ... can help the overall situation for the child. Teaching kids self-hypnosis [8] or guided imagery [8a] ... related topics? Functional Abdominal Pain (English, French or Spanish)—from The North American Society for Pediatric Gastroenterology, ...

  7. Grating-based phase contrast tomosynthesis imaging: Proof-of-concept experimental studies

    SciTech Connect

    Li, Ke; Ge, Yongshuai; Garrett, John; Bevins, Nicholas; Zambelli, Joseph; Chen, Guang-Hong

    2014-01-15

    Purpose: This paper concerns the feasibility of x-ray differential phase contrast (DPC) tomosynthesis imaging using a grating-based DPC benchtop experimental system, which is equipped with a commercial digital flat-panel detector and a medical-grade rotating-anode x-ray tube. An extensive system characterization was performed to quantify its imaging performance. Methods: The major components of the benchtop system include a diagnostic x-ray tube with a 1.0 mm nominal focal spot size, a flat-panel detector with 96 μm pixel pitch, a sample stage that rotates within a limited angular span of ±30°, and a Talbot-Lau interferometer with three x-ray gratings. A total of 21 projection views acquired with 3° increments were used to reconstruct three sets of tomosynthetic image volumes, including the conventional absorption contrast tomosynthesis image volume (AC-tomo) reconstructed using the filtered-backprojection (FBP) algorithm with the ramp kernel, the phase contrast tomosynthesis image volume (PC-tomo) reconstructed using FBP with a Hilbert kernel, and the differential phase contrast tomosynthesis image volume (DPC-tomo) reconstructed using the shift-and-add algorithm. Three inhouse physical phantoms containing tissue-surrogate materials were used to characterize the signal linearity, the signal difference-to-noise ratio (SDNR), the three-dimensional noise power spectrum (3D NPS), and the through-plane artifact spread function (ASF). Results: While DPC-tomo highlights edges and interfaces in the image object, PC-tomo removes the differential nature of the DPC projection data and its pixel values are linearly related to the decrement of the real part of the x-ray refractive index. The SDNR values of polyoxymethylene in water and polystyrene in oil are 1.5 and 1.0, respectively, in AC-tomo, and the values were improved to 3.0 and 2.0, respectively, in PC-tomo. PC-tomo and AC-tomo demonstrate equivalent ASF, but their noise characteristics quantified by the 3D NPS

  8. Simultaneous amplitude-contrast and phase-contrast surface plasmon resonance imaging by use of digital holography

    PubMed Central

    Li, Shiping; Zhong, Jingang

    2012-01-01

    The surface plasmon resonance imaging technique provides a tool that allows high-throughput analysis and real-time kinetic measurement. A simultaneous amplitude-contrast and phase-contrast surface plasmon resonance imaging method is presented. The amplitude-contrast and phase-contrast images are simultaneously obtained by use of digital holography. The detection sensitivity of amplitude-contrast imaging and phase-contrast imaging can compensate for each other. Thus, the detectable sample components may cover a wider range of refractive index values for the simultaneous amplitude-contrast and phase-contrast imaging method than for the phase-contrast imaging method or amplitude-contrast imaging method. A detailed description of the theory and an experiment of monitoring the evaporation process of a drop of NaCl injection in real time are presented. In addition, the amplitude-contrast image has less coherent noise by digital holography. PMID:23243569

  9. The effect of respiratory cycle and radiation beam-on timing on the dose distribution of free-breathing breast treatment using dynamic IMRT

    SciTech Connect

    Ding Chuxiong; Li Xiang; Huq, M. Saiful; Saw, Cheng B.; Heron, Dwight E.; Yue, Ning J.

    2007-09-15

    In breast cancer treatment, intensity-modulated radiation therapy (IMRT) can be utilized to deliver more homogeneous dose to target tissues to minimize the cosmetic impact. We have investigated the effect of the respiratory cycle and radiation beam-on timing on the dose distribution in free-breathing dynamic breast IMRT treatment. Six patients with early stage cancer of the left breast were included in this study. A helical computed tomography (CT) scan was acquired for treatment planning. A four-dimensional computed tomography (4D CT) scan was obtained right after the helical CT scan with little or no setup uncertainty to simulate patient respiratory motion. After optimizing based on the helical CT scan, the sliding-window dynamic multileaf collimator (DMLC) leaf sequence was segmented into multiple sections that corresponded to various respiratory phases per respiratory cycle and radiation beam-on timing. The segmented DMLC leaf sections were grouped according to respiratory phases and superimposed over the radiation fields of corresponding 4D CT image set. Dose calculation was then performed for each phase of the 4D CT scan. The total dose distribution was computed by accumulating the contribution of dose from each phase to every voxel in the region of interest. This was tracked by a deformable registration program throughout all of the respiratory phases of the 4D CT scan. A dose heterogeneity index, defined as the ratio between (D{sub 20}-D{sub 80}) and the prescription dose, was introduced to numerically illustrate the impact of respiratory motion on the dose distribution of treatment volume. A respiratory cycle range of 4-8 s and randomly distributed beam-on timing were assigned to simulate the patient respiratory motion during the free-breathing treatment. The results showed that the respiratory cycle period and radiation beam-on timing presented limited impact on the target dose coverage and slightly increased the target dose heterogeneity. This motion

  10. SU-E-T-426: Dose Delivery Accuracy in Breast Field Junction for Free Breath and Deep Inspiration Breath Hold Techniques

    SciTech Connect

    Epstein, D; Shekel, E; Levin, D

    2014-06-01

    Purpose: The purpose of this work was to verify the accuracy of the dose distribution along the field junction in a half beam irradiation technique for breast cancer patients receiving radiation to the breast or chest wall (CW) and the supraclavicular LN region for both free breathing and deep inspiration breath hold (DIBH) technique. Methods: We performed in vivo measurements for nine breast cancer patients receiving radiation to the breast/CW and to the supraclavicular LN region. Six patients were treated to the left breast/CW using DIBH technique and three patients were treated to the right breast/CW in free breath. We used five microMOSFET dosimeters: three located along the field junction, one located 1 cm above the junction and the fifth microMOSFET located 1 cm below the junction. We performed consecutive measurements over several days for each patient and compared the measurements to the TPS calculation (Eclipse, Varian™). Results: The calculated and measured doses along the junction were 0.97±0.08 Gy and 1.02±0.14 Gy, respectively. Above the junction calculated and measured doses were 0.91±0.08 Gy and 0.98±0.09 Gy respectively, and below the junction calculated and measured doses were 1.70±0.15 Gy and 1.61±0.09 Gy, respectively. All differences were not statistically significant. When comparing calculated and measured doses for DIBH patients only, there was still no statistically significant difference between values for all dosimeter locations. Analysis was done using the Mann-Whitney Rank-Sum Test. Conclusion: We found excellent correlation between calculated doses from the TPS and measured skin doses at the junction of several half beam fields. Even for the DIBH technique, where there is more potential for variance due to depth of breath, there is no over or underdose along the field junction. This correlation validates the TPS, as well an accurate, reproducible patient setup.

  11. Contrast-to-noise ratio optimization for a prototype phase-contrast computed tomography scanner

    SciTech Connect

    Müller, Mark Yaroshenko, Andre; Velroyen, Astrid; Tapfer, Arne; Bech, Martin; Pauwels, Bart; Bruyndonckx, Peter; Sasov, Alexander; Pfeiffer, Franz

    2015-12-15

    In the field of biomedical X-ray imaging, novel techniques, such as phase-contrast and dark-field imaging, have the potential to enhance the contrast and provide complementary structural information about a specimen. In this paper, a first prototype of a preclinical X-ray phase-contrast CT scanner based on a Talbot-Lau interferometer is characterized. We present a study of the contrast-to-noise ratios for attenuation and phase-contrast images acquired with the prototype scanner. The shown results are based on a series of projection images and tomographic data sets of a plastic phantom in phase and attenuation-contrast recorded with varying acquisition settings. Subsequently, the signal and noise distribution of different regions in the phantom were determined. We present a novel method for estimation of contrast-to-noise ratios for projection images based on the cylindrical geometry of the phantom. Analytical functions, representing the expected signal in phase and attenuation-contrast for a circular object, are fitted to individual line profiles of the projection data. The free parameter of the fit function is used to estimate the contrast and the goodness of the fit is determined to assess the noise in the respective signal. The results depict the dependence of the contrast-to-noise ratios on the applied source voltages, the number of steps of the phase stepping routine, and the exposure times for an individual step. Moreover, the influence of the number of projection angles on the image quality of CT slices is investigated. Finally, the implications for future imaging purposes with the scanner are discussed.

  12. Quantitative analysis of contrast to noise ratio using a phase contrast x-ray imaging prototype

    NASA Astrophysics Data System (ADS)

    Ghani, Muhammad U.; Wu, Di; Li, Yuhua; Kang, Minhua; Chen, Wei R.; Wu, Xizeng; Liu, Hong

    2013-02-01

    The purpose of this study was to determine the Contrast to Noise Ratio (CNR) of the x-ray images taken with the phase contrast imaging mode and compare them with the CNR of the images taken under the conventional mode. For each mode, three images were taken under three exposure conditions of 100 kVp (2.8mAs), 120 kVp (1.9mAs) and 140kVp (1.42mAs). A 1.61cm thick contrast detail phantom was used as an imaging object. For phase contrast, the source to image detector distance (SID) was 182.88 cm and the source to object (SOD) distance was 73.15 cm. The SOD was the same as SID in the conventional imaging mode. A computed radiography (CR) plate was used as a detector and the output CR images were converted to linear form in relation with the incident x-ray exposure. To calculate CNR, an image processing software was used to determine the mean pixel value and the standard deviation of the pixels in the region of interest (ROI) and in the nearby background around ROI. At any given exposure condition investigated in this study, the CNR values for the phase contrast images were better as compared to the corresponding conventional mode images. The superior image quality in terms of CNR is contributed by the phase-shifts resulted contrast, as well as the reduced scatters due to the air gap between the object and the detector.

  13. Contrast-to-noise ratio optimization for a prototype phase-contrast computed tomography scanner.

    PubMed

    Müller, Mark; Yaroshenko, Andre; Velroyen, Astrid; Bech, Martin; Tapfer, Arne; Pauwels, Bart; Bruyndonckx, Peter; Sasov, Alexander; Pfeiffer, Franz

    2015-12-01

    In the field of biomedical X-ray imaging, novel techniques, such as phase-contrast and dark-field imaging, have the potential to enhance the contrast and provide complementary structural information about a specimen. In this paper, a first prototype of a preclinical X-ray phase-contrast CT scanner based on a Talbot-Lau interferometer is characterized. We present a study of the contrast-to-noise ratios for attenuation and phase-contrast images acquired with the prototype scanner. The shown results are based on a series of projection images and tomographic data sets of a plastic phantom in phase and attenuation-contrast recorded with varying acquisition settings. Subsequently, the signal and noise distribution of different regions in the phantom were determined. We present a novel method for estimation of contrast-to-noise ratios for projection images based on the cylindrical geometry of the phantom. Analytical functions, representing the expected signal in phase and attenuation-contrast for a circular object, are fitted to individual line profiles of the projection data. The free parameter of the fit function is used to estimate the contrast and the goodness of the fit is determined to assess the noise in the respective signal. The results depict the dependence of the contrast-to-noise ratios on the applied source voltages, the number of steps of the phase stepping routine, and the exposure times for an individual step. Moreover, the influence of the number of projection angles on the image quality of CT slices is investigated. Finally, the implications for future imaging purposes with the scanner are discussed. PMID:26724040

  14. Contrast-to-noise ratio optimization for a prototype phase-contrast computed tomography scanner

    NASA Astrophysics Data System (ADS)

    Müller, Mark; Yaroshenko, Andre; Velroyen, Astrid; Bech, Martin; Tapfer, Arne; Pauwels, Bart; Bruyndonckx, Peter; Sasov, Alexander; Pfeiffer, Franz

    2015-12-01

    In the field of biomedical X-ray imaging, novel techniques, such as phase-contrast and dark-field imaging, have the potential to enhance the contrast and provide complementary structural information about a specimen. In this paper, a first prototype of a preclinical X-ray phase-contrast CT scanner based on a Talbot-Lau interferometer is characterized. We present a study of the contrast-to-noise ratios for attenuation and phase-contrast images acquired with the prototype scanner. The shown results are based on a series of projection images and tomographic data sets of a plastic phantom in phase and attenuation-contrast recorded with varying acquisition settings. Subsequently, the signal and noise distribution of different regions in the phantom were determined. We present a novel method for estimation of contrast-to-noise ratios for projection images based on the cylindrical geometry of the phantom. Analytical functions, representing the expected signal in phase and attenuation-contrast for a circular object, are fitted to individual line profiles of the projection data. The free parameter of the fit function is used to estimate the contrast and the goodness of the fit is determined to assess the noise in the respective signal. The results depict the dependence of the contrast-to-noise ratios on the applied source voltages, the number of steps of the phase stepping routine, and the exposure times for an individual step. Moreover, the influence of the number of projection angles on the image quality of CT slices is investigated. Finally, the implications for future imaging purposes with the scanner are discussed.

  15. On detector linearity and precision of beam shift detection for quantitative differential phase contrast applications.

    PubMed

    Zweck, Josef; Schwarzhuber, Felix; Wild, Johannes; Galioit, Vincent

    2016-09-01

    Differential phase contrast is a STEM imaging mode where minute sideways deflections of the electron probe are monitored, usually by using a position sensitive device (Chapman, 1984 [1]; Lohr et al., 2012 [2]) or, alternatively in some cases, a fast camera (Müller et al., 2012 [3,4]; Yang et al., 2015 [5]; Pennycook et al., 2015 [6]) as a pixelated detector. While traditionally differential phase contrast electron microscopy was mainly focused on investigations of micro-magnetic domain structures and their specific features, such as domain wall widths, etc. (Chapman, 1984 [1]; Chapman et al., 1978, 1981, 1985 [7-9]; Sannomiya et al., 2004 [10]), its usage has recently been extended to mesoscopic (Lohr et al., 2012, 2016 [2,12]; Bauer et al., 2014 [11]; Shibata et al., 2015 [13]) and nano-scale electric fields (Shibata et al., 2012 [14]; Mueller et al., 2014 [15]). In this paper, the various interactions which can cause a beam deflection are reviewed and expanded by two so far undiscussed mechanisms which may be important for biological applications. As differential phase contrast microscopy strongly depends on the ability to detect minute beam deflections we first treat the linearity problem for an annular four quadrant detector and then determine the factors which limit the minimum measurable deflection angle, such as S/N ratio, current density, dwell time and detector geometry. Knowing these factors enables the experimenter to optimize the set-up for optimum performance of the microscope and to get a clear figure for the achievable field resolution error margins. PMID:27376783

  16. Abdominal Sepsis.

    PubMed

    De Waele, Jan J

    2016-08-01

    Abdominal infections are an important challenge for the intensive care physician. In an era of increasing antimicrobial resistance, selecting the appropriate regimen is important and, with new drugs coming to the market, correct use is important more than ever before and abdominal infections are an excellent target for antimicrobial stewardship programs. Biomarkers may be helpful, but their exact role in managing abdominal infections remains incompletely understood. Source control also remains an ongoing conundrum, and evidence is increasing that its importance supersedes the impact of antibiotic therapy. New strategies such as open abdomen management may offer added benefit in severely ill patients, but more data are needed to identify its exact role. The role of fungi and the need for antifungal coverage, on the other hand, have been investigated extensively in recent years, but at this point, it remains unclear who requires empirical as well as directed therapy. PMID:27363829

  17. Ultrafast, high resolution, phase contrast imaging of impact response with synchrotron radiation

    SciTech Connect

    Jensen, B. J.; Luo, S. N.; Hooks, D. E.; Ramos, K. J.; Yeager, J. D.; Kwiatkowski, K.; Shimada, T.; Dattelbaum, D. M.; Fezzaa, K.

    2012-03-15

    Understanding the dynamic response of materials at extreme conditions requires diagnostics that can provide real-time, in situ, spatially resolved measurements on the nanosecond timescale. The development of methods such as phase contrast imaging (PCI) typically used at synchrotron sources offer unique opportunities to examine dynamic material response. In this work, we report ultrafast, high-resolution, dynamic PCI measurements of shock compressed materials with 3 {mu}m spatial resolution using a single 60 ps synchrotron X-ray bunch. These results firmly establish the use of PCI to examine dynamic phenomena at ns to {mu}s timescales.

  18. A coded-aperture technique allowing x-ray phase contrast imaging with conventional sources

    SciTech Connect

    Olivo, Alessandro; Speller, Robert

    2007-08-13

    Phase contrast imaging (PCI) solves the basic limitation of x-ray imaging, i.e., poor image contrast resulting from small absorption differences. Up to now, it has been mostly limited to synchrotron radiation facilities, due to the stringent requirements on the x-ray source and detectors, and only one technique was shown to provide PCI images with conventional sources but with limits in practical implementation. The authors propose a different approach, based on coded apertures, which provides high PCI signals with conventional sources and detectors and imposes practically no applicability limits. They expect this method to cast the basis of a widespread diffusion of PCI.

  19. Optimization Of Phase-Contrast Enhanced X-Ray Imaging Of D-T Layers

    SciTech Connect

    Kozioziemski, B

    2005-06-17

    Phase-contrast enhanced x-ray imaging has been demonstrated for characterization of D-T layers inside of beryllium shells. These first demonstrations used both scintillator and direct-detection imaging. This memo details tradeoffs between the two methods in order to optimize the imaging. The guiding principle for optimization is to minimize the exposure time while maximizing the signal-to-noise ratio at the D-T solid-vapor interface. Direct-detection and scintillator performance are comparable when imaging the full capsule. However, a scintillator allows for higher-resolution images necessary for studying local defects in the D-T layer.

  20. Fast gridding projectors for analytical and iterative tomographic reconstruction of differential phase contrast data.

    PubMed

    Arcadu, Filippo; Stampanoni, Marco; Marone, Federica

    2016-06-27

    This paper introduces new gridding projectors designed to efficiently perform analytical and iterative tomographic reconstruction, when the forward model is represented by the derivative of the Radon transform. This inverse problem is tightly connected with an emerging X-ray tube- and synchrotron-based imaging technique: differential phase contrast based on a grating interferometer. This study shows, that the proposed projectors, compared to space-based implementations of the same operators, yield high quality analytical and iterative reconstructions, while improving the computational efficiency by few orders of magnitude. PMID:27410628

  1. Concomitant use of polarization and positive phase contrast microscopy for the study of microbial cells.

    PubMed

    Žižka, Zdeněk; Gabriel, Jiří

    2015-11-01

    Polarization and positive phase contrast microscope were concomitantly used in the study of the internal structure of microbial cells. Positive phase contrast allowed us to view even the fine cell structure with a refractive index approaching that of the surrounding environment, e.g., the cytoplasm, and transferred the invisible phase image to a visible amplitude image. With polarization microscopy, crossed polarizing filters together with compensators and a rotary stage showed the birefringence of different cell structures. Material containing algae was collected in ponds in Sýkořice and Zbečno villages (Křivoklát region). The objects were studied in laboratory microscopes LOMO MIN-8 Sankt Petersburg and Polmi A Carl Zeiss Jena fitted with special optics for positive phase contrast, polarizers, analyzers, compensators, rotary stages, and digital SLR camera Nikon D 70 for image capture. Anisotropic granules were found in the cells of flagellates of the order Euglenales, in green algae of the orders Chlorococcales and Chlorellales, and in desmid algae of the order Desmidiales. The cell walls of filamentous algae of the orders Zygnematales and Ulotrichales were found to exhibit significant birefringence; in addition, relatively small amounts of small granules were found in the cytoplasm. A typical shape-related birefringence of the cylindrical walls and the septa between the cells differed in intensity, which was especially apparent when using a Zeiss compensator RI-c during its successive double setting. In conclusion, the anisotropic granules found in the investigated algae mostly showed strong birefringence and varied in number, size, and location of the cells. Representatives of the order Chlorococcales contained the highest number of granules per cell, and the size of these granules was almost double than that of the other monitored microorganisms. Very strong birefringence was exhibited by cell walls of filamentous algae; it differed in the intensity

  2. Characterization of a high-energy in-line phase contrast tomosynthesis prototype

    PubMed Central

    Wu, Di; Yan, Aimin; Li, Yuhua; Wong, Molly D.; Zheng, Bin; Wu, Xizeng; Liu, Hong

    2015-01-01

    Purpose: In this research, a high-energy in-line phase contrast tomosynthesis prototype was developed and characterized through quantitative investigations and phantom studies. Methods: The prototype system consists of an x-ray source, a motorized rotation stage, and a CMOS detector with a pixel pitch of 0.05 mm. The x-ray source was operated at 120 kVp for this study, and the objects were mounted on the rotation stage 76.2 cm (R1) from the source and 114.3 cm (R2) from the detector. The large air gap between the object and detector guarantees sufficient phase-shift effects. The quantitative evaluation of this prototype included modulation transfer function and noise power spectrum measurements conducted under both projection mode and tomosynthesis mode. Phantom studies were performed including three custom designed phantoms with complex structures: a five-layer bubble wrap phantom, a fishbone phantom, and a chicken breast phantom with embedded fibrils and mass structures extracted from an ACR phantom. In-plane images of the phantoms were acquired to investigate their image qualities through observation, intensity profile plots, edge enhancement evaluations, and/or contrast-to-noise ratio calculations. In addition, the robust phase-attenuation duality (PAD)-based phase retrieval method was applied to tomosynthesis for the first time in this research. It was utilized as a preprocessing method to fully exhibit phase contrast on the angular projection before reconstruction. Results: The resolution and noise characteristics of this high-energy in-line phase contrast tomosynthesis prototype were successfully investigated and demonstrated. The phantom studies demonstrated that this imaging prototype can successfully remove the structure overlapping in phantom projections, obtain delineate interfaces, and achieve better contrast-to-noise ratio after applying phase retrieval to the angular projections. Conclusions: This research successfully demonstrated a high-energy in

  3. Interlaced phase stepping in phase-contrast x-ray tomography

    NASA Astrophysics Data System (ADS)

    Zanette, I.; Bech, M.; Pfeiffer, F.; Weitkamp, T.

    2011-02-01

    We report on an interlaced acquisition scheme in grating-based x-ray phase-contrast tomography in which different viewing angles are used to retrieve a single differential phase projection. This interlaced acquisition scheme is particularly beneficial for region-of-interest tomography since it substantially reduces the artifacts caused by the external region and can eliminate the need for stop-and-go motion of the tomography rotation axis. In this letter, the higher accuracy of the region-of-interest phase reconstructions obtained with the interlaced approach is demonstrated by numerical simulation and experimental results.

  4. Phase contrast tomography of the mouse cochlea at microfocus x-ray sources

    SciTech Connect

    Bartels, Matthias; Krenkel, Martin; Hernandez, Victor H.; Moser, Tobias; Salditt, Tim

    2013-08-19

    We present phase contrast x-ray tomography of functional soft tissue within the bony cochlear capsule of mice, carried out at laboratory microfocus sources with well-matched source, detector, geometry, and reconstruction algorithms at spatial resolutions down to 2 μm. Contrast, data quality and resolution enable the visualization of thin membranes and nerve fibers as well as automated segmentation of surrounding bone. By complementing synchrotron radiation imaging techniques, a broad range of biomedical applications becomes possible as demonstrated for optogenetic cochlear implant research.

  5. Phase contrast tomography of the mouse cochlea at microfocus x-ray sources

    NASA Astrophysics Data System (ADS)

    Bartels, Matthias; Hernandez, Victor H.; Krenkel, Martin; Moser, Tobias; Salditt, Tim

    2013-08-01

    We present phase contrast x-ray tomography of functional soft tissue within the bony cochlear capsule of mice, carried out at laboratory microfocus sources with well-matched source, detector, geometry, and reconstruction algorithms at spatial resolutions down to 2 μm. Contrast, data quality and resolution enable the visualization of thin membranes and nerve fibers as well as automated segmentation of surrounding bone. By complementing synchrotron radiation imaging techniques, a broad range of biomedical applications becomes possible as demonstrated for optogenetic cochlear implant research.

  6. Projection phase contrast microscopy with a hard x-ray nanofocused beam: Defocus and contrast transfer

    SciTech Connect

    Salditt, T.; Giewekemeyer, K.; Fuhse, C.; Krueger, S. P.; Tucoulou, R.; Cloetens, P.

    2009-05-01

    We report a projection phase contrast microscopy experiment using hard x-ray pink beam undulator radiation focused by an adaptive mirror system to 100-200 nm spot size. This source is used to illuminate a lithographic test pattern with a well-controlled range of spatial frequencies. The oscillatory nature of the contrast transfer function with source-to-sample distance in this holographic imaging scheme is quantified and the validity of the weak phase object approximation is confirmed for the experimental conditions.

  7. Source effects in analyzer-based X-ray phase contrast imaging with conventional sources

    SciTech Connect

    Hoennicke, M. G.; Manica, J.; Mazzaro, I.; Cusatis, C.; Huang, X.-R.

    2012-11-15

    Several recent papers have shown the implementation of analyzer based X-ray phase contrast imaging (ABI) with conventional X-ray sources. The high flux is always a requirement to make the technique useful for bio-medical applications. Here, we present and discuss three important parameters, which need to be taken into account, when searching for the high flux ABI: anisotropic magnification, double image, and source size spread due to intrinsic dispersive diffraction by asymmetrically cut crystals. These parameters, if not well optimized, may cause important features in the acquired images which can mislead the interpretation. A few ways to minimize these effects are implemented and discussed, including some experimental results.

  8. Hard x-ray phase contrast imaging of black lipid membranes

    SciTech Connect

    Beerlink, A.; Mell, M.; Tolkiehn, M.; Salditt, T.

    2009-11-16

    We report hard x-ray phase contrast imaging of black lipid membranes, freely suspended over a micromachined aperture in an aqueous solution. Biomolecular and organic substances can thus be probed in hydrated environments by parallel beam propagation imaging, using coherent multi-kilo-electronvolt x-ray radiation. The width of the thinning film can be resolved from analysis of the intensity fringes in the Fresnel diffraction regime down to about 200 nm. The thinning process, in which solvent is expelled from the space in between two opposing monolayers, is monitored, and the domain walls between coexisting domains of swollen and thinned membrane patches are characterized.

  9. Object localization with 10 nm accuracy by x-ray phase contrast projection imaging

    SciTech Connect

    Ollinger, C.; Fuhse, C.; Kalbfleisch, S.; Tucoulou, R.; Salditt, T.

    2007-07-30

    The present work focuses on the question of localizing single object by hard x-ray phase contrast projection imaging. The authors present a setup where an x-ray channel waveguide defines a 'quasi-point source' used to illuminate and image an object in a highly coherent cone beam. Knife edge fluorescence scans revealed a beam diameter of 75 nm at a distance of 30 {mu}m behind the guide. The recorded image corresponds to an in-line hologram of the object which can be reconstructed numerically. Object translations and associated shifts in the hologram allow for the 10 nm localization accuracy.

  10. Dynamic imaging of the lungs using x-ray phase contrast

    NASA Astrophysics Data System (ADS)

    Lewis, R. A.; Yagi, N.; Kitchen, M. J.; Morgan, M. J.; Paganin, D.; Siu, K. K. W.; Pavlov, K.; Williams, I.; Uesugi, K.; Wallace, M. J.; Hall, C. J.; Whitley, J.; Hooper, S. B.

    2005-11-01

    High quality real-time imaging of lungs in vivo presents considerable challenges. We demonstrate here that phase contrast x-ray imaging is capable of dynamically imaging the lungs. It retains many of the advantages of simple x-ray imaging, whilst also being able to map weakly absorbing soft tissues based on refractive index differences. Preliminary results reported herein show that this novel imaging technique can identify and locate airway liquid and allows lung aeration in newborn rabbit pups to be dynamically visualized.

  11. Quantitative In-Line Phase-Contrast Imaging with Multienergy X Rays

    NASA Astrophysics Data System (ADS)

    Gureyev, T. E.; Mayo, S.; Wilkins, S. W.; Paganin, D.; Stevenson, A. W.

    2001-06-01

    We present a new method for quantitative nondestructive characterization of objects by x-ray phase-contrast imaging. Spatial distributions of the projected values of the complex refractive index in the sample are reconstructed by processing near-field images collected at a fixed sample-to-detector distance using a polychromatic incident beam and an energy-sensitive area detector, such as a CCD used in the photon-counting spectroscopy mode. The method has the potential advantages of decreased radiation dose and increased accuracy compared to conventional techniques of x-ray imaging.

  12. Quantitative in-line phase-contrast imaging with multienergy X rays.

    PubMed

    Gureyev, T E; Mayo, S; Wilkins, S W; Paganin, D; Stevenson, A W

    2001-06-18

    We present a new method for quantitative nondestructive characterization of objects by x-ray phase-contrast imaging. Spatial distributions of the projected values of the complex refractive index in the sample are reconstructed by processing near-field images collected at a fixed sample-to-detector distance using a polychromatic incident beam and an energy-sensitive area detector, such as a CCD used in the photon-counting spectroscopy mode. The method has the potential advantages of decreased radiation dose and increased accuracy compared to conventional techniques of x-ray imaging. PMID:11415368

  13. Ethanol fixed brain imaging by phase-contrast X-ray technique

    NASA Astrophysics Data System (ADS)

    Takeda, Tohoru; Thet-Thet-Lwin; Kunii, Takuya; Sirai, Ryota; Ohizumi, Takahito; Maruyama, Hiroko; Hyodo, Kazuyuki; Yoneyama, Akio; Ueda, Kazuhiro

    2013-03-01

    The two-crystal phase-contrast X-ray imaging technique using an X-ray crystal interferometer can depict the fine structures of rat's brain such as cerebral cortex, white matter, and basal ganglia. Image quality and contrast by ethanol fixed brain showed significantly better than those by usually used formalin fixation at 35 keV X-ray energy. Image contrast of cortex by ethanol fixation was more than 3-times higher than that by formalin fixation. Thus, the technique of ethanol fixation might be better suited to image cerebral structural detail at 35 keV X-ray energy.

  14. Halo suppression in full-field x-ray Zernike phase contrast microscopy.

    PubMed

    Vartiainen, Ismo; Mokso, Rajmund; Stampanoni, Marco; David, Christian

    2014-03-15

    Visible light Zernike phase contrast (ZPC) microscopy is a well established method for imaging weakly absorbing samples. The method is also used with hard x-ray photon energies for structural evaluation of material science and biological applications. However, the method suffers from artifacts that are inherent for the Zernike image formation. In this Letter, we investigate their origin and experimentally show how to suppress them in x-ray full-field ZPC microscopy based on diffractive x-ray optics. PMID:24690848

  15. Diffraction enhance x-ray imaging for quantitative phase contrast studies

    NASA Astrophysics Data System (ADS)

    Agrawal, A. K.; Singh, B.; Kashyap, Y. S.; Shukla, Mayank; Sarkar, P. S.; Sinha, Amar

    2016-05-01

    Conventional X-ray imaging based on absorption contrast permits limited visibility of feature having small density and thickness variations. For imaging of weakly absorbing material or materials possessing similar densities, a novel phase contrast imaging techniques called diffraction enhanced imaging has been designed and developed at imaging beamline Indus-2 RRCAT Indore. The technique provides improved visibility of the interfaces and show high contrast in the image forsmall density or thickness gradients in the bulk. This paper presents basic principle, instrumentation and analysis methods for this technique. Initial results of quantitative phase retrieval carried out on various samples have also been presented.

  16. Small animal lung imaging with an in-line X-ray phase contrast benchtop system

    NASA Astrophysics Data System (ADS)

    Garson, A. B.; Gunsten, S.; Guan, H.; Vasireddi, S.; Brody, S.; Anastasio, M. A.

    2015-03-01

    We present the results from a benchtop X-ray phase-contrast (XPC) method for lung imaging that represents a paradigm shift in the way small animal lung imaging is performed. In our method, information regarding airway microstructure that is encoded within speckle texture of a single XPC radiograph is decoded to spatially resolve changes in lung properties such as microstructure sizes, air volumes, and compliance, to name a few. Such functional information cannot be derived from conventional lung radiography or any other 2D imaging modality. By computing these images at different time points within a breathing cycle, dynamic functional imaging can be potentially achieved without the need for tomography.

  17. High sensitivity phase retrieval method in grating-based x-ray phase contrast imaging

    SciTech Connect

    Wu, Zhao; Gao, Kun; Chen, Jian; Wang, Dajiang; Wang, Shenghao; Chen, Heng; Bao, Yuan; Shao, Qigang; Wang, Zhili; Zhang, Kai; Zhu, Peiping; Wu, Ziyu

    2015-02-15

    Purpose: Grating-based x-ray phase contrast imaging is considered as one of the most promising techniques for future medical imaging. Many different methods have been developed to retrieve phase signal, among which the phase stepping (PS) method is widely used. However, further practical implementations are hindered, due to its complex scanning mode and high radiation dose. In contrast, the reverse projection (RP) method is a novel fast and low dose extraction approach. In this contribution, the authors present a quantitative analysis of the noise properties of the refraction signals retrieved by the two methods and compare their sensitivities. Methods: Using the error propagation formula, the authors analyze theoretically the signal-to-noise ratios (SNRs) of the refraction images retrieved by the two methods. Then, the sensitivities of the two extraction methods are compared under an identical exposure dose. Numerical experiments are performed to validate the theoretical results and provide some quantitative insight. Results: The SNRs of the two methods are both dependent on the system parameters, but in different ways. Comparison between their sensitivities reveals that for the refraction signal, the RP method possesses a higher sensitivity, especially in the case of high visibility and/or at the edge of the object. Conclusions: Compared with the PS method, the RP method has a superior sensitivity and provides refraction images with a higher SNR. Therefore, one can obtain highly sensitive refraction images in grating-based phase contrast imaging. This is very important for future preclinical and clinical implementations.

  18. Cryo X-ray microscopy with high spatial resolution in amplitude and phase contrast.

    PubMed

    Schneider, G

    1998-11-01

    The resolution of transmission X-ray microscopes (TXMs) using zone plate optics is presently about 30 nm. Theory and experiments presented here show that this resolution can be obtained in radiation sensitive hydrated biological material by using shock frozen samples. For this purpose the interaction of X-rays with matter and the image formation with zone plates is described. For the first time the influence of the limited apertures of the condenser and the zone plate objective are in included in calculations of the image contrast, the photon density and radiation dose required for the object illumination. Model considerations show that lowest radiation dose and high image contrast are obtained in optimized phase contrast which exploits absorption as well as phase shift. The damaging effect of the absorbed X-rays is quantitatively evaluated by radiation-induced kinetics showing that cryogenic samples are structurally stable. To verify these theoretical models the TXM was modified to allow imaging of frozen-hydrated samples at atmospheric pressure. Details inside cells and algae as small as 35 nm are visible at 2.4 nm wavelength in amplitude contrast mode. At this resolution the cryogenic samples show no structural changes. As predicted, optimized phase contrast shows structures inside the frozen-hydrated objects with high contrast. Stereo-pair images of algae reveal the 3D organization of the organelles. Element analysis and micro-tomography of whole cryogenic cells are possible. PMID:9836467

  19. Noise in x-ray grating-based phase-contrast imaging

    SciTech Connect

    Weber, Thomas; Bartl, Peter; Bayer, Florian; Durst, Juergen; Haas, Wilhelm; Michel, Thilo; Ritter, Andre; Anton, Gisela

    2011-07-15

    Purpose: Grating-based x-ray phase-contrast imaging is a fast developing new modality not only for medical imaging, but as well for other fields such as material sciences. While these many possible applications arise, the knowledge of the noise behavior is essential. Methods: In this work, the authors used a least squares fitting algorithm to calculate the noise behavior of the three quantities absorption, differential phase, and dark-field image. Further, the calculated error formula of the differential phase image was verified by measurements. Therefore, a Talbot interferometer was setup, using a microfocus x-ray tube as source and a Timepix detector for photon counting. Additionally, simulations regarding this topic were performed. Results: It turned out that the variance of the reconstructed phase is only dependent of the total number of photons used to generate the phase image and the visibility of the experimental setup. These results could be evaluated in measurements as well as in simulations. Furthermore, the correlation between absorption and dark-field image was calculated. Conclusions: These results provide the understanding of the noise characteristics of grating-based phase-contrast imaging and will help to improve image quality.

  20. Phase-contrast imaging using ultrafast x-rays in laser-shocked materials

    SciTech Connect

    Workman, Jonathan B; Cobble, James A; Flippo, Kirk; Gautier, Donald C; Montgomery, David S; Offermann, Dustin T

    2010-01-01

    High-energy x-rays, > 10-keV, can be efficiently produced from ultrafast laser target interactions with many applications to dense target materials in Inertial Confinement Fusion (ICF) and High-Energy Density Physics (HEDP). These same x-rays can also be applied to measurements of low-density materials inside high-density hohlraum environments. In the experiments presented, high-energy x-ray images of laser-shocked polystyrene are produced through phase contrast imaging. The plastic targets are nominally transparent to traditional x-ray absorption but show detailed features in regions of high density gradients due to refractive effects often called phase contrast imaging. The 200-TW Trident laser is used both to produce the x-ray source and to shock the polystyrene target. X-rays at 17-keV produced from 2-ps, 100-J laser interactions with a 12-micron molybdenum wire are used to produce a small source size, required for optimizing refractive effects. Shocks are driven in the 1-mm thick polystyrene target using 2-ns, 250-J, 532-nm laser drive with phase plates. X-ray images of shocks compare well to 1-D hydro calculations, HELIOS-CR.

  1. Processing of projections containing phase contrast in laboratory micro-computerized tomography imaging

    PubMed Central

    Zápražný, Zdenko; Korytár, Dušan; Mikulík, Petr; Áč, Vladimír

    2013-01-01

    Free-space-propagation-based imaging belongs to several techniques for achieving phase contrast in the hard X-ray range. The basic precondition is to use an X-ray beam with a high degree of coherence. Although the best sources of coherent X-rays are synchrotrons, spatially coherent X-rays emitted from a sufficiently small spot of laboratory microfocus or sub-microfocus sources allow the transfer of some of the modern imaging techniques from synchrotrons to laboratories. Spatially coherent X-rays traverse a sample leading to a phase shift. Beam deflection induced by the local change of refractive index may be expressed as a dark–bright contrast on the edges of the object in an X-ray projection. This phenomenon of edge enhancement leads to an increase in spatial resolution of X-ray projections but may also lead to unpleasant artefacts in computerized tomography unless phase and absorption contributions are separated. The possibilities of processing X-ray images of lightweight objects containing phase contrast using phase-retrieval methods in laboratory conditions are tested and the results obtained are presented. For this purpose, simulated and recorded X-ray projections taken from a laboratory imaging system with a microfocus X-ray source and a high-resolution CCD camera were processed and a qualitative comparison of results was made. PMID:24046501

  2. Absorption and Phase Contrast X-Ray Imaging in Paleontology Using Laboratory and Synchrotron Sources.

    PubMed

    Bidola, Pidassa; Stockmar, Marco; Achterhold, Klaus; Pfeiffer, Franz; Pacheco, Mírian L A F; Soriano, Carmen; Beckmann, Felix; Herzen, Julia

    2015-10-01

    X-ray micro-computed tomography (μCT) is commonly used for imaging of samples in biomedical or materials science research. Owing to the ability to visualize a sample in a nondestructive way, X-ray μCT is perfectly suited to inspect fossilized specimens, which are mostly unique or rare. In certain regions of the world where important sedimentation events occurred in the Precambrian geological time, several fossilized animals are studied to understand questions related to their origin, environment, and life evolution. This article demonstrates the advantages of applying absorption and phase-contrast CT on the enigmatic fossil Corumbella werneri, one of the oldest known animals capable of building hard parts, originally discovered in Corumbá (Brazil). Different tomographic setups were tested to visualize the fossilized inner structures: a commercial laboratory-based μCT device, two synchrotron-based imaging setups using conventional absorption and propagation-based phase contrast, and a commercial X-ray microscope with a lens-coupled detector system, dedicated for radiography and tomography. Based on our results we discuss the strengths and weaknesses of the different imaging setups for paleontological studies. PMID:26306692

  3. Statistical iterative reconstruction algorithm for X-ray phase-contrast CT

    PubMed Central

    Hahn, Dieter; Thibault, Pierre; Fehringer, Andreas; Bech, Martin; Koehler, Thomas; Pfeiffer, Franz; Noël, Peter B.

    2015-01-01

    Grating-based phase-contrast computed tomography (PCCT) is a promising imaging tool on the horizon for pre-clinical and clinical applications. Until now PCCT has been plagued by strong artifacts when dense materials like bones are present. In this paper, we present a new statistical iterative reconstruction algorithm which overcomes this limitation. It makes use of the fact that an X-ray interferometer provides a conventional absorption as well as a dark-field signal in addition to the phase-contrast signal. The method is based on a statistical iterative reconstruction algorithm utilizing maximum-a-posteriori principles and integrating the statistical properties of the raw data as well as information of dense objects gained from the absorption signal. Reconstruction of a pre-clinical mouse scan illustrates that artifacts caused by bones are significantly reduced and image quality is improved when employing our approach. Especially small structures, which are usually lost because of streaks, are recovered in our results. In comparison with the current state-of-the-art algorithms our approach provides significantly improved image quality with respect to quantitative and qualitative results. In summary, we expect that our new statistical iterative reconstruction method to increase the general usability of PCCT imaging for medical diagnosis apart from applications focused solely on soft tissue visualization. PMID:26067714

  4. High-Resolution Phase-Contrast Imaging of Submicron Particles in Unstained Lung Tissue

    NASA Astrophysics Data System (ADS)

    Schittny, J. C.; Barré, S. F.; Mokso, R.; Haberthür, D.; Semmler-Behnke, M.; Kreyling, W. G.; Tsuda, A.; Stampanoni, M.

    2011-09-01

    To access the risks and chances of deposition of submicron particles in the gas-exchange area of the lung, a precise three-dimensional (3D)-localization of the sites of deposition is essential—especially because local peaks of deposition are expected in the acinar tree and in individual alveoli. In this study we developed the workflow for such an investigation. We administered 200-nm gold particles to young adult rats by intratracheal instillation. After fixation and paraffin embedding, their lungs were imaged unstained using synchrotron radiation x-ray tomographic microscopy (SRXTM) at the beamline TOMCAT (Swiss Light Source, Villigen, Switzerland) at sample detector distances of 2.5 mm (absorption contrast) and of 52.5 mm (phase contrast). A segmentation based on a global threshold of grey levels was successfully done on absorption-contrast images for the gold and on the phase-contrast images for the tissue. The smallest spots containing gold possessed a size of 1-2 voxels of 370-nm side length. We conclude that a combination of phase and absorption contrast SRXTM imaging is necessary to obtain the correct segmentation of both tissue and gold particles. This method will be used for the 3D localization of deposited particles in the gas-exchange area of the lung.

  5. Tracking of migrating cells under phase-contrast video microscopy with combined mean-shift processes.

    PubMed

    Debeir, O; Van Ham, P; Kiss, R; Decaestecker, C

    2005-06-01

    In this paper, we propose a combination of mean-shift-based tracking processes to establish migrating cell trajectories through in vitro phase-contrast video microscopy. After a recapitulation on how the mean-shift algorithm permits efficient object tracking we describe the proposed extension and apply it to the in vitro cell tracking problem. In this application, the cells are unmarked (i.e., no fluorescent probe is used) and are observed under classical phase-contrast microscopy. By introducing an adaptive combination of several kernels, we address several problems such as variations in size and shape of the tracked objects (e.g., those occurring in the case of cell membrane extensions), the presence of incomplete (or noncontrasted) object boundaries, partially overlapping objects and object splitting (in the case of cell divisions or mitoses). Comparing the tracking results automatically obtained to those generated manually by a human expert, we tested the stability of the different algorithm parameters and their effects on the tracking results. We also show how the method is resistant to a decrease in image resolution and accidental defocusing (which may occur during long experiments, e.g., dozens of hours). Finally, we applied our methodology on cancer cell tracking and showed that cytochalasin-D significantly inhibits cell motility. PMID:15957594

  6. A novel high temporal resolution phase contrast MRI technique for measuring mitral valve flows

    NASA Astrophysics Data System (ADS)

    Voorhees, Abram; Bohmann, Katja; McGorty, Kelly Anne; Wei, Timothy; Chen, Qun

    2005-11-01

    Mitral valve flow imaging is inherently difficult due to valve plane motion and high blood flow velocities, which can range from 200 cm/s to 700 cm/s under regurgitant conditions. As such, insufficient temporal resolution has hampered imaging of mitral valve flows using magnetic resonance imaging (MRI). A novel phase contrast MRI technique, phase contrast using phase train imaging (PCPTI), has been developed to address the high temporal resolution needs for imaging mitral valve flows. The PCPTI sequence provides the highest temporal resolution to-date (6 ms) for measuring in-plane and through-plane flow patterns, with each velocity component acquired in a separate breathhold. Tested on healthy human volunteers, comparison to a conventional retrogated PC-FLASH cine sequence showed reasonable agreement. Results from a more rigorous validation using digital particle image velocimetry technique will be presented. The technique will be demonstrated in vitro using a physiological flow phantom and a St. Jude Medical Masters Series prosthetic valve.

  7. Preliminary research on dual-energy X-ray phase-contrast imaging

    NASA Astrophysics Data System (ADS)

    Han, Hua-Jie; Wang, Sheng-Hao; Gao, Kun; Wang, Zhi-Li; Zhang, Can; Yang, Meng; Zhang, Kai; Zhu, Pei-Ping

    2016-04-01

    Dual-energy X-ray absorptiometry (DEXA) has been widely applied to measure the bone mineral density (BMD) and soft-tissue composition of the human body. However, the use of DEXA is greatly limited for low-Z materials such as soft tissues due to their weak absorption, while X-ray phase-contrast imaging (XPCI) shows significantly improved contrast in comparison with the conventional standard absorption-based X-ray imaging for soft tissues. In this paper, we propose a novel X-ray phase-contrast method to measure the area density of low-Z materials, including a single-energy method and a dual-energy method. The single-energy method is for the area density calculation of one low-Z material, while the dual-energy method aims to calculate the area densities of two low-Z materials simultaneously. Comparing the experimental and simulation results with the theoretical ones, the new method proves to have the potential to replace DEXA in area density measurement. The new method sets the prerequisites for a future precise and low-dose area density calculation method for low-Z materials. Supported by Major State Basic Research Development Program (2012CB825800), Science Fund for Creative Research Groups (11321503) and National Natural Science Foundation of China (11179004, 10979055, 11205189, 11205157)

  8. X-ray phase contrast tomography by tracking near field speckle

    NASA Astrophysics Data System (ADS)

    Wang, Hongchang; Berujon, Sebastien; Herzen, Julia; Atwood, Robert; Laundy, David; Hipp, Alexander; Sawhney, Kawal

    2015-03-01

    X-ray imaging techniques that capture variations in the x-ray phase can yield higher contrast images with lower x-ray dose than is possible with conventional absorption radiography. However, the extraction of phase information is often more difficult than the extraction of absorption information and requires a more sophisticated experimental arrangement. We here report a method for three-dimensional (3D) X-ray phase contrast computed tomography (CT) which gives quantitative volumetric information on the real part of the refractive index. The method is based on the recently developed X-ray speckle tracking technique in which the displacement of near field speckle is tracked using a digital image correlation algorithm. In addition to differential phase contrast projection images, the method allows the dark-field images to be simultaneously extracted. After reconstruction, compared to conventional absorption CT images, the 3D phase CT images show greatly enhanced contrast. This new imaging method has advantages compared to other X-ray imaging methods in simplicity of experimental arrangement, speed of measurement and relative insensitivity to beam movements. These features make the technique an attractive candidate for material imaging such as in-vivo imaging of biological systems containing soft tissue.

  9. Quantitative hard x-ray phase contrast imaging of micropipes in SiC

    NASA Astrophysics Data System (ADS)

    Kohn, V. G.; Argunova, T. S.; Je, J. H.

    2013-12-01

    Peculiarities of quantitative hard x-ray phase contrast imaging of micropipes in SiC are discussed. The micropipe is assumed as a hollow cylinder with an elliptical cross section. The major and minor diameters can be restored using the least square fitting procedure by comparing the experimental data, i.e. the profile across the micropipe axis, with those calculated based on phase contrast theory. It is shown that one projection image gives an information which does not allow a complete determination of the elliptical cross section, if an orientation of micropipe is not known. Another problem is a weak accuracy in estimating the diameters, partly because of using pink synchrotron radiation, which is necessary because a monochromatic beam intensity is not sufficient to reveal the weak contrast from a very small object. The general problems of accuracy in estimating the two diameters using the least square procedure are discussed. Two experimental examples are considered to demonstrate small as well as modest accuracies in estimating the diameters.

  10. Quantitative hard x-ray phase contrast imaging of micropipes in SiC

    SciTech Connect

    Kohn, V. G.; Argunova, T. S.; Je, J. H.

    2013-12-15

    Peculiarities of quantitative hard x-ray phase contrast imaging of micropipes in SiC are discussed. The micropipe is assumed as a hollow cylinder with an elliptical cross section. The major and minor diameters can be restored using the least square fitting procedure by comparing the experimental data, i.e. the profile across the micropipe axis, with those calculated based on phase contrast theory. It is shown that one projection image gives an information which does not allow a complete determination of the elliptical cross section, if an orientation of micropipe is not known. Another problem is a weak accuracy in estimating the diameters, partly because of using pink synchrotron radiation, which is necessary because a monochromatic beam intensity is not sufficient to reveal the weak contrast from a very small object. The general problems of accuracy in estimating the two diameters using the least square procedure are discussed. Two experimental examples are considered to demonstrate small as well as modest accuracies in estimating the diameters.

  11. Cell morphology classification in phase contrast microscopy image reducing halo artifact

    NASA Astrophysics Data System (ADS)

    Kang, Mi-Sun; Song, Soo-Min; Lee, Hana; Kim, Myoung-Hee

    2012-03-01

    Since the morphology of tumor cells is a good indicator of their invasiveness, we used time-lapse phase-contrast microscopy to examine the morphology of tumor cells. This technique enables long-term observation of the activity of live cells without photobleaching and phototoxicity which is common in other fluorescence-labeled microscopy. However, it does have certain drawbacks in terms of imaging. Therefore, we first corrected for non-uniform illumination artifacts and then we use intensity distribution information to detect cell boundary. In phase contrast microscopy image, cell is normally appeared as dark region surrounded by bright halo ring. Due to halo artifact is minimal around the cell body and has non-symmetric diffusion pattern, we calculate cross sectional plane which intersects center of each cell and orthogonal to first principal axis. Then, we extract dark cell region by analyzing intensity profile curve considering local bright peak as halo area. Finally, we examined cell morphology to classify tumor cells as malignant and benign.

  12. Quantitative X-ray phase-contrast microtomography from a compact laser-driven betatron source.

    PubMed

    Wenz, J; Schleede, S; Khrennikov, K; Bech, M; Thibault, P; Heigoldt, M; Pfeiffer, F; Karsch, S

    2015-01-01

    X-ray phase-contrast imaging has recently led to a revolution in resolving power and tissue contrast in biomedical imaging, microscopy and materials science. The necessary high spatial coherence is currently provided by either large-scale synchrotron facilities with limited beamtime access or by microfocus X-ray tubes with rather limited flux. X-rays radiated by relativistic electrons driven by well-controlled high-power lasers offer a promising route to a proliferation of this powerful imaging technology. A laser-driven plasma wave accelerates and wiggles electrons, giving rise to a brilliant keV X-ray emission. This so-called betatron radiation is emitted in a collimated beam with excellent spatial coherence and remarkable spectral stability. Here we present a phase-contrast microtomogram of a biological sample using betatron X-rays. Comprehensive source characterization enables the reconstruction of absolute electron densities. Our results suggest that laser-based X-ray technology offers the potential for filling the large performance gap between synchrotron- and current X-ray tube-based sources. PMID:26189811

  13. Observation of dendritic cell morphology under light, phase-contrast or confocal laser scanning microscopy.

    PubMed

    Tan, Yuen-Fen; Leong, Chooi-Fun; Cheong, Soon-Keng

    2010-12-01

    Dendritic cells (DCs) are professional antigen presenting cells of the immune system. They can be generated in vitro from peripheral blood monocytes supplemented with GM-CSF, IL-4 and TNF alpha. During induction, DCs will increase in size and acquire multiple cytoplasmic projections when compared to their precursor cells such as monocytes or haematopoietic stem cells which are usually round or spherical. Morphology of DCs can be visualized by conventional light microscopy after staining or phase-contrast inverted microscopy or confocal laser scanning microscopy. In this report, we described the morphological appearances of DCs captured using the above-mentioned techniques. We found that confocal laser scanning microscopy yielded DCs images with greater details but the operating cost for such a technique is high. On the other hand, the images obtained through light microscopy after appropriate staining or phase contrast microscopy were acceptable for identification purpose. Besides, these equipments are readily available in most laboratories and the cost of operation is affordable. Nevertheless, morphological identification is just one of the methods to characterise DCs. Other methods such as phenotypic expression markers and mixed leukocyte reactions are additional tools used in the characterisation of DCs. PMID:21329180

  14. Gradual edge enhancement in spiral phase contrast imaging with fractional vortex filters

    PubMed Central

    Wang, Jikang; Zhang, Wuhong; Qi, Qianqian; Zheng, Shasha; Chen, Lixiang

    2015-01-01

    In the spiral phase contrast imaging, the integer spiral phase plate (SPP) are generally employed to perform the radial Hilbert transform on the object. Here we introduce fractional SPP filters, instead of the integer ones, to investigate the gradual formation of edge enhancement for pure phase objects. Two spatial light modulators are used in our experimental configuration. One is addressed to display the pure phase object of a five-pointed star, while the other serves as a dynamic filter of fractional topological charge Q. Of interest is the observation of the complete reversal of the edge and background brightness by gradually changing the fractional vortices from Q = 0 to 1. The experimental results were well interpreted based on the OAM spectra of fractional SPP, which indicates that the filtered output image can be considered as a coherent superposition of all possible images that are individually resulted from the integer OAM filtering. Besides, we show that the spiral phase contrast effect can still be observed in real time for a rotating three-leaf clover. Our results may find potential applications in the optical microscopic imaging. PMID:26510668

  15. Deciphering complex, functional structures with synchrotron-based absorption and phase contrast tomographic microscopy

    NASA Astrophysics Data System (ADS)

    Stampanoni, M.; Reichold, J.; Weber, B.; Haberthür, D.; Schittny, J.; Eller, J.; Büchi, F. N.; Marone, F.

    2010-09-01

    Nowadays, thanks to the high brilliance available at modern, third generation synchrotron facilities and recent developments in detector technology, it is possible to record volumetric information at the micrometer scale within few minutes. High signal-to-noise ratio, quantitative information on very complex structures like the brain micro vessel architecture, lung airways or fuel cells can be obtained thanks to the combination of dedicated sample preparation protocols, in-situ acquisition schemes and cutting-edge imaging analysis instruments. In this work we report on recent experiments carried out at the TOMCAT beamline of the Swiss Light Source [1] where synchrotron-based tomographic microscopy has been successfully used to obtain fundamental information on preliminary models for cerebral fluid flow [2], to provide an accurate mesh for 3D finite-element simulation of the alveolar structure of the pulmonary acinus [3] and to investigate the complex functional mechanism of fuel cells [4]. Further, we introduce preliminary results on the combination of absorption and phase contrast microscopy for the visualization of high-Z nanoparticles in soft tissues, a fundamental information when designing modern drug delivery systems [5]. As an outlook we briefly discuss the new possibilities offered by high sensitivity, high resolution grating interferomtery as well as Zernike Phase contrast nanotomography [6].

  16. Ultrasound phase contrast thermal imaging with reflex transmission imaging methods in tissue phantoms

    PubMed Central

    Farny, Caleb H.; Clement, Gregory T.

    2009-01-01

    Thermal imaging measurements using ultrasound phase contrast have been performed in tissue phantoms heated with a focused ultrasound source. Back projection and reflex transmission imaging principles were employed to detect sound speed-induced changes in the phase caused by an increase in the temperature. The temperature was determined from an empirical relationship for the temperature dependence on sound speed. The phase contrast was determined from changes in the sound field measured with a hydrophone scan conducted before and during applied heating. The lengthy scanning routine used to mimic a large two-dimensional array required a steady-state temperature distribution within the phantom. The temperature distribution in the phantom was validated with magnetic resonance (MR) thermal imaging measurements. The peak temperature was found to agree within 1°C with MR and good agreement was found between the temperature profiles. The spatial resolution was 0.3 × 0.3 × 0.3 mm, comparing favorably with the 0.625 × 0.625 × 1.5 mm MR spatial resolution. PMID:19683380

  17. Absorption and Phase Contrast X-Ray Imaging in Paleontology Using Laboratory and Synchrotron Sources

    SciTech Connect

    Bidola, Pidassa; Stockmar, Marco; Achterhold, Klaus; Pfeiffer, Franz; Pacheco, Mirian L.A.F.; Soriano, Carmen; Beckmann, Felix; Herzen, Julia

    2015-10-01

    X-ray micro-computed tomography (CT) is commonly used for imaging of samples in biomedical or materials science research. Owing to the ability to visualize a sample in a nondestructive way, X-ray CT is perfectly suited to inspect fossilized specimens, which are mostly unique or rare. In certain regions of the world where important sedimentation events occurred in the Precambrian geological time, several fossilized animals are studied to understand questions related to their origin, environment, and life evolution. This article demonstrates the advantages of applying absorption and phase-contrast CT on the enigmatic fossil Corumbella werneri, one of the oldest known animals capable of building hard parts, originally discovered in Corumba (Brazil). Different tomographic setups were tested to visualize the fossilized inner structures: a commercial laboratory-based CT device, two synchrotron-based imaging setups using conventional absorption and propagation-based phase contrast, and a commercial X-ray microscope with a lens-coupled detector system, dedicated for radiography and tomography. Based on our results we discuss the strengths and weaknesses of the different imaging setups for paleontological studies.

  18. Complex dark-field contrast in grating-based x-ray phase contrast imaging

    NASA Astrophysics Data System (ADS)

    Yang, Yi; Tang, Xiangyang

    2015-03-01

    Without assuming that the sub-pixel microstructures of an object to be imaged distribute in space randomly, we investigate the influence of the object's microstructures on grating-based x-ray phase contrast imaging. Our theoretical analysis and 3D computer simulation study based on the paraxial Fresnel-Kirchhoff theory show that the existing dark-field contrast can be generalized into a complex dark-field contrast in a way such that its imaginary part quantifies the effect of the object's sub-pixel microstructures on the phase of intensity oscillations. A method based on the phase-attenuation duality that holds for soft tissues to be imaged at high x-ray energies is proposed to retrieve the imaginary part of the complex dark-field contrast for imaging. In comparison to the existing dark-field contrast, the imaginary part of complex dark-field contrast exhibits significantly stronger selectivity on the shape of the object's sub-pixel microstructures. Thus the x-ray imaging corresponding to the imaginary part of complex dark-field contrast can provide additional and complementary information to that corresponding to the attenuation contrast, phase contrast and the existing dark-field contrast.

  19. Contrast transfer function in grating-based x-ray phase-contrast imaging

    NASA Astrophysics Data System (ADS)

    Huang, Jianheng; Du, Yang; Lin, Danying; Liu, Xin; Niu, Hanben

    2014-05-01

    x-Ray grating interferometry is a method for x-ray wave front sensing and phase-contrast imaging that has been developed over past few years. Contrast and resolution are the criteria used to specify the quality of an image. In characterizing the performance of this interferometer, the contrast transfer function is considered in this paper. The oscillatory nature of the contrast transfer function (CTF) is derived and quantified for this interferometer. The illumination source and digital detector are both considered as significant factors controlling image quality, and it can be noted that contrast and resolution in turn depends primarily on the projected intensity profile of the array source and the pixel size of the detector. Furthermore, a test pattern phantom with a well-controlled range of spatial frequencies was designed and imaging of this phantom was simulated by a computer. Contrast transfer function behavior observed in the simulated image is consistent with our theoretical CTF. This might be beneficial for the evaluation and optimization of a grating-based x-ray phase contrast imaging system.

  20. Quantitative X-ray phase-contrast microtomography from a compact laser-driven betatron source

    PubMed Central

    Wenz, J.; Schleede, S.; Khrennikov, K.; Bech, M.; Thibault, P.; Heigoldt, M.; Pfeiffer, F.; Karsch, S.

    2015-01-01

    X-ray phase-contrast imaging has recently led to a revolution in resolving power and tissue contrast in biomedical imaging, microscopy and materials science. The necessary high spatial coherence is currently provided by either large-scale synchrotron facilities with limited beamtime access or by microfocus X-ray tubes with rather limited flux. X-rays radiated by relativistic electrons driven by well-controlled high-power lasers offer a promising route to a proliferation of this powerful imaging technology. A laser-driven plasma wave accelerates and wiggles electrons, giving rise to a brilliant keV X-ray emission. This so-called betatron radiation is emitted in a collimated beam with excellent spatial coherence and remarkable spectral stability. Here we present a phase-contrast microtomogram of a biological sample using betatron X-rays. Comprehensive source characterization enables the reconstruction of absolute electron densities. Our results suggest that laser-based X-ray technology offers the potential for filling the large performance gap between synchrotron- and current X-ray tube-based sources. PMID:26189811

  1. X-ray phase contrast tomography by tracking near field speckle

    PubMed Central

    Wang, Hongchang; Berujon, Sebastien; Herzen, Julia; Atwood, Robert; Laundy, David; Hipp, Alexander; Sawhney, Kawal

    2015-01-01

    X-ray imaging techniques that capture variations in the x-ray phase can yield higher contrast images with lower x-ray dose than is possible with conventional absorption radiography. However, the extraction of phase information is often more difficult than the extraction of absorption information and requires a more sophisticated experimental arrangement. We here report a method for three-dimensional (3D) X-ray phase contrast computed tomography (CT) which gives quantitative volumetric information on the real part of the refractive index. The method is based on the recently developed X-ray speckle tracking technique in which the displacement of near field speckle is tracked using a digital image correlation algorithm. In addition to differential phase contrast projection images, the method allows the dark-field images to be simultaneously extracted. After reconstruction, compared to conventional absorption CT images, the 3D phase CT images show greatly enhanced contrast. This new imaging method has advantages compared to other X-ray imaging methods in simplicity of experimental arrangement, speed of measurement and relative insensitivity to beam movements. These features make the technique an attractive candidate for material imaging such as in-vivo imaging of biological systems containing soft tissue. PMID:25735237

  2. X-ray phase-contrast tomography for high-spatial-resolution zebrafish muscle imaging

    PubMed Central

    Vågberg, William; Larsson, Daniel H.; Li, Mei; Arner, Anders; Hertz, Hans M.

    2015-01-01

    Imaging of muscular structure with cellular or subcellular detail in whole-body animal models is of key importance for understanding muscular disease and assessing interventions. Classical histological methods for high-resolution imaging methods require excision, fixation and staining. Here we show that the three-dimensional muscular structure of unstained whole zebrafish can be imaged with sub-5 μm detail with X-ray phase-contrast tomography. Our method relies on a laboratory propagation-based phase-contrast system tailored for detection of low-contrast 4–6 μm subcellular myofibrils. The method is demonstrated on 20 days post fertilization zebrafish larvae and comparative histology confirms that we resolve individual myofibrils in the whole-body animal. X-ray imaging of healthy zebrafish show the expected structured muscle pattern while specimen with a dystrophin deficiency (sapje) displays an unstructured pattern, typical of Duchenne muscular dystrophy. The method opens up for whole-body imaging with sub-cellular detail also of other types of soft tissue and in different animal models. PMID:26564785

  3. Quantitative X-ray phase-contrast microtomography from a compact laser-driven betatron source

    NASA Astrophysics Data System (ADS)

    Wenz, J.; Schleede, S.; Khrennikov, K.; Bech, M.; Thibault, P.; Heigoldt, M.; Pfeiffer, F.; Karsch, S.

    2015-07-01

    X-ray phase-contrast imaging has recently led to a revolution in resolving power and tissue contrast in biomedical imaging, microscopy and materials science. The necessary high spatial coherence is currently provided by either large-scale synchrotron facilities with limited beamtime access or by microfocus X-ray tubes with rather limited flux. X-rays radiated by relativistic electrons driven by well-controlled high-power lasers offer a promising route to a proliferation of this powerful imaging technology. A laser-driven plasma wave accelerates and wiggles electrons, giving rise to a brilliant keV X-ray emission. This so-called betatron radiation is emitted in a collimated beam with excellent spatial coherence and remarkable spectral stability. Here we present a phase-contrast microtomogram of a biological sample using betatron X-rays. Comprehensive source characterization enables the reconstruction of absolute electron densities. Our results suggest that laser-based X-ray technology offers the potential for filling the large performance gap between synchrotron- and current X-ray tube-based sources.

  4. X-ray phase-contrast tomography for high-spatial-resolution zebrafish muscle imaging

    NASA Astrophysics Data System (ADS)

    Vågberg, William; Larsson, Daniel H.; Li, Mei; Arner, Anders; Hertz, Hans M.

    2015-11-01

    Imaging of muscular structure with cellular or subcellular detail in whole-body animal models is of key importance for understanding muscular disease and assessing interventions. Classical histological methods for high-resolution imaging methods require excision, fixation and staining. Here we show that the three-dimensional muscular structure of unstained whole zebrafish can be imaged with sub-5 μm detail with X-ray phase-contrast tomography. Our method relies on a laboratory propagation-based phase-contrast system tailored for detection of low-contrast 4-6 μm subcellular myofibrils. The method is demonstrated on 20 days post fertilization zebrafish larvae and comparative histology confirms that we resolve individual myofibrils in the whole-body animal. X-ray imaging of healthy zebrafish show the expected structured muscle pattern while specimen with a dystrophin deficiency (sapje) displays an unstructured pattern, typical of Duchenne muscular dystrophy. The method opens up for whole-body imaging with sub-cellular detail also of other types of soft tissue and in different animal models.

  5. First evidence of phase-contrast imaging with laboratory sources and active pixel sensors

    NASA Astrophysics Data System (ADS)

    Olivo, A.; Arvanitis, C. D.; Bohndiek, S. E.; Clark, A. T.; Prydderch, M.; Turchetta, R.; Speller, R. D.

    2007-11-01

    The aim of the present work is to achieve a first step towards combining the advantages of an innovative X-ray imaging technique—phase-contrast imaging (XPCi)—with those of a new class of sensors, i.e. CMOS-based active pixel sensors (APSs). The advantages of XPCi are well known and include increased image quality and detection of details invisible to conventional techniques, with potential application fields encompassing the medical, biological, industrial and security areas. Vanilla, one of the APSs developed by the MI-3 collaboration (see http://mi3.shef.ac.uk), was thoroughly characterised and an appropriate scintillator was selected to provide X-ray sensitivity. During this process, a set of phase-contrast images of different biological samples was acquired by means of the well-established free-space propagation XPCi technique. The obtained results are very encouraging and are in optimum agreement with the predictions of a simulation recently developed by some of the authors thus further supporting its reliability. This paper presents these preliminary results in detail and discusses in brief both the background to this work and its future developments.

  6. Teachable, high-content analytics for live-cell, phase contrast movies.

    PubMed

    Alworth, Samuel V; Watanabe, Hirotada; Lee, James S J

    2010-09-01

    CL-Quant is a new solution platform for broad, high-content, live-cell image analysis. Powered by novel machine learning technologies and teach-by-example interfaces, CL-Quant provides a platform for the rapid development and application of scalable, high-performance, and fully automated analytics for a broad range of live-cell microscopy imaging applications, including label-free phase contrast imaging. The authors used CL-Quant to teach off-the-shelf universal analytics, called standard recipes, for cell proliferation, wound healing, cell counting, and cell motility assays using phase contrast movies collected on the BioStation CT and BioStation IM platforms. Similar to application modules, standard recipes are intended to work robustly across a wide range of imaging conditions without requiring customization by the end user. The authors validated the performance of the standard recipes by comparing their performance with truth created manually, or by custom analytics optimized for each individual movie (and therefore yielding the best possible result for the image), and validated by independent review. The validation data show that the standard recipes' performance is comparable with the validated truth with low variation. The data validate that the CL-Quant standard recipes can provide robust results without customization for live-cell assays in broad cell types and laboratory settings. PMID:20639505

  7. Phase-only optical encryption based on the zeroth-order phase-contrast technique

    NASA Astrophysics Data System (ADS)

    Pizolato, José Carlos; Neto, Luiz Gonçalves

    2009-09-01

    A phase-only encryption/decryption scheme with the readout based on the zeroth-order phase-contrast technique (ZOPCT), without the use of a phase-changing plate on the Fourier plane of an optical system based on the 4f optical correlator, is proposed. The encryption of a gray-level image is achieved by multiplying the phase distribution obtained directly from the gray-level image by a random phase distribution. The robustness of the encoding is assured by the nonlinearity intrinsic to the proposed phase-contrast method and the random phase distribution used in the encryption process. The experimental system has been implemented with liquid-crystal spatial modulators to generate phase-encrypted masks and a decrypting key. The advantage of this method is the easy scheme to recover the gray-level information from the decrypted phase-only mask applying the ZOPCT. An analysis of this decryption method was performed against brute force attacks.

  8. Microdissection of Human Esophagogastric Junction Wall with Phase-contrast X-ray CT Imaging

    PubMed Central

    Zhang, Jianfa; Zhou, Guangzhao; Tian, Dongping; Lin, Runhua; Peng, Guanyun; Su, Min

    2015-01-01

    Phase-contrast x-ray imaging using an x-ray interferometer has great potential to reveal the structures inside soft tissues, because the sensitivity of this method to hydrogen, carbon, nitrogen, and oxygen is about 1000 times higher than that of the absorption-contrast x-ray method. In this study, we used phase-contrast X-ray CT to investigate human resected esophagogastric junction. This technology revealed the three-layer structure of the esophagogastric junction wall—mucous, submucosa and muscular layers. The mucous and muscular layers were clearly separated by a loose submucosa layer with a honeycomb appearance. The shape of the mucous and muscular layers was intact. The boundary between the mucous and submucosa layers was distinct, as was the border of the muscular and submucosa layers. The surface of the esophagogastric junction was displayed clearly through 3D reconstruction. The technology might be helpful in the diagnosis of esophagogastric junction lesion, especially for the early adenocarcinoma. PMID:26346099

  9. Phase-contrast X-ray CT Imaging of Esophagus and Esophageal Carcinoma

    PubMed Central

    Zhang, Jianfa; Tian, Dongping; Lin, Runhua; zhou, Guangzhao; Peng, Guanyun; Su, Min

    2014-01-01

    The electron density resolution is 1000 times higher for synchrotron-radiation phase-contrast CT imaging than conventional X-ray absorption imaging in light elements, with which high-resolution X-ray imaging of biological soft tissue can be achieved. In the present study, we used phase-contrast X-ray CT to investigate human resected esophagus and esophageal carcinoma specimens. This technology revealed the three-layer structure of the esophageal wall-- mucous, submucosa and muscular layers. The mucous and muscular layers were clearly separated by a loose submucosa layer with a honeycomb appearance. The surface of the mucous layer was smooth. In esophageal carcinoma, because of tumor tissue infiltration, the submucosa layer was absent, which indicated destruction of the submucosa. The boundary between normal tissue and tumor was comparatively fuzzy, the three-layer structure of the esophageal wall was indistinct. The surface of the mucous layer was rugose. The technology might be helpful in tumor staging of esophageal carcinoma. PMID:24939041

  10. Boosting phase contrast with a grating Bonse–Hart interferometer of 200 nanometre grating period

    PubMed Central

    Wen, Han; Gomella, Andrew A.; Patel, Ajay; Wolfe, Douglas E.; Lynch, Susanna K.; Xiao, Xianghui; Morgan, Nicole

    2014-01-01

    We report on a grating Bonse–Hart interferometer for phase-contrast imaging with hard X-rays. The method overcomes limitations in the level of sensitivity that can be achieved with the well-known Talbot grating interferometer, and without the stringent spectral filtering at any given incident angle imposed by the classic Bonse–Hart interferometer. The device operates in the far-field regime, where an incident beam is split by a diffraction grating into two widely separated beams, which are redirected by a second diffraction grating to merge at a third grating, where they coherently interfere. The wide separation of the interfering beams results in large phase contrast, and in some cases absolute phase images are obtained. Imaging experiments were performed using diffraction gratings of 200 nm period, at 22.5 keV and 1.5% spectral bandwidth on a bending-magnetic beamline. Novel design and fabrication process were used to achieve the small grating period. Using a slitted incident beam, we acquired absolute and differential phase images of lightly absorbing samples. An advantage of this method is that it uses only phase modulating gratings, which are easier to fabricate than absorption gratings of the same periods. PMID:24470412

  11. Quantitative imaging of electron density and effective atomic number using phase contrast CT

    NASA Astrophysics Data System (ADS)

    Qi, Zhihua; Zambelli, Joseph; Bevins, Nicholas; Chen, Guang-Hong

    2010-05-01

    Compared to single energy CT, which only provides information for x-ray linear attenuation coefficients, dual-energy CT is able to obtain both the electron density and effective atomic number for different materials in a quantitative way. In this study, as an alternative to dual-energy CT, a novel quantitative imaging method based on phase contrast CT is presented. Rather than requiring two projection data sets with different x-ray energy spectra, diffraction-grating-based phase contrast CT is capable of reconstructing images of both linear attenuation and refractive index decrement from the same projection data using a single x-ray energy spectra. From the two images, quantitative information of both the electron density and effective atomic number can be extracted. Two physical phantoms were constructed and used to validate the presented method. Experimental results demonstrate that (1) electron density can be accurately determined from refractive index decrement through a linear relationship, and (2) the effective atomic number can be explicitly derived from the ratio of the linear attenuation to refractive index decrement using a power function plus a constant. The presented method will provide insight into the technique of material separation and find its use in medical and industrial applications.

  12. Hard x-ray phase contrast imaging using single absorption grating and hybrid semiconductor pixel detector.

    PubMed

    Krejci, Frantisek; Jakubek, Jan; Kroupa, Martin

    2010-11-01

    A method for x-ray phase contrast imaging is introduced in which only one absorption grating and a microfocus x-ray source in a tabletop setup are used. The method is based on precise subpixel position determination of the x-ray pattern projected by the grating directly from the pattern image. For retrieval of the phase gradient and absorption image (both images obtained from one exposure), it is necessary to measure only one projection of the investigated object. Thus, our method is greatly simplified compared with the phase-stepping method and our method can significantly reduce the time-consuming scanning and possibly the unnecessary dose. Furthermore, the technique works with a fully polychromatic spectrum and gives ample variability in object magnification. Consequently, the approach can open the way to further widespread application of phase contrast imaging, e.g., into clinical practice. The experimental results on a simple testing object as well as on complex biological samples are presented. PMID:21133473

  13. Orientation based segmentation for phase-contrast microscopic image of confluent cell.

    PubMed

    Sasaki, K; Yuasa, T; Sasaki, H; Kato, R

    2013-01-01

    In this research, we propose a novel segmentation method for image of cultured cell at a confluent state, obtained by phase-contrast microscope, based on the orientation. First, we assign to each pixel in the image the direction of an eigenvector corresponding to a smaller eigenvalue of the 2 by 2 Hessian matrix with respect to brightness. Next, we define the orientation at a certain pixel as the histograms of the direction at pixels in the surrounding regions. Then, we evaluate deviation of histograms in the individual regions by entropy, and regard the series of entropy as a multi-dimensional vector, the dimension of which corresponds with the number of regions. We suppose that the vector is assigned to the pixel of interest. Finally, we segment the image based on the multi-dimensional vector using K-means method. We investigate the efficacy of the proposed method using an actual human confluent fibroblast image acquired by phase-contrast microscopy. PMID:24110439

  14. Abdominal thrusts

    MedlinePlus

    ... call 911 . If the person loses consciousness, start CPR . If you are not comfortable performing abdominal thrusts, ... American Red Cross. First Aid/CPR/AED Participant's Manual. 2nd ... Red Cross; 2014. Berg RA, Hemphill R, Abella BS, et al. Part 5: ...

  15. Abdominal Adhesions

    MedlinePlus

    ... Adhesions 1 Ward BC, Panitch A. Abdominal adhesions: current and novel therapies. Journal of Surgical Research. 2011;165(1):91–111. Seek Help for ... and how to participate, visit the NIH Clinical Research Trials and You website ... Foundation for Functional Gastrointestinal Disorders 700 West Virginia ...

  16. Phase contrast: the frontier of x-ray and electron imaging

    NASA Astrophysics Data System (ADS)

    Hwu, Y.; Margaritondo, G.

    2013-12-01

    Phase contrast has been a fundamental component of microscopy since the early 1940s. In broad terms, it refers to the formation of images using not the combination of wave intensities but their amplitudes with the corresponding phase factors. The impact on visible microscopy of biological specimens has been major. This contrast mechanism is now playing an increasingly important role in other kinds of microscopy, notably those based on electrons or x-rays. It notably solves the background problem of weak absorption contrast. New breakthroughs and new techniques are continuously produced, unfortunately unknown to most of the scientists that could exploit them. The present special cluster issue of reviews was inspired by this situation. The case of x-rays is very interesting. Phase contrast requires a high degree of longitudinal and lateral coherence. But conventional x-ray sources are not coherent. The progress of synchrotron sources yielded high coherence as a key byproduct—and started a rapid expansion of phase contrast radiology. No review—or cluster of reviews—can possibly cover all the facets of the recent progress. Without trying to be absolutely comprehensive, the present special cluster issue touches a variety of issues, giving a very broad picture. Liu et al review in general terms the different phase-based hard-x-ray techniques, with an interesting variety of examples. Then, Suortti et al and Wang et al present more specialized overviews of crystal and grating based x-ray imaging techniques, very powerful in the analysis of biological specimens. Mokso et al discuss the many facets of tomography using phase effects, expanding the picture of tomographic reconstruction of the three previous reviews. Wu et al treat the rapid progress in hard-x-ray focusing and its impact on radiology and tomography for materials science and biomedical research. The next two reviews deal with special and very interesting classes of applications. Specifically, Lee et al

  17. Quantitative and dynamic measurements of biological fresh samples with X-ray phase contrast tomography

    PubMed Central

    Hoshino, Masato; Uesugi, Kentaro; Tsukube, Takuro; Yagi, Naoto

    2014-01-01

    X-ray phase contrast tomography using a Talbot grating interferometer was applied to biological fresh samples which were not fixed by any fixatives. To achieve a high-throughput measurement for the fresh samples the X-ray phase contrast tomography measurement procedure was improved. The three-dimensional structure of a fresh mouse fetus was clearly depicted as a mass density map using X-ray phase contrast tomography. The mouse fetus measured in the fresh state was then fixed by formalin and measured in the fixed state. The influence of the formalin fixation on soft tissue was quantitatively evaluated by comparing the fresh and fixed samples. X-ray phase contrast tomography was also applied to the dynamic measurement of a biological fresh sample. Morphological changes of a ring-shaped fresh pig aorta were measured tomographically under different degrees of stretching. PMID:25343804

  18. Analysis of ideal observer signal detectability in phase-contrast imaging employing linear shift-invariant optical systems

    PubMed Central

    Anastasio, Mark A.; Chou, Cheng-Ying; Zysk, Adam M.; Brankov, Jovan G.

    2010-01-01

    Phase-contrast imaging methods exploit variations in an object’s refractive index distribution to permit the visualization of subtle features that may have very similar optical absorption properties. Although phase-contrast is often viewed as being desirable in many biomedical applications, its relative influence on signal detectability when both absorption- and phase-contrast are present remains relatively unexplored. In this work, we investigate the ideal Bayesian observer signal to noise ratio (SNR) in phase-contrast imaging for a signal-known-exactly/background-known exactly detection task involving a weak signal. We demonstrate that this signal detectability measure can be decomposed into three contributions that have distinct interpretations associated with the imaging physics. PMID:21119750

  19. Speckle-based x-ray phase-contrast imaging with a laboratory source and the scanning technique.

    PubMed

    Zhou, Tunhe; Zanette, Irene; Zdora, Marie-Christine; Lundström, Ulf; Larsson, Daniel H; Hertz, Hans M; Pfeiffer, Franz; Burvall, Anna

    2015-06-15

    The speckle-based scanning method for x-ray phase-contrast imaging is implemented with a liquid-metal-jet source. Using the two-dimensional scanning technique, the phase shift introduced by the object is retrieved in both transverse orientations, and the limitations on spatial resolution inherent to the speckle-tracking technique are avoided. This method opens up possibilities of new high-resolution multimodal applications for lab-based phase-contrast x-ray imaging. PMID:26076271

  20. Combined mixed approach algorithm for in-line phase-contrast x-ray imaging

    SciTech Connect

    De Caro, Liberato; Scattarella, Francesco; Giannini, Cinzia; Tangaro, Sabina; Rigon, Luigi; Longo, Renata; Bellotti, Roberto

    2010-07-15

    Purpose: In the past decade, phase-contrast imaging (PCI) has been applied to study different kinds of tissues and human body parts, with an increased improvement of the image quality with respect to simple absorption radiography. A technique closely related to PCI is phase-retrieval imaging (PRI). Indeed, PCI is an imaging modality thought to enhance the total contrast of the images through the phase shift introduced by the object (human body part); PRI is a mathematical technique to extract the quantitative phase-shift map from PCI. A new phase-retrieval algorithm for the in-line phase-contrast x-ray imaging is here proposed. Methods: The proposed algorithm is based on a mixed transfer-function and transport-of-intensity approach (MA) and it requires, at most, an initial approximate estimate of the average phase shift introduced by the object as prior knowledge. The accuracy in the initial estimate determines the convergence speed of the algorithm. The proposed algorithm retrieves both the object phase and its complex conjugate in a combined MA (CMA). Results: Although slightly less computationally effective with respect to other mixed-approach algorithms, as two phases have to be retrieved, the results obtained by the CMA on simulated data have shown that the obtained reconstructed phase maps are characterized by particularly low normalized mean square errors. The authors have also tested the CMA on noisy experimental phase-contrast data obtained by a suitable weakly absorbing sample consisting of a grid of submillimetric nylon fibers as well as on a strongly absorbing object made of a 0.03 mm thick lead x-ray resolution star pattern. The CMA has shown a good efficiency in recovering phase information, also in presence of noisy data, characterized by peak-to-peak signal-to-noise ratios down to a few dBs, showing the possibility to enhance with phase radiography the signal-to-noise ratio for features in the submillimetric scale with respect to the attenuation

  1. Abdominal Aortic Aneurysms: Treatments

    MedlinePlus

    ... information Membership Directory (SIR login) Interventional Radiology Abdominal Aortic Aneurysms Interventional Radiologists Treat Abdominal Aneurysms Nonsurgically Interventional radiologists ...

  2. Two-dimensional phase contrast interferometer for fluctuations study on LHD

    SciTech Connect

    Sanin, A.L.; Tanaka, K.; Vyacheslavov, L.N.; Kawahata, K.; Akiyama, T.

    2004-10-01

    CO{sub 2} laser based phase contrast interferometer was used previously on LHD to study plasma density microfluctuations. New two-dimensional 6x8 elements array of CdHgTe photoconductors was employed for detection. In addition to commonly measured intensity, frequency spectrum, and two-point correlation two-dimensional detector array allows determining the direction of propagation of waves in plasma. From the angular distribution it is possible to obtain localized along the viewing line properties of fluctuations using strong magnetic shear in LHD. As a result, the radial profiles of density microfluctuations can be obtained with 1 {mu}s temporal resolution determined by detector bandwidth. The described scheme was tested using ultrasonic wave in air. New imaging diagnostics has been installed on LHD and first experimental results are reported.

  3. Detection of high k turbulence using two dimensional phase contrast imaging on LHD

    SciTech Connect

    Michael, C. A.; Tanaka, K.; Akiyama, T.; Kawahata, K.; Vyacheslavov, L. N.; Sanin, A.; Kharchev, N. K.; Okajima, S.

    2008-10-15

    High k turbulence, up to 30 cm{sup -1}, can be measured using the two dimensional CO2 laser phase contrast imaging system on LHD. Recent hardware improvements and experimental results are presented. Precise control over the lens positions in the detection system is necessary because of the short depth of focus for high k modes. Remote controllable motors to move optical elements were installed, which, combined with measurements of the response to ultrasound injection, allowed experimental verification and shot-to-shot adjustment of the object plane. Strong high k signals are observed within the first 100-200 ms after the initial electron cyclotron heating (ECH) breakdown, in agreement with gyrotron scattering. During later times in the discharge, the entire k spectrum shifts to lower values (although the total amplitude does not change significantly), and the weaker high k signals are obscured by leakage of low k components at low frequency, and detector noise, at high frequency.

  4. Phase contrast x-ray velocimetry of small animal lungs: optimising imaging rates

    PubMed Central

    Murrie, R. P.; Paganin, D. M.; Fouras, A.; Morgan, K. S.

    2015-01-01

    Chronic lung diseases affect a vast portion of the world’s population. One of the key difficulties in accurately diagnosing and treating chronic lung disease is our inability to measure dynamic motion of the lungs in vivo. Phase contrast x-ray imaging (PCXI) allows us to image the lungs in high resolution by exploiting the difference in refractive indices between tissue and air. Combining PCXI with x-ray velocimetry (XV) allows us to track the local motion of the lungs, improving our ability to locate small regions of disease under natural ventilation conditions. Via simulation, we investigate the optimal imaging speed and sequence to capture lung motion in vivo in small animals using XV on both synchrotron and laboratory x-ray sources, balancing the noise inherent in a short exposure with motion blur that results from a long exposure. PMID:26819819

  5. Programmable aperture microscopy: A computational method for multi-modal phase contrast and light field imaging

    NASA Astrophysics Data System (ADS)

    Zuo, Chao; Sun, Jiasong; Feng, Shijie; Zhang, Minliang; Chen, Qian

    2016-05-01

    We demonstrate a simple and cost-effective programmable aperture microscope to realize multi-modal computational imaging by integrating a programmable liquid crystal display (LCD) into a conventional wide-field microscope. The LCD selectively modulates the light distribution at the rear aperture of the microscope objective, allowing numerous imaging modalities, such as bright field, dark field, differential phase contrast, quantitative phase imaging, multi-perspective imaging, and full resolution light field imaging to be achieved and switched rapidly in the same setup, without requiring specialized hardwares and any moving parts. We experimentally demonstrate the success of our method by imaging unstained cheek cells, profiling microlens array, and changing perspective views of thick biological specimens. The post-exposure refocusing of a butterfly mouthpart and RFP-labeled dicot stem cross-section is also presented to demonstrate the full resolution light field imaging capability of our system for both translucent and fluorescent specimens.

  6. A fast-converging iterative method for X-ray in-line phase contrast tomography

    SciTech Connect

    Vo, Nghia T.; Breese, Mark B. H.; Atwood, Robert C.; Drakopoulos, Michael; Moser, Herbert O.; Lee, Peter D.

    2012-11-26

    X-ray in-line phase contrast tomography holds great promise for the quantitative analysis of soft materials. However, its applications have been limited, so far, by the fact that direct methods based on the transport-of-intensity equation and the contrast transfer function are sensitive to noise and applicable only to limited types of samples. Here, we propose an iterative method based on the Gerchberg-Saxton algorithm (R. W. Gerchberg and W. O. Saxton, Optik 35, 237 (1972)), but overcoming its slow convergence by an acceleration technique, named random signed feedback, which shows an excellent performance, both in numerical simulation and tomographic experiment, of discriminating various polymers even when using 53 keV synchrotron X-rays.

  7. Phase contrast enhanced high resolution X-ray imaging and tomography of soft tissue

    NASA Astrophysics Data System (ADS)

    Jakubek, Jan; Granja, Carlos; Dammer, Jiri; Hanus, Robert; Holy, Tomas; Pospisil, Stanislav; Tykva, Richard; Uher, Josef; Vykydal, Zdenek

    2007-02-01

    A tabletop system for digital high resolution and high sensitivity X-ray micro-radiography has been developed for small-animal and soft-tissue imaging. The system is based on a micro-focus X-ray tube and the semiconductor hybrid position sensitive Medipix2 pixel detector. Transmission radiography imaging, conventionally based only on absorption, is enhanced by exploiting phase-shift effects induced in the X-ray beam traversing the sample. Phase contrast imaging is realized by object edge enhancement. DAQ is done by a novel fully integrated USB-based readout with online image generation. Improved signal reconstruction techniques make use of advanced statistical data analysis, enhanced beam hardening correction and direct thickness calibration of individual pixels. 2D and 3D micro-tomography images of several biological samples demonstrate the applicability of the system for biological and medical purposes including in-vivo and time dependent physiological studies in the life sciences.

  8. A tilted grating interferometer for full vector field differential x-ray phase contrast tomography.

    PubMed

    Rutishauser, Simon; Donath, Tilman; David, Christian; Pfeiffer, Franz; Marone, Federica; Modregger, Peter; Stampanoni, Marco

    2011-12-01

    We report on a setup for differential x-ray phase-contrast imaging and tomography, that measures the full 2D phase-gradient information. The setup uses a simple one-dimensional x-ray grating interferometer, in which the grating structures of the interferometer are oriented at a tilt angle with respect to the sample rotation axis. In such a configuration, the differential phase images from opposing tomography projections can be combined to yield both components of the gradient vector. We show how the refractive index distribution as well as its x, y, and z gradient components can be reconstructed directly from the recorded projection data. The method can equally well be applied at conventional x-ray tube sources, to analyzer based x-ray imaging or neutron imaging. It is demonstrated with measurements of an x-ray phantom and a rat brain using synchrotron radiation. PMID:22273882

  9. Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry

    PubMed Central

    Ophus, Colin; Ciston, Jim; Pierce, Jordan; Harvey, Tyler R.; Chess, Jordan; McMorran, Benjamin J.; Czarnik, Cory; Rose, Harald H.; Ercius, Peter

    2016-01-01

    The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, making it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals. PMID:26923483

  10. Revealing letters in rolled Herculaneum papyri by X-ray phase-contrast imaging.

    PubMed

    Mocella, Vito; Brun, Emmanuel; Ferrero, Claudio; Delattre, Daniel

    2015-01-01

    Hundreds of papyrus rolls, buried by the eruption of Mount Vesuvius in 79 AD and belonging to the only library passed on from Antiquity, were discovered 260 years ago at Herculaneum. These carbonized papyri are extremely fragile and are inevitably damaged or destroyed in the process of trying to open them to read their contents. In recent years, new imaging techniques have been developed to read the texts without unwrapping the rolls. Until now, specialists have been unable to view the carbon-based ink of these papyri, even when they could penetrate the different layers of their spiral structure. Here for the first time, we show that X-ray phase-contrast tomography can reveal various letters hidden inside the precious papyri without unrolling them. This attempt opens up new opportunities to read many Herculaneum papyri, which are still rolled up, thus enhancing our knowledge of ancient Greek literature and philosophy. PMID:25603114

  11. Note: Gratings on low absorbing substrates for x-ray phase contrast imaging

    NASA Astrophysics Data System (ADS)

    Koch, F. J.; Schröter, T. J.; Kunka, D.; Meyer, P.; Meiser, J.; Faisal, A.; Khalil, M. I.; Birnbacher, L.; Viermetz, M.; Walter, M.; Schulz, J.; Pfeiffer, F.; Mohr, J.

    2015-12-01

    Grating based X-ray phase contrast imaging is on the verge of being applied in clinical settings. To achieve this goal, compact setups with high sensitivity and dose efficiency are necessary. Both can be increased by eliminating unwanted absorption in the beam path, which is mainly due to the grating substrates. Fabrication of gratings via deep X-ray lithography can address this issue by replacing the commonly used silicon substrate with materials with lower X-ray absorption that fulfill certain boundary conditions. Gratings were produced on both graphite and polymer substrates without compromising on structure quality. These gratings were tested in a three-grating setup with a source operated at 40 kVp and lead to an increase in the detector photon count rate of almost a factor of 4 compared to a set of gratings on silicon substrates. As the visibility was hardly affected, this corresponds to a significant increase in sensitivity and therefore dose efficiency.

  12. Revealing letters in rolled Herculaneum papyri by X-ray phase-contrast imaging

    NASA Astrophysics Data System (ADS)

    Mocella, Vito; Brun, Emmanuel; Ferrero, Claudio; Delattre, Daniel

    2015-01-01

    Hundreds of papyrus rolls, buried by the eruption of Mount Vesuvius in 79 AD and belonging to the only library passed on from Antiquity, were discovered 260 years ago at Herculaneum. These carbonized papyri are extremely fragile and are inevitably damaged or destroyed in the process of trying to open them to read their contents. In recent years, new imaging techniques have been developed to read the texts without unwrapping the rolls. Until now, specialists have been unable to view the carbon-based ink of these papyri, even when they could penetrate the different layers of their spiral structure. Here for the first time, we show that X-ray phase-contrast tomography can reveal various letters hidden inside the precious papyri without unrolling them. This attempt opens up new opportunities to read many Herculaneum papyri, which are still rolled up, thus enhancing our knowledge of ancient Greek literature and philosophy.

  13. Observation of a Soft Tissue by a Zernike Phase Contrast Hard X-ray Microscope

    SciTech Connect

    Aoki, Sadao; Namikawa, Tadahiro; Hoshino, Masato; Watanabe, Norio

    2007-01-19

    A Zernike-type phase contrast hard X-ray microscope was constructed at the Photon Factory BL3C2 (KEK). A white beam from a bending magnet was monochromatized by a silicon double crystal monochromator. Monochromatic parallel X-ray beam illuminated a sample, and transmitted and diffracted X-ray beams were imaged by a Fresnel zone plate (FZP) which had the outer zone width of 100 nm. A phase plate made of a thin aluminum foil with a pinhole was set at the back focal plane of the FZP. The phase plate modulated the diffraction beam from the FZP, whereas a direct beam passed through the pinhole. The resolution of the microscope was measured by observing a tantalum test pattern at an X-ray energy of 9 keV. A 100nm line-and-space pattern could be resolved. X-ray montage pictures of growing eggs of artemia (plankton) were obtained.

  14. Compressed X-ray phase-contrast imaging using a coded source

    NASA Astrophysics Data System (ADS)

    Sung, Yongjin; Xu, Ling; Nagarkar, Vivek; Gupta, Rajiv

    2014-12-01

    X-ray phase-contrast imaging (XPCI) holds great promise for medical X-ray imaging with high soft-tissue contrast. Obviating optical elements in the imaging chain, propagation-based XPCI (PB-XPCI) has definite advantages over other XPCI techniques in terms of cost, alignment and scalability. However, it imposes strict requirements on the spatial coherence of the source and the resolution of the detector. In this study, we demonstrate that using a coded X-ray source and sparsity-based reconstruction, we can significantly relax these requirements. Using numerical simulation, we assess the feasibility of our approach and study the effect of system parameters on the reconstructed image. The results are demonstrated with images obtained using a bench-top micro-focus XPCI system.

  15. Improved image reconstruction of low-resolution multichannel phase contrast angiography.

    PubMed

    P Krishnan, Akshara; Joy, Ajin; Paul, Joseph Suresh

    2016-01-01

    In low-resolution phase contrast magnetic resonance angiography, the maximum intensity projected channel images will be blurred with consequent loss of vascular details. The channel images are enhanced using a stabilized deblurring filter, applied to each channel prior to combining the individual channel images. The stabilized deblurring is obtained by the addition of a nonlocal regularization term to the reverse heat equation, referred to as nonlocally stabilized reverse diffusion filter. Unlike reverse diffusion filter, which is highly unstable and blows up noise, nonlocal stabilization enhances intensity projected parallel images uniformly. Application to multichannel vessel enhancement is illustrated using both volunteer data and simulated multichannel angiograms. Robustness of the filter applied to volunteer datasets is shown using statistically validated improvement in flow quantification. Improved performance in terms of preserving vascular structures and phased array reconstruction in both simulated and real data is demonstrated using structureness measure and contrast ratio. PMID:26835501

  16. Toward clinical differential phase contrast mammography: preliminary evaluations and image processing schemes

    NASA Astrophysics Data System (ADS)

    Stampanoni, M.; Wang, Z.; Thüring, T.; David, C.; Rössl, E.; van Stevendaal, U.; Köhler, T.; Trippel, M.; Singer, G.; Kubik-Huch, R. A.; Hohl, M. K.; Hauser, N.

    2013-05-01

    Phase contrast and scattering-based X-ray imaging are very promising tools for medical diagnostics because they are able to provide additional and complementary information to traditional absorption-based methods. In this work, we discuss the investigation of three native breast samples with a grating interferometer equipped with a conventional X-ray tube, the full study being published in ref. [1]. We briefly introduce a method to fuse absorption, differential phase and scattering signals into a unique image with improved diagnostic contents. Our approach yields complementary and inaccessible information on the electron density distribution and the small-angle scattering power of the sample which could potentially answer clinically relevant, yet unresolved questions such as the capability to unequivocally discern between (pre-) malignant changes and post-operative scars or to distinguish cancer-invaded regions within healthy tissue.

  17. Energy Dissipation at a Shock Front in Diamond: Simulation and Comparison with Phase Contrast Imaging Data

    NASA Astrophysics Data System (ADS)

    Beckwith, Martha; Schropp, Andreas; Ping, Yuan; Swift, Damian; Collins, Gilbert

    2015-06-01

    Understanding the behavior of carbon at high pressures and temperatures is essential for predicting the structure and evolution of giant planets, such as Uranus and Neptune. Shock compression experiments on pure carbon materials, such as diamond, can provide insight into their behavior at the extreme temperatures and pressures of the giant planets. Phase contrast imaging and hydrodynamic simulations were used to examine the propagation of a shock front in diamond. As the shock front propagates through the sample, a decrease in the shock amplitude and an increase in the shock width are observed, indicating that energy dissipative processes, such as viscosity, are apparent. In addition, fractures are observed in the diamond sample behind the shock, which could also contribute to the energy dissipation at the shock front. Work at LLNL performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  18. Asymmetric masks for laboratory-based X-ray phase-contrast imaging with edge illumination

    NASA Astrophysics Data System (ADS)

    Endrizzi, Marco; Astolfo, Alberto; Vittoria, Fabio A.; Millard, Thomas P.; Olivo, Alessandro

    2016-05-01

    We report on an asymmetric mask concept that enables X-ray phase-contrast imaging without requiring any movement in the system during data acquisition. The method is compatible with laboratory equipment, namely a commercial detector and a rotating anode tube. The only motion required is that of the object under investigation which is scanned through the imaging system. Two proof-of-principle optical elements were designed, fabricated and experimentally tested. Quantitative measurements on samples of known shape and composition were compared to theory with good agreement. The method is capable of measuring the attenuation, refraction and (ultra-small-angle) X-ray scattering, does not have coherence requirements and naturally adapts to all those situations in which the X-ray image is obtained by scanning a sample through the imaging system.

  19. Long-term quantitative phase-contrast imaging of living cells by digital holographic microscopy

    NASA Astrophysics Data System (ADS)

    Liu, S.; Pan, F.; Wang, Z.; Wang, F.; Rong, L.; Shang, P.; Xiao, W.

    2011-04-01

    The dynamic analysis of biological living samples is one of the particular interests in life sciences. An improved digital holographic microscope for long-term quantitative phase-contrast imaging of living cells is presented in this paper. The optical configuration is optimized in the form of a free-space-fiber hybrid system which promotes the flexibility of imaging in complex or semi-enclosed experimental environment. Aberrations compensation is implemented taking into account the additional phase aberration induced by liquid culture medium in long-term observation. The proposed approach is applied to investigate living samples of MC3T3-E1 and MLO-Y4 cells. The experimental results demonstrate its availability in the analysis of cellular changes.

  20. Real-time measurement of alveolar size and population using phase contrast x-ray imaging

    PubMed Central

    Leong, Andrew F.T.; Buckley, Genevieve A.; Paganin, David M.; Hooper, Stuart B.; Wallace, Megan J.; Kitchen, Marcus J.

    2014-01-01

    Herein a propagation-based phase contrast x-ray imaging technique for measuring particle size and number is presented. This is achieved with an algorithm that utilizes the Fourier space signature of the speckle pattern associated with the images of particles. We validate this algorithm using soda-lime glass particles, demonstrating its effectiveness on random and non-randomly packed particles. This technique is then applied to characterise lung alveoli, which are difficult to measure dynamically in vivo with current imaging modalities due to inadequate temporal resolution and/or depth of penetration and field-of-view. We obtain an important result in that our algorithm is able to measure changes in alveolar size on the micron scale during ventilation and shows the presence of alveolar recruitment/de-recruitment in newborn rabbit kittens. This technique will be useful for ventilation management and lung diagnostic procedures. PMID:25426328

  1. A method for automatic liver segmentation from multi-phase contrast-enhanced CT images

    NASA Astrophysics Data System (ADS)

    Yuan, Rong; Luo, Ming; Wang, Shaofa; Wang, Luyao; Xie, Qingguo

    2014-03-01

    Liver segmentation is a basic and indispensable function in systems of computer aided liver surgery for volume calculation, operation designing and risk evaluation. Traditional manual segmentation is very time consuming because of the complicated contours of liver and the big amount of images. For increasing the efficiency of the clinical work, in this paper, a fully-automatic method was proposed to segment the liver from multi-phase contrast-enhanced computed tomography (CT) images. As an advanced region growing method, we applied various pre- and post-processing to get better segmentation from the different phases. Fifteen sets of clinical abdomens CT images of five patients were segmented by our algorithm, and the results were acceptable and evaluated by an experienced surgeon. The running-time is about 30 seconds for a single-phase data which includes more than 200 slices.

  2. Microbubbles as contrast agent for in-line x-ray phase-contrast imaging

    SciTech Connect

    Xi Yan; Zhao Jun; Tang Rongbiao; Wang Yujie

    2011-07-04

    In the present study, we investigated the potential of gas-filled microbubbles as contrast agents for in-line x-ray phase-contrast imaging (PCI) in biomedical applications. When imaging parameters are optimized, the microbubbles function as microlenses that focus the incoming x-rays to form bright spots, which can significantly enhance the image contrast. Since microbubbles have been shown to be safe contrast agents in clinical ultrasonography, this contrast-enhancement procedure for PCI may have promising utility in biomedical applications, especially when the dose of radiation is a serious concern. In this study, we performed both numerical simulations and ex vivo experiments to investigate the formation of the contrast and the effectiveness of microbubbles as contrast agents in PCI.

  3. Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry

    NASA Astrophysics Data System (ADS)

    Ophus, Colin; Ciston, Jim; Pierce, Jordan; Harvey, Tyler R.; Chess, Jordan; McMorran, Benjamin J.; Czarnik, Cory; Rose, Harald H.; Ercius, Peter

    2016-02-01

    The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, making it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals.

  4. A fast-converging iterative method for X-ray in-line phase contrast tomography

    NASA Astrophysics Data System (ADS)

    Vo, Nghia T.; Atwood, Robert C.; Moser, Herbert O.; Lee, Peter D.; Breese, Mark B. H.; Drakopoulos, Michael

    2012-11-01

    X-ray in-line phase contrast tomography holds great promise for the quantitative analysis of soft materials. However, its applications have been limited, so far, by the fact that direct methods based on the transport-of-intensity equation and the contrast transfer function are sensitive to noise and applicable only to limited types of samples. Here, we propose an iterative method based on the Gerchberg-Saxton algorithm (R. W. Gerchberg and W. O. Saxton, Optik 35, 237 (1972)), but overcoming its slow convergence by an acceleration technique, named random signed feedback, which shows an excellent performance, both in numerical simulation and tomographic experiment, of discriminating various polymers even when using 53 keV synchrotron X-rays.

  5. Measurement of depth-resolved thermal deformation distribution using phase-contrast spectral optical coherence tomography.

    PubMed

    Zhang, Yun; Dong, Bo; Bai, Yulei; Ye, Shuangli; Lei, Zhenkun; Zhou, Yanzhou

    2015-10-19

    An updated B-scan method is proposed for measuring the evolution of thermal deformation fields in polymers. In order to measure the distributions of out-of-plane deformation and normal strain field, phase-contrast spectral optical coherence tomography (PC-SOCT) was performed with the depth range and resolution of 4.3 mm and 10.7 μm, respectively, as thermal loads were applied to three different multilayer samples. The relation between temperature and material refractive index was predetermined before the measurement. After accounting for the refractive index, the thermal deformation fields in the polymer were obtained. The measured thermal expansion coefficient of silicone sealant was approximately equal to its reference value. This method allows correctly assessing the mechanical properties in semitransparent polymers. PMID:26480464

  6. Design of a novel phase contrast x-ray imaging system for mammography.

    PubMed

    Munro, Peter R T; Ignatyev, Konstantin; Speller, Robert D; Olivo, Alessandro

    2010-07-21

    It is hoped that x-ray phase contrast imaging (XPCi) will provide a generational improvement in the effectiveness of mammography. XPCi is sensitive to the refraction which x-rays undergo as a result of the variation in x-ray propagation speeds within an object. XPCi is, however, seldom used in clinical applications owing mainly to a lack of suitable systems. The radiation physics group at UCL has previously designed and built an XPCi system sensitive to phase gradients in one dimension for application in security inspection. We present here the design methodology and final design of a prototype XPCi system sensitive to phase gradients in two directions for use in mammography. The technique makes efficient use of the flux available from a laboratory x-ray source, thus making it suitable for clinical use. PMID:20601778

  7. Big-data x-ray phase contrast imaging simulation challenges

    NASA Astrophysics Data System (ADS)

    Jimenez, Edward S.; Dagel, Amber L.

    2015-08-01

    This position paper describes a potential implementation of a large-scale grating-based X-ray Phase Contrast Imaging System (XPCI) simulation tool along with the associated challenges in its implementation. This work proposes an implementation based off of an implementation by Peterzol et. al. where each grating is treated as an object imaged in the field-of-view. Two main challenges exist; the first, is the required sampling and information management in object space due to the micron-scale periods of each grating propagating over significant distances. The second is maintaining algorithmic numerical stability for imaging systems relevant to industrial applications. We present preliminary results for a numerical stability study using a simplified algorithm that performs Talbot imaging in a big-data context

  8. On-sky performance of the Zernike phase contrast sensor for the phasing of segmented telescopes.

    PubMed

    Surdej, Isabelle; Yaitskova, Natalia; Gonte, Frederic

    2010-07-20

    The Zernike phase contrast method is a novel technique to phase the primary mirrors of segmented telescopes. It has been tested on-sky on a unit telescope of the Very Large Telescope with a segmented mirror conjugated to the primary mirror to emulate a segmented telescope. The theoretical background of this sensor and the algorithm used to retrieve the piston, tip, and tilt information are described. The performance of the sensor as a function of parameters such as star magnitude, seeing, and integration time is discussed. The phasing accuracy has always been below 15 nm root mean square wavefront error under normal conditions of operation and the limiting star magnitude achieved on-sky with this sensor is 15.7 in the red, which would be sufficient to phase segmented telescopes in closed-loop during observations. PMID:20648188

  9. Primary ciliary dyskinesia assessment by means of optical flow analysis of phase-contrast microscopy images.

    PubMed

    Parrilla, Eduardo; Armengot, Miguel; Mata, Manuel; Sánchez-Vílchez, José Manuel; Cortijo, Julio; Hueso, José L; Riera, Jaime; Moratal, David

    2014-04-01

    Primary ciliary dyskinesia implies cilia with defective or total absence of motility, which may result in sinusitis, chronic bronchitis, bronchiectasis and male infertility. Diagnosis can be difficult and is based on an abnormal ciliary beat frequency (CBF) and beat pattern. In this paper, we present a method to determine CBF of isolated cells through the analysis of phase-contrast microscopy images, estimating cilia motion by means of an optical flow algorithm. After having analyzed 28 image sequences (14 with a normal beat pattern and 14 with a dyskinetic pattern), the normal group presented a CBF of 5.2 ± 1.6 Hz, while the dyskinetic patients presented a 1.9 ± 0.9 Hz CBF. The cutoff value to classify a dyskinetic specimen was set to 3.45 Hz (sensitivity 0.86, specificity 0.93). The presented methodology has provided excellent results to objectively diagnose PCD. PMID:24438822

  10. Compact laser accelerators for X-ray phase-contrast imaging.

    PubMed

    Najmudin, Z; Kneip, S; Bloom, M S; Mangles, S P D; Chekhlov, O; Dangor, A E; Döpp, A; Ertel, K; Hawkes, S J; Holloway, J; Hooker, C J; Jiang, J; Lopes, N C; Nakamura, H; Norreys, P A; Rajeev, P P; Russo, C; Streeter, M J V; Symes, D R; Wing, M

    2014-03-01

    Advances in X-ray imaging techniques have been driven by advances in novel X-ray sources. The latest fourth-generation X-ray sources can boast large photon fluxes at unprecedented brightness. However, the large size of these facilities means that these sources are not available for everyday applications. With advances in laser plasma acceleration, electron beams can now be generated at energies comparable to those used in light sources, but in university-sized laboratories. By making use of the strong transverse focusing of plasma accelerators, bright sources of betatron radiation have been produced. Here, we demonstrate phase-contrast imaging of a biological sample for the first time by radiation generated by GeV electron beams produced by a laser accelerator. The work was performed using a greater than 300 TW laser, which allowed the energy of the synchrotron source to be extended to the 10-100 keV range. PMID:24470414

  11. Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry.

    PubMed

    Ophus, Colin; Ciston, Jim; Pierce, Jordan; Harvey, Tyler R; Chess, Jordan; McMorran, Benjamin J; Czarnik, Cory; Rose, Harald H; Ercius, Peter

    2016-01-01

    The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, making it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals. PMID:26923483

  12. Virtual unrolling and deciphering of Herculaneum papyri by X-ray phase-contrast tomography.

    PubMed

    Bukreeva, I; Mittone, A; Bravin, A; Festa, G; Alessandrelli, M; Coan, P; Formoso, V; Agostino, R G; Giocondo, M; Ciuchi, F; Fratini, M; Massimi, L; Lamarra, A; Andreani, C; Bartolino, R; Gigli, G; Ranocchia, G; Cedola, A

    2016-01-01

    A collection of more than 1800 carbonized papyri, discovered in the Roman 'Villa dei Papiri' at Herculaneum is the unique classical library survived from antiquity. These papyri were charred during 79 A.D. Vesuvius eruption, a circumstance which providentially preserved them until now. This magnificent collection contains an impressive amount of treatises by Greek philosophers and, especially, Philodemus of Gadara, an Epicurean thinker of 1st century BC. We read many portions of text hidden inside carbonized Herculaneum papyri using enhanced X-ray phase-contrast tomography non-destructive technique and a new set of numerical algorithms for 'virtual-unrolling'. Our success lies in revealing the largest portion of Greek text ever detected so far inside unopened scrolls, with unprecedented spatial resolution and contrast, all without damaging these precious historical manuscripts. Parts of text have been decoded and the 'voice' of the Epicurean philosopher Philodemus is brought back again after 2000 years from Herculaneum papyri. PMID:27265417

  13. Comparison of two x-ray phase-contrast imaging methods with a microfocus source.

    PubMed

    Zhou, T; Lundström, U; Thüring, T; Rutishauser, S; Larsson, D H; Stampanoni, M; David, C; Hertz, H M; Burvall, A

    2013-12-16

    We present a comparison for high-resolution imaging with a laboratory source between grating-based (GBI) and propagation-based (PBI) x-ray phase-contrast imaging. The comparison is done through simulations and experiments using a liquid-metal-jet x-ray microfocus source. Radiation doses required for detection in projection images are simulated as a function of the diameter of a cylindrical sample. Using monochromatic radiation, simulations show a lower dose requirement for PBI for small object features and a lower dose for GBI for larger object features. Using polychromatic radiation, such as that from a laboratory microfocus source, experiments and simulations show a lower dose requirement for PBI for a large range of feature sizes. Tested on a biological sample, GBI shows higher noise levels than PBI, but its advantage of quantitative refractive index reconstruction for multi-material samples becomes apparent. PMID:24514597

  14. Monte Carlo model of a polychromatic laboratory based edge illumination x-ray phase contrast system.

    PubMed

    Millard, T P; Endrizzi, M; Diemoz, P C; Hagen, C K; Olivo, A

    2014-05-01

    A Monte Carlo model of a polychromatic laboratory based (coded aperture) edge illumination x-ray phase contrast imaging system has been developed and validated against experimental data. The ability for the simulation framework to be used to model two-dimensional images is also shown. The Monte Carlo model has been developed using the McXtrace engine and is polychromatic, i.e., results are obtained through the use of the full x-ray spectrum rather than an effective energy. This type of simulation can in future be used to model imaging of objects with complex geometry, for system prototyping, as well as providing a first step towards the development of a simulation for modelling dose delivery as a part of translating the imaging technique for use in clinical environments. PMID:24880377

  15. Asymmetric masks for laboratory-based X-ray phase-contrast imaging with edge illumination

    PubMed Central

    Endrizzi, Marco; Astolfo, Alberto; Vittoria, Fabio A.; Millard, Thomas P.; Olivo, Alessandro

    2016-01-01

    We report on an asymmetric mask concept that enables X-ray phase-contrast imaging without requiring any movement in the system during data acquisition. The method is compatible with laboratory equipment, namely a commercial detector and a rotating anode tube. The only motion required is that of the object under investigation which is scanned through the imaging system. Two proof-of-principle optical elements were designed, fabricated and experimentally tested. Quantitative measurements on samples of known shape and composition were compared to theory with good agreement. The method is capable of measuring the attenuation, refraction and (ultra-small-angle) X-ray scattering, does not have coherence requirements and naturally adapts to all those situations in which the X-ray image is obtained by scanning a sample through the imaging system. PMID:27145924

  16. Note: Gratings on low absorbing substrates for x-ray phase contrast imaging

    SciTech Connect

    Koch, F. J. Schröter, T. J.; Kunka, D.; Meyer, P.; Meiser, J.; Faisal, A.; Khalil, M. I.; Mohr, J.; Birnbacher, L.; Viermetz, M.; Pfeiffer, F.; Walter, M.; Schulz, J.

    2015-12-15

    Grating based X-ray phase contrast imaging is on the verge of being applied in clinical settings. To achieve this goal, compact setups with high sensitivity and dose efficiency are necessary. Both can be increased by eliminating unwanted absorption in the beam path, which is mainly due to the grating substrates. Fabrication of gratings via deep X-ray lithography can address this issue by replacing the commonly used silicon substrate with materials with lower X-ray absorption that fulfill certain boundary conditions. Gratings were produced on both graphite and polymer substrates without compromising on structure quality. These gratings were tested in a three-grating setup with a source operated at 40 kVp and lead to an increase in the detector photon count rate of almost a factor of 4 compared to a set of gratings on silicon substrates. As the visibility was hardly affected, this corresponds to a significant increase in sensitivity and therefore dose efficiency.

  17. Image reconstruction exploiting object sparsity in boundary-enhanced X-ray phase-contrast tomography.

    PubMed

    Sidky, Emil Y; Anastasio, Mark A; Pan, Xiaochuan

    2010-05-10

    Propagation-based X-ray phase-contrast tomography (PCT) seeks to reconstruct information regarding the complex-valued refractive index distribution of an object. In many applications, a boundary-enhanced image is sought that reveals the locations of discontinuities in the real-valued component of the refractive index distribution. We investigate two iterative algorithms for few-view image reconstruction in boundary-enhanced PCT that exploit the fact that a boundary-enhanced PCT image, or its gradient, is often sparse. In order to exploit object sparseness, the reconstruction algorithms seek to minimize the l(1)-norm or TV-norm of the image, subject to data consistency constraints. We demonstrate that the algorithms can reconstruct accurate boundary-enhanced images from highly incomplete few-view projection data. PMID:20588896

  18. Real-time measurement of alveolar size and population using phase contrast x-ray imaging.

    PubMed

    Leong, Andrew F T; Buckley, Genevieve A; Paganin, David M; Hooper, Stuart B; Wallace, Megan J; Kitchen, Marcus J

    2014-11-01

    Herein a propagation-based phase contrast x-ray imaging technique for measuring particle size and number is presented. This is achieved with an algorithm that utilizes the Fourier space signature of the speckle pattern associated with the images of particles. We validate this algorithm using soda-lime glass particles, demonstrating its effectiveness on random and non-randomly packed particles. This technique is then applied to characterise lung alveoli, which are difficult to measure dynamically in vivo with current imaging modalities due to inadequate temporal resolution and/or depth of penetration and field-of-view. We obtain an important result in that our algorithm is able to measure changes in alveolar size on the micron scale during ventilation and shows the presence of alveolar recruitment/de-recruitment in newborn rabbit kittens. This technique will be useful for ventilation management and lung diagnostic procedures. PMID:25426328

  19. Asymmetric masks for laboratory-based X-ray phase-contrast imaging with edge illumination.

    PubMed

    Endrizzi, Marco; Astolfo, Alberto; Vittoria, Fabio A; Millard, Thomas P; Olivo, Alessandro

    2016-01-01

    We report on an asymmetric mask concept that enables X-ray phase-contrast imaging without requiring any movement in the system during data acquisition. The method is compatible with laboratory equipment, namely a commercial detector and a rotating anode tube. The only motion required is that of the object under investigation which is scanned through the imaging system. Two proof-of-principle optical elements were designed, fabricated and experimentally tested. Quantitative measurements on samples of known shape and composition were compared to theory with good agreement. The method is capable of measuring the attenuation, refraction and (ultra-small-angle) X-ray scattering, does not have coherence requirements and naturally adapts to all those situations in which the X-ray image is obtained by scanning a sample through the imaging system. PMID:27145924

  20. Tumors in murine brains studied by grating-based phase contrast microtomography

    NASA Astrophysics Data System (ADS)

    Schulz, Georg; Dominietto, Marco; Kovacs, Zsofia; Schmitz, Rüdiger; Hieber, Simone E.; Thalmann, Peter; Beckmann, Felix; Müller, Bert

    2014-09-01

    Angiogenesis, i.e. the formation of vessels, is one of the key processes during tumor development. The newly formed vessels transport oxygen and nutrients from the healthy tissue to the tumor and gives tumor cells the possibility to replicate. The principle of anti-angiogenic therapy is to block angiogenic process in order to stop tumor growth. The aim of the present study is the investigation of murine glioma vascular architecture at early (7 days), intermediate (10 and 15 days) and late (23 days) stage of growth by means of grating-based phase contrast microtomography. We demonstrate that this technique yields premium contrast between healthy and cancerous parts of murine brain tissues.

  1. Observation of a Soft Tissue by a Zernike Phase Contrast Hard X-ray Microscope

    NASA Astrophysics Data System (ADS)

    Aoki, Sadao; Namikawa, Tadahiro; Hoshino, Masato; Watanabe, Norio

    2007-01-01

    A Zernike-type phase contrast hard X-ray microscope was constructed at the Photon Factory BL3C2 (KEK). A white beam from a bending magnet was monochromatized by a silicon double crystal monochromator. Monochromatic parallel X-ray beam illuminated a sample, and transmitted and diffracted X-ray beams were imaged by a Fresnel zone plate (FZP) which had the outer zone width of 100 nm. A phase plate made of a thin aluminum foil with a pinhole was set at the back focal plane of the FZP. The phase plate modulated the diffraction beam from the FZP, whereas a direct beam passed through the pinhole. The resolution of the microscope was measured by observing a tantalum test pattern at an X-ray energy of 9 keV. A 100nm line-and-space pattern could be resolved. X-ray montage pictures of growing eggs of artemia (plankton) were obtained.

  2. Automatic neuron segmentation and neural network analysis method for phase contrast microscopy images

    PubMed Central

    Pang, Jincheng; Özkucur, Nurdan; Ren, Michael; Kaplan, David L.; Levin, Michael; Miller, Eric L.

    2015-01-01

    Phase Contrast Microscopy (PCM) is an important tool for the long term study of living cells. Unlike fluorescence methods which suffer from photobleaching of fluorophore or dye molecules, PCM image contrast is generated by the natural variations in optical index of refraction. Unfortunately, the same physical principles which allow for these studies give rise to complex artifacts in the raw PCM imagery. Of particular interest in this paper are neuron images where these image imperfections manifest in very different ways for the two structures of specific interest: cell bodies (somas) and dendrites. To address these challenges, we introduce a novel parametric image model using the level set framework and an associated variational approach which simultaneously restores and segments this class of images. Using this technique as the basis for an automated image analysis pipeline, results for both the synthetic and real images validate and demonstrate the advantages of our approach. PMID:26601004

  3. Phase Contrast X-Ray Synchrotron Microtomography for Virtual Dissection of the Head of Rhodnius prolixus

    NASA Astrophysics Data System (ADS)

    Sena, G.; Almeida, A. P.; Braz, D.; Nogueira, L. P.; Colaço, M. V.; Soares, J.; Cardoso, S. C.; Garcia, E. S.; Azambuja, P.; Gonzalez, M. S.; Mohammadi, S.; Tromba, G.; Barroso, R. C.

    2014-04-01

    Phase Contrast X-Ray Synchroton Microtomography is a non-destructive technique that allows the microanatomical investigations of Rhodnius prolixus, one of the most important insect vectors of Trypanosoma cruzi. In this work complete series of virtual thin sections through the heads of selected Rhodnius prolixus were obtained. The sections of the head were important to compare the difference in use the spatial resolution of 2 μm or 4.5 μm and to see anatomical details that couldn't be seen with other technique. Three different groups of Rhodnius prolixus were used. One group was fed with defibrinated rabbit blood and after 10 days was sacrificed, other group was sacrificed 4 days after feeding and the last group remained unfed. The results show some differences for each kind of groups and for the different resolutions.

  4. Phase-contrast x-ray imaging and tomography of the nematode Caenorhabditis elegans

    NASA Astrophysics Data System (ADS)

    Olendrowitz, C.; Bartels, M.; Krenkel, M.; Beerlink, A.; Mokso, R.; Sprung, M.; Salditt, T.

    2012-08-01

    We have analyzed the model organism Caenorhabditis elegans with the help of phase-contrast x-ray tomography. This work combines techniques from x-ray imaging studies of single biological cells by in-line holography with three-dimensional reconstruction and furthermore extends these studies to the multicellular level. To preserve the sub-cellular ultrastructure of the nematodes, we used the near-native sample preparation of high-pressure freezing as commonly used in the field of electron microscopy. For the presented samples, a standard, non-magnifying parallel-beam setting, as well as a magnifying, divergent-beam setting using nanofocusing optics is evaluated based on their tomographic reconstruction potential. In this paper, we address difficulties in sample preparation and issues of image processing. By experimental refinement and through optimized reconstruction procedures, we were able to perform x-ray imaging studies on a living specimen.

  5. Detection of high k turbulence using two dimensional phase contrast imaging on LHD.

    PubMed

    Michael, C A; Tanaka, K; Vyacheslavov, L N; Sanin, A; Kharchev, N K; Akiyama, T; Kawahata, K; Okajima, S

    2008-10-01

    High k turbulence, up to 30 cm(-1), can be measured using the two dimensional CO2 laser phase contrast imaging system on LHD. Recent hardware improvements and experimental results are presented. Precise control over the lens positions in the detection system is necessary because of the short depth of focus for high k modes. Remote controllable motors to move optical elements were installed, which, combined with measurements of the response to ultrasound injection, allowed experimental verification and shot-to-shot adjustment of the object plane. Strong high k signals are observed within the first 100-200 ms after the initial electron cyclotron heating (ECH) breakdown, in agreement with gyrotron scattering. During later times in the discharge, the entire k spectrum shifts to lower values (although the total amplitude does not change significantly), and the weaker high k signals are obscured by leakage of low k components at low frequency, and detector noise, at high frequency. PMID:19044541

  6. Zernike Phase Contrast Electron Cryo-Tomography Applied to Marine Cyanobacteria Infected with Cyanophages

    PubMed Central

    Dai, Wei; Fu, Caroline; Khant, Htet A.; Ludtke, Steven J.; Schmid, Michael F.; Chiu, Wah

    2015-01-01

    Advances in electron cryo-tomography have provided a new opportunity to visualize the internal 3D structures of a bacterium. An electron microscope equipped with Zernike phase contrast optics produces images with dramatically increased contrast compared to images obtained by conventional electron microscopy. Here we describe a protocol to apply Zernike phase plate technology for acquiring electron tomographic tilt series of cyanophage-infected cyanobacterial cells embedded in ice, without staining or chemical fixation. We detail the procedures for aligning and assessing phase plates for data collection, and methods to obtain 3D structures of cyanophage assembly intermediates in the host, by subtomogram alignment, classification and averaging. Acquiring three to four tomographic tilt series takes approximately 12 h on a JEM2200FS electron microscope. We expect this time requirement to decrease substantially as the technique matures. Time required for annotation and subtomogram averaging varies widely depending on the project goals and data volume. PMID:25321408

  7. Compact laser accelerators for X-ray phase-contrast imaging

    PubMed Central

    Najmudin, Z.; Kneip, S.; Bloom, M. S.; Mangles, S. P. D.; Chekhlov, O.; Dangor, A. E.; Döpp, A.; Ertel, K.; Hawkes, S. J.; Holloway, J.; Hooker, C. J.; Jiang, J.; Lopes, N. C.; Nakamura, H.; Norreys, P. A.; Rajeev, P. P.; Russo, C.; Streeter, M. J. V.; Symes, D. R.; Wing, M.

    2014-01-01

    Advances in X-ray imaging techniques have been driven by advances in novel X-ray sources. The latest fourth-generation X-ray sources can boast large photon fluxes at unprecedented brightness. However, the large size of these facilities means that these sources are not available for everyday applications. With advances in laser plasma acceleration, electron beams can now be generated at energies comparable to those used in light sources, but in university-sized laboratories. By making use of the strong transverse focusing of plasma accelerators, bright sources of betatron radiation have been produced. Here, we demonstrate phase-contrast imaging of a biological sample for the first time by radiation generated by GeV electron beams produced by a laser accelerator. The work was performed using a greater than 300 TW laser, which allowed the energy of the synchrotron source to be extended to the 10–100 keV range. PMID:24470414

  8. Event detection by feature unpredictability in phase-contrast videos of cell cultures.

    PubMed

    Kandemir, Melih; Rubio, Jose C; Schmidt, Ute; Wojek, Christian; Welbl, Johannes; Ommer, Björn; Hamprecht, Fred A

    2014-01-01

    In this work we propose a novel framework for generic event monitoring in live cell culture videos, built on the assumption that unpredictable observations should correspond to biological events. We use a small set of event-free data to train a multioutput multikernel Gaussian process model that operates as an event predictor by performing autoregression on a bank of heterogeneous features extracted from consecutive frames of a video sequence. We show that the prediction error of this model can be used as a probability measure of the presence of relevant events, that can enable users to perform further analysis or monitoring of large-scale non-annotated data. We validate our approach in two phase-contrast sequence data sets containing mitosis and apoptosis events: a new private dataset of human bone cancer (osteosarcoma) cells and a benchmark dataset of stem cells. PMID:25485374

  9. Interpretation of Line-Integrated Signals from 2-D Phase Contrast Imaging on LHD

    NASA Astrophysics Data System (ADS)

    Michael, Clive; Tanaka, Kenji; Vyacheslavov, Leonid; Sanin, Andrei; Kawahata, Kazuo; Okajima, S.

    Two dimensional (2D) phase contrast imaging (PCI) is an excellent method to measure core and edge turbulence with good spatial resolution (Δρ ˜ 0.1). General analytical consideration is given to the signal interpretation of the line-integrated signals, with specific application to images from 2D PCI. It is shown that the Fourier components of fluctuations having any non-zero component propagating along the line of sight are not detected. The ramifications of this constraint are discussed, including consideration of the angle between the sight line and flux surface normal. In the experimental geometry, at the point where the flux surfaces are tangent to the sight line, it is shown that it may be possible to detect large poloidally extended (though with small radial wavelength) structures, such as GAMS. The spatial localization technique of this diagnostic is illustrated with experimental data.

  10. Analyzer-based phase-contrast imaging system using a micro focus x-ray source

    SciTech Connect

    Zhou, Wei; Majidi, Keivan; Brankov, Jovan G.

    2014-08-15

    Here we describe a new in-laboratory analyzer based phase contrast-imaging (ABI) instrument using a conventional X-ray tube source (CXS) aimed at bio-medical imaging applications. Phase contrast-imaging allows visualization of soft tissue details usually obscured in conventional X-ray imaging. The ABI system design and major features are described in detail. The key advantage of the presented system, over the few existing CXS ABI systems, is that it does not require high precision components, i.e., CXS, X-ray detector, and electro-mechanical components. To overcome a main problem introduced by these components, identified as temperature stability, the system components are kept at a constant temperature inside of three enclosures, thus minimizing the electrical and mechanical thermal drifts. This is achieved by using thermoelectric (Peltier) cooling/heating modules that are easy to control precisely. For CXS we utilized a microfocus X-ray source with tungsten (W) anode material. In addition the proposed system eliminates tungsten's multiple spectral lines by selecting monochromator crystal size appropriately therefore eliminating need for the costly mismatched, two-crystal monochromator. The system imaging was fine-tuned for tungsten Kα{sub 1} line with the energy of 59.3 keV since it has been shown to be of great clinical significance by a number of researchers at synchrotron facilities. In this way a laboratory system that can be used for evaluating and quantifying tissue properties, initially explored at synchrotron facilities, would be of great interest to a larger research community. To demonstrate the imaging capability of our instrument we use a chicken thigh tissue sample.

  11. Analyzer-based phase-contrast imaging system using a micro focus X-ray source.

    PubMed

    Zhou, Wei; Majidi, Keivan; Brankov, Jovan G

    2014-08-01

    Here we describe a new in-laboratory analyzer based phase contrast-imaging (ABI) instrument using a conventional X-ray tube source (CXS) aimed at bio-medical imaging applications. Phase contrast-imaging allows visualization of soft tissue details usually obscured in conventional X-ray imaging. The ABI system design and major features are described in detail. The key advantage of the presented system, over the few existing CXS ABI systems, is that it does not require high precision components, i.e., CXS, X-ray detector, and electro-mechanical components. To overcome a main problem introduced by these components, identified as temperature stability, the system components are kept at a constant temperature inside of three enclosures, thus minimizing the electrical and mechanical thermal drifts. This is achieved by using thermoelectric (Peltier) cooling/heating modules that are easy to control precisely. For CXS we utilized a microfocus X-ray source with tungsten (W) anode material. In addition the proposed system eliminates tungsten's multiple spectral lines by selecting monochromator crystal size appropriately therefore eliminating need for the costly mismatched, two-crystal monochromator. The system imaging was fine-tuned for tungsten Kα1 line with the energy of 59.3 keV since it has been shown to be of great clinical significance by a number of researchers at synchrotron facilities. In this way a laboratory system that can be used for evaluating and quantifying tissue properties, initially explored at synchrotron facilities, would be of great interest to a larger research community. To demonstrate the imaging capability of our instrument we use a chicken thigh tissue sample. PMID:25173319

  12. Characterization of connective tissue progenitors through phase contrast and multicolor fluorescence time-lapse microscopy

    NASA Astrophysics Data System (ADS)

    Kwee, Edward; Powell, Kimerly; Muschler, George

    2015-03-01

    Connective tissue progenitors (CTPs) are defined as the heterogeneous population of tissue resident stem and progenitor cells capable of proliferating and differentiating into connective tissue phenotypes. The prevalence and variation in clonal progeny of CTPs can be characterized using a colony formation assay. However, colony assays do not directly assess the characteristics of the colony founding CTP. We developed a large field of view, time lapse microscopy system with phase contrast and fluorescence capabilities that enables tracking from seeding through colony formation. Cells derived from the trabecular surface of bone were prepared and seeded in an Ibidi-Ph+ chamber slide. Phase contrast images of the slide were obtained every hour using a DMI6000 Leica microscope, 10X objective, and Retiga 2000R camera. Cells were stained using fluorescent antibodies for multiple markers at the time of plating to determine marker expression on seeded cells and re-stained to determine expression on their progeny. Colonies were identified and characterized using automated image processing and quantitative analysis methods. Following colony identification, the time lapse was reversed to identify and characterize the colony founding CTP according to morphology and marker expression. As a representative example, a CD73+/CD90-/CD105- and a CD73+/CD90+/CD105- CTP resulted in a colony with an area of 3720826 microns2 and percent area expression of 2.98%, 3.62%, and 1.13% for CD73, CD90, and CD105, respectively. This method can be used to study CTPs and other stem and progenitor cell populations to benefit point-of-care methods for assay and isolation in cell based therapies.

  13. Characterization of Mechanical Properties of Tissue Scaffolds by Phase Contrast Imaging and Finite Element Modeling.

    PubMed

    Bawolin, Nahshon K; Dolovich, Allan T; Chen, Daniel X B; Zhang, Chris W J

    2015-08-01

    In tissue engineering, the cell and scaffold approach has shown promise as a treatment to regenerate diseased and/or damaged tissue. In this treatment, an artificial construct (scaffold) is seeded with cells, which organize and proliferate into new tissue. The scaffold itself biodegrades with time, leaving behind only newly formed tissue. The degradation qualities of the scaffold are critical during the treatment period, since the change in the mechanical properties of the scaffold with time can influence cell behavior. To observe in time the scaffold's mechanical properties, a straightforward method is to deform the scaffold and then characterize scaffold deflection accordingly. However, experimentally observing the scaffold deflection is challenging. This paper presents a novel study on characterization of mechanical properties of scaffolds by phase contrast imaging and finite element modeling, which specifically includes scaffold fabrication, scaffold imaging, image analysis, and finite elements (FEs) modeling of the scaffold mechanical properties. The innovation of the work rests on the use of in-line phase contrast X-ray imaging at 20 KeV to characterize tissue scaffold deformation caused by ultrasound radiation forces and the use of the Fourier transform to identify movement. Once deformation has been determined experimentally, it is then compared with the predictions given by the forward solution of a finite element model. A consideration of the number of separate loading conditions necessary to uniquely identify the material properties of transversely isotropic and fully orthotropic scaffolds is also presented, along with the use of an FE as a form of regularization. PMID:25902011

  14. Comparison of subtracted venography and phase contrast in cerebral regions by utilizing 3DT1TFE

    NASA Astrophysics Data System (ADS)

    Heo, Yeong-Cheol; Cho, Jae-Hwan; Jang, Hyon-Chol; Lee, Chang-Hee; Kim, Jung-Su; Lee, Hae-Kag

    2013-06-01

    In this study, we evaluated the 3D venography images and the phase contrast images that were subtracted by using the images that had been obtained before and after utilizing the contrast medium with a 3D, segmented, T1-weighted gradient echo sequence (3DT1TFE) when performing a cerebral magnetic resonance imaging (MRI) examination with contrast medium. The study was carried out in 10 patients who under went a brain examination with a contrast medium by using the 3.0T MR System and 8-channel sensitivity encoding (SENSE) head coil. The 3DT1TFE images after the contrast medium had been used was subtracted from the 3DT1TFE images before the utilization. The subtracted images were re-formed to venography images by using maximum intensity projection (MIP) techniques; then, the re-formed images and 3D phase contrast (PC) venography were evaluated qualitative analysis. The qualitative analysis was done to confirm the reliability of the ratings of the observers via the ICC (intraclass correlation coefficient) and then to evaluate of the statistical significance via an independent T-test. The ICC test showed that 3D PC venography images and subtracted venography images had reliabilities of 0.677 and 0.734 on average, respectively, indicating good reliability of the ratings by the observers. Because the proximal superior sagittal sinus (SSS), the middle SSS, the confluence SSS, the vein of labbe, the internal cerebral vein, and the Vein of Galen represented p > 0.05 a the independent T-test, no statistically significant difference was observed between the two images. However, a significant difference was observed between the images regarding the straight sinus (p < 0.05). As such, the venography images subtracted from the straight sinus would be better, because the average of the straight sinus was higher in subtracted venography.

  15. In vivo imaging of rat cortical bone porosity by synchrotron phase contrast micro computed tomography.

    PubMed

    Pratt, I V; Belev, G; Zhu, N; Chapman, L D; Cooper, D M L

    2015-01-01

    Cortical bone is a dynamic tissue which undergoes adaptive and pathological changes throughout life. Direct longitudinal tracking of this remodeling process holds great promise for improving our understanding of bone development, maintenance and senescence. The application of in vivo micro-computed tomography (micro-CT) has enabled longitudinal tracking of trabecular bone microarchitecture with commercially available scanners generally operating in the 10-20 µm voxel range with absorbed doses reported between 0.5 and 1 Gy. Imaging of cortical bone microarchitecture (porosity) requires higher resolution and thus in vivo imaging of these structures has not been achieved due to excessive radiation dose. In this study we tested the hypothesis that synchrotron propagation phase contrast micro-CT can enable in vivo imaging of cortical porosity in rats at doses comparable to those currently employed for trabecular bone imaging. Synchrotron imaging experiments were conducted at the Canadian Light Source using the bending magnet beamline of the BioMedical Imaging and Therapy (BMIT) facility. Protocol optimization (propagation distance, projection number) was conducted ex vivo on rat (Sprague-Dawley) forelimbs with dose determined by ion chamber and lithium fluoride crystal thermoluminescent dosimeters. Comparative ex vivo imaging was performed using laboratory in vivo scanning systems, identifying a range of doses between 1.2-3.6 Gy for common protocols. A final in vivo synchrotron protocol involving a 2.5 Gy dose was implemented with live rats. The resulting images demonstrated improved delineation of cortical porosity through the improved edge enhancement effect of phase contrast, opening the door to novel experimental studies involving the longitudinal tracking of remodeling. PMID:25489926

  16. In vivo imaging of rat cortical bone porosity by synchrotron phase contrast micro computed tomography

    NASA Astrophysics Data System (ADS)

    Pratt, I. V.; Belev, G.; Zhu, N.; Chapman, L. D.; Cooper, D. M. L.

    2015-01-01

    Cortical bone is a dynamic tissue which undergoes adaptive and pathological changes throughout life. Direct longitudinal tracking of this remodeling process holds great promise for improving our understanding of bone development, maintenance and senescence. The application of in vivo micro-computed tomography (micro-CT) has enabled longitudinal tracking of trabecular bone microarchitecture with commercially available scanners generally operating in the 10-20 µm voxel range with absorbed doses reported between 0.5 and 1 Gy. Imaging of cortical bone microarchitecture (porosity) requires higher resolution and thus in vivo imaging of these structures has not been achieved due to excessive radiation dose. In this study we tested the hypothesis that synchrotron propagation phase contrast micro-CT can enable in vivo imaging of cortical porosity in rats at doses comparable to those currently employed for trabecular bone imaging. Synchrotron imaging experiments were conducted at the Canadian Light Source using the bending magnet beamline of the BioMedical Imaging and Therapy (BMIT) facility. Protocol optimization (propagation distance, projection number) was conducted ex vivo on rat (Sprague-Dawley) forelimbs with dose determined by ion chamber and lithium fluoride crystal thermoluminescent dosimeters. Comparative ex vivo imaging was performed using laboratory in vivo scanning systems, identifying a range of doses between 1.2-3.6 Gy for common protocols. A final in vivo synchrotron protocol involving a 2.5 Gy dose was implemented with live rats. The resulting images demonstrated improved delineation of cortical porosity through the improved edge enhancement effect of phase contrast, opening the door to novel experimental studies involving the longitudinal tracking of remodeling.

  17. Design and characterization of a phase contrast X-ray CT system

    NASA Astrophysics Data System (ADS)

    Zambelli, Joseph N.

    Phase contrast x-ray imaging has recently attracted wide research interest, as it offers the possibility to exploit different contrast mechanisms than conventional absorption imaging, with the potential for higher quality images or more available information as a result. This work details design and construction of au experimental grating-interferometer-based differential phase contrast computed tomography (DPC-CT) imaging system, presents measurements of performance, and compares this new imaging technique with conventional absorption imaging. Details of the fabrication of the specialized x-ray phase and absorption gratings are also provided. This system is unique in that makes use of a conventional rotating-anode x-ray tube, unlike previous designs which were based upon stationary anode x-ray tubes or synchrotron sources. The imaging system described here enables simultaneous reconstruction of electron density, effective atomic number, attenuation coefficient, and small-angle scatter density with data acquired from a single scan. It is theoretically shown and experimentally verified that DPC-CT imaging allows imaging of electron density at high spatial resolution with a much less severe dose penalty compared with conventional absorption imaging. Improved object visibility using electron density imaging is demonstrated with CNR measurements in physical phantoms and comparisons of reconstructions of breast tissue samples. The ability to directly image both electron density and effective atomic number provides a truly quantitative imaging technique and accuracy of the technique is shown using phantoms and potential applications are demonstrated using breast tissue samples. A new reconstruction algorithm which allows a doubling of the diameter of the scanning field of view, a potential enabling technology for eventual clinical use, is also demonstrated.

  18. Ecdysis period of Rhodnius prolixus head investigated using phase contrast synchrotron microtomography.

    PubMed

    Sena, G; Nogueira, L P; Braz, D; Almeida, A P; Gonzalez, M S; Azambuja, P; Colaço, M V; Barroso, R C

    2016-06-01

    Microtomography using synchrotron sources is a useful tool in biological imaging research since the phase coherence of synchrotron beams can be exploited to obtain images with high contrast resolution. This work is part of a series of works using phase contrast synchrotron microtomography in the study of Rhodnius prolixus head, the insect vector of Chagas' disease, responsible for about 12,000 deaths per year. The control of insect vector is the most efficient method to prevent this disease and studies have shown that the use of triflumuron, a chitin synthesis inhibitor, disrupted chitin synthesis during larval development and it's an alternative method against insect pests. The aim of this work was to investigate the biological effects of treatments with triflumuron in the ecdysis period (the moulting of the R. prolixus cuticle) using the new imaging beamline IMX at LNLS (Brazilian Synchrotron Light Laboratory). Nymphs of R. prolixus were taken from the Laboratory of Biochemistry and Physiology of Insects, Oswaldo Cruz Foundation, Brazil. Doses of 0.05mg of triflumuron were applied directly to the abdomen on half of the insects immediately after feeding. The insects were sacrificed 25days after feeding (intermoulting period) and fixed with glutaraldehyde. The results obtained using phase contrast synchrotron microtomography in R. prolixus showed amazing images of the effects of triflumuron on insects in the ecdysis period, and the formation of the new cuticle on those which were not treated with triflumuron. Both formation and malformation of this insect's cuticle have never been seen before with this technique. PMID:27184550

  19. High energy x-ray phase contrast CT using glancing-angle grating interferometers

    SciTech Connect

    Sarapata, A.; Stayman, J. W.; Siewerdsen, J. H.; Finkenthal, M.; Stutman, D.; Pfeiffer, F.

    2014-02-15

    Purpose: The authors present initial progress toward a clinically compatible x-ray phase contrast CT system, using glancing-angle x-ray grating interferometry to provide high contrast soft tissue images at estimated by computer simulation dose levels comparable to conventional absorption based CT. Methods: DPC-CT scans of a joint phantom and of soft tissues were performed in order to answer several important questions from a clinical setup point of view. A comparison between high and low fringe visibility systems is presented. The standard phase stepping method was compared with sliding window interlaced scanning. Using estimated dose values obtained with a Monte-Carlo code the authors studied the dependence of the phase image contrast on exposure time and dose. Results: Using a glancing angle interferometer at high x-ray energy (∼45 keV mean value) in combination with a conventional x-ray tube the authors achieved fringe visibility values of nearly 50%, never reported before. High fringe visibility is shown to be an indispensable parameter for a potential clinical scanner. Sliding window interlaced scanning proved to have higher SNRs and CNRs in a region of interest and to also be a crucial part of a low dose CT system. DPC-CT images of a soft tissue phantom at exposures in the range typical for absorption based CT of musculoskeletal extremities were obtained. Assuming a human knee as the CT target, good soft tissue phase contrast could be obtained at an estimated absorbed dose level around 8 mGy, similar to conventional CT. Conclusions: DPC-CT with glancing-angle interferometers provides improved soft tissue contrast over absorption CT even at clinically compatible dose levels (estimated by a Monte-Carlo computer simulation). Further steps in image processing, data reconstruction, and spectral matching could make the technique fully clinically compatible. Nevertheless, due to its increased scan time and complexity the technique should be thought of not as

  20. Robustness of phase retrieval methods in x-ray phase contrast imaging: A comparison

    SciTech Connect

    Yan, Aimin; Wu, Xizeng; Liu, Hong

    2011-09-15

    Purpose: The robustness of the phase retrieval methods is of critical importance for limiting and reducing radiation doses involved in x-ray phase contrast imaging. This work is to compare the robustness of two phase retrieval methods by analyzing the phase maps retrieved from the experimental images of a phantom. Methods: Two phase retrieval methods were compared. One method is based on the transport of intensity equation (TIE) for phase contrast projections, and the TIE-based method is the most commonly used method for phase retrieval in the literature. The other is the recently developed attenuation-partition based (AP-based) phase retrieval method. The authors applied these two methods to experimental projection images of an air-bubble wrap phantom for retrieving the phase map of the bubble wrap. The retrieved phase maps obtained by using the two methods are compared. Results: In the wrap's phase map retrieved by using the TIE-based method, no bubble is recognizable, hence, this method failed completely for phase retrieval from these bubble wrap images. Even with the help of the Tikhonov regularization, the bubbles are still hardly visible and buried in the cluttered background in the retrieved phase map. The retrieved phase values with this method are grossly erroneous. In contrast, in the wrap's phase map retrieved by using the AP-based method, the bubbles are clearly recovered. The retrieved phase values with the AP-based method are reasonably close to the estimate based on the thickness-based measurement. The authors traced these stark performance differences of the two methods to their different techniques employed to deal with the singularity problem involved in the phase retrievals. Conclusions: This comparison shows that the conventional TIE-based phase retrieval method, regardless if Tikhonov regularization is used or not, is unstable against the noise in the wrap's projection images, while the AP-based phase retrieval method is shown in these

  1. High energy x-ray phase contrast CT using glancing-angle grating interferometers

    PubMed Central

    Sarapata, A.; Stayman, J. W.; Finkenthal, M.; Siewerdsen, J. H.; Pfeiffer, F.; Stutman, D.

    2014-01-01

    Purpose: The authors present initial progress toward a clinically compatible x-ray phase contrast CT system, using glancing-angle x-ray grating interferometry to provide high contrast soft tissue images at estimated by computer simulation dose levels comparable to conventional absorption based CT. Methods: DPC-CT scans of a joint phantom and of soft tissues were performed in order to answer several important questions from a clinical setup point of view. A comparison between high and low fringe visibility systems is presented. The standard phase stepping method was compared with sliding window interlaced scanning. Using estimated dose values obtained with a Monte-Carlo code the authors studied the dependence of the phase image contrast on exposure time and dose. Results: Using a glancing angle interferometer at high x-ray energy (∼45 keV mean value) in combination with a conventional x-ray tube the authors achieved fringe visibility values of nearly 50%, never reported before. High fringe visibility is shown to be an indispensable parameter for a potential clinical scanner. Sliding window interlaced scanning proved to have higher SNRs and CNRs in a region of interest and to also be a crucial part of a low dose CT system. DPC-CT images of a soft tissue phantom at exposures in the range typical for absorption based CT of musculoskeletal extremities were obtained. Assuming a human knee as the CT target, good soft tissue phase contrast could be obtained at an estimated absorbed dose level around 8 mGy, similar to conventional CT. Conclusions: DPC-CT with glancing-angle interferometers provides improved soft tissue contrast over absorption CT even at clinically compatible dose levels (estimated by a Monte-Carlo computer simulation). Further steps in image processing, data reconstruction, and spectral matching could make the technique fully clinically compatible. Nevertheless, due to its increased scan time and complexity the technique should be thought of not as

  2. DESIGN OF A MICROFABRICATED, TWO-ELECTRODE PHASE-CONTRAST ELEMENTSUITABLE FOR ELECTRON MICROSCOPY

    SciTech Connect

    Cambie, Rossana; Downing, Kenneth H.; Typke, Dieter; Glaeser,Robert M.; Jin, Jian

    2006-09-20

    A miniature electrostatic element has been designed to selectively apply a ninety-degree phase shift to the unscattered beam in the back focal plane of the objective lens, in order to realize Zernike-type, in-focus phase contrast in an electron microscope. The design involves a cylindrically shaped, biased-voltage electrode, which is surrounded by a concentric grounded electrode. Electrostatic calculations have been used to determine that the fringing fields in the region of the scattered electron beams will cause a negligible phase shift as long as the ratio of electrode length to the transverse feature-size is greater than 5:1. Unlike the planar, three-electrode einzel lens originally proposed by Boersch for the same purpose, this new design does not require insulating layers to separate the biased and grounded electrodes, and it can thus be produced by a very simple microfabrication process. Scanning electron microscope images confirm that mechanically robust devices with feature sizes of {approx}1 {micro}m can be easily fabricated. Preliminary experimental images demonstrate that these devices do apply a 90-degree phase shift between the scattered and unscattered electrons, as expected.

  3. Phase-contrast zoom tomography reveals precise locations of macrophages in mouse lungs

    NASA Astrophysics Data System (ADS)

    Krenkel, Martin; Markus, Andrea; Bartels, Matthias; Dullin, Christian; Alves, Frauke; Salditt, Tim

    2015-05-01

    We have performed x-ray phase-contrast tomography on mouse lung tissue. Using a divergent x-ray beam generated by nanoscale focusing, we used zoom tomography to produce three-dimensional reconstructions with selectable magnification, resolution, and field of view. Thus, macroscopic tissue samples extending over several mm can be studied in sub-cellular-level structural detail. The zoom capability and, in particular, the high dose efficiency are enabled by the near-perfect exit wavefront of an optimized x-ray waveguide channel. In combination with suitable phase-retrieval algorithms, challenging radiation-sensitive and low-contrast samples can be reconstructed with minimal artefacts. The dose efficiency of the method is demonstrated by the reconstruction of living macrophages both with and without phagocytized contrast agents. We also used zoom tomography to visualize barium-labelled macrophages in the context of morphological structures in asthmatic and healthy mouse lung tissue one day after intratracheal application. The three-dimensional reconstructions showed that the macrophages predominantly localized to the alveoli, but they were also found in bronchial walls, indicating that these cells might be able to migrate from the lumen of the bronchi through the epithelium.

  4. Two-dimensional phase contrast imaging for local turbulence measurements in large helical device (invited)

    SciTech Connect

    Tanaka, K.; Michael, C. A.; Kawahata, K.; Akiyama, T.; Tokuzawa, T.; Vyacheslavov, L. N.; Sanin, A. L.; Okajima, S.

    2008-10-15

    Two-dimensional phase contrast imaging (2D) installed on the large helical device (LHD) is a unique diagnostic for local turbulence measurements. A 10.6 {mu}m infrared CO{sub 2} laser and 6x8 channel HgCdTe 2D detector are used. The length of the scattering volume is larger than plasma size. However, the asymmetry of turbulence structure with respect to the magnetic field and magnetic shear make local turbulence measurements possible. From a 2D image of the integrated fluctuations, the spatial cross-correlation function was estimated using time domain correlation analysis, then, the integrated 2D k-spectrum is obtained using maximum entropy method. The 2D k-spectrum is converted from Cartesian coordinates to cylindrical coordinates. Finally, the angle in cylindrical coordinate is converted to flux surface labels. The fluctuation profile over almost the entire plasma diameter can be obtained at a single moment. The measurable k-region can be varied by adjusting the detection optics. Presently, k=0.1-1.0 mm{sup -1} can be measured which is expected region of ion temperature gradient modes and trapped electron mode in LHD. The spatial resolution is 10%-50% of the minor radius.

  5. Vertical localization of phase contrast imaging diagnostic in Alcator C-Mod

    SciTech Connect

    Lin, L.; Edlund, E. M.; Porkolab, M.; Lin, Y.; Wukitch, S. J.

    2006-10-15

    Phase contrast imaging (PCI) diagnostic has been used to study mode conversion physics of ion cyclotron range of frequency waves [E. Nelson-Melby et al., Phys. Rev. Lett. 90, 155004 (2003)], plasma turbulence [A. Mazurenko et al., Phys. Rev. Lett. 89, 225004 (2002); N. Basse et al., Phys. Plasmas 12, 052512 (2005)], and Alfven Cascades [M. Porkolab et al., IEEE Trans. Plasma Sci. 34, 229 (2006)] in Alcator C-Mod. The C-Mod PCI system measures line integrated electron density fluctuations along 32 vertical chords with a sampling frequency of 10 MHz and wavenumber resolution up to 30 cm{sup -1}. Although PCI normally lacks localization along the chords, the vertical variation of the magnetic field pitch angle allows for localized measurements for large k{sub perpendicular} fluctuations. A system consisting of a partially masked phase plate on a rotatable stage has been installed and quasicoherent modes with wave number {approx}5 cm{sup -1} associated with the enhanced D{alpha}H mode at the top and bottom of the plasma have been differentiated. In future experiments, for k{approx}30 cm{sup -1}, a spatial resolution of r/a{approx}0.3 can be achieved under ideal conditions.

  6. Localized measurement of short wavelength plasma fluctuations with the DIII-D phase contrast imaging diagnostic

    SciTech Connect

    Dorris, J. R.; Rost, J. C.; Porkolab, M.

    2009-02-15

    A novel rotating mask system has been designed and implemented on the DIII-D phase contrast imaging (PCI) diagnostic to produce the first spatially localized PCI measurements of a tokamak plasma. The localization technique makes use of the variation in the magnetic field component perpendicular to the viewing chord as a function of chord height. This new capability provides measurements in the range of 2

  7. Volumetric characterization of human patellar cartilage matrix on phase contrast x-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Abidin, Anas Z.; Nagarajan, Mahesh B.; Checefsky, Walter A.; Coan, Paola; Diemoz, Paul C.; Hobbs, Susan K.; Huber, Markus B.; Wismüller, Axel

    2015-03-01

    Phase contrast X-ray computed tomography (PCI-CT) has recently emerged as a novel imaging technique that allows visualization of cartilage soft tissue, subsequent examination of chondrocyte patterns, and their correlation to osteoarthritis. Previous studies have shown that 2D texture features are effective at distinguishing between healthy and osteoarthritic regions of interest annotated in the radial zone of cartilage matrix on PCI-CT images. In this study, we further extend the texture analysis to 3D and investigate the ability of volumetric texture features at characterizing chondrocyte patterns in the cartilage matrix for purposes of classification. Here, we extracted volumetric texture features derived from Minkowski Functionals and gray-level co-occurrence matrices (GLCM) from 496 volumes of interest (VOI) annotated on PCI-CT images of human patellar cartilage specimens. The extracted features were then used in a machine-learning task involving support vector regression to classify ROIs as healthy or osteoarthritic. Classification performance was evaluated using the area under the receiver operating characteristic (ROC) curve (AUC). The best classification performance was observed with GLCM features correlation (AUC = 0.83 +/- 0.06) and homogeneity (AUC = 0.82 +/- 0.07), which significantly outperformed all Minkowski Functionals (p < 0.05). These results suggest that such quantitative analysis of chondrocyte patterns in human patellar cartilage matrix involving GLCM-derived statistical features can distinguish between healthy and osteoarthritic tissue with high accuracy.

  8. ICRF Mode Conversion Studies with Phase Contrast Imaging and Comparisons with Full-Wave Simulations

    SciTech Connect

    Tsujii, N.; Bonoli, P. T.; Lin, Y.; Wright, J. C.; Wukitch, S. J.; Porkolab, M.; Jaeger, E. F.; Harvey, R. W.

    2011-12-23

    Waves in the ion cyclotron range of frequencies (ICRF) are widely used to heat toka-mak plasmas. In a multi-ion-species plasma, the FW converts to ion cyclotron waves (ICW) and ion Bernstein waves (IBW) around the ion-ion hybrid resonance (mode conversion). The mode converted wave is of interest as an actuator to optimise plasma performance through flow drive and current drive. Numerical simulations are essential to describe these processes accurately, and it is important that these simulation codes be validated. On Alcator C-Mod, direct measurements of the mode converted waves have been performed using Phase Contrast Imaging (PCI), which measures the line-integrated electron density fluctuations. The results were compared to full-wave simulations AORSA and TORIC. AORSA is coupled to a Fokker-Planck code CQL3D for self-consistent simulation of the wave electric field and the minority distribution function. The simulation results are compared to PCI measurements using synthetic diagnostic. The experiments were performed in D-H and D-{sup 3}He plasmas over a wide range of ion species concentrations. The simulations agreed well with the measurements in the strong absorption regime. However, the measured fluctuation intensity was smaller by 1-2 orders of magnitudes in the weakly abosorbing regime, and a realistic description of the plasma edge including dissipation and antenna geometry may be required in these cases.

  9. Pixelated detectors and improved efficiency for magnetic imaging in STEM differential phase contrast.

    PubMed

    Krajnak, Matus; McGrouther, Damien; Maneuski, Dzmitry; Shea, Val O'; McVitie, Stephen

    2016-06-01

    The application of differential phase contrast imaging to the study of polycrystalline magnetic thin films and nanostructures has been hampered by the strong diffraction contrast resulting from the granular structure of the materials. In this paper we demonstrate how a pixelated detector has been used to detect the bright field disk in aberration corrected scanning transmission electron microscopy (STEM) and subsequent processing of the acquired data allows efficient enhancement of the magnetic contrast in the resulting images. Initial results from a charged coupled device (CCD) camera demonstrate the highly efficient nature of this improvement over previous methods. Further hardware development with the use of a direct radiation detector, the Medipix3, also shows the possibilities where the reduction in collection time is more than an order of magnitude compared to the CCD. We show that this allows subpixel measurement of the beam deflection due to the magnetic induction. While the detection and processing is data intensive we have demonstrated highly efficient DPC imaging whereby pixel by pixel interpretation of the induction variation is realised with great potential for nanomagnetic imaging. PMID:27085170

  10. MACROscopic imaging of tumor xenografts using fluorescence, phase contrast, and transmitted light

    NASA Astrophysics Data System (ADS)

    Constantinou, Paul; Nicklee, Trudey; Hedley, David W.; Wilson, Brian C.; Damaskinos, Savvas

    2004-10-01

    Recent advances in imaging technology have contributed greatly to biological science. Confocal fluorescence microscopes (CFM) can acquire 2D and 3D images of biological samples such as live or fixed cells and tissues. Specimens that are large (e.g., a 10 mm x 10 mm tissue section) and overfill the field of view (FOV) of typical microscope objectives require use of image tiling to cover the entire specimen. This can be time consuming and cause artefacts in the composite image. The MACROscope system (Biomedical Photometrics Inc, Waterloo, Canada), is a confocal device with a 22 mm x 70 mm FOV; ideal for imaging large tissue sections in a single frame. The system used here is a prototype capable of simultaneous acquisition from up to three detection channels. Fluorescence images of SiHa mouse tumour xenografts stained with CD31-Cy3, showing blood vessel location, and EF5-Cy5, showing areas of tissue hypoxia, were collected. Differential phase contrast (DPC) images of the same section were also recorded to show tissue morphology. Finally, RGB transmitted light images of human tongue and pancreas tissues were obtained. This new device avoids the need for image tiling and provides simultaneous imaging of multiple fluorescently-labeled tissue specific markers in large biological samples. This enables time- and cost-efficient high-throughput screening of (immuno)histopathological samples. This device may also serve in the imaging of high-throughput DNA and tissue arrays.

  11. Segmenting time-lapse phase contrast images of adjacent NIH 3T3 cells.

    PubMed

    Chalfoun, J; Kociolek, M; Dima, A; Halter, M; Cardone, A; Peskin, A; Bajcsy, P; Brady, M

    2013-01-01

    We present a new method for segmenting phase contrast images of NIH 3T3 fibroblast cells that is accurate even when cells are physically in contact with each other. The problem of segmentation, when cells are in contact, poses a challenge to the accurate automation of cell counting, tracking and lineage modelling in cell biology. The segmentation method presented in this paper consists of (1) background reconstruction to obtain noise-free foreground pixels and (2) incorporation of biological insight about dividing and nondividing cells into the segmentation process to achieve reliable separation of foreground pixels defined as pixels associated with individual cells. The segmentation results for a time-lapse image stack were compared against 238 manually segmented images (8219 cells) provided by experts, which we consider as reference data. We chose two metrics to measure the accuracy of segmentation: the 'Adjusted Rand Index' which compares similarities at a pixel level between masks resulting from manual and automated segmentation, and the 'Number of Cells per Field' (NCF) which compares the number of cells identified in the field by manual versus automated analysis. Our results show that the automated segmentation compared to manual segmentation has an average adjusted rand index of 0.96 (1 being a perfect match), with a standard deviation of 0.03, and an average difference of the two numbers of cells per field equal to 5.39% with a standard deviation of 4.6%. PMID:23126432

  12. X-ray phase contrast with injected gas for tumor microangiography

    NASA Astrophysics Data System (ADS)

    Lundström, U.; Westermark, U. K.; Larsson, D. H.; Burvall, A.; Arsenian Henriksson, M.; Hertz, H. M.

    2014-06-01

    We show that the microvasculature of mouse tumors can be visualized using propagation-based phase-contrast x-ray imaging with gas as the contrast agent. The large density difference over the gas-tissue interface provides high contrast, allowing the imaging of small-diameter blood vessels with relatively short exposure times and low dose using a compact liquid-metal-jet x-ray source. The method investigated is applied to tumors (E1A/Ras-transformed mouse embryonic fibroblasts) grown in mouse ears, demonstrating sub-15-µm-diameter imaging of their blood vessels. The exposure time for a 2D projection image is a few seconds and a full tomographic 3D map takes some minutes. The method relies on the strength of the vasculature to withstand the gas pressure. Given that tumor vessels are known to be more fragile than normal vessels, we investigate the tolerance of the vasculature of 12 tumors to gas injection and find that a majority withstand 200 mbar pressures, enough to fill 12-µm-diameter vessels with gas. A comparison of the elasticity of tumorous and non-tumorous vessels supports the assumption of tumor vessels being more fragile. Finally, we conclude that the method has the potential to be extended to the imaging of 15 µm vessels in thick tissue, including mouse imaging, making it of interest for, e.g., angiogenesis research.

  13. Schlieren, Phase-Contrast, and Spectroscopy Diagnostics for the LBNL HIF Plasma Channel Experiment

    NASA Astrophysics Data System (ADS)

    Ponce, D. M.; Niemann, C.; Fessenden, T. J.; Leemans, W.; Vandersloot, K.; Dahlbacka, G.; Yu, S. S.; Sharp, W. M.; Tauschwitz, A.

    1999-11-01

    The LBNL Plasma Channel experiment has demonstrated stable 42-cm Z-pinch discharge plasma channels with peak currents in excess of 50 kA for a 7 torr nitrogen, 30 kV discharge. These channels offer the possibility of transporting heavy-ion beams for inertial fusion. We postulate that the stability of these channels resides in the existance of a neutral-gas density depresion created by a pre-pulse discharge before the main capacitor bank discharge is created. Here, we present the results and experimental diagnostics setup used for the study of the pre-pulse and main bank channels. Observation of both the plasma and neutral gas dynamics is achieved. Schlieren, Zernike's phase-contrast, and spectroscopic techniques are used. Preliminary Schlieren results show a gas shockwave moving radially at a rate of ≈ 10^6 mm/sec as a result of the fast and localized deposited energy during the evolution of the pre-pulse channel. This data will be used to validate simulation codes (BUCKY and CYCLOPS).

  14. Laser-wakefield accelerators for medical phase contrast imaging: Monte Carlo simulations and experimental studies

    NASA Astrophysics Data System (ADS)

    Cipiccia, S.; Reboredo, D.; Vittoria, Fabio A.; Welsh, G. H.; Grant, P.; Grant, D. W.; Brunetti, E.; Wiggins, S. M.; Olivo, A.; Jaroszynski, D. A.

    2015-05-01

    X-ray phase contrast imaging (X-PCi) is a very promising method of dramatically enhancing the contrast of X-ray images of microscopic weakly absorbing objects and soft tissue, which may lead to significant advancement in medical imaging with high-resolution and low-dose. The interest in X-PCi is giving rise to a demand for effective simulation methods. Monte Carlo codes have been proved a valuable tool for studying X-PCi including coherent effects. The laser-plasma wakefield accelerators (LWFA) is a very compact particle accelerator that uses plasma as an accelerating medium. Accelerating gradient in excess of 1 GV/cm can be obtained, which makes them over a thousand times more compact than conventional accelerators. LWFA are also sources of brilliant betatron radiation, which are promising for applications including medical imaging. We present a study that explores the potential of LWFA-based betatron sources for medical X-PCi and investigate its resolution limit using numerical simulations based on the FLUKA Monte Carlo code, and present preliminary experimental results.

  15. Synchrotron-based phase-contrast images of zebrafish and its anatomical structures

    NASA Astrophysics Data System (ADS)

    Rao Donepudi, Venkateswara; Melumai, Bhaskaraiah; Thallapaka, Balasaidulu; Sandeep, Konam; Cesareo, Roberto; Brunetti, Antonio; Zhong, Zhong; Akatsuka, Takao; Yuasa, Tetsuya; Takeda, Tohoru; Gigante, Giovanni E.

    2014-08-01

    Images of vertebrates (zebrafish and zebrafish eye) have been obtained by using an X-ray phase-contrast imaging technique, namely, synchrotron-based diffraction-enhanced imaging (SY-DEI) (or analyzer based imaging) and synchrotron-based diffraction imaging in tomography mode (SY-DEI-CT). Due to the limitations of the conventional radiographic imaging in visualizing the internal complex feature of the sample, we utilized the upgraded SY-DEI and SY-DEI-CT systems to acquire the images at 20, 30 and 40 keV, to observe the enhanced contrast. SY-DEI and SY-DEI-CT techniques exploits the refraction properties, and have great potential in studies of soft biological tissues, in particular for low (Z) elements, such as, C, H, O and N, which constitutes the soft tissue. Recently, these techniques are characterized by its extraordinary image quality, with improved contrast, by imaging invertebrates. We have chosen the vertebrate sample of zebrafish (Danio rerio), a model organism widely used in developmental biology and oncology. For biological imaging, these techniques are most sensitive to enhance the contrast. For the present study, images of the sample, in planar and tomography modes offer more clarity on the contrast enhancement of anatomical features of the eye, especially the nerve bundle, swim bladder, grills and some internal organs in gut with more visibility.

  16. Feasibility of using energy-resolving detectors in differential phase-contrast imaging

    NASA Astrophysics Data System (ADS)

    Baturin, Pavlo

    2016-03-01

    In a common clinical setting, conventional absorption-based imaging provides relatively good contrast between bonelike and soft-tissue materials. The reliability of material differentiation, however, is hampered when materials with similar absorption properties are scanned. This problem can be addressed by utilizing a spectral imaging technique whereby multiple X-ray measurements are taken at different beam conditions. In this work, we discuss the possibility of using a spectral imaging approach in a grating-based, differential-phase contrast-imaging (DPCI) modality. Two approaches, dual exposure with a conventional flat-panel detector (FPD) and a single exposure with a photon-counting energy-resolving detector (PCD), were reviewed. The feasibility of a single-exposure DPCI and a two-bin PCD setup was assessed quantitatively by a least-squares minimization algorithm applied to an X-ray diffraction pattern. It was shown that a two-peak-shaped X-ray spectrum can allow PCDs to be placed unambiguously at single Talbot distances making it possible to simultaneously detect photons in each energy bin with comparable efficiencies. The results of this work can help build a bridge between two rapidly developing imaging modalities, X-ray spectral imaging and X-ray DPCI.

  17. Correction of data truncation artifacts in differential phase contrast (DPC) tomosynthesis imaging

    NASA Astrophysics Data System (ADS)

    Garrett, John; Ge, Yongshuai; Li, Ke; Chen, Guang-Hong

    2015-10-01

    The use of grating based Talbot-Lau interferometry permits the acquisition of differential phase contrast (DPC) imaging with a conventional medical x-ray source and detector. However, due to the limited area of the gratings, limited area of the detector, or both, data truncation image artifacts are often observed in tomographic DPC acquisitions and reconstructions, such as tomosynthesis (limited-angle tomography). When data are truncated in the conventional x-ray absorption tomosynthesis imaging, a variety of methods have been developed to mitigate the truncation artifacts. However, the same strategies used to mitigate absorption truncation artifacts do not yield satisfactory reconstruction results in DPC tomosynthesis reconstruction. In this work, several new methods have been proposed to mitigate data truncation artifacts in a DPC tomosynthesis system. The proposed methods have been validated using experimental data of a mammography accreditation phantom, a bovine udder, as well as several human cadaver breast specimens using a bench-top DPC imaging system at our facility.

  18. Rule-based fuzzy vector median filters for 3D phase contrast MRI segmentation

    NASA Astrophysics Data System (ADS)

    Sundareswaran, Kartik S.; Frakes, David H.; Yoganathan, Ajit P.

    2008-02-01

    Recent technological advances have contributed to the advent of phase contrast magnetic resonance imaging (PCMRI) as standard practice in clinical environments. In particular, decreased scan times have made using the modality more feasible. PCMRI is now a common tool for flow quantification, and for more complex vector field analyses that target the early detection of problematic flow conditions. Segmentation is one component of this type of application that can impact the accuracy of the final product dramatically. Vascular segmentation, in general, is a long-standing problem that has received significant attention. Segmentation in the context of PCMRI data, however, has been explored less and can benefit from object-based image processing techniques that incorporate fluids specific information. Here we present a fuzzy rule-based adaptive vector median filtering (FAVMF) algorithm that in combination with active contour modeling facilitates high-quality PCMRI segmentation while mitigating the effects of noise. The FAVMF technique was tested on 111 synthetically generated PC MRI slices and on 15 patients with congenital heart disease. The results were compared to other multi-dimensional filters namely the adaptive vector median filter, the adaptive vector directional filter, and the scalar low pass filter commonly used in PC MRI applications. FAVMF significantly outperformed the standard filtering methods (p < 0.0001). Two conclusions can be drawn from these results: a) Filtering should be performed after vessel segmentation of PC MRI; b) Vector based filtering methods should be used instead of scalar techniques.

  19. A consideration of the signal-to-noise ratio in phase contrast mammography

    NASA Astrophysics Data System (ADS)

    Kato, Yuri; Fujita, Naotoshi; Kodera, Yoshie

    2010-04-01

    Recently, with developments in medicine, digital systems such as computed radiography (CR) and flat-panel detector (FPD) systems are being employed for mammography instead of analog systems such as the screen-film system. Phase-contrast mammography (PCM) is a commercially available digital system that uses images with a magnification of 1.75x. To study the effect of the air gap in PCM, we measured the scatter fraction ratio (SFR) and calculated the signal-to-noise ratio (SNR) in PCM, and compared it to that in conventional mammography (CM). Then, to extend the SNR to the spatial frequency domain, we calculated the noise equivalent quanta (NEQ) and detective quantum efficiency (DQE) used by the modulation transfer function (MTF), noise power spectrum of the pixel value (NPSΔPV), gradient of the digital characteristic curve, and number of X-ray photons. The obtained results indicated that the SFR of the PCM was as low as that of the CM with a grid. When the exposure dose was constant, the SNR of the PCM was the highest in all systems. Moreover, the NEQ and DQE for the PCM were higher than those for the CM (G-) in the spatial frequency domain over 2.5 cycles/mm. These results showed that the number of scattered X-rays was reduced sufficiently by the air gap in the PCM and the NEQ and DQE for PCM were influenced by the presampled MTF in the high-spatial-frequency domain.

  20. Measurements of Short Wavelength Plasma Fluctuations Using the DIII-D Phase Contrast Imaging Diagnostic

    NASA Astrophysics Data System (ADS)

    Dorris, J. R.; Rost, J. C.; Porkolab, M.; Burrell, K. H.

    2010-11-01

    The DIII-D Phase Contrast Imaging (PCI) diagnostic has been upgraded and used to measure turbulence in the outer plasma region (0.7 < r/a < 1) covering an operational range of 10 kHz through 10 MHz and 2-30 cm-1. A novel rotating mask has been used to measure turbulence as a function of propagation angle about the PCI chord. This technique provides localized measurements along the PCI chord for turbulence with k˜0, and an estimate of the turbulence k value otherwise. Long wavelength (|k|<˜12 cm-1) turbulence is localized to within the instrumental width of the last closed flux surface (LCFS) (r/a>˜0.9). Modes with finite (and theoretically unexpected) parallel wavenumber have been seen to propagate at angles as large as k/k ˜0.1-0.4. Due to the finite k, these modes cannot be localized with the present techniques. A theoretical explanation for these modes is lacking at the present time.

  1. Localized measurement of short wavelength plasma fluctuations with the DIII-D phase contrast imaging diagnostic

    NASA Astrophysics Data System (ADS)

    Dorris, J. R.; Rost, J. C.; Porkolab, M.

    2009-02-01

    A novel rotating mask system has been designed and implemented on the DIII-D phase contrast imaging (PCI) diagnostic to produce the first spatially localized PCI measurements of a tokamak plasma. The localization technique makes use of the variation in the magnetic field component perpendicular to the viewing chord as a function of chord height. This new capability provides measurements in the range of 2

  2. Comparison of DIII-D Phase Contrast Imaging Measurements in the Edge and Core Regions

    NASA Astrophysics Data System (ADS)

    Rost, C. J.; Burrell, K. H.

    2005-10-01

    During the last DIII-D run period, the phase contrast imaging (PCI) turbulence diagnostic acquired data in an upgraded configuration. The improvements include 10 MHz digitizers with a data record covering the entire discharge and a wavenumber range increased to 30/cm. The beampath was previously tangent to the LCFS but now passes through the LCFS and reaches r/a=0.8. The PCI was previously sensitive only to radial modes, but it is now sensitive to modes with finite poloidal wavenumber. Measurements of turbulence near the ITG range, particularly the S(k,f) spectra, now show a Doppler shift that was never observed previously. Analysis of this new data includes the variation of the magnetic field along the beam path. Comparisons with previous PCI measurements in the old beam geometry give us a more complete picture of the edge turbulence. The increased wavenumber range also allows us to examine how experimental frequency spectra of plasma turbulence depend on the wavenumber range of the diagnostic.

  3. A Combined Phase Contrast Imaging-Interferometer System for the Detection of Multiscale Electron Density Fluctuations

    NASA Astrophysics Data System (ADS)

    Davis, E. M.; Rost, J. C.; Porkolab, M.; Marinoni, A.

    2014-10-01

    ITER and next-step devices will have harsh neutron environment and limited port space, severely restricting many crucial plasma diagnostics. As such, it is essential that we develop robust diagnostics with minimal access restrictions, small port requirements, and high spatiotemporal bandwidths. DIII-D's Phase Contrast Imaging (PCI) system is a model of such a burning plasma diagnostic, using a 10.6 μ m laser to measure ∫ñe dl at 10 kHz < f < 10 MHz and 1.5 cm-1 < k < 30 cm-1. To eliminate PCI's low- k cutoff, we have designed and are constructing a traditional interferometer along the existing PCI beam path, extending the minimum detectable k to 0 cm-1. The combined PCI-interferometer uses a single 10.6 μ m beam, two interference schemes, and two detectors to make the relevant measurements. In addition to diagnostic proof-of-principle, the combined PCI-interferometer's improved bandwidth will aid model validation and allow measurement of low and high n MHD modes. Initial results will be discussed. Work supported by the US DOE under DE-FG02-94ER54235, DE-FC02-04ER54698, DE-FC02-99ER54512, and NNSA SSGF.

  4. Ex vivo differential phase contrast and magnetic resonance imaging for characterization of human carotid atherosclerotic plaques.

    PubMed

    Meletta, Romana; Borel, Nicole; Stolzmann, Paul; Astolfo, Alberto; Klohs, Jan; Stampanoni, Marco; Rudin, Markus; Schibli, Roger; Krämer, Stefanie D; Herde, Adrienne Müller

    2015-10-01

    Non-invasive detection of specific atherosclerotic plaque components related to vulnerability is of high clinical relevance to prevent cerebrovascular events. The feasibility of magnetic resonance imaging (MRI) for characterization of plaque components was already demonstrated. We aimed to evaluate the potential of ex vivo differential phase contrast X-ray tomography (DPC) to accurately characterize human carotid plaque components in comparison to high field multicontrast MRI and histopathology. Two human plaque segments, obtained from carotid endarterectomy, classified according to criteria of the American Heart Association as stable and unstable plaque, were examined by ex vivo DPC tomography and multicontrast MRI (T1-, T2-, and proton density-weighted imaging, magnetization transfer contrast, diffusion-weighted imaging). To identify specific plaque components, the plaques were subsequently sectioned and stained for fibrous and cellular components, smooth muscle cells, hemosiderin, and fibrin. Histological data were then matched with DPC and MR images to define signal criteria for atherosclerotic plaque components. Characteristic structures, such as the lipid and necrotic core covered by a fibrous cap, calcification and hemosiderin deposits were delineated by histology and found with excellent sensitivity, resolution and accuracy in both imaging modalities. DPC tomography was superior to MRI regarding resolution and soft tissue contrast. Ex vivo DPC tomography allowed accurate identification of structures and components of atherosclerotic plaques at different lesion stages, in good correlation with histopathological findings. PMID:26179860

  5. X-ray phase contrast with injected gas for tumor microangiography.

    PubMed

    Lundström, U; Westermark, U K; Larsson, D H; Burvall, A; Arsenian Henriksson, M; Hertz, H M

    2014-06-01

    We show that the microvasculature of mouse tumors can be visualized using propagation-based phase-contrast x-ray imaging with gas as the contrast agent. The large density difference over the gas-tissue interface provides high contrast, allowing the imaging of small-diameter blood vessels with relatively short exposure times and low dose using a compact liquid-metal-jet x-ray source. The method investigated is applied to tumors (E1A/Ras-transformed mouse embryonic fibroblasts) grown in mouse ears, demonstrating sub-15-µm-diameter imaging of their blood vessels. The exposure time for a 2D projection image is a few seconds and a full tomographic 3D map takes some minutes. The method relies on the strength of the vasculature to withstand the gas pressure. Given that tumor vessels are known to be more fragile than normal vessels, we investigate the tolerance of the vasculature of 12 tumors to gas injection and find that a majority withstand 200 mbar pressures, enough to fill 12-µm-diameter vessels with gas. A comparison of the elasticity of tumorous and non-tumorous vessels supports the assumption of tumor vessels being more fragile. Finally, we conclude that the method has the potential to be extended to the imaging of 15 µm vessels in thick tissue, including mouse imaging, making it of interest for, e.g., angiogenesis research. PMID:24801363

  6. Spatial resolution characterization of differential phase contrast CT systems via modulation transfer function (MTF) measurements

    NASA Astrophysics Data System (ADS)

    Li, Ke; Zambelli, Joseph; Bevins, Nicholas; Ge, Yongshuai; Chen, Guang-Hong

    2013-06-01

    By adding a Talbot-Lau interferometer to a conventional x-ray absorption computed tomography (CT) imaging system, both differential phase contrast (DPC) signal and absorption contrast signal can be simultaneously measured from the same set of CT measurements. The imaging performance of such multi-contrast x-ray CT imaging systems can be characterized with standard metrics such as noise variance, noise power spectrum, contrast-to-noise ratio, modulation transfer function (MTF), and task-based detectability index. Among these metrics, the measurement of the MTF can be challenging in DPC-CT systems due to several confounding factors such as phase wrapping and the difficulty of using fine wires as probes. To address these technical challenges, this paper discusses a viable and reliable method to experimentally measure the MTF of DPC-CT. It has been found that the spatial resolution of DPC-CT is degraded, when compared to that of the corresponding absorption CT, due to the presence of a source grating G0 in the Talbot-Lau interferometer. An effective MTF was introduced and experimentally estimated to describe the impact of the Talbot-Lau interferometer on the system MTF.

  7. Spatial resolution characterization of differential phase contrast CT systems via modulation transfer function (MTF) measurements.

    PubMed

    Li, Ke; Zambelli, Joseph; Bevins, Nicholas; Ge, Yongshuai; Chen, Guang-Hong

    2013-06-21

    By adding a Talbot-Lau interferometer to a conventional x-ray absorption computed tomography (CT) imaging system, both differential phase contrast (DPC) signal and absorption contrast signal can be simultaneously measured from the same set of CT measurements. The imaging performance of such multi-contrast x-ray CT imaging systems can be characterized with standard metrics such as noise variance, noise power spectrum, contrast-to-noise ratio, modulation transfer function (MTF), and task-based detectability index. Among these metrics, the measurement of the MTF can be challenging in DPC-CT systems due to several confounding factors such as phase wrapping and the difficulty of using fine wires as probes. To address these technical challenges, this paper discusses a viable and reliable method to experimentally measure the MTF of DPC-CT. It has been found that the spatial resolution of DPC-CT is degraded, when compared to that of the corresponding absorption CT, due to the presence of a source grating G0 in the Talbot-Lau interferometer. An effective MTF was introduced and experimentally estimated to describe the impact of the Talbot-Lau interferometer on the system MTF. PMID:23685949

  8. X-ray phase contrast imaging of calcified tissue and biomaterial structure in bioreactor engineered tissues.

    PubMed

    Appel, Alyssa A; Larson, Jeffery C; Garson, Alfred B; Guan, Huifeng; Zhong, Zhong; Nguyen, Bao-Ngoc B; Fisher, John P; Anastasio, Mark A; Brey, Eric M

    2015-03-01

    Tissues engineered in bioreactor systems have been used clinically to replace damaged tissues and organs. In addition, these systems are under continued development for many tissue engineering applications. The ability to quantitatively assess material structure and tissue formation is critical for evaluating bioreactor efficacy and for preimplantation assessment of tissue quality. Techniques that allow for the nondestructive and longitudinal monitoring of large engineered tissues within the bioreactor systems will be essential for the translation of these strategies to viable clinical therapies. X-ray Phase Contrast (XPC) imaging techniques have shown tremendous promise for a number of biomedical applications owing to their ability to provide image contrast based on multiple X-ray properties, including absorption, refraction, and scatter. In this research, mesenchymal stem cell-seeded alginate hydrogels were prepared and cultured under osteogenic conditions in a perfusion bioreactor. The constructs were imaged at various time points using XPC microcomputed tomography (µCT). Imaging was performed with systems using both synchrotron- and tube-based X-ray sources. XPC µCT allowed for simultaneous three-dimensional (3D) quantification of hydrogel size and mineralization, as well as spatial information on hydrogel structure and mineralization. Samples were processed for histological evaluation and XPC showed similar features to histology and quantitative analysis consistent with the histomorphometry. These results provide evidence of the significant potential of techniques based on XPC for noninvasive 3D imaging engineered tissues grown in bioreactors. PMID:25257802

  9. X-ray Phase Contrast Imaging of Calcified Tissue and Biomaterial Structure in Bioreactor Engineered Tissues

    SciTech Connect

    Appel, Alyssa A.; Larson, Jeffery C.; Garson, III, Alfred B.; Guan, Huifeng; Zhong, Zhong; Nguyen, Bao-Ngoc; Fisher, John P.; Anastasio, Mark A.; Brey, Eric M.

    2014-11-04

    Tissues engineered in bioreactor systems have been used clinically to replace damaged tissues and organs. In addition, these systems are under continued development for many tissue engineering applications. The ability to quantitatively assess material structure and tissue formation is critical for evaluating bioreactor efficacy and for preimplantation assessment of tissue quality. These techniques allow for the nondestructive and longitudinal monitoring of large engineered tissues within the bioreactor systems and will be essential for the translation of these strategies to viable clinical therapies. X-ray Phase Contrast (XPC) imaging techniques have shown tremendous promise for a number of biomedical applications owing to their ability to provide image contrast based on multiple X-ray properties, including absorption, refraction, and scatter. In this research, mesenchymal stem cell-seeded alginate hydrogels were prepared and cultured under osteogenic conditions in a perfusion bioreactor. The constructs were imaged at various time points using XPC microcomputed tomography (µCT). Imaging was performed with systems using both synchrotron- and tube-based X-ray sources. XPC µCT allowed for simultaneous three-dimensional (3D) quantification of hydrogel size and mineralization, as well as spatial information on hydrogel structure and mineralization. Samples were processed for histological evaluation and XPC showed similar features to histology and quantitative analysis consistent with the histomorphometry. Furthermore, these results provide evidence of the significant potential of techniques based on XPC for noninvasive 3D imaging engineered tissues grown in bioreactors.

  10. High-throughput 3D tracking of bacteria on a standard phase contrast microscope

    NASA Astrophysics Data System (ADS)

    Taute, K. M.; Gude, S.; Tans, S. J.; Shimizu, T. S.

    2015-11-01

    Bacteria employ diverse motility patterns in traversing complex three-dimensional (3D) natural habitats. 2D microscopy misses crucial features of 3D behaviour, but the applicability of existing 3D tracking techniques is constrained by their performance or ease of use. Here we present a simple, broadly applicable, high-throughput 3D bacterial tracking method for use in standard phase contrast microscopy. Bacteria are localized at micron-scale resolution over a range of 350 × 300 × 200 μm by maximizing image cross-correlations between their observed diffraction patterns and a reference library. We demonstrate the applicability of our technique to a range of bacterial species and exploit its high throughput to expose hidden contributions of bacterial individuality to population-level variability in motile behaviour. The simplicity of this powerful new tool for bacterial motility research renders 3D tracking accessible to a wider community and paves the way for investigations of bacterial motility in complex 3D environments.

  11. Generalized phase contrast-enhanced diffractive coupling to light-driven microtools

    NASA Astrophysics Data System (ADS)

    Villangca, Mark; Bañas, Andrew; Palima, Darwin; Glückstad, Jesper

    2015-11-01

    We have previously demonstrated on-demand dynamic coupling to optically manipulated microtools coined as wave-guided optical waveguides using diffractive techniques on a "point and shoot" approach. These microtools are extended microstructures fabricated using two-photon photopolymerization and function as free-floating optically trapped waveguides. Dynamic coupling of focused light via these structures being moved in three-dimensional space is done holographically. However, calculating the necessary holograms is not straightforward when using counter-propagating trapping geometry. The generation of the coupling spots is done in real time following the position of each microtool with the aid of an object tracking routine. This approach allows continuous coupling of light through the microtools which can be useful in a variety of biophotonics applications. To complement the targeted-light delivery capability of the microtools, the applied spatial light modulator has been illuminated with a properly matched input beam cross section based on the generalized phase contrast method. Our results show a significant gain in the output at the tip of each microtool as measured from the fluorescence signal of the trapping medium. The ability to switch from on-demand to continuous addressing with efficient illumination leverages our microtools for potential applications in stimulation and near-field-based biophotonics on cellular scales.

  12. Virtual unrolling and deciphering of Herculaneum papyri by X-ray phase-contrast tomography

    PubMed Central

    Bukreeva, I.; Mittone, A.; Bravin, A.; Festa, G.; Alessandrelli, M.; Coan, P.; Formoso, V.; Agostino, R. G.; Giocondo, M.; Ciuchi, F.; Fratini, M.; Massimi, L.; Lamarra, A.; Andreani, C.; Bartolino, R.; Gigli, G.; Ranocchia, G.; Cedola, A.

    2016-01-01

    A collection of more than 1800 carbonized papyri, discovered in the Roman ‘Villa dei Papiri’ at Herculaneum is the unique classical library survived from antiquity. These papyri were charred during 79 A.D. Vesuvius eruption, a circumstance which providentially preserved them until now. This magnificent collection contains an impressive amount of treatises by Greek philosophers and, especially, Philodemus of Gadara, an Epicurean thinker of 1st century BC. We read many portions of text hidden inside carbonized Herculaneum papyri using enhanced X-ray phase-contrast tomography non-destructive technique and a new set of numerical algorithms for ‘virtual-unrolling’. Our success lies in revealing the largest portion of Greek text ever detected so far inside unopened scrolls, with unprecedented spatial resolution and contrast, all without damaging these precious historical manuscripts. Parts of text have been decoded and the ‘voice’ of the Epicurean philosopher Philodemus is brought back again after 2000 years from Herculaneum papyri. PMID:27265417

  13. Towards x-ray differential phase contrast imaging on a compact setup

    NASA Astrophysics Data System (ADS)

    Thüring, T.; Modregger, P.; Pinzer, B. R.; Wang, Z.; Rutishauser, S.; David, C.; Grund, T.; Kenntner, J.; Stampanoni, M.

    2011-03-01

    A new imaging setup, aimed to perform differential X-ray phase contrast (DPC) imaging with a Talbot interferometer on a microfocus X-ray tube, is demonstrated. The main features compared to recently proposed setups are an extremely short source to detector distance, high spatial resolution and a large field of view. The setup is designed for an immediate integration into a industrial micro CT scanner. In this paper, technical challenges of a compact setup, namely the critical source coherence and divergence, are discussed. A theoretical analysis using wave optics based computer simulations is performed to estimate the DPC signal visibility and the size of the field of view for a given setup geometry. The maximization of the signal visibility as a function of the inter-grating distance yields the optimal grating parameters. Imaging results using the optimized grating parameters are presented. The reduction of the field of view, being a consequence of the high beam divergence, was solved by fabricating new, cylindrically bent diffraction gratings. The fabrication process of these gratings required a change of the currently used wafer materials and an adaption of the manufacturing techniques. The implementation of the new setup represents a major step forward for the industrial application of the DPC technique.

  14. X-ray Phase Contrast Allows Three Dimensional, Quantitative Imaging of Hydrogel Implants.

    PubMed

    Appel, Alyssa A; Larson, Jeffery C; Jiang, Bin; Zhong, Zhong; Anastasio, Mark A; Brey, Eric M

    2016-03-01

    Three dimensional imaging techniques are needed for the evaluation and assessment of biomaterials used for tissue engineering and drug delivery applications. Hydrogels are a particularly popular class of materials for medical applications but are difficult to image in tissue using most available imaging modalities. Imaging techniques based on X-ray Phase Contrast (XPC) have shown promise for tissue engineering applications due to their ability to provide image contrast based on multiple X-ray properties. In this manuscript, we investigate the use of XPC for imaging a model hydrogel and soft tissue structure. Porous fibrin loaded poly(ethylene glycol) hydrogels were synthesized and implanted in a rodent subcutaneous model. Samples were explanted and imaged with an analyzer-based XPC technique and processed and stained for histology for comparison. Both hydrogel and soft tissues structures could be identified in XPC images. Structure in skeletal muscle adjacent could be visualized and invading fibrovascular tissue could be quantified. There were no differences between invading tissue measurements from XPC and the gold-standard histology. These results provide evidence of the significant potential of techniques based on XPC for 3D imaging of hydrogel structure and local tissue response. PMID:26487123

  15. Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry

    DOE PAGESBeta

    Ophus, Colin; Ciston, Jim; Pierce, Jordan; Harvey, Tyler R.; Chess, Jordan; McMorran, Benjamin J.; Czarnik, Cory; Rose, Harald H.; Ercius, Peter

    2016-02-29

    The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, makingmore » it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Ultimately, simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals.« less

  16. X-ray micro-beam techniques and phase contrast tomography applied to biomaterials

    NASA Astrophysics Data System (ADS)

    Fratini, Michela; Campi, Gaetano; Bukreeva, Inna; Pelliccia, Daniele; Burghammer, Manfred; Tromba, Giuliana; Cancedda, Ranieri; Mastrogiacomo, Maddalena; Cedola, Alessia

    2015-12-01

    A deeper comprehension of the biomineralization (BM) process is at the basis of tissue engineering and regenerative medicine developments. Several in-vivo and in-vitro studies were dedicated to this purpose via the application of 2D and 3D diagnostic techniques. Here, we develop a new methodology, based on different complementary experimental techniques (X-ray phase contrast tomography, micro-X-ray diffraction and micro-X-ray fluorescence scanning technique) coupled to new analytical tools. A qualitative and quantitative structural investigation, from the atomic to the micrometric length scale, is obtained for engineered bone tissues. The high spatial resolution achieved by X-ray scanning techniques allows us to monitor the bone formation at the first-formed mineral deposit at the organic-mineral interface within a porous scaffold. This work aims at providing a full comprehension of the morphology and functionality of the biomineralization process, which is of key importance for developing new drugs for preventing and healing bone diseases and for the development of bio-inspired materials.

  17. Quantitative X-ray phase contrast waveguide imaging of bacterial endospores1

    PubMed Central

    Wilke, R. N.; Hoppert, M.; Krenkel, M.; Bartels, M.; Salditt, T.

    2015-01-01

    Quantitative waveguide-based X-ray phase contrast imaging has been carried out on the level of single, unstained, unsliced and freeze-dried bacterial cells of Bacillus thuringiensis and Bacillus subtilis using hard X-rays of 7.9 keV photon energy. The cells have been prepared in the metabolically dormant state of an endospore. The quantitative phase maps obtained by iterative phase retrieval using a modified hybrid input–output algorithm allow for mass and mass density determinations on the level of single individual endospores but include also large field of view investigations. Additionally, a direct reconstruction based on the contrast transfer function is investigated, and the two approaches are compared. Depending on the field of view and method, a resolution down to 65 nm was achieved at a maximum applied dose of below 5 × 105 Gy. Masses in the range of about ∼110–190 (20) fg for isolated endospores have been obtained. PMID:25844079

  18. Spatial resolution characterization of differential phase contrast CT systems via modulation transfer function (MTF) measurements

    PubMed Central

    Li, Ke; Zambelli, Joseph; Bevins, Nicholas; Ge, Yongshuai; Chen, Guang-Hong

    2013-01-01

    By adding a Talbot–Lau interferometer to a conventional x-ray absorption computed tomography (CT) imaging system, both differential phase contrast (DPC) signal and absorption contrast signal can be simultaneously measured from the same set of CT measurements. The imaging performance of such multi-contrast x-ray CT imaging systems can be characterized with standard metrics such as noise variance, noise power spectrum, contrast-to-noise ratio, modulation transfer function (MTF), and task-based detectability index. Among these metrics, the measurement of the MTF can be challenging in DPC-CT systems due to several confounding factors such as phase wrapping and the difficulty of using fine wires as probes. To address these technical challenges, this paper discusses a viable and reliable method to experimentally measure the MTF of DPC-CT. It has been found that the spatial resolution of DPC-CT is degraded, when compared to that of the corresponding absorption CT, due to the presence of a source grating G0 in the Talbot-Lau interferometer. An effective MTF was introduced and experimentally estimated to describe the impact of the Talbot–Lau interferometer on the system MTF. PMID:23685949

  19. Whole-cell phase contrast imaging at the nanoscale using Fresnel Coherent Diffractive Imaging Tomography

    PubMed Central

    Jones, Michael W. M.; van Riessen, Grant A.; Abbey, Brian; Putkunz, Corey T.; Junker, Mark D.; Balaur, Eugeniu; Vine, David J.; McNulty, Ian; Chen, Bo; Arhatari, Benedicta D.; Frankland, Sarah; Nugent, Keith A.; Tilley, Leann; Peele, Andrew G.

    2013-01-01

    X-ray tomography can provide structural information of whole cells in close to their native state. Radiation-induced damage, however, imposes a practical limit to image resolution, and as such, a choice between damage, image contrast, and image resolution must be made. New coherent diffractive imaging techniques, such Fresnel Coherent Diffractive Imaging (FCDI), allows quantitative phase information with exceptional dose efficiency, high contrast, and nano-scale resolution. Here we present three-dimensional quantitative images of a whole eukaryotic cell by FCDI at a spatial resolution below 70 nm with sufficient phase contrast to distinguish major cellular components. From our data, we estimate that the minimum dose required for a similar resolution is close to that predicted by the Rose criterion, considerably below accepted estimates of the maximum dose a frozen-hydrated cell can tolerate. Based on the dose efficiency, contrast, and resolution achieved, we expect this technique will find immediate applications in tomographic cellular characterisation. PMID:23887204

  20. Coded apertures allow high-energy x-ray phase contrast imaging with laboratory sources

    NASA Astrophysics Data System (ADS)

    Ignatyev, K.; Munro, P. R. T.; Chana, D.; Speller, R. D.; Olivo, A.

    2011-07-01

    This work analyzes the performance of the coded-aperture based x-ray phase contrast imaging approach, showing that it can be used at high x-ray energies with acceptable exposure times. Due to limitations in the used source, we show images acquired at tube voltages of up to 100 kVp, however, no intrinsic reason indicates that the method could not be extended to even higher energies. In particular, we show quantitative agreement between the contrast extracted from the experimental x-ray images and the theoretical one, determined by the behavior of the material's refractive index as a function of energy. This proves that all energies in the used spectrum contribute to the image formation, and also that there are no additional factors affecting image contrast as the x-ray energy is increased. We also discuss the method flexibility by displaying and analyzing the first set of images obtained while varying the relative displacement between coded-aperture sets, which leads to image variations to some extent similar to those observed when changing the crystal angle in analyzer-based imaging. Finally, we discuss the method's possible advantages in terms of simplification of the set-up, scalability, reduced exposure times, and complete achromaticity. We believe this would helpful in applications requiring the imaging of highly absorbing samples, e.g., material science and security inspection, and, in the way of example, we demonstrate a possible application in the latter.

  1. A feasibility study for compressed sensing combined phase contrast MR angiography reconstruction

    NASA Astrophysics Data System (ADS)

    Lee, Dong-Hoon; Hong, Cheol-Pyo; Lee, Man-Woo; Han, Bong-Soo

    2012-02-01

    Phase contrast magnetic resonance angiography (PC MRA) is a technique for flow velocity measurement and vessels visualization, simultaneously. The PC MRA takes long scan time because each flow encoding gradients which are composed bipolar gradient type need to reconstruct the angiography image. Moreover, it takes more image acquisition time when we use the PC MRA at the low-tesla MRI system. In this study, we studied and evaluation of feasibility for CS MRI reconstruction combined PC MRA which data acquired by low-tesla MRI system. We used non-linear reconstruction algorithm which named Bregman iteration for CS image reconstruction and validate the usefulness of CS combined PC MRA reconstruction technique. The results of CS reconstructed PC MRA images provide similar level of image quality between fully sampled reconstruction data and sparse sampled reconstruction using CS technique. Although our results used half of sampling ratio and do not used specification hardware device or performance which are improving the temporal resolution of MR image acquisition such as parallel imaging reconstruction using phased array coil or non-cartesian trajectory, we think that CS combined PC MRA technique will be helpful to increase the temporal resolution and at low-tesla MRI system.

  2. Flow-based segmentation of the large thoracic arteries in tridirectional phase-contrast MRI

    NASA Astrophysics Data System (ADS)

    Schmidt, Michael; Unterhinninghofen, Roland; Ley, Sebastian; Dillmann, Rüdiger

    2009-02-01

    Tridirectional Phase-Contrast (PC)-MRI sequences provide spatially and temporally resolved measurements of blood flow velocity vectors in the human body. Analyzing flow conditions based on these datasets requires prior segmentation of the vessels of interest. In view of decreased quality of morphology images in PC-MRI sequences, the flow data provides valuable information to support reliable segmentation. This work presents a semi-automatic approach for segmenting the large arteries utilizing both morphology and flow information. It consists of two parts, the extraction of a simplified vessel model based on vessel centerlines and diameters, and a following refinement of the resulting surface for each time frame. Vessel centerlines and diameters are extracted using an offset adaptive medialness function that estimates a voxel's likelihood of belonging to a vessel centerline. The resulting centerline model is manually post-processed to select the appropriate centerlines and link possible gaps. The surface described by the final centerline model is used to initialize a 3D level set segmentation of each time frame. Deformation velocities that depend on both morphology and flow information are proposed and a new approach to account for the curved shape of vessels is introduced. The described segmentation system has been successfully applied on a total of 22 datasets of the thoracic aorta and the pulmonary arteries. Resulting segmentations have been assessed by an expert radiologist and were considered to be very satisfactory.

  3. Micro Soft Tissues Visualization Based on X-Ray Phase-Contrast Imaging

    PubMed Central

    Zhang, Lu; Luo, Shuqian

    2011-01-01

    The current imaging methods have a limited ability to visualize microstructures of biological soft tissues. Small lesions cannot be detected at the early stage of the disease. Phase contrast imaging (PCI) is a novel non-invasive imaging technique that can provide high contrast images of soft tissues by the use of X-ray phase shift. It is a new choice in terms of non-invasively revealing soft tissue details. In this study, the lung and hepatic fibrosis models of mice and rats were used to investigate the ability of PCI in microstructures observation of soft tissues. Our results demonstrated that different liver fibrosis stages could be distinguished non-invasively by PCI. The three-dimensional morphology of a segment of blood vessel was constructed. Noteworthy, the blood clot inside the vessel was visualized in three dimensions which provided a precise description of vessel stenosis. Furthermore, the whole lung airways including the alveoli were obtained. We had specifically highlighted its use in the visualization and assessment of the alveoli. To our knowledge, this was the first time for non-invasive alveoli imaging using PCI. This finding may offer a new perspective on the diagnosis of respiratory disease. All the results confirmed that PCI will be a valuable tool in biological soft tissues imaging. PMID:21892370

  4. Potential for Imaging Engineered Tissues with X-Ray Phase Contrast

    PubMed Central

    Appel, Alyssa; Anastasio, Mark A.

    2011-01-01

    As the field of tissue engineering advances, it is crucial to develop imaging methods capable of providing detailed three-dimensional information on tissue structure. X-ray imaging techniques based on phase-contrast (PC) have great potential for a number of biomedical applications due to their ability to provide information about soft tissue structure without exogenous contrast agents. X-ray PC techniques retain the excellent spatial resolution, tissue penetration, and calcified tissue contrast of conventional X-ray techniques while providing drastically improved imaging of soft tissue and biomaterials. This suggests that X-ray PC techniques are very promising for evaluation of engineered tissues. In this review, four different implementations of X-ray PC imaging are described and applications to tissues of relevance to tissue engineering reviewed. In addition, recent applications of X-ray PC to the evaluation of biomaterial scaffolds and engineered tissues are presented and areas for further development and application of these techniques are discussed. Imaging techniques based on X-ray PC have significant potential for improving our ability to image and characterize engineered tissues, and their continued development and optimization could have significant impact on the field of tissue engineering. PMID:21682604

  5. Accessing nonlinear phase contrast in biological tissue using femtosecond laser pulse shaping

    NASA Astrophysics Data System (ADS)

    Fischer, Martin C.; Samineni, Prathyush; Li, Baolei; Claytor, Kevin; Warren, Warren S.

    2011-07-01

    Nonlinear imaging takes advantage of the localized nature of the interaction to achieve high spatial resolution, optical sectioning, and deeper penetration in tissue. However, nonlinear contrast (other than fluorescence or harmonic generation) is generally difficult to measure because it is overwhelmed by the large background of detected illumination light. Especially challenging to measure is the nonlinear refractive index - accessing this quantity would allow the extension of widely employed phase microscopy methods to the nonlinear regime. We have developed a technique to suppress the background in these types of measurements by using femtosecond pulse shaping to encode nonlinear interactions in background-free regions of the frequency spectrum. Using this individual pulse shaping based technique we have been able to measure self-phase modulation (SPM) in highly scattering environments, such as biological tissue, with very modest power levels. Using our measurement technique we have demonstrated strong intrinsic SPM signatures of glutamate-induced neuronal activity in hippocampal brain slices. We have also extended this measurement method to cross-phase modulation, the two-color analogue to SPM. The two-color approach dramatically improves the measurement sensitivity by reducing undesired background and associated noise. We will describe the nonlinear phase contrast measurement technique and report on its application for imaging neuronal activity.

  6. X-ray differential phase-contrast tomographic reconstruction with a phase line integral retrieval filter

    NASA Astrophysics Data System (ADS)

    Fu, Jian; Hu, Xinhua; Li, Chen

    2015-04-01

    We report an alternative reconstruction technique for x-ray differential phase-contrast computed tomography (DPC-CT). This approach is based on a new phase line integral projection retrieval filter, which is rooted in the derivative property of the Fourier transform and counteracts the differential nature of the DPC-CT projections. It first retrieves the phase line integral from the DPC-CT projections. Then the standard filtered back-projection (FBP) algorithms popular in x-ray absorption-contrast CT are directly applied to the retrieved phase line integrals to reconstruct the DPC-CT images. Compared with the conventional DPC-CT reconstruction algorithms, the proposed method removes the Hilbert imaginary filter and allows for the direct use of absorption-contrast FBP algorithms. Consequently, FBP-oriented image processing techniques and reconstruction acceleration softwares that have already been successfully used in absorption-contrast CT can be directly adopted to improve the DPC-CT image quality and speed up the reconstruction.

  7. Low-dose phase contrast tomography with conventional x-ray sources

    SciTech Connect

    Hagen, C. K. Endrizzi, M.; Diemoz, P. C.; Olivo, A.; Munro, P. R. T.

    2014-07-15

    Purpose: The edge illumination (EI) x-ray phase contrast imaging (XPCi) method has been recently further developed to perform tomographic and, thus, volumetric imaging. In this paper, the first tomographic EI XPCi images acquired with a conventional x-ray source at dose levels below that used for preclinical small animal imaging are presented. Methods: Two test objects, a biological sample and a custom-built phantom, were imaged with a laboratory-based EI XPCi setup in tomography mode. Tomographic maps that show the phase shift and attenuating properties of the object were reconstructed, and analyzed in terms of signal-to-noise ratio and quantitative accuracy. Dose measurements using thermoluminescence devices were performed. Results: The obtained images demonstrate that phase based imaging methods can provide superior results compared to attenuation based modalities for weakly attenuating samples also in 3D. Moreover, and, most importantly, they demonstrate the feasibility of low-dose imaging. In addition, the experimental results can be considered quantitative within the constraints imposed by polychromaticity. Conclusions: The results, together with the method's dose efficiency and compatibility with conventional x-ray sources, indicate that tomographic EI XPCi can become an important tool for the routine imaging of biomedical samples.

  8. Phase-contrast zoom tomography reveals precise locations of macrophages in mouse lungs

    PubMed Central

    Krenkel, Martin; Markus, Andrea; Bartels, Matthias; Dullin, Christian; Alves, Frauke; Salditt, Tim

    2015-01-01

    We have performed x-ray phase-contrast tomography on mouse lung tissue. Using a divergent x-ray beam generated by nanoscale focusing, we used zoom tomography to produce three-dimensional reconstructions with selectable magnification, resolution, and field of view. Thus, macroscopic tissue samples extending over several mm can be studied in sub-cellular-level structural detail. The zoom capability and, in particular, the high dose efficiency are enabled by the near-perfect exit wavefront of an optimized x-ray waveguide channel. In combination with suitable phase-retrieval algorithms, challenging radiation-sensitive and low-contrast samples can be reconstructed with minimal artefacts. The dose efficiency of the method is demonstrated by the reconstruction of living macrophages both with and without phagocytized contrast agents. We also used zoom tomography to visualize barium-labelled macrophages in the context of morphological structures in asthmatic and healthy mouse lung tissue one day after intratracheal application. The three-dimensional reconstructions showed that the macrophages predominantly localized to the alveoli, but they were also found in bronchial walls, indicating that these cells might be able to migrate from the lumen of the bronchi through the epithelium. PMID:25966338

  9. Phase retrieval and differential phase-contrast imaging with low-brilliance X-ray sources

    NASA Astrophysics Data System (ADS)

    Pfeiffer, Franz; Weitkamp, Timm; Bunk, Oliver; David, Christian

    2006-04-01

    X-ray radiographic absorption imaging is an invaluable tool in medical diagnostics and materials science. For biological tissue samples, polymers or fibre composites, however, the use of conventional X-ray radiography is limited due to their weak absorption. This is resolved at highly brilliant X-ray synchrotron or micro-focus sources by using phase-sensitive imaging methods to improve the contrast. However, the requirements of the illuminating radiation mean that hard-X-ray phase-sensitive imaging has until now been impractical with more readily available X-ray sources, such as X-ray tubes. In this letter, we report how a setup consisting of three transmission gratings can efficiently yield quantitative differential phase-contrast images with conventional X-ray tubes. In contrast with existing techniques, the method requires no spatial or temporal coherence, is mechanically robust, and can be scaled up to large fields of view. Our method provides all the benefits of contrast-enhanced phase-sensitive imaging, but is also fully compatible with conventional absorption radiography. It is applicable to X-ray medical imaging, industrial non-destructive testing, and to other low-brilliance radiation, such as neutrons or atoms.

  10. High-throughput 3D tracking of bacteria on a standard phase contrast microscope

    PubMed Central

    Taute, K.M.; Gude, S.; Tans, S.J.; Shimizu, T.S.

    2015-01-01

    Bacteria employ diverse motility patterns in traversing complex three-dimensional (3D) natural habitats. 2D microscopy misses crucial features of 3D behaviour, but the applicability of existing 3D tracking techniques is constrained by their performance or ease of use. Here we present a simple, broadly applicable, high-throughput 3D bacterial tracking method for use in standard phase contrast microscopy. Bacteria are localized at micron-scale resolution over a range of 350 × 300 × 200 μm by maximizing image cross-correlations between their observed diffraction patterns and a reference library. We demonstrate the applicability of our technique to a range of bacterial species and exploit its high throughput to expose hidden contributions of bacterial individuality to population-level variability in motile behaviour. The simplicity of this powerful new tool for bacterial motility research renders 3D tracking accessible to a wider community and paves the way for investigations of bacterial motility in complex 3D environments. PMID:26522289

  11. Interior tomography in x-ray differential phase contrast CT imaging

    NASA Astrophysics Data System (ADS)

    Thériault Lauzier, Pascal; Qi, Zhihua; Zambelli, Joseph; Bevins, Nicholas; Chen, Guang-Hong

    2012-05-01

    Differential phase contrast computed tomography (DPC-CT) is an x-ray imaging method that uses the wave properties of imaging photons as the contrast mechanism. It has been demonstrated that DPC images can be obtained using a conventional x-ray tube and a Talbot-Lau-type interferometer. Due to the limited size of the gratings, current data acquisition systems only offer a limited field of view, and thus are prone to data truncation. As a result, the reconstructed DPC-CT image may suffer from image artifacts and increased inaccuracy in the reconstructed image values. In this paper, we demonstrate that a small region of interest (ROI) within a large object can be accurately and stably reconstructed using fully truncated projection datasets provided that a priori information on electron density is known for a small region inside the ROI. The method reconstructs an image iteratively to satisfy a group of physical conditions by using a projection onto convex set (POCS) approach. In this work, this POCS algorithm is validated using both numerical simulations and physical phantom experimental data. In both cases, the root mean square error is reduced by an order of magnitude with respect to the truncated analytic reconstructions. Truncation artifacts observed in the latter reconstructions are eliminated using the POCS algorithm.

  12. Evaluation of microbubble contrast agents for dynamic imaging with x-ray phase contrast

    PubMed Central

    Millard, T. P.; Endrizzi, M.; Everdell, N.; Rigon, L.; Arfelli, F.; Menk, R. H.; Stride, E.; Olivo, A.

    2015-01-01

    X-rays are commonly used as a means to image the inside of objects opaque to visible light, as their short wavelength allows penetration through matter and the formation of high spatial resolution images. This physical effect has found particular importance in medicine where x-ray based imaging is routinely used as a diagnostic tool. Increasingly, however, imaging modalities that provide functional as well as morphological information are required. In this study the potential to use x-ray phase based imaging as a functional modality through the use of microbubbles that can be targeted to specific biological processes is explored. We show that the concentration of a microbubble suspension can be monitored quantitatively whilst in flow using x-ray phase contrast imaging. This could provide the basis for a dynamic imaging technique that combines the tissue penetration, spatial resolution, and high contrast of x-ray phase based imaging with the functional information offered by targeted imaging modalities. PMID:26219661

  13. Correction of data truncation artifacts in differential phase contrast (DPC) tomosynthesis imaging.

    PubMed

    Garrett, John; Ge, Yongshuai; Li, Ke; Chen, Guang-Hong

    2015-10-01

    The use of grating based Talbot-Lau interferometry permits the acquisition of differential phase contrast (DPC) imaging with a conventional medical x-ray source and detector. However, due to the limited area of the gratings, limited area of the detector, or both, data truncation image artifacts are often observed in tomographic DPC acquisitions and reconstructions, such as tomosynthesis (limited-angle tomography). When data are truncated in the conventional x-ray absorption tomosynthesis imaging, a variety of methods have been developed to mitigate the truncation artifacts. However, the same strategies used to mitigate absorption truncation artifacts do not yield satisfactory reconstruction results in DPC tomosynthesis reconstruction. In this work,several new methods have been proposed to mitigate data truncation artifacts in a DPC tomosynthesis system. The proposed methods have been validated using experimental data of a mammography accreditation phantom, a bovine udder, as well as several human cadaver breast specimens using a bench-top DPC imaging system at our facility. PMID:26394181

  14. Self-Navigation with Compressed Sensing for 2D Translational Motion Correction in Free-Breathing Coronary MRI: A Feasibility Study

    PubMed Central

    Bonanno, Gabriele; Puy, Gilles; Wiaux, Yves; van Heeswijk, Ruud B.; Piccini, Davide; Stuber, Matthias

    2014-01-01

    conclusion, compressed sensing may become a critical adjunct for 2D translational motion correction in free-breathing cardiac imaging with high spatial resolution. An expansion to modern 3D approaches is now warranted. PMID:25171369

  15. Quantitative studies on inner interfaces in conical metal joints using hard x-ray inline phase contrast radiography

    NASA Astrophysics Data System (ADS)

    Zabler, S.; Rack, T.; Rack, A.; Nelson, K.

    2010-10-01

    Quantitative investigation of micrometer and submicrometer gaps between joining metal surfaces is applied to conical plug-socket connections in dental titanium implants. Microgaps of widths well beyond the resolving power of industrial x-ray systems are imaged by synchrotron phase contrast radiography. Furthermore, by using an analytical model for the relatively simple sample geometry and applying it to numerical forward simulations of the optical Fresnel propagation, we show that quantitative measurements of the microgap width down to 0.1 μm are possible. Image data recorded at the BAMline (BESSY-II light source, Germany) are presented, with the resolving power of the imaging system being 4 μm in absorption mode and ˜14 μm in phase contrast mode (z2=0.74 m). Thus, phase contrast radiography, combined with numerical forward simulations, is capable of measuring the widths of gaps that are two orders of magnitude thinner than the conventional detection limit.

  16. Nondestructive volumetric imaging of tissue microstructure with benchtop x-ray phase-contrast tomography and critical point drying

    PubMed Central

    Zysk, Adam M.; Garson, Alfred B.; Xu, Qiaofeng; Brey, Eric M.; Zhou, Wei; Brankov, Jovan G.; Wernick, Miles N.; Kuszak, Jerome R.; Anastasio, Mark A.

    2012-01-01

    The in vitro investigation of many optically opaque biological microstructures requires 3D analysis at high resolution over a large field of view. We demonstrate a new nondestructive volumetric imaging technique that eliminates the structural and computational limitations of conventional 2D optical microscopy by combining x-ray phase-contrast tomography with critical point drying sample preparation. We experimentally demonstrate the enhancement of small features afforded by phase-contrast imaging and show the contrast improvement afforded by the drying of a hydrated specimen. We further demonstrate the biological application of this technique by imaging the microstructure of the accommodative apparatus in a primate eye using a benchtop phase-contrast tomography system. PMID:22876355

  17. Differential Phase-Contrast Scanning X-Ray Microscope For Observation Of Low-Z element Specimen

    SciTech Connect

    Takeuchi, Akihisa; Uesugi, Kentaro; Suzuki, Yoshio

    2010-07-23

    Differential phase-contrast scanning x-ray microscope/microtomography have been developed. A fast readout charge-coupled device (CCD) camera coupled with a visible-light conversion unit is used as a detector to record the transmitted intensity distribution of far-field image for every pixel in a scan. Simultaneous absorption and phase-contrast images are given from a single scan by image-processing of the CCD frames. The system is constructed at BL20XU of SPring-8, and its feasibility is demonstrated at the photon energy of 8 keV. A tantalum test chart is observed and its finest structure of 140 nm pitch pattern is clearly observed. Measured phase sensitivity is approximately {lambda}/270. Some low-Z element specimens are observed and obtained phase contrast image shows much higher sensitivity than that of absorption contrast.

  18. Optimization of in-line phase contrast particle image velocimetry using a laboratory x-ray source

    SciTech Connect

    Ng, I.; Fouras, A.; Paganin, D. M.

    2012-10-01

    Phase contrast particle image velocimetry (PIV) using a laboratory x-ray microfocus source is investigated using a numerical model. Phase contrast images of 75 {mu}m air bubbles, embedded within water exhibiting steady-state vortical flow, are generated under the paraxial approximation using a tungsten x-ray spectrum at 30 kVp. Propagation-based x-ray phase-contrast speckle images at a range of source-object and object-detector distances are generated, and used as input into a simulated PIV measurement. The effects of source-size-induced penumbral blurring, together with the finite dynamic range of the detector, are accounted for in the simulation. The PIV measurement procedure involves using the cross-correlation between temporally sequential speckle images to estimate the transverse displacement field for the fluid. The global error in the PIV reconstruction, for the set of simulations that was performed, suggests that geometric magnification is the key parameter for designing a laboratory-based x-ray phase-contrast PIV system. For the modeled system, x-ray phase-contrast PIV data measurement can be optimized to obtain low error (<0.2 effective pixel of the detector) in the system with magnification lying in the range between 1.5 and 3. For large effective pixel size (>15 {mu}m) of the detector, high geometric magnification (>2.5) is desired, while for large source size system (FWHM > 30 {mu}m), low magnification (<1.5) would be suggested instead. The methods developed in this paper can be applied to optimizing phase-contrast velocimetry using a variety of laboratory x-ray sources.

  19. Noninvasive Assessment of Transstenotic Pressure Gradients in Porcine Renal Artery Stenoses by Using Vastly Undersampled Phase-Contrast MR Angiography

    PubMed Central

    Bley, Thorsten A.; Johnson, Kevin M.; François, Christopher J.; Reeder, Scott B.; Schiebler, Mark L.; R. Landgraf, Benjamin; Consigny, Daniel; Grist, Thomas M.

    2011-01-01

    Purpose: To compare noninvasive transstenotic pressure gradient (TSPG) measurements derived from high-spatial- and temporal-resolution four-dimensional magnetic resonance (MR) flow measurements with invasive measurements obtained from endovascular pressure wires with digital subtraction angiographic guidance. Materials and Methods: After Animal Care and Use Committee approval, bilateral renal artery stenosis (RAS) was created surgically in 12 swine. Respiratory-gated phase-contrast vastly undersampled isotropic projection (VIPR) MR angiography of the renal arteries was performed with a 1.5-T clinical MR system (repetition time, 11.4 msec; echo time [first echo], 3.7 msec; 18 000 projection angles; imaging volume, 260 × 260 × 200 mm; acquired isotropic spatial resolution, 1.0 × 1.0 × 1.0 mm; velocity encoding, 150 cm/sec). Velocities measured with phase-contrast VIPR were used to calculate TSPGs by using Navier-Stokes equations. These were compared with endovascular pressure measurements (mean and peak) performed by using fluoroscopic guidance with regression analysis. Results: In 19 renal arteries with an average stenosis of 62% (range, 0%–87%), there was excellent correlation between the noninvasive TSPG measurement with phase-contrast VIPR and invasive TSPG measurement for mean TSPG (R2 = 95.4%) and strong correlation between noninvasive TSPG and invasive TSPG for the peak TSPG measures (R2 = 82.6%). The phase-contrast VIPR–derived TSPG measures were slightly lower than the endovascular measurements. In four arteries with severe stenoses and one occlusion (mean, 86%; range, 75%–100%), the residual lumen within the stenosis was too small to determine TSPG with phase-contrast VIPR. Conclusion: The unenhanced MR angiographic technique with phase-contrast VIPR allows for accurate noninvasive assessment of hemodynamic significance in a porcine model of RAS with highly accurate TSPG measurements. © RSNA, 2011 Supplemental material: http

  20. Feasibility testing of a pre-clinical coded aperture phase contrast imaging configuration using a simple fast Monte Carlo simulator

    PubMed Central

    Kavanagh, Anthony; Olivo, Alessandro; Speller, Robert; Vojnovic, Borivoj

    2013-01-01

    A simple method of simulating possible coded aperture phase contrast X-ray imaging apparatus is presented. The method is based on ray tracing, with the rays treated ballistically within a voxelized sample and with the phase-shift-induced angular deviations and absorptions applied at a plane in the middle of the sample. For the particular case of a coded aperture phase contrast configuration suitable for small animal pre-clinical imaging we present results obtained using a high resolution voxel array representation of a mathematically-defined ‘digital’ mouse. At the end of the article a link to the software is supplied. PMID:24466479

  1. Glancing angle Talbot-Lau grating interferometers for phase contrast imaging at high x-ray energy

    NASA Astrophysics Data System (ADS)

    Stutman, D.; Finkenthal, M.

    2012-08-01

    A Talbot-Lau interferometer is demonstrated using micro-periodic gratings inclined at a glancing angle along the light propagation direction. Due to the increase in the effective thickness of the absorption gratings, the device enables differential phase contrast imaging at high x-ray energy, with improved fringe visibility (contrast). For instance, at 28° glancing angle, we obtain up to ˜35% overall interferometer contrast with a spectrum having ˜43 keV mean energy, suitable for medical applications. In addition, glancing angle interferometers could provide high contrast at energies above 100 keV, enabling industrial and security applications of phase contrast imaging.

  2. Milestones and basic principles of grating-based x-ray and neutron phase-contrast imaging

    SciTech Connect

    Pfeiffer, Franz

    2012-07-31

    This is a review of the most important milestones in the last ten years of development in the field of grating-based x-ray and neutron imaging. It provides a description of the basic imaging principles of grating-based phase-contrast and dark-field radiography and present some exemplary multimodal radiography results obtained with x-rays and neutrons. Furthermore, it reviews the theory of grating-based quantitative transmission, phase-contrast, and dark-field scattering computed tomography.

  3. Quantitative evaluation of single-shot inline phase contrast imaging using an inverse compton x-ray source

    SciTech Connect

    Oliva, P.; Carpinelli, M.; Golosio, B.; Delogu, P.; Endrizzi, M.; Park, J.; Pogorelsky, I.; Yakimenko, V.; Williams, O.; Rosenzweig, J.

    2010-09-27

    Inverse compton scattering (ICS) x-ray sources are of current interest in biomedical imaging. We present an experimental demonstration of inline phase contrast imaging using a single picosecond pulse of the ICS source located at the BNL Accelerator Test Facility. The phase contrast effect is clearly observed. Its qualities are shown to be in agreement with the predictions of theoretical models through comparison of experimental and simulated images of a set of plastic wires of differing composition and size. Finally, we display an application of the technique to a biological sample, confirming the possibility of time-resolved imaging on the picosecond scale.

  4. Abdominal Aortic Aneurysm (AAA)

    MedlinePlus

    ... Resources Professions Site Index A-Z Abdominal Aortic Aneurysm (AAA) Abdominal aortic aneurysm (AAA) occurs when atherosclerosis ... aortic aneurysm treated? What is an abdominal aortic aneurysm? The aorta, the largest artery in the body, ...

  5. Abdominal CT scan

    MedlinePlus

    ... results may also be due to: Abdominal aortic aneurysm Abscesses Appendicitis Bowel wall thickening Retroperitoneal fibrosis Renal ... Livingstone; 2014:chap 4. Read More Abdominal aortic aneurysm Abdominal aortic aneurysm repair - open Abscess Acute cholecystitis ...

  6. X-ray phase contrast imaging of the breast: Analysis of tissue simulating materials

    SciTech Connect

    Vedantham, Srinivasan; Karellas, Andrew

    2013-04-15

    Purpose: Phase contrast imaging, particularly of the breast, is being actively investigated. The purpose of this work is to investigate the x-ray phase contrast properties of breast tissues and commonly used breast tissue substitutes or phantom materials with an aim of determining the phantom materials best representative of breast tissues. Methods: Elemental compositions of breast tissues including adipose, fibroglandular, and skin were used to determine the refractive index, n= 1 -{delta}+i {beta}. The real part of the refractive index, specifically the refractive index decrement ({delta}), over the energy range of 5-50 keV were determined using XOP software (version 2.3, European Synchrotron Radiation Facility, France). Calcium oxalate and calcium hydroxyapatite were considered to represent the material compositions of microcalcifications in vivo. Nineteen tissue substitutes were considered as possible candidates to represent adipose tissue, fibroglandular tissue and skin, and four phantom materials were considered as possible candidates to represent microcalcifications. For each material, either the molecular formula, if available, or the elemental composition based on weight fraction, was used to determine {delta}. At each x-ray photon energy, the absolute percent difference in {delta} between the breast tissue and the substitute material was determined, from which three candidates were selected. From these candidate tissue substitutes, the material that minimized the absolute percent difference in linear attenuation coefficient {mu}, and hence {beta}, was considered to be best representative of that breast tissue. Results: Over the energy range of 5-50 keV, while the {delta} of CB3 and fibroglandular tissue-equivalent material were within 1% of that of fibroglandular tissue, the {mu} of fibroglandular tissue-equivalent material better approximated the fibroglandular tissue. While the {delta} of BR10 and adipose tissue-equivalent material were within 1% of

  7. Anatomical background noise power spectrum in differential phase contrast breast images

    NASA Astrophysics Data System (ADS)

    Garrett, John; Ge, Yongshuai; Li, Ke; Chen, Guang-Hong

    2015-03-01

    In x-ray breast imaging, the anatomical noise background of the breast has a significant impact on the detection of lesions and other features of interest. This anatomical noise is typically characterized by a parameter, β, which describes a power law dependence of anatomical noise on spatial frequency (the shape of the anatomical noise power spectrum). Large values of β have been shown to reduce human detection performance, and in conventional mammography typical values of β are around 3.2. Recently, x-ray differential phase contrast (DPC) and the associated dark field imaging methods have received considerable attention as possible supplements to absorption imaging for breast cancer diagnosis. However, the impact of these additional contrast mechanisms on lesion detection is not yet well understood. In order to better understand the utility of these new methods, we measured the β indices for absorption, DPC, and dark field images in 15 cadaver breast specimens using a benchtop DPC imaging system. We found that the measured β value for absorption was consistent with the literature for mammographic acquisitions (β = 3.61±0.49), but that both DPC and dark field images had much lower values of β (β = 2.54±0.75 for DPC and β = 1.44±0.49 for dark field). In addition, visual inspection showed greatly reduced anatomical background in both DPC and dark field images. These promising results suggest that DPC and dark field imaging may help provide improved lesion detection in breast imaging, particularly for those patients with dense breasts, in whom anatomical noise is a major limiting factor in identifying malignancies.

  8. Error Analysis of Cine Phase Contrast MRI Velocity Measurements used for Strain Calculation

    PubMed Central

    Jensen, Elisabeth R.; Morrow, Duane A.; Felmlee, Joel P.; Odegard, Gregory M.; Kaufman, Kenton R.

    2014-01-01

    Cine Phase Contrast (CPC) MRI offers unique insight into localized skeletal muscle behavior by providing the ability to quantify muscle strain distribution during cyclic motion. Muscle strain is obtained by temporally integrating and spatially differentiating CPC-encoded velocity. The aim of this study was to quantify measurement accuracy and precision and to describe error propagation into displacement and strain. Using an MRI-compatible jig to move a B-gel phantom within a 1.5T MRI bore, CPC-encoded velocities were collected. The three orthogonal encoding gradients (through plane, frequency, and phase) were evaluated independently in post-processing. Two systematic error types were corrected: eddy current-induced bias and calibration-type error. Measurement accuracy and precision were quantified before and after removal of systematic error. Through plane- and frequency-encoded data accuracy were within 0.4mm/s after removal of systematic error – a 70% improvement over the raw data. Corrected phase-encoded data accuracy was within 1.3mm/s. Measured random error was between 1 to 1.4mm/s, which followed the theoretical prediction. Propagation of random measurement error into displacement and strain was found to depend on the number of tracked time segments, time segment duration, mesh size, and dimensional order. To verify this, theoretical predictions were compared to experimentally calculated displacement and strain error. For the parameters tested, experimental and theoretical results aligned well. Random strain error approximately halved with a two-fold mesh size increase, as predicted. Displacement and strain accuracy were within 2.6mm and 3.3%, respectively. These results can be used to predict the accuracy and precision of displacement and strain in user-specific applications. PMID:25433567

  9. Talbot phase-contrast x-ray imaging for the small joints of the hand

    NASA Astrophysics Data System (ADS)

    Stutman, Dan; Beck, Thomas J.; Carrino, John A.; Bingham, Clifton O.

    2011-09-01

    A high-resolution radiographic method for soft tissues in the small joints of the hand would aid in the study and treatment of rheumatoid arthritis (RA) and osteoarthritis (OA), which often attacks these joints. Of particular interest would be imaging with <100 µm resolution the joint cartilage, whose integrity is a main indicator of disease. Differential phase-contrast (DPC) or refraction-based x-ray imaging with Talbot grating interferometers could provide such a method, since it enhances soft tissue contrast and can be implemented with conventional x-ray tubes. A numerical joint phantom was first developed to assess the angular sensitivity and spectrum needed for a hand DPC system. The model predicts that, due to quite similar refraction indexes for joint soft tissues, the refraction effects are very small, requiring high angular resolution. To compare our model to experiment we built a high-resolution bench-top interferometer using 10 µm period gratings, a W anode tube and a CCD-based detector. Imaging experiments on animal cartilage and on a human finger support the model predictions. For instance, the estimated difference between the index of refraction of cartilage and water is of only several percent at ~25 keV mean energy, comparable to that between the linear attenuation coefficients. The potential advantage of DPC imaging thus comes mainly from the edge enhancement at the soft tissue interfaces. Experiments using a cadaveric human finger are also qualitatively consistent with the joint model, showing that refraction contrast is dominated by tendon embedded in muscle, with the cartilage layer difficult to observe in our conditions. Nevertheless, the model predicts that a DPC radiographic system for the small hand joints of the hand could be feasible using a low energy quasi-monochromatic source, such as a K-edge filtered Rh or Mo tube, in conjunction with a ~2 m long 'symmetric' interferometer operated in a high Talbot order.

  10. Investigating biofilm structure using x-ray microtomography and gratings-based phase contrast

    SciTech Connect

    Miller, Erin A.; Xiao, Xianghui; Miller, Micah D.; Keller, Paul E.; White, Timothy A.; Marshall, Matthew J.

    2012-10-17

    Direct examination of natural and engineered environments has revealed that the majority of microorganisms in these systems live in structured communities termed biofilms. To gain a better understanding for how biofilms function and interact with their local environment, fundamental capabilities for enhanced visualization, compositional analysis, and functional characterization of biofilms are needed. For pore-scale and community-scale analysis (100’s of nm to 10’s of microns), a variety of surface tools are available. However, understanding biofilm structure in complex three-dimensional (3-D) environments is considerably more difficult. X-ray microtomography can reveal a biofilm’s internal structure, but the obtaining sufficient contrast to image low-Z biological material against a higher-Z substrate makes detecting biofilms difficult. Here we present results imaging Shewanella oneidensis biofilms on a Hollow-fiber Membrane Biofilm Reactor (HfMBR), using the x-ray microtomography system at sector 2-BM of the Advanced Photon Source (APS), at energies ranging from 13-15.4 keV and pixel sizes of 0.7 and 1.3 μm/pixel. We examine the use of osmium (Os) as a contrast agent to enhance biofilm visibility and demonstrate that staining improves imaging of hydrated biofilms. We also present results using a Talbot interferometer to provide phase and scatter contrast information in addition to absorption. Talbot interferometry allows imaging of unstained hydrated biofilms with phase contrast, while absorption contrast primarily highlights edges and scatter contrast provides little information. However, the gratings used here limit the spatial resolution to no finer than 2 μm, which hinders the ability to detect small features. Future studies at higher resolution or higher Talbot order for greater sensitivity to density variations may improve imaging.

  11. Direct Comparison of Gyrokinetic Turbulence Simulations with Phase Contrast Imaging Fluctuation Measurements

    NASA Astrophysics Data System (ADS)

    Ernst, Darin; Long, A.; Basse, N.; Lin, L.; Porkolab, M.; Dorland, W.

    2006-04-01

    We have developed a synthetic diagnostic^1 for the GS2 gyrokinetic code for direct comparisons with phase contrast imaging (PCI) measurements of density fluctuations in Alcator C-Mod. The gyrokinetic simulation is carried out in a local, field line following flux-tube, while PCI measures density fluctuations along 32 chords passing vertically through the plasma cross-section.^2 Transforming from Clebsch to cartesian coordinates, and integrating appropriately over portions of the flux tube viewed by the diagnostic, yields a density fluctuation spectrum versus wavenumber kR in the major radius direction. To achieve vertical localization, we examine an ITB case in which the spectrum is dominated by a strong trapped electron mode, localized near the half-radius. The wavelength spectrum from the simulations, using the synthetic diagnostic, closely reproduces the PCI spectrum. Contributions from kψ, where B=∇αx∇ψ, downshift the GS2 kα spectrum to improve upon our previous raw comparison with the PCI kR spectrum.^3 ^1A. Long, D. R. Ernst et al., Bull. Am. Phys. Soc. 50(8) p. 153, GP1.48, also p. 235, LP1.37 http://www.psfc.mit.edu/research/alcator/pubs/APS/APS2005/ernst.pdf. ^2N. P. Basse et al., Phys. Plasmas 12, 052512 (2005). ^3D. R. Ernst et al., 2004 IAEA Fusion Energy Conference, IAEA-CN116/TH/4-1 http://www-naweb.iaea.org/napc/physics/fec/fec2004/datasets/TH4-1.html, see also Phys. Plasmas 11 (2004) 2637.

  12. Low-dose, phase-contrast mammography with high signal-to-noise ratio

    PubMed Central

    Gromann, Lukas B.; Bequé, Dirk; Scherer, Kai; Willer, Konstantin; Birnbacher, Lorenz; Willner, Marian; Herzen, Julia; Grandl, Susanne; Hellerhoff, Karin; Sperl, Jonathan I.; Pfeiffer, Franz; Cozzini, Cristina

    2016-01-01

    Differential phase-contrast X-ray imaging using a Talbot-Lau interferometer has recently shown promising results for applications in medical imaging. However, reducing the applied radiation dose remains a major challenge. In this study, we consider the realization of a Talbot-Lau interferometer in a high Talbot order to increase the signal-to-noise ratio for low-dose applications. The quantitative performance of π and π/2 systems at high Talbot orders is analyzed through simulations, and the design energy and X-ray spectrum are optimized for mammography. It is found that operation even at very high Talbot orders is feasible and beneficial for image quality. As long as the X-ray spectrum is matched to the visibility spectrum, the SNR continuously increases with the Talbot order for π-systems. We find that the optimal X-ray spectra and design energies are almost independent of the Talbot order and that the overall imaging performance is robust against small variations in these parameters. Discontinuous spectra, such as that from molybdenum, are less robust because the characteristic lines may coincide with minima in the visibility spectra; however, they may offer slightly better performance. We verify this hypothesis by realizing a prototype system with a mean fringe visibility of above 40% at the seventh Talbot order. With this prototype, a proof-of-principle measurement of a freshly dissected breast at reasonable compression to 4 cm is conducted with a mean glandular dose of only 3 mGy but with a high SNR. PMID:26977347

  13. Investigating biofilm structure using x-ray microtomography and gratings-based phase contrast

    NASA Astrophysics Data System (ADS)

    Miller, Erin A.; Xiao, Xianghui; Miller, Micah; Keller, Paul; White, Timothy A.; Marshall, Matthew

    2012-10-01

    Direct examination of natural and engineered environments has revealed that the majority of microorganisms in these systems live in structured communities termed biofilms. To gain a better understanding for how biofilms function and interact with their local environment, fundamental capabilities for enhanced visualization, compositional analysis, and functional characterization of biofilms are needed. For pore-scale and community-scale analysis (100's of nm to 10's of microns), a variety of surface tools are available. However, understanding biofilm structure in complex three-dimensional (3-D) environments is considerably more difficult. X-ray microtomography can reveal a biofilm's internal structure, but obtaining sufficient contrast to image low atomic number (Z) biological material against a higher-Z substrate makes detecting biofilms difficult. Here we present results imaging Shewanella oneidensis biofilms on a Hollow-fiber Membrane Biofilm Reactor (HfMBR), using the x-ray microtomography system at sector 2-BM of the Advanced Photon Source (APS), at energies ranging from 12.9-15.4 keV and pixel sizes of 0.7 and 1.3 μm/pixel. We examine the use of osmium (Os) as a contrast agent to enhance biofilm visibility and demonstrate that staining improves imaging of hydrated biofilms. We also present results using a Talbot interferometer to provide phase and scatter contrast information in addition to absorption. Talbot interferometry allows imaging of unstained hydrated biofilms with phase contrast, while absorption contrast primarily highlights edges and scatter contrast provides little information. However, the gratings used here limit the spatial resolution to no finer than 2 μm, which hinders the ability to detect small features. Future studies at higher resolution or higher Talbot order for greater sensitivity to density variations may improve imaging.

  14. Quantitative Assessment of Murine Articular Cartilage and Bone Using X-Ray Phase-Contrast Imaging

    PubMed Central

    Li, Jun; Yuan, Huihui; Wu, Mingshu; Dong, Linan; Zhang, Lu; Shi, Hongli; Luo, Shuqian

    2014-01-01

    Murine models for rheumatoid arthritis (RA) research can provide important insights for understanding RA pathogenesis and evaluating the efficacy of novel treatments. However, simultaneously imaging both murine articular cartilage and subchondral bone using conventional techniques is challenging because of low spatial resolution and poor soft tissue contrast. X-ray phase-contrast imaging (XPCI) is a new technique that offers high spatial resolution for the visualisation of cartilage and skeletal tissues. The purpose of this study was to utilise XPCI to observe articular cartilage and subchondral bone in a collagen-induced arthritis (CIA) murine model and quantitatively assess changes in the joint microstructure. XPCI was performed on the two treatment groups (the control group and CIA group, n = 9 per group) to monitor the progression of damage to the femur from the knee joint in a longitudinal study (at 0, 4 and 8 weeks after primary injection). For quantitative assessment, morphologic parameters were measured in three-dimensional (3D) images using appropriate image analysis software. Our results showed that the average femoral cartilage volume, surface area and thickness were significantly decreased (P<0.05) in the CIA group compared to the control group. Meanwhile, these decreases were accompanied by obvious destruction of the surface of subchondral bone and a loss of trabecular bone in the CIA group. This study confirms that XPCI technology has the ability to qualitatively and quantitatively evaluate microstructural changes in mouse joints. This technique has the potential to become a routine analysis method for accurately monitoring joint damage and comprehensively assessing treatment efficacy. PMID:25369528

  15. Effects of two different anesthetic protocols on cardiac flow measured by two dimensional phase contrast MRI

    PubMed Central

    Drees, Randi; Johnson, Rebecca A; Stepien, Rebecca L; Del Rio, Alejandro Munoz; François, Christopher J

    2014-01-01

    Companion animals are anesthetized or heavily sedated to comply for cardiac MRI and different anesthetic protocols are expected to have variable effects on functional parameters measured. This study compared two anesthetic protocols (Protocol A: Midazolam, fentanyl; Protocol B: Dexmedetomidine) for their effect on quantitative and qualitative analysis of blood flow through the aortic, pulmonic, mitral and tricuspid valves using 2D phase contrast (PC) MRI in dogs. Mean flow per heartbeat through the pulmonary artery (Qp) and aorta (Qs) was compared to right (RVSV) and left (LVSV) ventricular stroke volumes determined using 2D Cine balanced steady-state free precession MRI as a reference standard. Pulmonary to systemic flow ratio (Qp/Qs) was also calculated. Differences in flow and Qp/Qs values generated using 2D PC MRI were not different between the two anesthetic protocols (P=1). Mean differences between Qp and right ventricular stroke volume (RVSV) were 3.82 (95% limits of agreement: 3.62, −11.26) ml/beat and 1.9 (−7.86, 11.66) ml/beat for anesthesia protocols A and B, respectively. Mean differences between Qs and left ventricular stroke volume (LVSV) were 1.65 (−5.04, 8.34) ml/beat and 0.03 (−4.65, 4.72) ml/beat for anesthesia protocols A and B, respectively. Mild tricuspid or mitral reflux was seen in 2/10 dogs using 2D PC MRI. No aortic or pulmonic insufficiency was observed. This study provides baseline data for evaluation of cardiac blood flow using 2D PC MRI in dogs. Where as no significant difference of cardiac blood flow was found for the anesthetic protocols used, verification in clinically affected patients is desirable. PMID:25124271

  16. X-Ray Phase-Contrast Tomography of Renal Ischemia-Reperfusion Damage

    PubMed Central

    Velroyen, Astrid; Bech, Martin; Zanette, Irene; Schwarz, Jolanda; Rack, Alexander; Tympner, Christiane; Herrler, Tanja; Staab-Weijnitz, Claudia; Braunagel, Margarita; Reiser, Maximilian; Bamberg, Fabian; Pfeiffer, Franz; Notohamiprodjo, Mike

    2014-01-01

    Purpose The aim of the study was to investigate microstructural changes occurring in unilateral renal ischemia-reperfusion injury in a murine animal model using synchrotron radiation. Material and Methods The effects of renal ischemia-reperfusion were investigated in a murine animal model of unilateral ischemia. Kidney samples were harvested on day 18. Grating-Based Phase-Contrast Imaging (GB-PCI) of the paraffin-embedded kidney samples was performed at a Synchrotron Radiation Facility (beam energy of 19 keV). To obtain phase information, a two-grating Talbot interferometer was used applying the phase stepping technique. The imaging system provided an effective pixel size of 7.5 µm. The resulting attenuation and differential phase projections were tomographically reconstructed using filtered back-projection. Semi-automated segmentation and volumetry and correlation to histopathology were performed. Results GB-PCI provided good discrimination of the cortex, outer and inner medulla in non-ischemic control kidneys. Post-ischemic kidneys showed a reduced compartmental differentiation, particularly of the outer stripe of the outer medulla, which could not be differentiated from the inner stripe. Compared to the contralateral kidney, after ischemia a volume loss was detected, while the inner medulla mainly retained its volume (ratio 0.94). Post-ischemic kidneys exhibited severe tissue damage as evidenced by tubular atrophy and dilatation, moderate inflammatory infiltration, loss of brush borders and tubular protein cylinders. Conclusion In conclusion GB-PCI with synchrotron radiation allows for non-destructive microstructural assessment of parenchymal kidney disease and vessel architecture. If translation to lab-based approaches generates sufficient density resolution, and with a time-optimized image analysis protocol, GB-PCI may ultimately serve as a non-invasive, non-enhanced alternative for imaging of pathological changes of the kidney. PMID:25299243

  17. Low-dose, phase-contrast mammography with high signal-to-noise ratio.

    PubMed

    Gromann, Lukas B; Bequé, Dirk; Scherer, Kai; Willer, Konstantin; Birnbacher, Lorenz; Willner, Marian; Herzen, Julia; Grandl, Susanne; Hellerhoff, Karin; Sperl, Jonathan I; Pfeiffer, Franz; Cozzini, Cristina

    2016-02-01

    Differential phase-contrast X-ray imaging using a Talbot-Lau interferometer has recently shown promising results for applications in medical imaging. However, reducing the applied radiation dose remains a major challenge. In this study, we consider the realization of a Talbot-Lau interferometer in a high Talbot order to increase the signal-to-noise ratio for low-dose applications. The quantitative performance of π and π/2 systems at high Talbot orders is analyzed through simulations, and the design energy and X-ray spectrum are optimized for mammography. It is found that operation even at very high Talbot orders is feasible and beneficial for image quality. As long as the X-ray spectrum is matched to the visibility spectrum, the SNR continuously increases with the Talbot order for π-systems. We find that the optimal X-ray spectra and design energies are almost independent of the Talbot order and that the overall imaging performance is robust against small variations in these parameters. Discontinuous spectra, such as that from molybdenum, are less robust because the characteristic lines may coincide with minima in the visibility spectra; however, they may offer slightly better performance. We verify this hypothesis by realizing a prototype system with a mean fringe visibility of above 40% at the seventh Talbot order. With this prototype, a proof-of-principle measurement of a freshly dissected breast at reasonable compression to 4 cm is conducted with a mean glandular dose of only 3 mGy but with a high SNR. PMID:26977347

  18. Renal stones on portal venous phase contrast-enhanced CT: does intravenous contrast interfere with detection?

    PubMed Central

    Dym, R. Joshua; Duncan, Dameon R.; Spektor, Michael; Cohen, Hillel W.; Scheinfeld, Meir H.

    2015-01-01

    Purpose To determine the sensitivity of portal venous phase contrast-enhanced CT for the detection of renal stones. Methods This retrospective study included 97 CT examinations of the abdomen without and with intravenous contrast, including 85 (87.6%) examinations with at least one renal stone on the “gold standard” noncontrast images, as scored by a single radiologist. Three other radiologists each independently reviewed only the contrast-enhanced images from all 97 examinations and recorded all renal stones. Reviewer sensitivity for stones was categorized by stone diameter. Reviewer sensitivity and specificity for stone disease were also calculated on a per-kidney basis. Results The 97 cases included a total of 238 stones ≥1 mm, with a mean (±SD) of 1.2 ± 1.9 stones per kidney and a stone diameter of 3.5 ± 3.0 mm. Pooling data for the three reviewers, sensitivity for all stones was 81%; sensitivity for stones ≥2, ≥3, ≥4, and ≥5 mm was 88%, 95%, 99%, and 98%, respectively. Sensitivity for stone disease on a per-kidney basis was 94% when considering all stones; when considering only stones ≥2, ≥3, and ≥4 mm, sensitivity was 96%, 99%, and 100%, respectively. Specificity for stone disease on a per-kidney basis was 98% overall, 99% when considering only stones ≥2 mm, and 100% when considering only stones ≥3 mm. Conclusion: Contrast-enhanced CT is highly sensitive for the detection of renal stones ≥3 mm in diameter and less sensitive for smaller stones. In cases where the clinical diagnosis is uncertain and performance of a CT examination is being contemplated, intravenous contrast utilization would allow assessment for stone disease while also optimizing evaluation for other conditions. PMID:24504541

  19. Three-dimensional imaging of nerve tissue by x-ray phase-contrast microtomography.

    PubMed Central

    Beckmann, F; Heise, K; Kölsch, B; Bonse, U; Rajewsky, M F; Bartscher, M; Biermann, T

    1999-01-01

    We show that promising information about the three-dimensional (3D) structure of a peripheral nerve can be obtained by x-ray phase-contrast microtomography (p-microCT; Beckmann, F., U. Bonse, F. Busch, and O. Günnewig, 1997. J. Comp. Assist. Tomogr. 21:539-553). P-microCT measures electronic charge density, which for most substances is proportional to mass density in fairly good approximation. The true point-by-point variation of density is thus determined in 3D at presently 1 mg/cm3 standard error (SE). The intracranial part of the rat trigeminal nerve analyzed for the presence of early schwannoma "microtumors" displayed a detailed density structure on p-microCT density maps. The average density of brain and nerve tissue was measured to range from 0.990 to 0.994 g/cm3 and from 1.020 to 1.035 g/cm3, respectively. The brain-nerve interface was well delineated. Within the nerve tissue, a pattern of nerve fibers could be seen that followed the nerve axis and contrasted against the bulk by 7 to 10 mg/cm3 density modulation. Based on the fact that regions of tumor growth have an increased number density of cell nuclei, and hence of the higher z element phosphorus, it may become possible to detect very early neural "microtumors" through increases of average density on the order of 10 to 15 mg/cm3 by using this method. PMID:9876126

  20. Noise texture and signal detectability in propagation-based x-ray phase-contrast tomography

    SciTech Connect

    Chou, Cheng-Ying; Anastasio, Mark A.

    2010-01-15

    Purpose: X-ray phase-contrast tomography (PCT) is a rapidly emerging imaging modality for reconstructing estimates of an object's three-dimensional x-ray refractive index distribution. Unlike conventional x-ray computed tomography methods, the statistical properties of the reconstructed images in PCT remain unexplored. The purpose of this work is to quantitatively investigate noise propagation in PCT image reconstruction. Methods: The authors derived explicit expressions for the autocovariance of the reconstructed absorption and refractive index images to characterize noise texture and understand how the noise properties are influenced by the imaging geometry. Concepts from statistical detection theory were employed to understand how the imaging geometry-dependent statistical properties affect the signal detection performance in a signal-known-exactly/background-known-exactly task. Results: The analytical formulas for the phase and absorption autocovariance functions were implemented numerically and compared to the corresponding empirical values, and excellent agreement was found. They observed that the reconstructed refractive images are highly spatially correlated, while the absorption images are not. The numerical results confirm that the strength of the covariance is scaled by the detector spacing. Signal detection studies were conducted, employing a numerical observer. The detection performance was found to monotonically increase as the detector-plane spacing was increased. Conclusions: The authors have conducted the first quantitative investigation of noise propagation in PCT image reconstruction. The reconstructed refractive images were found to be highly spatially correlated, while absorption images were not. This is due to the presence of a Fourier space singularity in the reconstruction formula for the refraction images. The statistical analysis may facilitate the use of task-based image quality measures to further develop and optimize this emerging

  1. Triggering of leukocytes by phase contrast in imaging cytometry with scanning fluorescence microscope (SFM)

    NASA Astrophysics Data System (ADS)

    Bocsi, József; Pierzchalski, Arkadiusz; Marecka, Monika; Malkusch, Wolf; Tárnok, Attila

    2009-02-01

    Slide-based cytometry (SBC) leads to breakthrough in cytometry of cells in tissues, culture and suspension. Carl Zeiss Imaging Solutions' new automated SFM combines imaging with cytometry. A critical step in image analysis is selection of appropriate triggering signal to detect all objects. Without correct target cell definition analysis is hampered. DNA-staining is among the most common triggering signals. However, the majority of DNA-dyes yield massive spillover into other fluorescence channels limiting their application. By microscopy objects of >5μm diameter can be easily detected by phase-contrast signal (PCS) without any staining. Aim was to establish PCS - triggering for cell identification. Axio Imager.Z1 motorized SFM was used (high-resolution digital camera, AxioCam MRm; AxioVision software: automatic multi-channel scanning, analysis). Leukocytes were stained with FITC (CD4, CD8) and APC (CD3) labelled antibodies in combinations using whole blood method. Samples were scanned in three channels (PCS/FITC/APC). Exposition-times for PCS were set as low as possible; the detection efficiency was verified by fluorescence. CD45-stained leukocytes were counted and compared to the number of PCS detected events. Leukocyte subtyping was compared with other cytometers. In focus the PCS of cells showed ring-form that was not optimal for cell definition. Out of focus PCS allows more effective qualitative and quantitative cell analyses. PCS was an accurate triggering signal for leukocytes enabling cell counting and discrimination of leukocytes from platelets. Leukocyte subpopulation frequencies were comparable to those obtained by other cytometers. In conclusion PCS is a suitable trigger-signal not interfering with fluorescence detection.

  2. Quantitative imaging of the microbubble concentrations by using an in-line phase contrast tomosynthesis prototype: a preliminary phantom study

    NASA Astrophysics Data System (ADS)

    Wu, Di; Ghani, Muhammad U.; Wong, Molly D.; Li, Yuhua; Yang, Kai; Chen, Wei R.; Zheng, Bin; Liu, Hong

    2016-03-01

    The purpose of this study is to demonstrate the feasibility of using a high-energy in-line phase contrast tomosynthesis system to quantitatively imaging microbubbles in a tissue simulating phantom under a limited radiation dose. The imaging system used in the investigation was a bench top in-line phase contrast tomosynthesis prototype operated under 120 kVp tube voltage and 0.5 mA tube current. A prime beam filter made of 2.3 mm Cu, 0.8 mm Pb and 1.0 mm Al was employed to obtain as large as possible portion of x-ray photon energy higher than 60 keV. The tissue simulating phantom was built by three acrylic slabs and a wax slab to mimic a 40 mm thick compressed breast. There were two tiny-sized structures with average 1 mm depth engraved on the two different layers. The microbubble suspensions with different concentrations were injected into those tiny structures. The inline phase contrast angular projections acquired were used to reconstruct the in-plane slices of the tiny structures on different layers. The CNRs vs microbubble concentrations were investigated. As the result, the microbubble suspensions were clearly visible, showing higher CNR when compared with the areas with no microbubble. Furthermore, a monotonously increasing relation between CNRs and microbubble concentrations was observed after calculating the area CNR of the phase contrast tomosynthesis slices.

  3. Small-animal microangiography using phase-contrast X-ray imaging and gas as contrast agent

    NASA Astrophysics Data System (ADS)

    Lundström, Ulf; Larsson, Daniel H.; Westermark, Ulrica K.; Burvall, Anna; Hertz, Hans M.

    2014-03-01

    We use propagation-based phase-contrast X-ray imaging with gas as contrast agent to visualize the microvasculature in small animals like mice and rats. The radiation dose required for absorption X-ray imaging is proportional to the minus fourth power of the structure size to be detected. This makes small vessels impossible to image at reasonable radiation doses using the absorption of conventional iodinated contrast agents. Propagation-based phase contrast gives enhanced contrast for high spatial frequencies by moving the detector away from the sample to let phase variations in the transmitted X-rays develop into intensity variations at the detector. Blood vessels are normally difficult to observe in phase contrast even with iodinated contrast agents as the density difference between blood and most tissues is relatively small. By injecting gas into the blood stream this density difference can be greatly enhanced giving strong phase contrast. One possible gas to use is carbon dioxide, which is a clinically accepted X-ray contrast agent. The gas is injected into the blood stream of patients to temporarily displace the blood in a region and thereby reduce the X-ray absorption in the blood vessels. We have shown that this method can be used to image blood vessels down to 8 μm in diameter in mouse ears. The low dose requirements of this method indicate a potential for live small-animal imaging and longitudinal studies of angiogenesis.

  4. USE OF IMMUNOFLUORESCENCE AND PHASE-CONTRAST MICROSCOPY FOR DETECTION AND IDENTIFICATION OF 'GIARDIA' CYSTS IN WATER SAMPLES

    EPA Science Inventory

    A method was developed in which indirect immunofluorescence and phase-contrast microscopy are used for rapid detection and identification of Giardia cysts in raw and finished water supplies. When anti-Giardia cyst antiserum and fluorescein conjugate were applied to known Giardia ...

  5. Estimation of age based on tooth cementum annulations: A comparative study using light, polarized, and phase contrast microscopy

    PubMed Central

    Kaur, Prabhpreet; Astekar, Madhusudan; Singh, Jappreet; Arora, Karandeep Singh; Bhalla, Gagandeep

    2015-01-01

    Context: The identification of living or deceased persons using unique traits and characteristics of the teeth and jaws is a cornerstone of forensic science. Teeth have been used to estimate age both in the young and old, as well as in the living and dead. Gradual structural changes in teeth throughout life are the basis for age estimation. Tooth cementum annulation (TCA) is a microscopic method for the determination of an individual's age based on the analysis of incremental lines of cementum. Aim: To compare ages estimated using incremental lines of cementum as visualized by bright field microscopy, polarized microscopy, and phase contrast microscopy with the actual age of subject and to determine accuracy and feasibility of the method used. Materials and Methods: Cementum annulations of 60 permanent teeth were analyzed after longitudinal ground sections were made in the mesiodistal plane. The incremental lines were counted manually using a light, polarized and phase contrast microscopy. Ages were estimated and then compared with the actual age of individual. Statistical Analysis: Analysis of variance (ANOVA), Student's t-test, the Pearson product-moment corre (PPMCC) and regression analysis were performed. Results: PPMCC value r = 0.347, 0.542 and 0.989 were obtained using light, polarized and phase contrast microscopy methods respectively. Conclusion: It was concluded that incremental lines of cementum were most clearly visible under a phase contrast microscope, followed by a polarized microscope, and then a light microscope when used for age estimation. PMID:26816462

  6. Hard X-Ray Phase-Contrast Imaging for Medical Applications — Physicist's Dream or Radiologist's Mainstream?

    NASA Astrophysics Data System (ADS)

    Wilkins, S. W.; Gureyev, T. E.; Mayo, S. C.; Nesterets, Ya. I.; Paganin, D. M.; Pogany, A.; Stevenson, A. W.

    2007-03-01

    We briefly review currently practiced methods of X-ray phase contrast imaging and consider some of their relative features, especially in regard to applicability to clinical medical studies. Various related technological issues and promising future areas of development are also briefly discussed.

  7. Decompressive craniectomy arrests pulsatile aqueductal CSF flux: An in vivo demonstration using phase-contrast MRI. Case report.

    PubMed

    Scollato, Antonio; Gallina, Pasquale; Bahl, Gautam; Di Lorenzo, Nicola

    2015-06-01

    We give a case study demonstration, using aqueductal cerebrospinal fluid (CSF) stroke volume quantification with phase-contrast magnetic resonance imaging, of a large opening in the rigid cranium by a decompressive craniectomy and its subsequent closure by bone flap repositioning resulted in the arrest and subsequent restoration of aqueductal CSF flow. PMID:25958958

  8. Experimental Realisation of High-sensitivity Laboratory X-ray Grating-based Phase-contrast Computed Tomography

    NASA Astrophysics Data System (ADS)

    Birnbacher, Lorenz; Willner, Marian; Velroyen, Astrid; Marschner, Mathias; Hipp, Alexander; Meiser, Jan; Koch, Frieder; Schröter, Tobias; Kunka, Danays; Mohr, Jürgen; Pfeiffer, Franz; Herzen, Julia

    2016-04-01

    The possibility to perform high-sensitivity X-ray phase-contrast imaging with laboratory grating-based phase-contrast computed tomography (gbPC-CT) setups is of great interest for a broad range of high-resolution biomedical applications. However, achieving high sensitivity with laboratory gbPC-CT setups still poses a challenge because several factors such as the reduced flux, the polychromaticity of the spectrum, and the limited coherence of the X-ray source reduce the performance of laboratory gbPC-CT in comparison to gbPC-CT at synchrotron facilities. In this work, we present our laboratory X-ray Talbot-Lau interferometry setup operating at 40 kVp and describe how we achieve the high sensitivity yet unrivalled by any other laboratory X-ray phase-contrast technique. We provide the angular sensitivity expressed via the minimum resolvable refraction angle both in theory and experiment, and compare our data with other differential phase-contrast setups. Furthermore, we show that the good stability of our high-sensitivity setup allows for tomographic scans, by which even the electron density can be retrieved quantitatively as has been demonstrated in several preclinical studies.

  9. Measurements and simulations analysing the noise behaviour of grating-based X-ray phase-contrast imaging

    NASA Astrophysics Data System (ADS)

    Weber, T.; Bartl, P.; Durst, J.; Haas, W.; Michel, T.; Ritter, A.; Anton, G.

    2011-08-01

    In the last decades, phase-contrast imaging using a Talbot-Lau grating interferometer is possible even with a low-brilliance X-ray source. With the potential of increasing the soft-tissue contrast, this method is on its way into medical imaging. For this purpose, the knowledge of the underlying physics of this technique is necessary.With this paper, we would like to contribute to the understanding of grating-based phase-contrast imaging by presenting results on measurements and simulations regarding the noise behaviour of the differential phases.These measurements were done using a microfocus X-ray tube with a hybrid, photon-counting, semiconductor Medipix2 detector. The additional simulations were performed by our in-house developed phase-contrast simulation tool “SPHINX”, combining both wave and particle contributions of the simulated photons.The results obtained by both of these methods show the same behaviour. Increasing the number of photons leads to a linear decrease of the standard deviation of the phase. The number of used phase steps has no influence on the standard deviation, if the total number of photons is held constant.Furthermore, the probability density function (pdf) of the reconstructed differential phases was analysed. It turned out that the so-called von Mises distribution is the physically correct pdf, which was also confirmed by measurements.This information advances the understanding of grating-based phase-contrast imaging and can be used to improve image quality.

  10. Study of phase contrast imaging for carbon fiber, polystyrene and lung tissue using monochromatic and polychromatic X-ray sources

    NASA Astrophysics Data System (ADS)

    Yadav, P. S.; Kashyap, Yogesh; Sarkar, P. S.; Sinha, Amar; Godwal, B. K.

    2006-08-01

    Phase contrast imaging is a new method of radiography in which the information of change in phase of the X-rays as it passes through the object gets reflected in the intensity. This leads to a better sensitivity and contrast than the conventional absorption radiography. In this paper we discuss the simulation studies of phase contrast imaging using monochromatic and polychromatic X-ray point source for simple two- and three-dimensional objects like circular and spherical objects (made up of carbon-fiber, polystyrene and lung tissue). The advantages of refraction contrast images are discussed in terms of contrast and resolution, and a comparison is made with absorption images. The result obtained shows considerable improvement in contrast with phase contrast imaging as compared to conventional absorption radiography. These results also guide us in proper selection of source to object distance, object to detector distance, etc. These results are proposed to be used in our experiment on phase contrast imaging with microfocus X-rays. The technique is going to be very useful in improving the resolution in the X-ray imaging for the composites, and in detection of cracks at micron level resolution. Moreover, if the doses can be controlled by proper selection of the detector or the source, it can have clinical application in the mammography.

  11. Performance analysis of the attenuation-partition based iterative phase retrieval algorithm for in-line phase-contrast imaging

    PubMed Central

    Yan, Aimin; Wu, Xizeng; Liu, Hong

    2010-01-01

    The phase retrieval is an important task in x-ray phase contrast imaging. The robustness of phase retrieval is especially important for potential medical imaging applications such as phase contrast mammography. Recently the authors developed an iterative phase retrieval algorithm, the attenuation-partition based algorithm, for the phase retrieval in inline phase-contrast imaging [1]. Applied to experimental images, the algorithm was proven to be fast and robust. However, a quantitative analysis of the performance of this new algorithm is desirable. In this work, we systematically compared the performance of this algorithm with other two widely used phase retrieval algorithms, namely the Gerchberg-Saxton (GS) algorithm and the Transport of Intensity Equation (TIE) algorithm. The systematical comparison is conducted by analyzing phase retrieval performances with a digital breast specimen model. We show that the proposed algorithm converges faster than the GS algorithm in the Fresnel diffraction regime, and is more robust against image noise than the TIE algorithm. These results suggest the significance of the proposed algorithm for future medical applications with the x-ray phase contrast imaging technique. PMID:20720992

  12. Experimental Realisation of High-sensitivity Laboratory X-ray Grating-based Phase-contrast Computed Tomography

    PubMed Central

    Birnbacher, Lorenz; Willner, Marian; Velroyen, Astrid; Marschner, Mathias; Hipp, Alexander; Meiser, Jan; Koch, Frieder; Schröter, Tobias; Kunka, Danays; Mohr, Jürgen; Pfeiffer, Franz; Herzen, Julia

    2016-01-01

    The possibility to perform high-sensitivity X-ray phase-contrast imaging with laboratory grating-based phase-contrast computed tomography (gbPC-CT) setups is of great interest for a broad range of high-resolution biomedical applications. However, achieving high sensitivity with laboratory gbPC-CT setups still poses a challenge because several factors such as the reduced flux, the polychromaticity of the spectrum, and the limited coherence of the X-ray source reduce the performance of laboratory gbPC-CT in comparison to gbPC-CT at synchrotron facilities. In this work, we present our laboratory X-ray Talbot-Lau interferometry setup operating at 40 kVp and describe how we achieve the high sensitivity yet unrivalled by any other laboratory X-ray phase-contrast technique. We provide the angular sensitivity expressed via the minimum resolvable refraction angle both in theory and experiment, and compare our data with other differential phase-contrast setups. Furthermore, we show that the good stability of our high-sensitivity setup allows for tomographic scans, by which even the electron density can be retrieved quantitatively as has been demonstrated in several preclinical studies. PMID:27040492

  13. Characterization of an x-ray phase contrast imaging system based on the miniature synchrotron MIRRORCLE-6X

    SciTech Connect

    Heekeren, Joop van; Kostenko, Alexander; Hanashima, Takayasu; Yamada, Hironari; Stallinga, Sjoerd; Offerman, S. Erik; Vliet, Lucas J. van

    2011-09-15

    Purpose: The implementation of in-line x-ray phase contrast imaging (PCI) for soft-tissue patient imaging is hampered by the lack of a bright and spatially coherent x-ray source that fits into the hospital environment. This article provides a quantitative characterization of the phase-contrast enhancement of a PCI system based on the miniature synchrotron technology MIRRORCLE-6X. Methods: The phase-contrast effect was measured using an edge response of a plexiglass plate as a function of the incident angle of radiation. We have developed a comprehensive x-ray propagation model based on the system's components, properties, and geometry in order to interpret the measurement data. Monte-Carlo simulations are used to estimate the system's spectral properties and resolution. Results: The measured ratio of the detected phase-contrast to the absorption contrast is currently in the range 100% to 200%. Experiments show that with the current implementation of the MIRRORCLE-6X, a target smaller than 30-40 {mu}m does not lead to a larger phase-contrast. The reason for this is that the fraction of x-rays produced by the material (carbon filament and glue) that is used for mounting the target in the electron beam is more than 25% of the total amount of x-rays produced. This increases the apparent source size. The measured phase-contrast is at maximum two times larger than the absorption contrast with the current set-up. Conclusions: Calculations based on our model of the present imaging system predict that the phase-contrast can be up to an order of magnitude larger than the absorption contrast in case the materials used for mounting the target in the electron beam do not (or hardly) produce x-rays. The methods described in this paper provide vital feedback for guiding future modifications to the design of the x-ray target of MIRRORCLE-type system and configuration of the in-line PCI systems in general.

  14. A grating-based single-shot x-ray phase contrast and diffraction method for in vivo imaging

    SciTech Connect

    Bennett, Eric E.; Kopace, Rael; Stein, Ashley F.; Wen Han

    2010-11-15

    Purpose: The purpose of this study is to develop a single-shot version of the grating-based phase contrast x-ray imaging method and demonstrate its capability of in vivo animal imaging. Here, the authors describe the principle and experimental results. They show the source of artifacts in the phase contrast signal and optimal designs that minimize them. They also discuss its current limitations and ways to overcome them. Methods: A single lead grid was inserted midway between an x-ray tube and an x-ray camera in the planar radiography setting. The grid acted as a transmission grating and cast periodic dark fringes on the camera. The camera had sufficient spatial resolution to resolve the fringes. Refraction and diffraction in the imaged object manifested as position shifts and amplitude attenuation of the fringes, respectively. In order to quantify these changes precisely without imposing a fixed geometric relationship between the camera pixel array and the fringes, a spatial harmonic method in the Fourier domain was developed. The level of the differential phase (refraction) contrast as a function of hardware specifications and device geometry was derived and used to guide the optimal placement of the grid and object. Both ex vivo and in vivo images of rodent extremities were collected to demonstrate the capability of the method. The exposure time using a 50 W tube was 28 s. Results: Differential phase contrast images of glass beads acquired at various grid and object positions confirmed theoretical predictions of how phase contrast and extraneous artifacts vary with the device geometry. In anesthetized rats, a single exposure yielded artifact-free images of absorption, differential phase contrast, and diffraction. Differential phase contrast was strongest at bone-soft tissue interfaces, while diffraction was strongest in bone. Conclusions: The spatial harmonic method allowed us to obtain absorption, differential phase contrast, and diffraction images, all from a

  15. In vivo x-ray phase contrast analyzer-based imaging for longitudinal osteoarthritis studies in guinea pigs

    NASA Astrophysics Data System (ADS)

    Coan, Paola; Wagner, Andreas; Bravin, Alberto; Diemoz, Paul C.; Keyriläinen, Jani; Mollenhauer, Juergen

    2010-12-01

    Over the last two decades phase contrast x-ray imaging techniques have been extensively studied for applications in the biomedical field. Published results demonstrate the high capability of these imaging modalities of improving the image contrast of biological samples with respect to standard absorption-based radiography and routinely used clinical imaging techniques. A clear depiction of the anatomic structures and a more accurate disease diagnosis may be provided by using radiation doses comparable to or lower than those used in current clinical methods. In the literature many works show images of phantoms and excised biological samples proving the high sensitivity of the phase contrast imaging methods for in vitro investigations. In this scenario, the applications of the so-called analyzer-based x-ray imaging (ABI) phase contrast technique are particularly noteworthy. The objective of this work is to demonstrate the feasibility of in vivo x-ray ABI phase contrast imaging for biomedical applications and in particular with respect to joint anatomic depiction and osteoarthritis detection. ABI in planar and tomographic modes was performed in vivo on articular joints of guinea pigs in order to investigate the animals with respect to osteoarthritis by using highly monochromatic x-rays of 52 keV and a low noise detector with a pixel size of 47 × 47 µm2. Images give strong evidence of the ability of ABI in depicting both anatomic structures in complex systems as living organisms and all known signs of osteoarthritis with high contrast, high spatial resolution and with an acceptable radiation dose. This paper presents the first proof of principle study of in vivo application of ABI. The technical challenges encountered when imaging an animal in vivo are discussed. This experimental study is an important step toward the study of clinical applications of phase contrast x-ray imaging techniques.

  16. Investigation of the effect of tube voltage and imaging geometry on phase contrast imaging for a micro-CT system

    NASA Astrophysics Data System (ADS)

    Gui, Jianbao; Zou, Jing; Rong, Junyan; Hu, Zhanli; Zhang, Qiyang; Zheng, Hairong; Xia, Dan

    2012-03-01

    Based upon a bench-top micro-CT system, propagation-based phase-contrast imaging has been investigated using insects and a thin plastic sheet. The system mainly includes a micro-focus source with focal spot size of 13-20 μm and a cooled X-ray CCD detector with pixel size of 24 μm. The edge-enhancement effect can be found clearly in the acquired images. With a 0.5 mm thickness plastic edge phantom, the effects of X-ray tube voltage and imaging geometry on the phase-contrast imaging were investigated, and quantitative index, edge-enhancement index (EEI), were also calculated. In our study, an interesting phenomenon was observed that the phase-contrast effect becomes more pronounced as the tube voltage increases from 20 kVp to 90 kVp. Further investigation indicates that smaller focal spot size resulting from the reduction of tube current at higher tube voltage, has caused the unexpected phenomenon. Inferred from our results, phase-contrast effect is insensitive to the tube voltage in the range of 20-90 kVp (widely used in medical diagnosis); however, it is sensitive to the focal spot size. In addition, for the investigation of the effect of imaging geometry, an optimal geometric magnification range of 2.5-4.5 is suggested to get a good phase-contrast imaging for a micro-CT system with source-to-detector distance of 720 mm.

  17. SU-E-J-207: Assessing the Validity of 4D-CT Based Target Volumes and Free Breathing CBCT Localization in Lung Stereotactic Ablative Radiation Therapy (SABR)

    SciTech Connect

    Badkul, R; Pokhrel, D; Jiang, H; Park, J; Wang, F; Kumar, P

    2014-06-01

    -ITV respectively.Motion excursions and centroid positions were within 2mm for 4D-CT and CBCT-ITVs to that of expected values. Conclusion: 4D-CT MIP-ITV and Union-ITV showed very good agreement that validates that ITV can be fast contoured on MIP.Contouring ITV in AIP must be avoided as it significantly underestimates the volume with all excursions. Free breathing CBCT-ITV showed good agreement with AIP-ITV but underestimated the MIP-ITV. Estimation of excursions and centroid values for 4D-CT and CBCT were in good agreement with expected values.

  18. Limited-angle tomography for analyzer-based phase-contrast x-ray imaging

    NASA Astrophysics Data System (ADS)

    Majidi, Keivan; Wernick, Miles N.; Li, Jun; Muehleman, Carol; Brankov, Jovan G.

    2014-07-01

    Multiple-image radiography (MIR) is an analyzer-based phase-contrast x-ray imaging method, which is emerging as a potential alternative to conventional radiography. MIR simultaneously generates three planar parametric images containing information about scattering, refraction and attenuation properties of the object. The MIR planar images are linear tomographic projections of the corresponding object properties, which allows reconstruction of volumetric images using computed tomography (CT) methods. However, when acquiring a full range of linear projections around the tissue of interest is not feasible or the scanning time is limited, limited-angle tomography techniques can be used to reconstruct these volumetric images near the central plane, which is the plane that contains the pivot point of the tomographic movement. In this work, we use computer simulations to explore the applicability of limited-angle tomography to MIR. We also investigate the accuracy of reconstructions as a function of number of tomographic angles for a fixed total radiation exposure. We use this function to find an optimal range of angles over which data should be acquired for limited-angle tomography MIR (LAT-MIR). Next, we apply the LAT-MIR technique to experimentally acquired MIR projections obtained in a cadaveric human thumb study. We compare the reconstructed slices near the central plane to the same slices reconstructed by CT-MIR using the full angular view around the object. Finally, we perform a task-based evaluation of LAT-MIR performance for different numbers of angular views, and use template matching to detect cartilage in the refraction image near the central plane. We use the signal-to-noise ratio of this test as the detectability metric to investigate an optimum range of tomographic angles for detecting soft tissues in LAT-MIR. Both results show that there is an optimum range of angular view for data acquisition where LAT-MIR yields the best performance, comparable to CT

  19. Limited-angle tomography for analyzer-based phase-contrast X-ray imaging

    PubMed Central

    Majidi, Keivan; Wernick, Miles N; Li, Jun; Muehleman, Carol; Brankov, Jovan G

    2014-01-01

    Multiple-Image Radiography (MIR) is an analyzer-based phase-contrast X-ray imaging method (ABI), which is emerging as a potential alternative to conventional radiography. MIR simultaneously generates three planar parametric images containing information about scattering, refraction and attenuation properties of the object. The MIR planar images are linear tomographic projections of the corresponding object properties, which allows reconstruction of volumetric images using computed tomography (CT) methods. However, when acquiring a full range of linear projections around the tissue of interest is not feasible or the scanning time is limited, limited-angle tomography techniques can be used to reconstruct these volumetric images near the central plane, which is the plane that contains the pivot point of the tomographic movement. In this work, we use computer simulations to explore the applicability of limited-angle tomography to MIR. We also investigate the accuracy of reconstructions as a function of number of tomographic angles for a fixed total radiation exposure. We use this function to find an optimal range of angles over which data should be acquired for limited-angle tomography MIR (LAT-MIR). Next, we apply the LAT-MIR technique to experimentally acquired MIR projections obtained in a cadaveric human thumb study. We compare the reconstructed slices near the central plane to the same slices reconstructed by CT-MIR using the full angular view around the object. Finally, we perform a task-based evaluation of LAT-MIR performance for different numbers of angular views, and use template matching to detect cartilage in the refraction image near the central plane. We use the signal-to-noise ratio of this test as the detectability metric to investigate an optimum range of tomographic angles for detecting soft tissues in LAT-MIR. Both results show that there is an optimum range of angular view for data acquisition where LAT-MIR yields the best performance, comparable to

  20. Correlation between human observer performance and model observer performance in differential phase contrast CT

    SciTech Connect

    Li, Ke; Garrett, John; Chen, Guang-Hong

    2013-11-15

    Purpose: With the recently expanding interest and developments in x-ray differential phase contrast CT (DPC-CT), the evaluation of its task-specific detection performance and comparison with the corresponding absorption CT under a given radiation dose constraint become increasingly important. Mathematical model observers are often used to quantify the performance of imaging systems, but their correlations with actual human observers need to be confirmed for each new imaging method. This work is an investigation of the effects of stochastic DPC-CT noise on the correlation of detection performance between model and human observers with signal-known-exactly (SKE) detection tasks.Methods: The detectabilities of different objects (five disks with different diameters and two breast lesion masses) embedded in an experimental DPC-CT noise background were assessed using both model and human observers. The detectability of the disk and lesion signals was then measured using five types of model observers including the prewhitening ideal observer, the nonprewhitening (NPW) observer, the nonprewhitening observer with eye filter and internal noise (NPWEi), the prewhitening observer with eye filter and internal noise (PWEi), and the channelized Hotelling observer (CHO). The same objects were also evaluated by four human observers using the two-alternative forced choice method. The results from the model observer experiment were quantitatively compared to the human observer results to assess the correlation between the two techniques.Results: The contrast-to-detail (CD) curve generated by the human observers for the disk-detection experiments shows that the required contrast to detect a disk is inversely proportional to the square root of the disk size. Based on the CD curves, the ideal and NPW observers tend to systematically overestimate the performance of the human observers. The NPWEi and PWEi observers did not predict human performance well either, as the slopes of their CD

  1. Phase-contrast magnetic resonance imaging reveals net retrograde aqueductal flow in idiopathic normal pressure hydrocephalus.

    PubMed

    Ringstad, Geir; Emblem, Kyrre Eeg; Eide, Per Kristian

    2016-06-01

    OBJECT The objective of this study was to assess the net aqueductal stroke volume (ASV) and CSF aqueductal flow rate derived from phase-contrast MRI (PC-MRI) in patients with probable idiopathic normal pressure hydrocephalus (iNPH) before and after ventriculoperitoneal shunt surgery, and to compare observations with intracranial pressure (ICP) scores. METHODS PC-MRI at the level of the sylvian aqueduct was undertaken in patients undergoing assessment for probable iNPH. Aqueductal flow in the craniocaudal direction was defined as positive, or antegrade flow, and net ASV was calculated by subtracting retrograde from antegrade aqueductal flow. Aqueductal flow rate per minute was calculated by multiplying net ASV by heart rate. During the same hospital admission, clinical examination was performed using NPH score and overnight continuous ICP monitoring. Twelve patients were followed prospectively 12 months after shunt placement with clinical assessment and a second PC-MRI. The study also included 2 healthy controls. RESULTS Among 21 patients examined for iNPH, 17 (81%) received a shunt (shunt group), and 4 were treated conservatively (conservative group). Among the patients with shunts, a clinical improvement was observed in 16 (94%) of the 17. Net ASV was negative in 16 (76%) of 21 patients before shunt placement and in 5 (42%) of 12 patients after shunt placement, and increased from a median of -5 μl (range -175 to 27 μl) to a median of 1 μl (range -61 to 30 μl; p = 0.04). Among the 12 patients with PC-MRI after shunt placement, 11 were shunt responders, and in 9 of these 11 either a reduced magnitude of retrograde aqueductal flow, or a complete reversal from retrograde to antegrade flow, occurred. Net ASV was significantly lower in the shunt group than in the conservative group (p = 0.01). The aqueductal flow rate increased from -0.56 ml/min (range -12.78 to 0.58 ml/min) to 0.06 ml/min (range -4.51 to 1.93 ml/min; p = 0.04) after shunt placement. CONCLUSIONS In

  2. A theoretical study on phase-contrast mammography with Thomson-scattering x-ray sources

    SciTech Connect

    De Caro, Liberato; Giannini, Cinzia; Bellotti, Roberto; Tangaro, Sabina

    2009-10-15

    Purpose: The x-ray transmitted beam from any material/tissue depends on the complex refractive index (n=1-{delta}+i{beta}), where {delta} is responsible for the phase shift and {beta} is for the beam attenuation. Although for human tissues, the {delta} cross section is about 1000 times greater than the {beta} ones in the x-ray energy range from 10 to 150 keV, the gain in breast tumor visualization of phase-contrast mammography (PCM) with respect to absorption contact imaging (AI) is limited by the maximum dose that can be delivered to the patient. Moreover, in-line PC imaging (PCI) is the simplest experimental mode among all available x-ray PCI techniques since no optics are needed. The latter is a fundamental requirement in order to transfer the results of laboratory research into hospitals. Alternative to synchrotron radiation sources, the implementation of relativistic Thomson-scattering (TS) x-ray sources is particularly suitable for hospital use because of their high peak brightness within a relatively compact and affordable system. In this work, the possibility to realize PCM using a TS source in a hospital environment is studied, accounting for the effect of a finite deliverable dose on the PC visibility enhancement with respect to AI. Methods: The contrast-to-noise ratio of tumor-tissue lesions in PCM has been studied on the bases of a recent theoretical model, describing image contrast formation by means of both wave-optical theory and the mutual coherence formalism. The latter is used to describe the evolution, during wave propagation, of the coherence of the wave field emitted by a TS source. The contrast-to-noise ratio for both PCI and AI has been analyzed in terms of tumor size, beam energy, detector, and source distances, studying optimal conditions for performing PCM. Regarding other relevant factors which could influence ''tumor'' visibility, the authors have assumed simplified conditions such as a spherical shape description of the tumor inclusion

  3. Contrast transfer functions for Zernike phase contrast in full-field transmission hard X-ray microscopy.

    PubMed

    Yang, Yang; Cheng, Yin; Heine, Ruth; Baumbach, Tilo

    2016-03-21

    Full-field transmission hard X-ray microscopy (TXM) has been widely applied to study morphology and structures with high spatial precision and to dynamic processes. Zernike phase contrast (ZPC) in hard X-ray TXM is often utilized to get an in-line phase contrast enhancement for weak-absorbing materials with little contrast differences. Here, following forward image formation, we derive and simplify the contrast transfer functions (CTFs) of the Zernike phase imaging system in TXM based on a linear space-shift-invariant imaging mode under certain approximations. The CTFs in ZPC in their simplified forms show a high similarity to the one in free-space propagation X-ray imaging systems. PMID:27136800

  4. Phase contrast without phase plates and phase rings--optical solutions for improved imaging of phase structures.

    PubMed

    Piper, Timm; Piper, Jörg

    2013-10-01

    Using the optical methods described, phase specimens can be observed with a modified light microscope in enhanced clarity, purified from typical artifacts which are apparent in standard phase contrast illumination. In particular, haloing and shade-off are absent, lateral and vertical resolution are maximized and the image quality remains constant even in problematic preparations which cannot be well examined in normal phase contrast, such as specimens beyond a critical thickness or covered by obliquely situated cover slips. The background brightness and thus the range of contrast can be continuously modulated and specimens can be illuminated in concentric-peripheral, axial or paraxial light. Additional contrast effects can be achieved by spectral color separation. Normal glass or mirror lenses can be used; they do not need to be fitted with a phase plate or a phase ring. The methods described should be of general interest for all disciplines using phase microscopy. PMID:23913620

  5. Quantitative Three-Dimensional Imaging of Lipid, Protein, and Water Contents via X-Ray Phase-Contrast Tomography.

    PubMed

    Willner, Marian; Viermetz, Manuel; Marschner, Mathias; Scherer, Kai; Braun, Christian; Fingerle, Alexander; Noël, Peter; Rummeny, Ernst; Pfeiffer, Franz; Herzen, Julia

    2016-01-01

    X-ray phase-contrast computed tomography is an emerging imaging technology with powerful capabilities for three-dimensional (3D) visualization of weakly absorbing objects such as biological soft tissues. This technique is an extension of existing X-ray applications because conventional attenuation-contrast images are simultaneously acquired. The complementary information provided by both the contrast modalities suggests that enhanced material characterization is possible when performing combined data analysis. In this study, we describe how protein, lipid, and water concentrations in each 3D voxel can be quantified by vector decomposition. Experimental results of dairy products, porcine fat and rind, and different human soft tissue types are presented. The results demonstrate the potential of phase-contrast imaging as a new analysis tool. The 3D representations of protein, lipid, and water contents open up new opportunities in the fields of biology, medicine, and food science. PMID:27003308

  6. Aerosol-induced lung injuries observed by synchrotron radiation X-ray phase-contrast imaging technique

    NASA Astrophysics Data System (ADS)

    Yue, Weisheng; Zhang, Guilin; Liu, Ping; Sun, Jianqi; Hwu, Yeukuang; Je, Jung Ho; Tan, Mingguang; Li, Yan

    2007-09-01

    Adverse health effects are associated with the inhalation of a variety of atmospheric particles. To study the lung injuries caused by aerosol PM2.5, synchrotron radiation (SR) X-ray phase-contrast imaging technique was used. Nude mice were inoculated with PM2.5 samples collected from suburban area (JD), industrial area (BS) and traffic tunnel (DPQ) of Shanghai. From X-ray phase-contrast images of lung tissues, apart from blood vessels and structures of alveoli, even hemorrhage spots of several microns caused by the inflammation were clearly observed. The studies showed that the PM2.5 samples collected from the traffic tunnel (DPQ) produced higher level of lung injury, followed by the aerosol samples collected from industrial area (BS) and suburban area (JD). Our studies also helped us to understand the process of lung injuries caused by aerosol particles.

  7. Quantitative Three-Dimensional Imaging of Lipid, Protein, and Water Contents via X-Ray Phase-Contrast Tomography

    PubMed Central

    Willner, Marian; Viermetz, Manuel; Marschner, Mathias; Scherer, Kai; Braun, Christian; Fingerle, Alexander; Noël, Peter; Rummeny, Ernst; Pfeiffer, Franz; Herzen, Julia

    2016-01-01

    X-ray phase-contrast computed tomography is an emerging imaging technology with powerful capabilities for three-dimensional (3D) visualization of weakly absorbing objects such as biological soft tissues. This technique is an extension of existing X-ray applications because conventional attenuation-contrast images are simultaneously acquired. The complementary information provided by both the contrast modalities suggests that enhanced material characterization is possible when performing combined data analysis. In this study, we describe how protein, lipid, and water concentrations in each 3D voxel can be quantified by vector decomposition. Experimental results of dairy products, porcine fat and rind, and different human soft tissue types are presented. The results demonstrate the potential of phase-contrast imaging as a new analysis tool. The 3D representations of protein, lipid, and water contents open up new opportunities in the fields of biology, medicine, and food science. PMID:27003308

  8. Realistic wave-optics simulation of X-ray phase-contrast imaging at a human scale

    NASA Astrophysics Data System (ADS)

    Sung, Yongjin; Segars, W. Paul; Pan, Adam; Ando, Masami; Sheppard, Colin J. R.; Gupta, Rajiv

    2015-07-01

    X-ray phase-contrast imaging (XPCI) can dramatically improve soft tissue contrast in X-ray medical imaging. Despite worldwide efforts to develop novel XPCI systems, a numerical framework to rigorously predict the performance of a clinical XPCI system at a human scale is not yet available. We have developed such a tool by combining a numerical anthropomorphic phantom defined with non-uniform rational B-splines (NURBS) and a wave optics-based simulator that can accurately capture the phase-contrast signal from a human-scaled numerical phantom. Using a synchrotron-based, high-performance XPCI system, we provide qualitative comparison between simulated and experimental images. Our tool can be used to simulate the performance of XPCI on various disease entities and compare proposed XPCI systems in an unbiased manner.

  9. Realistic wave-optics simulation of X-ray phase-contrast imaging at a human scale

    PubMed Central

    Sung, Yongjin; Segars, W. Paul; Pan, Adam; Ando, Masami; Sheppard, Colin J. R.; Gupta, Rajiv

    2015-01-01

    X-ray phase-contrast imaging (XPCI) can dramatically improve soft tissue contrast in X-ray medical imaging. Despite worldwide efforts to develop novel XPCI systems, a numerical framework to rigorously predict the performance of a clinical XPCI system at a human scale is not yet available. We have developed such a tool by combining a numerical anthropomorphic phantom defined with non-uniform rational B-splines (NURBS) and a wave optics-based simulator that can accurately capture the phase-contrast signal from a human-scaled numerical phantom. Using a synchrotron-based, high-performance XPCI system, we provide qualitative comparison between simulated and experimental images. Our tool can be used to simulate the performance of XPCI on various disease entities and compare proposed XPCI systems in an unbiased manner. PMID:26169570

  10. Realistic wave-optics simulation of X-ray phase-contrast imaging at a human scale.

    PubMed

    Sung, Yongjin; Segars, W Paul; Pan, Adam; Ando, Masami; Sheppard, Colin J R; Gupta, Rajiv

    2015-01-01

    X-ray phase-contrast imaging (XPCI) can dramatically improve soft tissue contrast in X-ray medical imaging. Despite worldwide efforts to develop novel XPCI systems, a numerical framework to rigorously predict the performance of a clinical XPCI system at a human scale is not yet available. We have developed such a tool by combining a numerical anthropomorphic phantom defined with non-uniform rational B-splines (NURBS) and a wave optics-based simulator that can accurately capture the phase-contrast signal from a human-scaled numerical phantom. Using a synchrotron-based, high-performance XPCI system, we provide qualitative comparison between simulated and experimental images. Our tool can be used to simulate the performance of XPCI on various disease entities and compare proposed XPCI systems in an unbiased manner. PMID:26169570

  11. Bilateral filtering using the full noise covariance matrix applied to x-ray phase-contrast computed tomography

    NASA Astrophysics Data System (ADS)

    Allner, S.; Koehler, T.; Fehringer, A.; Birnbacher, L.; Willner, M.; Pfeiffer, F.; Noël, P. B.

    2016-05-01

    The purpose of this work is to develop an image-based de-noising algorithm that exploits complementary information and noise statistics from multi-modal images, as they emerge in x-ray tomography techniques, for instance grating-based phase-contrast CT and spectral CT. Among the noise reduction methods, image-based de-noising is one popular approach and the so-called bilateral filter is a well known algorithm for edge-preserving filtering. We developed a generalization of the bilateral filter for the case where the imaging system provides two or more perfectly aligned images. The proposed generalization is statistically motivated and takes the full second order noise statistics of these images into account. In particular, it includes a noise correlation between the images and spatial noise correlation within the same image. The novel generalized three-dimensional bilateral filter is applied to the attenuation and phase images created with filtered backprojection reconstructions from grating-based phase-contrast tomography. In comparison to established bilateral filters, we obtain improved noise reduction and at the same time a better preservation of edges in the images on the examples of a simulated soft-tissue phantom, a human cerebellum and a human artery sample. The applied full noise covariance is determined via cross-correlation of the image noise. The filter results yield an improved feature recovery based on enhanced noise suppression and edge preservation as shown here on the example of attenuation and phase images captured with grating-based phase-contrast computed tomography. This is supported by quantitative image analysis. Without being bound to phase-contrast imaging, this generalized filter is applicable to any kind of noise-afflicted image data with or without noise correlation. Therefore, it can be utilized in various imaging applications and fields.

  12. Investigation of gastric cancers in nude mice using X-ray in-line phase contrast imaging

    PubMed Central

    2014-01-01

    Background This paper is to report the new imaging of gastric cancers without the use of imaging agents. Both gastric normal regions and gastric cancer regions can be distinguished by using the principal component analysis (PCA) based on the gray level co-occurrence matrix (GLCM). Methods Human gastric cancer BGC823 cells were implanted into the stomachs of nude mice. Then, 3, 5, 7, 9 or 11 days after cancer cells implantation, the nude mice were sacrificed and their stomachs were removed. X-ray in-line phase contrast imaging (XILPCI), an X-ray phase contrast imaging method, has greater soft tissue contrast than traditional absorption radiography and generates higher-resolution images. The gastric specimens were imaged by an XILPCIs’ charge coupled device (CCD) of 9 μm image resolution. The PCA of the projective images’ region of interests (ROIs) based on GLCM were extracted to discriminate gastric normal regions and gastric cancer regions. Different stages of gastric cancers were classified by using support vector machines (SVMs). Results The X-ray in-line phase contrast images of nude mice gastric specimens clearly show the gastric architectures and the details of the early gastric cancers. The phase contrast computed tomography (CT) images of nude mice gastric cancer specimens are better than the traditional absorption CT images without the use of imaging agents. The results of the PCA of the texture parameters based on GLCM of normal regions is (F1 + F2) > 8.5, but those of cancer regions is (F1 + F2) < 8.5. The classification accuracy is 83.3% that classifying gastric specimens into different stages using SVMs. Conclusions This is a very preliminary feasibility study. With further researches, XILPCI could become a noninvasive method for future the early detection of gastric cancers or medical researches. PMID:25060352

  13. Increasing the field of view of x-ray phase contrast imaging using stitched gratings on low absorbent carriers

    NASA Astrophysics Data System (ADS)

    Meiser, J.; Amberger, M.; Willner, M.; Kunka, D.; Meyer, P.; Koch, F.; Hipp, A.; Walter, M.; Pfeiffer, F.; Mohr, J.

    2014-03-01

    X-ray phase contrast imaging has become a promising biomedical imaging technique for enhancing soft-tissue contrast. In addition to an absorption contrast image it provides two more types of image, a phase contrast and a small-angle scattering contrast image recorded at the same time. In biomedical imaging their combination allows for the conventional investigation of e.g. bone fractures on the one hand and for soft-tissue investigation like cancer detection on the other hand. Among the different methods of X-ray phase contrast imaging the grating based approach, the Talbot-Lau interferometry, has the highest potential for commercial use in biomedical imaging at the moment, because commercially available X-ray sources can be used in a compact setup. In Talbot-Lau interferometers, core elements are phase and absorption gratings with challenging specifications because of their high aspect ratios (structure height over width). For the long grating lamellas structural heights of more than 100 μm together with structural width in the micron range are requested. We are developing a fabrication process based on deep x-ray lithography and electroforming (LIGA) to fabricate these challenging structures. In case of LIGA gratings the structural area is currently limited to several centimeters by several centimeters which limit the field of view in grating based X-ray phase contrast imaging. In order to increase the grating area significantly we are developing a stitching method for gratings using a 625 μm thick silicon wafer as a carrier substrate. In this work we compare the silicon carrier with an alternative one, polyimide, for patient dose reduction and for the use at lower energies in terms of transmission and image reconstruction problems.

  14. Bilateral filtering using the full noise covariance matrix applied to x-ray phase-contrast computed tomography.

    PubMed

    Allner, S; Koehler, T; Fehringer, A; Birnbacher, L; Willner, M; Pfeiffer, F; Noël, P B

    2016-05-21

    The purpose of this work is to develop an image-based de-noising algorithm that exploits complementary information and noise statistics from multi-modal images, as they emerge in x-ray tomography techniques, for instance grating-based phase-contrast CT and spectral CT. Among the noise reduction methods, image-based de-noising is one popular approach and the so-called bilateral filter is a well known algorithm for edge-preserving filtering. We developed a generalization of the bilateral filter for the case where the imaging system provides two or more perfectly aligned images. The proposed generalization is statistically motivated and takes the full second order noise statistics of these images into account. In particular, it includes a noise correlation between the images and spatial noise correlation within the same image. The novel generalized three-dimensional bilateral filter is applied to the attenuation and phase images created with filtered backprojection reconstructions from grating-based phase-contrast tomography. In comparison to established bilateral filters, we obtain improved noise reduction and at the same time a better preservation of edges in the images on the examples of a simulated soft-tissue phantom, a human cerebellum and a human artery sample. The applied full noise covariance is determined via cross-correlation of the image noise. The filter results yield an improved feature recovery based on enhanced noise suppression and edge preservation as shown here on the example of attenuation and phase images captured with grating-based phase-contrast computed tomography. This is supported by quantitative image analysis. Without being bound to phase-contrast imaging, this generalized filter is applicable to any kind of noise-afflicted image data with or without noise correlation. Therefore, it can be utilized in various imaging applications and fields. PMID:27100408

  15. Analytical evaluation of the signal and noise propagation in x-ray differential phase-contrast computed tomography

    NASA Astrophysics Data System (ADS)

    Raupach, Rainer; Flohr, Thomas G.

    2011-04-01

    We analyze the signal and noise propagation of differential phase-contrast computed tomography (PCT) compared with conventional attenuation-based computed tomography (CT) from a theoretical point of view. This work focuses on grating-based differential phase-contrast imaging. A mathematical framework is derived that is able to analytically predict the relative performance of both imaging techniques in the sense of the relative contrast-to-noise ratio for the contrast of any two materials. Two fundamentally different properties of PCT compared with CT are identified. First, the noise power spectra show qualitatively different characteristics implying a resolution-dependent performance ratio. The break-even point is derived analytically as a function of system parameters such as geometry and visibility. A superior performance of PCT compared with CT can only be achieved at a sufficiently high spatial resolution. Second, due to periodicity of phase information which is non-ambiguous only in a bounded interval statistical phase wrapping can occur. This effect causes a collapse of information propagation for low signals which limits the applicability of phase-contrast imaging at low dose.

  16. Quantitative studies on inner interfaces in conical metal joints using hard x-ray inline phase contrast radiography

    SciTech Connect

    Zabler, S.; Rack, T.; Nelson, K.; Rack, A.

    2010-10-15

    Quantitative investigation of micrometer and submicrometer gaps between joining metal surfaces is applied to conical plug-socket connections in dental titanium implants. Microgaps of widths well beyond the resolving power of industrial x-ray systems are imaged by synchrotron phase contrast radiography. Furthermore, by using an analytical model for the relatively simple sample geometry and applying it to numerical forward simulations of the optical Fresnel propagation, we show that quantitative measurements of the microgap width down to 0.1 {mu}m are possible. Image data recorded at the BAMline (BESSY-II light source, Germany) are presented, with the resolving power of the imaging system being 4 {mu}m in absorption mode and {approx}14 {mu}m in phase contrast mode (z{sub 2}=0.74 m). Thus, phase contrast radiography, combined with numerical forward simulations, is capable of measuring the widths of gaps that are two orders of magnitude thinner than the conventional detection limit.

  17. High-resolution, low-dose phase contrast X-ray tomography for 3D diagnosis of human breast cancers.

    PubMed

    Zhao, Yunzhe; Brun, Emmanuel; Coan, Paola; Huang, Zhifeng; Sztrókay, Aniko; Diemoz, Paul Claude; Liebhardt, Susanne; Mittone, Alberto; Gasilov, Sergei; Miao, Jianwei; Bravin, Alberto

    2012-11-01

    Mammography is the primary imaging tool for screening and diagnosis of human breast cancers, but ~10-20% of palpable tumors are not detectable on mammograms and only about 40% of biopsied lesions are malignant. Here we report a high-resolution, low-dose phase contrast X-ray tomographic method for 3D diagnosis of human breast cancers. By combining phase contrast X-ray imaging with an image reconstruction method known as equally sloped tomography, we imaged a human breast in three dimensions and identified a malignant cancer with a pixel size of 92 μm and a radiation dose less than that of dual-view mammography. According to a blind evaluation by five independent radiologists, our method can reduce the radiation dose and acquisition time by ~74% relative to conventional phase contrast X-ray tomography, while maintaining high image resolution and image contrast. These results demonstrate that high-resolution 3D diagnostic imaging of human breast cancers can, in principle, be performed at clinical compatible doses. PMID:23091003

  18. Single shot x-ray phase contrast imaging using a direct conversion microstrip detector with single photon sensitivity

    NASA Astrophysics Data System (ADS)

    Kagias, M.; Cartier, S.; Wang, Z.; Bergamaschi, A.; Dinapoli, R.; Mozzanica, A.; Schmitt, B.; Stampanoni, M.

    2016-06-01

    X-ray phase contrast imaging enables the measurement of the electron density of a sample with high sensitivity compared to the conventional absorption contrast. This is advantageous for the study of dose-sensitive samples, in particular, for biological and medical investigations. Recent developments relaxed the requirement for the beam coherence, such that conventional X-ray sources can be used for phase contrast imaging and thus clinical applications become possible. One of the prominent phase contrast imaging methods, Talbot-Lau grating interferometry, is limited by the manufacturing, alignment, and photon absorption of the analyzer grating, which is placed in the beam path in front of the detector. We propose an alternative improved method based on direct conversion charge integrating detectors, which enables a grating interferometer to be operated without an analyzer grating. Algorithms are introduced, which resolve interference fringes with a periodicity of 4.7 μm recorded with a 25 μm pitch Si microstrip detector (GOTTHARD). The feasibility of the proposed approach is demonstrated by an experiment at the TOMCAT beamline of the Swiss Light Source on a polyethylene sample.

  19. A user-friendly LabVIEW software platform for grating based X-ray phase-contrast imaging.

    PubMed

    Wang, Shenghao; Han, Huajie; Gao, Kun; Wang, Zhili; Zhang, Can; Yang, Meng; Wu, Zhao; Wu, Ziyu

    2015-01-01

    X-ray phase-contrast imaging can provide greatly improved contrast over conventional absorption-based imaging for weakly absorbing samples, such as biological soft tissues and fibre composites. In this study, we introduced an easy and fast way to develop a user-friendly software platform dedicated to the new grating-based X-ray phase-contrast imaging setup at the National Synchrotron Radiation Laboratory of the University of Science and Technology of China. The control of 21 motorized stages, of a piezoelectric stage and of an X-ray tube are achieved with this software, it also covers image acquisition with a flat panel detector for automatic phase stepping scan. Moreover, a data post-processing module for signals retrieval and other custom features are in principle available. With a seamless integration of all the necessary functions in one software package, this platform greatly facilitate users' activities during experimental runs with this grating based X-ray phase contrast imaging setup. PMID:25882730

  20. Optimisation of image reconstruction for phase-contrast x-ray Talbot–Lau imaging with regard to mechanical robustness

    NASA Astrophysics Data System (ADS)

    Seifert, M.; Kaeppler, S.; Hauke, C.; Horn, F.; Pelzer, G.; Rieger, J.; Michel, T.; Riess, C.; Anton, G.

    2016-09-01

    X-ray grating-based phase-contrast imaging opens new opportunities, inter alia, in medical imaging and non-destructive testing. Because, information about the attenuation properties and about the refractive properties of an object are gained simultaneously. Talbot–Lau imaging requires the knowledge of a reference or free-field image. The long-term stability of a Talbot–Lau interferometer is related to the time span of the validity of a measured reference image. It would be desirable to keep the validity of the reference image for a day or longer to improve feasibility of Talbot–Lau imaging. However, for example thermal and other long-term external influences result in drifting effects of the phase images. Therefore, phases are shifting over time and the reference image is not valid for long-term measurements. Thus, artifacts occur in differential phase-contrast images. We developed an algorithm to determine the differential phase-contrast image with the help of just one calibration image, which is valid for a long time-period. With the help of this algorithm, called phase-plane-fit method, it is possible to save measurement-time, as it is not necessary to take a reference image for each measurement. Additionally, transferring the interferometer technique from laboratory setups to conventional imaging systems the necessary rigidity of the system is difficult to achieve. Therefore, short-term effects like vibrations or distortions of the system lead to imperfections within the phase-stepping procedure. Consequently, artifacts occur in all three image modalities (differential phase-contrast image, attenuation image and dark-field image) of Talbot–Lau imaging. This is a problem with regard to the intended use of phase-contrast imaging for example in clinical routine or non-destructive testing. In this publication an algorithm of Vargas et al is applied and complemented to correct inaccurate phase-step positions with the help of a principal component analysis

  1. Optimisation of image reconstruction for phase-contrast x-ray Talbot-Lau imaging with regard to mechanical robustness.

    PubMed

    Seifert, M; Kaeppler, S; Hauke, C; Horn, F; Pelzer, G; Rieger, J; Michel, T; Riess, C; Anton, G

    2016-09-01

    X-ray grating-based phase-contrast imaging opens new opportunities, inter alia, in medical imaging and non-destructive testing. Because, information about the attenuation properties and about the refractive properties of an object are gained simultaneously. Talbot-Lau imaging requires the knowledge of a reference or free-field image. The long-term stability of a Talbot-Lau interferometer is related to the time span of the validity of a measured reference image. It would be desirable to keep the validity of the reference image for a day or longer to improve feasibility of Talbot-Lau imaging. However, for example thermal and other long-term external influences result in drifting effects of the phase images. Therefore, phases are shifting over time and the reference image is not valid for long-term measurements. Thus, artifacts occur in differential phase-contrast images. We developed an algorithm to determine the differential phase-contrast image with the help of just one calibration image, which is valid for a long time-period. With the help of this algorithm, called phase-plane-fit method, it is possible to save measurement-time, as it is not necessary to take a reference image for each measurement. Additionally, transferring the interferometer technique from laboratory setups to conventional imaging systems the necessary rigidity of the system is difficult to achieve. Therefore, short-term effects like vibrations or distortions of the system lead to imperfections within the phase-stepping procedure. Consequently, artifacts occur in all three image modalities (differential phase-contrast image, attenuation image and dark-field image) of Talbot-Lau imaging. This is a problem with regard to the intended use of phase-contrast imaging for example in clinical routine or non-destructive testing. In this publication an algorithm of Vargas et al is applied and complemented to correct inaccurate phase-step positions with the help of a principal component analysis (PCA

  2. Ideal-observer detectability in photon-counting differential phase-contrast imaging using a linear-systems approach

    SciTech Connect

    Fredenberg, Erik; Danielsson, Mats; Stayman, J. Webster; Siewerdsen, Jeffrey H.; Aslund, Magnus

    2012-09-15

    Purpose: To provide a cascaded-systems framework based on the noise-power spectrum (NPS), modulation transfer function (MTF), and noise-equivalent number of quanta (NEQ) for quantitative evaluation of differential phase-contrast imaging (Talbot interferometry) in relation to conventional absorption contrast under equal-dose, equal-geometry, and, to some extent, equal-photon-economy constraints. The focus is a geometry for photon-counting mammography. Methods: Phase-contrast imaging is a promising technology that may emerge as an alternative or adjunct to conventional absorption contrast. In particular, phase contrast may increase the signal-difference-to-noise ratio compared to absorption contrast because the difference in phase shift between soft-tissue structures is often substantially larger than the absorption difference. We have developed a comprehensive cascaded-systems framework to investigate Talbot interferometry, which is a technique for differential phase-contrast imaging. Analytical expressions for the MTF and NPS were derived to calculate the NEQ and a task-specific ideal-observer detectability index under assumptions of linearity and shift invariance. Talbot interferometry was compared to absorption contrast at equal dose, and using either a plane wave or a spherical wave in a conceivable mammography geometry. The impact of source size and spectrum bandwidth was included in the framework, and the trade-off with photon economy was investigated in some detail. Wave-propagation simulations were used to verify the analytical expressions and to generate example images. Results: Talbot interferometry inherently detects the differential of the phase, which led to a maximum in NEQ at high spatial frequencies, whereas the absorption-contrast NEQ decreased monotonically with frequency. Further, phase contrast detects differences in density rather than atomic number, and the optimal imaging energy was found to be a factor of 1.7 higher than for absorption

  3. Ideal-observer detectability in photon-counting differential phase-contrast imaging using a linear-systems approach

    PubMed Central

    Fredenberg, Erik; Danielsson, Mats; Stayman, J. Webster; Siewerdsen, Jeffrey H.; Åslund, Magnus

    2012-01-01

    Purpose: To provide a cascaded-systems framework based on the noise-power spectrum (NPS), modulation transfer function (MTF), and noise-equivalent number of quanta (NEQ) for quantitative evaluation of differential phase-contrast imaging (Talbot interferometry) in relation to conventional absorption contrast under equal-dose, equal-geometry, and, to some extent, equal-photon-economy constraints. The focus is a geometry for photon-counting mammography. Methods: Phase-contrast imaging is a promising technology that may emerge as an alternative or adjunct to conventional absorption contrast. In particular, phase contrast may increase the signal-difference-to-noise ratio compared to absorption contrast because the difference in phase shift between soft-tissue structures is often substantially larger than the absorption difference. We have developed a comprehensive cascaded-systems framework to investigate Talbot interferometry, which is a technique for differential phase-contrast imaging. Analytical expressions for the MTF and NPS were derived to calculate the NEQ and a task-specific ideal-observer detectability index under assumptions of linearity and shift invariance. Talbot interferometry was compared to absorption contrast at equal dose, and using either a plane wave or a spherical wave in a conceivable mammography geometry. The impact of source size and spectrum bandwidth was included in the framework, and the trade-off with photon economy was investigated in some detail. Wave-propagation simulations were used to verify the analytical expressions and to generate example images. Results: Talbot interferometry inherently detects the differential of the phase, which led to a maximum in NEQ at high spatial frequencies, whereas the absorption-contrast NEQ decreased monotonically with frequency. Further, phase contrast detects differences in density rather than atomic number, and the optimal imaging energy was found to be a factor of 1.7 higher than for absorption

  4. Abdominal aortic aneurysm

    MedlinePlus

    ... to the abdomen, pelvis, and legs. An abdominal aortic aneurysm occurs when an area of the aorta becomes ... blood pressure Male gender Genetic factors An abdominal aortic aneurysm is most often seen in males over age ...

  5. Abdominal x-ray

    MedlinePlus

    ... More Abdominal aortic aneurysm Abdominal pain Acute cholecystitis Acute kidney failure Addison disease Adenomyosis Annular pancreas Aplastic anemia Appendicitis Ascariasis Atheroembolic renal disease Biliary atresia Blind loop syndrome Cholangitis Chronic ...

  6. Developing a platform for high-resolution phase contrast imaging of high pressure shock waves in matter

    NASA Astrophysics Data System (ADS)

    Schropp, Andreas; Patommel, Jens; Seiboth, Frank; Arnold, Brice; Galtier, Eric C.; Lee, Hae Ja; Nagler, Bob; Hastings, Jerome B.; Schroer, Christian G.

    2012-10-01

    Current and upcoming X-ray sources, such as the Linac Coherent Light Source (LCLS) at the Stanford Linear Accelerator Center (SLAC, USA), the SPring-8 Angstrom Compact Free Electron Laser (SACLA, Japan), or the X-ray Free Electron Laser (XFEL, Germany) will provide X-ray beams with outstanding properties.1, 2 Short and intense X-ray pulses of about 50 fs time duration and even shorter will push X-ray science to new frontiers such as, e. g., in high-resolution X-ray imaging, high-energy-density physics or in dynamical studies based on pump-probe techniques. Fast processes in matter often require high-resolution imaging capabilities either by magnified imaging in direct space or diffractive imaging in reciprocal space. In both cases highest resolutions require focusing the X-ray beam.3, 4 In order to further develop high-resolution imaging at free-electron laser sources we are planning a platform to carry out high-resolution phase contrast imaging experiments based on Beryllium compound refractive X-ray lenses (Be-CRLs) at the Matter in Extreme Conditions (MEC) endstation of the LCLS. The instrument provides all necessary equipment to induce high pressure shock waves by optical lasers. The propagation of a shock wave is then monitored with an X-ray Free Electron Laser (FEL) pulse by magnified phase contrast imaging. With the CRL optics, X-ray beam sizes in the sub-100nm range are expected, leading to a similar spatial resolution in the direct coherent projection image. The experiment combines different state-of-the art scientific techniques that are currently available at the LCLS. In this proceedings paper we describe the technical developments carried out at the LCLS in order to implement magnified X-ray phase contrast imaging at the MEC endstation.

  7. 3D tracking and phase-contrast imaging by twin-beams digital holographic microscope in microfluidics

    NASA Astrophysics Data System (ADS)

    Miccio, L.; Memmolo, P.; Finizio, A.; Paturzo, M.; Merola, F.; Grilli, S.; Ferraro, P.

    2012-06-01

    A compact twin-beam interferometer that can be adopted as a flexible diagnostic tool in microfluidic platforms is presented. The devise has two functionalities, as explained in the follow, and can be easily integrated in microfluidic chip. The configuration allows 3D tracking of micro-particles and, at same time, furnishes Quantitative Phase-Contrast maps of tracked micro-objects by interference microscopy. Experimental demonstration of its effectiveness and compatibility with biological field is given on for in vitro cells in microfluidic environment. Nowadays, several microfluidic configuration exist and many of them are commercially available, their development is due to the possibility for manipulating droplets, handling micro and nano-objects, visualize and quantify processes occurring in small volumes and, clearly, for direct applications on lab-on-a chip devices. In microfluidic research field, optical/photonics approaches are the more suitable ones because they have various advantages as to be non-contact, full-field, non-invasive and can be packaged thanks to the development of integrable optics. Moreover, phase contrast approaches, adapted to a lab-on-a-chip configurations, give the possibility to get quantitative information with remarkable lateral and vertical resolution directly in situ without the need to dye and/or kill cells. Furthermore, numerical techniques for tracking of micro-objects needs to be developed for measuring velocity fields, trajectories patterns, motility of cancer cell and so on. Here, we present a compact holographic microscope that can ensure, by the same configuration and simultaneously, accurate 3D tracking and quantitative phase-contrast analysis. The system, simple and solid, is based on twin laser beams coming from a single laser source. Through a easy conceptual design, we show how these two different functionalities can be accomplished by the same optical setup. The working principle, the optical setup and the mathematical

  8. Visualisation by high resolution synchrotron X-ray phase contrast micro-tomography of gas films on submerged superhydrophobic leaves.

    PubMed

    Lauridsen, Torsten; Glavina, Kyriaki; Colmer, Timothy David; Winkel, Anders; Irvine, Sarah; Lefmann, Kim; Feidenhans'l, Robert; Pedersen, Ole

    2014-10-01

    Floods can completely submerge terrestrial plants but some wetland species can sustain O2 and CO2 exchange with the environment via gas films forming on superhydrophobic leaf surfaces. We used high resolution synchrotron X-ray phase contrast micro-tomography in a novel approach to visualise gas films on submerged leaves of common cordgrass (Spartina anglica). 3D tomograms enabled a hitherto unmatched level of detail regarding the micro-topography of leaf gas films. Gas films formed only on the superhydrophobic adaxial leaf side (water droplet contact angle, Φ=162°) but not on the abaxial side (Φ=135°). The adaxial side of the leaves of common cordgrass is plicate with a longitudinal system of parallel grooves and ridges and the vast majority of the gas film volume was found in large ∼180μm deep elongated triangular volumes in the grooves and these volumes were connected to each neighbouring groove via a fine network of gas tubules (∼1.7μm diameter) across the ridges. In addition to the gas film retained on the leaf exterior, the X-ray phase contrast micro-tomography also successfully distinguished gas spaces internally in the leaf tissues, and the tissue porosity (gas volume per unit tissue volume) ranged from 6.3% to 20.3% in tip and base leaf segments, respectively. We conclude that X-ray phase contrast micro-tomography is a powerful tool to obtain quantitative data of exterior gas features on biological samples because of the significant difference in electron density between air, biological tissues and water. PMID:25175398

  9. Proof-of-concept demonstration of edge-illumination x-ray phase contrast imaging combined with tomosynthesis

    NASA Astrophysics Data System (ADS)

    Szafraniec, Magdalena B.; Millard, Thomas P.; Ignatyev, Konstantin; Speller, Robert D.; Olivo, Alessandro

    2014-03-01

    In this note we present the first proof-of-concept results on the potential effectiveness of the edge-illumination x-ray phase contrast method (in its ‘coded-aperture’ based lab implementation) combined with tomosynthesis. We believe that, albeit admittedly preliminary (e.g. we only present phantom work), these results deserve early publication in a note primarily for four reasons. First, we fully modelled the imaging acquisition method, and validated the simulation directly with experimental results. This shows that the implementation of the method in the new geometry is understood, and thus that it will be possible to use the model to simulate more complex scenarios in the future. Secondly, we show that a strong phase contrast signal is preserved in the reconstructed tomosynthesis slices: this was a concern, as the high spatial frequency nature of the signal makes it sensitive to any filtration-related procedure. Third, we show that, despite the non-optimized nature of the imaging prototype used, we can perform a full angular scan at acceptable dose levels and with exposure times not excessively distant from what is required by clinical practice. Finally, we discuss how the proposed phase contrast method, unlike other approaches apart from free-space propagation (which however requires a smaller focal spot, thus reducing the flux and increasing exposure times), can be easily implemented in a tomosynthesis geometry suitable for clinical use. In summary, we find that these technical results indicate a high potential for the combination of the two methods. Combining slice separation with detail enhancement provided by phase effects would substantially increase the detectability of small lesions and/or calcifications, which we aim to demonstrate in the next steps of this study.

  10. Microscopic identification of Chinese medicinal materials based on X-ray phase contrast imaging: from qualitative to quantitative

    NASA Astrophysics Data System (ADS)

    Xue, Y.; Liang, Z.; Tan, H.; Ni, L.; Zhao, Z.; Xiao, T.; Xu, H.

    2016-07-01

    Although a variety of methods, ranging from simple morphological examination to physical and chemical analysis, and DNA molecular biology, exist for authenticating Chinese medicinal materials(CMMs), no methods can achieve both the source species identification and quality evaluation of CMMs simultaneously. Furthermore, the methods that are currently available for the identification of CMMs, including both optical and electronic microscopy, usually entail strict requirements for sample preparation or testing environment, such as the slicing of super-thin sections, or processing with specific chemical reagents. These treatments not only damage the CMMs but may also cause some of the original microstructures to be missed. Additionally, they may even yield false results. Owing to the unique penetrating character of X-rays, X-ray phase contrast imaging(XPCI) can be used to realize the inner microstructures of CMMs through nondestructive imaging. With the higher flux and luminance of the third generation of synchrotron radiation facility, XPCI can provides clearer and finer microstructures of CMMs, which are mainly composed of C, H, O, and N elements, with better spatial and density resolutions. For more than ten years, the X-ray imaging group at the Shanghai Institute of Applied Physics has investigated the microstructures of CMMs by XPCI and they have established and developed a quantitative X-ray phase contrast micro-CT for investigating the characteristic microstructures of CMMs. During this period, a variety of typical CMMs have been investigated, from two-dimensional (2D) radiography to three-dimensional (3D) micro-CT, from qualitative to quantitative. Taken together, these results verify that quantitative X-ray phase contrast micro-CT is a practical tool for the microscopic investigation of CMMs. Additionally, further efforts are being made to find the relationship between the microstructures' quantitative factors and active chemical components. At present

  11. Single-step, quantitative x-ray differential phase contrast imaging using spectral detection in a coded aperture setup

    NASA Astrophysics Data System (ADS)

    Das, Mini; Liang, Zhihua

    2015-03-01

    In this abstract we describe the first non-interferometric x-ray phase contrast imaging (PCI) method that uses only a single-measurement step to retrieve with quantitative accuracy absorption, phase and differential phase. Our approach is based on utilizing spectral information from photon counting spectral detectors in conjunction with a coded aperture PCI setting to simplify the x-ray "phase problem" to a one-step method. The method by virtue of being single-step with no motion of any component for a given projection image has significantly high potential to overcome the barriers currently faced by PCI.

  12. Hemodynamic Measurement Using Four-Dimensional Phase-Contrast MRI: Quantification of Hemodynamic Parameters and Clinical Applications

    PubMed Central

    Ha, Hojin; Kim, Guk Bae; Kweon, Jihoon; Lee, Sang Joon; Kim, Young-Hak; Lee, Deok Hee

    2016-01-01

    Recent improvements have been made to the use of time-resolved, three-dimensional phase-contrast (PC) magnetic resonance imaging (MRI), which is also named four-dimensional (4D) PC-MRI or 4D flow MRI, in the investigation of spatial and temporal variations in hemodynamic features in cardiovascular blood flow. The present article reviews the principle and analytical procedures of 4D PC-MRI. Various fluid dynamic biomarkers for possible clinical usage are also described, including wall shear stress, turbulent kinetic energy, and relative pressure. Lastly, this article provides an overview of the clinical applications of 4D PC-MRI in various cardiovascular regions. PMID:27390537

  13. Development of Absolute Calibration of the Phase Contrast Imaging Diagnostic and Experimental Tests in Alcator C-Mod

    NASA Astrophysics Data System (ADS)

    Tsujii, N.; Porkolab, M.; Edlund, E. M.; Lin, L.

    2007-11-01

    The Phase Contrast Imaging (PCI) system in Alcator C-Mod is used to measure density perturbations from MHD modes, turbulence and RF waves. Recently, an absolutely calibrated system has been installed. This system consists of a set of transducers which cover frequency from 30 kHz to 200 kHz, and wavenumber from 5.5 cm-1 to 36.6 cm-1. The amplitude and phase of the transducer wavefronts are measured using a calibrated microphone. We will present the system design and modeling of this calibration system. Initial results, including a comparison with experimental measurements will also be discussed, if available.

  14. Phase contrast X-ray microtomography of the Rhodnius prolixus head: Comparison of direct reconstruction and phase retrieval approach

    NASA Astrophysics Data System (ADS)

    Almeida, A. P.; Braz, D.; Nogueira, L. P.; Colaço, M. V.; Soares, J.; Cardoso, S. C.; Garcia, E. S.; Azambuja, P.; Gonzalez, M. S.; Mohammadi, S.; Tromba, G.; Barroso, R. C.

    2014-02-01

    We have used phase-contrast X-ray microtomography (PPC-μCT) to study the head of the blood-feeding bug, Rhodnius prolixus, which is one of the most important insect vector of Trypanosoma cruzi, ethiologic agent of Chagas disease in Latin America. Images reconstructed from phase-retrieved projections processed by ANKA phase are compared to those obtained through direct tomographic reconstruction of the flat-field-corrected transmission radiographs. It should be noted that the relative locations of the important morphological internal structures are observable with a precision that is difficult to obtain without the phase retrieval approach.

  15. Ultrafast x-ray phase-contrast imaging of the initial coalescence phase of two water droplets.

    SciTech Connect

    Fezzaa, K.; Wang, Y.; X-Ray Science Division

    2008-03-14

    We report an ultrafast x-ray phase-contrast imaging study of the early merging dynamics of two water drops in air. Owing to the edge-enhancement capability, the high penetrability, and the unprecedented temporal and spatial resolutions offered by this new x-ray technique, the coalescence singularity of two water drops was revisited. A finite initial contact radius was identified and the evolvement of the trapped toroidal air bubble was studied for the first time. Despite the existence of this finite initial contact radius, the subsequent meniscus radius followed power laws which agree with theoretical predictions for the inviscid regime.

  16. Hemodynamic Measurement Using Four-Dimensional Phase-Contrast MRI: Quantification of Hemodynamic Parameters and Clinical Applications.

    PubMed

    Ha, Hojin; Kim, Guk Bae; Kweon, Jihoon; Lee, Sang Joon; Kim, Young-Hak; Lee, Deok Hee; Yang, Dong Hyun; Kim, Namkug

    2016-01-01

    Recent improvements have been made to the use of time-resolved, three-dimensional phase-contrast (PC) magnetic resonance imaging (MRI), which is also named four-dimensional (4D) PC-MRI or 4D flow MRI, in the investigation of spatial and temporal variations in hemodynamic features in cardiovascular blood flow. The present article reviews the principle and analytical procedures of 4D PC-MRI. Various fluid dynamic biomarkers for possible clinical usage are also described, including wall shear stress, turbulent kinetic energy, and relative pressure. Lastly, this article provides an overview of the clinical applications of 4D PC-MRI in various cardiovascular regions. PMID:27390537

  17. Iterative reconstruction algorithm for analyzer-based phase-contrast computed tomography of hard and soft tissue

    NASA Astrophysics Data System (ADS)

    Sunaguchi, Naoki; Yuasa, Tetsuya; Ando, Masami

    2013-09-01

    We propose a reconstruction algorithm for analyzer-based phase-contrast computed tomography (CT) applicable to biological samples including hard tissue that may generate conspicuous artifacts with the conventional reconstruction method. The algorithm is an iterative procedure that goes back and forth between a tomogram and its sinogram through the Radon transform and CT reconstruction, while imposing a priori information in individual regions. We demonstrate the efficacy of the algorithm using synthetic data generated by computer simulation reflecting actual experimental conditions and actual data acquired from a rat foot by a dark field imaging system.

  18. Abdominal Compartment Hypertension and Abdominal Compartment Syndrome.

    PubMed

    Maluso, Patrick; Olson, Jody; Sarani, Babak

    2016-04-01

    Intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) are rare but potentially morbid diagnoses. Clinical index of suspicion for these disorders should be raised following massive resuscitation, abdominal wall reconstruction/injury, and in those with space-occupying disorders in the abdomen. Gold standard for diagnosis involves measurement of bladder pressure, with a pressure greater than 12 mm Hg being consistent with IAH and greater than 25 mm Hg being consistent with ACS. Decompressive laparotomy is definitive therapy but paracentesis can be equally therapeutic in properly selected patients. Left untreated, ACS can lead to multisystem organ failure and death. PMID:27016163

  19. Abdominal Circulatory Interactions.

    PubMed

    Dagar, Gaurav; Taneja, Amit; Nanchal, Rahul S

    2016-04-01

    The abdominal compartment is separated from the thoracic compartment by the diaphragm. Under normal circumstances, a large portion of the venous return crosses the splanchnic and nonsplanchnic abdominal regions before entering the thorax and the right side of the heart. Mechanical ventilation may affect abdominal venous return independent of its interactions at the thoracic level. Changes in pressure in the intra-abdominal compartment may have important implications for organ function within the thorax, particularly if there is a sustained rise in intra-abdominal pressure. It is important to understand the consequences of abdominal pressure changes on respiratory and circulatory physiology. This article elucidates important abdominal-respiratory-circulatory interactions and their clinical effects. PMID:27016167

  20. Quantifying Morphological Parameters of the Terminal Branching Units in a Mouse Lung by Phase Contrast Synchrotron Radiation Computed Tomography

    PubMed Central

    Hwang, Jeongeun; Kim, Miju; Kim, Seunghwan; Lee, Jinwon

    2013-01-01

    An effective technique of phase contrast synchrotron radiation computed tomography was established for the quantitative analysis of the microstructures in the respiratory zone of a mouse lung. Heitzman’s method was adopted for the whole-lung sample preparation, and Canny’s edge detector was used for locating the air-tissue boundaries. This technique revealed detailed morphology of the respiratory zone components, including terminal bronchioles and alveolar sacs, with sufficiently high resolution of 1.74 µm isotropic voxel size. The technique enabled visual inspection of the respiratory zone components and comprehension of their relative positions in three dimensions. To check the method’s feasibility for quantitative imaging, morphological parameters such as diameter, surface area and volume were measured and analyzed for sixteen randomly selected terminal branching units, each consisting of a terminal bronchiole and a pair of succeeding alveolar sacs. The four types of asymmetry ratios concerning alveolar sac mouth diameter, alveolar sac surface area, and alveolar sac volume are measured. This is the first ever finding of the asymmetry ratio for the terminal bronchioles and alveolar sacs, and it is noteworthy that an appreciable degree of branching asymmetry was observed among the alveolar sacs at the terminal end of the airway tree, despite the number of samples was small yet. The series of efficient techniques developed and confirmed in this study, from sample preparation to quantification, is expected to contribute to a wider and exacter application of phase contrast synchrotron radiation computed tomography to a variety of studies. PMID:23704918

  1. In Vitro Validation of an Artefact Suppression Algorithm in X-Ray Phase-Contrast Computed Tomography.

    PubMed

    Sunaguchi, Naoki; Yuasa, Tetsuya; Hirano, Shin-Ichi; Gupta, Rajiv; Ando, Masami

    2015-01-01

    X-ray phase-contrast tomography can significantly increase the contrast-resolution of conventional attenuation-contrast imaging, especially for soft-tissue structures that have very similar attenuation. Just as in attenuation-based tomography, phase contrast tomography requires a linear dependence of aggregate beam direction on the incremental direction alteration caused by individual voxels along the path of the X-ray beam. Dense objects such as calcifications in biological specimens violate this condition. There are extensive beam deflection artefacts in the vicinity of such structures because they result in large distortion of wave front due to the large difference of refractive index; for such large changes in beam direction, the transmittance of the silicon analyzer crystal saturates and is no longer linearly dependent on the angle of refraction. This paper describes a method by which these effects can be overcome and excellent soft-tissue contrast of phase tomography can be preserved in the vicinity of such artefact-producing structures. PMID:26295713

  2. In Vitro Validation of an Artefact Suppression Algorithm in X-Ray Phase-Contrast Computed Tomography

    PubMed Central

    Sunaguchi, Naoki; Yuasa, Tetsuya; Hirano, Shin-ichi; Gupta, Rajiv; Ando, Masami

    2015-01-01

    X-ray phase-contrast tomography can significantly increase the contrast-resolution of conventional attenuation-contrast imaging, especially for soft-tissue structures that have very similar attenuation. Just as in attenuation-based tomography, phase contrast tomography requires a linear dependence of aggregate beam direction on the incremental direction alteration caused by individual voxels along the path of the X-ray beam. Dense objects such as calcifications in biological specimens violate this condition. There are extensive beam deflection artefacts in the vicinity of such structures because they result in large distortion of wave front due to the large difference of refractive index; for such large changes in beam direction, the transmittance of the silicon analyzer crystal saturates and is no longer linearly dependent on the angle of refraction. This paper describes a method by which these effects can be overcome and excellent soft-tissue contrast of phase tomography can be preserved in the vicinity of such artefact-producing structures. PMID:26295713

  3. Efficient phase contrast imaging in STEM using a pixelated detector. Part 1: Experimental demonstration at atomic resolution

    SciTech Connect

    Pennycook, Timothy J.; Lupini, Andrew R.; Yang, Hao; Murfitt, Matthew F.; Jones, Lewys; Nellist, Peter D.

    2014-10-15

    In this paper, we demonstrate a method to achieve high efficiency phase contrast imaging in aberration corrected scanning transmission electron microscopy (STEM) with a pixelated detector. The pixelated detector is used to record the Ronchigram as a function of probe position which is then analyzed with ptychography. Ptychography has previously been used to provide super-resolution beyond the diffraction limit of the optics, alongside numerically correcting for spherical aberration. Here we rely on a hardware aberration corrector to eliminate aberrations, but use the pixelated detector data set to utilize the largest possible volume of Fourier space to create high efficiency phase contrast images. The use of ptychography to diagnose the effects of chromatic aberration is also demonstrated. In conclusion, the four dimensional dataset is used to compare different bright field detector configurations from the same scan for a sample of bilayer graphene. Our method of high efficiency ptychography produces the clearest images, while annular bright field produces almost no contrast for an in-focus aberration-corrected probe.

  4. X-ray phase-contrast CO2 angiography for sub-10 μm vessel imaging

    NASA Astrophysics Data System (ADS)

    Lundström, U.; Larsson, D. H.; Burvall, A.; Scott, L.; Westermark, U. K.; Wilhelm, M.; Arsenian Henriksson, M.; Hertz, H. M.

    2012-11-01

    X-ray in-line phase contrast has recently been combined with CO2 angiography for high-resolution small-animal vascular imaging at low radiation dose. In this paper we further investigate the potential and limitations of this method and demonstrate observation of vessels down to 8 μm in diameter, considerably smaller than the 60 μm previously reported. Our in-line phase-contrast imaging system is based on a liquid-metal-jet-anode x-ray source and utilizes free-space propagation to convert phase shifts, caused by refractive index variations, into intensity differences. Enhanced refractive index variations are obtained through injection of CO2 gas into the vascular system to replace the blood. We show rat-kidney images with blood vessels down to 27 μm in diameter and mouse-ear images with vessels down to 8 μm. The minimum size of observable blood vessels is found to be limited by the penetration of gas into the vascular system and the signal-to-noise ratio, i.e. the allowed dose. The diameters of vessels being gas-filled depend on the gas pressure and follow a simple model based on surface tension. A theoretical signal-to-noise comparison shows that this method requires 1000 times less radiation dose than conventional iodine-based absorption contrast for observing sub-50 μm vessels.

  5. Clinical application of low-dose phase contrast breast CT: methods for the optimization of the reconstruction workflow

    PubMed Central

    Pacilè, S.; Brun, F.; Dullin, C.; Nesterest, Y. I.; Dreossi, D.; Mohammadi, S.; Tonutti, M.; Stacul, F.; Lockie, D.; Zanconati, F.; Accardo, A.; Tromba, G.; Gureyev, T. E.

    2015-01-01

    Results are presented of a feasibility study of three-dimensional X-ray tomographic mammography utilising in-line phase contrast. Experiments were performed at SYRMEP beamline of Elettra synchrotron. A specially designed plastic phantom and a mastectomy sample containing a malignant lesion were used to study the reconstructed image quality as a function of different image processing operations. Detailed evaluation and optimization of image reconstruction workflows have been carried out using combinations of several advanced computed tomography algorithms with different pre-processing and post-processing steps. Special attention was paid to the effect of phase retrieval on the diagnostic value of the reconstructed images. A number of objective image quality indices have been applied for quantitative evaluation of the results, and these were compared with subjective assessments of the same images by three experienced radiologists and one pathologist. The outcomes of this study provide practical guidelines for the optimization of image processing workflows in synchrotron-based phase-contrast mammo-tomography. PMID:26309770

  6. An efficient reconstruction algorithm for differential phase-contrast tomographic images from a limited number of views

    SciTech Connect

    Sunaguchi, Naoki; Yuasa, Tetsuya; Gupta, Rajiv; Ando, Masami

    2015-12-21

    The main focus of this paper is reconstruction of tomographic phase-contrast image from a set of projections. We propose an efficient reconstruction algorithm for differential phase-contrast computed tomography that can considerably reduce the number of projections required for reconstruction. The key result underlying this research is a projection theorem that states that the second derivative of the projection set is linearly related to the Laplacian of the tomographic image. The proposed algorithm first reconstructs the Laplacian image of the phase-shift distribution from the second-derivative of the projections using total variation regularization. The second step is to obtain the phase-shift distribution by solving a Poisson equation whose source is the Laplacian image previously reconstructed under the Dirichlet condition. We demonstrate the efficacy of this algorithm using both synthetically generated simulation data and projection data acquired experimentally at a synchrotron. The experimental phase data were acquired from a human coronary artery specimen using dark-field-imaging optics pioneered by our group. Our results demonstrate that the proposed algorithm can reduce the number of projections to approximately 33% as compared with the conventional filtered backprojection method, without any detrimental effect on the image quality.

  7. Synchrotron Radiation X-Ray Phase-Contrast Tomography Visualizes Microvasculature Changes in Mice Brains after Ischemic Injury

    PubMed Central

    Ji, Yuanyuan; Xie, Bohua; Lin, Xiaojie

    2016-01-01

    Imaging brain microvasculature is important in plasticity studies of cerebrovascular diseases. Applying contrast agents, traditional μCT and μMRI methods gain imaging contrast for vasculature. The aim of this study is to develop a synchrotron radiation X-ray inline phase-contrast tomography (SRXPCT) method for imaging the intact mouse brain (micro)vasculature in high resolution (~3.7 μm) without contrast agent. A specific preparation protocol was proposed to enhance the phase contrast of brain vasculature by using density difference over gas-tissue interface. The CT imaging system was developed and optimized to obtain 3D brain vasculature of adult male C57BL/6 mice. The SRXPCT method was further applied to investigate the microvasculature changes in mouse brains (n = 14) after 14-day reperfusion from transient middle cerebral artery occlusion (tMCAO). 3D reconstructions of brain microvasculature demonstrated that the branching radius ratio (post- to preinjury) of small vessels (radius < 7.4 μm) in the injury group was significantly smaller than that in the sham group (p < 0.05). This result revealed the active angiogenesis in the recovery brain after stroke. As a high-resolution and contrast-agent-free method, the SRXPCT method demonstrates higher potential in investigations of functional plasticity in cerebrovascular diseases. PMID:27563468

  8. The dynamic response of high pressure phase of Si using phase contrast imaging and X-ray diffraction

    NASA Astrophysics Data System (ADS)

    Lee, H. J.; Galtier, E.; Xing, Z.; Gleason, A.; Granados, E.; Tavella, F.; Schropp, A.; Seiboth, F.; Schroer, C.; Higginbotham, A.; Brown, S.; Arnold, B.; Curiel, R.; Peterswright, D.; Fry, A.; Nagler, B.

    2015-11-01

    Static compression studies have revealed that crystalline silicon undergoes phase transitions from a cubic diamond structure to a variety of phases including body-centered tetragonal phase, an orthorhombic phase, and a hexagonal primitive phase. However, the dynamic response of silicon at high pressure is not well understood. Phase contrast imaging has proven to be a powerful tool for probing density changes caused by the shock propagation into a material. With respect to the elastic and plastic compression, we image shock waves in Si with high spatial resolution using the LCLS X-ray free electron laser and Matter in Extreme Conditions instrument. In this study, the long pulse optical laser with pseudoflat top shape creates high pressures up to 60 GPa. We also measure the crystal structure by observing the X-ray diffraction orthogonal to the shock propagation direction over a range of pressure. In this talk, we will present the capability of simultaneously performing phase contrast imaging and in situ X-ray diffraction during shock loading and will discuss the dynamic response of Si in high pressure phases

  9. Alignment of low-dose X-ray fluorescence tomography images using differential phase contrast

    PubMed Central

    Hong, Young Pyo; Gleber, Sophie-Charlotte; O’Halloran, Thomas V.; Que, Emily L.; Bleher, Reiner; Vogt, Stefan; Woodruff, Teresa K.; Jacobsen, Chris

    2014-01-01

    X-ray fluorescence nanotomography provides unprecedented sensitivity for studies of trace metal distributions in whole biological cells. Dose fractionation, in which one acquires very low dose individual projections and then obtains high statistics reconstructions as signal from a voxel is brought together (Hegerl & Hoppe, 1976 ▶), requires accurate alignment of these individual projections so as to correct for rotation stage runout. It is shown here that differential phase contrast at 10.2 keV beam energy offers the potential for accurate cross-correlation alignment of successive projections, by demonstrating that successive low dose, 3 ms per pixel, images acquired at the same specimen position and rotation angle have a narrower and smoother cross-correlation function (1.5 pixels FWHM at 300 nm pixel size) than that obtained from zinc fluorescence images (25 pixels FWHM). The differential phase contrast alignment resolution is thus well below the 700 nm × 500 nm beam spot size used in this demonstration, so that dose fractionation should be possible for reduced-dose, more rapidly acquired, fluorescence nanotomography experiments. PMID:24365941

  10. Visualization of microvasculature by x-ray in-line phase contrast imaging in rat spinal cord

    NASA Astrophysics Data System (ADS)

    Hu, Jian-Zhong; Wu, Tian-Ding; Zeng, Lei; Liu, Hui-Qiang; He, You; Du, Guo-Hao; Lu, Hong-Bin

    2012-03-01

    Computed tomography combined with angiography has recently been developed to visualize three-dimensional (3D) vascular structure in experi-mental and clinical studies. However, there remain difficulties in using conventional x-ray angiography to detect small vessels with a diameter less than 200 µm. This study attempted to develop a novel method for visualizing the micro-angioarchitecture of rat spinal cord. Herein, synchrotron radiation-based x-ray in-line phase contrast computed tomography (IL-XPCT) was used to obtain 3D micro-vessel structure without angiography. The digital phase contrast images were compared with conventional histological sections. Our results clearly demonstrated that the resolution limit of the spatial blood supply network in the normal rat thoracic cord appeared to be as small as ∼10 µm. The rendered images were consistent with that obtained from histo-morphology sections. In summary, IL-XPCT is a potential tool to investigate the 3D neurovascular morphology of the rat spinal cord without the use of contrast agents, and it could help to evaluate the validity of the pro- or anti-angiogenesis therapeutic strategies on microvasculature repair or regeneration.

  11. Asymmetric rotational axis reconstruction of grating-based x-ray phase contrast tomography of the human cerebellum

    NASA Astrophysics Data System (ADS)

    Schulz, Georg; Weitkamp, Timm; Zanette, Irene; Pfeiffer, Franz; Müller-Gerbl, Magdalena; David, Christian; Müller, Bert

    2012-10-01

    The brain has an outstanding functional importance in the human organism. Therefore, there is a strong need for three-dimensional brain imaging modalities. Magnetic resonance imaging provides deep insights but its spatial resolution is insufficient to study the structure on the cellular level. X-ray absorption microtomography yields the necessary spatial resolution, but shows only marginal contrast between the different types of brain tissue. Alternatively, differential X-ray phase contrast obtained with grating interferometry, which is known for much better differentiations between soft tissues can be used for the visualization of the human brain. As important structures of the human brain such as the human thalamus have dimensions of several centimeters, a large field of view is required. In the present communication, we report an evaluation of grating-based X-ray phase contrast microtomography in the off-axis modus which allows to expand the field of view up to a factor of two but may reduce the image quality. We demonstrate that tomograms with comparable contrast-to-noise values, about 10%, and 50% inferior spatial resolution can be generated with off-axis measurements. As one can reduce the effective pixel size up to a factor of two, the choice of an asymmetrical rotation axis can give rise to an improvement of the spatial resolution by 20%.

  12. A compressed sensing based reconstruction algorithm for synchrotron source propagation-based X-ray phase contrast computed tomography

    NASA Astrophysics Data System (ADS)

    Melli, Seyed Ali; Wahid, Khan A.; Babyn, Paul; Montgomery, James; Snead, Elisabeth; El-Gayed, Ali; Pettitt, Murray; Wolkowski, Bailey; Wesolowski, Michal

    2016-01-01

    Synchrotron source propagation-based X-ray phase contrast computed tomography is increasingly used in pre-clinical imaging. However, it typically requires a large number of projections, and subsequently a large radiation dose, to produce high quality images. To improve the applicability of this imaging technique, reconstruction algorithms that can reduce the radiation dose and acquisition time without degrading image quality are needed. The proposed research focused on using a novel combination of Douglas-Rachford splitting and randomized Kaczmarz algorithms to solve large-scale total variation based optimization in a compressed sensing framework to reconstruct 2D images from a reduced number of projections. Visual assessment and quantitative performance evaluations of a synthetic abdomen phantom and real reconstructed image of an ex-vivo slice of canine prostate tissue demonstrate that the proposed algorithm is competitive in reconstruction process compared with other well-known algorithms. An additional potential benefit of reducing the number of projections would be reduction of time for motion artifact to occur if the sample moves during image acquisition. Use of this reconstruction algorithm to reduce the required number of projections in synchrotron source propagation-based X-ray phase contrast computed tomography is an effective form of dose reduction that may pave the way for imaging of in-vivo samples.

  13. 2D grating simulation for X-ray phase-contrast and dark-field imaging with a Talbot interferometer

    NASA Astrophysics Data System (ADS)

    Zanette, Irene; David, Christian; Rutishauser, Simon; Weitkamp, Timm

    2010-04-01

    Talbot interferometry is a recently developed and an extremely powerful X-ray phase-contrast imaging technique. Besides giving access to ultra-high sensitivity differential phase contrast images, it also provides the dark field image, which is a map of the scattering power of the sample. In this paper we investigate the potentialities of an improved version of the interferometer, in which two dimensional gratings are used instead of standard line grids. This approach allows to overcome the difficulties that might be encountered in the images produced by a one dimensional interferometer. Among these limitations there are the phase wrapping and quantitative phase retrieval problems and the directionality of the differential phase and dark-field signals. The feasibility of the 2D Talbot interferometer has been studied with a numerical simulation on the performances of its optical components under different circumstances. The gratings can be obtained either by an ad hoc fabrication of the 2D structures or by a superposition of two perpendicular linear grids. Through this simulation it has been possible to find the best parameters for a practical implementation of the 2D Talbot interferometer.

  14. Clinical application of low-dose phase contrast breast CT: methods for the optimization of the reconstruction workflow.

    PubMed

    Pacilè, S; Brun, F; Dullin, C; Nesterest, Y I; Dreossi, D; Mohammadi, S; Tonutti, M; Stacul, F; Lockie, D; Zanconati, F; Accardo, A; Tromba, G; Gureyev, T E

    2015-08-01

    Results are presented of a feasibility study of three-dimensional X-ray tomographic mammography utilising in-line phase contrast. Experiments were performed at SYRMEP beamline of Elettra synchrotron. A specially designed plastic phantom and a mastectomy sample containing a malignant lesion were used to study the reconstructed image quality as a function of different image processing operations. Detailed evaluation and optimization of image reconstruction workflows have been carried out using combinations of several advanced computed tomography algorithms with different pre-processing and post-processing steps. Special attention was paid to the effect of phase retrieval on the diagnostic value of the reconstructed images. A number of objective image quality indices have been applied for quantitative evaluation of the results, and these were compared with subjective assessments of the same images by three experienced radiologists and one pathologist. The outcomes of this study provide practical guidelines for the optimization of image processing workflows in synchrotron-based phase-contrast mammo-tomography. PMID:26309770

  15. Alignment of low-dose X-ray fluorescence tomography images using differential phase contrast.

    PubMed

    Hong, Young Pyo; Gleber, Sophie-Charlotte; O'Halloran, Thomas V; Que, Emily L; Bleher, Reiner; Vogt, Stefan; Woodruff, Teresa K; Jacobsen, Chris

    2014-01-01

    X-ray fluorescence nanotomography provides unprecedented sensitivity for studies of trace metal distributions in whole biological cells. Dose fractionation, in which one acquires very low dose individual projections and then obtains high statistics reconstructions as signal from a voxel is brought together (Hegerl & Hoppe, 1976), requires accurate alignment of these individual projections so as to correct for rotation stage runout. It is shown here that differential phase contrast at 10.2 keV beam energy offers the potential for accurate cross-correlation alignment of successive projections, by demonstrating that successive low dose, 3 ms per pixel, images acquired at the same specimen position and rotation angle have a narrower and smoother cross-correlation function (1.5 pixels FWHM at 300 nm pixel size) than that obtained from zinc fluorescence images (25 pixels FWHM). The differential phase contrast alignment resolution is thus well below the 700 nm × 500 nm beam spot size used in this demonstration, so that dose fractionation should be possible for reduced-dose, more rapidly acquired, fluorescence nanotomography experiments. PMID:24365941

  16. A feasibility study of X-ray phase-contrast mammographic tomography at the Imaging and Medical beamline of the Australian Synchrotron.

    PubMed

    Nesterets, Yakov I; Gureyev, Timur E; Mayo, Sheridan C; Stevenson, Andrew W; Thompson, Darren; Brown, Jeremy M C; Kitchen, Marcus J; Pavlov, Konstantin M; Lockie, Darren; Brun, Francesco; Tromba, Giuliana

    2015-11-01

    Results are presented of a recent experiment at the Imaging and Medical beamline of the Australian Synchrotron intended to contribute to the implementation of low-dose high-sensitivity three-dimensional mammographic phase-contrast imaging, initially at synchrotrons and subsequently in hospitals and medical imaging clinics. The effect of such imaging parameters as X-ray energy, source size, detector resolution, sample-to-detector distance, scanning and data processing strategies in the case of propagation-based phase-contrast computed tomography (CT) have been tested, quantified, evaluated and optimized using a plastic phantom simulating relevant breast-tissue characteristics. Analysis of the data collected using a Hamamatsu CMOS Flat Panel Sensor, with a pixel size of 100 µm, revealed the presence of propagation-based phase contrast and demonstrated significant improvement of the quality of phase-contrast CT imaging compared with conventional (absorption-based) CT, at medically acceptable radiation doses. PMID:26524316

  17. External respiratory motion for abdominal radiotherapy patients: implications for patient alignment

    SciTech Connect

    Kearvell, Rachel; Ebert, Martin A

    2003-12-31

    Conformal external beam radiotherapy relies on accurate spatial positioning of the tumor and normal tissues during treatment. For abdominal patients, this is complicated by the motion of internal organs and the external patient contour due to respiration. As external motion influences the degree of accuracy achievable in patient setup, this motion was studied to provide indication of motions occurring during treatment, as well as to assess the technique of breath-holding at exhale (B-HEX). The motion of external abdominal points (anterior and right lateral) of a series of volunteers was tracked in real-time using an infrared tracking system, with the volunteers in treatment position. The resulting motion data was assessed to evaluate (1) the change in position of each point per breath/breath-hold, (2) the change in position between breaths/breath-holds, and (3) the change in position across the whole recording time. Analysis shows that, for the anterior abdominal point, there is little difference in the variation of position with time for free-breathing as opposed to the B-HEX technique. For the lateral point however, the B-HEX technique reduces the motion during each treatment cycle (i.e., during the breath-hold) and over an extended period (i.e., during a series of breath-holds). The B-HEX technique thus provides greater accuracy for setup to lateral markers and provides the opportunity to reduce systematic and random localization errors.

  18. Abdominal CT scan

    MedlinePlus

    ... tumors, including cancer Infections or injury Kidney stones Appendicitis ... also be due to: Abdominal aortic aneurysm Abscesses Appendicitis Bowel wall thickening Retroperitoneal fibrosis Renal artery stenosis ...

  19. System for phase-contrast x-ray radiography using X pinch radiation and a method thereof

    DOEpatents

    Chandler, Katherine; Chelkovenko, Tatiana; Hammer, David; Pikuz, Sergei; Sinars, Daniel; Song, Byungmoo

    2007-11-06

    A radiograph system with an anode plate, a cathode plate, and a power source coupled to said anode plate and the cathode plate. At least two wires coupled between the anode plate and the cathode plate provide a configuration to form an X-pinch having a photon source size of less than five microns at energies above 2.5 keV. Material at the configuration forming the X-pinch vaporizes upon application of a suitable current to the wires forming a dense hot plasma and emitting a single x-ray pulse with sufficient photons having energies in the range of from about 2.5 keV to about 20 keV to provide a phase contrast image of an object in the path of the photons. Multiple simultaneous images may be formed of a plurality of objects. Suitable filters and x-ray detectors are provided.

  20. Rapid, High-Throughput Tracking of Bacterial Motility in 3D via Phase-Contrast Holographic Video Microscopy

    PubMed Central

    Cheong, Fook Chiong; Wong, Chui Ching; Gao, YunFeng; Nai, Mui Hoon; Cui, Yidan; Park, Sungsu; Kenney, Linda J.; Lim, Chwee Teck

    2015-01-01

    Tracking fast-swimming bacteria in three dimensions can be extremely challenging with current optical techniques and a microscopic approach that can rapidly acquire volumetric information is required. Here, we introduce phase-contrast holographic video microscopy as a solution for the simultaneous tracking of multiple fast moving cells in three dimensions. This technique uses interference patterns formed between the scattered and the incident field to infer the three-dimensional (3D) position and size of bacteria. Using this optical approach, motility dynamics of multiple bacteria in three dimensions, such as speed and turn angles, can be obtained within minutes. We demonstrated the feasibility of this method by effectively tracking multiple bacteria species, including Escherichia coli, Agrobacterium tumefaciens, and Pseudomonas aeruginosa. In addition, we combined our fast 3D imaging technique with a microfluidic device to present an example of a drug/chemical assay to study effects on bacterial motility. PMID:25762336