Science.gov

Sample records for advanced flat panel

  1. Technical advances of interventional fluoroscopy and flat panel image receptor.

    PubMed

    Lin, Pei-Jan Paul

    2008-11-01

    In the past decade, various radiation reducing devices and control circuits have been implemented on fluoroscopic imaging equipment. Because of the potential for lengthy fluoroscopic procedures in interventional cardiovascular angiography, these devices and control circuits have been developed for the cardiac catheterization laboratories and interventional angiography suites. Additionally, fluoroscopic systems equipped with image intensifiers have benefited from technological advances in x-ray tube, x-ray generator, and spectral shaping filter technologies. The high heat capacity x-ray tube, the medium frequency inverter generator with high performance switching capability, and the patient dose reduction spectral shaping filter had already been implemented on the image intensified fluoroscopy systems. These three underlying technologies together with the automatic dose rate and image quality (ADRIQ) control logic allow patients undergoing cardiovascular angiography procedures to benefit from "lower patient dose" with "high image quality." While photoconductor (or phosphor plate) x-ray detectors and signal capture thin film transistor (TFT) and charge coupled device (CCD) arrays are analog in nature, the advent of the flat panel image receptor allowed for fluoroscopy procedures to become more streamlined. With the analog-to-digital converter built into the data lines, the flat panel image receptor appears to become a digital device. While the transition from image intensified fluoroscopy systems to flat panel image receptor fluoroscopy systems is part of the on-going "digitization of imaging," the value of a flat panel image receptor may have to be evaluated with respect to patient dose, image quality, and clinical application capabilities. The advantage of flat panel image receptors has yet to be fully explored. For instance, the flat panel image receptor has its disadvantages as compared to the image intensifiers; the cost of the equipment is probably the most

  2. Stereoscopic Flat Panel Display

    DTIC Science & Technology

    2004-12-01

    the display of stereo imagery have been demonstrated. Stereoscopic displays typically require the user to wear special headgear. Autostereoscopic ...components and the resulting changes in the encoding algorithm. Keywords: Stereoscopic display, LCD, 3D , polarization encoding, flat panel 1...panel display when viewing non-stereoscopic imagery or data. Remotely operated vehicles do not represent the only potential application for 3D

  3. Microgap flat panel display

    DOEpatents

    Wuest, Craig R.

    1998-01-01

    A microgap flat panel display which includes a thin gas-filled display tube that utilizes switched X-Y "pixel" strips to trigger electron avalanches and activate a phosphor at a given location on a display screen. The panel utilizes the principal of electron multiplication in a gas subjected to a high electric field to provide sufficient electron current to activate standard luminescent phosphors located on an anode. The X-Y conductive strips of a few micron widths may for example, be deposited on opposite sides of a thin insulating substrate, or on one side of the adjacent substrates and function as a cathode. The X-Y strips are separated from the anode by a gap filled with a suitable gas. Electrical bias is selectively switched onto X and Y strips to activate a "pixel" in the region where these strips overlap. A small amount of a long-lived radioisotope is used to initiate an electron avalanche in the overlap region when bias is applied. The avalanche travels through the gas filled gap and activates a luminescent phosphor of a selected color. The bias is adjusted to give a proportional electron multiplication to control brightness for given pixel.

  4. Microgap flat panel display

    DOEpatents

    Wuest, C.R.

    1998-12-08

    A microgap flat panel display is disclosed which includes a thin gas-filled display tube that utilizes switched X-Y ``pixel`` strips to trigger electron avalanches and activate a phosphor at a given location on a display screen. The panel utilizes the principal of electron multiplication in a gas subjected to a high electric field to provide sufficient electron current to activate standard luminescent phosphors located on an anode. The X-Y conductive strips of a few micron widths may for example, be deposited on opposite sides of a thin insulating substrate, or on one side of the adjacent substrates and function as a cathode. The X-Y strips are separated from the anode by a gap filled with a suitable gas. Electrical bias is selectively switched onto X and Y strips to activate a ``pixel`` in the region where these strips overlap. A small amount of a long-lived radioisotope is used to initiate an electron avalanche in the overlap region when bias is applied. The avalanche travels through the gas filled gap and activates a luminescent phosphor of a selected color. The bias is adjusted to give a proportional electron multiplication to control brightness for given pixel. 6 figs.

  5. Performance of advanced a-Si/CsI-based flat-panel x-ray detectors for mammography

    NASA Astrophysics Data System (ADS)

    Albagli, Douglas; Hudspeth, Heather; Possin, George E.; Lee, Ji Ung; Granfors, Paul R.; Giambattista, Brian W.

    2003-06-01

    The GE Senographe 2000D, the first full field digital mammography system based on amorphous Silicon (a-Si) flat panel arrays and a Cesium-Iodide (CsI) scintillator, has been in clinical use for several years. The purpose of this paper is to demonstrate and quantify improvements in the detective quantum efficiency (DQE) for both typical screening and ultra-low exposure levels for this technology platform. A new figure of merit, the electronic noise factor, is introduced to explicitly quantify the influence of the electronic noise, conversion factor, modulation transfer function (MTF), and pixel pitch towards the reduction of DQE at low exposure levels. Methods to improve the DQE through an optimization of both the flat panel design and the scintillator deposition process are discussed. The results show a substantial improvement in the DQE(f) at all frequencies and demonstrate the potential for DQE(0) to exceed 80%. The combination of high DQE at ultra low exposures and the inherent fast read-out capability makes this technology platform ideal for both current clinical procedures and advanced applications that may use multiple projections (tomosynthesis) or contrast media to enhance digital mammography.

  6. Flat panel displays in an underwater cockpit

    NASA Astrophysics Data System (ADS)

    Sola, Kenneth E.

    1999-08-01

    This paper reports on a highly unusual application of flat panel displays in a cockpit. The cockpit is found in a mini- submarine of the Advanced SEAL Delivery System (ASDS), a state-of-the-art military platform designed to deliver U.S. Navy SEALs, and other special forces, to their mission locations. For security reasons, the presentation details are intentionally kept minimal.

  7. Flat panel planar optic display

    SciTech Connect

    Veligdan, J.T.

    1994-11-01

    A prototype 10 inch flat panel Planar Optic Display, (POD), screen has been constructed and tested. This display screen is comprised of hundreds of planar optic class sheets bonded together with a cladding layer between each sheet where each glass sheet represents a vertical line of resolution. The display is 9 inches wide by 5 inches high and approximately 1 inch thick. A 3 milliwatt HeNe laser is used as the illumination source and a vector scanning technique is employed.

  8. Flat panel display Impurity doping technology for flat panel displays

    NASA Astrophysics Data System (ADS)

    Suzuki, Toshiharu

    2005-08-01

    Features of the flat panel displays (FPDs) such as liquid crystal display (LCD) and organic light emitting diode (OLED) display, etc. using low temperature poly-Si (LTPS) thin film transistors (TFTs) are briefly reviewed comparing with other FPDs. The requirements for fabricating TFTs used for high performance FPDs and system on glass (SoG) are addressed. This paper focuses on the impurity doping technology, which is one of the key technologies together with crystallization by laser annealing, formation of high quality gate insulator and gate-insulator/poly-Si interface. The issues to be solved in impurity doping technology for state of the art and future TFTs are clarified.

  9. Laser illuminated flat panel display

    SciTech Connect

    Veligdan, J.T.

    1995-12-31

    A 10 inch laser illuminated flat panel Planar Optic Display (POD) screen has been constructed and tested. This POD screen technology is an entirely new concept in display technology. Although the initial display is flat and made of glass, this technology lends itself to applications where a plastic display might be wrapped around the viewer. The display screen is comprised of hundreds of planar optical waveguides where each glass waveguide represents a vertical line of resolution. A black cladding layer, having a lower index of refraction, is placed between each waveguide layer. Since the cladding makes the screen surface black, the contrast is high. The prototype display is 9 inches wide by 5 inches high and approximately I inch thick. A 3 milliwatt HeNe laser is used as the illumination source and a vector scanning technique is employed.

  10. [Canon's flat-panel detector].

    PubMed

    Matsumoto, Masao; Sumida, Iori; Ideguchi, Tadamitsu; Kawaji, Yasuyuki; Himuro, Kazuhiko

    2002-01-01

    We measured and evaluated digital, pre-sampling and overall imaging properties (characteristic curve, modulation transfer function (MTF), Wiener spectrum (WS), noise equivalent quanta (NEQ) ) for Cannon's flat-panel detector (FPD), Fuji computed radiography (FCR) and screen-film (S/F) systems, respectively. First, the digital and overall characteristic curves of FPD and FCR systems were more wide dynamic range than that of the S/F system. Second, the pre-sampling and overall MTF of FPD system were better than those of FCR system a little at lower spatial frequencies than 0.8 mm(-1), but the overall MTF of FPD and FCR systems were worse than that of S/F system a little at all spatial frequencies. Third, the digital and overall WS of FPD system were similar or better than those of FCR system, but the overall WS of FPD and FCR systems were worse than that of S/F system. Fourth, the pre-sampling and overall NEQ of FPD system were better than those of FCR system a little at lower spatial frequencies than 1.6 mm(-1), but the overall NEQ of FPD and FCR systems were worse than that of S/F system at all spatial frequencies. Comparison of chest phantom images showed that the FPD produced images with quality comparable to or higher than those of the FCR system. From these results, we can expect that the FPD is useful machine by using digital image processing and so on in the radiology department.

  11. [Hologic's Flat-Panel Detector].

    PubMed

    Ogata, Yuji; Matsumoto, Masao; Suekane, Koji

    2002-01-01

    We measured and evaluated digital, pre-sampling and overall imaging properties (characteristic curve, Modulation Transfer Function (MTF), Wiener spectrum (WS), Noise Equivalent Quanta (NEQ) and Detective Quantum Efficiency (DQE)) for Hologic's direct type and Cannon's indirect type of Flat-Panel Detector (FPD). First, the digital and overall characteristic curves of both types of FPD were more wide dynamic range than that of the S/F system. Second, the pre-sampling and overall MTF of the direct-type FPD system were superior to those of the indirect-type FPD system. Third, for identical exposures, the digital and overall WS of the direct-type FPD system were similar or worse than those of the indirect-type FPD system, and for larger exposure, the digital WS of the both types of FPD system were smaller, but the overall WS of the both types of FPD systems were larger. Fourth, the digital and overall NEQ and DQE of the direct-type FPD system were worse than those of the indirect-type FPD system at lower spatial frequencies than 1.75 - 2.0 mm(-1), but were worse at higher spatial frequencies than 1.75 - 2.0 mm(-1). We show radiographs made with the direct type of FPD system. Radiographs of square wave chart show the difference in MTF and contrast of the both types of FPD systems. As the result of evaluation of radiographs of chest phantom in point of noise by radiologists and radiological technologists, the direct type of FPD system needed double or more exposure dose than own standard condition, this dose was same as the indirect-type FPD system. And radiologists evaluated radiographs of human body, spatial resolution was very good, but contrast was much more likely to high at standard parameter. Therefore we have to consider exposure condition and image processing for the direct type of FPD system.

  12. Flat panel ferroelectric electron emission display system

    DOEpatents

    Sampayan, Stephen E.; Orvis, William J.; Caporaso, George J.; Wieskamp, Ted F.

    1996-01-01

    A device which can produce a bright, raster scanned or non-raster scanned image from a flat panel. Unlike many flat panel technologies, this device does not require ambient light or auxiliary illumination for viewing the image. Rather, this device relies on electrons emitted from a ferroelectric emitter impinging on a phosphor. This device takes advantage of a new electron emitter technology which emits electrons with significant kinetic energy and beam current density.

  13. Flat panel ferroelectric electron emission display system

    DOEpatents

    Sampayan, S.E.; Orvis, W.J.; Caporaso, G.J.; Wieskamp, T.F.

    1996-04-16

    A device is disclosed which can produce a bright, raster scanned or non-raster scanned image from a flat panel. Unlike many flat panel technologies, this device does not require ambient light or auxiliary illumination for viewing the image. Rather, this device relies on electrons emitted from a ferroelectric emitter impinging on a phosphor. This device takes advantage of a new electron emitter technology which emits electrons with significant kinetic energy and beam current density. 6 figs.

  14. Phosphors for flat panel emissive displays

    SciTech Connect

    Anderson, M.T.; Walko, R.J.; Phillips, M.L.F.

    1995-07-01

    An overview of emissive display technologies is presented. Display types briefly described include: cathode ray tubes (CRTs), field emission displays (FEDs), electroluminescent displays (ELDs), and plasma display panels (PDPs). The critical role of phosphors in further development of the latter three flat panel emissive display technologies is outlined. The need for stable, efficient red, green, and blue phosphors for RGB fall color displays is emphasized.

  15. [Present state and future of flat panel detector in Japan].

    PubMed

    Higashida, Yoshiharu

    2002-01-01

    In our country, the introduction of flat panel detector is carried out in the diagnosis region since before several years. In flat panel detector with the high image characteristic, large expectation is being placed. In this paper, image characteristic of flat panel detector and effectiveness of clinical application were reviewed. It is anticipated that flat panel detector with the excellent image characteristic gives large effect in the radiological diagnosis.

  16. Color Flat Panel Displays: 3D Autostereoscopic Brassboard and Field Sequential Illumination Technology.

    DTIC Science & Technology

    1997-06-01

    DTI has advanced autostereoscopic and field sequential color (FSC) illumination technologies for flat panel displays. Using a patented backlight...technology, DTI has developed prototype 3D flat panel color display that provides stereoscopic viewing without the need for special glasses or other... autostereoscopic viewing. Discussions of system architecture, critical component specifications and resultant display characteristics are provided. Also

  17. Imaging performance of a clinical selenium flat-panel detector for advanced applications in full-field digital mammography

    NASA Astrophysics Data System (ADS)

    Loustauneau, Vincent; Bissonnette, Michel; Cadieux, Sebastien; Hansroul, Marc; Masson, E.; Savard, Serge; Polischuk, Brad T.; Lehtimauki, Mari J.

    2003-06-01

    The advent of digital detectors will enable several advanced imaging applications to be used in the fight against breast cancer. For example, dynamic imaging applications such as tomosynthesis, contrast enhanced and dual energy mammography have demonstrated promising results. In this paper, we will assess the suitability of this detector for these advanced applications. MTF and DQE measurements were performed on a selenium FFDM detector to assess image quality. Ghosting properties of a digital detector are also an important factor, since it can strongly degrade image quality. In this paper, we will also report on the ghosting characteristics of the selenium detector, using typical exposures envisioned to be used in tomosynthesis exams. The physical mechanisms that create ghost images will be discussed and will be quantified.

  18. Advanced solar panel designs

    NASA Technical Reports Server (NTRS)

    Ralph, E. L.; Linder, E.

    1995-01-01

    This paper describes solar cell panel designs that utilize new hgih efficiency solar cells along with lightweight rigid panel technology. The resulting designs push the W/kg and W/sq m parameters to new high levels. These new designs are well suited to meet the demand for higher performance small satellites. This paper reports on progress made on two SBIR Phase 1 contracts. One panel design involved the use of large area (5.5 cm x 6.5 cm) GaAs/Ge solar cells of 19% efficiency combined with a lightweight rigid graphite fiber epoxy isogrid substrate configuration. A coupon (38 cm x 38 cm) was fabricated and tested which demonstrated an array specific power level of 60 W/kg with a potential of reaching 80 W/kg. The second panel design involved the use of newly developed high efficiency (22%) dual junction GaInP2/GaAs/Ge solar cells combined with an advanced lightweight rigid substrate using aluminum honeycomb core with high strength graphite fiber mesh facesheets. A coupon (38 cm x 38 cm) was fabricated and tested which demonstrated an array specific power of 105 W/kg and 230 W/sq m. This paper will address the construction details of the panels and an a analysis of the component weights. A strawman array design suitable for a typical small-sat mission is described for each of the two panel design technologies being studied. Benefits in respect to weight reduction, area reduction, and system cost reduction are analyzed and compared to conventional arrays.

  19. Comparison of concentrating collectors to tracking flat panels

    SciTech Connect

    Jones, G.J.

    1984-01-01

    Two-axis tracking appears to be the economic optimum for photovoltaic flat-panel technology. This requires a new comparison of flat-panel and concentrator arrays using the most competitive flat-panel option. The array field costs for a two-axis tracking flat-panel should be nearly identical to the costs for a concentrator. Therefore, module costs for the two technologies can be compared directly, simplifying the analysis. For example, at southwestern sites, characterized by a high direct-to-diffuse insolation ratio, 12% flat-panels are found to be equivalent to 15% concentrators of the same cost ($/m/sup 2/). For regions with more diffuse radiation the concentrator must be over 18% efficient to be equivalent.

  20. A comparison of concentrating collectors to tracking flat panels

    SciTech Connect

    Jones, G.J.

    1984-05-01

    Two-axis tracking appears to be the economic optimum for photovoltaic flat-panel technology. This requires a new comparison of flatpanel and concentrator arrays using the most competitive flat-panel option. The array field costs for a two-axis tracking flat-panel should be nearly identical to the costs for a concentrator. Therefore, module costs for the two technologies can be compared directly, simplifying the analysis. For example, at southwestern sites, characterized by a high direct-to-diffuse insolation ratio, 12% flat-panels are found to be equivalent to 15% concentrators of the same cost ($/M/sup 2/). For regions with more diffuse radiation the concentrator must be over 18% efficient to be equivalent.

  1. Flat-panel volume CT: fundamental principles, technology, and applications.

    PubMed

    Gupta, Rajiv; Cheung, Arnold C; Bartling, Soenke H; Lisauskas, Jennifer; Grasruck, Michael; Leidecker, Christianne; Schmidt, Bernhard; Flohr, Thomas; Brady, Thomas J

    2008-01-01

    Flat-panel volume computed tomography (CT) systems have an innovative design that allows coverage of a large volume per rotation, fluoroscopic and dynamic imaging, and high spatial resolution that permits visualization of complex human anatomy such as fine temporal bone structures and trabecular bone architecture. In simple terms, flat-panel volume CT scanners can be thought of as conventional multidetector CT scanners in which the detector rows have been replaced by an area detector. The flat-panel detector has wide z-axis coverage that enables imaging of entire organs in one axial acquisition. Its fluoroscopic and angiographic capabilities are useful for intraoperative and vascular applications. Furthermore, the high-volume coverage and continuous rotation of the detector may enable depiction of dynamic processes such as coronary blood flow and whole-brain perfusion. Other applications in which flat-panel volume CT may play a role include small-animal imaging, nondestructive testing in animal survival surgeries, and tissue-engineering experiments. Such versatility has led some to predict that flat-panel volume CT will gain importance in interventional and intraoperative applications, especially in specialties such as cardiac imaging, interventional neuroradiology, orthopedics, and otolaryngology. However, the contrast resolution of flat-panel volume CT is slightly inferior to that of multidetector CT, a higher radiation dose is needed to achieve a comparable signal-to-noise ratio, and a slower scintillator results in a longer scanning time.

  2. [Flat-panel detectors in X-ray systems].

    PubMed

    Spahn, M; Heer, V; Freytag, R

    2003-05-01

    For all application segments X-ray systems with flat-panel detectors increasingly enter the market. In digital radiography,mammography and cardiologic angiography flat-panel detectors are already well established while they are made ready for market introduction in general angiography and fluoroscopy. Two flat-panel detector technologies are available. One technology is based on an indirect conversion process of X-rays while the other one uses a direct conversion method. For radiography and dynamic applications the indirect method provides substantial advantages, while the direct method has some benefits for mammography. In radiography and mammography flat-panel detectors lead to clear improvements with respect to workflow, image quality and dose reduction potentials. These improvements are fostered by the immediate availability of the image, the large dynamic range and the high sensitivity to X-rays. New applications and the use of complex image processing algorithms have the potential to enlarge the present diagnostic range of applications. Up to now, image intensifiers are still the well-established technology for angiography and fluoroscopy. Nevertheless flat-panel detectors begin to enter this field, especially in cardiologic angiography. Characteristics of flat-panel detectors such as the availability of distortion-free images, the excellent contrast resolution, the large dynamic range, the high sensitivity to X-rays and the usability in magnetic fields provide the basis for improved and new diagnostic and interventional methods.

  3. Active noise control using a distributed mode flat panel loudspeaker.

    PubMed

    Zhu, H; Rajamani, R; Dudney, J; Stelson, K A

    2003-07-01

    A flat panel distributed mode loudspeaker (DML) has many advantages over traditional cone speakers in terms of its weight, size, and durability. However, its frequency response is uneven and complex, thus bringing its suitability for active noise control (ANC) under question. This paper presents experimental results demonstrating the effective use of panel DML speakers in an ANC application. Both feedback and feedforward control techniques are considered. Effective feedback control with a flat panel speaker could open up a whole range of new noise control applications and has many advantages over feedforward control. The paper develops a new control algorithm to attenuate tonal noise of a known frequency by feedback control. However, due to the uneven response of the speakers, feedback control is found to be only moderately effective even for this narrow-band application. Feedforward control proves to be most capable for the flat panel speaker. Using feedforward control, the sound pressure level can be significantly reduced in close proximity to an error microphone. The paper demonstrates an interesting application of the flat panel in which the panel is placed in the path of sound and effectively used to block sound transmission using feedforward control. This is a new approach to active noise control enabled by the use of flat panels and can be used to prevent sound from entering into an enclosure in the first place rather than the traditional approach of attempting to cancel sound after it enters the enclosure.

  4. Diffractive optics for compact flat panel displays. Final report

    SciTech Connect

    Sweeney, D.; DeLong, K.

    1997-04-29

    Three years ago LLNL developed a practical method to dramatically reduce the chromatic aberration in single element diffractive imaging lenses. High efficiency, achromatic imaging lenses have been fabricated for human vision correction. This LDRD supported research in applying our new methods to develop a unique, diffraction-based optical interface with solid state, microelectronic imaging devices. Advances in microelectronics have led to smaller, more efficient components for optical systems. There have, however, been no equivalent advances in the imaging optics associated with these devices. The goal of this project was to replace the bulky, refractive optics in typical head-mounted displays with micro-thin diffractive optics to directly image flat-panel displays into the eye. To visualize the system think of the lenses of someone`s eyeglasses becoming flat-panel displays. To realize this embodiment, we needed to solve the problems of large chromatic aberrations and low efficiency that are associated with diffraction. We have developed a graceful tradeoff between chromatic aberrations and the diffractive optic thickness. It turns out that by doubling the thickness of a micro-thin diffractive lens we obtain nearly a two-times improvement in chromatic performance. Since the human eye will tolerate one diopter of chromatic aberration, we are able to achieve an achromatic image with a diffractive lens that is only 20 microns thick, versus 3 mm thickness for the comparable refractive lens. Molds for the diffractive lenses are diamond turned with sub-micron accuracy; the final lenses are cast from these molds using various polymers. We thus retain both the micro- thin nature of the diffractive optics and the achromatic image quality of refractive optics. During the first year of funding we successfully extended our earlier technology from 1 cm diameter optics required for vision applications up to the 5 cm diameter optics required for this application. 3 refs., 6 figs.

  5. Flat or curved thin optical display panel

    DOEpatents

    Veligdan, J.T.

    1995-01-10

    An optical panel includes a plurality of waveguides stacked together, with each waveguide having a first end and an opposite second end. The first ends collectively define a first face, and the second ends collectively define a second face of the panel. The second face is disposed at an acute face angle relative to the waveguides to provide a panel which is relatively thin compared to the height of the second face. In an exemplary embodiment for use in a projection TV, the first face is substantially smaller in height than the second face and receives a TV image, with the second face defining a screen for viewing the image enlarged. 7 figures.

  6. Flat or curved thin optical display panel

    DOEpatents

    Veligdan, James T.

    1995-01-10

    An optical panel 10 includes a plurality of waveguides 12 stacked together, with each waveguide 12 having a first end 12a and an opposite second end 12b. The first ends 12a collectively define a first face 16, and the second ends 12b collectively define a second face 18 of the panel 10. The second face 18 is disposed at an acute face angle relative to the waveguides 12 to provide a panel 10 which is relatively thin compared to the height of the second face. In an exemplary embodiment for use in a projection TV, the first face 16 is substantially smaller in height than the second face 18 and receives a TV image, with the second face 18 defining a screen for viewing the image enlarged.

  7. Advanced surface paneling method for subsonic and supersonic flow

    NASA Technical Reports Server (NTRS)

    Erickson, L. L.; Johnson, F. T.; Ehlers, F. E.

    1976-01-01

    Numerical results illustrating the capabilities of an advanced aerodynamic surface paneling method are presented. The method is applicable to both subsonic and supersonic flow, as represented by linearized potential flow theory. The method is based on linearly varying sources and quadratically varying doublets which are distributed over flat or curved panels. These panels are applied to the true surface geometry of arbitrarily shaped three dimensional aerodynamic configurations.

  8. Software Simulates Sight: Flat Panel Mura Detection

    NASA Technical Reports Server (NTRS)

    2008-01-01

    In the increasingly sophisticated world of high-definition flat screen monitors and television screens, image clarity and the elimination of distortion are paramount concerns. As the devices that reproduce images become more and more sophisticated, so do the technologies that verify their accuracy. By simulating the manner in which a human eye perceives and interprets a visual stimulus, NASA scientists have found ways to automatically and accurately test new monitors and displays. The Spatial Standard Observer (SSO) software metric, developed by Dr. Andrew B. Watson at Ames Research Center, measures visibility and defects in screens, displays, and interfaces. In the design of such a software tool, a central challenge is determining which aspects of visual function to include while accuracy and generality are important, relative simplicity of the software module is also a key virtue. Based on data collected in ModelFest, a large cooperative multi-lab project hosted by the Optical Society of America, the SSO simulates a simplified model of human spatial vision, operating on a pair of images that are viewed at a specific viewing distance with pixels having a known relation to luminance. The SSO measures the visibility of foveal spatial patterns, or the discriminability of two patterns, by incorporating only a few essential components of vision. These components include local contrast transformation, a contrast sensitivity function, local masking, and local pooling. By this construction, the SSO provides output in units of "just noticeable differences" (JND) a unit of measure based on the assumed smallest difference of sensory input detectable by a human being. Herein is the truly amazing ability of the SSO, while conventional methods can manipulate images, the SSO models human perception. This set of equations actually defines a mathematical way of working with an image that accurately reflects the way in which the human eye and mind behold a stimulus. The SSO is

  9. Flat Panel Space Based Space Surveillance Sensor

    NASA Astrophysics Data System (ADS)

    Kendrick, R.; Duncan, A.; Wilm, J.; Thurman, S. T.; Stubbs, D. M.; Ogden, C.

    2013-09-01

    limited telescope is, therefore, replaced by in-process integration and test as part of the PIC fabrication that substantially reduces associated schedule and cost. The low profile and low SWaP of a SPIDER system enables high resolution imaging with a payload that is similar in size and aspect ratio to a solar panel. This allows high resolution low cost options for space based space surveillance telescopes. The low SWaP design enables hosted payloads, cubesat designs as well as traditional bus options that are lower cost. We present a description of the concept and preliminary simulation and experimental data that demonstrate the imaging capabilities of the SPIDER technique.

  10. An improved method for flat-field correction of flat panel x-ray detector.

    PubMed

    Kwan, Alexander L C; Seibert, J Anthony; Boone, John M

    2006-02-01

    In this Technical Note, the effects of different flat-field techniques are examined for a cesium iodide flat panel detector, which exhibited a slightly nonlinear exposure response. The results indicate that the variable flat-field correction method with the appropriate polynomial fit provides excellent correction throughout the entire exposure range. The averaged normalized variation factor, used to assess the nonuniformity of the flat-field correction, decreased from 30.76 for the fixed correction method to 4.13 for the variable flat-field correction method with a fourth-order polynomial fit for the 60 kVp spectrum, and from 16.42 to 3.97 for the 95 kVp spectrum.

  11. Development of Surfaces Optically Suitable for Flat Solar Panels

    NASA Technical Reports Server (NTRS)

    Desmet, D.; Jason, A.

    1978-01-01

    Three areas of research in the development of flat solar panels are described. (1) A reflectometer which can separately evaluate the spectral and diffuse reflectivities of surfaces was developed. The reflectometer has a phase locked detection system. (2) A coating composed of strongly bound copper oxide that is formed by an etching process performed on an aluminum alloy with high copper content was also developed. Because of this one step fabrication process, fabrication costs are expected to be small. (3) A literature search was conducted and conclusions on the required optical properties of flat plate solar collectors are presented.

  12. Investigation of forming curved ablative panels from flat panels for space shuttle

    NASA Technical Reports Server (NTRS)

    Chandler, H. H.

    1972-01-01

    The purpose of this study was to determine the feasibility of reforming flat ablative panels to a curved configuration. The study indicated that if the panels could be shaped to a radius of 2.54 m (100 in.) then 88.7% of the surface area of the orbiter could be covered, and that if they could be shaped to a radius of 3.81 m (150 in.) then 77.2% of the surface could be covered. Two basic approaches were followed to determine the best method for forming the flat panels to a curved shape. The first was to determine if partially cured panels could be formed, allowing the forming heat cycle to complete the curing of the ablator. The second method was to form fully cured flat panels into the desired curvature through a secondary heat cycle. Measurements made on the panels during storage indicated that they continued to straighten out over time. This was attributed to residual stresses locked into the panels that had not been fully relaxed by the heat cycle.

  13. Musculoskeletal applications of flat-panel volume CT.

    PubMed

    Reichardt, Benjamin; Sarwar, Ammar; Bartling, Soenke H; Cheung, Arnold; Grasruck, Michael; Leidecker, Christianne; Bredella, Miriam A; Brady, Thomas J; Gupta, Rajiv

    2008-12-01

    Flat-panel volume computed tomography (fpVCT) is a recent development in imaging. We discuss some of the musculoskeletal applications of a high-resolution flat-panel CT scanner. FpVCT has four main advantages over conventional multidetector computed tomography (MDCT): high-resolution imaging; volumetric coverage; dynamic imaging; omni-scanning. The overall effective dose of fpVCT is comparable to that of MDCT scanning. Although current fpVCT technology has higher spatial resolution, its contrast resolution is slightly lower than that of MDCT (5-10HU vs. 1-3HU respectively). We discuss the efficacy and potential utility of fpVCT in various applications related to musculoskeletal radiology and review some novel applications for pediatric bones, soft tissues, tumor perfusion, and imaging of tissue-engineered bone growth. We further discuss high-resolution CT and omni-scanning (combines fluoroscopic and tomographic imaging).

  14. 75 FR 51286 - Certain Flat Panel Digital Televisions and Components Thereof; Notice of Investigation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-19

    ... COMMISSION Certain Flat Panel Digital Televisions and Components Thereof; Notice of Investigation AGENCY: U.S... importation of certain flat panel digital televisions and components thereof by reason of infringement of... certain flat panel digital televisions and components thereof that infringe one or more of claims 22-25...

  15. Supersonic Panel Flutter Test Results for Flat Fiber-Glass Sandwich Panels with Foamed Cores

    NASA Technical Reports Server (NTRS)

    Tuovila, W. J.; Presnell, John G., Jr.

    1961-01-01

    Flutter tests have been made on flat panels having a 1/4 inch-thick plastic-foam core covered with thin fiber-glass laminates. The testing was done in the Langley Unitary Plan wind tunnel at Mach numbers from 1.76 t o 2.87. The flutter boundary for these panels was found to be near the flutter boundary of thin metal panels when compared on the basis of an equivalent panel stiffness. The results also demonstrated that the depth of the cavity behind the panel has a pronounced influence on flutter. Changing the cavity depth from 1 1/2 inches to 1/2 inch reduced the dynamic pressure at start of flutter by 40 percent. No flutter was obtained when the spacers on the back of the panel were against the bottom of the cavity.

  16. Diffractive flat panel solar concentrators of a novel design.

    PubMed

    de Jong, Ties M; de Boer, Dick K G; Bastiaansen, Cees W M

    2016-07-11

    A novel design for a flat panel solar concentrator is presented which is based on a light guide with a grating applied on top that diffracts light into total internal reflection. By combining geometrical and diffractive optics the geometrical concentration ratio is optimized according to the principles of nonimaging optics, while the thickness of the device is minimized due to the use of total internal reflection.

  17. Plasma technology and its use in flat panel digital radiography.

    PubMed

    Zur, Albert

    2010-01-01

    Plasma DR technology is used to produce a cost effective flat panel x-ray detector that acquires digital x-ray images with excellent diagnostic quality. The detector is radiation hard and permanently zero defect, with a full virtual pixel matrix that has no dead lines, pixels, or dead pixel clusters. The technology also allows the full potential of large area amorphous Selenium imaging to finally be realized (see Figure 4).

  18. Flat panel planar optic display. Revision 4/95

    SciTech Connect

    Veligdan, J.T.

    1995-05-01

    A prototype 10 inch flat panel Planar Optic display, (POD), screen has been constructed and tested. This display screen is comprised of hundreds of planar optic glass sheets bonded together with a cladding layer between each sheet where each glass sheet represents a vertical line of resolution. The display is 9 inches wide by 5 inches high and approximately 1 inch thick. A 3 milliwatt HeNe laser is used as the illumination source and a vector scanning technique is employed.

  19. Flat panel display test and evaluation: procedures, standards, and facilities

    NASA Astrophysics Data System (ADS)

    Jackson, Timothy W.; Daniels, Reginald; Hopper, Darrel G.

    1997-07-01

    This paper addresses flat panel display test and evaluation via a discussion of procedures, standards and facilities. Procedures need to be carefully developed and documented to ensure that test accomplished in separate laboratories produce comparable results. The tests themselves must not be a source of inconsistency in test results when such comparisons are made in the course of procurements or new technology prototype evaluations. Standards are necessary to expedite the transition of the new display technologies into applications and to lower the costs of custom parts applied across disparate applications. The flat panel display industry is in the course of ascertaining and formulating such standards as they are of value to designers, manufacturers, marketers and users of civil and military products and equipment. Additionally, in order to inform the DoD and industry, the test and evaluation facilities of the Air Force Research Laboratory Displays Branch are described. These facilities are available to support procurements involving flat panel displays and to examine new technology prototypes. Finally, other government display testing facilities within the Navy and the Army are described.

  20. Unfolding X-ray spectra using a flat panel detector.

    PubMed

    Gallardo, Sergio; Juste, Belén; Pozuelo, Fausto; Ródenas, José; Querol, Andrea; Verdú, Gumersindo

    2013-01-01

    It is difficult to measure the energy spectrum of X-ray tubes due to the pile up effect produced by the high fluence of photons. Using attenuating materials, appropriate detector devices and the Monte Carlo method, primary X-ray spectrum of these devices can be estimated. In this work, a flat panel detector with a PMMA wedge has been used to obtain a dose curve corresponding to certain working conditions of a radiodiagnostic X-ray tube. The relation between the dose curve recorded by the flat panel and the primary X-ray spectrum is defined by a response function. Normally this function can be approximated by a matrix, which can be obtained by means of the Monte Carlo method. Knowing the measured dose curve and the response matrix, the primary X-ray spectrum can be unfolded. However, there are some problems that strongly affect the applicability of this method: i.e. technical features of the flat panel and inherent characteristics of the involved radiation physics (ill-posed problem). Both aspects are analyzed in this work, concluding that the proposed method can be applied with an acceptable accuracy for spectra without characteristic lines, for instance, tungsten anode in the 50-70 kVp range.

  1. EMI investigation and modeling of a flat panel display

    NASA Astrophysics Data System (ADS)

    Shinde, Satyajeet

    It is often important to carry out EMI analysis in the design phase of an electronic product to predict the radiated emissions. An EMI analysis is important to predict if the product complies with the FCC regulations as well as to gain an understanding of the noise coupling and radiation mechanisms. EMI analysis and prediction of radiated emissions in electronic products that have an electrically large chassis, pose a challenge due to the presence of multiple resonant structures and noise-coupling mechanisms. The study focusses on the investigation of the main noise coupling mechanisms, the approach and methods used for the modeling of a flat panel display. Full-wave simulation models are a powerful tool for the prediction of radiated emissions and the visualization of coupling paths within the product. The first part deals with the measurement of radiated emissions from the display under standard test conditions and the identification of the main noise sources using near-field scanning. The contribution of the chassis components - frame, back cover and the back panel, to the radiated emission is analyzed using shielding measurements. Noise coupling from the main board, flex cables, display driver boards and the display is analyzed from measurements. The second part deals with the full-wave modeling of the components - main board, flex cables, chassis and the display driver boards. The modeling approach is demonstrated by highlighting some of the challenges in modeling larger structures having many details. The simulation model contains the main components of the TV that contribute to far-field radiation. The full-wave modeling is done using the CST Microwave Studio. Two sets of simulation models are described - the common mode models and the complete models. The use of the common mode models for the identification of the resonant structures is demonstrated. The far-field radiated emissions along with the coupling mechanism within the flat panel display can be

  2. Carbon Nanotube Thin Film Transistors for Flat Panel Display Application.

    PubMed

    Liang, Xuelei; Xia, Jiye; Dong, Guodong; Tian, Boyuan; Peng, Lianmao

    2016-12-01

    Carbon nanotubes (CNTs) are promising materials for both high performance transistors for high speed computing and thin film transistors for macroelectronics, which can provide more functions at low cost. Among macroelectronics applications, carbon nanotube thin film transistors (CNT-TFT) are expected to be used soon for backplanes in flat panel displays (FPDs) due to their superior performance. In this paper, we review the challenges of CNT-TFT technology for FPD applications. The device performance of state-of-the-art CNT-TFTs are compared with the requirements of TFTs for FPDs. Compatibility of the fabrication processes of CNT-TFTs and current TFT technologies are critically examined. Though CNT-TFT technology is not yet ready for backplane production line of FPDs, the challenges can be overcome by close collaboration between research institutes and FPD manufacturers in the short term.

  3. Improving the diversity of manufacturing electroluminescent flat panel displays

    SciTech Connect

    Moss, T.S.; Samuels, J.A.; Smith, D.C.

    1995-09-01

    Crystalline calcium thiogallate with a cerium dopant has been deposited by metal-organic chemical vapor deposition (MOCVD) at temperatures below 600{degrees}C on a low cost glass substrate. An EL luminance of 1.05 fL was observed 40 volts above threshold at 60 Hz. This is more than an order of magnitude improvement over earlier crystalline-as-deposited thiogallate materials. These results pave the way for the use of MOCVD as a potential method for processing full color thin-film electroluminescent (TFEL) flat panel displays. The formation of the CaGa{sub 2}S{sub 4}:Ce phosphor requires precise control over a number of deposition parameters including flow rates, substrate temperature, and reactor pressure. The influence of these parameters will be discussed in terms of structure, uniformity, and TFEL device performance.

  4. Flat-panel, full-color, electroluminescent display

    NASA Astrophysics Data System (ADS)

    Robertson, James B.

    1987-08-01

    This invention relates to a flat-panel, electroluminescent display capable of achieving full color and is particularly useful in achieving a bright display with high resolution. The invention uses red, green and blue phosphors in two layers separated by layers of insulating material and layers of electrodes that are used to excite the phosphors. In operation, the display is addressed by supplying sufficient voltage between selected electrodes. This places an electric field across the phosphor at each picture element located between the overlap of the selected electrodes causing the phosphor to emit light at this location. These and other matrix-addressed displays can be addressed line-at-a-time (row or column) fashion in rapid enough sequence to display information at standard TV frame rates.

  5. Flat panel CT detectors for sub-second volumetric scanning

    NASA Astrophysics Data System (ADS)

    Colbeth, Richard E.; Mollov, Ivan P.; Roos, Pieter G.; Shapiro, Edward G.

    2005-04-01

    This paper explores the potential of flat panel detectors in sub-second CT scanning applications. Using a PaxScan 4030CB with 600um thick CsI(Tl), a central section of the panel (16 to 32 rows), was scanned at frame rates up to 1000fps. Using this platform, fundamental issues related to high speed scanning were characterized. The offset drift of the imager over 60 seconds was found to be less than 0.014 ppm/sec relative to full scale. The gain stability over a 10 hour period is better than +/- .45%, which is at the resolution limit of the measurement. Two different types of lag measurements were performed in order to separate the photodiode array lag from the CsI afterglow. The panel lag was found to be 0.41% 1st frame and 0.054% 25th frame at 1000fps. The CsI(Tl) afterglow, however, is roughly an order of magnitude higher, dominating the lag for sub-second scans. At 1000fps the 1st frame lag due to afterglow was 3.3% and the 25th frame lag was 0.34%. Both the lag and afterglow are independent of signal level and each follows a simple power law evolution versus time. Reconstructions of anatomical phantoms and the CATPHAN 500 phantom are presented. With a 2 second, 1200 projection scan of the CATPHAN phantom at 600fps in 32 slice mode, using 120kVp and CTDI100 of 43.2mGy, 0.3% contrast resolution for a 6mm diameter target, can be visualized. In addition, 15lp/cm spatial resolution was achieved with a 2mm slice and a central CTDI100 of 10.8mGy.

  6. Solid-state flat panel imager with avalanche amorphous selenium

    NASA Astrophysics Data System (ADS)

    Scheuermann, James R.; Howansky, Adrian; Goldan, Amir H.; Tousignant, Olivier; Levéille, Sébastien; Tanioka, K.; Zhao, Wei

    2016-03-01

    Active matrix flat panel imagers (AMFPI) have become the dominant detector technology for digital radiography and fluoroscopy. For low dose imaging, electronic noise from the amorphous silicon thin film transistor (TFT) array degrades imaging performance. We have fabricated the first prototype solid-state AMFPI using a uniform layer of avalanche amorphous selenium (a-Se) photoconductor to amplify the signal to eliminate the effect of electronic noise. We have previously developed a large area solid-state avalanche a-Se sensor structure referred to as High Gain Avalanche Rushing Photoconductor (HARP) capable of achieving gains of 75. In this work we successfully deposited this HARP structure onto a 24 x 30 cm2 TFT array with a pixel pitch of 85 μm. An electric field (ESe) up to 105 Vμm-1 was applied across the a-Se layer without breakdown. Using the HARP layer as a direct detector, an X-ray avalanche gain of 15 +/- 3 was achieved at ESe = 105 Vμm-1. In indirect mode with a 150 μm thick structured CsI scintillator, an optical gain of 76 +/- 5 was measured at ESe = 105 Vμm-1. Image quality at low dose increases with the avalanche gain until the electronic noise is overcome at a constant exposure level of 0.76 mR. We demonstrate the success of a solid-state HARP X-ray imager as well as the largest active area HARP sensor to date.

  7. Cryogenic flat-panel gas-gap heat switch

    NASA Astrophysics Data System (ADS)

    Vanapalli, S.; Keijzer, R.; Buitelaar, P.; ter Brake, H. J. M.

    2016-09-01

    A compact additive manufactured flat-panel gas-gap heat switch operating at cryogenic temperature is reported in this paper. A guarded-hot-plate apparatus has been developed to measure the thermal conductance of the heat switch with the heat sink temperature in the range of 100-180 K. The apparatus is cooled by a two-stage GM cooler and the temperature is controlled with a heater and a braided copper wire connection. A thermal guard is mounted on the hot side of the device to confine the heat flow axially through the sample. A gas handling system allows testing the device with different gas pressures in the heat switch. Experiments are performed at various heat sink temperatures, by varying gas pressure in the gas-gap and with helium, hydrogen and nitrogen gas. The measured off-conductance with a heat sink temperature of 115 K and the hot plate at 120 K is 0.134 W/K, the on-conductance with helium and hydrogen gases at the same temperatures is 4.80 W/K and 4.71 W/K, respectively. This results in an on/off conductance ratio of 37 ± 7 and 35 ± 6 for helium and hydrogen respectively. The experimental results matches fairly well with the predicted heat conductance at cryogenic temperatures.

  8. Second generation large area microchannel plate flat panel phototubes

    NASA Astrophysics Data System (ADS)

    Ertley, C. D.; Siegmund, O. H. W.; Jelinsky, S. R.; Tedesco, J.; Minot, M. J.; O'Mahony, A.; Craven, C. A.; Popecki, M.; Lyashenko, A. V.; Foley, M. R.

    2016-07-01

    Very large (20 cm × 20 cm) flat panel phototubes are being developed which employ novel microchannel plates (MCPs). The MCPs are manufactured using borosilicate microcapillary arrays which are functionalized by the application of resistive and secondary emissive layers using atomic layer deposition (ALD). This allows the operational parameters to be set by tailoring sequential ALD deposition processes. The borosilicate substrates are robust, including the ability to be produced in large formats (20 cm square). ALD MCPs have performance characteristics (gain, pulse amplitude distributions, and imaging) that are equivalent or better than conventional MCPs. They have low intrinsic background (0.045 events cm-2 sec-1)., high open area ratios (74% for the latest generation of borosilicate substrates), and stable gain during >7 C cm-2 charge extraction after preconditioning (vacuum bake and burn-in). The tube assemblies use a pair of 20 cm × 20 cm ALD MCPs comprised of a borosilicate entrance window, a proximity focused bialkali photocathode, and a strip-line readout anode. The second generation design employs an all glass body with a hot indium seal and a transfer photocathode. We have achieved >20% quantum efficiency and good gain uniformity over the 400 cm2 field of view, spatial resolution of <1 cm and obtained event timing accuracy of close to 100 ps FWHM.

  9. Sarnoff JND Vision Model for Flat-Panel Design

    NASA Technical Reports Server (NTRS)

    Brill, Michael H.; Lubin, Jeffrey

    1998-01-01

    This document describes adaptation of the basic Sarnoff JND Vision Model created in response to the NASA/ARPA need for a general-purpose model to predict the perceived image quality attained by flat-panel displays. The JND model predicts the perceptual ratings that humans will assign to a degraded color-image sequence relative to its nondegraded counterpart. Substantial flexibility is incorporated into this version of the model so it may be used to model displays at the sub-pixel and sub-frame level. To model a display (e.g., an LCD), the input-image data can be sampled at many times the pixel resolution and at many times the digital frame rate. The first stage of the model downsamples each sequence in time and in space to physiologically reasonable rates, but with minimum interpolative artifacts and aliasing. Luma and chroma parts of the model generate (through multi-resolution pyramid representation) a map of differences-between test and reference called the JND map, from which a summary rating predictor is derived. The latest model extensions have done well in calibration against psychophysical data and against image-rating data given a CRT-based front-end. THe software was delivered to NASA Ames and is being integrated with LCD display models at that facility,

  10. Light sharing in multi-flat-panel-PMT PEM detectors.

    PubMed

    Raylman, Raymond R; Majewski, Stan; Mayhugh, Michael R

    2006-01-01

    Large are a detectors, such as those used in positron emission mammography (PEM) and scintimammography, utilize arrays of discrete semtillator elements mounted on arrays of position sensitive photomultiplier tubes (PSPMT). Scintillator elements can be packed very densely (minimizing area between elements), allowing good detection sensitivity and spatial resolution. And, while new flat panel PSPMTS have minimal inactive edges, when they are placed in arrays significant dead spaces where scintillation light is undetectable are created. To address this problem, a light guide is often placed between the detector and PSPMT array to spread scintillation light so that these gaps can be bridged. In this investigation we studied the effect of light guides of various thickness on system performance. A 10x10 element array of LYSO detector elements was coupled to the center of a 2x2 array of PSPMTs through varying thicknesses (1 to 4 mm) of UV glass. The spot size of the imaged elements and distortions in the regular square pattern of the imaged scintillator arrays were evaluated. Energy resolution was measured by placing single elements of LYSO at several locations of the PSPMT array. Spatial distortions in the images of the array were reduced by using thicker light guides (3-4 mm). Use of thicker light guides, however, resulted in reduced pixel resolution and slight degradation of energy resolution. Therefore, some loss of pixel and energy resolution will accompany the use of thick light guides (minimum of 3 mm) required for optimum identification of detector elements.

  11. Motion-compensated defect interpolation for flat-panel detectors

    NASA Astrophysics Data System (ADS)

    Aach, Til; Barth, Erhardt; Mayntz, Claudia

    2004-05-01

    One advantage of flat-panel X-ray detectors is the immediate availability of the acquired images for display. Current limitations in large-area active-matrix manufacturing technology, however, require that the images read out from such detectors be processed to correct for inactive pixels. In static radiographs, these defects can only be interpolated by spatial filtering. Moving X-ray image modalities, such as fluoroscopy or cine-angiography, permit to use temporal information as well. This paper describes interframe defect interpolation algorithms based on motion compensation and filtering. Assuming the locations of the defects to be known, we fill in the defective areas from past frames, where the missing information was visible due to motion. The motion estimator is based on regularized block matching, with speedup obtained by successive elimination and related measures. To avoid the motion estimator locking on to static defects, these are cut out of each block during matching. Once motion is estimated, three methods are available for defect interpolation: direct filling-in by the motion-compensated predecessor, filling-in by a 3D-multilevel median filtered value, and spatiotemporal mean filtering. Results are shown for noisy fluoroscopy sequences acquired in clinical routine with varying amounts of motion and simulated defects up to six lines wide. They show that the 3D-multilevel median filter appears as the method of choice since it causes the least blur of the interpolated data, is robust with respect to motion estimation errors and works even in non-moving areas.

  12. High voltage protection in active matrix flat-panel imagers

    NASA Astrophysics Data System (ADS)

    Lehnert, Joerg; Zhao, Wei

    2006-03-01

    Various direct and indirect active matrix flat-panel imagers (AMFPI) are being investigated for x-ray imaging. In both direct AMFPI and indirect AMFPI with avalanche gain, a bias potential up to several thousand volts is required to operate the photoconductor. Under the condition of a large amount of radiation exposure between subsequent readout, a potential >80 V could appear across the amorphous silicon (a-Si) thin film transistor (TFT) and cause permanent damage. The purpose of this paper is to investigate a simple pixel design for high voltage protection. The pixel electrode acts as an additional gate for the top channel of an a-Si TFT to drain excess image charge from the pixel electrode until an equilibrium is reached where the TFT channel current equals the detector signal current at a predetermined safe maximum value V Pmax for the pixel potential. This "dual-gate" TFT structure without additional protective device simplifies the TFT array design and improves yield. However special care is required to understand the characteristics of both the top and the bottom gates to ensure sufficient detector dynamic range as well as reliable high voltage protection. A physical model for dual-gate a-Si TFTs was developed and device parameters were determined by fitting the model to measured characteristics from a dual-gate TFT array. Our results showed that compared to the bottom (normal) gate, the protective gate has a shallower transfer characteristics (i.e. channel current as a function of gate voltage) due to a higher density of states in the top interface. Nevertheless it provides adequate protection of the TFT with V Pmax of ~40 V for typical radiographic exposures.

  13. Heat Transfar Properties of Flat-Panel Evacuated Porous Insrlators

    NASA Astrophysics Data System (ADS)

    Yoneno, Hirosyi; Yamamoto, Ryoichi

    Flat Panel evacuated porous insulators have been produced by filling powder or fiber (such as perlite powder, diatomaceous earth powder, silica aerogel powder, g lass fiber and ceramic fiber) in film-like laminated plastic container and by evacuating to form vacuum in it is interior. Heat transfer properties of these evacuated insulators have been studied under various conditions (such as particle diameter, surface area, packing density, solid volume fraction and void dimension). The apparent mean thermal conductivity has been measured for the boundary surface temperature at cold face temperature 13°C and hot face temperature 35°. The effect of air pressure ranging from 1 Pa to one atomosphere (105 Pa) was examined. The results were as follows. (1) For each powder the apparent mean thermal conductivity decreases with decreasing residual air pressure, and at very low pressure bellow 1 -103 Pa the conductivity becomes indeqendent of pressure. The thermal conductivity at 1.3Pa is 0.0053 W/mK for perlite powder, 0.0048W/mK for diatomaceous earth powder, 0.0043 W/mK for silica aerogel powder and 0.0029W/mK for glass fiber. (2) With decreasing particle size, the apparent mean thermal conductivity is constant independent of residual air pressure in higher pressure region. It is that void dimension continues to decrease with particle size and the mean free path of air becomes comparable with void dimension. (3) In the range of minor solid volume fraction, the apparent mean thermal conductivity at very low precreases with decreasing particle size. This shows the thermal contact resistance of the solid particle increases with decreasing particle size.

  14. Focal spot measurements using a digital flat panel detector

    PubMed Central

    Jain, Amit; Panse, A.; Bednarek, Daniel R.; Rudin, Stephen

    2014-01-01

    Focal spot size is one of the crucial factors that affect the image quality of any x-ray imaging system. It is, therefore, important to measure the focal spot size accurately. In the past, pinhole and slit measurements of x-ray focal spots were obtained using direct exposure film. At present, digital detectors are replacing film in medical imaging so that, although focal spot measurements can be made quickly with such detectors, one must be careful to account for the generally poorer spatial resolution of the detector and the limited usable magnification. For this study, the focal spots of a diagnostic x-ray tube were measured with a 10-μm pinhole using a 194-μm pixel flat panel detector (FPD). The two-dimensional MTF, measured with the Noise Response (NR) Method was used for the correction for the detector blurring. The resulting focal spot sizes based on the FWTM (Full Width at Tenth Maxima) were compared with those obtained with a very high resolution detector with 8-μm pixels. This study demonstrates the possible effect of detector blurring on the focal spot size measurements with digital detectors with poor resolution and the improvement obtained by deconvolution. Additionally, using the NR method for measuring the two-dimensional MTF, any non-isotropies in detector resolution can be accurately corrected for, enabling routine measurement of non-isotropic x-ray focal spots. This work presents a simple, accurate and quick quality assurance procedure for measurements of both digital detector properties and x-ray focal spot size and distribution in modern x-ray imaging systems. PMID:25302004

  15. Focal spot measurements using a digital flat panel detector

    NASA Astrophysics Data System (ADS)

    Jain, Amit; Panse, A.; Bednarek, Daniel R.; Rudin, Stephen

    2014-03-01

    Focal spot size is one of the crucial factors that affect the image quality of any x-ray imaging system. It is, therefore, important to measure the focal spot size accurately. In the past, pinhole and slit measurements of x-ray focal spots were obtained using direct exposure film. At present, digital detectors are replacing film in medical imaging so that, although focal spot measurements can be made quickly with such detectors, one must be careful to account for the generally poorer spatial resolution of the detector and the limited usable magnification. For this study, the focal spots of a diagnostic x-ray tube were measured with a 10-μm pinhole using a 194-μm pixel flat panel detector (FPD). The twodimensional MTF, measured with the Noise Response (NR) Method was used for the correction for the detector blurring. The resulting focal spot sizes based on the FWTM (Full Width at Tenth Maxima) were compared with those obtained with a very high resolution detector with 8-μm pixels. This study demonstrates the possible effect of detector blurring on the focal spot size measurements with digital detectors with poor resolution and the improvement obtained by deconvolution. Additionally, using the NR method for measuring the two-dimensional MTF, any non-isotropies in detector resolution can be accurately corrected for, enabling routine measurement of non-isotropic x-ray focal spots. This work presents a simple, accurate and quick quality assurance procedure for measurements of both digital detector properties and x-ray focal spot size and distribution in modern x-ray imaging systems.

  16. Focal spot measurements using a digital flat panel detector.

    PubMed

    Jain, Amit; Panse, A; Bednarek, Daniel R; Rudin, Stephen

    2014-03-19

    Focal spot size is one of the crucial factors that affect the image quality of any x-ray imaging system. It is, therefore, important to measure the focal spot size accurately. In the past, pinhole and slit measurements of x-ray focal spots were obtained using direct exposure film. At present, digital detectors are replacing film in medical imaging so that, although focal spot measurements can be made quickly with such detectors, one must be careful to account for the generally poorer spatial resolution of the detector and the limited usable magnification. For this study, the focal spots of a diagnostic x-ray tube were measured with a 10-μm pinhole using a 194-μm pixel flat panel detector (FPD). The two-dimensional MTF, measured with the Noise Response (NR) Method was used for the correction for the detector blurring. The resulting focal spot sizes based on the FWTM (Full Width at Tenth Maxima) were compared with those obtained with a very high resolution detector with 8-μm pixels. This study demonstrates the possible effect of detector blurring on the focal spot size measurements with digital detectors with poor resolution and the improvement obtained by deconvolution. Additionally, using the NR method for measuring the two-dimensional MTF, any non-isotropies in detector resolution can be accurately corrected for, enabling routine measurement of non-isotropic x-ray focal spots. This work presents a simple, accurate and quick quality assurance procedure for measurements of both digital detector properties and x-ray focal spot size and distribution in modern x-ray imaging systems.

  17. Proposed first edition of the standard for flat-plate photovoltaic modules and panels, UL 1703

    SciTech Connect

    Not Available

    1984-09-12

    The tentative requirements provided cover flat-plate photovoltaic modules and panels intended for installation on or integral with buildings or to be freestanding (that is, not attached to buildings). Modules and panels intended for use in systems with a maximum system voltage of 1000 volts or less are covered. Also covered are components intended to provide electrical connection to and mounting facilities for flat-plate photovoltaic modules and panels. The requirements do not cover equipment intended to accept the electrical output from the array (such as inverters and batteries), tracking mechanisms, cell assemblies intended to operate under concentrated sunlight, optical concentrators, or combination photovoltaic-thermal modules or panels. (LEW)

  18. Effect of Boundary Conditions on the Back Face Deformations of Flat UHMWPE Panels

    DTIC Science & Technology

    2014-12-01

    Molecular-Weight- Polyethylene (UHMWPE). Spherical projectiles were used at velocities in which the panels were not perforated. In our study, we used three...carried out a series of ballistic experiments to investigate the BFD in flat panels made of Ultra-High-Molecular-Weight- Polyethylene (UHMWPE... Polyethylene (UHMWPE) flat plates.” ARL-TR-6943, Army Research Laboratory, May 2014. 4. Doug Faux, Mark Garcia, Michael J. King, Scott Groves, Bob

  19. Feasibility of Flat Panel Detector CT in Perfusion Assessment of Brain Arteriovenous Malformations: Initial Clinical Experience.

    PubMed

    Garcia, M; Okell, T W; Gloor, M; Chappell, M A; Jezzard, P; Bieri, O; Byrne, J V

    2017-02-16

    The different results from flat panel detector CT in various pathologies have provoked some discussion. Our aim was to assess the role of flat panel detector CT in brain arteriovenous malformations, which has not yet been assessed. Five patients with brain arteriovenous malformations were studied with flat panel detector CT, DSC-MR imaging, and vessel-encoded pseudocontinuous arterial spin-labeling. In glomerular brain arteriovenous malformations, perfusion was highest next to the brain arteriovenous malformation with decreasing values with increasing distance from the lesion. An inverse tendency was observed in the proliferative brain arteriovenous malformation. Flat panel detector CT, originally thought to measure blood volume, correlated more closely with arterial spin-labeling-CBF and DSC-CBF than with DSC-CBV. We conclude that flat panel detector CT perfusion depends on the time point chosen for data collection, which is triggered too early in these patients (ie, when contrast agent appears in the superior sagittal sinus after rapid shunting through the brain arteriovenous malformation). This finding, in combination with high data variability, makes flat panel detector CT inappropriate for perfusion assessment in brain arteriovenous malformations.

  20. Testing and analysis of flat and curved panels with multiple cracks

    NASA Technical Reports Server (NTRS)

    Broek, David; Jeong, David Y.; Thomson, Douglas

    1994-01-01

    An experimental and analytical investigation of multiple cracking in various types of test specimens is described in this paper. The testing phase is comprised of a flat unstiffened panel series and curved stiffened and unstiffened panel series. The test specimens contained various configurations for initial damage. Static loading was applied to these specimens until ultimate failure, while loads and crack propagation were recorded. This data provides the basis for developing and validating methodologies for predicting linkup of multiple cracks, progression to failure, and overall residual strength. The results from twelve flat coupon and ten full scale curved panel tests are presented. In addition, an engineering analysis procedure was developed to predict multiple crack linkup. Reasonable agreement was found between predictions and actual test results for linkup and residual strength for both flat and curved panels. The results indicate that an engineering analysis approach has the potential to quantitatively assess the effect of multiple cracks in the arrest capability of an aircraft fuselage structure.

  1. C-arm CT with XRIIs and digital flat panels: a review

    NASA Astrophysics Data System (ADS)

    Fahrig, Rebecca; Ganguly, Arundhuti; Starman, Jared D.; Strobel, Norbert K.

    2004-10-01

    C-arm CT first emerged as a useful high-contrast imaging modality in the late 1990s, using an XRII as the large area x-ray detector. To date, the C-arm approach to intra-procedural 3D imaging has primarily been used for high-contrast imaging tasks. The emerging goal for these systems is to extend the imaging range into the area of soft-tissue, and it is thought that digital flat-panel detectors may help. Flat panels replace the analog image intensifier, the camera optics, the pickup tube and the analog-to-digital converter with an all-digital detector. Flat panel detectors have a linear response, do not require distortion correction, do not suffer from veiling glare or blooming, and have higher dynamic range that current XRIIs. On the other hand, XRIIs have greater flexibility in FOV, and could support higher frame rates at high resolution, thereby reducing the effects of view aliasing. We have experience with a typical XRII-based C-arm imaging system and a new high-end C-arm equipped with a large flat-panel detector. Initial investigations show that when projection pixel size, acquisition geometry and focal spot size are matched, the flat-panel-based system produces reconstructions with improved MTF, primarily due to the additional interpolation step required for XRII warp correction. Investigations of artifact levels and comparison with in vivo CT images are presented.

  2. Flat-panel-detector-based volume tomographic angiography imaging: detector evaluation

    NASA Astrophysics Data System (ADS)

    Ning, Ruola; Zhang, Dinghua; Chen, Biao; Conover, David L.; Yu, Rongfeng

    1999-09-01

    Recent development of large area flat panel solid state detector arrays indicates that flat panel image sensors have some common potential advantages: compactness, absence of geometric distortion and veiling glare with the benefits of high resolution, high DQE, high frame rate and high dynamic range, small image lag (less than 1%) and excellent linearity (approximately 1%). The advantages of the new flat-panel detector make it a promising candidate for cone beam volume tomographic angiography imaging. The purpose of this study is to characterize a Selenium thin film transistor (STFT) flat panel detector-based imaging system for cone beam volume tomographic angiography imaging applications. A prototype STFT detector-based cone beam volume tomographic angiography imaging system has been designed and constructed based on the modification of a GE 8800 CT scanner. This system is evaluated using a vascular phantom with different x-ray spectra, different sizes of vessels and different iodine concentration levels. The results indicate that with the currently available STFT flat panel detector, 90 kVp is the optimal kVp to achieve the highest signal-to-noise ratio for volume tomographic angiography imaging and the low contrast resolution of the system is 4 mg/ml iodine for a 2 mm vessel.

  3. Flat-panel see-through three-dimensional display based on integral imaging.

    PubMed

    Takaki, Yasuhiro; Yamaguchi, Yuta

    2015-04-15

    This study proposes a technique to construct a flat-panel see-through three-dimensional (3D) display based on integral imaging. This display consists of multiple lens arrays, a transparent flat-panel display, and a light-blocking wall (LBW). Rays behind the display are reconstructed in front of it by combination of the lens arrays and the LBW to provide the see-through function. The combination of one of the lens arrays and the transparent flat-panel display produces full-parallax 3D images, which are superimposed on background images. The experimental system is constructed to verify the proposed technique. The see-through and superposition capabilities of the experimental system are demonstrated.

  4. Investigations of a flat-panel detector for quality assurance measurements in ion beam therapy.

    PubMed

    Hartmann, Bernadette; Telsemeyer, Julia; Huber, Lucas; Ackermann, Benjamin; Jäkel, Oliver; Martišíková, Mária

    2012-01-07

    Increased accuracy in radiation delivery to a patient provided by scanning particle beams leads to high demands on quality assurance (QA). To meet the requirements, an extensive quality assurance programme has been implemented at the Heidelberg Ion Beam Therapy Center. Currently, high-resolution radiographic films are used for beam spot position measurements and homogeneity measurements for scanned fields. However, given that using this film type is time and equipment demanding, considerations have been made to replace the radiographic films in QA by another appropriate device. In this study, the suitability of the flat-panel detector RID 256 L based on amorphous silicon was investigated as an alternative method. The currently used radiographic films were taken as a reference. Investigations were carried out for proton and carbon ion beams. The detectors were irradiated simultaneously to allow for a direct comparison. The beam parameters (e.g. energy, focus, position) currently used in the daily QA procedures were applied. Evaluation of the measurements was performed using newly implemented automatic routines. The results for the flat-panel detector were compared to the standard radiographic films. Additionally, a field with intentionally decreased homogeneity was applied to test the detector's sensitivities toward possible incorrect scan parameters. For the beam position analyses, the flat-panel detector results showed good agreement with radiographic films. For both detector types, deviations between measured and planned spot distances were found to be below 1% (1 mm). In homogeneously irradiated fields, the flat-panel detector showed a better dose response homogeneity than the currently used radiographic film. Furthermore, the flat-panel detector is sensitive to field irregularities. The flat-panel detector was found to be an adequate replacement for the radiographic film in QA measurements. In addition, it saves time and equipment because no post

  5. Recommendations for the performance rating of flat plate terrestrial photovoltaic solar panels

    NASA Technical Reports Server (NTRS)

    Treble, F. C.

    1976-01-01

    A review of recommendations for standardizing the performance rating of flat plate terrestrial solar panels is given to develop an international standard code of practice for performance rating. Required data to characterize the performance of a solar panel are listed. Other items discussed are: (1) basic measurement procedures; (2) performance measurement in natural sunlight and simulated sunlight; (3) standard solar cells; (4) the normal incidence method; (5) global method and (6) definition of peak power.

  6. Beam-Steerable Flat-Panel Reflector Antenna

    NASA Technical Reports Server (NTRS)

    Lee, Choon Sae; Lee, Chanam; Miranda, Felix A.

    2005-01-01

    Many space applications require a high-gain antenna that can be easily deployable in space. Currently, the most common high-gain antenna for space-born applications is an umbrella-type reflector antenna that can be folded while being lifted to the Earth orbit. There have been a number of issues to be resolved for this type of antenna. The reflecting surface of a fine wire mesh has to be light in weight and flexible while opening up once in orbit. Also the mesh must be a good conductor at the operating frequency. In this paper, we propose a different type of high-gain antenna for easy space deployment. The proposed antenna is similar to reflector antennas except the curved main reflector is replaced by a flat reconfigurable surface for easy packing and deployment in space. Moreover it is possible to steer the beam without moving the entire antenna system.

  7. 76 FR 9360 - In the Matter of Certain Flat Panel Digital Televisions and Components Thereof; Notice of a...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-17

    ... COMMISSION In the Matter of Certain Flat Panel Digital Televisions and Components Thereof; Notice of a... within the United States after importation of certain flat panel digital televisions and components... named the following respondents: LG Electronics, Inc. of South Korea and LG Electronics, Inc....

  8. Image quality of flat-panel cone beam CT

    NASA Astrophysics Data System (ADS)

    Rose, Georg; Wiegert, Jens; Schaefer, Dirk; Fiedler, Klaus; Conrads, Norbert; Timmer, Jan; Rasche, Volker; Noordhoek, Niels; Klotz, Erhard; Koppe, Reiner

    2003-06-01

    We present results on 3D image quality in terms of spatial resolution (MTF) and low contrast detectability, obtained on a flat dynamic X-ray detector (FD) based cone-beam CT (CB-CT) setup. Experiments have been performed on a high precision bench-top system with rotating object table, fixed X-ray tube and 176 x 176 mm2 active detector area (Trixell Pixium 4800). Several objects, including CT performance-, MTF- and pelvis phantoms, have been scanned under various conditions, including a high dose setup in order to explore the 3D performance limits. Under these optimal conditions, the system is capable of resolving less than 1% (~10 HU) contrast in a water background. Within a pelvis phantom, even inserts of muscle and fat equivalent are clearly distinguishable. This also holds for fast acquisitions of up to 40 fps. Focusing on the spatial resolution, we obtain an almost isotropic three-dimensional resolution of up to 30 lp/cm at 10% modulation.

  9. Using Flat-Panel Perfusion Imaging to Measure Cerebral Hemodynamics

    PubMed Central

    Lin, Chung-Jung; Guo, Wan-Yuo; Chang, Feng-Chi; Hung, Sheng-Che; Chen, Ko-Kung; Yu, Deuerling-Zheng; Wu, Chun-Hsien Frank; Liou, Jy-Kang Adrian

    2016-01-01

    Abstract Flat-detector CT perfusion (FD-CTP) imaging has demonstrated efficacy in qualitatively accessing the penumbra in acute stroke equivalent to that of magnetic resonance perfusion (MRP). The aim of our study was to evaluate the feasibility of quantifying oligemia in the brain in patients with carotid stenosis. Ten patients with unilateral carotid stenosis of >70% were included. All MRPs and FD-CTPs were performed before stenting. Region-of-interests (ROIs) including middle cerebral artery territory at basal ganglia level on both stenotic and contralateral sides were used for quantitative analysis. Relative time to peak (rTTP) was defined as TTP of the stenotic side divided by TTP of the contralateral side, and so as relative cerebral blood volume (rCBV), relative mean transit time (rMTT), and relative cerebral blood flow (rCBF). Absolute and relative TTP, CBV, MTT, CBF between two modalities were compared. For absolute quantitative analysis, the correlation of TTP was highest (r = 0.56), followed by CBV (r = 0.47), MTT (r = 0.47), and CBF (r = 0.43); for relative quantitative analysis, rCBF was the highest (r = 0.79), followed by rTTP (r = 0.75) and rCBV (r = 0.50). We confirmed that relative quantitative assessment of FD-CTP is feasible in chronic ischemic disease. Absolute quantitative measurements between MRP and FD-CTP only expressed moderate correlations. Optimization of acquisitions and algorithms is warranted to achieve better quantification. PMID:27196456

  10. Dynamic chest radiography: flat-panel detector (FPD) based functional X-ray imaging.

    PubMed

    Tanaka, Rie

    2016-07-01

    Dynamic chest radiography is a flat-panel detector (FPD)-based functional X-ray imaging, which is performed as an additional examination in chest radiography. The large field of view (FOV) of FPDs permits real-time observation of the entire lungs and simultaneous right-and-left evaluation of diaphragm kinetics. Most importantly, dynamic chest radiography provides pulmonary ventilation and circulation findings as slight changes in pixel value even without the use of contrast media; the interpretation is challenging and crucial for a better understanding of pulmonary function. The basic concept was proposed in the 1980s; however, it was not realized until the 2010s because of technical limitations. Dynamic FPDs and advanced digital image processing played a key role for clinical application of dynamic chest radiography. Pulmonary ventilation and circulation can be quantified and visualized for the diagnosis of pulmonary diseases. Dynamic chest radiography can be deployed as a simple and rapid means of functional imaging in both routine and emergency medicine. Here, we focus on the evaluation of pulmonary ventilation and circulation. This review article describes the basic mechanism of imaging findings according to pulmonary/circulation physiology, followed by imaging procedures, analysis method, and diagnostic performance of dynamic chest radiography.

  11. Flat tensile specimen design for advanced composites

    NASA Technical Reports Server (NTRS)

    Worthem, Dennis W.

    1990-01-01

    Finite element analyses of flat, reduced gage section tensile specimens with various transition region contours were performed. Within dimensional constraints, such as maximum length, tab region width, gage width, gage length, and minimum tab length, a transition contour radius of 41.9 cm produced the lowest stress values in the specimen transition region. The stresses in the transition region were not sensitive to specimen material properties. The stresses in the tab region were sensitive to specimen composite and/or tab material properties. An evaluation of stresses with different specimen composite and tab material combinations must account for material nonlinearity of both the tab and the specimen composite. Material nonlinearity can either relieve stresses in the composite under the tab or elevate them to cause failure under the tab.

  12. Multiple-gain-ranging readout method to extend the dynamic range of amorphous silicon flat-panel imagers

    NASA Astrophysics Data System (ADS)

    Roos, Pieter G.; Colbeth, Richard E.; Mollov, Ivan; Munro, Peter; Pavkovich, John; Seppi, Edward J.; Shapiro, Edward G.; Tognina, Carlo A.; Virshup, Gary F.; Yu, J. Micheal; Zentai, George; Kaissl, Wolfgang; Matsinos, Evangelos; Richters, Jeroen; Riem, Heinrich

    2004-05-01

    The dynamic range of many flat panel imaging systems are fundamentally limited by the dynamic range of the charge amplifier and readout signal processing. We developed two new flat panel readout methods that achieve extended dynamic range by changing the read out charge amplifier feedback capacitance dynamically and on a real-time basis. In one method, the feedback capacitor is selected automatically by a level sensing circuit, pixel-by-pixel, based on its exposure level. Alternatively, capacitor selection is driven externally, such that each pixel is read out two (or more) times, each time with increased feedback capacitance. Both methods allow the acquisition of X-ray image data with a dynamic range approaching the fundamental limits of flat panel pixels. Data with an equivalent bit depth of better than 16 bits are made available for further image processing. Successful implementation of these methods requires careful matching of selectable capacitor values and switching thresholds, with the imager noise and sensitivity characteristics, to insure X-ray quantum limited operation over the whole extended dynamic range. Successful implementation also depends on the use of new calibration methods and image reconstruction algorithms, to insure artifact free rebuilding of linear image data by the downstream image processing systems. The multiple gain ranging flat panel readout method extends the utility of flat panel imagers and paves the way to new flat panel applications, such as cone beam CT. We believe that this method will provide a valuable extension to the clinical application of flat panel imagers.

  13. Flat panel display using Ti-Cr-Al-O thin film

    DOEpatents

    Jankowski, Alan F.; Schmid, Anthony P.

    2002-01-01

    Thin films of Ti--Cr--Al--O are used as a resistor material. The films are rf sputter deposited from ceramic targets using a reactive working gas mixture of Ar and O.sub.2. Resistivity values from 10.sup.4 to 10.sup.10 Ohm-cm have been measured for Ti--Cr--Al--O film <1 .mu.m thick. The film resistivity can be discretely selected through control of the target composition and the deposition parameters. The application of Ti--Cr--Al--O as a thin film resistor has been found to be thermodynamically stable, unlike other metal-oxide films. The Ti--Cr--Al--O film can be used as a vertical or lateral resistor, for example, as a layer beneath a field emission cathode in a flat panel display; or used to control surface emissivity, for example, as a coating on an insulating material such as vertical wall supports in flat panel displays.

  14. Second-generation flat panel displays for the enhanced Abrahms M1 battlefield tank

    NASA Astrophysics Data System (ADS)

    Mahdi, Ken F.; Wyrembelski, Rick J.; Hatton, Terry J.

    1997-07-01

    The Abrams M1 Battlefield Tank has undergone several phases of performance enhancements since its introduction, improvements have covered updates to all the major components of the vehicle with major emphasis on the vetronics and man-machine interface. Through these enhancements of M1 has pioneered the utilization of flat panel display (FPD) technologies and the M1A2 version has an FPD at both the driver and gunner stations and a third at the commander position. These FPDs all employ electroluminescent (EL) imaging technology that is well suited for the severe vetronics environment. The latest M1A2 enhancements, being introduced as part of the M1A2 System Enhancement Package, include a flat panel AMLCD color tactical display which supersedes the earlier monochrome EL FPD used in this application, and a high resolution monochrome EL FPD for the second generation FLIR sensor, which supersedes the earlier bulky CRT display.

  15. Attenuated phase-shift mask (PSM) blanks for flat panel display

    NASA Astrophysics Data System (ADS)

    Kageyama, Kagehiro; Mochizuki, Satoru; Yamakawa, Hiroyuki; Uchida, Shigeru

    2015-10-01

    The fine pattern exposure techniques are required for Flat Panel display applications as smart phone, tablet PC recently. The attenuated phase shift masks (PSM) are being used for ArF and KrF photomask lithography technique for high end pattern Semiconductor applications. We developed CrOx based large size PSM blanks that has good uniformity on optical characteristics for FPD applications. We report the basic optical characteristics and uniformity, stability data of large sized CrOx PSM blanks.

  16. Development of Design, Test and Acquisition Criteria for Aircraft Dot-Matrix Flat Panel Display Systems

    DTIC Science & Technology

    1985-09-01

    SUB. R Flat-Panel Dot-Matrix Displays, Color, Alphanumeric, 23 07 Video, LED, Grey Scale, Luminance, Optical Coupling, 23 11 Contrast, Legibility...based flight simulations and bench test experiments. SPECIFICS Method Utilizing the bottom-up methodology, the electro- optical % characteristics and...switches, with emphasis on the optical effects of fingerprints, and on techniques for optimizing the interpret- ability of rapidly time changing numeric

  17. Qualification test results for DOE solar photovoltaic flat panel procurement - PRDA 38

    NASA Technical Reports Server (NTRS)

    Griffith, J. S.

    1980-01-01

    Twelve types of prototypes modules for the DOE Photovoltaic Flat Panel Procurement (PRDA 38) were subjected to qualification tests at the Jet Propulsion Laboratory according to a new specification. Environmental exposures were carried out separately and included temperature cycling, humidity, wind simulation, and hail. The most serious problems discovered were reduced insulation resistance to ground and ground continuity of the metal frames, electrical degradation, erratic power readings, and delamination. The electrical and physical characteristics of the newly received modules are also given.

  18. Flat-panel electronic displays: a triumph of physics, chemistry and engineering.

    PubMed

    Hilsum, Cyril

    2010-03-13

    This paper describes the history and science behind the development of modern flat-panel displays, and assesses future trends. Electronic displays are an important feature of modern life. For many years the cathode ray tube, an engineering marvel, was universal, but its shape was cumbersome and its operating voltage too high. The need for a flat-panel display, working at a low voltage, became imperative, and much research has been applied to this need. Any versatile flat-panel display will exploit an electro-optical effect, a transparent conductor and an addressing system to deliver data locally. The first need is to convert an electrical signal into a visible change. Two methods are available, the first giving emission of light, the second modulating ambient illumination. The most useful light-emitting media are semiconductors, historically exploiting III-V or II-VI compounds, but more recently organic or polymer semiconductors. Another possible effect uses gas plasma discharges. The modulating, or subtractive, effects that have been studied include liquid crystals, electrophoresis, electrowetting and electrochromism. A transparent conductor makes it possible to apply a voltage to an extended area while observing the results. The design is a compromise, since the free electrons that carry current also absorb light. The first materials used were metals, but some semiconductors, when heavily doped, give a better balance, with high transmission for a low resistance. Delivering data unambiguously to a million or so picture elements across the display area is no easy task. The preferred solution is an amorphous silicon thin-film transistor deposited at each cross-point in an X-Y matrix. Success in these endeavours has led to many applications for flat-panel displays, including television, flexible displays, electronic paper, electronic books and advertising signs.

  19. Flat-panel electronic displays: a triumph of physics, chemistry and engineering

    PubMed Central

    Hilsum, Cyril

    2010-01-01

    This paper describes the history and science behind the development of modern flat-panel displays, and assesses future trends. Electronic displays are an important feature of modern life. For many years the cathode ray tube, an engineering marvel, was universal, but its shape was cumbersome and its operating voltage too high. The need for a flat-panel display, working at a low voltage, became imperative, and much research has been applied to this need. Any versatile flat-panel display will exploit an electro-optical effect, a transparent conductor and an addressing system to deliver data locally. The first need is to convert an electrical signal into a visible change. Two methods are available, the first giving emission of light, the second modulating ambient illumination. The most useful light-emitting media are semiconductors, historically exploiting III–V or II–VI compounds, but more recently organic or polymer semiconductors. Another possible effect uses gas plasma discharges. The modulating, or subtractive, effects that have been studied include liquid crystals, electrophoresis, electrowetting and electrochromism. A transparent conductor makes it possible to apply a voltage to an extended area while observing the results. The design is a compromise, since the free electrons that carry current also absorb light. The first materials used were metals, but some semiconductors, when heavily doped, give a better balance, with high transmission for a low resistance. Delivering data unambiguously to a million or so picture elements across the display area is no easy task. The preferred solution is an amorphous silicon thin-film transistor deposited at each cross-point in an X–Y matrix. Success in these endeavours has led to many applications for flat-panel displays, including television, flexible displays, electronic paper, electronic books and advertising signs. PMID:20123746

  20. High-performance flat-panel solar thermoelectric generators with high thermal concentration.

    PubMed

    Kraemer, Daniel; Poudel, Bed; Feng, Hsien-Ping; Caylor, J Christopher; Yu, Bo; Yan, Xiao; Ma, Yi; Wang, Xiaowei; Wang, Dezhi; Muto, Andrew; McEnaney, Kenneth; Chiesa, Matteo; Ren, Zhifeng; Chen, Gang

    2011-05-01

    The conversion of sunlight into electricity has been dominated by photovoltaic and solar thermal power generation. Photovoltaic cells are deployed widely, mostly as flat panels, whereas solar thermal electricity generation relying on optical concentrators and mechanical heat engines is only seen in large-scale power plants. Here we demonstrate a promising flat-panel solar thermal to electric power conversion technology based on the Seebeck effect and high thermal concentration, thus enabling wider applications. The developed solar thermoelectric generators (STEGs) achieved a peak efficiency of 4.6% under AM1.5G (1 kW m(-2)) conditions. The efficiency is 7-8 times higher than the previously reported best value for a flat-panel STEG, and is enabled by the use of high-performance nanostructured thermoelectric materials and spectrally-selective solar absorbers in an innovative design that exploits high thermal concentration in an evacuated environment. Our work opens up a promising new approach which has the potential to achieve cost-effective conversion of solar energy into electricity.

  1. A new x-ray imaging technique for radiography mode of flat-panel imager

    NASA Astrophysics Data System (ADS)

    Suzuki, K.; Ikeda, S.; Ueda, K.; Baba, R.

    2007-03-01

    A digital radiography system using a flat-panel imager, which has a novel imaging technique for a radiography mode, has been developed. A radiographic image captured by the new imaging technique has a wide dynamic range in comparison with conventional radiographic images. The purpose of this presentation is to show the basic performance of the image quality acquired by the new imaging technique and compare it with an image taken by a conventional technique. The flat-panel imager has a gain switching capability, normally used in a dynamic imaging mode for a cone-beam CT study. The gain switching method has two gain settings and switches between them automatically, depending on the incident dose to each pixel of flat-panel imager. As a result of the gain switching method, an image having wide dynamic range is achieved. In this study, we applied the gain switching method to the radiography mode, and achieved a radiographic image with wider dynamic range than a conventional radiograph. Furthermore, we have also developed an algorithm for calibration of the gain switching method in radiography mode.

  2. Rotational flat-panel computed tomography in diagnostic and interventional neuroradiology.

    PubMed

    Dörfler, A; Struffert, T; Engelhorn, T; Richter, G

    2008-10-01

    Originally aimed at improving standard radiography by providing higher absorption efficiency and a wider dynamic range than available with X-ray film or film-screen combinations, flat-panel detector technology has become widely accepted for neuroangiographic imaging. In particular flat-panel detector computed tomography (FD-CT) which uses rotational C-arm-mounted flat-panel detector technology is capable of volumetric imaging with high spatial resolution. As "Angiographic CT" FD-CT may be helpful during many diagnostic and neurointerventional procedures, i.e. intracranial stenting for cerebrovascular stenoses, stent-assisted coil embolization of wide-necked cerebral aneurysms and embolizations of arteriovenous malformations. By providing morphologic, CT-like images of the brain within the angio suite, FD-CT is able to rapidly visualize periprocedural hemorrhage and may thus improve rapid complication management without the need for patient transfer. In addition, myelography and postmyelographic FD-CT imaging can be carried out using a single machine. Spinal interventions, such as kyphoplasty or vertebroplasty might also benefit from FD-CT. This paper briefly reviews the technical principles of FD technology and then focuses on possible applications in diagnostic and interventional neuroradiology.

  3. Direct-conversion flat-panel x-ray imaging: reduction of noise by presampling filtration

    NASA Astrophysics Data System (ADS)

    Rowlands, John A.; Ji, Winston G.; Zhao, Wei; Lee, Denny L. Y.

    2000-04-01

    Large area flat panel solid-state detectors are being studied for digital radiography and fluoroscopy. Such systems use active matrix arrays to readout latent charge images created either by direct conversion of x-ray energy to charge in a photoconductor or indirectly using a phosphor and individual photodiodes on the active matrix array. Our work has utilized the direct conversion method because of its simplicity and the higher resolution possible due to the electrostatic collection of secondary quanta. Aliasing of noise occurs in current designs of direct detectors based on amorphous selenium ((alpha) -Se) because of its high intrinsic resolution. This aliasing leads to a decrease in detective quantum efficiency (DQE) as frequency increases. It has been predicted, using a previously developed model of the complete imaging system, that appropriately controlled spatial filtration can reduce this aliased noise and hence increase DQE at the Nyquist frequency, fNY. Our purpose is to experimentally verify this concept by implementing presampling filtration in a practical flat panel system. An (alpha) -Se based flat panel imager is modified by incorporating an insulating layer between the active matrix and the (alpha) -Se layer to introduce a predetermined amount of presampling burring. The modified imager is evaluated using standard linear analysis tools, modulation transfer function (MTF), noise power spectra (NPS) and DQE(f), and the results are compared to theoretical predictions.

  4. Microcalcification detection using cone-beam CT mammography with a flat-panel imager.

    PubMed

    Gong, Xing; Vedula, Aruna A; Glick, Stephen J

    2004-06-07

    The purpose of this study was to investigate microcalcification detectability using CT mammography with a flat-panel imager. To achieve this, a computer simulation was developed to model an amorphous-silicon, CsI based flat-panel imager system using a linear cascaded model. The breast was modelled as a hemi-ellipsoid shape with composition of 50% adipose and 50% glandular tissue. Microcalcifications were modelled as small spheres having a composition of calcium carbonate. The results show that with a mean glandular dose equivalent to that typically used in two-view screening mammography, CT mammography with a flat-panel detector is capable of providing images where most microcalcifications are detectable. A receiver operating characteristic (ROC) study was conducted by five physicist observers viewing simulated CT mammography reconstructions. The results suggest that the microcalcification with its diameter equal to or greater than 0.175 mm can be detected with an average area under the ROC curve (AUC) greater than 0.95 using 0.1 or 0.2 mm pixelized detectors. The results also indicate that the optimal pixel size of the detector is around 0.2 mm for microcalcification detection, based on the trade-off between detectability of microcalcifications and the time required for data acquisition and reconstruction.

  5. Evaluation of image quality and dose on a flat-panel CT-scanner

    NASA Astrophysics Data System (ADS)

    Grasruck, M.; Suess, Ch.; Stierstorfer, K.; Popescu, S.; Flohr, T.

    2005-04-01

    We developed and evaluated a prototype flat-panel detector based Volume CT (VCT) scanner. We focused on improving the image quality using different detector settings and reducing x-ray scatter intensities. For the presented results we used a Varian 4030CB flat-panel detector mounted in a multislice CT-gantry (Siemens Medical Systems). The scatter intensities may severely impair image quality in flat-panel detector CT systems. To reduce the impact of scatter we tested bowtie shaped filters, anti-scatter grids and post-processing correction algorithms. We evaluated the improvement of image quality by each method and also by a combination of the several methods. To achieve an extended dynamic range in the projection data, we implemented a novel dynamic gain-switching mode. The read out charge amplifier feedback capacitance is changing dynamically in this mode, depending on the signal level. For this scan mode dedicated corrections in the offset and gain calibration are required. We compared image quality in terms of low contrast for both, the dynamic mode and the standard fixed gain mode. VCT scanners require different types of dose parameters. We measured the dose in a 16 cm CTDI phantom and free air in the scanners iso-center and defined a new metric for a VCT dose index (VCTDI). The dose for a high quality VCT scan of this prototype scanner varied between 15 and 40 mGy.

  6. Thermal Reactor Model for Large-Scale Algae Cultivation in Vertical Flat Panel Photobioreactors.

    PubMed

    Endres, Christian H; Roth, Arne; Brück, Thomas B

    2016-04-05

    Microalgae can grow significantly faster than terrestrial plants and are a promising feedstock for sustainable value added products encompassing pharmaceuticals, pigments, proteins and most prominently biofuels. As the biomass productivity of microalgae strongly depends on the cultivation temperature, detailed information on the reactor temperature as a function of time and geographical location is essential to evaluate the true potential of microalgae as an industrial feedstock. In the present study, a temperature model for an array of vertical flat plate photobioreactors is presented. It was demonstrated that mutual shading of reactor panels has a decisive effect on the reactor temperature. By optimizing distance and thickness of the panels, the occurrence of extreme temperatures and the amplitude of daily temperature fluctuations in the culture medium can be drastically reduced, while maintaining a high level of irradiation on the panels. The presented model was developed and applied to analyze the suitability of various climate zones for algae production in flat panel photobioreactors. Our results demonstrate that in particular Mediterranean and tropical climates represent favorable locations. Lastly, the thermal energy demand required for the case of active temperature control is determined for several locations.

  7. Radiation dose reduction using a CdZnTe-based computed tomography system: Comparison to flat-panel detectors

    SciTech Connect

    Le, Huy Q.; Ducote, Justin L.; Molloi, Sabee

    2010-03-15

    Purpose: Although x-ray projection mammography has been very effective in early detection of breast cancer, its utility is reduced in the detection of small lesions that are occult or in dense breasts. One drawback is that the inherent superposition of parenchymal structures makes visualization of small lesions difficult. Breast computed tomography using flat-panel detectors has been developed to address this limitation by producing three-dimensional data while at the same time providing more comfort to the patients by eliminating breast compression. Flat panels are charge integrating detectors and therefore lack energy resolution capability. Recent advances in solid state semiconductor x-ray detector materials and associated electronics allow the investigation of x-ray imaging systems that use a photon counting and energy discriminating detector, which is the subject of this article. Methods: A small field-of-view computed tomography (CT) system that uses CdZnTe (CZT) photon counting detector was compared to one that uses a flat-panel detector for different imaging tasks in breast imaging. The benefits afforded by the CZT detector in the energy weighting modes were investigated. Two types of energy weighting methods were studied: Projection based and image based. Simulation and phantom studies were performed with a 2.5 cm polymethyl methacrylate (PMMA) cylinder filled with iodine and calcium contrast objects. Simulation was also performed on a 10 cm breast specimen. Results: The contrast-to-noise ratio improvements as compared to flat-panel detectors were 1.30 and 1.28 (projection based) and 1.35 and 1.25 (image based) for iodine over PMMA and hydroxylapatite over PMMA, respectively. Corresponding simulation values were 1.81 and 1.48 (projection based) and 1.85 and 1.48 (image based). Dose reductions using the CZT detector were 52.05% and 49.45% for iodine and hydroxyapatite imaging, respectively. Image-based weighting was also found to have the least beam

  8. Radiation dose reduction using a CdZnTe-based computed tomography system: Comparison to flat-panel detectors

    PubMed Central

    Le, Huy Q.; Ducote, Justin L.; Molloi, Sabee

    2010-01-01

    Purpose: Although x-ray projection mammography has been very effective in early detection of breast cancer, its utility is reduced in the detection of small lesions that are occult or in dense breasts. One drawback is that the inherent superposition of parenchymal structures makes visualization of small lesions difficult. Breast computed tomography using flat-panel detectors has been developed to address this limitation by producing three-dimensional data while at the same time providing more comfort to the patients by eliminating breast compression. Flat panels are charge integrating detectors and therefore lack energy resolution capability. Recent advances in solid state semiconductor x-ray detector materials and associated electronics allow the investigation of x-ray imaging systems that use a photon counting and energy discriminating detector, which is the subject of this article. Methods: A small field-of-view computed tomography (CT) system that uses CdZnTe (CZT) photon counting detector was compared to one that uses a flat-panel detector for different imaging tasks in breast imaging. The benefits afforded by the CZT detector in the energy weighting modes were investigated. Two types of energy weighting methods were studied: Projection based and image based. Simulation and phantom studies were performed with a 2.5 cm polymethyl methacrylate (PMMA) cylinder filled with iodine and calcium contrast objects. Simulation was also performed on a 10 cm breast specimen. Results: The contrast-to-noise ratio improvements as compared to flat-panel detectors were 1.30 and 1.28 (projection based) and 1.35 and 1.25 (image based) for iodine over PMMA and hydroxylapatite over PMMA, respectively. Corresponding simulation values were 1.81 and 1.48 (projection based) and 1.85 and 1.48 (image based). Dose reductions using the CZT detector were 52.05% and 49.45% for iodine and hydroxyapatite imaging, respectively. Image-based weighting was also found to have the least beam

  9. Evaluation of the mechanical stability of a megavoltage imaging system using a new flat panel positioner

    NASA Astrophysics Data System (ADS)

    Morin, O.; Chen, J.; Aubin, M.; Pouliot, J.

    2005-04-01

    Mega-Voltage systems are used in radiation oncology both for external radiation delivery and patient positioning prior to treatment. A pair of portal images compared with digitally reconstructed radiographs is currently the gold standard for positioning but new developments have made possible the use of Mega-Voltage Cone Beam CT for better 3D setup. The non-ideal imaging geometry of the treatment unit has a direct impact on both methods. It led to the use of a reticule attachment as reference for the scale and the isocenter position on the portal images. The reticule has limited precision and occasionally super-imposes anatomical information. As for Cone Beam, the image quality crucially depends on the knowledge of the scan geometry during the acquisition. The reproducibility of the detector position at each angle will affect the image reconstruction and determine how frequently geometrical calibration must be performed. The objectives of this study are to measure the flex of the detector and evaluate its reproducibility. A RID 1640 Perkin Elmer a-Si Flat Panel is installed on a Siemens Primus linear accelerator with a positioner similar the the one used in the Oncor product. Three original methods are used to investigate the behavior in space and time of the imaging system. A reticule and a Plumb Bob tip are placed along the line formed by the isocenter and the source. Their positions projected on the flat panel for different gantry positions are used to calculate the mechanical flex. Projection matrices obtained in a geometrical Cone Beam calibration are also used to quantify the flat panel sagging. Six full sets of data were acquired over a period of 5 months and recorded overall mechanical flexes of 1 and 3 mm for the transversal and longitudinal directions respectively. The absolute magnitude of the flat panel displacement varies slightly with the method used but the discrepancy stays within the laser precision used for alignment. The small standard deviations

  10. Indirect flat-panel detector with avalanche gain: Fundamental feasibility investigation for SHARP-AMFPI (scintillator HARP active matrix flat panel imager)

    SciTech Connect

    Zhao Wei; Li Dan; Reznik, Alla; Lui, B.J.M.; Hunt, D.C.; Rowlands, J.A.; Ohkawa, Yuji; Tanioka, Kenkichi

    2005-09-15

    An indirect flat-panel imager (FPI) with avalanche gain is being investigated for low-dose x-ray imaging. It is made by optically coupling a structured x-ray scintillator CsI(Tl) to an amorphous selenium (a-Se) avalanche photoconductor called HARP (high-gain avalanche rushing photoconductor). The final electronic image is read out using an active matrix array of thin film transistors (TFT). We call the proposed detector SHARP-AMFPI (scintillator HARP active matrix flat panel imager). The advantage of the SHARP-AMFPI is its programmable gain, which can be turned on during low dose fluoroscopy to overcome electronic noise, and turned off during high dose radiography to avoid pixel saturation. The purpose of this paper is to investigate the important design considerations for SHARP-AMFPI such as avalanche gain, which depends on both the thickness d{sub Se} and the applied electric field E{sub Se} of the HARP layer. To determine the optimal design parameter and operational conditions for HARP, we measured the E{sub Se} dependence of both avalanche gain and optical quantum efficiency of an 8 {mu}m HARP layer. The results were used in a physical model of HARP as well as a linear cascaded model of the FPI to determine the following x-ray imaging properties in both the avalanche and nonavalanche modes as a function of E{sub Se}: (1) total gain (which is the product of avalanche gain and optical quantum efficiency); (2) linearity; (3) dynamic range; (4) gain nonuniformity resulting from thickness nonuniformity; and (5) effects of direct x-ray interaction in HARP. Our results showed that a HARP layer thickness of 8 {mu}m can provide adequate avalanche gain and sufficient dynamic range for x-ray imaging applications to permit quantum limited operation over the range of exposures needed for radiography and fluoroscopy.

  11. Indirect flat-panel detector with avalanche gain: fundamental feasibility investigation for SHARP-AMFPI (scintillator HARP active matrix flat panel imager).

    PubMed

    Zhao, Wei; Li, Dan; Reznik, Alla; Lui, B J M; Hunt, D C; Rowlands, J A; Ohkawa, Yuji; Tanioka, Kenkichi

    2005-09-01

    An indirect flat-panel imager (FPI) with avalanche gain is being investigated for low-dose x-ray imaging. It is made by optically coupling a structured x-ray scintillator CsI(Tl) to an amorphous selenium (a-Se) avalanche photoconductor called HARP (high-gain avalanche rushing photoconductor). The final electronic image is read out using an active matrix array of thin film transistors (TFT). We call the proposed detector SHARP-AMFPI (scintillator HARP active matrix flat panel imager). The advantage of the SHARP-AMFPI is its programmable gain, which can be turned on during low dose fluoroscopy to overcome electronic noise, and turned off during high dose radiography to avoid pixel saturation. The purpose of this paper is to investigate the important design considerations for SHARP-AMFPI such as avalanche gain, which depends on both the thickness d(Se) and the applied electric field E(Se) of the HARP layer. To determine the optimal design parameter and operational conditions for HARP, we measured the E(Se) dependence of both avalanche gain and optical quantum efficiency of an 8 microm HARP layer. The results were used in a physical model of HARP as well as a linear cascaded model of the FPI to determine the following x-ray imaging properties in both the avalanche and nonavalanche modes as a function of E(Se): (1) total gain (which is the product of avalanche gain and optical quantum efficiency); (2) linearity; (3) dynamic range; (4) gain nonuniformity resulting from thickness nonuniformity; and (5) effects of direct x-ray interaction in HARP. Our results showed that a HARP layer thickness of 8 microm can provide adequate avalanche gain and sufficient dynamic range for x-ray imaging applications to permit quantum limited operation over the range of exposures needed for radiography and fluoroscopy.

  12. Designing, Modeling, Constructing, and Testing a Flat Panel Speaker and Sound Diffuser for a Simulator

    NASA Technical Reports Server (NTRS)

    Dillon, Christina

    2013-01-01

    The goal of this project was to design, model, build, and test a flat panel speaker and frame for a spherical dome structure being made into a simulator. The simulator will be a test bed for evaluating an immersive environment for human interfaces. This project focused on the loud speakers and a sound diffuser for the dome. The rest of the team worked on an Ambisonics 3D sound system, video projection system, and multi-direction treadmill to create the most realistic scene possible. The main programs utilized in this project, were Pro-E and COMSOL. Pro-E was used for creating detailed figures for the fabrication of a frame that held a flat panel loud speaker. The loud speaker was made from a thin sheet of Plexiglas and 4 acoustic exciters. COMSOL, a multiphysics finite analysis simulator, was used to model and evaluate all stages of the loud speaker, frame, and sound diffuser. Acoustical testing measurements were utilized to create polar plots from the working prototype which were then compared to the COMSOL simulations to select the optimal design for the dome. The final goal of the project was to install the flat panel loud speaker design in addition to a sound diffuser on to the wall of the dome. After running tests in COMSOL on various speaker configurations, including a warped Plexiglas version, the optimal speaker design included a flat piece of Plexiglas with a rounded frame to match the curvature of the dome. Eight of these loud speakers will be mounted into an inch and a half of high performance acoustic insulation, or Thinsulate, that will cover the inside of the dome. The following technical paper discusses these projects and explains the engineering processes used, knowledge gained, and the projected future goals of this project

  13. System design and implementation for the glass panel alignment and sealing tool for flat panel displays

    SciTech Connect

    Jordan, J.D.; Stromberg, P.G.; Kuszmaul, S.S.

    1996-10-16

    This report describes the system designed and fabricated for the National Center for Advanced Information Component Manufacturing (NCAICM) project number 9322-135. The system is a device capable of simultaneously aligning two glass plates and sealing them together with glass frit. The process development was divided into two phases. The first was thermal sealing in an ambient environment. The second was sealing a controlled environment in a vacuum.

  14. Dual-exposure technique for extending the dynamic range of x-ray flat panel detectors.

    PubMed

    Sisniega, A; Abella, M; Desco, M; Vaquero, J J

    2014-01-20

    This work presents an approach to extend the dynamic range of x-ray flat panel detectors by combining two acquisitions of the same sample taken with two different x-ray photon flux levels and the same beam spectral configuration. In order to combine both datasets, the response of detector pixels was modelled in terms of mean and variance using a linear model. The model was extended to take into account the effect of pixel saturation. We estimated a joint probability density function (j-pdf) of the pixel values by assuming that each dataset follows an independent Gaussian distribution. This j-pdf was used for estimating the final pixel value of the high-dynamic-range dataset using a maximum likelihood method. The suitability of the pixel model for the representation of the detector signal was assessed using experimental data from a small-animal cone-beam micro-CT scanner equipped with a flat panel detector. The potential extension in dynamic range offered by our method was investigated for generic flat panel detectors using analytical expressions and simulations. The performance of the proposed dual-exposure approach in realistic imaging environments was compared with that of a regular single-exposure technique using experimental data from two different phantoms. Image quality was assessed in terms of signal-to-noise ratio, contrast, and analysis of profiles drawn on the images. The dynamic range, measured as the ratio between the exposure for saturation and the exposure equivalent to instrumentation noise, was increased from 76.9 to 166.7 when using our method. Dual-exposure results showed higher contrast-to-noise ratio and contrast resolution than the single-exposure acquisitions for the same x-ray dose. In addition, image artifacts were reduced in the combined dataset. This technique to extend the dynamic range of the detector without increasing the dose is particularly suited to image samples that contain both low and high attenuation regions.

  15. Dual-exposure technique for extending the dynamic range of x-ray flat panel detectors

    NASA Astrophysics Data System (ADS)

    Sisniega, A.; Abella, M.; Desco, M.; Vaquero, J. J.

    2014-01-01

    This work presents an approach to extend the dynamic range of x-ray flat panel detectors by combining two acquisitions of the same sample taken with two different x-ray photon flux levels and the same beam spectral configuration. In order to combine both datasets, the response of detector pixels was modelled in terms of mean and variance using a linear model. The model was extended to take into account the effect of pixel saturation. We estimated a joint probability density function (j-pdf) of the pixel values by assuming that each dataset follows an independent Gaussian distribution. This j-pdf was used for estimating the final pixel value of the high-dynamic-range dataset using a maximum likelihood method. The suitability of the pixel model for the representation of the detector signal was assessed using experimental data from a small-animal cone-beam micro-CT scanner equipped with a flat panel detector. The potential extension in dynamic range offered by our method was investigated for generic flat panel detectors using analytical expressions and simulations. The performance of the proposed dual-exposure approach in realistic imaging environments was compared with that of a regular single-exposure technique using experimental data from two different phantoms. Image quality was assessed in terms of signal-to-noise ratio, contrast, and analysis of profiles drawn on the images. The dynamic range, measured as the ratio between the exposure for saturation and the exposure equivalent to instrumentation noise, was increased from 76.9 to 166.7 when using our method. Dual-exposure results showed higher contrast-to-noise ratio and contrast resolution than the single-exposure acquisitions for the same x-ray dose. In addition, image artifacts were reduced in the combined dataset. This technique to extend the dynamic range of the detector without increasing the dose is particularly suited to image samples that contain both low and high attenuation regions.

  16. Performance requirements for electronic displays of color moving images using flat panel technology

    NASA Astrophysics Data System (ADS)

    Glenn, William E.

    1994-04-01

    The initial market for flat panel displays has been dominated by the laptop computer. This is a very attractive entry market for the newer technologies. The technical requirements for computer displays are much easier to satisfy then for high definition entertainment displays. While the resolutions are similar, the other requirements of contrast ratio, cost, light output, response time, uniformity, gray scale, size and color purity are all much less demanding than those for the display of real-time moving images for entertainment. However, if the panels being developed for computers could meet the requirements of entertainment television, they could be used as light valves in large screen projectors. In this way the investment in development and in manufacturing facilities can be amortized over a much larger market. This paper will review a comparison of the requirements for both applications.

  17. Test and Analysis of Foam Impacting a 6x6 Inch RCC Flat Panel

    NASA Technical Reports Server (NTRS)

    Lessard, Wendy B.

    2006-01-01

    This report presents the testing and analyses of a foam projectile impacting onto thirteen 6x6 inch flat panels at a 90 degrees incidence angle. The panels tested in this investigation were fabricated of Reinforced-Carbon-Carbon material and were used to aid in the validation of an existing material model, MAT58. The computational analyses were performed using LS-DYNA, which is a physics-based, nonlinear, transient, finite element code used for analyzing material responses subjected to high impact forces and other dynamic conditions. The test results were used to validate LS-DYNA predictions and to determine the threshold of damage generated by the MAT58 cumulative damage material model. The threshold of damage parameter represents any external or internal visible RCC damage detectable by nondestructive evaluation techniques.

  18. Impact damage resistance of flat glass/cellular glass solar mirror experimental panels

    NASA Technical Reports Server (NTRS)

    Varner, J. R.; Akbar Ali, M.; Adams, M. A.

    1983-01-01

    An attempt is made to characterize the hail-impact behavior of a solar concentrator structural material which consists of thin, second-surface silvered glass sheets bonded to structural support panels of cellular glass. The resulting glass/cellular glass panel can be described as a thin, brittle plate supported by an elastic foundation, with the adhesive bonding the two as a third component. The plate will bend during impact. Attention is experimentally given to how variations in the characteristics or geometry of the flat glass, adhesive and cellular glass affect hail-impact damage resistance. The critical energy needed to cause impact damage is calculated from the critical velocity of the iceball by means of the kinetic energy formula. The complexity of this structural system and the variability of the specimens render it impossible to completely develop an analytical treatment for the prediction of impact damage resistance.

  19. Autostereoscopic 3D flat panel display using an LCD-pixel-associated parallax barrier

    NASA Astrophysics Data System (ADS)

    Chen, En-guo; Guo, Tai-liang

    2014-05-01

    This letter reports an autostereoscopic three-dimensional (3D) flat panel display system employing a newly designed LCD-pixel-associated parallax barrier (LPB). The barrier's parameters can be conveniently determined by the LCD pixels and can help to greatly simplify the conventional design. The optical system of the proposed 3D display is built and simulated to verify the design. For further experimental demonstration, a 508-mm autostereoscopic 3D display prototype is developed and it presents good stereoscopic images. Experimental results agree well with the simulation, which reveals a strong potential for 3D display applications.

  20. [Screening chest X-ray examination with kinetic analysis using flat-panel detector].

    PubMed

    Sanada, Shigeru; Tanaka, Rie; Kobayashi, Takeshi; Suzuki, Masayuki; Inoue, Hitoshi

    2003-11-01

    We are developing dynamic screening radiography to provide kinetic information for lung respiratory examination using a flat-panel-detector (FPD) system. We modified the FPD system (CANON CXDI-22) to take sequential images for a short period of time (10 seconds, 3 frames/sec). Sequential chest radiographs from full inspiration to expiration were taken and analyzed for diaphragm movement and density changes in local lung areas to objectively detect respiratory anomalies. Our methods derived some respiratory functions such as regional air passage and lung structure movement, and suggested that the degree of chronic obstructive pulmonary disease and interstitial pneumonia could be evaluated quantitatively.

  1. High-speed readout for the H8500 flat panel PSPMT

    NASA Astrophysics Data System (ADS)

    Orsolini Cencelli, Valentino; de Notaristefani, Francesco; D'Abramo, Enrico

    2007-02-01

    In this paper we present a new readout system for the H8500 flat panel photomultiplier. The system is based on the MAX1320 analog-to-digital converter and reads all of 64 anodic signals simultaneously at a rate that approaches the 250 ksample/s typical of MAX1320 with a resolution of 14 bits. The data are read through an FPGA by a chip computer, the ETRAX 100LX, and either transmitted via Ethernet or stored on a USB mass storage device.

  2. Postbuckling analysis of shear deformable composite flat panels taking into account geometrical imperfections

    NASA Technical Reports Server (NTRS)

    Librescu, L.; Stein, M.

    1990-01-01

    The effects of initial geometrical imperfections on the postbuckling response of flat laminated composite panels to uniaxial and biaxial compressive loading are investigated analytically. The derivation of the mathematical model on the basis of first-order transverse shear deformation theory is outlined, and numerical results for perfect and imperfect, single-layer and three-layer square plates with free-free, clamped-clamped, or free-clamped edges are presented in graphs and briefly characterized. The present approach is shown to be more accurate than analyses based on the classical Kirchhoff plate model.

  3. Scaling the Non-linear Impact Response of Flat and Curved Composite Panels

    NASA Technical Reports Server (NTRS)

    Ambur, Damodar R.; Chunchu, Prasad B.; Rose, Cheryl A.; Feraboli, Paolo; Jackson, Wade C.

    2005-01-01

    The application of scaling laws to thin flat and curved composite panels exhibiting nonlinear response when subjected to low-velocity transverse impact is investigated. Previous research has shown that the elastic impact response of structural configurations exhibiting geometrically linear response can be effectively scaled. In the present paper, a preliminary experimental study is presented to assess the applicability of the scaling laws to structural configurations exhibiting geometrically nonlinear deformations. The effect of damage on the scalability of the structural response characteristics, and the effect of scale on damage development are also investigated. Damage is evaluated using conventional methods including C-scan, specimen de-plying and visual inspection of the impacted panels. Coefficient of restitution and normalized contact duration are also used to assess the extent of damage. The results confirm the validity of the scaling parameters for elastic impacts. However, for the panels considered in the study, the extent and manifestation of damage do not scale according to the scaling laws. Furthermore, the results indicate that even though the damage does not scale, the overall panel response characteristics, as indicated by contact force profiles, do scale for some levels of damage.

  4. Perfusion analysis using a wide coverage flat-panel volume CT: feasibility study

    NASA Astrophysics Data System (ADS)

    Grasruck, M.; Gupta, R.; Reichardt, B.; Klotz, E.; Schmidt, B.; Flohr, T.

    2007-03-01

    We developed a Flat-panel detector based Volume CT (VCT) prototype scanner with large z-coverage. In that prototype scanner a Varian 4030CB a-Si flat-panel detector was mounted in a multi slice CT-gantry (Siemens Medical Solutions) which provides a 25 cm field of view with 18 cm z-coverage at isocenter. The large volume covered in one rotation can be used for visualization of complete organs of small animals, e.g. rabbits. By implementing a mode with continuous scanning, we are able to reconstruct the complete volume at any point in time during the propagation of a contrast bolus. Multiple volumetric reconstructions over time elucidate the first pass dynamics of a bolus of contrast resulting in 4-D angiography and potentially allowing whole organ perfusion analysis. We studied to which extent pixel based permeability and blood volume calculation with a modified Patlak approach was possible. Experimental validation was performed by imaging evolution of contrast bolus in New Zealand rabbits. Despite the short circulation time of a rabbit, the temporal resolution was sufficient to visually resolve various phases of the first pass of the contrast bolus. Perfusion imaging required substantial spatial smoothing but allowed a qualitative discrimination of different types of parenchyma in brain and liver. If a true quantitative analysis is possible, requires further studies.

  5. Transmission type flat-panel X-ray source using ZnO nanowire field emitters

    SciTech Connect

    Chen, Daokun; Song, Xiaomeng; Zhang, Zhipeng; Chen, Jun; Li, Ziping; She, Juncong; Deng, Shaozhi; Xu, Ningsheng

    2015-12-14

    A transmission type flat-panel X-ray source in diode structure was fabricated. Large-scale patterned ZnO nanowires grown on a glass substrate by thermal oxidation were utilized as field emitters, and tungsten thin film coated on silica glass was used as the transmission anode. Uniform distribution of X-ray generation was achieved, which benefited from the uniform electron emission from ZnO nanowires. Self-ballasting effect induced by the intrinsic resistance of ZnO nanowire and decreasing of screening effect caused by patterned emitters account for the uniform emission. Characteristic X-ray peaks of W-L lines and bremsstrahlung X-rays have been observed under anode voltages at a range of 18–20 kV, the latter of which were the dominant X-ray signals. High-resolution X-ray images with spatial resolution less than 25 μm were obtained by the flat-panel X-ray source. The high resolution was attributed to the small divergence angle of the emitted X-rays from the transmission X-ray source.

  6. Flat-panel detector-based cone beam volume CT breast imaging: detector evaluation

    NASA Astrophysics Data System (ADS)

    Yu, Yong; Conover, David L.; Ning, Ruola

    2003-06-01

    Preliminary evaluation of large-area flat panel detectors (FPDs) indicates that FPDs have some potential advantages over film-screen and CCD-based imagers: compactness, high resolution, high frame rate, large dynamic range, small image lag (<1%), and excellent linearity (~1%). A real time large-area flat panel detector (FPD) Varian PaxScan 2520 was evaluated for cone-beam volume breast imaging (CBVCTBI) in terms of dynamic range, linearity, image lag, and spatial as well as low contrast resolution. In addition, specially made breast phantoms were imaged with our prototyped CBVCTBI system to provide real outcomes to evaluate the detector under full imaging system conditions including the x-ray source, gantry geometry, x-ray technique selection, data acquisition system and reconstruction algorithms. We have concentrated on the low kVp range (30 to 80 kVp) in the context of the breast-imaging task. For ~288 images/scan the exposure required was ~2.5mR/projection. This is equivalent to that of a conventional mammography screening exam. The results indicate that the FPD-based CBVCTBI system can achieve sufficient high- and low-contrast resolution for diagnostic CBVCT breast imaging with a clinically acceptable exposure level. The advantages of the new FPD make it a promising candidate for CBVCTBI.

  7. View-dependent geometric calibration for offset flat-panel cone beam computed tomography systems

    NASA Astrophysics Data System (ADS)

    Nguyen, Van-Giang

    2016-04-01

    Geometric parameters that define the geometry of imaging systems are crucial for image reconstruction and image quality in x-ray computed tomography (CT). The problem of determining geometric parameters for an offset flat-panel cone beam CT (CBCT) system, a recently introduced modality with a large field of view, with the assumption of an unstable mechanism and geometric parameters that vary in each view, is considered. To accurately and rapidly find the geometric parameters for each projection view, we use the projection matrix method and design a dedicated phantom that is partially visible in all projection views. The phantom consists of balls distributed symmetrically in a cylinder to ensure the inclusion of the phantom in all views, and a large portion of the phantom is covered in the projection image. To efficiently use calibrated geometric information in the reconstruction process and get rid of approximation errors, instead of decomposing the projection matrix into actual geometric parameters that are manually corrected before being used in reconstruction, as in conventional methods, we directly use the projection matrix and its pseudo-inverse in projection and backprojection operations of reconstruction algorithms. The experiments illustrate the efficacy of the proposed method with a real offset flat-panel CBCT system in dental imaging.

  8. Physical properties of a new flat panel detector with cesium-iodide technology

    NASA Astrophysics Data System (ADS)

    Hahn, Andreas; Penchev, Petar; Fiebich, Martin

    2016-03-01

    Flat panel detectors have become the standard technology in projection radiography. Further progress in detector technology will result in an improvement of MTF and DQE. The new detector (DX-D45C; Agfa; Mortsel/Belgium) is based on cesium-iodine crystals and has a change in the detector material and the readout electronics. The detector has a size of 30 cm x 24 cm and a pixel matrix of 2560 x 2048 with a pixel pitch of 124 μm. The system includes an automatic exposure detector, which enables the use of the detector without a connection to the x-ray generator. The physical properties of the detector were determined following IEC 62220-1-1 in a laboratory setting. The MTF showed an improvement compared to the previous version of cesium-iodine based flat-panel detectors. Thereby the DQE is also improved especially for the higher frequencies. The new detector showed an improvement in the physical properties compared to the previous versions. This enables a potential for further dose reductions in clinical imaging.

  9. An iterative algorithm for soft tissue reconstruction from truncated flat panel projections

    NASA Astrophysics Data System (ADS)

    Langan, D.; Claus, B.; Edic, P.; Vaillant, R.; De Man, B.; Basu, S.; Iatrou, M.

    2006-03-01

    The capabilities of flat panel interventional x-ray systems continue to expand, enabling a broader array of medical applications to be performed in a minimally invasive manner. Although CT is providing pre-operative 3D information, there is a need for 3D imaging of low contrast soft tissue during interventions in a number of areas including neurology, cardiac electro-physiology, and oncology. Unlike CT systems, interventional angiographic x-ray systems provide real-time large field of view 2D imaging, patient access, and flexible gantry positioning enabling interventional procedures. However, relative to CT, these C-arm flat panel systems have additional technical challenges in 3D soft tissue imaging including slower rotation speed, gantry vibration, reduced lateral patient field of view (FOV), and increased scatter. The reduced patient FOV often results in significant data truncation. Reconstruction of truncated (incomplete) data is known an "interior problem", and it is mathematically impossible to obtain an exact reconstruction. Nevertheless, it is an important problem in 3D imaging on a C-arm to address the need to generate a 3D reconstruction representative of the object being imaged with minimal artifacts. In this work we investigate the application of an iterative Maximum Likelihood Transmission (MLTR) algorithm to truncated data. We also consider truncated data with limited views for cardiac imaging where the views are gated by the electrocardiogram(ECG) to combat motion artifacts.

  10. AAPM/RSNA physics tutorial for residents: physics of flat-panel fluoroscopy systems: Survey of modern fluoroscopy imaging: flat-panel detectors versus image intensifiers and more.

    PubMed

    Nickoloff, Edward Lee

    2011-01-01

    This article reviews the design and operation of both flat-panel detector (FPD) and image intensifier fluoroscopy systems. The different components of each imaging chain and their functions are explained and compared. FPD systems have multiple advantages such as a smaller size, extended dynamic range, no spatial distortion, and greater stability. However, FPD systems typically have the same spatial resolution for all fields of view (FOVs) and are prone to ghosting. Image intensifier systems have better spatial resolution with the use of smaller FOVs (magnification modes) and tend to be less expensive. However, the spatial resolution of image intensifier systems is limited by the television system to which they are coupled. Moreover, image intensifier systems are degraded by glare, vignetting, spatial distortions, and defocusing effects. FPD systems do not have these problems. Some recent innovations to fluoroscopy systems include automated filtration, pulsed fluoroscopy, automatic positioning, dose-area product meters, and improved automatic dose rate control programs. Operator-selectable features may affect both the patient radiation dose and image quality; these selectable features include dose level setting, the FOV employed, fluoroscopic pulse rates, geometric factors, display software settings, and methods to reduce the imaging time.

  11. Direct-conversion flat-panel imager with avalanche gain: Feasibility investigation for HARP-AMFPI

    SciTech Connect

    Wronski, M. M.; Rowlands, J. A.

    2008-12-15

    The authors are investigating the concept of a direct-conversion flat-panel imager with avalanche gain for low-dose x-ray imaging. It consists of an amorphous selenium (a-Se) photoconductor partitioned into a thick drift region for x-ray-to-charge conversion and a relatively thin region called high-gain avalanche rushing photoconductor (HARP) in which the charge undergoes avalanche multiplication. An active matrix of thin film transistors is used to read out the electronic image. The authors call the proposed imager HARP active matrix flat panel imager (HARP-AMFPI). The key advantages of HARP-AMFPI are its high spatial resolution, owing to the direct-conversion a-Se layer, and its programmable avalanche gain, which can be enabled during low dose fluoroscopy to overcome electronic noise and disabled during high dose radiography to prevent saturation of the detector elements. This article investigates key design considerations for HARP-AMFPI. The effects of electronic noise on the imaging performance of HARP-AMFPI were modeled theoretically and system parameters were optimized for radiography and fluoroscopy. The following imager properties were determined as a function of avalanche gain: (1) the spatial frequency dependent detective quantum efficiency; (2) fill factor; (3) dynamic range and linearity; and (4) gain nonuniformities resulting from electric field strength nonuniformities. The authors results showed that avalanche gains of 5 and 20 enable x-ray quantum noise limited performance throughout the entire exposure range in radiography and fluoroscopy, respectively. It was shown that HARP-AMFPI can provide the required gain while maintaining a 100% effective fill factor and a piecewise dynamic range over five orders of magnitude (10{sup -7}-10{sup -2} R/frame). The authors have also shown that imaging performance is not significantly affected by the following: electric field strength nonuniformities, avalanche noise for x-ray energies above 1 keV and direct

  12. Direct-conversion flat-panel imager with avalanche gain: feasibility investigation for HARP-AMFPI.

    PubMed

    Wronski, M M; Rowlands, J A

    2008-12-01

    The authors are investigating the concept of a direct-conversion flat-panel imager with avalanche gain for low-dose x-ray imaging. It consists of an amorphous selenium (a-Se) photoconductor partitioned into a thick drift region for x-ray-to-charge conversion and a relatively thin region called high-gain avalanche rushing photoconductor (HARP) in which the charge undergoes avalanche multiplication. An active matrix of thin film transistors is used to read out the electronic image. The authors call the proposed imager HARP active matrix flat panel imager (HARP-AMFPI). The key advantages of HARP-AMFPI are its high spatial resolution, owing to the direct-conversion a-Se layer, and its programmable avalanche gain, which can be enabled during low dose fluoroscopy to overcome electronic noise and disabled during high dose radiography to prevent saturation of the detector elements. This article investigates key design considerations for HARP-AMFPI. The effects of electronic noise on the imaging performance of HARP-AMFPI were modeled theoretically and system parameters were optimized for radiography and fluoroscopy. The following imager properties were determined as a function of avalanche gain: (1) the spatial frequency dependent detective quantum efficiency; (2) fill factor; (3) dynamic range and linearity; and (4) gain nonuniformities resulting from electric field strength nonuniformities. The authors results showed that avalanche gains of 5 and 20 enable x-ray quantum noise limited performance throughout the entire exposure range in radiography and fluoroscopy, respectively. It was shown that HARP-AMFPI can provide the required gain while maintaining a 100% effective fill factor and a piecewise dynamic range over five orders of magnitude (10(-7)-10(-2) R/frame). The authors have also shown that imaging performance is not significantly affected by the following: electric field strength nonuniformities, avalanche noise for x-ray energies above 1 keV and direct interaction

  13. A typical flat-panel membrane bioreactor with a composite membrane for sulfur removal

    NASA Astrophysics Data System (ADS)

    Guan, Jian; Xiao, Yuan; Song, Jimin; Miao, Junhe

    2014-03-01

    The aim of this work was to provide a concrete study to understand the effects of operation on biofilm morphology and microstructure and degradation efficiency for the disposal of sulfur dioxide produced by coal-fired power plants. For this purpose, a flat-panel reactor-membrane bioreactor (MBR) with a composite membrane consisting of a dense layer and a support layer was designed; the membrane bioreactors inoculated with Thiobacillus ferrooxidans were further conducted for the removal of sulfur dioxide. Dry weight, active biomass, pressure drop, removal efficiency, morphology and structure of the formed biofilms were investigated and analyzed over period of biofilm formation. The results found that the dry weight, biomass, pressure drops and removal efficiency increased rapidly during biofilm formation, remained relatively stable in the stabilization period of biofilm growth, and finally reached 0.085 g, 7.00 μg, 180 Pa, and 78%, respectively. Our results suggested the MBR is available for flue-gas desulfurization.

  14. Response of laminated composite flat panels to sonic boom and explosive blast loadings

    NASA Technical Reports Server (NTRS)

    Librescu, L.; Nosier, A.

    1990-01-01

    This paper deals with a theoretical analysis of the dynamic response of shear deformable symmetrically laminated rectangular composite flat panels exposed to sonic boom and explosive blast loadings. The pertinent governing equations incorporating transverse shear deformation, transverse normal stress, as well as the higher-order effects are solved by using the integral-transform technique. The obtained results are compared with their counterparts obtained within the framework of the first-order transverse shear deformation and the classical plate theories and some conclusions concerning their range of applicability are outlined. The paper also contains a detailed analysis of the influence played by the various parameters characterizing the considered pressure pulses as well as the material and geometry of the plate.

  15. Method of forming a spacer for field emission flat panel displays

    DOEpatents

    Bernhardt, Anthony F.; Contolini, Robert J.

    1997-01-01

    Spacers for applications such as field emission flat panel displays and vacuum microelectronics, and which involves the application of aerogel/xerogel technology to the formation of the spacer. In a preferred approach the method uses a mold and mold release agent wherein the gel precursor is a liquid which can be applied to the mold filling holes which expose the substrate (either the baseplate or the faceplate). A release agent is applied to the mold prior to precursor application to ease removal of the mold after formation of the dielectric spacer. The shrinkage of the gel during solvent extraction also improves mold removal. The final spacer material is a good dielectric, such as silica, secured to the substrate.

  16. Method of forming a spacer for field emission flat panel displays

    DOEpatents

    Bernhardt, A.F.; Contolini, R.J.

    1997-08-19

    Spacers are disclosed for applications such as field emission flat panel displays and vacuum microelectronics, and which involves the application of aerogel/xerogel technology to the formation of the spacer. In a preferred approach the method uses a mold and mold release agent wherein the gel precursor is a liquid which can be applied to the mold filling holes which expose the substrate (either the baseplate or the faceplate). A release agent is applied to the mold prior to precursor application to ease removal of the mold after formation of the dielectric spacer. The shrinkage of the gel during solvent extraction also improves mold removal. The final spacer material is a good dielectric, such as silica, secured to the substrate. 3 figs.

  17. Combination of CT scanning and fluoroscopy imaging on a flat-panel CT scanner

    NASA Astrophysics Data System (ADS)

    Grasruck, M.; Gupta, R.; Reichardt, B.; Suess, Ch.; Schmidt, B.; Stierstorfer, K.; Popescu, S.; Brady, T.; Flohr, T.

    2006-03-01

    We developed and evaluated a prototype flat-panel detector based Volume CT (fpVCT) scanner. The fpVCT scanner consists of a Varian 4030CB a-Si flat-panel detector mounted in a multi slice CT-gantry (Siemens Medical Solutions). It provides a 25 cm field of view with 18 cm z-coverage at the isocenter. In addition to the standard tomographic scanning, fpVCT allows two new scan modes: (1) fluoroscopic imaging from any arbitrary rotation angle, and (2) continuous, time-resolved tomographic scanning of a dynamically changing viewing volume. Fluoroscopic imaging is feasible by modifying the standard CT gantry so that the imaging chain can be oriented along any user-selected rotation angle. Scanning with a stationary gantry, after it has been oriented, is equivalent to a conventional fluoroscopic examination. This scan mode enables combined use of high-resolution tomography and real-time fluoroscopy with a clinically usable field of view in the z direction. The second scan mode allows continuous observation of a timeevolving process such as perfusion. The gantry can be continuously rotated for up to 80 sec, with the rotation time ranging from 3 to 20 sec, to gather projection images of a dynamic process. The projection data, that provides a temporal log of the viewing volume, is then converted into multiple image stacks that capture the temporal evolution of a dynamic process. Studies using phantoms, ex vivo specimens, and live animals have confirmed that these new scanning modes are clinically usable and offer a unique view of the anatomy and physiology that heretofore has not been feasible using static CT scanning. At the current level of image quality and temporal resolution, several clinical applications such a dynamic angiography, tumor enhancement pattern and vascularity studies, organ perfusion, and interventional applications are in reach.

  18. Quantitative carbon ion beam radiography and tomography with a flat-panel detector.

    PubMed

    Telsemeyer, Julia; Jäkel, Oliver; Martišíková, Mária

    2012-12-07

    High dose gradients are inherent to ion beam therapy. This results in high sensitivity to discrepancies between planned and delivered dose distributions. Therefore an accurate knowledge of the ion stopping power of the traversed tissue is critical. One proposed method to ensure high quality dose deposition is to measure the stopping power by ion radiography. Although the idea of imaging with highly energetic ions is more than forty years old, there is a lack of simple detectors suitable for this purpose. In this study the performance of an amorphous silicon flat-panel detector, originally designed for photon imaging, was investigated for quantitative carbon ion radiography and tomography. The flat-panel detector was exploited to measure the water equivalent thickness (WET) and water equivalent path length (WEPL) of a phantom at the Heidelberg Ion-Beam Therapy Center (HIT). To do so, the ambiguous correlation of detector signal to particle energy was overcome by active or passive variation of carbon ion beam energy and measurement of the signal-to-beam energy correlation. The active method enables one to determine the WET of the imaged object with an uncertainty of 0.5 mm WET. For tomographic WEPL measurements the passive method was exploited resulting in an accuracy of 0.01 WEPL. The developed imaging technique presents a method to measure the two-dimensional maps of WET and WEPL of phantoms with a simple and commercially available detector. High spatial resolution of 0.8 × 0.8 mm(2) is given by the detector design. In the future this powerful tool will be used to evaluate the performance of the treatment planning algorithm by studying WET uncertainties.

  19. Development of next generation digital flat panel catheterization system: design principles and validation methodology

    NASA Astrophysics Data System (ADS)

    Belanger, B.; Betraoui, F.; Dhawale, P.; Gopinath, P.; Tegzes, Pal; Vagvolgyi, B.

    2006-03-01

    The design principles that drove the development of a new cardiovascular x-ray digital flat panel (DFP) detector system are presented, followed by assessments of imaging and dose performance achieved relative to other state of the art FPD systems. The new system (GE Innova 2100 IQ TM) incorporates a new detector with substantially improved DQE at fluoroscopic (73%@1μR) and record (79%@114uR) doses, an x-ray tube with higher continuous fluoro power (3.2kW), a collimator with a wide range of copper spectral filtration (up to 0.9mm), and an improved automatic x-ray exposure management system. The performance of this new system was compared to that of the previous generation GE product (Innova 2000) and to state-of-the art cardiac digital x-ray flat panel systems from two other major manufacturers. Performance was assessed with the industry standard Cardiac X-ray NEMA/SCA and I phantom, and a new moving coronary artery stent (MCAS) phantom, designed to simulate cardiac clinical imaging conditions, composed of an anthropomorphic chest section with stents moving in a manner simulating normal coronary arteries. The NEMA/SCA&I phantom results showed the Innova 2100 IQ to exceed or equal the Innova 2000 in all of the performance categories, while operating at 28% lower dose on average, and to exceed the other DFP systems in most of the performance categories. The MCAS phantom tests showed the Innova 2100 IQ to be significantly better (p << 0.05) than the Innova 2000, and significantly better than the other DFP systems in most cases at comparable or lower doses, thereby verifying excellent performance against design goals.

  20. Cathode Rays in Imaging: From Nipkow Disks to Flat Panel Displays

    NASA Astrophysics Data System (ADS)

    Bardsley, J. Norman

    1997-04-01

    The two essential elements in electronic recording and display of images were discovered before 1897. In 1873 Willoughby Smith and Joseph May, working on the Atlantic telegraph cable, noted that the resistance of selenium changes when light falls on it. In 1884 Paul Nipkow patented a scanning disk, consisting of a flat circular plate with small holes arranged along spiral lines, to be spun between the scene to be scanned and a light sensitive cell. The foundation for the development of more efficient electronic detection of light was laid in the 1880's by the discovery of the photoelectric effect. Meanwhile, in 1879 Crookes had shown that the fluorescence caused by cathode rays on the tube walls could be used to create images through the use of shadow masks. The elucidation of the properties of cathode rays and confirmation that they could be deflected by electrostatic and electromagnetic forces led to the invention by Frederick Braun in 1897 of the cathode ray tube, with its electron gun and fluorescent screen. High resolution television sets capable of displaying moving pictures appeared in laboratories in the 1920's. The cathode ray tube has continued to dominate display technology, but its supremacy is now being challenged by various forms of flat panel displays. The extent to which these new technologies rely on electron dynamics and electron-induced fluorescence will be outlined and the need for further research and development will be discussed. In particular, the ways in which cathode rays are harnessed to produce images in Field-Emission Displays and Plasma Display Panels will be described.

  1. Quantitative analysis of performance of selenium flat-panel detector for interventional mammography

    NASA Astrophysics Data System (ADS)

    Debrie, Anne; Polischuk, Brad T.; Rougeot, Henri; Hansroul, Marc; Poliquin, Eric; Caron, Mario; Wong, Kerwin; Shukri, Ziad; Martin, Jean-Pierre

    2000-04-01

    The purpose of this paper is to analyze the image quality of a selenium-based flat panel detector suited for digital interventional mammography. To characterize the image quality, the DQE was measured at various x-ray exposures. The results indicate that when the detector is quantum noise limited, the DQE is independent of the exposure. A measurement of the quantum detection efficiency of 90% indicates that an electrostatic field shaping effect within the selenium layer gives a greater collection efficiency than that predicted simply by the geometric fill factor of each pixel collection electrode. Measurements were also conducted to determine the relative strength of ghost images on the detector. An image of a high contrast object using an exposure of 183 mR was acquired, followed by a low exposure 6 mR flat field image. No visual indication of a ghost could be found in the latter image even after appropriate windowing and leveling of the image was performed. A subjective comparison of image quality between film/screen and the detector was conducted by acquiring images of the ACR phantom under various exposure conditions. The digital images were printed on film using optimally adjusted LUT's. The resulting images were randomly presented to 15 non-trained observers, who assessed a score for each image. The comparison results show that the image quality obtained with the digital detector is superior to the images acquired with film/screen.

  2. Percutaneous Glycerol Rhizotomy for Trigeminal Neuralgia Using a Single-Plane, Flat Panel Detector Angiography System: Technical Note

    PubMed Central

    ARISHIMA, Hidetaka; KAWAJIRI, Satoshi; ARAI, Hiroshi; HIGASHINO, Yoshifumi; KODERA, Toshiaki; KIKUTA, Ken-ichiro

    2016-01-01

    Percutaneous treatments for trigeminal neuralgia (TN) including glycerol rhizotomy (GR), radiofrequency thermocoagulation (RT), and balloon compression (BC) are effective for patients with medical comorbidities and risk factors of microvascular decompression (MVD). These procedures are usually performed under fluoroscopy. Surgeons advance the needle to the trigeminal plexus through the foramen ovale while observing landmarks of fluoroscopic images; however, it is sometimes difficult to appropriately place the needle tip in Meckel’s cave. We present the technical details of percutaneous GR using a single-plane, flat panel detector angiography system to check the needle positioning. When the needle tip may be located near the trigeminal cistern, three-dimensional (3-D) bone images are taken with cone-beam computed tomography (CT). These images clearly show the position of the needle tip in Meckel’s cave. If it is difficult to place it through the foramen ovale, surgeons perform cone beam CT to observe the actual position of the needle tip at the skull base. After confirming the positional relation between the needle tip and foramen ovale, surgeons can advance it in the precise direction. In 10 procedures, we could place the nerve-block needle in about 14.5 minutes on average without complications. We think that our method is simple and convenient for percutaneous treatments for TN, and it may be helpful for surgeons to perform such treatments. PMID:27041633

  3. Percutaneous Glycerol Rhizotomy for Trigeminal Neuralgia Using a Single-Plane, Flat Panel Detector Angiography System: Technical Note.

    PubMed

    Arishima, Hidetaka; Kawajiri, Satoshi; Arai, Hiroshi; Higashino, Yoshifumi; Kodera, Toshiaki; Kikuta, Ken-Ichiro

    2016-05-15

    Percutaneous treatments for trigeminal neuralgia (TN) including glycerol rhizotomy (GR), radiofrequency thermocoagulation (RT), and balloon compression (BC) are effective for patients with medical comorbidities and risk factors of microvascular decompression (MVD). These procedures are usually performed under fluoroscopy. Surgeons advance the needle to the trigeminal plexus through the foramen ovale while observing landmarks of fluoroscopic images; however, it is sometimes difficult to appropriately place the needle tip in Meckel's cave. We present the technical details of percutaneous GR using a single-plane, flat panel detector angiography system to check the needle positioning. When the needle tip may be located near the trigeminal cistern, three-dimensional (3-D) bone images are taken with cone-beam computed tomography (CT). These images clearly show the position of the needle tip in Meckel's cave. If it is difficult to place it through the foramen ovale, surgeons perform cone beam CT to observe the actual position of the needle tip at the skull base. After confirming the positional relation between the needle tip and foramen ovale, surgeons can advance it in the precise direction. In 10 procedures, we could place the nerve-block needle in about 14.5 minutes on average without complications. We think that our method is simple and convenient for percutaneous treatments for TN, and it may be helpful for surgeons to perform such treatments.

  4. Compact flat-panel gas-gap heat switch operating at 295 K

    NASA Astrophysics Data System (ADS)

    Krielaart, M. A. R.; Vermeer, C. H.; Vanapalli, S.

    2015-11-01

    Heat switches are devices that can change from a thermally conducting (on-) state to an insulating (off-) state whenever the need arises. They enable adaptive thermal management strategies in which cooling rates are altered either spatially or temporally, leading to a substantial reduction in the energy and mass budget of a large range of systems. State-of-the-art heat switches are only rarely employed in thermal system architectures, since they are rather bulky and have a limited thermal performance (expressed as the heat transfer ratio between the on- and off-state heat conductance). Using selective laser melting additive manufacturing technology, also known as 3D printing, we developed a compact flat-panel gas-gap heat switch that offers superior thermal performance, is simpler and more economic to produce and assemble, contains no moving parts, and is more reliable because it lacks welded joints. The manufactured rectangular panel heat switch has frontal device dimensions of 10 cm by 10 cm, thickness of 3.2 mm and weighs just 121 g. An off heat conductance of 0.2 W/K and on-off heat conductance ratio of 38 is observed at 295 K.

  5. Investigation of time-resolved proton radiography using x-ray flat-panel imaging system

    NASA Astrophysics Data System (ADS)

    Jee, K.-W.; Zhang, R.; Bentefour, E. H.; Doolan, P. J.; Cascio, E.; Sharp, G.; Flanz, J.; Lu, H.-M.

    2017-03-01

    Proton beam therapy benefits from the Bragg peak and delivers highly conformal dose distributions. However, the location of the end-of-range is subject to uncertainties related to the accuracy of the relative proton stopping power estimates and thereby the water-equivalent path length (WEPL) along the beam. To remedy the range uncertainty, an in vivo measurement of the WEPL through the patient, i.e. a proton-range radiograph, is highly desirable. Towards that goal, we have explored a novel method of proton radiography based on the time-resolved dose measured by a flat panel imager (FPI). A 226 MeV pencil beam and a custom-designed range modulator wheel (MW) were used to create a time-varying broad beam. The proton imaging technique used exploits this time dependency by looking at the dose rate at the imager as a function of time. This dose rate function (DRF) has a unique time-varying dose pattern at each depth of penetration. A relatively slow rotation of the MW (0.2 revolutions per second) and a fast image acquisition (30 frames per second, ~33 ms sampling) provided a sufficient temporal resolution for each DRF. Along with the high output of the CsI:Tl scintillator, imaging with pixel binning (2  ×  2) generated high signal-to-noise data at a very low radiation dose (~0.1 cGy). Proton radiographs of a head phantom and a Gammex CT calibration phantom were taken with various configurations. The results of the phantom measurements show that the FPI can generate low noise and high spatial resolution proton radiographs. The WEPL values of the CT tissue surrogate inserts show that the measured relative stopping powers are accurate to ~2%. The panel did not show any noticeable radiation damage after the accumulative dose of approximately 3831 cGy. In summary, we have successfully demonstrated a highly practical method of generating proton radiography using an x-ray flat panel imager.

  6. 75 FR 51285 - In the Matter of Certain Flat Panel Digital Televisions and Components Thereof; Notice of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-19

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION In the Matter of Certain Flat Panel Digital Televisions and Components Thereof; Notice of... that information on this matter can be obtained by contacting the Commission's TDD terminal on...

  7. 2D wavelet-analysis-based calibration technique for flat-panel imaging detectors: application in cone beam volume CT

    NASA Astrophysics Data System (ADS)

    Tang, Xiangyang; Ning, Ruola; Yu, Rongfeng; Conover, David L.

    1999-05-01

    The application of the newly developed flat panel x-ray imaging detector in cone beam volume CT has attracted increasing interest recently. Due to an imperfect solid state array manufacturing process, however, defective elements, gain non-uniformity and offset image unavoidably exist in all kinds of flat panel x-ray imaging detectors, which will cause severe streak and ring artifacts in a cone beam reconstruction image and severely degrade image quality. A calibration technique, in which the artifacts resulting from the defective elements, gain non-uniformity and offset image can be reduced significantly, is presented in this paper. The detection of defective elements is distinctively based upon two-dimensional (2D) wavelet analysis. Because of its inherent localizability in recognizing singularities or discontinuities, wavelet analysis possesses the capability of detecting defective elements over a rather large x-ray exposure range, e.g., 20% to approximately 60% of the dynamic range of the detector used. Three-dimensional (3D) images of a low-contrast CT phantom have been reconstructed from projection images acquired by a flat panel x-ray imaging detector with and without calibration process applied. The artifacts caused individually by defective elements, gain non-uniformity and offset image have been separated and investigated in detail, and the correlation with each other have also been exposed explicitly. The investigation is enforced by quantitative analysis of the signal to noise ratio (SNR) and the image uniformity of the cone beam reconstruction image. It has been demonstrated that the ring and streak artifacts resulting from the imperfect performance of a flat panel x-ray imaging detector can be reduced dramatically, and then the image qualities of a cone beam reconstruction image, such as contrast resolution and image uniformity are improved significantly. Furthermore, with little modification, the calibration technique presented here is also applicable

  8. Comparison of ring artifact removal methods using flat panel detector based CT images

    PubMed Central

    2011-01-01

    Background Ring artifacts are the concentric rings superimposed on the tomographic images often caused by the defective and insufficient calibrated detector elements as well as by the damaged scintillator crystals of the flat panel detector. It may be also generated by objects attenuating X-rays very differently in different projection direction. Ring artifact reduction techniques so far reported in the literature can be broadly classified into two groups. One category of the approaches is based on the sinogram processing also known as the pre-processing techniques and the other category of techniques perform processing on the 2-D reconstructed images, recognized as the post-processing techniques in the literature. The strength and weakness of these categories of approaches are yet to be explored from a common platform. Method In this paper, a comparative study of the two categories of ring artifact reduction techniques basically designed for the multi-slice CT instruments is presented from a common platform. For comparison, two representative algorithms from each of the two categories are selected from the published literature. A very recently reported state-of-the-art sinogram domain ring artifact correction method that classifies the ring artifacts according to their strength and then corrects the artifacts using class adaptive correction schemes is also included in this comparative study. The first sinogram domain correction method uses a wavelet based technique to detect the corrupted pixels and then using a simple linear interpolation technique estimates the responses of the bad pixels. The second sinogram based correction method performs all the filtering operations in the transform domain, i.e., in the wavelet and Fourier domain. On the other hand, the two post-processing based correction techniques actually operate on the polar transform domain of the reconstructed CT images. The first method extracts the ring artifact template vector using a homogeneity

  9. JTEC panel report on advanced composites in Japan

    NASA Technical Reports Server (NTRS)

    Diefendorf, R. J.; Grisaffe, S. J.; Hillig, W. B.; Perepezko, J. H.; Pipes, R. B.; Sheehan, J. E.

    1991-01-01

    The JTEC Panel on Advanced Composites visited Japan and surveyed the status and future directions of Japanese high performance ceramic and carbon fibers and their composites in metal, intermetallic, ceramic and carbon matrices. The panel's interests included not only what composite systems were chosen, but also how these systems were developed. A strong carbon and fiber industry makes Japan the leader in carbon fiber technology. Japan has initiated an oxidation resistant carbon/carbon composite program. The goals for this program are ambitious, and it is just starting, but its progress should be closely monitored in the United States.

  10. Application of flat panel OLED display technology for the point-of-care detection of circulating cancer biomarkers

    PubMed Central

    Katchman, Benjamin A.; Smith, Joseph T.; Obahiagbon, Uwadiae; Kesiraju, Sailaja; Lee, Yong-Kyun; O’Brien, Barry; Kaftanoglu, Korhan; Blain Christen, Jennifer; Anderson, Karen S.

    2016-01-01

    Point-of-care molecular diagnostics can provide efficient and cost-effective medical care, and they have the potential to fundamentally change our approach to global health. However, most existing approaches are not scalable to include multiple biomarkers. As a solution, we have combined commercial flat panel OLED display technology with protein microarray technology to enable high-density fluorescent, programmable, multiplexed biorecognition in a compact and disposable configuration with clinical-level sensitivity. Our approach leverages advances in commercial display technology to reduce pre-functionalized biosensor substrate costs to pennies per cm2. Here, we demonstrate quantitative detection of IgG antibodies to multiple viral antigens in patient serum samples with detection limits for human IgG in the 10 pg/mL range. We also demonstrate multiplexed detection of antibodies to the HPV16 proteins E2, E6, and E7, which are circulating biomarkers for cervical as well as head and neck cancers. PMID:27374875

  11. Impact and Penetration of Thin Aluminum 2024 Flat Panels at Oblique Angles of Incidence

    NASA Technical Reports Server (NTRS)

    Ruggeri, Charles R.; Revilock, Duane M.; Pereira, J. Michael; Emmerling, William; Queitzsch, Gilbert K., Jr.

    2015-01-01

    under more extreme conditions, using a projectile with a more complex shape and sharp contacts, impacting flat panels at oblique angles of incidence.

  12. Effect of oblique X-ray incidence in flat-panel computed tomography of the breast.

    PubMed

    Badano, Aldo; Kyprianou, Iacovos S; Freed, Melanie; Jennings, Robert J; Sempau, Josep

    2009-05-01

    We quantify the variation in resolution due to anisotropy caused by oblique X-ray incidence in indirect flat-panel detectors for computed tomography breast imaging systems. We consider a geometry and detector type utilized in breast computed tomography (CT) systems currently being developed. Our methods rely on mantis, a combined X-ray, electron, and optical Monte Carlo transport open source code. The physics models are the most accurate available in general-purpose Monte Carlo packages in the diagnostic energy range. We consider maximum-obliquity angles of 10 ( degrees ) and 13 ( degrees ) at the centers of the 30 and 40 cm detector edges, respectively, and 16 ( degrees ) at the corner of the detector. Our results indicate that blur is asymmetric and that the resolution properties vary significantly with the angle (or location) of incidence. Our results suggest that the asymmetry can be as high as a factor of 2.6 between orthogonal directions. Anisotropy maps predicted by mantis provide an understanding of the effect that such variations have on the imaging system and allow more accurate modeling and optimization of breast CT systems. These maps of anisotropy across the detector could lead to improved reconstruction and help motivate physics-based strategies for computer detection of breast lesions.

  13. Dynamic flat panel detector versus image intensifier in cardiac imaging: dose and image quality.

    PubMed

    Vano, E; Geiger, B; Schreiner, A; Back, C; Beissel, J

    2005-12-07

    The practical aspects of the dosimetric and imaging performance of a digital x-ray system for cardiology procedures were evaluated. The system was configured with an image intensifier (II) and later upgraded to a dynamic flat panel detector (FD). Entrance surface air kerma (ESAK) to phantoms of 16, 20, 24 and 28 cm of polymethyl methacrylate (PMMA) and the image quality of a test object were measured. Images were evaluated directly on the monitor and with numerical methods (noise and signal-to-noise ratio). Information contained in the DICOM header for dosimetry audit purposes was also tested. ESAK values per frame (or kerma rate) for the most commonly used cine and fluoroscopy modes for different PMMA thicknesses and for field sizes of 17 and 23 cm for II, and 20 and 25 cm for FD, produced similar results in the evaluated system with both technologies, ranging between 19 and 589 microGy/frame (cine) and 5 and 95 mGy min(-1) (fluoroscopy). Image quality for these dose settings was better for the FD version. The 'study dosimetric report' is comprehensive, and its numerical content is sufficiently accurate. There is potential in the future to set those systems with dynamic FD to lower doses than are possible in the current II versions, especially for digital cine runs, or to benefit from improved image quality.

  14. Dynamic flat panel detector versus image intensifier in cardiac imaging: dose and image quality

    NASA Astrophysics Data System (ADS)

    Vano, E.; Geiger, B.; Schreiner, A.; Back, C.; Beissel, J.

    2005-12-01

    The practical aspects of the dosimetric and imaging performance of a digital x-ray system for cardiology procedures were evaluated. The system was configured with an image intensifier (II) and later upgraded to a dynamic flat panel detector (FD). Entrance surface air kerma (ESAK) to phantoms of 16, 20, 24 and 28 cm of polymethyl methacrylate (PMMA) and the image quality of a test object were measured. Images were evaluated directly on the monitor and with numerical methods (noise and signal-to-noise ratio). Information contained in the DICOM header for dosimetry audit purposes was also tested. ESAK values per frame (or kerma rate) for the most commonly used cine and fluoroscopy modes for different PMMA thicknesses and for field sizes of 17 and 23 cm for II, and 20 and 25 cm for FD, produced similar results in the evaluated system with both technologies, ranging between 19 and 589 µGy/frame (cine) and 5 and 95 mGy min-1 (fluoroscopy). Image quality for these dose settings was better for the FD version. The 'study dosimetric report' is comprehensive, and its numerical content is sufficiently accurate. There is potential in the future to set those systems with dynamic FD to lower doses than are possible in the current II versions, especially for digital cine runs, or to benefit from improved image quality.

  15. Evaluation of flat panel detector cone beam CT breast imaging with different sizes of breast phantoms

    NASA Astrophysics Data System (ADS)

    Ning, Ruola; Conover, David; Lu, Xianghua; Zhang, Yan; Yu, Yong; Schiffhauer, Linda; Cullinan, Jeanne

    2005-04-01

    The sensitivity to detect small breast cancers and the specificity of conventional mammography (CM) remain limited owing to an overlap in the appearances of lesions and surrounding structure. We propose to address the limitations accompanying CM using flat panel detector (FPD)-based cone beam CT breast imaging (CBCTBI). The purpose of the study is to determine optimal x-ray operation ranges for different sizes of normal breasts and corresponding glandular dose levels. The current CBCT prototype consists of a modified GE HighSpeed Advantage CT gantry, an x-ray tube, a Varian PaxScan 4030CB FPD, a CT table and a PC. Two uncompressed breast phantoms, with the diameters of 10.8 and 13.8 cm, consist of three inserts: a layer of silicone jell simulating a background structure, a lucite plate on which five simulated carcinomas are mounted, and a plate on which six calcifications are attached. With a single scan, 300 projections were acquired for all phantom scans. The optimal x-ray techniques for different phantom sizes were determined. The total mean glandular doses for different size phantoms were measured using a CT pencil ionization chamber. With the optimal x-ray techniques that result in the maximal dose efficiency for the different tissue thickness, the image quality with two different phantoms was evaluated. The results demonstrate that the CBCTBI can detect a few millimeter-size simulated carcinoma and ~ 0.2 mm calcification with clinically acceptable mean glandular doses for different size breasts.

  16. Potential applications of flat-panel volumetric CT in morphologic and functional small animal imaging.

    PubMed

    Greschus, Susanne; Kiessling, Fabian; Lichy, Matthias P; Moll, Jens; Mueller, Margareta M; Savai, Rajkumar; Rose, Frank; Ruppert, Clemens; Günther, Andreas; Luecke, Marcus; Fusenig, Norbert E; Semmler, Wolfhard; Traupe, Horst

    2005-08-01

    Noninvasive radiologic imaging has recently gained considerable interest in basic and preclinical research for monitoring disease progression and therapeutic efficacy. In this report, we introduce flat-panel volumetric computed tomography (fpVCT) as a powerful new tool for noninvasive imaging of different organ systems in preclinical research. The three-dimensional visualization that is achieved by isotropic high-resolution datasets is illustrated for the skeleton, chest, abdominal organs, and brain of mice. The high image quality of chest scans enables the visualization of small lung nodules in an orthotopic lung cancer model and the reliable imaging of therapy side effects such as lung fibrosis. Using contrast-enhanced scans, fpVCT displayed the vascular trees of the brain, liver, and kidney down to the subsegmental level. Functional application of fpVCT in dynamic contrast-enhanced scans of the rat brain delivered physiologically reliable data of perfusion and tissue blood volume. Beyond scanning of small animal models as demonstrated here, fpVCT provides the ability to image animals up to the size of primates.

  17. Temporal-spatial characteristic evaluation in a dynamic flat-panel detector system

    NASA Astrophysics Data System (ADS)

    Kawashima, H.; Tanaka, R.; Matsubara, K.; Ichikawa, K.; Sakuta, K.; Minami, S.; Hayashi, N.; Sanada, S.; Kawamura, M.; Yamamoto, T.

    2010-04-01

    This report presents the fundamental temporospatial characteristics of a dynamic flat-panel detector (FPD) system. We investigated the relationship between pixel value and X-ray pulse output, and examined reproducibility, dependence on pulse width, tube voltage, and pulse rate. Sequential images were obtained using a direct conversion-type dynamic FPD. The exposure conditions were: 110 kV, 80 mA, 6.3 ms, 7.5 fps, source-to-image distance (SID) 1.5 m. X-ray pulse output was measured using a dosimetry system with a sampling interval of 70 μs, to determine temporal changes in each X-ray pulse output. Temporal changes in pixel value were measured in the obtained images, and the relationship between pixel value and X-ray pulse output was examined. Reproducibility was assessed by comparing the results in two sequential images obtained under the same exposure conditions. Moreover, the relationships and properties were evaluated by changing the pulse width (12 ms and 25 ms), tube voltage (80 kV, 90 kV, and 100 kV), and pulse rate (3.75 fps and 15 fps). The results showed a good correlation between the X-ray pulse output and pixel values. Fluctuation of the pixel value measured in sequential images is thought to be mainly due to changes in X-ray pulse output, and is not caused by FPD.

  18. Flat panel detector-based cone beam CT for dynamic imaging: system evaluation

    NASA Astrophysics Data System (ADS)

    Ning, Ruola; Conover, David; Yu, Yong; Zhang, Yan; Cai, Weixing; Yang, Dong; Lu, Xianghua

    2006-03-01

    The purpose of this study is to characterize a newly built flat panel detector (FPD)-based cone beam CT (CBCT) prototype for dynamic imaging. A CBCT prototype has been designed and constructed by completely modifying a GE HiSpeed Advantage (HSA) CT gantry, incorporating a newly acquired large size real-time FPD (Varian PaxScan 4030CB), a new x-ray generator and a dual focal spot angiography x-ray tube that allows the full coverage of the detector. During data acquisition, the x-ray tube and the FPD can be rotated on the gantry over Nx360 degrees due to integrated slip ring technology with the rotation speed of one second/revolution. With a single scan time of up to 40 seconds , multiple sets of reconstructions can be performed for dynamic studies. The upgrade of this system has been completed. The prototype was used for a series of preliminary phantom studies: different sizes of breast phantoms, a Humanoid chest phantom and scatter correction studies. The results of the phantom studies demonstrate that good image quality can be achieved with this newly built prototype.

  19. Breathing chest radiography using a dynamic flat-panel detector combined with computer analysis.

    PubMed

    Tanaka, Rie; Sanada, Shigeru; Suzuki, Masayuki; Kobayashi, Takeshi; Matsui, Takeshi; Inoue, Hitoshi; Yoshihisa, Nakano

    2004-08-01

    Kinetic information is crucial when evaluating certain pulmonary diseases. When a dynamic flat-panel detector (FPD) can be used for a chest examination, kinetic information can be obtained simply and cost-effectively. The purpose of this study was to develop methods for analyzing respiratory kinetics, such as movement of the diaphragm and lung structures, and the respiratory changes in x-ray translucency in local lung fields. Postero-anterior dynamic chest radiographs during respiration were obtained with a modified FPD, which provided dynamic chest radiographs at a rate of 3 frames/s. Image registration for correction of physical motion was followed by measurement of the distance from the lung apex to the diaphragm. Next, we used a cross-correlation technique to measure the vectors of respiratory movement in specific lung areas. Finally, the average pixel value for a given local area was calculated by tracing the same local area in the lung field. This method of analysis was used for six healthy volunteers and one emphysema patient. The results reported here represent the initial stage in the development of a method that may constitute a new method for diagnosing certain pulmonary diseases, such as chronic obstructive pulmonary disease, fibroid lung, and pneumonia. A clinical evaluation of our method is now in progress.

  20. Dynamic chest radiography with a flat-panel detector (FPD): ventilation-perfusion study

    NASA Astrophysics Data System (ADS)

    Tanaka, R.; Sanada, S.; Fujimura, M.; Yasui, M.; Tsuji, S.; Hayashi, N.; Okamoto, H.; Nanbu, Y.; Matsui, O.

    2011-03-01

    Pulmonary ventilation and blood flow are reflected in dynamic chest radiographs as changes in X-ray translucency, i.e., pixel values. This study was performed to investigate the feasibility of ventilation-perfusion (V/Q) study based on the changes in pixel value. Sequential chest radiographs of a patient with ventilation-perfusion mismatch were obtained during respiration using a dynamic flat-panel detector (FPD) system. The lung area was recognized and average pixel value was measured in each area, tracking and deforming the region of interest. Inter-frame differences were then calculated, and the absolute values were summed in each respiratory phase. The results were visualized as ventilation, blood flow, V/Q ratio distribution map and compared to distribution of radioactive counts on ventilation and perfusion scintigrams. In the results, abnormalities were appeared as a reduction of changes in pixel values, and a correlation was observed between the distribution of changes in pixel value and those of radioactivity counts (Ventilation; r=0.78, Perfusion; r=0.77). V/Q mismatch was also indicated as mismatch of changes in pixel value, and a correlation with V/Q calculated by radioactivity counts (r=0.78). These results indicated that the present method is potentially useful for V/Q study as an additional examination in conventional chest radiography.

  1. Quality control phantom for flat panel detector X-ray systems.

    PubMed

    Chida, Koichi; Kaga, Yuji; Haga, Yoshihiro; Takeda, Ken; Zuguchi, Masayuki

    2013-01-01

    X-ray equipment should be routinely checked for optimal imaging performance and appropriate radiation dose. Recently, the use of diagnostic x-ray equipment with flat panel detectors (FPDs) has increased instead of image intensifier (II) and/or screen film systems. In addition, it is necessary to maintain the performance of FPD systems. Unfortunately, no simple quality control (QC) phantom is available for easy evaluation of FPD image performance. This manuscript suggests a novel simple and inexpensive QC phantom for radiography and fluoroscopy. The authors made a new QC phantom for FPD systems to evaluate the spatial resolution, low-contrast resolution, and dynamic range on single (one-shot) x-ray exposures. The phantom consists of three copper thicknesses (0.5, 1.5, and 3.0 mm), an aluminum stepwedge (0.1-2.7 mm), and piano wire of various diameters (0.08-0.5 mm). They also performed an initial check of the new phantom using a FPD system (fluoroscopic and radiographic images). The new phantom is simple and inexpensive to make. This simple phantom is very useful for QC of FPD systems because a visual evaluation of image performance in three thicknesses of copper (low, intermediate, and high attenuation) is readily available with a single exposure. This simple method for daily checking of FPD systems (radiography and fluoroscopy) using the phantom constitutes an easy way to routinely check image performance and will be useful for QC.

  2. Ultra-high resolution flat-panel volume CT: fundamental principles, design architecture, and system characterization.

    PubMed

    Gupta, Rajiv; Grasruck, Michael; Suess, Christoph; Bartling, Soenke H; Schmidt, Bernhard; Stierstorfer, Karl; Popescu, Stefan; Brady, Tom; Flohr, Thomas

    2006-06-01

    Digital flat-panel-based volume CT (VCT) represents a unique design capable of ultra-high spatial resolution, direct volumetric imaging, and dynamic CT scanning. This innovation, when fully developed, has the promise of opening a unique window on human anatomy and physiology. For example, the volumetric coverage offered by this technology enables us to observe the perfusion of an entire organ, such as the brain, liver, or kidney, tomographically (e.g., after a transplant or ischemic event). By virtue of its higher resolution, one can directly visualize the trabecular structure of bone. This paper describes the basic design architecture of VCT. Three key technical challenges, viz., scatter correction, dynamic range extension, and temporal resolution improvement, must be addressed for successful implementation of a VCT scanner. How these issues are solved in a VCT prototype and the modifications necessary to enable ultra-high resolution volumetric scanning are described. The fundamental principles of scatter correction and dose reduction are illustrated with the help of an actual prototype. The image quality metrics of this prototype are characterized and compared with a multi-detector CT (MDCT).

  3. Design and feasibility of active matrix flat panel detector using avalanche amorphous selenium for protein crystallography.

    PubMed

    Sultana, Afrin; Reznik, Alla; Karim, Karim S; Rowlands, J A

    2008-10-01

    Protein crystallography is the most important technique for resolving the three-dimensional atomic structure of protein by measuring the intensity of its x-ray diffraction pattern. This work proposes a large area flat panel detector for protein crystallography based on direct conversion x-ray detection technique using avalanche amorphous selenium (a-Se) as the high gain photoconductor, and active matrix readout using amorphous silicon (a-Si:H) thin film transistors. The detector employs avalanche multiplication phenomenon of a-Se to make the detector sensitive to each incident x ray. The advantages of the proposed detector over the existing imaging plate and charge coupled device detectors are large area, high dynamic range coupled to single x-ray detection capability, fast readout, high spatial resolution, and inexpensive manufacturing process. The optimal detector design parameters (such as detector size, pixel size, and thickness of a-Se layer), and operating parameters (such as electric field across the a-Se layer) are determined based on the requirements for protein crystallography application. The performance of the detector is evaluated in terms of readout time (<1 s), dynamic range (approximately 10(5)), and sensitivity (approximately 1 x-ray photon), thus validating the detector's efficacy for protein crystallography.

  4. Solid-state, flat-panel, digital radiography detectors and their physical imaging characteristics.

    PubMed

    Cowen, A R; Kengyelics, S M; Davies, A G

    2008-05-01

    Solid-state, digital radiography (DR) detectors, designed specifically for standard projection radiography, emerged just before the turn of the millennium. This new generation of digital image detector comprises a thin layer of x-ray absorptive material combined with an electronic active matrix array fabricated in a thin film of hydrogenated amorphous silicon (a-Si:H). DR detectors can offer both efficient (low-dose) x-ray image acquisition plus on-line readout of the latent image as electronic data. To date, solid-state, flat-panel, DR detectors have come in two principal designs, the indirect-conversion (x-ray scintillator-based) and the direct-conversion (x-ray photoconductor-based) types. This review describes the underlying principles and enabling technologies exploited by these designs of detector, and evaluates their physical imaging characteristics, comparing performance both against each other and computed radiography (CR). In standard projection radiography indirect conversion DR detectors currently offer superior physical image quality and dose efficiency compared with direct conversion DR and modern point-scan CR. These conclusions have been confirmed in the findings of clinical evaluations of DR detectors. Future trends in solid-state DR detector technologies are also briefly considered. Salient innovations include WiFi-enabled, portable DR detectors, improvements in x-ray absorber layers and developments in alternative electronic media to a-Si:H.

  5. CRT and flat panel inspection via personal computer-based image processing

    NASA Astrophysics Data System (ADS)

    Melson, John

    1988-12-01

    The light output inspection process of cathode ray tubes, flat panels and other displays often requires extremely precise and time-consuming manual steps. This paper describes the PR-900 Video Photometer, a PC-based photometric, spatial and colorimetric instrument which automates this inspeCtion process - eliminating operator error and greatly reducing measurement time. The PR-900 digitizes the displayed image as acquired in video form and converts the data into an accurate NBS-traceable measurement. The IBM PC/AT-based photometer is designed for speed and resolution. The system includes a personal computer, an image digitizer, a customized CCD-array Video Sensor Assembly (VSA), interwhangeable objective lenses and proprietary VideoView software. Optionally, an automatic VSA Positioning Stage is added for Automatic Test Environment (ATE) applications. With its modular approach, the hardware and software of the video photometer is readily optimized to meet diverse measurement requirements. This versatile instrument is used to calculate such a wide scope of parameters as luminance (brightness) uniformity, line width, luminance profiles, character size, spot contours, modulation transfer function (MTF), misconvergence, geometric distortion and relative chromaticity (color) coordinates.

  6. Planar cone-beam computed tomography with a flat-panel detector

    NASA Astrophysics Data System (ADS)

    Kim, S. H.; Kim, D. W.; Youn, H.; Kim, D.; Kam, S.; Jeon, H.; Kim, H. K.

    2015-12-01

    For a dedicated x-ray inspection of printed-circuit boards (PCBs), a bench-top planar cone-beam computed tomography (pCT) system with a flat-panel detector has been built in the laboratory. The system adopts the tomosynthesis technique that can produce cross-sectional images parallel to the axis of rotation for a limited angular range. For the optimal operation of the system and further improvement in the next design, we have evaluated imaging performances, such as modulation-transfer function, noise-power spectrum, and noise-equivalent number of quanta. The performances are comparatively evaluated with the coventional cone-beam CT (CBCT) acquisition for various scanning angular ranges, applied tube voltages, and geometrical magnification factors. The pCT scan shows a poorer noise performance than the conventional CBCT scan because of less number of projection views used for reconstruction. However, the pCT shows a better spatial-resolution performance than the CBCT. Because the image noise can be compensated by an elevated exposure level during scanning, the pCT can be a useful modality for the PCB inspection that requires higher spatial-resolution performance.

  7. Astaxanthin induction in Microalga H. pluvialis with flat panel airlift photobioreactors under indoor and outdoor conditions.

    PubMed

    Poonkum, Woradej; Powtongsook, Sorawit; Pavasant, Prasert

    2015-01-01

    Astaxanthin was induced from Haematococcus pluvialis (NIES-144) under indoor and outdoor conditions using 17-, 50-, and 90-L flat-panel airlift photobioreactors (FP-APBRs). Preliminary experiments in 1.5-L bubble column photobioreactors (BC-PBRs) revealed that sterilized clean water with 3% CO2 aeration (1.47 cm(3) s(-1) CO2 loading) could best encourage astaxanthin accumulation at 18.21 g m(-3) (3.63% by weight). Operating 17-L FP-APBRs with these bubble column parameters under indoor conditions could further enhance astaxanthin to 26.63 g m(-3) (5.34% by weight). This was potentially due to the inherited up-lift force from the reactor that helped avoid cell precipitation by allowing the cells to be circulated within the reactor. In addition, the various sizes of FP-APBRs exhibited similar performance, implying a potential scale-up opportunity. However, similar operation under outdoor condition exhibited slightly poorer performance due to the light inhibition effect. The best outdoor performance was obtained with the FP-APBR covered with one layer of shading net, where 20.11 g m(-3) (4.47% by weight) of astaxanthin was resulted.

  8. Motion gated small animal imaging with a flat-panel CT

    NASA Astrophysics Data System (ADS)

    Grasruck, M.; Bartling, S.; Dinkel, J.; Kiessling, F.; Semmler, W.; Stierstorfer, K.; Schmidt, B.

    2008-03-01

    Small animal CT gains increasing interest in preclinical research. However, physiological motion compensation like in clinical CT has seldom been employed so far. We present different methods of retrospective motion correction for small animal imaging despite their high respiratory and heart rate. Beside respiratory gating alone the combination of respiratory and simultaneous cardiac gating is shown. In vivo data are acquired with an experimental flat-panel based CT scanner*(Siemens Healthcare, Forchheim Germany). Whole mice or rats fit in the available FOV of 25 * 25 * 4 cm 3, while acquisition rate is 100fps. Extrinsic gating is realized by tracing the physiological motion from a small animal monitoring system with a pneumatic pillow for respiratory motion and ECG for heart motion. At the alternative intrinsic method, the lung motion is directly correlated to the movement of the center of gravity in the acquired projection data. As an advantage of the second method the even low preparation effort per scan is reduced. As long as the rotation time of the gantry is far below the cycle time of heart or the lung a multi-segment reconstruction is used in both methods. Motion artifacts are largely suppressed after gating. While in non gated images, the diaphragm, heart contours, bronchi and lung vessels are already visible, they are more sharply defined in the gated datasets. Four-dimensional assessment of lung motion is possible and lung volume in several phases such as peak inspiration and expiration could be segmented, quantified and compared.

  9. Practical expressions describing detective quantum efficiency in flat-panel detectors

    NASA Astrophysics Data System (ADS)

    Kim, H. K.

    2011-11-01

    In radiology, image quality excellence is a balance between system performance and patient dose, hence x-ray systems must be designed to ensure the maximum image quality is obtained for the lowest consistent dose. The concept of detective quantum efficiency (DQE) is widely used to quantify, understand, measure, and predict the performance of x-ray detectors and imaging systems. Cascaded linear-systems theory can be used to estimate DQE based on the system design parameters and this theoretical DQE can be utilized for determining the impact of various physical processes, such as secondary quantum sinks, noise aliasing, reabsorption noise, and others. However, the prediction of DQE usually requires tremendous efforts to determine each parameter consisting of the cascaded linear-systems model. In this paper, practical DQE formalisms assessing both the photoconductor- and scintillator-based flat-panel detectors under quantum-noise-limited operation are described. The developed formalisms are experimentally validated and discussed for their limits. The formalisms described in this paper would be helpful for the rapid prediction of the DQE performances of developing systems as well as the optimal design of systems.

  10. Performance of cone-beam CT using a flat-panel imager

    NASA Astrophysics Data System (ADS)

    Endo, Masahiro; Tsunoo, Takanori; Satoh, Kazumasa; Matsusita, Satoshi; Kusakabe, Masahiro; Fukuda, Yasushi

    2001-06-01

    An active matrix flat-panel imager (FPI) is a good candidate for the 2-dimensional detector of cone beam CT (CBCT), because it has a wider dynamic range and less geometrical distortion than video-fluoroscopic system so far employed. However the performance of FPI-based CBCT has not been sufficiently examined yet. The aim of this work is to examine the performance of CBCT using a FPI with several phantoms. An X-ray tube, a phantom and a FPI were aligned on an experimental table. The FPI was PaxScan2520 provided by Varian Medical Systems. It has an active area of approximately 180x240mm and the pixel size is 127 micrometer. CsI is used as a scintillator. The phantom was rotated with 1-degree steps while 360 projection frames (1408x1888 active pixels each frame) were collected. 2x2 pixels were combined into a single pixel to reduce noise. 512x512x512 voxels were reconstructed with the Feldkamp method. The comparison was made between reconstructed images with or without scatter rejecting grid. The uniformity and linearity of reconstruction value was drastically improved with the grid. Scatter rejection using a thin-vane collimator was also examined, and it showed more effective than the grid.

  11. [Physical imaging properties of a flat panel X-ray detector system].

    PubMed

    Yoshida, Akira; Nakamura, Satoru; Nishihara, Sadamitsu; Kohama, Chiyuki; Takahata, Akira; Fujikawa, Kouichi

    2002-01-01

    We report the physical imaging properties of a flat panel detector (FPD) designed for radiographic imaging applications (Revolution XQ/i digital chest imaging system, G.E. Medical Systems). The imaging properties of the detector were evaluated through measurements of the characteristic curve, modulation transfer function (MTF), and Wiener spectrum. The digital characteristic curves of the FPD system were measured for the two tube voltages (80 kV and 120 kV). They showed that the correlation between the pixel values of FPD and the incident exposure to the FPD was a linear correlation. The dynamic range of characteristic curves had a range from about 0.003 to 2 microC/kg at the exposure. The presampling MTFs for different tube voltage were almost the same, when we measured the MTFs at 80 kV and 120 kV. And also, there was no significant difference between the MTFs measured with the slit in the direction parallel to the horizontal direction and with the slit in the perpendicular direction. The relative resolution of the FPD system was a 46% higher than that of ST-V imaging plate of FCR (Fuji Computed Radiography) system at 2 cycles/mm. The digital Wiener spectrum of the FPD system was about 1/10 lower than that of the CR system. Thus the FPD system can provide superior imaging performance due to both high resolution and low noise.

  12. [Reproducibility of dynamic chest radiography with a flat-panel detector - respiratory changes in pixel value].

    PubMed

    Kawashima, Hiroki; Tanaka, Rie; Sanada, Shigeru

    2009-06-20

    Dynamic chest radiography using a flat panel detector (FPD) with a large field of view is expected to be a useful pulmonary functional evaluation method based on the respiratory changes in pixel value. For clinical use as a follow-up and therapeutic evaluation tool, the system must have a high degree of reproducibility in measurements of pixel values. The present study was performed to investigate the reproducibility of respiratory changes in pixel values. Dynamic chest radiographs of five normal subjects and one patient were obtained. Imaging was performed twice in each subject. The slope (X-ray translucency variation) was then calculated from the changes in pixel value from distance lung apex-diaphragm, and the slopes of two sequences were compared. The results showed there were no significant differences in changes in pixel value between the two sequences in all normal subject (5 males, p>0.05). The results indicated that the present method has reproducibility for measuring pulmonary function and also has potential as a tool for follow-up and therapeutic evaluation.

  13. Continuous production of diatom Entomoneis sp. in mechanically stirred tank and flat-panel airlift photobioreactors.

    PubMed

    Viriyayingsiri, Thunyaporn; Sittplangkoon, Pantaporn; Powtongsook, Sorawit; Nootong, Kasidit

    2016-10-02

    Continuous production of diatom Entomonies sp. was performed in mechanically stirred tank and flat-panel airlift photobioreactors (FPAP). The maximum specific growth rate of diatom from the batch experiment was 0.98 d(-1). A series of dilution rate and macronutrient concentration adjustments were performed in a stirred tank photobioreactor and found that the dilution rate ranged from 0.7 to 0.8 d(-1) and modified F/2 growth media containing nitrate at 3.09 mg N/L, phosphate at 2.24 mg P/L, and silicate at 11.91 mg Si/L yielded the maximum cell number density. Finally, the continuous cultivation of Entomonies sp. was conducted in FPAP using the optimal conditions determined earlier, resulting in the maximum cell number density of 19.69 × 10(4) cells/mL, which was approximately 47 and 73% increase from the result using the stirred tank photobioreactor fed with modified and standard F/2 growth media, respectively.

  14. Crystallization of silicon films on glass: a comparison of methods. [Flat panel displays

    SciTech Connect

    Lemons, R.A.; Bosch, M.A.; Herbst, D.

    1982-01-01

    The lure of flat panel displays has stimulated much research on the crystallization of silicon films deposited on large-area transparent substrates. In most respects, fused quartz is ideal. It has high purity, thermal shock resistance, and a softening point above the silicon melting temperature. Unfortunately, fused quartz has such a small thermal expansion that the silicon film cracks as it cools. This problem has been attacked by patterning with islands or moats before and after crystallization, by capping, and by using silicate glass substrates that match the thermal expansion of silicon. The relative merits of these methods are compared. Melting of the silicon film to achieve high mobility has been accomplished by a variety of methods including lasers, electron beams, and strip heaters. For low melting temperature glasses, surface heating with a laser or electron beam is essential. Larger grains are obtained with the high bias temperature, strip heater techniques. The low-angle grain boundaries characteristic of these films may be caused by constitutional undercooling. A model is developed to predict the boundary spacing as a function of scan rate and temperature gradient. 11 figures.

  15. A forward bias method for lag correction of an a-Si flat panel detector

    SciTech Connect

    Starman, Jared; Tognina, Carlo; Partain, Larry; Fahrig, Rebecca

    2012-01-15

    Purpose: Digital a-Si flat panel (FP) x-ray detectors can exhibit detector lag, or residual signal, of several percent that can cause ghosting in projection images or severe shading artifacts, known as the radar artifact, in cone-beam computed tomography (CBCT) reconstructions. A major contributor to detector lag is believed to be defect states, or traps, in the a-Si layer of the FP. Software methods to characterize and correct for the detector lag exist, but they may make assumptions such as system linearity and time invariance, which may not be true. The purpose of this work is to investigate a new hardware based method to reduce lag in an a-Si FP and to evaluate its effectiveness at removing shading artifacts in CBCT reconstructions. The feasibility of a novel, partially hardware based solution is also examined. Methods: The proposed hardware solution for lag reduction requires only a minor change to the FP. For pulsed irradiation, the proposed method inserts a new operation step between the readout and data collection stages. During this new stage the photodiode is operated in a forward bias mode, which fills the defect states with charge. A Varian 4030CB panel was modified to allow for operation in the forward bias mode. The contrast of residual lag ghosts was measured for lag frames 2 and 100 after irradiation ceased for standard and forward bias modes. Detector step response, lag, SNR, modulation transfer function (MTF), and detective quantum efficiency (DQE) measurements were made with standard and forward bias firmware. CBCT data of pelvic and head phantoms were also collected. Results: Overall, the 2nd and 100th detector lag frame residual signals were reduced 70%-88% using the new method. SNR, MTF, and DQE measurements show a small decrease in collected signal and a small increase in noise. The forward bias hardware successfully reduced the radar artifact in the CBCT reconstruction of the pelvic and head phantoms by 48%-81%. Conclusions: Overall, the

  16. SAPHIRE: A New Flat-Panel Digital Mammography Detector With Avalanche Photoconductor and High-Resolution Field Emitter Readout

    DTIC Science & Technology

    2006-06-01

    array of TFTs, simi- lar to that in existing AMFPI. The proposed detector is named SHARP-AMFPI scintillator-HARP active matrix flat-panel imager...the wavelength of the incident photon. It was found by Pai and Enck that the ESe and dependence of photogeneration in a-Se follow the Onsager ...mechanism.25 Onsager theory states that every absorbed photon creates a pair of thermalized carriers bound by their Coulombic attrac- tion. The initial

  17. A flat-panel detector based micro-CT system: performance evaluation for small-animal imaging

    NASA Astrophysics Data System (ADS)

    Lee, Sang Chul; Kim, Ho Kyung; Chun, In Kon; Hye Cho, Myung; Lee, Soo Yeol; Cho, Min Hyoung

    2003-12-01

    A dedicated small-animal x-ray micro computed tomography (micro-CT) system has been developed to screen laboratory small animals such as mice and rats. The micro-CT system consists of an indirect-detection flat-panel x-ray detector with a field-of-view of 120 × 120 mm2, a microfocus x-ray source, a rotational subject holder and a parallel data processing system. The flat-panel detector is based on a matrix-addressed photodiode array fabricated by a CMOS (complementary metal-oxide semiconductor) process coupled to a CsI:Tl (thallium-doped caesium iodide) scintillator as an x-ray-to-light converter. Principal imaging performances of the micro-CT system have been evaluated in terms of image uniformity, voxel noise and spatial resolution. It has been found that the image non-uniformity mainly comes from the structural non-uniform sensitivity pattern of the flat-panel detector and the voxel noise is about 48 CT numbers at the voxel size of 100 × 100 × 200 µm3 and the air kerma of 286 mGy. When the magnification ratio is 2, the spatial resolution of the micro-CT system is about 14 lp/mm (line pairs per millimetre) that is almost determined by the flat-panel detector showing about 7 lp/mm resolving power. Through low-contrast phantom imaging studies, the minimum resolvable contrast has been found to be less than 36 CT numbers at the air kerma of 95 mGy. Some laboratory rat imaging results are presented.

  18. 76 FR 45296 - In the Matter of Certain Flat Panel Display Devices, and Products Containing the Same; Notice of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-28

    ... sale for importation, and the sale within the United States after importation of certain flat panel.... Patent No. 6,281,955 (``the `955 patent''); U.S. Patent No. 7,697,093 (``the `093 patent''); U.S. Patent No. 7,286,192 (``the `192 patent''); U.S. Patent No. 6,818,967 (``the `967 patent''); U.S. Patent...

  19. Assessment of the CO2 fixation capacity of Anabaena sp. ATCC 33047 outdoor cultures in vertical flat-panel reactors.

    PubMed

    Clares, Marta E; Moreno, José; Guerrero, Miguel G; García-González, Mercedes

    2014-10-10

    The extent of biological CO2 fixation was evaluated for outdoor cultures of the cyanobacterium Anabaena sp. ATCC 33047. Culture conditions were optimized indoors in bubble-column photochemostats operating in continuous mode, subjected to irradiance cycles mimicking the light regime outdoors. Highest values achieved for CO2 fixation rate and biomass productivity were 1 and 0.6 g L(-1) day(-1), respectively. The comparison among different reactors operating simultaneously - open pond, horizontal tubular reactor and vertical flat-panel - allowed to assess their relative efficiency for the outdoor development of Anabaena cultures. Despite the higher volumetric CO2 fixation capacity (and biomass productivity) exhibited by the tubular photobioreactor, yield of the flat-panel reactor was 50% higher than that of the tubular option on a per area basis, reaching values over 35 g CO2 fixed m(-2) d(-1). The flat-panel reactor actually represents a most suitable system for CO2 capture coupled to the generation of valuable biomass by Anabaena cultures.

  20. Indirect flat-panel detector with avalanche gain: design and operation of the avalanche photoconductor

    NASA Astrophysics Data System (ADS)

    Zhao, Wei; Li, Dan; Reznik, Alla; Lui, Brian; Hunt, D. C.; Tanioka, Kenkichi; Rowlands, J. A.

    2005-04-01

    An indirect flat-panel imager (FPI) with avalanche gain is being investigated for low-dose x-ray imaging. It is made by optically coupling a structured x-ray scintillator CsI(Tl) to an amorphous selenium (a-Se) avalanche photoconductor called HARP. The final electronic image can be read out using either an array of thin film transistors (TFT) or field emitters (FE). The advantage of the proposed detector is its programmable gain, which can be turned on during low dose fluoroscopy to overcome electronic noise, and turned off during high dose radiography to avoid pixel saturation. This paper investigates the important design considerations for HARP such as avalanche gain, which depends on both the thickness dSe and the applied electric field ESe. To determine the optimal design parameter and operational conditions for HARP, we measured the ESe dependence of both avalanche gain and optical quantum efficiency of an 8 μm HARP layer. The results were applied to a physical model of HARP as well as a linear cascaded model of the FPI to determine the following x-ray imaging properties in both the avalanche and non-avalanche modes as a function of ESe: (1) total gain (which is the product of avalanche gain and optical quantum efficiency); (2) linearity; (3) dynamic range; and (4) gain non-uniformity resulting from thickness non-uniformity. Our results showed that a HARP layer thickness of 8 μm can provide adequate avalanche gain and sufficient dynamic range for x-ray imaging applications to permit quantum limited operation over the range of exposures needed for radiography and fluoroscopy.

  1. Flat panel detector-based cone-beam volume CT angiography imaging: system evaluation.

    PubMed

    Ning, R; Chen, B; Yu, R; Conover, D; Tang, X; Ning, Y

    2000-09-01

    Preliminary evaluation of recently developed large-area flat panel detectors (FPDs) indicates that FPDs have some potential advantages: compactness, absence of geometric distortion and veiling glare with the benefits of high resolution, high detective quantum efficiency (DQE), high frame rate and high dynamic range, small image lag (< 1%), and excellent linearity (approximately 1%). The advantages of the new FPD make it a promising candidate for cone-beam volume computed tomography (CT) angiography (CBVCTA) imaging. The purpose of this study is to characterize a prototype FPD-based imaging system for CBVCTA applications. A prototype FPD-based CBVCTA imaging system has been designed and constructed around a modified GE 8800 CT scanner. This system is evaluated for a CBVCTA imaging task in the head and neck using four phantoms and a frozen rat. The system is first characterized in terms of linearity and dynamic range of the detector. Then, the optimal selection of kVps for CBVCTA is determined and the effect of image lag and scatter on the image quality of the CBVCTA system is evaluated. Next, low-contrast resolution and high-contrast spatial resolution are measured. Finally, the example reconstruction images of a frozen rat are presented. The results indicate that the FPD-based CBVCT can achieve 2.75-lp/mm spatial resolution at 0% modulation transfer function (MTF) and provide more than enough low-contrast resolution for intravenous CBVCTA imaging in the head and neck with clinically acceptable entrance exposure level. The results also suggest that to use an FPD for large cone-angle applications, such as body angiography, further investigations are required.

  2. Flat-panel volumetric computed tomography in cerebral perfusion: evaluation of three rat stroke models.

    PubMed

    Juenemann, Martin; Goegel, Sinja; Obert, Martin; Schleicher, Nadine; Ritschel, Nouha; Doenges, Simone; Eitenmueller, Inka; Schwarz, Niko; Kastaun, Sabrina; Yeniguen, Mesut; Tschernatsch, Marlene; Gerriets, Tibo

    2013-09-30

    Flat-panel volumetric computed tomography (fpVCT) is a non-invasive approach to three-dimensional small animal imaging. The capability of volumetric scanning and a high resolution in time and space enables whole organ perfusion studies. We aimed to assess feasibility and validity of fpVCT in cerebral perfusion measurement with impaired hemodynamics by evaluation of three well-established rat stroke models for temporary and permanent middle cerebral artery occlusion (MCAO). Male Wistar rats were randomly assigned to temporary (group I: suture model) and permanent (group II: suture model; III: macrosphere model) MCAO and to a control group. Perfusion scans with respect to cerebral blood flow (CBF) and volume (CBV) were performed 24h post intervention by fpVCT, using a Gantry rotation time of 1s and a total scanning time of 30s. Postmortem analysis included infarct-size calculation by 2,3,5-triphenyltetrazolium chloride (TTC) staining. Infarct volumes did not differ significantly throughout intervention groups. After permanent MCAO, CBF significantly decreased in subcortical regions to 78.2% (group II, p=0.005) and 79.9% (group III, p=0.012) and in total hemisphere to 77.4% (group II, p=0.010) and 82.0% (group III, p=0.049). CBF was less impaired with temporary vessel occlusion. CBV measurement revealed no significant differences. Results demonstrate feasibility of cerebral perfusion quantification in rats with the fpVCT, which can be a useful tool for non-invasive dynamic imaging of cerebral perfusion in rodent stroke models. In addition to methodological advantages, CBF data confirm the macrosphere model as a useful alternative to the suture model for permanent experimental MCAO.

  3. Performance of a direct-detection active matrix flat panel dosimeter (AMFPD) for IMRT measurements.

    PubMed

    Chen, Yu; Moran, Jean M; Roberts, Donald A; El-Mohri, Youcef; Antonuk, Larry E; Fraass, Benedick A

    2007-12-01

    The dosimetric performance of a direct-detection active matrix flat panel dosimeter (AMFPD) is reported for intensity modulated radiation therapy (IMRT) measurements. The AMFPD consists of a-Si : H photodiodes and thin-film transistors deposited on a glass substrate with no overlying scintillator screen or metal plate. The device is operated at 0.8 frames per second in a continuous acquisition or fluoroscopic mode. The effect of the applied bias voltage across the photodiodes on the response of the AMFPD was evaluated because this parameter affects dark signal, lag contributions, and pixel sensitivity. In addition, the AMPFD response was evaluated as a function of dose, dose rate, and energy, for static fields at 10 cm depth. In continuous acquisition mode, the AMFPD maintained a linear dose response (r2 > 0.99999) up to at least 1040 cGy. In order to obtain reliable integrated dose results for IMRT fields, the effects of lag on the radiation signal were minimized by operating the system at the highest frame rate and at an appropriate reverse bias voltage. Segmental MLC and dynamic MLC IMRT fields were measured with the AMFPD, and the results were compared to film, using standard methods for reliable film dosimetry. Both AMFPD and film measurements were independently converted to dose in cGy. Gamma and chi values were calculated as indices of agreement. The results from the AMFPD were in excellent agreement with those from film. When 2% of D(max) and 2 mm of distance to agreement were used as the criteria, 98% of the region of interest (defined as the region where dose is greater than 5% of D(max)) satisfied [chi] < or = 1 on average across the cases that were tested.

  4. Influence of Flat-Panel Fluoroscopic Equipment Variables on Cardiac Radiation Doses

    SciTech Connect

    Nickoloff, Edward L. Lu Zhengfeng; Dutta, Ajoy; So, James; Balter, Stephen; Moses, Jeffrey

    2007-04-15

    Purpose. To assess the influence of physician-selectable equipment variables on the potential radiation dose reductions during cardiac catheterization examinations using modern imaging equipment. Materials. A modern bi-plane angiography unit with flat-panel image receptors was used. Patients were simulated with 15-30 cm of acrylic plastic. The variables studied were: patient thickness, fluoroscopy pulse rates, record mode frame rates, image receptor field-of-view (FoV), automatic dose control (ADC) mode, SID/SSD geometry setting, automatic collimation, automatic positioning, and others. Results. Patient radiation doses double for every additional 3.5-4.5 cm of soft tissue. The dose is directly related to the imaging frame rate; a decrease from 30 pps to 15 pps reduces the dose by about 50%. The dose is related to [(FoV){sup -N}] where 2.0 < N < 3.0. Suboptimal positioning of the patient can nearly double the dose. The ADC system provides three selections that can vary the radiation level by 50%. For pediatric studies (2-5 years old), the selection of equipment variables can result in entrance radiation doses that range between 6 and 60 cGy for diagnostic cases and between 15 and 140 cGy for interventional cases. For adult studies, the equipment variables can produce entrance radiation doses that range between 13 and 130 cGy for diagnostic cases and between 30 and 400 cGy for interventional cases. Conclusions. Overall dose reductions of 70-90% can be achieved with pediatric patients and about 90% with adult patients solely through optimal selection of equipment variables.

  5. Do LCDs have a chance to keep a leading position on flat panel display market?

    NASA Astrophysics Data System (ADS)

    Zielinski, Jerzy; Olifierczuk, Marek

    2004-09-01

    A lot of significant discoveries and inventions in the field of technology of displays were made in the latter part of the twentieth century. Apart from well-known CRT, the plasma-, luminescence- and liquid crystal-displays are commercially available. One can notice that a leading position on that flat panel displays market belong to LCD. But the progress in Organic LED materials and devices is impressive. Threshold voltage for light emission have fallen from several thousands V to just 2 - 3 V for today's OLEDs (polymer and small molecule). Luminous efficiency has increased from 0,01 to more than 10 lm/W. These improvements have brought PLED technology to the point where serious consideration is being given to OLED graphic and video display product. The question given some years ago by Dr. M. E. Becker, [Display Metrology and Systems]: "...is the current OLED enthusiasm justified because OLED displays feature significant improvements in visual and ergonomic performance, and because they are much cheaper to manufacture; Or it is just another hope for those who missed the LCD train?...," is trite. During SID Conference in Baltimore in 2003 two companies claiming to have built the largest organic LED. International Display Technology demonstrated a 20 inch display driven by "super amorphous silicon" technology; Sony showed off its 24 inch screen, which consists of a 2x2 tiled array of OLED displays. The presented work will be oriented towards specifying the characteristic features of liquid crystal and electro luminescence organic compounds which make these groups of displays so attractive and prospective among other imagery systems devices existing nowadays.

  6. Evaluation of the potential utility of flat panel CT for quantifying relative contrast enhancement

    SciTech Connect

    Jones, A. Kyle; Mahvash, Armeen

    2012-07-15

    Purpose: Certain directed oncologic therapies seek to take advantage of the fact that tumors are typically more susceptible to directed therapeutic agents than normal tissue owing to their extensive networks of poorly formed, leaky vasculature. If differences between the vascularity of normal and tumor tissues could be quantified, patients could be selected for or excluded from directed treatments on the basis of this difference. However, angiographic imaging techniques such as digital subtraction angiography (DSA) yield two-dimensional data that may be inadequate for this task. As a first step, the authors evaluated the feasibility of using a commercial implementation of flat panel computed tomography (FPCT) to quantify differences in enhancement of a simulated tumor compared with normal tissue based on differences in CT number measured in precontrast and postcontrast scans. Methods: To evaluate the FPCT scanner studied, the authors scanned several phantoms containing simulated normal and tumor tissues. In the first experiment, the authors used an anthropomorphic phantom containing inclusions representing normal, tumor, and bone tissue to evaluate the constancy of CT numbers in scans repeated at clinically relevant intervals of 1 and 3 min. The authors then scanned gelatin phantoms containing dilutions of iodinated contrast to evaluate the accuracy of relative contrast enhancement measurements for a clinical FPCT system. Data were analyzed using widely available software. Results: CT numbers measured in identical locations were constant over both scan intervals evaluated. Measured relative contrast enhancement values were accurate compared with known relative contrast enhancement values. Care must be taken to avoid artifacts in reconstructed images when placing regions of interest. Conclusions: Despite its limitations, FPCT in the interventional laboratory can be used to quantify relative contrast enhancement in phantoms. This is accomplished by measuring CT

  7. Image quality assessment of a pre-clinical flat-panel volumetric micro-CT scanner

    NASA Astrophysics Data System (ADS)

    Du, Louise Y.; Lee, Ting-Yim; Holdsworth, David W.

    2006-03-01

    Small animal imaging has recently become an area of increased interest because more human diseases can be modeled in transgenic and knockout rodents. Current micro-CT systems are capable of achieving spatial resolution on the order of 10 μm, giving highly detailed anatomical information. However, the speed of data acquisition of these systems is relatively slow, when compared with clinical CT systems. Dynamic CT perfusion imaging has proven to be a powerful tool clinically in detecting and diagnosing cancer, stroke, pulmonary and ischemic heart diseases. In order to perform this technique in mice and rats, quantitative CT images must be acquired at a rate of at least 1 Hz. Recently, a research pre-clinical CT scanner (eXplore Ultra, GE Healthcare) has been designed specifically for dynamic perfusion imaging in small animals. Using an amorphous silicon flat-panel detector and a clinical slip-ring gantry, this system is capable of acquiring volumetric image data at a rate of 1 Hz, with in-plane resolution of 150 μm, while covering the entire thoracic region of a mouse or whole organs of a rat. The purpose of this study was to evaluate the principal imaging performance of the micro-CT system, in terms of spatial resolution, image uniformity, linearity, dose and voxel noise for the feasibility of imaging mice and rats. Our investigations show that 3D images can be obtained with a limiting spatial resolution of 2.7 line pairs per mm and noise of 42 HU, using an acquisition interval of 8 seconds at an entrance dose of 6.4 cGy.

  8. The effect of discontinuous airlift mixing in outdoor flat panel photobioreactors on growth of Scenedesmus obliquus.

    PubMed

    Leupold, Marco; Hindersin, Stefan; Kerner, Martin; Hanelt, Dieter

    2013-11-01

    Discontinuous airlift mixing was realized by injecting pressured air at time intervals with a frequency between 0.033 and 0.25 Hz (at 80 kPa; i.e., every 4-30 s; valve opening time 800 ms) into outdoor flat panel photobioreactors ([Formula: see text]). This caused a flow velocity between 2 and 20 cm s(-1) of the culture medium within the photobioreactor and the mixing time was between 38 and 103.5 s, requiring 0.175-1.340 L(gas volume) L(photobioreactor volume)(-1) min(-1) pressured air. In order to detect the effect on growth of Scenedesmus obliquus during outdoor experiments and to be able to compare obtained results, a batch run with an airlift frequency of 0.25 Hz was simultaneously used as control. Growth at different airlift frequencies was measured by the increase of cell dry weight (CDW) during 3-5 days and biomass yield on light energy was calculated. With increasing airlift frequencies, growth increased from 52 to 91 % compared to the control. When CDW was at around 1.0-1.5 g L(-1), airlift frequency had no effect on growth, indicating that mass transfer gradients of nutrients and gas were not the limiting factors of growth. Above 1.5 g CDW L(-1), growth increased with increasing airlift frequency and light limitation for a single cell occurred. This effect was observed during low and high irradiance and it is concluded that a higher mean flow causes a better light distribution, resulting in an enhanced growth. Biomass productivity and demand of pressured air are correlated logarithmically, which enables to save mixing energy during cultivation.

  9. Relative dosimetry using active matrix flat-panel imager (AMFPI) technology.

    PubMed

    El-Mohri, Y; Antonuk, L E; Yorkston, J; Jee, K W; Maolinbay, M; Lam, K L; Siewerdsen, J H

    1999-08-01

    The first examination of the use of active matrix flat-panel arrays for dosimetry in radiotherapy is reported. Such arrays are under widespread development for diagnostic and radiotherapy imaging. In the current study, an array consisting of 512 x 512 pixels with a pixel pitch of 508 microm giving an area of 26 x 26 cm2 has been used. Each pixel consists of a light sensitive amorphous silicon (a-Si:H) photodiode coupled to an a-Si:H thin-film transistor. Data was obtained from the array using a dedicated electronics system allowing real-time data acquisition. In order to examine the potential of such arrays as quality assurance devices for radiotherapy beams, field profile data at photon energies of 6 and 15 MV were obtained as a function of field size and thickness of overlying absorbing material (solid water). Two detection configurations using the array were considered: a configuration (similar to the imaging configuration) in which an overlying phosphor screen is used to convert incident radiation to visible light photons which are detected by the photodiodes; and a configuration without the screen where radiation is directly sensed by the photodiodes. Compared to relative dosimetry data obtained with an ion chamber, data taken using the former configuration exhibited significant differences whereas data obtained using the latter configuration was generally found to be in close agreement. Basic signal properties, which are pertinent to dosimetry, have been investigated through measurements of individual pixel response for fluoroscopic and radiographic array operation. For signal levels acquired within the first 25% of pixel charge capacity, the degree of linear response with dose was found to be better than 99%. The independence of signal on dose rate was demonstrated by means of stability of pixel response over the range of dose rates allowed by the radiation source (80-400 MU/min). Finally, excellent long-term stability in pixel response, extending over a 2

  10. Multidetector-row CT with a 64-row amorphous silicon flat panel detector

    NASA Astrophysics Data System (ADS)

    Shapiro, Edward G.; Colbeth, Richard E.; Daley, Earl T.; Job, Isaias D.; Mollov, Ivan P.; Mollov, Todor I.; Pavkovich, John M.; Roos, Pieter G.; Star-Lack, Josh M.; Tognina, Carlo A.

    2007-03-01

    A unique 64-row flat panel (FP) detector has been developed for sub-second multidetector-row CT (MDCT). The intent was to explore the image quality achievable with relatively inexpensive amorphous silicon (a-Si) compared to existing diagnostic scanners with discrete crystalline diode detectors. The FP MDCT system is a bench-top design that consists of three FP modules. Each module uses a 30 cm x 3.3 cm a-Si array with 576 x 64 photodiodes. The photodiodes are 0.52 mm x 0.52 mm, which allows for about twice the spatial resolution of most commercial MDCT scanners. The modules are arranged in an overlapping geometry, which is sufficient to provide a full-fan 48 cm diameter scan. Scans were obtained with various detachable scintillators, e.g. ceramic Gd IIO IIS, particle-in-binder Gd IIO IIS:Tb and columnar CsI:Tl. Scan quality was evaluated with a Catphan-500 performance phantom and anthropomorphic phantoms. The FP MDCT scans demonstrate nearly equivalent performance scans to a commercial 16-slice MDCT scanner at comparable 10 - 20 mGy/100mAs doses. Thus far, a high contrast resolution of 15 lp/cm and a low contrast resolution of 5 mm @ 0.3 % have been achieved on 1 second scans. Sub-second scans have been achieved with partial rotations. Since the future direction of MDCT appears to be in acquiring single organ coverage per scan, future efforts are planned for increasing the number of detector rows beyond the current 64- rows.

  11. Functional shoulder radiography with use of a dynamic flat panel detector.

    PubMed

    Sakuda, Keita; Sanada, Shigeru; Tanaka, Rie; Kitaoka, Katsuhiko; Hayashi, Norio; Matsuura, Yukihiro

    2014-07-01

    Our purpose in this study was to develop a functional form of radiography and to perform a quantitative analysis for the shoulder joint using a dynamic flat panel detector (FPD) system. We obtained dynamic images at a rate of 3.75 frames per second (fps) using an FPD system. Three patients and 5 healthy controls were studied with a clinically established frontal projection, with abduction of the arms. The arm angle, glenohumeral angle (G-angle), and scapulothoracic angle (S-angle) were measured on dynamic images. The ratio of the G-angle to the S-angle (GSR) was also evaluated quantitatively. In normal subjects, the G-angle and S-angle changed gradually along with the arm angle. The G-angle was approximately twice as large as the S-angle, resulting in a GSR of 2 throughout the abduction of the shoulder. Changes in G-angle and S-angle tended to be irregular in patients with shoulder disorders. The GSR of the thoracic outlet syndrome, recurrent dislocation of the shoulder joint, and anterior serratus muscle paralysis were 3-7.5, 4-9.5, and 3.5-7.5, respectively. The GSR of the anterior serratus muscle paralysis improved to approximately 2 after orthopedic treatment. Our preliminary results indicated that functional radiography by FPD and computer-aided quantitative analysis is useful for diagnosis of some shoulder disorders, such as the thoracic outlet syndrome, recurrent dislocation of the shoulder joint, and anterior serratus muscle paralysis. The technique and procedures described comprise a simple, functional shoulder radiographic method for evaluation of the therapeutic effects of surgery and/or rehabilitation.

  12. Detectability of regional lung ventilation with flat-panel detector-based dynamic radiography.

    PubMed

    Tanaka, Rie; Sanada, Shigeru; Okazaki, Nobuo; Kobayashi, Takeshi; Suzuki, Masayuki; Matsui, Takeshi; Matsui, Osamu

    2008-03-01

    This study was performed to investigate the ability of breathing chest radiography using flat-panel detector (FPD) to quantify relative local ventilation. Dynamic chest radiographs during respiration were obtained using a modified FPD system. Imaging was performed in three different positions, ie, standing and right and left decubitus positions, to change the distribution of local ventilation. We measured the average pixel value in the local lung area. Subsequently, the interframe differences, as well as difference values between maximum inspiratory and expiratory phases, were calculated. The results were visualized as images in the form of a color display to show more or less x-ray translucency. Temporal changes and spatial distribution of the results were then compared to lung physiology. In the results, the average pixel value in each lung was associated with respiratory phase. In all positions, respiratory changes of pixel value in the lower area were greater than those in the upper area (P < 0.01), which was the same tendency as the regional differences in ventilation determined by respiratory physiology. In addition, in the decubitus position, it was observed that areas with large respiratory changes in pixel value moved up in the vertical direction during expiration, which was considered to be airway closure. In conclusion, breathing chest radiography using FPD was shown to be capable of quantifying relative ventilation in local lung area and detecting regional differences in ventilation and timing of airway closure. This method is expected to be useful as a new diagnostic imaging modality for evaluating relative local ventilation.

  13. Comparison measurements of DQE for two flat panel detectors: fluoroscopic detector vs. cone beam CT detector

    NASA Astrophysics Data System (ADS)

    Betancourt Benítez, Ricardo; Ning, Ruola; Conover, David

    2006-03-01

    The physical performance of two flat panel detectors (FPD) has been evaluated using a standard x-ray beam quality set by IEC, namely RQA5. The FPDs evaluated in this study are based on an amorphous silicon photodiode array that is coupled to a thallium-doped Cesium Iodide scintillator and to a thin film transistor (TFT) array. One detector is the PaxScan 2520 that is designed for fluoro imaging, and has a small dynamic range and a large image lag. The other detector is the PaxScan 4030CB that is designed for cone beam CT, and has a large dynamic range (>16-bit), a reduced image lag and many imaging modes. Varian Medical Systems manufactured both detectors. The linearity of the FPDs was investigated by using an ionization chamber and aluminum filtration in order to obtain the beam quality. Since the FPDs are used in fluoroscopic mode, image lag of the FPD was measured in order to investigate its effect on this study, especially its effect on DQE. The spatial resolution of the FPDs was determined by obtaining the pre-sampling modulation transfer function for each detector. A sharp edge was used in accordance to IEC 62220-1. Next, the Normalized Noise Power Spectrum (NNPS) was calculated for various exposures levels at RQA5 radiation quality. Finally, the DQE of each FPD was obtained with a modified version of the international standard set by IEC 62220-1. The results show that the physical performance in DQE and MTF of the PaxScan 4030CB is superior to that of PaxScan2520.

  14. Effects of Tangential Edge Constraints on the Postbuckling Behavior of Flat and Curved Panels Subjected to Thermal and Mechanical Loads

    NASA Technical Reports Server (NTRS)

    Lin, W.; Librescu, L.; Nemeth, M. P.; Starnes, J. H. , Jr.

    1994-01-01

    A parametric study of the effects of tangential edge constraints on the postbuckling response of flat and shallow curved panels subjected to thermal and mechanical loads is presented. The mechanical loads investigated are uniform compressive edge loads and transverse lateral pressure. The temperature fields considered are associated with spatially nonuniform heating over the panels, and a linear through-the-thickness temperature gradient. The structural model is based on a higher-order transverse-shear-deformation theory of shallow shells that incorporates the effects of geometric nonlinearities, initial geometric imperfections, and tangential edge motion constraints. Results are presented for three-layer sandwich panels made from transversely isotropic materials. Simply supported panels are considered in which the tangential motion of the unloaded edges is either unrestrained, partially restrained, or fully restrained. These results focus on the effects of the tangential edge restraint on the postbuckling response. The results of this study indicate that tangentially restraining the edges of a curved panel can make the panel insensitive to initial geometric imperfections in some cases.

  15. Theoretical investigation of flutter of two-dimensional flat panels with one surface exposed to supersonic potential flow

    NASA Technical Reports Server (NTRS)

    Nelson, Herbert C; Cunningham, Herbert J

    1956-01-01

    A Rayleigh type analysis involving chosen modes of the panel as degrees of freedom is used to treat the flutter of a two-dimensional flat panel supported at its leading and trailing edges and subjected to a middle-plane tensile force. The panel has a supersonic stream passing over its upper surface and still air below. The aerodynamic forces due to the supersonic stream are obtained from the theory for linearized two-dimensional unsteady flow and the forces due to the still air are obtained from acoustical theory. In order to study the effect of increasing the number of modes in the analysis, two and then four modes are employed. The modes used are the first four natural modes of the panel in a vacuum with no tensile force acting. The analysis includes these variables: Mach number, structural damping, tensile force, density of the still air, and edge fixity (clamped and pinned). For certain combinations of these variables, stability boundaries are obtained which can be used to determine the panel thickness required to prevent flutter for any panel material and altitude.

  16. Handbook of structural stability part V : compressive strength of flat stiffened panels

    NASA Technical Reports Server (NTRS)

    Gerard, George

    1957-01-01

    A generalized crippling analysis for short monolithic panels with formed or extruded stiffeners is presented. Methods are presented for determining if riveted panels act in a monolithic manner and for determining the strength of those which do not. The failure modes of intermediate-length and long stiffened panels are discussed and methods given for estimating column strength. Theory and test data on optimum stiffened panels are presented and the various factors of importance in box types of construction are considered.

  17. User's manual: Subsonic/supersonic advanced panel pilot code

    NASA Technical Reports Server (NTRS)

    Moran, J.; Tinoco, E. N.; Johnson, F. T.

    1978-01-01

    Sufficient instructions for running the subsonic/supersonic advanced panel pilot code were developed. This software was developed as a vehicle for numerical experimentation and it should not be construed to represent a finished production program. The pilot code is based on a higher order panel method using linearly varying source and quadratically varying doublet distributions for computing both linearized supersonic and subsonic flow over arbitrary wings and bodies. This user's manual contains complete input and output descriptions. A brief description of the method is given as well as practical instructions for proper configurations modeling. Computed results are also included to demonstrate some of the capabilities of the pilot code. The computer program is written in FORTRAN IV for the SCOPE 3.4.4 operations system of the Ames CDC 7600 computer. The program uses overlay structure and thirteen disk files, and it requires approximately 132000 (Octal) central memory words.

  18. Cone-beam CT with a flat-panel detector: From image science to image-guided surgery

    NASA Astrophysics Data System (ADS)

    Siewerdsen, Jeffrey H.

    2011-08-01

    The development of large-area flat-panel X-ray detectors (FPDs) has spurred investigation in a spectrum of advanced medical imaging applications, including tomosynthesis and cone-beam CT (CBCT). Recent research has extended image quality metrics and theoretical models to such applications, providing a quantitative foundation for the assessment of imaging performance as well as a general framework for the design, optimization, and translation of such technologies to new applications. For example, cascaded systems models of the Fourier domain metrics, such as noise-equivalent quanta (NEQ), have been extended to these modalities to describe the propagation of signal and noise through the image acquisition and reconstruction chain and to quantify the factors that govern spatial resolution, image noise, and detectability. Moreover, such models have demonstrated basic agreement with human observer performance for a broad range of imaging conditions and imaging tasks. These developments in image science have formed a foundation for the knowledgeable development and translation of CBCT to new applications in image-guided interventions—for example, CBCT implemented on a mobile surgical C-arm for intraoperative 3D imaging. The ability to acquire high-quality 3D images on demand during surgical intervention overcomes conventional limitations of surgical guidance in the context of preoperative images alone. A prototype mobile C-arm developed in academic-industry partnership demonstrates CBCT with low radiation dose, sub-mm spatial resolution, and soft-tissue visibility potentially approaching that of diagnostic CT. Integration of the 3D imaging system with real-time tracking, deformable registration, endoscopic video, and 3D visualization offers a promising addition to the surgical arsenal in interventions ranging from head-and-neck/skull base surgery to spine, orthopaedic, thoracic, and abdominal surgeries. Cadaver studies show the potential for significant boosts in

  19. High-resolution secondary reconstructions with the use of flat panel CT in the clinical assessment of patients with cochlear implants.

    PubMed

    Pearl, M S; Roy, A; Limb, C J

    2014-06-01

    Radiologic assessment of cochlear implants can be limited because of metallic streak artifacts and the high attenuation of the temporal bones. We report on 14 patients with 18 cochlear implants (17 Med-El standard 31.5-mm arrays, 1 Med-El medium 24-mm array) who underwent flat panel CT with the use of high-resolution secondary reconstruction techniques. Flat panel CT depicted the insertion site, cochlear implant course, and all 216 individual electrode contacts. The calculated mean angular insertion depth for standard arrays was 591.9° (SD = 70.9; range, 280°). High-resolution secondary reconstructions of the initial flat panel CT dataset, by use of a manually generated field of view, Hounsfield unit kernel type, and sharp image characteristics, provided high-quality images with improved spatial resolution. Flat panel CT is a promising imaging tool for the postoperative evaluation of cochlear implant placement.

  20. Scan equalization digital radiography (SEDR) implemented with an amorphous selenium flat-panel detector: initial experience.

    PubMed

    Liu, Xinming; Lai, Chao-Jen; Chen, Lingyun; Han, Tao; Zhong, Yuncheng; Shen, Youtao; Wang, Tianpeng; Shaw, Chris C

    2009-11-21

    It is well recognized in projection radiography that low-contrast detectability suffers in heavily attenuating regions due to excessively low x-ray fluence to the image receptor and higher noise levels. Exposure equalization can improve image quality by increasing the x-ray exposure to heavily attenuating regions, resulting in a more uniform distribution of exposure to the detector. Image quality is also expected to be improved by using the slot-scan geometry to reject scattered radiation effectively without degrading primary x-rays. This paper describes the design of a prototype scan equalization digital radiography (SEDR) system implemented with an amorphous silicon (a-Si) thin-film transistor (TFT) array-based flat-panel detector. With this system, slot-scan geometry with alternate line erasure and readout (ALER) technique was used to achieve scatter rejection. A seven-segment beam height modulator assembly was mounted onto the fore collimator to regulate exposure regionally for chest radiography. The beam modulator assembly, consisting of micro linear motors, lead screw cartridge with lead (Pb) beam blockers attached, position feedback sensors and motor driver circuitry, has been tested and found to have an acceptable response for exposure equalization in chest radiography. An anthropomorphic chest phantom was imaged in the posterior-anterior (PA) view under clinical conditions. Scatter component, primary x-rays, scatter-to-primary ratios (SPRs) and primary signal-to-noise ratios (PSNRs) were measured in the SEDR images to evaluate the rejection and redistribution of scattered radiation, and compared with those for conventional full-field imaging with and without anti-scatter grid methods. SPR reduction ratios (SPRRRs, defined as the differences between the non-grid full-field SPRs and the reduced SPRs divided by the former) yielded approximately 59% for the full-field imaging with grid and 82% for the SEDR technique in the lungs, and 77% for the full

  1. An investigation of flat panel equipment variables on image quality with a dedicated cardiac phantom

    NASA Astrophysics Data System (ADS)

    Dragusin, O.; Bosmans, H.; Pappas, C.; Desmet, W.

    2008-09-01

    Image quality (IQ) evaluation plays a key role in the process of optimization of new x-ray systems. Ideally, this process should be supported by real clinical images, but ethical issues and differences in anatomy and pathology of patients make it impossible. Phantom studies might overcome these issues. This paper presents the IQ evaluation of 30 cineangiographic films acquired with a cardiac flat panel system. The phantom used simulates the anatomy of the heart and allows the circulation of contrast agent boluses through coronary arteries. Variables investigated with influence on IQ and radiation dose are: tube potential, detector dose, added Copper filters, dynamic density optimization (DDO) and viewing angle. The IQ evaluation consisted of scoring 4 simulated calcified lesions located on different coronary artery segments in terms of degree of visualization. Eight cardiologists rated the lesions using a five-point scale ((1) lesion not visible to (5) very good visibility). Radiation doses associated to the angiograms are expressed in terms of incident air kerma (IAK) and effective dose that has been calculated with PCXMX software (STUK, Finland) from the exposure settings assuming a standard sized patient of 70 Kg. Mean IQ scores ranged from 1.68 to 4.88. The highest IQ scores were obtained for the angiograms acquired with tube potential 80 kVp, no added Cu filters, DDO 60%, RAO and LAO views and the highest entrance detector dose that has been used in the present study, namely 0.17 μGy/im. Radiation doses (IAK ~40 mGy and effective dose of 1 mSv) were estimated for angiograms acquired at 15 frames s-1, detector field-of-view 20 cm, and a length of 5 s. The following parameters improved the IQ factor significantly: a change in tube potential from 96 to 80 kVp, detector dose from 0.10 μGy/im to 0.17 μGy/im, the absence of Copper filtration. DDO variable which is a post-processing parameter should be carefully evaluated because it alters the quality of the

  2. Amorphous and polycrystalline photoconductors for direct conversion flat panel x-ray image sensors.

    PubMed

    Kasap, Safa; Frey, Joel B; Belev, George; Tousignant, Olivier; Mani, Habib; Greenspan, Jonathan; Laperriere, Luc; Bubon, Oleksandr; Reznik, Alla; DeCrescenzo, Giovanni; Karim, Karim S; Rowlands, John A

    2011-01-01

    In the last ten to fifteen years there has been much research in using amorphous and polycrystalline semiconductors as x-ray photoconductors in various x-ray image sensor applications, most notably in flat panel x-ray imagers (FPXIs). We first outline the essential requirements for an ideal large area photoconductor for use in a FPXI, and discuss how some of the current amorphous and polycrystalline semiconductors fulfill these requirements. At present, only stabilized amorphous selenium (doped and alloyed a-Se) has been commercialized, and FPXIs based on a-Se are particularly suitable for mammography, operating at the ideal limit of high detective quantum efficiency (DQE). Further, these FPXIs can also be used in real-time, and have already been used in such applications as tomosynthesis. We discuss some of the important attributes of amorphous and polycrystalline x-ray photoconductors such as their large area deposition ability, charge collection efficiency, x-ray sensitivity, DQE, modulation transfer function (MTF) and the importance of the dark current. We show the importance of charge trapping in limiting not only the sensitivity but also the resolution of these detectors. Limitations on the maximum acceptable dark current and the corresponding charge collection efficiency jointly impose a practical constraint that many photoconductors fail to satisfy. We discuss the case of a-Se in which the dark current was brought down by three orders of magnitude by the use of special blocking layers to satisfy the dark current constraint. There are also a number of polycrystalline photoconductors, HgI(2) and PbO being good examples, that show potential for commercialization in the same way that multilayer stabilized a-Se x-ray photoconductors were developed for commercial applications. We highlight the unique nature of avalanche multiplication in a-Se and how it has led to the development of the commercial HARP video-tube. An all solid state version of the HARP has been

  3. Optimization of a flat-panel based real time dual-energy system for cardiac imaging.

    PubMed

    Ducote, Justin L; Xu, Tong; Molloi, Sabee

    2006-06-01

    A simulation study was conducted to evaluate the effects of high-energy beam filtration, dual-gain operation and noise reduction on dual-energy images using a digital flat-panel detector. High-energy beam filtration increases image contrast through greater beam separation and tends to reduce total radiation exposure and dose per image pair. It is also possible to reduce dual-energy image noise by acquiring low and high-energy images at two different detector gains. In addition, dual-energy noise reduction algorithms can further reduce image noise. The cumulative effect of these techniques applied in series was investigated in this study. The contrast from a small thickness of calcium was simulated over a step phantom of tissue equivalent material with a CsI phosphor as the image detector. The dual-energy contrast-to-noise ratio was calculated using values of energy absorption and energy variance. A figure-of-merit (FOM) was calculated from dual-energy contrast-to-noise ratio (CNR) and patient effective dose estimated from values of entrance exposure. Filter atomic numbers in the range of 1-100 were considered with thicknesses ranging from 0-2500 mg/cm2. The simulation examined combinations of the above techniques which maximized the FOM. The application of a filter increased image contrast by as much as 45%. Near maximal increases were seen for filter atomic numbers in the range of 40-60 and 85-100 with masses above 750 mg/cm2. Increasing filter thickness beyond 1000 mg/cm2 increased tube loading without further significant contrast enhancement. No additional FOM improvements were seen with dual gain before or after the application of any noise reduction algorithm. Narrow beam experiments were carried out to verify predictions. The measured FOM increased by more than a factor of 3.5 for a silver filter thickness of 800 microm, equal energy weighting and application of a noise clipping algorithm. The main limitation of dynamic high-energy filtration is increased

  4. An investigation of flat panel equipment variables on image quality with a dedicated cardiac phantom.

    PubMed

    Dragusin, O; Bosmans, H; Pappas, C; Desmet, W

    2008-09-21

    Image quality (IQ) evaluation plays a key role in the process of optimization of new x-ray systems. Ideally, this process should be supported by real clinical images, but ethical issues and differences in anatomy and pathology of patients make it impossible. Phantom studies might overcome these issues. This paper presents the IQ evaluation of 30 cineangiographic films acquired with a cardiac flat panel system. The phantom used simulates the anatomy of the heart and allows the circulation of contrast agent boluses through coronary arteries. Variables investigated with influence on IQ and radiation dose are: tube potential, detector dose, added Copper filters, dynamic density optimization (DDO) and viewing angle. The IQ evaluation consisted of scoring 4 simulated calcified lesions located on different coronary artery segments in terms of degree of visualization. Eight cardiologists rated the lesions using a five-point scale ((1) lesion not visible to (5) very good visibility). Radiation doses associated to the angiograms are expressed in terms of incident air kerma (IAK) and effective dose that has been calculated with PCXMX software (STUK, Finland) from the exposure settings assuming a standard sized patient of 70 Kg. Mean IQ scores ranged from 1.68 to 4.88. The highest IQ scores were obtained for the angiograms acquired with tube potential 80 kVp, no added Cu filters, DDO 60%, RAO and LAO views and the highest entrance detector dose that has been used in the present study, namely 0.17 microGy/im. Radiation doses (IAK approximately 40 mGy and effective dose of 1 mSv) were estimated for angiograms acquired at 15 frames s(-1), detector field-of-view 20 cm, and a length of 5 s. The following parameters improved the IQ factor significantly: a change in tube potential from 96 to 80 kVp, detector dose from 0.10 microGy/im to 0.17 microGy/im, the absence of Copper filtration. DDO variable which is a post-processing parameter should be carefully evaluated because it alters

  5. [Flat-panel detector technology -State-of-the-art and future prospects-].

    PubMed

    Yamazaki, Tatsuya

    2002-01-01

    A flat-panel detector (FPD) is a long-awaited technology to implement the digital X-ray imaging technology into the radiological department. This paper describes the state-of-the-art technology and future prospects on the FPD technology. State-of-the-art technology was reviewed taking the CXDI series as an example. Several FPD-based systems have been introduced into the Japanese market since CXDI-11 opened it in November 1998. Accompanying CXDI-C2 for control, CXDI-22 for table position and CXDI-31 for portable, the CXDI series fulfills the requirement of the radiography room being a fully digitalized room. The FPD on the CXDI series is comprised of a scintillator (Gd(2)O(2)S:Tb(3+)) as a primary sensor in which the X-ray is captured and an amorphous silicon detector (LANMIT) as a secondary sensor in which the fluorescent light is detected. Since the scintillator is identical to that of the screen-film systems, it can be said as proven, durable and chemically stable and it is expected to produce the same image quality as the screen-film systems. CXDI-31, a portable FPD-based system, was developed targeting thinner dimensions, lightweight, durability and high spatial resolution. Thoroughly re-designing the mechanical structure and reducing the power consumption at the readout IC realized thinner dimensions. Introducing the portable note PC technologies successfully combined lightweight with durability. Improving the sensor process and re-designing the layout made the sensor high resolution without compromising the signal-to-noise ratio. Future prospects were overviewed in the aspect of technology and applications. Sensitivity, spatial resolution, frame rate and portability were described as the upcoming technology. Increasing gain and reducing noise will realize higher sensitivity, especially by adopting the PbI(2), HgI(2) or such photoconductor materials as the primary sensor. Pixelized amplifier will also achieve higher sensitivity. Layered sensor designed such

  6. Optimization of a flat-panel based real time dual-energy system for cardiac imaging

    SciTech Connect

    Ducote, Justin L.; Xu Tong; Molloi, Sabee

    2006-06-15

    A simulation study was conducted to evaluate the effects of high-energy beam filtration, dual-gain operation and noise reduction on dual-energy images using a digital flat-panel detector. High-energy beam filtration increases image contrast through greater beam separation and tends to reduce total radiation exposure and dose per image pair. It is also possible to reduce dual-energy image noise by acquiring low and high-energy images at two different detector gains. In addition, dual-energy noise reduction algorithms can further reduce image noise. The cumulative effect of these techniques applied in series was investigated in this study. The contrast from a small thickness of calcium was simulated over a step phantom of tissue equivalent material with a CsI phosphor as the image detector. The dual-energy contrast-to-noise ratio was calculated using values of energy absorption and energy variance. A figure-of-merit (FOM) was calculated from dual-energy contrast-to-noise ratio (CNR) and patient effective dose estimated from values of entrance exposure. Filter atomic numbers in the range of 1-100 were considered with thicknesses ranging from 0-2500 mg/cm{sup 2}. The simulation examined combinations of the above techniques which maximized the FOM. The application of a filter increased image contrast by as much as 45%. Near maximal increases were seen for filter atomic numbers in the range of 40-60 and 85-100 with masses above 750 mg/cm{sup 2}. Increasing filter thickness beyond 1000 mg/cm{sup 2} increased tube loading without further significant contrast enhancement. No additional FOM improvements were seen with dual gain before or after the application of any noise reduction algorithm. Narrow beam experiments were carried out to verify predictions. The measured FOM increased by more than a factor of 3.5 for a silver filter thickness of 800 {mu}m, equal energy weighting and application of a noise clipping algorithm. The main limitation of dynamic high-energy filtration

  7. Measurement of joint kinematics using a conventional clinical single-perspective flat-panel radiography system

    SciTech Connect

    Seslija, Petar; Teeter, Matthew G.; Yuan Xunhua; Naudie, Douglas D. R.; Bourne, Robert B.; MacDonald, Steven J.; Peters, Terry M.; Holdsworth, David W.

    2012-10-15

    Purpose: The ability to accurately measure joint kinematics is an important tool in studying both normal joint function and pathologies associated with injury and disease. The purpose of this study is to evaluate the efficacy, accuracy, precision, and clinical safety of measuring 3D joint motion using a conventional flat-panel radiography system prior to its application in an in vivo study. Methods: An automated, image-based tracking algorithm was implemented to measure the three-dimensional pose of a sparse object from a two-dimensional radiographic projection. The algorithm was tested to determine its efficiency and failure rate, defined as the number of image frames where automated tracking failed, or required user intervention. The accuracy and precision of measuring three-dimensional motion were assessed using a robotic controlled, tibiofemoral knee phantom programmed to mimic a subject with a total knee replacement performing a stair ascent activity. Accuracy was assessed by comparing the measurements of the single-plane radiographic tracking technique to those of an optical tracking system, and quantified by the measurement discrepancy between the two systems using the Bland-Altman technique. Precision was assessed through a series of repeated measurements of the tibiofemoral kinematics, and was quantified using the across-trial deviations of the repeated kinematic measurements. The safety of the imaging procedure was assessed by measuring the effective dose of ionizing radiation associated with the x-ray exposures, and analyzing its relative risk to a human subject. Results: The automated tracking algorithm displayed a failure rate of 2% and achieved an average computational throughput of 8 image frames/s. Mean differences between the radiographic and optical measurements for translations and rotations were less than 0.08 mm and 0.07 Degree-Sign in-plane, and 0.24 mm and 0.6 Degree-Sign out-of-plane. The repeatability of kinematics measurements performed

  8. Amorphous and Polycrystalline Photoconductors for Direct Conversion Flat Panel X-Ray Image Sensors

    PubMed Central

    Kasap, Safa; Frey, Joel B.; Belev, George; Tousignant, Olivier; Mani, Habib; Greenspan, Jonathan; Laperriere, Luc; Bubon, Oleksandr; Reznik, Alla; DeCrescenzo, Giovanni; Karim, Karim S.; Rowlands, John A.

    2011-01-01

    In the last ten to fifteen years there has been much research in using amorphous and polycrystalline semiconductors as x-ray photoconductors in various x-ray image sensor applications, most notably in flat panel x-ray imagers (FPXIs). We first outline the essential requirements for an ideal large area photoconductor for use in a FPXI, and discuss how some of the current amorphous and polycrystalline semiconductors fulfill these requirements. At present, only stabilized amorphous selenium (doped and alloyed a-Se) has been commercialized, and FPXIs based on a-Se are particularly suitable for mammography, operating at the ideal limit of high detective quantum efficiency (DQE). Further, these FPXIs can also be used in real-time, and have already been used in such applications as tomosynthesis. We discuss some of the important attributes of amorphous and polycrystalline x-ray photoconductors such as their large area deposition ability, charge collection efficiency, x-ray sensitivity, DQE, modulation transfer function (MTF) and the importance of the dark current. We show the importance of charge trapping in limiting not only the sensitivity but also the resolution of these detectors. Limitations on the maximum acceptable dark current and the corresponding charge collection efficiency jointly impose a practical constraint that many photoconductors fail to satisfy. We discuss the case of a-Se in which the dark current was brought down by three orders of magnitude by the use of special blocking layers to satisfy the dark current constraint. There are also a number of polycrystalline photoconductors, HgI2 and PbO being good examples, that show potential for commercialization in the same way that multilayer stabilized a-Se x-ray photoconductors were developed for commercial applications. We highlight the unique nature of avalanche multiplication in a-Se and how it has led to the development of the commercial HARP video-tube. An all solid state version of the HARP has been

  9. Direct-reading design charts for 75S-T6 aluminum-alloy flat compression panels having longitudinal extruded Z-section stiffeners

    NASA Technical Reports Server (NTRS)

    Hickman, William A; Dow, Norris F

    1951-01-01

    Direct-reading design charts are presented for 75S-T6 aluminum-alloy flat compression panels having longitudinal extruded Z-section stiffeners. These charts, which cover a wide range of proportions, make possible the direct determination of the stress and all panel dimensions required to carry a given intensity of loading with a given skin thickness and effective length of panel.

  10. Calibration model of a dual gain flat panel detector for 2D and 3D x-ray imaging

    SciTech Connect

    Schmidgunst, C.; Ritter, D.; Lang, E.

    2007-09-15

    The continuing research and further development in flat panel detector technology have led to its integration into more and more medical x-ray systems for two-dimensional (2D) and three-dimensional (3D) imaging, such as fixed or mobile C arms. Besides the obvious advantages of flat panel detectors, like the slim design and the resulting optimum accessibility to the patient, their success is primarily a product of the image quality that can be achieved. The benefits in the physical and performance-related features as opposed to conventional image intensifier systems (e.g., distortion-free reproduction of imaging information or almost linear signal response over a large dynamic range) can be fully exploited, however, only if the raw detector images are correctly calibrated and postprocessed. Previous procedures for processing raw data contain idealizations that, in the real world, lead to artifacts or losses in image quality. Thus, for example, temperature dependencies or changes in beam geometry, as can occur with mobile C arm systems, have not been taken into account up to this time. Additionally, adverse characteristics such as image lag or aging effects have to be compensated to attain the best possible image quality. In this article a procedure is presented that takes into account the important dependencies of the individual pixel sensitivity of flat panel detectors used in 2D or 3D imaging and simultaneously minimizes the work required for an extensive recalibration. It is suitable for conventional detectors with only one gain mode as well as for the detectors specially developed for 3D imaging with dual gain read-out technology.

  11. Monte Carlo calculation of the spatial response (Modulated Transfer Function) of a scintillation flat panel and comparison with experimental results

    NASA Astrophysics Data System (ADS)

    Juste, Belén; Miró, Rafael; Monasor, Paula; Verdú, Gumersindo

    2015-11-01

    Phosphor screens are commonly used in many X-ray imaging applications. The design and optimization of these detectors can be achieved using Monte Carlo codes to simulate radiation transport in scintillation materials and to improve the spatial response. This work presents an exhaustive procedure to measure the spatial resolution of a scintillation flat panel image and to evaluate the agreement with data obtained by simulation. To evaluate the spatial response we have used the Modulated Transfer Function (MTF) parameter. According to this, we have obtained the Line Spread Function (LSF) of the system since the Fourier Transform (FT) of the LSF gives the MTF. The experimental images were carried out using a medical X-ray tube (Toshiba E7299X) and a flat panel (Hammamatsu C9312SK). Measurements were based on the slit methodology experimental implementation, which measures the response of the system to a line. LSF measurements have been performed using a 0.2 mm wide lead slit superimposed over the flat panel. The detector screen was modelled with MCNP (version 6) Monte Carlo simulation code in order to analyze the effect of the acquisition setup configuration and to compare the response of scintillator screens with the experimental results. MCNP6 offers the possibility of studying the optical physics parameters (optical scattering and absorption coefficients) that occur in the phosphor screen. The study has been tested for different X-ray tube voltages, from 100 to 140 kV. An acceptable convergence between the MTF results obtained with MCNP6 and the experimental measurements have been obtained.

  12. Calibration model of a dual gain flat panel detector for 2D and 3D x-ray imaging.

    PubMed

    Schmidgunst, C; Ritter, D; Lang, E

    2007-09-01

    The continuing research and further development in flat panel detector technology have led to its integration into more and more medical x-ray systems for two-dimensional (2D) and three-dimensional (3D) imaging, such as fixed or mobile C arms. Besides the obvious advantages of flat panel detectors, like the slim design and the resulting optimum accessibility to the patient, their success is primarily a product of the image quality that can be achieved. The benefits in the physical and performance-related features as opposed to conventional image intensifier systems, (e.g., distortion-free reproduction of imaging information or almost linear signal response over a large dynamic range) can be fully exploited, however, only if the raw detector images are correctly calibrated and postprocessed. Previous procedures for processing raw data contain idealizations that, in the real world, lead to artifacts or losses in image quality. Thus, for example, temperature dependencies or changes in beam geometry, as can occur with mobile C arm systems, have not been taken into account up to this time. Additionally, adverse characteristics such as image lag or aging effects have to be compensated to attain the best possible image quality. In this article a procedure is presented that takes into account the important dependencies of the individual pixel sensitivity of flat panel detectors used in 2D or 3D imaging and simultaneously minimizes the work required for an extensive recalibration. It is suitable for conventional detectors with only one gain mode as well as for the detectors specially developed for 3D imaging with dual gain read-out technology.

  13. Development of a real-time digital radiography system using a scintillator-type flat-panel detector

    NASA Astrophysics Data System (ADS)

    Ikeda, Shigeyuki; Suzuki, Katsumi; Ishikawa, Ken; Okajima, Kenichi

    2001-06-01

    In order to study the advantage and remaining problems of FPD (flat panel detector) for clinical use by the real-time DR (digital radiography) system, we developed a prototype system using a scintillator type FPD and which was compared with previous I.I.-CCD type real-time DR. We replaced the X- ray detector of DR-2000X from I.I.-4M (4 million pixels)-CCD camera to the scintillator type dynamic FPD(7' X 9', 127 micrometers ), which can take both radiographic and fluoroscopic images. We obtained the images of head and stomach phantoms, and discussed about the image quality with medical doctors.

  14. Cone-beam CT breast imaging with a flat panel detector: a simulation study

    NASA Astrophysics Data System (ADS)

    Chen, Lingyun; Shaw, Chris C.; Tu, Shu-Ju; Altunbas, Mustafa C.; Wang, Tianpeng; Lai, Chao-Jen; Liu, Xinming; Kappadath, S. C.

    2005-04-01

    This paper investigates the feasibility of using a flat panel based cone-beam computer tomography (CT) system for 3-D breast imaging with computer simulation and imaging experiments. In our simulation study, 3-D phantoms were analytically modeled to simulate a breast loosely compressed into cylindrical shape with embedded soft tissue masses and calcifications. Attenuation coefficients were estimated to represent various types of breast tissue, soft tissue masses and calcifications to generate realistic image signal and contrast. Projection images were computed to incorporate x-ray attenuation, geometric magnification, x-ray detection, detector blurring, image pixelization and digitization. Based on the two-views mammography comparable dose level on the central axis of the phantom (also the rotation axis), x-ray kVp/filtration, transmittance through the phantom, detected quantum efficiency (DQE), exposure level, and imaging geometry, the photon fluence was estimated and used to estimate the phantom noise level on a pixel-by-pixel basis. This estimated noise level was then used with the random number generator to produce and add a fluctuation component to the noiseless transmitted image signal. The noise carrying projection images were then convolved with a Gaussian-like kernel, computed from measured 1-D line spread function (LSF) to simulated detector blurring. Additional 2-D Gaussian-like kernel is designed to suppress the noise fluctuation that inherently originates from projection images so that the reconstructed image detectability of low contrast masses phantom can be improved. Image reconstruction was performed using the Feldkamp algorithm. All simulations were performed on a 24 PC (2.4 GHz Dual-Xeon CPU) cluster with MPI parallel programming. With 600 mrads mean glandular dose (MGD) at the phantom center, soft tissue masses as small as 1 mm in diameter can be detected in a 10 cm diameter 50% glandular 50% adipose or fatter breast tissue, and 2 mm or larger

  15. Fiber-Reinforced-Foam (FRF) Core Composite Sandwich Panel Concept for Advanced Composites Technologi

    NASA Technical Reports Server (NTRS)

    2010-01-01

    Fiber-Reinforced-Foam (FRF) Core Composite Sandwich Panel Concept for Advanced Composites Technologies Project - Preliminary Manufacturing Demonstration Articles for Ares V Payload Shroud Barrel Acreage Structure

  16. Use of personal digital assistants for retrieval of medical images and data on high-resolution flat panel displays.

    PubMed

    Ratib, Osman; McCoy, J Michael; McGill, D Ric; Li, Minglin; Brown, Allen

    2003-01-01

    For its new acute care hospital, the University of California at Los Angeles is evaluating innovative technology involving high-resolution flat panel display devices configured as "network appliances" that can be wall mounted for use in the retrieval and display of medical images and data. Physicians and healthcare providers can log on with wireless handheld computers, which can serve as an identification device as well as a navigational tool for selecting patient records and data. These data are displayed and manipulated on the flat panel display without the need for a keyboard or mouse. A prototype was developed with commercially available image display software, which was modified to allow the remote control of software functions from a handheld device through an infrared communication port. The system also allows navigation through the patient data in a World Wide Web-based electronic patient record. This prototype illustrates the evolution of radiologic facilities toward "shareable" high-quality display devices that allow more convenient and cost-effective access to medical images and related data in complex clinical environments, resulting in a paradigm shift in data navigation and accessibility.

  17. Comparison of the imaging physics performance of a prototype flat-panel detector with a 400-speed screen-film system

    NASA Astrophysics Data System (ADS)

    Huda, Walter; Ogden, Kent M.; Roskopf, Marsha L.; Rush, Charles

    2001-06-01

    The performance of a digital radiography system that included a prototype flat panel detector (StingRay) was compared with a 400 speed screen-film system. The flat panel detector consisted of a 500 micrometers thick CsI scintillator with an image matrix size of 3k2. The limiting spatial resolution of screen-film (approximately 4 line pairs/mm) was superior to that of the flat panel detector (approximately 2.5 line pairs/mm). The digital detector had an excellent linearity response (r2 equals 0.997), a dynamic range of 20,000:1, and saturated at a radiation exposure of 60 mR.

  18. Reduction of ring artifacts in CBCT: Detection and correction of pixel gain variations in flat panel detectors

    SciTech Connect

    Altunbas, Cem; Lai, Chao-Jen; Zhong, Yuncheng; Shaw, Chris C.

    2014-09-15

    Purpose: In using flat panel detectors (FPD) for cone beam computed tomography (CBCT), pixel gain variations may lead to structured nonuniformities in projections and ring artifacts in CBCT images. Such gain variations can be caused by change in detector entrance exposure levels or beam hardening, and they are not accounted by conventional flat field correction methods. In this work, the authors presented a method to identify isolated pixel clusters that exhibit gain variations and proposed a pixel gain correction (PGC) method to suppress both beam hardening and exposure level dependent gain variations. Methods: To modulate both beam spectrum and entrance exposure, flood field FPD projections were acquired using beam filters with varying thicknesses. “Ideal” pixel values were estimated by performing polynomial fits in both raw and flat field corrected projections. Residuals were calculated by taking the difference between measured and ideal pixel values to identify clustered image and FPD artifacts in flat field corrected and raw images, respectively. To correct clustered image artifacts, the ratio of ideal to measured pixel values in filtered images were utilized as pixel-specific gain correction factors, referred as PGC method, and they were tabulated as a function of pixel value in a look-up table. Results: 0.035% of detector pixels lead to clustered image artifacts in flat field corrected projections, where 80% of these pixels were traced back and linked to artifacts in the FPD. The performance of PGC method was tested in variety of imaging conditions and phantoms. The PGC method reduced clustered image artifacts and fixed pattern noise in projections, and ring artifacts in CBCT images. Conclusions: Clustered projection image artifacts that lead to ring artifacts in CBCT can be better identified with our artifact detection approach. When compared to the conventional flat field correction method, the proposed PGC method enables characterization of nonlinear

  19. Post-buckling of geometrically imperfect shear-deformable flat panels under combined thermal and compressive edge loadings

    NASA Technical Reports Server (NTRS)

    Librescu, L.; Souza, M. A.

    1993-01-01

    The static post-buckling of simply-supported flat panels exposed to a stationary nonuniform temperature field and subjected to a system of subcritical in-plane compressive edge loads is investigated. The study is performed within a refined theory of composite laminated plates incorporating the effect of transverse shear and the geometric nonlinearities. The influence played by a number of effects, among them transverse shear deformation, initial geometric imperfections, the character of the in-plane boundary conditions and thickness ratio are studied and a series of conclusions are outlined. The influence played by the complete temperature field (i.e., the uniform through thickness and thickness-wise gradient) as compared to the one induced by only the uniform one, is discussed and the peculiarities of the resulting post-buckling behaviors are enlightened.

  20. Monte Carlo simulation-based feasibility study of novel indirect flat panel detector system for removing scatter radiation.

    PubMed

    Yoon, Yongsu; Morishita, Junji; Park, MinSeok; Kim, Hyunji; Kim, Kihyun; Kim, Jungmin

    2016-01-01

    The purpose of this study is to investigate the feasibility of a novel indirect flat panel detector (FPD) system for removing scatter radiation. The substrate layer of our FPD system has a Pb net-like structure that matches the ineffective area and blocks the scatter radiation such that only primary X-rays reach the effective area on a thin-film transistor. To evaluate the performance of the proposed system, we used Monte Carlo simulations to derive the scatter fraction and contrast. The scatter fraction of the proposed system is lower than that of a parallel grid system, and the contrast is superior to that of a system without a grid. If the structure of the proposed FPD system is optimized with respect to the specifications of a specific detector, the purpose of the examination, and the energy range used, the FPD can be useful in diagnostic radiology.

  1. Performance of flat panel (AMLCD) units installed in the aft end of drug interdiction P-3s

    NASA Astrophysics Data System (ADS)

    Sola, Kenneth E.; Sankovic, Michael

    1997-07-01

    The US Navy is proactively upgrading its fleet of P-3 Maritime Patrol Aircraft to continue to meet current and near future challenges to national security. The traditional P-3 role of anti-submarine warfare, though retained, is being expanded to include anti-surface warfare, increased reconnaissance and surveillance, and other missions. As part of the overall improvement program, P-3 cockpit and tactical crewstations throughout the aircraft are being upgraded to improve crew performance. Flat panel display technology is replacing CRTs in five on-going crewstation improvements. This paper reports on one of them: the replacement of CRT displays in a prototype EO/IR crewstation with a suite of four color AMLCDs, one of which is configured with a surface acoustic wave touch overlay to serve as a programmable touch interface. This upgrade is already in service with the fleet.

  2. Computerized methods for determining respiratory phase on dynamic chest radiographs obtained by a dynamic flat-panel detector (FPD) system.

    PubMed

    Tanaka, Rie; Sanada, Shigeru; Kobayashi, Takeshi; Suzuki, Masayuki; Matsui, Takeshi; Matsui, Osamu

    2006-03-01

    Chest radiography using a dynamic flat-panel detector with a large field of view can provide sequential chest radiographs during respiration. These images provide information regarding respiratory kinetics, which is effective for diagnosis of pulmonary diseases. For valid analysis of respiratory kinetics in diagnosis of pulmonary diseases, it is crucial to determine the association between the kinetics and respiratory phase. We developed four methods to determine the respiratory phase based on image information associated with respiration and compared the results in dynamic chest radiographs of 37 subjects. Here, the properties of each method and future tasks are discussed. The method based on the change in size of the lung gave the most stable results, and that based on the change in distance from the lung apex to the diaphragm was the most promising method for determining the respiratory phase.

  3. Dynamic defectoscopy with flat panel and CdTe Timepix X-ray detectors combined with an optical camera

    NASA Astrophysics Data System (ADS)

    Vavrik, D.; Fauler, A.; Fiederle, M.; Jandejsek, I.; Jakubek, M.; Turecek, D.; Zwerger, A.

    2013-04-01

    Damage of gradually loaded ductile materials involves a number of physical processes which are highly nonlinear and have different intensity and extent. Dynamic defectoscopy (i.e. defectoscopy of time changing damage processes) combining an X-ray/optical imaging system is proposed for online visualization and analysis of the complex behaviour of such materials. A large area flat panel detector with rather long read out time is used for overall observation of slow damage processes. On the other hand, a semiconductor CdTe Timepix detector with small active area allows following the rapid damage processes occurring in the final phase of specimen failure. Optical imaging of the specimen surface was utilized for analysing the specimen deformations.

  4. Cone-Beam CT with Flat-Panel-Detector Digital Angiography System: Early Experience in Abdominal Interventional Procedures

    SciTech Connect

    Hirota, Shozo Nakao, Norio; Yamamoto, Satoshi; Kobayashi, Kaoru; Maeda, Hiroaki; Ishikura, Reiichi; Miura, Koui; Sakamoto, Kiyoshi; Ueda, Ken; Baba, Rika

    2006-12-15

    We developed a cone-beam computed tomography (CBCT) system equipped with a large flat-panel detector. Data obtained by 200{sup o} rotation imaging are reconstructed by means of CBCT to generate three-dimensional images. We report the use of CBCT angiography using CBCT in 10 patients with 8 liver malignancies and 2 hypersplenisms during abdominal interventional procedures. CBCT was very useful for interventional radiologists to confirm a perfusion area of the artery catheter wedged on CT by injection of contrast media through the catheter tip, although the image quality was slightly degraded, scoring as 2.60 on average by streak artifacts. CBCT is space-saving because it does not require a CT system with a gantry, and it is also time-saving because it does not require the transfer of patients.

  5. A Rotatable Quality Control Phantom for Evaluating the Performance of Flat Panel Detectors in Imaging Moving Objects.

    PubMed

    Haga, Yoshihiro; Chida, Koichi; Inaba, Yohei; Kaga, Yuji; Meguro, Taiichiro; Zuguchi, Masayuki

    2016-02-01

    As the use of diagnostic X-ray equipment with flat panel detectors (FPDs) has increased, so has the importance of proper management of FPD systems. To ensure quality control (QC) of FPD system, an easy method for evaluating FPD imaging performance for both stationary and moving objects is required. Until now, simple rotatable QC phantoms have not been available for the easy evaluation of the performance (spatial resolution and dynamic range) of FPD in imaging moving objects. We developed a QC phantom for this purpose. It consists of three thicknesses of copper and a rotatable test pattern of piano wires of various diameters. Initial tests confirmed its stable performance. Our moving phantom is very useful for QC of FPD images of moving objects because it enables visual evaluation of image performance (spatial resolution and dynamic range) easily.

  6. Evaluation of imaging quality for flat-panel detector based low dose C-arm CT system

    SciTech Connect

    Seo, Chang-Woo; Cha, Bo Kyung; Jeon, Sungchae; Huh, Young

    2015-07-01

    The image quality associated with the extent of the angle of gantry rotation, the number of projection views, and the dose of X-ray radiation was investigated in flat-panel detector (FPD) based C-arm cone-beam computed tomography (CBCT) system for medical applications. A prototype CBCT system for the projection acquisition used the X-ray tube (A-132, Varian inc.) having rhenium-tungsten molybdenum target and flat panel a-Si X-ray detector (PaxScan 4030CB, Varian inc.) having a 397 x 298 mm active area with 388 μm pixel pitch and 1024 x 768 pixels in 2 by 2 binning mode. The performance comparison of X-ray imaging quality was carried out using the Feldkamp, Davis, and Kress (FDK) reconstruction algorithm between different conditions of projection acquisition. In this work, head-and-dental (75 kVp/20 mA) and chest (90 kVp/25 mA) phantoms were used to evaluate the image quality. The 361 (30 fps x 12 s) projection data during 360 deg. gantry rotation with 1 deg. interval for the 3D reconstruction were acquired. Parke weighting function were applied to handle redundant data and improve the reconstructed image quality in a mobile C-arm system with limited rotation angles. The reconstructed 3D images were investigated for comparison of qualitative image quality in terms of scan protocols (projection views, rotation angles and exposure dose). Furthermore, the performance evaluation in image quality will be investigated regarding X-ray dose and limited projection data for a FPD based mobile C-arm CBCT system. (authors)

  7. Performance quantification of a flat-panel imager in industrial mega-voltage X-ray imaging systems

    NASA Astrophysics Data System (ADS)

    Stritt, Carina; Plamondon, Mathieu; Hofmann, Jürgen; Flisch, Alexander; Sennhauser, Urs

    2017-03-01

    Active matrix flat-panel detectors have gained popularity amongst X-ray imaging systems due to their speed, resolution and high dynamic range. With appropriate shielding modern flat-panel imagers can even be used in high energy Computed Tomography (CT) systems of energies up to several mega-electronvolt (MeV). However, the performance of a digital detector is not independent of the rest of the radiographic system but depends on all other components of the system. Signal and noise transfer properties highly depend on all parameters of an imaging chain. This work focuses on quantifying the resolution capabilities and the noise in the signals of a MeV X-ray imaging system. The performance quantification is done by computing the modulation transfer function (MTF) using the standard edge method as well as the noise power spectrum (NPS) of the imaging system. We performed Monte Carlo (MC) simulations in order to understand the influence of scattered radiation on the measurements. A comparison of the horizontal and vertical MTF showed that the imaging behaviour of the detector is isotropic. Moreover, an additional investigation of the noise performance of the system showed that there is no measurable noise correlation present in the system. It was shown that the thickness of the edge device does not have a significant influence on the resulting system MTF. A rapid drop in the visibility could be observed resulting in a value of 1.2 line pairs per mm at 50% MTF. The visibility limit of line pair patterns was found to be at 2.3 line pairs per mm given by the 10% MTF value.

  8. Human health and ecological toxicity potentials due to heavy metal content in waste electronic devices with flat panel displays.

    PubMed

    Lim, Seong-Rin; Schoenung, Julie M

    2010-05-15

    Display devices such as cathode-ray tube (CRT) televisions and computer monitors are known to contain toxic substances and have consequently been banned from disposal in landfills in the State of California and elsewhere. New types of flat panel display (FPD) devices, millions of which are now purchased each year, also contain toxic substances, but have not previously been systematically studied and compared to assess the potential impact that could result from their ultimate disposal. In the current work, the focus is on the evaluation of end-of-life toxicity potential from the heavy metal content in select FPD devices with the intent to inform material selection and design-for-environment (DfE) decisions. Specifically, the metals antimony, arsenic, barium, beryllium, cadmium, chromium, cobalt, copper, lead, mercury, molybdenum, nickel, selenium, silver, vanadium, and zinc in plasma TVs, LCD (liquid crystal display) TVs, LCD computer monitors and laptop computers are considered. The human health and ecotoxicity potentials are evaluated through a life cycle assessment perspective by combining data on the respective heavy metal contents, the characterization factors in the U.S. EPA Tool for the Reduction and Assessment of Chemical and other environmental Impacts (TRACI), and a pathway and impact model. Principal contributors to the toxicity potentials are lead, arsenic, copper, and mercury. Although the heavy metal content in newer flat panel display devices creates less human health toxicity potential than that in CRTs, for ecological toxicity, the new devices are worse, especially because of the mercury in LCD TVs and the copper in plasma TVs.

  9. Signal and noise transfer properties of CMOS based active pixel flat panel imager coupled to structured CsI:Tl.

    PubMed

    Arvanitis, C D; Bohndiek, S E; Blakesley, J; Olivo, A; Speller, R D

    2009-01-01

    Complementary metal-oxide-semiconductors (CMOS) active pixel sensors can be optically coupled to CsI:Tl phosphors forming a indirect active pixel flat panel imager (APFPI) for high performance medical imaging. The aim of this work is to determine the x-ray imaging capabilities of CMOS-based APFPI and study the signal and noise transfer properties of CsI:Tl phosphors. Three different CsI:Tl phosphors from two different vendors have been used to produce three system configurations. The performance of each system configuration has been studied in terms of the modulation transfer function (MTF), noise power spectra, and detective quantum efficiency (DQE) in the mammographic energy range. A simple method to determine quantum limited systems in this energy range is also presented. In addition, with aid of monochromatic synchrotron radiation, the effect of iodine characteristic x-rays of the CsI:Tl on the MTF has been determined. A Monte Carlo simulation of the signal transfer properties of the imager is also presented in order to study the stages that degrade the spatial resolution of our current system. The effect of using substrate patterning during the growth of CsI:Tl columnar structure was also studied, along with the effect of CsI:Tl fixed pattern noise due to local variations in the scintillation light. CsI:Tl fixed pattern noise appears to limit the performance of our current system configurations. All the system configurations are quantum limited at 0.23 microC/kg with two of them having DQE (0) equal to 0.57. Active pixel flat panel imagers are shown to be digital x-ray imagers with almost constant DQE throughout a significant part of their dynamic range and in particular at very low exposures.

  10. Edge-Spread Functions Expected for Several Changes in a Commercial Flat-Panel System

    SciTech Connect

    Schach von Wittenau, A E

    2002-02-25

    The Bldg. 239 radiography facility uses a 9 MeV bremsstrahlung linac and a commercially available fiat-panel detector system. Ref. [1] discusses the facility in detail. Ref. [1] furthermore discusses the imaging quality of the fiat-panel system, and identifies several sources of image blur for the system in question. The maim'' contributors to the imaging blur are radiation scattered from the front cover of the detector housing, radiation scattered from the back cover of the detector housing, and radiation scattered from the aluminum plate that supports the amorphous-Si detector within the detector housing. The manufacturer of one such fiat-panel system seems willing to modify one of their products as requested, if such modifications may be made easily. Easy modifications would include making the detector housing thinner, decreasing the sizes of air gaps inside tile detector system, etc. Removing the aluminum support plate is considered to be a difficult modification. This memo reports the results of a set of Monte Carlo simulations that were performed to predict the changes in imaging quality, compared to that of the current system, if the detector is modified as suggested above. In particular, the edge-spread function (ESF) was calculated for each modification. ESFs were calculated for three photon energies: 100 keV, 450 keV, and 3 MeV. The results suggest that thinning and moving tile front and back covers of the detector housing should result in improved image quality for all of the photon energies considered. Interestingly, the results also suggest that removing the aluminum support plate would improve tim imaging performance at 100 keV and 450 keV, but that removing the plate has no additional benefit for imaging with 3 MeV photons.

  11. An Experimental Investigation of Sandwich Flat Panels Under Low Velocity Impact.

    DTIC Science & Technology

    1994-12-01

    adhesive also contribute to damage in some cases . xvii AN EXPERIMENTAL INVESTIGATION OF SANDWICH PANELS UNDER LOW VELOCITY IMPACT Introduction 1.1...properties of the adhesive and core were determined from the manufacturers specification. In the case of the core, the curves shown in Figure 2.4 and...In this case , the 90° layer is defined as the two 90* plies in the middle of the lay-up. The upper portion of the core beneath the impact site in the 0

  12. Hypervelocity Impact (HVI). Volume 3; WLE Small-Scale Fiberglass Panel Flat Target C-1

    NASA Technical Reports Server (NTRS)

    Gorman, Michael R.; Ziola, Steven M.

    2007-01-01

    During 2003 and 2004, the Johnson Space Center's White Sands Testing Facility in Las Cruces, New Mexico conducted hypervelocity impact tests on the space shuttle wing leading edge. Hypervelocity impact tests were conducted to determine if Micro-Meteoroid/Orbital Debris impacts could be reliably detected and located using simple passive ultrasonic methods. The objective of Target C-1 was to study hypervelocity impacts on the reinforced carbon-carbon (RCC) panels of the Wing Leading Edge. Fiberglass was used in place of RCC in the initial tests. Impact damage was detected using lightweight, low power instrumentation capable of being used in flight.

  13. Hypervelocity Impact (HVI). Volume 4; WLE Small-Scale Fiberglass Panel Flat Target C-2

    NASA Technical Reports Server (NTRS)

    Gorman, Michael R.; Ziola, Steven M.

    2007-01-01

    During 2003 and 2004, the Johnson Space Center's White Sands Testing Facility in Las Cruces, New Mexico conducted hypervelocity impact tests on the space shuttle wing leading edge. Hypervelocity impact tests were conducted to determine if Micro-Meteoroid/Orbital Debris impacts could be reliably detected and located using simple passive ultrasonic methods. The objective of Target C-2 was to study impacts through the reinforced carboncarbon (RCC) panels of the Wing Leading Edge. Fiberglass was used in place of RCC in the initial tests. Impact damage was detected using lightweight, low power instrumentation capable of being used in flight.

  14. Impact Testing on Reinforced Carbon-Carbon Flat Panels with Ice Projectiles for the Space Shuttle Return to Flight Program

    NASA Technical Reports Server (NTRS)

    Melis, Matthew E.; Revilock, Duane M.; Pereira, Michael J.; Lyle, Karen H.

    2009-01-01

    Following the tragedy of the Orbiter Columbia (STS-107) on February 1, 2003, a major effort commenced to develop a better understanding of debris impacts and their effect on the space shuttle subsystems. An initiative to develop and validate physics-based computer models to predict damage from such impacts was a fundamental component of this effort. To develop the models it was necessary to physically characterize reinforced carbon-carbon (RCC) along with ice and foam debris materials, which could shed on ascent and impact the orbiter RCC leading edges. The validated models enabled the launch system community to use the impact analysis software LS-DYNA (Livermore Software Technology Corp.) to predict damage by potential and actual impact events on the orbiter leading edge and nose cap thermal protection systems. Validation of the material models was done through a three-level approach: Level 1--fundamental tests to obtain independent static and dynamic constitutive model properties of materials of interest, Level 2--subcomponent impact tests to provide highly controlled impact test data for the correlation and validation of the models, and Level 3--full-scale orbiter leading-edge impact tests to establish the final level of confidence for the analysis methodology. This report discusses the Level 2 test program conducted in the NASA Glenn Research Center (GRC) Ballistic Impact Laboratory with ice projectile impact tests on flat RCC panels, and presents the data observed. The Level 2 testing consisted of 54 impact tests in the NASA GRC Ballistic Impact Laboratory on 6- by 6-in. and 6- by 12-in. flat plates of RCC and evaluated three types of debris projectiles: Single-crystal, polycrystal, and "soft" ice. These impact tests helped determine the level of damage generated in the RCC flat plates by each projectile and validated the use of the ice and RCC models for use in LS-DYNA.

  15. Advanced radiator concepts utilizing honeycomb panel heat pipes (stainless steel)

    NASA Astrophysics Data System (ADS)

    Fleischman, G. L.; Tanzer, H. J.

    1985-08-01

    The feasibility of fabricating and processing moderate temperature range heat pipes in a low mass honeycomb sandwich panel configuration for highly efficient radiator fins for the NASA space station was investigated. A variety of honeycomb panel facesheet and core-ribbon wick concepts were evaluated within constraints dictated by existing manufacturing technology and equipment. Concepts evaluated include: type of material, material and panel thicknesses, wick type and manufacturability, liquid and vapor communication among honeycomb cells, and liquid flow return from condenser to evaporator facesheet areas. In addition, the overall performance of the honeycomb panel heat pipe was evaluated analytically.

  16. Advanced radiator concepts utilizing honeycomb panel heat pipes (stainless steel)

    NASA Technical Reports Server (NTRS)

    Fleischman, G. L.; Tanzer, H. J.

    1985-01-01

    The feasibility of fabricating and processing moderate temperature range heat pipes in a low mass honeycomb sandwich panel configuration for highly efficient radiator fins for the NASA space station was investigated. A variety of honeycomb panel facesheet and core-ribbon wick concepts were evaluated within constraints dictated by existing manufacturing technology and equipment. Concepts evaluated include: type of material, material and panel thicknesses, wick type and manufacturability, liquid and vapor communication among honeycomb cells, and liquid flow return from condenser to evaporator facesheet areas. In addition, the overall performance of the honeycomb panel heat pipe was evaluated analytically.

  17. A low Z linac and flat panel imager: comparison with the conventional imaging approach

    NASA Astrophysics Data System (ADS)

    Roberts, D. A.; Hansen, V. N.; Niven, A. C.; Thompson, M. G.; Seco, J.; Evans, P. M.

    2008-11-01

    Experimental and Monte Carlo simulations were conducted for an Elekta Ltd Precise Treatment System linac fitted with a low Z insert of sufficient thickness to remove all primary electrons. A variety of amorphous silicon based panels employing different scintillators were modelled to determine their response to a variety of x-ray spectra and produce an optimized portal imaging system. This study has shown that in a low Z configuration the vast majority of x-rays are produced in the nickel electron window, and with a combination of a carbon insert and caesium iodide based XVI-panel, significant improvement in the object contrast was achieved. For thin, head and neck-type geometries, contrast is 4.62 times greater for 1.6 cm bone in 5.8 cm water than the standard 6 MV/iViewGT system. For thicker, pelvis-type geometries contrast increases by a factor of 1.3 for 1.6 cm of bone in 25.8 cm water. To obtain images with the same signal-to-noise ratio as the 6 MV/iViewGT system, dose reductions of a factor of 15 and 4.2 are possible for 5.8 cm and 25.8 cm phantoms respectively. This design has the advantage of being easily implemented on a standard linac and provides a portal image directly from the therapy beam aperture.

  18. SU-E-J-45: The Correlation Between CBCT Flat Panel Misalignment and 3D Image Guidance Accuracy

    SciTech Connect

    Kenton, O; Valdes, G; Yin, L; Teo, B; Brousmiche, S; Wikler, D

    2015-06-15

    Purpose To simulate the impact of CBCT flat panel misalignment on the image quality, the calculated correction vectors in 3D image guided proton therapy and to determine if these calibration errors can be caught in our QA process. Methods The X-ray source and detector geometrical calibration (flexmap) file of the CBCT system in the AdaPTinsight software (IBA proton therapy) was edited to induce known changes in the rotational and translational calibrations of the imaging panel. Translations of up to ±10 mm in the x, y and z directions (see supplemental) and rotational errors of up to ±3° were induced. The calibration files were then used to reconstruct the CBCT image of a pancreatic patient and CatPhan phantom. Correction vectors were calculated for the patient using the software’s auto match system and compared to baseline values. The CatPhan CBCT images were used for quantitative evaluation of image quality for each type of induced error. Results Translations of 1 to 3 mm in the x and y calibration resulted in corresponding correction vector errors of equal magnitude. Similar 10mm shifts were seen in the y-direction; however, in the x-direction, the image quality was too degraded for a match. These translational errors can be identified through differences in isocenter from orthogonal kV images taken during routine QA. Errors in the z-direction had no effect on the correction vector and image quality.Rotations of the imaging panel calibration resulted in corresponding correction vector rotations of the patient images. These rotations also resulted in degraded image quality which can be identified through quantitative image quality metrics. Conclusion Misalignment of CBCT geometry can lead to incorrect translational and rotational patient correction vectors. These errors can be identified through QA of the imaging isocenter as compared to orthogonal images combined with monitoring of CBCT image quality.

  19. Hydrometallurgical Recovery of Indium from Flat-Panel Displays of Spent Liquid Crystal Televisions

    NASA Astrophysics Data System (ADS)

    Inoue, Katsutoshi; Alam, Shafiq

    2015-02-01

    A recovery process for indium from waste liquid crystal display panels was developed on the basis of hydrometallurgical technology. The powdered sample was leached with 3 M HCl to extract its various metal constituents (indium, aluminum, tin, etc.). The mutual separation and subsequent recovery of the dissolved metals was achieved using two column adsorption tests: The first column was packed with a porous resin impregnated with Aliquat 336, a commercially available solvent extraction reagent based on a quaternary ammonium compound, and the resin contained in the second column was impregnated with Cyanex 923, also a commercially available solvent extraction reagent based on trialkylphosphine oxide. In the first column, tin, iron, and zinc were removed from the leach liquor. In the second column, only indium was selectively recovered. The metal ions trapped in these columns were eluted with 0.1 M H2SO4, yielding a solution purified indium solution with a concentration 10 times that of the feed solution.

  20. Comparison of a digital flat-panel x-ray image intensifier and conventional film-screen system for radiostereometric analysis (RSA)

    NASA Astrophysics Data System (ADS)

    Yuan, Xunhua; Drangova, Maria; Pollmann, Steve; Miron, Ricky; Bourne, Robert; Holdsworth, David W.

    2004-05-01

    In this paper, the accuracy and precision of RSA analysis using a GE InnovaTM 4100 digital flat panel and a Siemens Multistar x-ray image intensifier (XRII) were evaluated and compared with that of a conventional film-screen system, in order to explore the possibility of real-time kinematic and dynamic RSA study. A phantom, having two rigid body segments with no movement, was constructed and imaged by the digital flat panel, XRII and conventional screen-film systems, respectively. The acquired images were measured and motions were derived. The mean and standard deviation of the repeated results were analyzed to determine the accuracy and precision, respectively. Comparing all three axes, the lowest rotational accuracy and precision were 0.008 +/- 0.011°, 0.013 +/- 0.015° and 0.006 +/- 0.05° while the lowest translational accuracy and precision were 25 +/- 28 mm, 17 +/- 37 mm and 4 +/- 6 mm for the film-screen, XRII and digital flat panel, respectively. The evaluation of the accuracy and precision of the RSA in this study confirms its place as a highly accurate method. The study shows that both digital flat panel and XRII systems have potential application to the kinematics and dynamics joint study.

  1. A compact high resolution flat panel PET detector based on the new 4-side buttable MPPC for biomedical applications

    NASA Astrophysics Data System (ADS)

    Wang, Qiang; Wen, Jie; Ravindranath, Bosky; O`Sullivan, Andrew W.; Catherall, David; Li, Ke; Wei, Shouyi; Komarov, Sergey; Tai, Yuan-Chuan

    2015-09-01

    Compact high-resolution panel detectors using virtual pinhole (VP) PET geometry can be inserted into existing clinical or pre-clinical PET systems to improve regional spatial resolution and sensitivity. Here we describe a compact panel PET detector built using the new Though Silicon Via (TSV) multi-pixel photon counters (MPPC) detector. This insert provides high spatial resolution and good timing performance for multiple bio-medical applications. Because the TSV MPPC design eliminates wire bonding and has a package dimension which is very close to the MPPC's active area, it is 4-side buttable. The custom designed MPPC array (based on Hamamatsu S12641-PA-50(x)) used in the prototype is composed of 4×4 TSV-MPPC cells with a 4.46 mm pitch in both directions. The detector module has 16×16 lutetium yttrium oxyorthosilicate (LYSO) crystal array, with each crystal measuring 0.92×0.92×3 mm3 with 1.0 mm pitch. The outer diameter of the detector block is 16.8×16.8 mm2. Thirty-two such blocks will be arranged in a 4×8 array with 1 mm gaps to form a panel detector with detection area around 7 cm×14 cm in the full-size detector. The flood histogram acquired with 68Ge source showed excellent crystal separation capability with all 256 crystals clearly resolved. The detector module's mean, standard deviation, minimum (best) and maximum (worst) energy resolution were 10.19%, ±0.68%, 8.36% and 13.45% FWHM, respectively. The measured coincidence time resolution between the block detector and a fast reference detector (around 200 ps single photon timing resolution) was 0.95 ns. When tested with Siemens Cardinal electronics the performance of the detector blocks remain consistent. These results demonstrate that the TSV-MPPC is a promising photon sensor for use in a flat panel PET insert composed of many high resolution compact detector modules.

  2. A compact high resolution flat panel PET detector based on the new 4-side buttable MPPC for biomedical applications

    PubMed Central

    Wang, Qiang; Wen, Jie; Ravindranath, Bosky; O’Sullivan, Andrew W.; Catherall, David; Li, Ke; Wei, Shouyi; Komarov, Sergey; Tai, Yuan-Chuan

    2015-01-01

    Compact high-resolution panel detectors using virtual pinhole (VP) PET geometry can be inserted into existing clinical or pre-clinical PET systems to improve regional spatial resolution and sensitivity. Here we describe a compact panel PET detector built using the new Though Silicon Via (TSV) multi-pixel photon counters (MPPC) detector. This insert provides high spatial resolution and good timing performance for multiple bio-medical applications. Because the TSV MPPC design eliminates wire bonding and has a package dimension which is very close to the MPPC’s active area, it is 4-side buttable. The custom designed MPPC array (based on Hamamatsu S12641-PA-50(x)) used in the prototype is composed of 4 × 4 TSV-MPPC cells with a 4.46 mm pitch in both directions. The detector module has 16 × 16 lutetium yttrium oxyorthosilicate (LYSO) crystal array, with each crystal measuring 0.92 × 0.92 × 3 mm3 with 1.0 mm pitch. The outer diameter of the detector block is 16.8 × 16.8 mm2. Thirty-two such blocks will be arranged in a 4 × 8 array with 1 mm gaps to form a panel detector with detection area around 7 cm × 14 cm in the full-size detector. The flood histogram acquired with Ge-68 source showed excellent crystal separation capability with all 256 crystals clearly resolved. The detector module’s mean, standard deviation, minimum (best) and maximum (worst) energy resolution were 10.19%, +/−0.68%, 8.36% and 13.45% FWHM, respectively. The measured coincidence time resolution between the block detector and a fast reference detector (around 200 ps single photon timing resolution) was 0.95 ns. When tested with Siemens Cardinal electronics the performance of the detector blocks remain consistent. These results demonstrate that the TSV-MPPC is a promising photon sensor for use in a flat panel PET insert composed of many high resolution compact detector modules. PMID:26085702

  3. Advanced radiator concepts utilizing honeycomb panel heat pipes

    NASA Technical Reports Server (NTRS)

    Fleischman, G. L.; Peck, S. J.; Tanzer, H. J.

    1987-01-01

    The feasibility of fabricating and processing moderate temperature range vapor chamber type heat pipes in a low mass honeycomb panel configuration for highly efficient radiator fins for potential use on the space station was investigated. A variety of honeycomb panel facesheet and core-ribbon wick concepts were evaluated within constraints dictated by existing manufacturing technology and equipment. Concepts evaluated include type of material, material and panel thickness, wick type and manufacturability, liquid and vapor communication among honeycomb cells, and liquid flow return from condenser to evaporator facesheet areas. A thin-wall all-welded stainless steel design with methanol as the working fluid was the initial prototype unit. It was found that an aluminum panel could not be fabricated in the same manner as a stainless steel panel due to diffusion bonding and resistance welding considerations. Therefore, a formed and welded design was developed. The prototype consists of ten panels welded together into a large panel 122 by 24 by 0.15 in., with a heat rejection capability of 1000 watts and a fin efficiency of essentially 1.0.

  4. Noise, sampling, and the number of projections in cone-beam CT with a flat-panel detector

    SciTech Connect

    Zhao, Z.; Gang, G. J.; Siewerdsen, J. H.

    2014-06-15

    Purpose: To investigate the effect of the number of projection views on image noise in cone-beam CT (CBCT) with a flat-panel detector. Methods: This fairly fundamental consideration in CBCT system design and operation was addressed experimentally (using a phantom presenting a uniform medium as well as statistically motivated “clutter”) and theoretically (using a cascaded systems model describing CBCT noise) to elucidate the contributing factors of quantum noise (σ{sub Q}), electronic noise (σ{sub E}), and view aliasing (σ{sub view}). Analysis included investigation of the noise, noise-power spectrum, and modulation transfer function as a function of the number of projections (N{sub proj}), dose (D{sub tot}), and voxel size (b{sub vox}). Results: The results reveal a nonmonotonic relationship between image noise andN{sub proj} at fixed total dose: for the CBCT system considered, noise decreased with increasing N{sub proj} due to reduction of view sampling effects in the regime N{sub proj} <∼200, above which noise increased with N{sub proj} due to increased electronic noise. View sampling effects were shown to depend on the heterogeneity of the object in a direct analytical relationship to power-law anatomical clutter of the form κ/f {sup β}—and a general model of individual noise components (σ{sub Q}, σ{sub E}, and σ{sub view}) demonstrated agreement with measurements over a broad range in N{sub proj}, D{sub tot}, and b{sub vox}. Conclusions: The work elucidates fairly basic elements of CBCT noise in a manner that demonstrates the role of distinct noise components (viz., quantum, electronic, and view sampling noise). For configurations fairly typical of CBCT with a flat-panel detector (FPD), the analysis reveals a “sweet spot” (i.e., minimum noise) in the rangeN{sub proj} ∼ 250–350, nearly an order of magnitude lower in N{sub proj} than typical of multidetector CT, owing to the relatively high electronic noise in FPDs. The analysis

  5. Empirical binary tomography calibration (EBTC) for the precorrection of beam hardening and scatter for flat panel CT

    SciTech Connect

    Grimmer, Rainer; Kachelriess, Marc

    2011-04-15

    Purpose: Scatter and beam hardening are prominent artifacts in x-ray CT. Currently, there is no precorrection method that inherently accounts for tube voltage modulation and shaped prefiltration. Methods: A method for self-calibration based on binary tomography of homogeneous objects, which was proposed by B. Li et al. [''A novel beam hardening correction method for computed tomography,'' in Proceedings of the IEEE/ICME International Conference on Complex Medical Engineering CME 2007, pp. 891-895, 23-27 May 2007], has been generalized in order to use this information to preprocess scans of other, nonbinary objects, e.g., to reduce artifacts in medical CT applications. Further on, the method was extended to handle scatter besides beam hardening and to allow for detector pixel-specific and ray-specific precorrections. This implies that the empirical binary tomography calibration (EBTC) technique is sensitive to spectral effects as they are induced by the heel effect, by shaped prefiltration, or by scanners with tube voltage modulation. The presented method models the beam hardening correction by using a rational function, while the scatter component is modeled using the pep model of B. Ohnesorge et al. [''Efficient object scatter correction algorithm for third and fourth generation CT scanners,'' Eur. Radiol. 9(3), 563-569 (1999)]. A smoothness constraint is applied to the parameter space to regularize the underdetermined system of nonlinear equations. The parameters determined are then used to precorrect CT scans. Results: EBTC was evaluated using simulated data of a flat panel cone-beam CT scanner with tube voltage modulation and bow-tie prefiltration and using real data of a flat panel cone-beam CT scanner. In simulation studies, where the ground truth is known, the authors' correction model proved to be highly accurate and was able to reduce beam hardening by 97% and scatter by about 75%. Reconstructions of measured data showed significantly less artifacts than

  6. Flat panel detector-based cone beam computed tomography with a circle-plus-two-arcs data acquisition orbit: preliminary phantom study.

    PubMed

    Ning, Ruola; Tang, Xiangyang; Conover, David; Yu, Rongfeng

    2003-07-01

    Cone beam computed tomography (CBCT) has been investigated in the past two decades due to its potential advantages over a fan beam CT. These advantages include (a) great improvement in data acquisition efficiency, spatial resolution, and spatial resolution uniformity, (b) substantially better utilization of x-ray photons generated by the x-ray tube compared to a fan beam CT, and (c) significant advancement in clinical three-dimensional (3D) CT applications. However, most studies of CBCT in the past are focused on cone beam data acquisition theories and reconstruction algorithms. The recent development of x-ray flat panel detectors (FPD) has made CBCT imaging feasible and practical. This paper reports a newly built flat panel detector-based CBCT prototype scanner and presents the results of the preliminary evaluation of the prototype through a phantom study. The prototype consisted of an x-ray tube, a flat panel detector, a GE 8800 CT gantry, a patient table and a computer system. The prototype was constructed by modifying a GE 8800 CT gantry such that both a single-circle cone beam acquisition orbit and a circle-plus-two-arcs orbit can be achieved. With a circle-plus-two-arcs orbit, a complete set of cone beam projection data can be obtained, consisting of a set of circle projections and a set of arc projections. Using the prototype scanner, the set of circle projections were acquired by rotating the x-ray tube and the FPD together on the gantry, and the set of arc projections were obtained by tilting the gantry while the x-ray tube and detector were at the 12 and 6 o'clock positions, respectively. A filtered backprojection exact cone beam reconstruction algorithm based on a circle-plus-two-arcs orbit was used for cone beam reconstruction from both the circle and arc projections. The system was first characterized in terms of the linearity and dynamic range of the detector. Then the uniformity, spatial resolution and low contrast resolution were assessed using

  7. Thermomechanical postbuckling of geometrically imperfect anisotropic flat and doubly curved sandwich panels

    NASA Astrophysics Data System (ADS)

    Hause, Terry John

    Sandwich structures constitute basic components of advanced supersonic/hypersonic flight and launch vehicles. These advanced flight vehicles operate in hostile environments consisting of high temperature, moisture, and pressure fields. As a result, these structures are exposed to large lateral pressures, large compressive edge loads, and high temperature gradients which can create large stresses and strains within the structure and can produce the instability of the structure. This creates the need for a better understanding of the behavior of these structures under these complex loading conditions. Moreover, a better understanding of the load carrying capacity of sandwich structures constitutes an essential step towards a more rational design and exploitation of these constructions. In order to address these issues, a comprehensive geometrically non-linear theory of doubly curved sandwich structures constructed of anisotropic laminated face sheets with an orthotropic core under various loadings for simply supported edge conditions is developed. The effects of the radii of curvature, initial geometric imperfections, pressure, uniaxial compressive edge loads, biaxial edge loading consisting of compressive/tensile edge loads, end thermal loads will be analyzed. The effect of the structural tailoring of the facesheets upon the load carrying capacity of the structure under these various loading conditions are analyzed. In addition, the movability/immovability of the unloaded edges and the end-shortening are examined. To pursue this study, two different formulations of the theory are developed. One of these formulations is referred to as the mixed formulation, while the second formulation is referred to as the displacement formulation. Several results are presented encompassing buckling, postbuckling, and stress/strain analysis in conjunction with the application of the structural tailoring technique. The great effects of this technique are explored. Moreover

  8. Fabrication and evaluation of advanced titanium structural panels for supersonic cruise aircraft

    NASA Technical Reports Server (NTRS)

    Payne, L.

    1977-01-01

    Flightworthy primary structural panels were designed, fabricated, and tested to investigate two advanced fabrication methods for titanium alloys. Skin-stringer panels fabricated using the weldbraze process, and honeycomb-core sandwich panels fabricated using a diffusion bonding process, were designed to replace an existing integrally stiffened shear panel on the upper wing surface of the NASA YF-12 research aircraft. The investigation included ground testing and Mach 3 flight testing of full-scale panels, and laboratory testing of representative structural element specimens. Test results obtained on full-scale panels and structural element specimens indicate that both of the fabrication methods investigated are suitable for primary structural applications on future civil and military supersonic cruise aircraft.

  9. Design and fabrication of brazed Rene 41 honeycomb sandwich structural panels for advanced space transportation systems

    NASA Technical Reports Server (NTRS)

    Hepler, A. K.; Swegle, A. R.

    1981-01-01

    The design and fabrication of two large brazed Rene 41 honeycomb panels, the establishment of a test plan, the design and fabrication of a test fixture to subject the panels to cyclic thermal gradients and mechanical loads equivalent to those imposed on an advanced space transportation vehicle during its boost and entry trajectories are discussed. The panels will be supported at four points, creating three spans. The outer spans are 45.7 cm (18 in.) and the center span 76.2 cm (30 in). Specimen width is 30.5 cm (12 in.). The panels were primarily designed by boost conditions simulated by subjecting the panels to liquid nitrogen, 77K (-320 F) on one side and 455K (360 F) on the other side and by mechanically imposing loads representing vehicle fuel pressure loads. Entry conditions were simulated by radiant heating to 1034K (1400 F). The test program subjected the panels to 500 boost thermal conditions. Results are presented.

  10. Analysis of a free-running synchronization artifact correction for MV-imaging with aSi:H flat panels

    SciTech Connect

    Mooslechner, Michaela; Mitterlechner, Bernhard; Weichenberger, Harald; Sedlmayer, Felix; Deutschmann, Heinz; Huber, Stefan

    2013-03-15

    Purpose: Solid state flat panel electronic portal imaging devices (EPIDs) are widely used for megavolt (MV) photon imaging applications in radiotherapy. In addition to their original purpose in patient position verification, they are convenient to use in quality assurance and dosimetry to verify beam geometry and dose deposition or to perform linear accelerator (linac) calibration procedures. However, native image frames from amorphous silicon (aSi:H) detectors show a range of artifacts which have to be eliminated by proper correction algorithms. When a panel is operated in free-running frame acquisition mode, moving vertical stripes (periodic synchronization artifacts) are a disturbing feature in image frames. Especially for applications in volumetric intensity modulated arc therapy (VMAT) or motion tracking, the synchronization (sync) artifacts are the limiting factor for potential and accuracy since they become even worse at higher frame rates and at lower dose rates, i.e., linac pulse repetition frequencies (PRFs). Methods: The authors introduced a synchronization correction method which is based on a theoretical model describing the interferences of the panel's readout clocking with the linac's dose pulsing. Depending on the applied PRF, a certain number of dose pulses is captured per frame which is readout columnwise, sequentially. The interference of the PRF with the panel readout is responsible for the period and the different gray value levels of the sync stripes, which can be calculated analytically. Sync artifacts can then be eliminated multiplicatively in precorrected frames without additional information about radiation pulse timing. Results: For the analysis, three aSi:H EPIDs of various types were investigated with 6 and 15 MV photon beams at varying PRFs of 25, 50, 100, 200, and 400 pulses per second. Applying the sync correction at panels with gadolinium oxysulfide scintillators improved single frame flood field image quality drastically

  11. Small animal imaging using a flat panel detector-based cone beam computed tomography (FPD-CBCT) imaging system

    NASA Astrophysics Data System (ADS)

    Conover, David L.; Ning, Ruola; Yu, Yong; Lu, Xianghua; Wood, Ronald W.; Reeder, Jay E.; Johnson, Aimee M.

    2005-04-01

    Flat panel detector-based cone beam CT (FPD-CBCT) imaging system prototypes have been constructed based on modified clinical CT scanners (a modified GE 8800 CT system and a modified GE HighSpeed Advantage (HSA) spiral CT system) each with a Varian PaxScan 2520 imager. The functions of the electromechanical and radiographic subsystems of the CT system were controlled through specially made hardware, software and data acquisition modules to perform animal cone beam CT studies. Small animal (mouse) imaging studies were performed to demonstrate the feasibility of an optimized CBCT imaging system to have the capability to perform longitudinal studies to monitor the progression of cancerous tumors or the efficacy of treatments. Radiographic parameters were optimized for fast (~10 second) scans of live mice to produce good reconstructed image quality with dose levels low enough to avoid any detectable radiation treatment to the animals. Specifically, organs in the pelvic region were clearly imaged and contrast studies showed the feasibility to visualize small vasculature and space-filling bladder tumors. In addition, prostate and mammary tumors were monitored in volume growth studies.

  12. The exact solution of shear-lag problems in flat panels and box beams assumed rigid in the transverse direction

    NASA Technical Reports Server (NTRS)

    Hildebrand, Francis B

    1943-01-01

    A mathematical procedure is herein developed for obtaining exact solutions of shear-lag problems in flat panels and box beams: the method is based on the assumption that the amount of stretching of the sheets in the direction perpendicular to the direction of essential normal stresses is negligible. Explicit solutions, including the treatment of cut-outs, are given for several cases and numerical results are presented in graphic and tabular form. The general theory is presented in a from which further solutions can be readily obtained. The extension of the theory to cover certain cases of non-uniform cross section is indicated. Although the solutions are obtained in terms of infinite series, the present developments differ from those previously given in that, in practical cases, the series usually converge so rapidly that sufficient accuracy is afforded by a small number of terms. Comparisons are made in several cases between the present results and the corresponding solutions obtained by approximate procedures devised by Reissner and by Kuhn and Chiarito.

  13. [Full-field digital mammography with amorphous silicon-based flat- panel detector: physical imaging characteristics and signal detection].

    PubMed

    Ideguchi, Tadamitsu; Higashida, Yoshiharu; Himuro, Kazuhiko; Ohki, Masafumi; Nakamura, Satoru; Yoshida, Akira; Takagi, Rie; Hatano, Hirohide; Kuwahara, Rie; Toyonaga, Makiko; Tanaka, Isamu; Toyofuku, Fukai

    2004-03-01

    The physical characteristics of a clinical amorphous silicon-based flat-panel imager for full-field digital mammography were investigated. Pre-sampled modulation transfer functions (MTF) were measured by using a slit method. Noise power spectra were determined for different input exposures by fast Fourier transform. The MTFs of full-field digital mammography systems showed significantly higher values than those of the computed radiography (CR) system. The full-field digital mammography system showed a lower noise level than that of the CR system under the same exposure conditions. Contrast detail analysis has been performed to compare the detectability of the full-field digital mammography system with that of the screen-film (Min-R 2000/Min-R 2000) system. The average contrast-detail curves of digital and film images were obtained from the results of observation. Image quality figures (IQF) were also calculated from the individual observer performance tests. The results indicated that the digital contrast-detail curves and IQF, on average, are superior to those of the screen-film system.

  14. Image performance of a new amorphous selenium flat panel x-ray detector designed for digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Cheung, L. K.; Jing, Z.; Bogdanovich, S.; Golden, K.; Robinson, S.; Beliaevskaia, E.; Parikh, S.

    2005-04-01

    The purpose of this work is to report the performance of an amorphous selenium (a-Se) based flat-panel x-ray imager under development for application in digital breast tomosynthesis. This detector is designed to perform both in the conventional Full Field Digital Mammography (FFDM) mode and the tomosynthesis mode. The large area 24 x 29 cm detector achieves rapid image acquisition rates of up to 4 frames per second with minimal trapped charge induced effects such as ghost or lag images of previously acquired objects. In this work, a new a-Se/TFT detector layer structure is evaluated. The design uses a top conductive layer in direct contact with the a-Se x-ray detection layer. The simple structure has few layers and minimal hole and electron trapping effects. Prototype detectors were built to investigate the basic image performance of this new a-Se/TFT detector. Image signal generation, image ghosting, image lag, and detector DQE were studied. For digital mammography applications, the residual image ghosting was less than 1% at 30 seconds elapsed time. DQE, measured at a field of 5.15 V/um, showed significantly higher values over previously reported data, especially at low exposure levels. For digital breast tomosynthesis, the image lag at dynamic readout rate was < 0.6 % at 0.5-second elapsed time. A prototype tomosynthesis system is being developed utilizing this new a-Se/TFT detector.

  15. Evaluation of bone substitute materials: comparison of flat-panel based volume CT to conventional multidetector CT.

    PubMed

    Sauerbier, Sebastian; Duttenhoefer, Fabian; Sachlos, Elefterios; Haberstroh, Jörg; Scheifele, Christian; Wrbas, Karl-Thomas; Voss, Pit Jacob; Veigel, Egle; Smedek, Jörg; Ganter, Philip; Tuna, Taskin; Gutwald, Ralf; Palmowski, Moritz

    2013-10-01

    Over the last decade tissue engineering has emerged as a key factor in bone regeneration within the field of cranio-maxillofacial surgery. Despite this in vivo analysis of tissue-engineered-constructs to monitor bone rehabilitation are difficult to conduct. Novel high-resolving flat-panel based volume CTs (fp-VCT) are increasingly used for imaging bone structures. This study compares the potential value of novel fp-VCT with conventional multidetector CT (MDCT) based on a sheep sinus floor elevation model. Calcium-hydroxyapatite reinforced collagen scaffolds were populated with autologous osteoblasts and implanted into sheep maxillary sinus. After 8, 16 and 24 weeks MDCT and fp-VCT scans were performed to investigate the volume of the augmented area; densities of cancellous and compact bone were assessed as comparative values. fp-VCT imaging resulted in higher spatial resolution, which was advantageous when separating closely related anatomical structures (i.e. trabecular and compact bone, biomaterials). Fp-VCT facilitated imaging of alterations occurring in test specimens over time. fp-VCTs therefore displayed high volume coverage, dynamic imaging potential and superior performance when investigating superfine bone structures and bone remodelling of biomaterials. Thus, fp-VCTs may be a suitable instrument for intraoperative imaging and future in vivo tissue-engineering studies.

  16. Development of CT and 3D-CT Using Flat Panel Detector Based Real-Time Digital Radiography System

    SciTech Connect

    Ravindran, V. R.; Sreelakshmi, C.; Vibin

    2008-09-26

    The application of Digital Radiography in the Nondestructive Evaluation (NDE) of space vehicle components is a recent development in India. A Real-time DR system based on amorphous silicon Flat Panel Detector has been developed for the NDE of solid rocket motors at Rocket Propellant Plant of VSSC in a few years back. The technique has been successfully established for the nondestructive evaluation of solid rocket motors. The DR images recorded for a few solid rocket specimens are presented in the paper. The Real-time DR system is capable of generating sufficient digital X-ray image data with object rotation for the CT image reconstruction. In this paper the indigenous development of CT imaging based on the Realtime DR system for solid rocket motor is presented. Studies are also carried out to generate 3D-CT image from a set of adjacent CT images of the rocket motor. The capability of revealing the spatial location and characterisation of defect is demonstrated by the CT and 3D-CT images generated.

  17. [Pulmonary functional diagnostic imaging using a dynamic flat-panel detector: comparison with findings in pulmonary scintigraphy].

    PubMed

    Tanaka, Rie; Sanada, Shigeru; Fujimura, Masaki; Yasui, Masahide; Tsuji, Shiro; Hayashi, Norio; Nanbu, Yuko; Matsui, Osamu

    2009-06-20

    Pulmonary ventilation and circulation dynamics are reflected on dynamic chest radiographs as changes in X-ray translucency,i.e., pixel values. The present study was performed to develop a pulmonary functional evaluation method based on the changes in pixel value, and to investigate the clinical usefulness of our method. Sequential chest radiographs of 20 subjects (abnormal,n=12; normal,n=8) during respiration were obtained with a dynamic flat-panel detector (FPD) system. The average pixel value in each local area was measured tracking the same area. To facilitate visual evaluation, the results were mapped on the original image using a grayscale in which small changes were shown in black and large changes were shown in white. In our clinical evaluation in comparison with a pulmonary scintigraphy, pulmonary ventilation disorder was indicated as a reduction of changes in pixel values. In many patients, there was a correlation between our result and a pulmonary scintigraphy (0.7

  18. Development of CT and 3D-CT Using Flat Panel Detector Based Real-Time Digital Radiography System

    NASA Astrophysics Data System (ADS)

    Ravindran, V. R.; Sreelakshmi, C.; Vibin, Vibin

    2008-09-01

    The application of Digital Radiography in the Nondestructive Evaluation (NDE) of space vehicle components is a recent development in India. A Real-time DR system based on amorphous silicon Flat Panel Detector has been developed for the NDE of solid rocket motors at Rocket Propellant Plant of VSSC in a few years back. The technique has been successfully established for the nondestructive evaluation of solid rocket motors. The DR images recorded for a few solid rocket specimens are presented in the paper. The Real-time DR system is capable of generating sufficient digital X-ray image data with object rotation for the CT image reconstruction. In this paper the indigenous development of CT imaging based on the Realtime DR system for solid rocket motor is presented. Studies are also carried out to generate 3D-CT image from a set of adjacent CT images of the rocket motor. The capability of revealing the spatial location and characterisation of defect is demonstrated by the CT and 3D-CT images generated.

  19. Aging of imaging properties of a CMOS flat-panel detector for dental cone-beam computed tomography

    NASA Astrophysics Data System (ADS)

    Kim, D. W.; Han, J. C.; Yun, S.; Kim, H. K.

    2017-01-01

    We have experimentally investigated the long-term stability of imaging properties of a flat-panel detector in conditions used for dental x-ray imaging. The detector consists of a CsI:Tl layer and CMOS photodiode pixel arrays. Aging simulations were carried out using an 80-kVp x-ray beam at an air-kerma rate of approximately 5 mGy s-1 at the entrance surface of the detector with a total air kerma of up to 0.6 kGy. Dark and flood-field images were periodically obtained during irradiation, and the mean signal and noise levels were evaluated for each image. We also evaluated the modulation-transfer function (MTF), noise-power spectrum (NPS), and detective quantum efficiency (DQE). The aging simulation showed a decrease in both the signal and noise of the gain-offset-corrected images, but there was negligible change in the signal-to-noise performance as a function of the accumulated dose. The gain-offset correction for analyzing images resulted in negligible changes in MTF, NPS, and DQE results over the total dose. Continuous x-ray exposure to a detector can cause degradation in the physical performance factors such the detector sensitivity, but linear analysis of the gain-offset-corrected images can assure integrity of the imaging properties of a detector during its lifetime.

  20. The performance of an amorphous silicon flat panel for neutron imaging at the PSI NEUTRA facility

    NASA Astrophysics Data System (ADS)

    Estermann, Mirko; Frei, Gabriel; Lehmann, Eberhard; Vontobel, Peter

    2005-04-01

    Commonly applied imaging methods in neutron radiography use a CCD camera in conjunction with a scintillator or imaging plates. CCDs and imaging plates have desirable properties concerning resolution, linearity, dynamic range and signal-to-noise ratio ( S/ N) but both techniques have the disadvantage of a slow read out and for the CCD camera, an additional disadvantage is the loss of light through the optical system. Amorphous silicon detectors, originally developed for medical and industrial X-ray imaging, generally do not have the above-mentioned disadvantages. These detectors have a much faster readout and, in comparison to the generally used crystalline silicon, can be put directly in the X-ray or neutron beam without being damaged. This type of detector also does not require any optical interface, minimizing possible light loss. The detector is operated at room temperature, which has some influence on the noise. Using the whole dynamic range with a low gain, results in a S/ N of up to 30, for normal applications, however, a S/ N of about 15-20 is typical. The main drawback of this imaging device is the dynamic range of only 12 bits and the relatively complicated operating system in which different operation modes can be chosen. In 2003, successful experiments were performed with this new device, but it is still in its fledgling stages and improvements from the manufacturer as well as the experience from the NEUTRA team will help to advance this technique for neutron imaging in a most efficient way.

  1. Dual-energy cardiac imaging: an image quality and dose comparison for a flat-panel detector and x-ray image intensifier

    NASA Astrophysics Data System (ADS)

    Ducote, Justin L.; Xu, Tong; Molloi, Sabee

    2007-01-01

    This study presents a comparison of dual-energy imaging with an x-ray image intensifier and flat-panel detector for cardiac imaging. It also investigates if the wide dynamic range of the flat-panel detector can improve dual-energy image quality while reducing patient dose. Experimental contrast-to-noise (CNR) measurements were carried out in addition to simulation studies. Patient entrance exposure and system tube loading were also recorded. The studied contrast objects were calcium and iodine. System performance was quantified with a figure-of-merit (FOM) defined as the image CNR2 over patient entrance exposure. The range of thickness studied was from 10 to 30 cm of Lucite (PMMA). Detector dose was initially set to 140 nGy (16 µR)/frame. The high-energy 120 kVp beam was filtered by an additional 0.8 mm silver filter. Keeping the same filament current, the kVp for the low-energy beam was adjusted as a function of thickness until 140 nGy was achieved. System performance was found to be similar for both systems, with the x-ray image intensifier performing better at lower thicknesses and the flat-panel detector performing better at higher thicknesses. This requirement of fixed detector entrance exposure was then relaxed and the kVp for the low-energy beam was allowed to vary while the mAs of the x-ray tube remained fixed to study changes in dual-energy image quality, patient dose and FOM with the flat-panel detector. It was found that as the kVp for the low-energy beam was reduced, system performance would rise until reaching a maximum while simultaneously lowering patient exposure. Suggested recommendations for optimal dual-energy imaging implementation are also provided.

  2. Dual-energy cardiac imaging: an image quality and dose comparison for a flat-panel detector and x-ray image intensifier.

    PubMed

    Ducote, Justin L; Xu, Tong; Molloi, Sabee

    2007-01-07

    This study presents a comparison of dual-energy imaging with an x-ray image intensifier and flat-panel detector for cardiac imaging. It also investigates if the wide dynamic range of the flat-panel detector can improve dual-energy image quality while reducing patient dose. Experimental contrast-to-noise (CNR) measurements were carried out in addition to simulation studies. Patient entrance exposure and system tube loading were also recorded. The studied contrast objects were calcium and iodine. System performance was quantified with a figure-of-merit (FOM) defined as the image CNR(2) over patient entrance exposure. The range of thickness studied was from 10 to 30 cm of Lucite (PMMA). Detector dose was initially set to 140 nGy (16 microR)/frame. The high-energy 120 kVp beam was filtered by an additional 0.8 mm silver filter. Keeping the same filament current, the kVp for the low-energy beam was adjusted as a function of thickness until 140 nGy was achieved. System performance was found to be similar for both systems, with the x-ray image intensifier performing better at lower thicknesses and the flat-panel detector performing better at higher thicknesses. This requirement of fixed detector entrance exposure was then relaxed and the kVp for the low-energy beam was allowed to vary while the mAs of the x-ray tube remained fixed to study changes in dual-energy image quality, patient dose and FOM with the flat-panel detector. It was found that as the kVp for the low-energy beam was reduced, system performance would rise until reaching a maximum while simultaneously lowering patient exposure. Suggested recommendations for optimal dual-energy imaging implementation are also provided.

  3. Prediction of Dynamic Stall Characteristics Using Advanced Nonlinear Panel Methods,

    DTIC Science & Technology

    This paper presents preliminary results of work in which a surface singularity panel method is being extended for modelling the dynamic interaction...between a separated wake and a surface undergoing an unsteady motion. The method combines the capabilities of an unsteady time-stepping code and a... technique for modelling extensive separation using free vortex sheets. Routines are developed for treating the dynamic interaction between the separated

  4. Gain and offset calibration reduces variation in exposure-dependent SNR among systems with identical digital flat-panel detectors

    SciTech Connect

    Willis, Charles E.; Vinogradskiy, Yevgeniy Y.; Lofton, Brad K.; White, R. Allen

    2011-07-15

    Purpose: The conditions under which vendor performance criteria for digital radiography systems are obtained do not adequately simulate the conditions of actual clinical imaging with respect to radiographic technique factors, scatter production, and scatter control. Therefore, the relationship between performance under ideal conditions and performance in clinical practice remains unclear. Using data from a large complement of systems in clinical use, the authors sought to develop a method to establish expected performance criteria for digital flat-panel radiography systems with respect to signal-to-noise ratio (SNR) versus detector exposure under clinical conditions for thoracic imaging. Methods: The authors made radiographic exposures of a patient-equivalent chest phantom at 125 kVp and 180 cm source-to-image distance. The mAs value was modified to produce exposures above and below the mAs delivered by automatic exposure control. Exposures measured free-in-air were corrected to the imaging plane by the inverse square law, by the attenuation factor of the phantom, and by the Bucky factor of the grid for the phantom, geometry, and kilovolt peak. SNR was evaluated as the ratio of the mean to the standard deviation (SD) of a region of interest automatically selected in the center of each unprocessed image. Data were acquired from 18 systems, 14 of which were tested both before and after gain and offset calibration. SNR as a function of detector exposure was interpolated using a double logarithmic function to stratify the data into groups of 0.2, 0.5, 1.0, 2.0, and 5.0 mR exposure (1.8, 4.5, 9.0, 18, and 45 {mu}Gy air KERMA) to the detector. Results: The mean SNR at each exposure interval after calibration exhibited linear dependence on the mean SNR before calibration (r{sup 2} = 0.9999). The dependence was greater than unity (m = 1.101 {+-} 0.006), and the difference from unity was statistically significant (p < 0.005). The SD of mean SNR after calibration also

  5. Flat-Panel Computed Tomography (DYNA-CT) in Neuroradiology. From High-Resolution Imaging of Implants to One-Stop-Shopping for Acute Stroke.

    PubMed

    Doerfler, A; Gölitz, P; Engelhorn, T; Kloska, S; Struffert, T

    2015-10-01

    Originally aimed at improving standard radiography by providing higher absorption efficiency and a wider dynamic range, flat-panel detector technology has meanwhile got widely accepted in the neuroradiological community. Especially flat-panel detector computed tomography (FD-CT) using rotational C-arm mounted flat-panel detector technology is capable of volumetric imaging with a high spatial resolution. By providing CT-like images of the brain within the angio suite, FD-CT is able to rapidly visualize hemorrhage and may thus improve complication management without the need of patient transfer. As "Angiographic CT" FD-CT may be helpful during many diagnostic and neurointerventional procedures and for noninvasive monitoring and follow-up. In addition, spinal interventions and high-resolution imaging of the temporal bone might also benefit from FD-CT. Finally, using novel dynamic perfusion and angiographic protocols, FD-CT may provide functional information on brain perfusion and vasculature with the potential to replace standard imaging in selected acute stroke patients.

  6. Investigation of the signal behavior at diagnostic energies of prototype, direct detection, active matrix, flat-panel imagers incorporating polycrystalline HgI2

    PubMed Central

    Du, Hong; El-Mohri, Youcef; Zhao, Qihua; Su, Zhong; Yamamoto, Jin; Wang, Yi

    2009-01-01

    Active matrix, flat-panel x-ray imagers based on a-Si:H thin film transistors offer many advantages and are widely utilized in medical imaging applications. Unfortunately, the detective quantum efficiency (DQE) of conventional flat-panel imagers incorporating scintillators or a-Se photoconductors is significantly limited by their relatively modest signal to noise ratio, particularly in applications involving low x-ray exposures or high spatial resolution. For this reason, polycrystalline HgI2 is of considerable interest by virtue of its low effective work function, high atomic number, and the possibility of large-area deposition. In this study, a detailed investigation of the properties of prototype, flat-panel arrays coated with two forms of this high-gain photoconductor are reported. Encouragingly, high x-ray sensitivity, low dark current, and spatial resolution close to the theoretical limits were observed from a number of prototypes. In addition, input-quantum-limited DQE performance was measured from one of the prototypes at relatively low exposures. However, high levels of charge trapping, lag, and polarization, as well as pixel-to-pixel variations in x-ray sensitivity are of concern. While the results of the current study are promising, further development will be required to realize prototypes exhibiting the characteristics necessary to allow practical implementation of this approach. PMID:18296765

  7. X-ray performance of a wafer-scale CMOS flat panel imager for applications in medical imaging and nondestructive testing

    NASA Astrophysics Data System (ADS)

    Cha, Bo Kyung; Jeon, Seongchae; Seo, Chang-Woo

    2016-09-01

    This paper presents a wafer-scale complementary metal-oxide semiconductor (CMOS)-based X-ray flat panel detector for medical imaging and nondestructive testing applications. In this study, our proposed X-ray CMOS flat panel imager has been fabricated by using a 0.35 μm 1-poly/4-metal CMOS process. The pixel size is 100 μm×100 μm and the pixel array format is 1200×1200 pixels, which provide a field-of-view (FOV) of 120mm×120 mm. The 14.3-bit extended counting analog-to digital converter (ADC) with built-in binning mode was used to reduce the area and simultaneously improve the image resolution. The different screens such as thallium-doped CsI (CsI:Tl) and terbium gadolinium oxysulfide (Gd2O2S:Tb) scintillators were used as conversion materials for X-rays to visible light photons. The X-ray imaging performance such as X-ray sensitivity as a function of X-ray exposure dose, spatial resolution, image lag and X-ray images of various objects were measured under practical medical and industrial application conditions. This paper results demonstrate that our prototype CMOS-based X-ray flat panel imager has the significant potential for medical imaging and non-destructive testing (NDT) applications with high-resolution and high speed rate.

  8. Novel Na(+) doped Alq3 hybrid materials for organic light-emitting diode (OLED) devices and flat panel displays.

    PubMed

    Bhagat, S A; Borghate, S V; Kalyani, N Thejo; Dhoble, S J

    2015-05-01

    Pure and Na(+) -doped Alq3 complexes were synthesized by a simple precipitation method at room temperature, maintaining a stoichiometric ratio. These complexes were characterized by X-ray diffraction, Fourier transform infrared (FTIR), UV/Vis absorption and photoluminescence (PL) spectra. The X-ray diffractogram exhibits well-resolved peaks, revealing the crystalline nature of the synthesized complexes, FTIR confirms the molecular structure and the completion of quinoline ring formation in the metal complex. UV/Vis absorption and PL spectra of sodium-doped Alq3 complexes exhibit high emission intensity in comparison with Alq3 phosphor, proving that when doped in Alq3 , Na(+) enhances PL emission intensity. The excitation spectra of the synthesized complexes lie in the range 242-457 nm when weak shoulders are also considered. Because the sharp excitation peak falls in the blue region of visible radiation, the complexes can be employed for blue chip excitation. The emission wavelength of all the synthesized complexes lies in the bluish green/green region ranging between 485 and 531 nm. The intensity of the emission wavelength was found to be elevated when Na(+) is doped into Alq3 . Because both the excitation and emission wavelengths fall in the visible region of electromagnetic radiation, these phosphors can also be employed to improve the power conversion efficiency of photovoltaic cells by using the solar spectral conversion principle. Thus, the synthesized phosphors can be used as bluish green/green light-emitting phosphors for organic light-emitting diodes, flat panel displays, solid-state lighting technology - a step towards the desire to reduce energy consumption and generate pollution free light.

  9. Quantitative kinetic analysis of lung nodules by temporal subtraction technique in dynamic chest radiography with a flat panel detector

    NASA Astrophysics Data System (ADS)

    Tsuchiya, Yuichiro; Kodera, Yoshie; Tanaka, Rie; Sanada, Shigeru

    2007-03-01

    Early detection and treatment of lung cancer is one of the most effective means to reduce cancer mortality; chest X-ray radiography has been widely used as a screening examination or health checkup. The new examination method and the development of computer analysis system allow obtaining respiratory kinetics by the use of flat panel detector (FPD), which is the expanded method of chest X-ray radiography. Through such changes functional evaluation of respiratory kinetics in chest has become available. Its introduction into clinical practice is expected in the future. In this study, we developed the computer analysis algorithm for the purpose of detecting lung nodules and evaluating quantitative kinetics. Breathing chest radiograph obtained by modified FPD was converted into 4 static images drawing the feature, by sequential temporal subtraction processing, morphologic enhancement processing, kinetic visualization processing, and lung region detection processing, after the breath synchronization process utilizing the diaphragmatic analysis of the vector movement. The artificial neural network used to analyze the density patterns detected the true nodules by analyzing these static images, and drew their kinetic tracks. For the algorithm performance and the evaluation of clinical effectiveness with 7 normal patients and simulated nodules, both showed sufficient detecting capability and kinetic imaging function without statistically significant difference. Our technique can quantitatively evaluate the kinetic range of nodules, and is effective in detecting a nodule on a breathing chest radiograph. Moreover, the application of this technique is expected to extend computer-aided diagnosis systems and facilitate the development of an automatic planning system for radiation therapy.

  10. Dual-energy technique for digital flat-panel detectors without x-ray tube voltage switching

    NASA Astrophysics Data System (ADS)

    Coello, Christopher S.; Dinten, Jean-Marc; Arques, Marc; Rohr, Pierre; Odet, Christophe

    2007-03-01

    Dual-energy imaging increases the possibility of pulmonary nodule detection by reducing the bone structure noise. The major problem of the dual-energy acquisition process with digital flat-panel detectors is the interval of time between low-energy (LE) exposure and high-energy (HE) exposure. Due to misregistration between LE and HE images, motion artifacts pollute the subtracted image. This paper presents a new acquisition approach for dual-energy imaging developed in order to reduce this inter-exposure time. The idea is to keep the tube voltage constant and to just switch a filter in front of the imaged object and thus to modulate the outgoing x-ray spectrum. The first part of this study presents how to optimize system parameters for the new acquisition protocol: source voltage, dynamic filtration before the patient, exposure time for LE and HE acquisition. The tube load is kept constant to focus the optimization study on the dose and the exposure time. A noise quality factor (NQF) and a spectral quality factor (SQF) are used as criteria for optimization. The new approach system is then compared to the state-of-the-art system with voltage switching between low and high energy. A filtering algorithm of dual energy acquisitions enabling a significant noise reduction is presented. Performance between its combination with the new acquisition protocol and the reference one are compared. For a limited noise quality factor, three times faster acquisition time is obtained using the new system. Noise reduction techniques improve the image SNR by 61% in the new system and only 32% in the reference system, without taking into account the impact of better registration on the dual-energy image quality.

  11. Nonlinear statistical reconstruction for flat-panel cone-beam CT with blur and correlated noise models

    NASA Astrophysics Data System (ADS)

    Tilley, Steven; Siewerdsen, Jeffrey H.; Zbijewski, Wojciech; Stayman, J. Webster

    2016-03-01

    Flat-panel cone-beam CT (FP-CBCT) is a promising imaging modality, partly due to its potential for high spatial resolution reconstructions in relatively compact scanners. Despite this potential, FP-CBCT can face difficulty resolving important fine scale structures (e.g, trabecular details in dedicated extremities scanners and microcalcifications in dedicated CBCT mammography). Model-based methods offer one opportunity to improve high-resolution performance without any hardware changes. Previous work, based on a linearized forward model, demonstrated improved performance when both system blur and spatial correlations characteristics of FP-CBCT systems are modeled. Unfortunately, the linearized model relies on a staged processing approach that complicates tuning parameter selection and can limit the finest achievable spatial resolution. In this work, we present an alternative scheme that leverages a full nonlinear forward model with both system blur and spatially correlated noise. A likelihood-based objective function is derived from this forward model and we derive an iterative optimization algorithm for its solution. The proposed approach is evaluated in simulation studies using a digital extremities phantom and resolution-noise trade-offs are quantitatively evaluated. The correlated nonlinear model outperformed both the uncorrelated nonlinear model and the staged linearized technique with up to a 86% reduction in variance at matched spatial resolution. Additionally, the nonlinear models could achieve finer spatial resolution (correlated: 0.10 mm, uncorrelated: 0.11 mm) than the linear correlated model (0.15 mm), and traditional FDK (0.40 mm). This suggests the proposed nonlinear approach may be an important tool in improving performance for high-resolution clinical applications.

  12. Determination of the detective quantum efficiency of a prototype, megavoltage indirect detection, active matrix flat-panel imager.

    PubMed

    El-Mohri, Y; Jee, K W; Antonuk, L E; Maolinbay, M; Zhao, Q

    2001-12-01

    After years of aggressive development, active matrix flat-panel imagers (AMFPIs) have recently become commercially available for radiotherapy imaging. In this paper we report on a comprehensive evaluation of the signal and noise performance of a large-area prototype AMFPI specifically developed for this application. The imager is based on an array of 512 x 512 pixels incorporating amorphous silicon photodiodes and thin-film transistors offering a 26 x 26 cm2 active area at a pixel pitch of 508 microm. This indirect detection array was coupled to various x-ray converters consisting of a commercial phosphor screen (Lanex Fast B, Lanex Regular, or Lanex Fine) and a 1 mm thick copper plate. Performance of the imager in terms of measured sensitivity, modulation transfer function (MTF), noise power spectra (NPS), and detective quantum efficiency (DQE) is reported at beam energies of 6 and 15 MV and at doses of 1 and 2 monitor units (MU). In addition, calculations of system performance (NPS, DQE) based on cascaded-system formalism were reported and compared to empirical results. In these calculations, the Swank factor and spatial energy distributions of secondary electrons within the converter were modeled by means of EGS4 Monte Carlo simulations. Measured MTFs of the system show a weak dependence on screen type (i.e., thickness), which is partially due to the spreading of secondary radiation. Measured DQE was found to be independent of dose for the Fast B screen, implying that the imager is input-quantum-limited at 1 MU, even at an extended source-to-detector distance of 200 cm. The maximum DQE obtained is around 1%--a limit imposed by the low detection efficiency of the converter. For thinner phosphor screens, the DQE is lower due to their lower detection efficiencies. Finally, for the Fast B screen, good agreement between calculated and measured DQE was observed.

  13. Nonlinear Statistical Reconstruction for Flat-Panel Cone-Beam CT with Blur and Correlated Noise Models

    PubMed Central

    Tilley, Steven; Siewerdsen, Jeffrey H.; Zbijewski, Wojciech; Stayman, J. Webster

    2016-01-01

    Flat-panel cone-beam CT (FP-CBCT) is a promising imaging modality, partly due to its potential for high spatial resolution reconstructions in relatively compact scanners. Despite this potential, FP-CBCT can face difficulty resolving important fine scale structures (e.g, trabecular details in dedicated extremities scanners and microcalcifications in dedicated CBCT mammography). Model-based methods offer one opportunity to improve high-resolution performance without any hardware changes. Previous work, based on a linearized forward model, demonstrated improved performance when both system blur and spatial correlations characteristics of FP-CBCT systems are modeled. Unfortunately, the linearized model relies on a staged processing approach that complicates tuning parameter selection and can limit the finest achievable spatial resolution. In this work, we present an alternative scheme that leverages a full nonlinear forward model with both system blur and spatially correlated noise. A likelihood-based objective function is derived from this forward model and we derive an iterative optimization algorithm for its solution. The proposed approach is evaluated in simulation studies using a digital extremities phantom and resolution-noise trade-offs are quantitatively evaluated. The correlated nonlinear model outperformed both the uncorrelated nonlinear model and the staged linearized technique with up to a 86% reduction in variance at matched spatial resolution. Additionally, the nonlinear models could achieve finer spatial resolution (correlated: 0.10 mm, uncorrelated: 0.11 mm) than the linear correlated model (0.15 mm), and traditional FDK (0.40 mm). This suggests the proposed nonlinear approach may be an important tool in improving performance for high-resolution clinical applications. PMID:27110051

  14. SU-D-12A-04: Investigation of a 2D Antiscatter Grid for Flat Panel Detectors

    SciTech Connect

    Altunbas, C; Kavanagh, B; Miften, M; Zhong, Y; Shaw, C

    2014-06-01

    Purpose: To improve CT number accuracy and contrast sensitivity, a novel 2D antiscatter grid (ASG) for flat panel detector (FPD) based CBCT imaging was evaluated. Experiments were performed to characterize the scatter rejection and contrast sensitivity performance of ASG. The reduction in primary transmission for various ASG geometries was also evaluated by a computational model. Methods: The 2D ASG design was based on multi-hole collimators used in Nuclear Medicine. It consisted of abutted hexagon shaped apertures with 2.5 mm pitch and 32 mm height, and separated by 0.25 mm thick lead septa. Scatter-to-primary ratio (SPR), contrast-to-noise ratio (CNR), and mean primary transmission were measured using a benchtop FPD/x-ray source system. Acrylic slabs of varying thicknesses were imaged with a contrast-detail phantom to measure CNR and SPR under different scatter conditions. Primary transmission was also measured by averaging pixel values in flood field images without the phantom. We additionally explored variation of primary transmission with pitch and septum thickness using a computational model of our ASG. Results: Our 2D ASG reduced the SPR from 3.3 to 0.12, and improved CNR by 50% in 20 cm thick slab phantom projections acquired at 120 kVp. While the measured primary transmission was 72.8%, our simulations show that primary transmission can be increased to 86% by reducing the septum thickness to 0.1 mm. Primary transmission further increases to 93% if septum thickness of 0.1 mm is used in conjunction with an increased pitch of 4 mm. Conclusion: The 2D ASG appears to be a promising scatter rejection device, offering both superior scatter rejection and improved contrast sensitivity. Though its lead footprint reduced primary transmission, our work shows that optimization of aperture pitch and septum thickness can significantly improve the primary transmission.

  15. 2013 Advanced Environmental Health/Advanced Food Technology Standing Review Panel Final Report

    NASA Technical Reports Server (NTRS)

    Steinberg, Susan

    2014-01-01

    The 2013 Advanced Environmental Health/Advanced Food Technology (AEH/AFT) Standing Review Panel (from here on referred to as the SRP) participated in a WebEx/teleconference with members of the Space Human Factors and Habitability (SHFH) Element, representatives from the Human Research Program (HRP), and NASA Headquarters on November 22, 2013 (list of participants is in Section IX of this report). The SRP reviewed the updated research plans for the Risk of Adverse Health Effects Due to Alterations in Host-Microorganism Interactions (Host Microbe Risk) and the Risk of Performance Decrement and Crew Illness Due to an Inadequate Food System (Food Risk). The SRP also received a status update on the Risk of Adverse Health Effects of Exposure to Dust and Volatiles during Exploration of Celestial Bodies (Dust Risk). Overall, the SRP was impressed with the strong research plans presented by the scientists and staff associated with the SHFH Element. The SRP also thought that the updated research plans were thorough, well organized, and presented in a comprehensive manner. The SRP agrees with the changes made to the Host Microbe Risk and Food Risk portfolios and thinks that the targets for Gap closure are appropriate.

  16. Charts for the minimum-weight design of 24s-t aluminum-alloy flat compression panels with longitudinal z-section stiffeners

    NASA Technical Reports Server (NTRS)

    Schuette, Evan H

    1945-01-01

    Design charts are developed for 24s-t aluminum-alloy flat compression panels with longitudinal z-section stiffeners. These charts make possible the design of the lightest panels of this type for a wide range of design requirements. Examples of the use of the charts are given and it is pointed out on the basis of these examples that, over a wide range of design conditions, the maintenance of buckle-free surfaces does not conflict with the achievement of high structural efficiency. The achievement of the maximum possible structural efficiency with 24s-t aluminum-alloy panels, however, requires closer stiffener spacings than those now in common use.

  17. Performance of a static-anode/flat-panel x-ray fluoroscopy system in a diagnostic strength magnetic field: a truly hybrid x-ray/MR imaging system.

    PubMed

    Fahrig, R; Wen, Z; Ganguly, A; DeCrescenzo, G; Rowlands, J A; Stevens, G M; Saunders, R F; Pelc, N J

    2005-06-01

    Minimally invasive procedures are increasing in variety and frequency, facilitated by advances in imaging technology. Our hybrid imaging system (GE Apollo flat panel, custom Brand x-ray static anode x-ray tube, GE Lunar high-frequency power supply and 0.5 T Signa SP) provides both x-ray and MR imaging capability to guide complex procedures without requiring motion of the patient between two distant gantries. The performance of the x-ray tube in this closely integrated system was evaluated by modeling and measuring both the response of the filament to an externally applied field and the behavior of the electron beam for field strengths and geometries of interest. The performance of the detector was assessed by measuring the slanted-edge modulation transfer function (MTF) and when placed at zero field and at 0.5 T. Measured resonant frequencies of filaments can be approximated using a modified vibrating beam model, and were at frequencies well below the 25 kHz frequency of our generator for our filament geometry. The amplitude of vibration was not sufficient to cause shorting of the filament during operation within the magnetic field. A simple model of electrons in uniform electric and magnetic fields can be used to estimate the deflection of the electron beam on the anode for the fields of interest between 0.2 and 0.5 T. The MTF measured at the detector and the DQE showed no significant difference inside and outside of the magnetic field. With the proper modifications, an x-ray system can be fully integrated with a MR system, with minimal loss of image quality. Any x-ray tube can be assessed for compatibility when placed at a particular location within the field using the models. We have also concluded that a-Si electronics are robust against magnetic fields. Detailed knowledge of the x-ray system installation is required to provide estimates of system operation.

  18. SU-E-I-49: Simulation Study for Removing Scatter Radiation in Cesium-Iodine Based Flat Panel Detector System

    SciTech Connect

    Yoon, Y; Park, M; Kim, H; Kim, K; Kim, J; Morishita, J

    2015-06-15

    Purpose: This study aims to identify the feasibility of a novel cesium-iodine (CsI)-based flat-panel detector (FPD) for removing scatter radiation in diagnostic radiology. Methods: The indirect FPD comprises three layers: a substrate, scintillation, and thin-film-transistor (TFT) layer. The TFT layer has a matrix structure with pixels. There are ineffective dimensions on the TFT layer, such as the voltage and data lines; therefore, we devised a new FPD system having net-like lead in the substrate layer, matching the ineffective area, to block the scatter radiation so that only primary X-rays could reach the effective dimension.To evaluate the performance of this new FPD system, we conducted a Monte Carlo simulation using MCNPX 2.6.0 software. Scatter fractions (SFs) were acquired using no grid, a parallel grid (8:1 grid ratio), and the new system, and the performances were compared.Two systems having different thicknesses of lead in the substrate layer—10 and 20μm—were simulated. Additionally, we examined the effects of different pixel sizes (153×153 and 163×163μm) on the image quality, while keeping the effective area of pixels constant (143×143μm). Results: In case of 10μm lead, the SFs of the new system (∼11%) were lower than those of the other system (∼27% with no grid, ∼16% with parallel grid) at 40kV. However, as the tube voltage increased, the SF of new system (∼19%) was higher than that of parallel grid (∼18%) at 120kV. In the case of 20μm lead, the SFs of the new system were lower than those of the other systems at all ranges of the tube voltage (40–120kV). Conclusion: The novel CsI-based FPD system for removing scatter radiation is feasible for improving the image contrast but must be optimized with respect to the lead thickness, considering the system’s purposes and the ranges of the tube voltage in diagnostic radiology. This study was supported by a grant(K1422651) from Institute of Health Science, Korea University.

  19. A ghost story: spatio-temporal response characteristics of an indirect-detection flat-panel imager.

    PubMed

    Siewerdsen, J H; Jaffray, D A

    1999-08-01

    Spatial and temporal imaging characteristics of an amorphous silicon flat-panel imager (FPI) were investigated in terms relevant to the application of such devices in cone-beam computed tomography (CBCT) and other x-ray imaging modalities, including general radiography, fluoroscopy, mammography, radiotherapy portal imaging, and nondestructive testing. Specifically, issues of image lag (including the magnitude, spatial uniformity, temporal-frequency characteristics, and dependence upon exposure and frame time) and long-term image persistence ("ghosts") were investigated. As part of the basic characterization of the FPI, pixel dark signal and noise (magnitude, temporal stability, and spatial uniformity) as well as radiation response (signal size, linearity, gain, and reciprocity) were also measured. Image lag was analyzed as a function of frame time and incident exposure. First-frame lag (i.e., the relative residual signal in the first frame following readout of an exposure) was approximately 2-10%, depending upon incident exposure and was spatially nonuniform to a slight degree across the FPI; second-, third-, and fourth-frame lag were approximately 0.7%, 0.4%, and 0.3%, respectively (at 25% sensor saturation). Image lag was also analyzed in terms of the temporal-frequency-dependent transfer function derived from the radiation response, allowing a quantitative description of system components contributing to lag. Finally, the contrast of objects as a function of time following an exposure was measured in order to examine long-term image persistence ("ghosts"). Ghosts were found to persist up to 30 min or longer, depending upon the exposure and frame time. Two means of reducing the apparent contrast of ghost images were tested: (i) rapid scanning of the FPI at maximum frame rate, and (ii) flood-field exposure of the FPI; neither was entirely satisfactory. These results pose important considerations for application of FPIs in CBCT as well as other x-ray imaging

  20. 2015 Advanced Environmental Health/Advanced Food Technology Standing Review Panel

    NASA Technical Reports Server (NTRS)

    Steinberg, Susan

    2015-01-01

    The 2015 Advanced Environmental Health/Advanced Food Technology (AEH/AFT) Standing Review Panel (from here on referred to as the SRP) met for a site visit in Houston, TX on December 14 - 15, 2015. The SRP met with representatives from the Space Human Factors and Habitability (SHFH) Element and members of the Human Research Program (HRP) to review the updated research plans for the Risk of Adverse Health Effects Due to Host-Microorganism Interactions (MicroHost Risk) and the Risk of Performance Decrement and Crew Illness due to an Inadequate Food System (Food Risk). During the meeting, the SRP also met with the vehicle engineers to discuss possible food storage options. The SRP would like to commend Dr. Oubre and Dr. Douglas for their detailed presentations, as well the frank, refreshing, and comprehensive engineering presentation. This gave much needed perspective to the food storage issues and reassured the committee about NASA's approach to the problem. In terms of critiques, the SRP remains unconvinced about the rationale for probiotic use other than for specific applications supported by the literature. It is not clear what gap or problem is being addressed by the use of probiotics, and the rationale for their use needs to be clearly rooted in the available literature. The SRP thinks that if low-Earth orbit is associated with immune system impairment, then there may additional risks linked with the use of probiotics. It is not clear to the SRP how NASA will determine if probiotics are having their intended beneficial effect. A similar concern is raised as to what gaps or problems are being addressed by "functional foods". Mixed infections, rather than single species infections, which can augment severity of disease, also represent a significant concern. Overall, the SRP considers this to be a strong program that is well-organized, well-coordinated and generates valuable data.

  1. DQE(f) of an amorphous-silicon flat-panel x-ray detector: detector parameter influences and measurement methodology

    NASA Astrophysics Data System (ADS)

    Granfors, Paul R.; Aufrichtig, Richard

    2000-04-01

    We discuss how the frequency dependent detective quantum efficiency [DQE(f)] in a well-designed amorphous silicon flat panel detector is affected by several phenomena that reduce the DQE in other types of medical imaging detectors. The detector examined employs a CsI(Tl) scintillator and is designed for general diagnostic x-ray imaging applications. We consider DQE degradation due to incomplete x-ray absorption, secondary quantum noise, Swank factor, Lubberts effect, spatial variation in gain, noise aliasing, and additive system noise. The influences of detector design parameters on the frequency- and exposure-dependent DQE are also examined. We find that the DQE does not depend directly on MTF and that DQE is independent of exposure within the detector's operating range, except at the lowest exposures. Likewise the signal per absorbed x-ray, which contains the fill factor as one of several multiplicative components, does not affect DQE except at the lowest exposures. A methodology for determining DQE(f) from measurements of MTF(f), noise power spectrum (NPS), average signal, and x-ray exposure is presented. We find that it is important to incorporate several corrections in the NPS measurement procedure in order to obtain accurate results. These include corrections for lag, non-linearity, response variation from pixel to pixel, and use of a finite number of flat-field images. MTF, NPS, and DQE results are presented for a 41 X 41-cm2 flat panel detector designed for radiographic applications.

  2. High-performance low-noise 128-channel readout-integrated circuit for flat-panel x-ray detector systems

    NASA Astrophysics Data System (ADS)

    Beuville, Eric J.; Belding, Mark; Costello, Adrienne N.; Hansen, Randy; Petronio, Susan M.

    2004-05-01

    A silicon mixed-signal integrated circuit is needed to extract and process x-ray induced signals from a coated flat panel thin film transistor array (TFT) in order to generate a digital x-ray image. Indigo Systems Corporation has designed, fabricated, and tested such a readout integrated circuit (ROIC), the ISC9717. This off-the-shelf, high performance, low-noise, 128-channel device is fully programmable with a multistage pipelined architecture and a 9 to 14-bit programmable A/D converter per channel, making it suitable for numerous X-ray medical imaging applications. These include high-resolution radiography in single frame mode and fluoroscopy where high frame rates are required. The ISC9717 can be used with various flat panel arrays and solid-state detectors materials: Selenium (Se), Cesium Iodide (CsI), Silicon (Si), Amorphous Silicon, Gallium Arsenide (GaAs), and Cadmium Zinc Telluride (CdZnTe). The 80-micron pitch ROIC is designed to interface (wire bonding or flip-chip) along one or two sides of the x-ray panel, where ROICs are abutted vertically, each reading out charge from pixels multiplexed onto 128 horizontal read lines. The paper will present the design and test results of the ROIC, including the mechanical and electrical interface to a TFT array, system performance requirements, output multiplexing of the digital signals to an off-board processor, and characterization test results from fabricated arrays.

  3. Feasibility of real time dual-energy imaging based on a flat panel detector for coronary artery calcium quantification.

    PubMed

    Xu, Tong; Ducote, Justin L; Wong, Jerry T; Molloi, Sabee

    2006-06-01

    The feasibility of a real-time dual-energy imaging technique with dynamic filtration using a flat panel detector for quantifying coronary arterial calcium was evaluated. In this technique, the x-ray beam was switched at 15 Hz between 60 kVp and 120 kVp with the 120 kVp beam having an additional 0.8 mm silver filter. The performance of the dynamic filtration technique was compared with a static filtration technique (4 mm Al+0.2 mm Cu for both beams). The ability to quantify calcium mass was evaluated using calcified arterial vessel phantoms with 20-230 mg of hydroxylapatite. The vessel phantoms were imaged over a Lucite phantom and then an anthropomorphic chest phantom. The total thickness of Lucite phantom ranges from 13.5-26.5 cm to simulate patient thickness of 16-32 cm. The calcium mass was measured using a densitometric technique. The effective dose to patient was estimated from the measured entrance exposure. The effects of patient thickness on contrast-to-noise ratio (CNR), effective dose, and the precision of calcium mass quantification (i.e., the frame to frame variability) were studied. The effects of misregistration artifacts were also measured by shifting the vessel phantoms manually between low- and high-energy images. The results show that, with the same detector signal level, the dynamic filtration technique produced 70% higher calcium contrast-to-noise ratio with only 4% increase in patient dose as compared to the static filtration technique. At the same time, x-ray tube loading increased by 30% with dynamic filtration. The minimum detectability of calcium with anatomical background was measured to be 34 mg of hydroxyapatite. The precision in calcium mass measurement, determined from 16 repeated dual-energy images, ranges from 13 mg to 41 mg when the patient thickness increased from 16 to 32 cm. The CNR was found to decrease with the patient thickness linearly at a rate of (-7%/cm). The anatomic background produced measurement root-mean-square (RMS

  4. Feasibility of real time dual-energy imaging based on a flat panel detector for coronary artery calcium quantification

    SciTech Connect

    Xu Tong; Ducote, Justin L.; Wong, Jerry T.; Molloi, Sabee

    2006-06-15

    The feasibility of a real-time dual-energy imaging technique with dynamic filtration using a flat panel detector for quantifying coronary arterial calcium was evaluated. In this technique, the x-ray beam was switched at 15 Hz between 60 kVp and 120 kVp with the 120 kVp beam having an additional 0.8 mm silver filter. The performance of the dynamic filtration technique was compared with a static filtration technique (4 mm Al+0.2 mm Cu for both beams). The ability to quantify calcium mass was evaluated using calcified arterial vessel phantoms with 20-230 mg of hydroxylapatite. The vessel phantoms were imaged over a Lucite phantom and then an anthropomorphic chest phantom. The total thickness of Lucite phantom ranges from 13.5-26.5 cm to simulate patient thickness of 16-32 cm. The calcium mass was measured using a densitometric technique. The effective dose to patient was estimated from the measured entrance exposure. The effects of patient thickness on contrast-to-noise ratio (CNR), effective dose, and the precision of calcium mass quantification (i.e., the frame to frame variability) were studied. The effects of misregistration artifacts were also measured by shifting the vessel phantoms manually between low- and high-energy images. The results show that, with the same detector signal level, the dynamic filtration technique produced 70% higher calcium contrast-to-noise ratio with only 4% increase in patient dose as compared to the static filtration technique. At the same time, x-ray tube loading increased by 30% with dynamic filtration. The minimum detectability of calcium with anatomical background was measured to be 34 mg of hydroxyapatite. The precision in calcium mass measurement, determined from 16 repeated dual-energy images, ranges from 13 mg to 41 mg when the patient thickness increased from 16 to 32 cm. The CNR was found to decrease with the patient thickness linearly at a rate of (-7%/cm). The anatomic background produced measurement root-mean-square (RMS

  5. Performance Study of an aSi Flat Panel Detector for Fast Neutron Imaging of Nuclear Waste

    SciTech Connect

    Schumann, M.; Mauerhofer, E.; Engels, R.; Kemmerling, G.; Frank, M.; Havenith, A.; Kettler, J.; Klapdor-Kleingrothaus, T.; Schitthelm, O.

    2015-07-01

    Radioactive waste must be characterized to check its conformance for intermediate storage and final disposal according to national regulations. For the determination of radio-toxic and chemo-toxic contents of radioactive waste packages non-destructive analytical techniques are preferentially used. Fast neutron imaging is a promising technique to assay large and dense items providing, in complementarity to photon imaging, additional information on the presence of structures in radioactive waste packages. Therefore the feasibility of a compact Neutron Imaging System for Radioactive waste Analysis (NISRA) using 14 MeV neutrons is studied in a cooperation framework of Forschungszentrum Juelich GmbH, RWTH Aachen University and Siemens AG. However due to the low neutron emission of neutron generators in comparison to research reactors the challenging task resides in the development of an imaging detector with a high efficiency, a low sensitivity to gamma radiation and a resolution sufficient for the purpose. The setup is composed of a commercial D-T neutron generator (Genie16GT, Sodern) with a surrounding shielding made of polyethylene, which acts as a collimator and an amorphous silicon flat panel detector (aSi, 40 x 40 cm{sup 2}, XRD-1642, Perkin Elmer). Neutron detection is achieved using a general propose plastic scintillator (EJ-260, Eljen Technology) linked to the detector. The thermal noise of the photodiodes is reduced by employing an entrance window made of aluminium. Optimal gain and integration time for data acquisition are set by measuring the response of the detector to the radiation of a 500 MBq {sup 241}Am-source. Detector performance was studied by recording neutron radiography images of materials with various, but well known, chemical compositions, densities and dimensions (Al, C, Fe, Pb, W, concrete, polyethylene, 5 x 8 x 10 cm{sup 3}). To simulate gamma-ray emitting waste radiographs in presence of a gamma-ray sources ({sup 60}Co, {sup 137}Cs, {sup 241

  6. Dual-energy cone-beam CT with a flat-panel detector: Effect of reconstruction algorithm on material classification

    SciTech Connect

    Zbijewski, W. Gang, G. J.; Xu, J.; Wang, A. S.; Stayman, J. W.; Taguchi, K.; Carrino, J. A.; Siewerdsen, J. H.

    2014-02-15

    Purpose: Cone-beam CT (CBCT) with a flat-panel detector (FPD) is finding application in areas such as breast and musculoskeletal imaging, where dual-energy (DE) capabilities offer potential benefit. The authors investigate the accuracy of material classification in DE CBCT using filtered backprojection (FBP) and penalized likelihood (PL) reconstruction and optimize contrast-enhanced DE CBCT of the joints as a function of dose, material concentration, and detail size. Methods: Phantoms consisting of a 15 cm diameter water cylinder with solid calcium inserts (50–200 mg/ml, 3–28.4 mm diameter) and solid iodine inserts (2–10 mg/ml, 3–28.4 mm diameter), as well as a cadaveric knee with intra-articular injection of iodine were imaged on a CBCT bench with a Varian 4343 FPD. The low energy (LE) beam was 70 kVp (+0.2 mm Cu), and the high energy (HE) beam was 120 kVp (+0.2 mm Cu, +0.5 mm Ag). Total dose (LE+HE) was varied from 3.1 to 15.6 mGy with equal dose allocation. Image-based DE classification involved a nearest distance classifier in the space of LE versus HE attenuation values. Recognizing the differences in noise between LE and HE beams, the LE and HE data were differentially filtered (in FBP) or regularized (in PL). Both a quadratic (PLQ) and a total-variation penalty (PLTV) were investigated for PL. The performance of DE CBCT material discrimination was quantified in terms of voxelwise specificity, sensitivity, and accuracy. Results: Noise in the HE image was primarily responsible for classification errors within the contrast inserts, whereas noise in the LE image mainly influenced classification in the surrounding water. For inserts of diameter 28.4 mm, DE CBCT reconstructions were optimized to maximize the total combined accuracy across the range of calcium and iodine concentrations, yielding values of ∼88% for FBP and PLQ, and ∼95% for PLTV at 3.1 mGy total dose, increasing to ∼95% for FBP and PLQ, and ∼98% for PLTV at 15.6 mGy total dose. For a

  7. Endovascular therapy for advanced post-thrombotic syndrome: Proceedings from a multidisciplinary consensus panel

    PubMed Central

    Vedantham, Suresh; Kahn, Susan R; Goldhaber, Samuel Z; Comerota, Anthony J; Parpia, Sameer; Meleth, Sreelatha; Earp, Diane; Williams, Rick; Sista, Akhilesh K; Marston, William; Rathbun, Suman; Magnuson, Elizabeth A; Razavi, Mahmood K; Jaff, Michael R; Kearon, Clive

    2016-01-01

    Patients with advanced post-thrombotic syndrome (PTS) and chronic iliac vein obstruction suffer major physical limitations and impairment of health-related quality of life. Currently there is a lack of evidence-based treatment options for these patients. Early studies suggest that imaging-guided, catheter-based endovascular therapy can eliminate iliac vein obstruction and saphenous venous valvular reflux, resulting in reduced PTS severity; however, these observations have not been rigorously validated. A multidisciplinary expert panel meeting was convened to plan a multicenter randomized controlled clinical trial to evaluate endovascular therapy for the treatment of advanced PTS. This article summarizes the findings of the panel, and is expected to assist in developing a National Institutes of Health-sponsored clinical trial and other studies to improve the care of patients with advanced PTS. PMID:27247235

  8. Photometric Calibration of an EUV Flat Field Spectrometer at the Advanced Light Source

    SciTech Connect

    May, M; Lepson, J; Beiersdorfer, P; Thorn, D; Chen, H; Hey, D; Smith, A

    2002-07-03

    The photometric calibration of ail extreme ultraviolet flat field spectrometer has been done at the Advanced Light Source at LBNL. This spectrometer is used to record spectrum for atomic physics research from highly charged ions in plasmas created in the Livermore electron beam ion traps EBIT-I and SUPEREBIT. Two calibrations were done each with a different gold-coated grating, a 1200 {ell}/mm and a 2400 {ell}/mm, that covered 75-300{angstrom} and 15-160{angstrom}, respectively. The detector for this calibration was a back thinned CCD. The relative calibration was determined for several different incident angles for both gratings. Within the scatter of the data, the calibration was roughly insensitive to the incidence angle for the range of angles investigated.

  9. Preliminary performance of image quality for a low-dose C-arm CT system with a flat-panel detector

    NASA Astrophysics Data System (ADS)

    Kyung Cha, Bo; Seo, Chang-Woo; Yang, Keedong; Jeon, Seongchae; Huh, Young

    2015-06-01

    Digital flat panel imager (FPI)-based cone-beam computed tomography (CBCT) has been widely used in C-arm imaging for spine surgery and interventional procedures. The system provides real-time fluoroscopy with high spatial resolution and three-dimensional (3D) visualization of anatomical structure without the need for patient transportation in interventional suite. In this work, a prototype CBCT imaging platform with continuous single rotation about the gantry was developed by using a large-area flat-panel detector with amorphous Si-based thin film transistor matrix. The different 2D projection images were acquired during constant gantry velocity for reconstructed images at a tube voltage of 80-120 kVp, and different current (10-50 mA) conditions. Various scan protocols were applied to a chest phantom human by changing the number of projection images and scanning angles. The projections were then reconstructed into a volumetric data of sections by using a 3D reconstruction algorithm (e.g., filtered back projection). The preliminary quantitative X-ray performance of our CBCT system was investigated by using the American Association of Physicists in Medicine CT phantom in terms of spatial resolution, contrast resolution, and CT number linearity for mobile or fixed C-arm based CBCT application with limited rotational geometry. The novel results of the projection data with different scanning angles and angular increments in the orbital gantry platform were acquired and evaluated experimentally.

  10. High-quality 3D correction of ring and radiant artifacts in flat panel detector-based cone beam volume CT imaging.

    PubMed

    Anas, Emran Mohammad Abu; Kim, Jae Gon; Lee, Soo Yeol; Hasan, Md Kamrul

    2011-10-07

    The use of an x-ray flat panel detector is increasingly becoming popular in 3D cone beam volume CT machines. Due to the deficient semiconductor array manufacturing process, the cone beam projection data are often corrupted by different types of abnormalities, which cause severe ring and radiant artifacts in a cone beam reconstruction image, and as a result, the diagnostic image quality is degraded. In this paper, a novel technique is presented for the correction of error in the 2D cone beam projections due to abnormalities often observed in 2D x-ray flat panel detectors. Template images are derived from the responses of the detector pixels using their statistical properties and then an effective non-causal derivative-based detection algorithm in 2D space is presented for the detection of defective and mis-calibrated detector elements separately. An image inpainting-based 3D correction scheme is proposed for the estimation of responses of defective detector elements, and the responses of the mis-calibrated detector elements are corrected using the normalization technique. For real-time implementation, a simplification of the proposed off-line method is also suggested. Finally, the proposed algorithms are tested using different real cone beam volume CT images and the experimental results demonstrate that the proposed methods can effectively remove ring and radiant artifacts from cone beam volume CT images compared to other reported techniques in the literature.

  11. [Correlation between basic imaging properties and subjective evaluations of two digital radiographic X-ray systems based on direct-conversion flat panel detector].

    PubMed

    Sakaguchi, Taro; Katayama, Reiji; Morishita, Junji; Sakai, Shinji; Kuroki, Hidefumi; Ohkubo, Seiji; Maeda, Takashi; Hayabuchi, Naofumi

    2010-11-20

    The purpose of this study was to examine the correlation between the basic imaging properties of two digital radiographic X-ray systems with a direct conversion flat-panel detector and their image qualities, which were evaluated by the observer in hard copy and soft copy studies. The subjective image quality was evaluated and compared in terms of the low-contrast detectability and image sharpness in the two digital radiographic X-ray systems. We applied the radiographs of a contrast detail phantom to the evaluation of low-contrast detectability and analyzed the contrast detail diagrams. Finally, low-contrast detectability was evaluated by the image quality figure (IQF) calculated from the contrast detail diagrams. Also, the subjective image sharpness of human dry bones of two systems was examined and evaluated by the normalized-rank method. The results indicated that System A tended to provide superior subjective image quality compared to System B in both observer studies. We also found high correlations between IQFs and basic imaging properties, such as the noise power spectrum (NPS) and the noise equivalent quantum (NEQ). In conclusion, the low-contrast detectability of the two digital radiographic X-ray systems with a direct conversion flat-panel detector corresponded to the NPS and the NEQ in both outputs (soft copy and hard copy). On the other hand, the subjective image sharpness of human dry bones was affected by their noise properties.

  12. The Usefulness of Three-Dimensional Angiography with a Flat Panel Detector of Direct Conversion Type in a Transcatheter Arterial Chemoembolization Procedure for Hepatocellular Carcinoma: Initial Experience

    SciTech Connect

    Kakeda, Shingo Korogi, Yukunori; Hatakeyama, Yoshihisa; Ohnari, Norihiro; Oda, Nobuhiro; Nishino, Kazuyoshi; Miyamoto, Wataru

    2008-03-15

    The purpose of this study was to assess the usefulness of a three-dimensional (3D) angiography system using a flat panel detector of direct conversion type in treatments with subsegmental transcatheter arterial chemoembolization (TACE) for hepatocellular carcinomas (HCCs). Thirty-six consecutive patients who underwent hepatic angiography were prospectively examined. First, two radiologists evaluated the degree of visualization of the peripheral branches of the hepatic arteries on 3D digital subtraction angiography (DSA). Then the radiologists evaluated the visualization of tumor staining and feeding arteries in 25 patients (30 HCCs) who underwent subsegmental TACE. The two radiologists who performed the TACE assessed whether the additional information provided by 3D DSA was useful for treatments. In 34 (94.4%) of 36 patients, the subsegmental branches of the hepatic arteries were sufficiently visualized. The feeding arteries of HCCs were sufficiently visualized in 28 (93%) of 30 HCCs, whereas tumor stains were sufficiently visualized in 18 (60%). Maximum intensity projection images were significantly superior to volume recording images for visualization of the tumor staining and feeding arteries of HCCs. In 27 (90%) of 30 HCCs, 3D DSA provided additional useful information for subsegmental TACE. The high-quality 3D DSA with flat panel detector angiography system provided a precise vascular road map, which was useful for performing subsegmental TACE .of HCCs.

  13. Thermo-enhanced field emission from ZnO nanowires: Role of defects and application in a diode flat panel X-ray source

    NASA Astrophysics Data System (ADS)

    Zhang, Zhipeng; Chen, Daokun; Chen, Wenqing; Chen, Yicong; Song, Xiaomeng; Zhan, Runze; Deng, Shaozhi; Xu, Ningsheng; Chen, Jun

    2017-03-01

    A thermo-enhanced field emission phenomenon was observed from ZnO nanowires. The field emission current increased by almost two orders of magnitude under a constant applied electric field, and the turn-on field decreased from 6.04 MV/m to 5.0 MV/m when the temperature increased from 323 to 723 K. The Poole-Frenkel electron excitation from the defect-induced trapping centers to the conduction band under high electric fields is believed to be the primary cause of the observed phenomenon. The experimental results fit well with the proposed physical model. The field emission from ZnO nanowires with different defect concentrations further confirmed the role of defects. Using the thermo-enhanced field emission phenomenon, a diode flat panel X-ray source was demonstrated, for which the energy and dose can be separately tuned. The thermo-enhanced field emission phenomenon observed from ZnO nanowires could be an effective way to realize a large area flat panel multi-energy X-ray source.

  14. A novel potential source of β-carotene: Eustigmatos cf. polyphem (Eustigmatophyceae) and pilot β-carotene production in bubble column and flat panel photobioreactors.

    PubMed

    Li, Zhen; Ma, Xiaoqin; Li, Aifen; Zhang, Chengwu

    2012-08-01

    Carotenoids profile of the unicellular Eustigmatos cf. polyphem (Eustigmatophyceae) and β-carotene production of the microalga in bubble column and large flat panel bioreactors were studied. The microalga which contained β-carotene, violaxanthin and vaucheriaxanthin as the major carotenoids accumulated large amount of β-carotene. The β-carotene production of this microalga in the bubble column bioreactor was considerable, with the maximum intracellular β-carotene content reaching 60.76 mg g(-1), biomass reaching 9.2 g L(-1), and β-carotene yield up to 470.2 mg L(-1). The β-carotene productions in two large flat panel bioreactors were relatively lower, whereas over 100 mg β-carotene L(-1) was achieved. Besides, high light intensity helped to accumulate intracellular β-carotene and biomass. Deficient nitrate supply inhibited biomass growth, though it helped to accumulate β-carotene. Our results first proved that E. cf. polyphem was a potential source and producer of β-carotene, making it an interesting subject for further β-carotene study or commercial exploration.

  15. The use of modern electronic flat panel devices for image guided radiation therapy:. Image quality comparison, intra fraction motion monitoring and quality assurance applications

    NASA Astrophysics Data System (ADS)

    Nill, S.; Stützel, J.; Häring, P.; Oelfke, U.

    2008-06-01

    With modern radiotherapy delivery techniques like intensity modulated radiotherapy (IMRT) it is possible to delivery a more conformal dose distribution to the tumor while better sparing the organs at risk (OAR) compared to 3D conventional radiation therapy. Due to the theoretically high dose conformity achievable it is very important to know the exact position of the target volume during the treatment. With more and more modern linear accelerators equipped with imaging devices this is now almost possible. These imaging devices are using energies between 120kV and 6MV and therefore different detector systems are used but the vast majority is using amorphous silicon flat panel devices with different scintilator screens and build up materials. The technical details and the image quality of these systems are discussed and first results of the comparison are presented. In addition new methods to deal with motion management and quality assurance procedures are shortly discussed.

  16. Cone beam breast CT with a high pitch (75 μm), thick (500 μm) scintillator CMOS flat panel detector: Visibility of simulated microcalcifications

    SciTech Connect

    Shen, Youtao; Zhong, Yuncheng; Lai, Chao-Jen; Wang, Tianpeng; Shaw, Chris C.

    2013-10-15

    Purpose: To measure and investigate the improvement of microcalcification (MC) visibility in cone beam breast CT with a high pitch (75 μm), thick (500 μm) scintillator CMOS/CsI flat panel detector (Dexela 2923, Perkin Elmer).Methods: Aluminum wires and calcium carbonate grains of various sizes were embedded in a paraffin cylinder to simulate imaging of calcifications in a breast. Phantoms were imaged with a benchtop experimental cone beam CT system at various exposure levels. In addition to the Dexela detector, a high pitch (50 μm), thin (150 μm) scintillator CMOS/CsI flat panel detector (C7921CA-09, Hamamatsu Corporation, Hamamatsu City, Japan) and a widely used low pitch (194 μm), thick (600 μm) scintillator aSi/CsI flat panel detector (PaxScan 4030CB, Varian Medical Systems) were also used in scanning for comparison. The images were independently reviewed by six readers (imaging physicists). The MC visibility was quantified as the fraction of visible MCs and measured as a function of the estimated mean glandular dose (MGD) level for various MC sizes and detectors. The modulation transfer functions (MTFs) and detective quantum efficiencies (DQEs) were also measured and compared for the three detectors used.Results: The authors have demonstrated that the use of a high pitch (75 μm) CMOS detector coupled with a thick (500 μm) CsI scintillator helped make the smaller 150–160, 160–180, and 180–200 μm MC groups more visible at MGDs up to 10.8, 9, and 10.8 mGy, respectively. It also made the larger 200–212 and 212–224 μm MC groups more visible at MGDs up to 7.2 mGy. No performance improvement was observed for 224–250 μm or larger size groups. With the higher spatial resolution of the Dexela detector based system, the apparent dimensions and shapes of MCs were more accurately rendered. The results show that with the aforementioned detector, a 73% visibility could be achieved in imaging 160–180 μm MCs as compared to 28% visibility achieved by

  17. Model-based iterative reconstruction for flat-panel cone-beam CT with focal spot blur, detector blur, and correlated noise

    NASA Astrophysics Data System (ADS)

    Tilley, Steven, II; Siewerdsen, Jeffrey H.; Webster Stayman, J.

    2016-01-01

    While model-based reconstruction methods have been successfully applied to flat-panel cone-beam CT (FP-CBCT) systems, typical implementations ignore both spatial correlations in the projection data as well as system blurs due to the detector and focal spot in the x-ray source. In this work, we develop a forward model for flat-panel-based systems that includes blur and noise correlation associated with finite focal spot size and an indirect detector (e.g. scintillator). This forward model is used to develop a staged reconstruction framework where projection data are deconvolved and log-transformed, followed by a generalized least-squares reconstruction that utilizes a non-diagonal statistical weighting to account for the correlation that arises from the acquisition and data processing chain. We investigate the performance of this novel reconstruction approach in both simulated data and in CBCT test-bench data. In comparison to traditional filtered backprojection and model-based methods that ignore noise correlation, the proposed approach yields a superior noise-resolution tradeoff. For example, for a system with 0.34 mm FWHM scintillator blur and 0.70 FWHM focal spot blur, using the correlated noise model instead of an uncorrelated noise model increased resolution by 42% (with variance matched at 6.9  ×  10-8 mm-2). While this advantage holds across a wide range of systems with differing blur characteristics, the improvements are greatest for systems where source blur is larger than detector blur.

  18. Development of a cardiac evaluation method using a dynamic flat-panel detector (FPD) system: a feasibility study using a cardiac motion phantom.

    PubMed

    Tanaka, Rie; Sanada, Shigeru; Tsujioka, Katsumi; Matsui, Takeshi; Takata, Tadanori; Matsui, Osamu

    2008-01-01

    The purpose of this study is to investigate the feasibility of cardiac evaluation with a dynamic flat-panel detector (FPD), based on changes in pixel values during cardiac pumping. To investigate the feasibility of cardiac evaluation with a dynamic flat-panel detector (FPD), based on changes in pixel values during cardiac pumping. Sequential radiographs of a cardiac motion phantom and water-equivalent material step were obtained with an FPD system. Various combinations of cardiac output and heart rate were evaluated with and without contrast medium. The ventricular area and summation of pixel values in the ventricles were measured. The ejection fraction (EF) was calculated based on the rate of changes and then compared to EF obtained from computed tomography images. In addition, slight changes in pixel values were visualized by use of inter-frame subtraction and color-mapping. The result of a clinical case was examined according to cardiac physiology. There were strong correlations between EF and our results. There was no significant difference between the findings with and without contrast medium. When the heart rate was greater than 60 bpm, EF obtained with our method were underestimated. It is necessary for a patient to be examined at an imaging rate between 7.5 and 10 fps at least. In addition, a +/-1.2% change in pixel value was equivalent to a +/-10 mm change in the thickness of water. Color-mapping images were supported by cardiac physiology. Evaluating changes in pixel values on dynamic chest radiography with FPD has the potential to demonstrate cardiac function without contrast medium. Inter-frame subtraction and color-mapping are very useful for interpreting changes in pixel value as velocities of blood flow.

  19. Impact Testing on Reinforced Carbon-Carbon Flat Panels With BX-265 and PDL-1034 External Tank Foam for the Space Shuttle Return to Flight Program

    NASA Technical Reports Server (NTRS)

    Melis, Matthew E.; Revilock, Duane M.; Pereira, Michael J.; Lyle, Karen H.

    2009-01-01

    Following the tragedy of the Orbiter Columbia (STS-107) on February 1, 2003, a major effort commenced to develop a better understanding of debris impacts and their effect on the space shuttle subsystems. An initiative to develop and validate physics-based computer models to predict damage from such impacts was a fundamental component of this effort. To develop the models it was necessary to physically characterize reinforced carbon-carbon (RCC) along with ice and foam debris materials, which could shed on ascent and impact the orbiter RCC leading edges. The validated models enabled the launch system community to use the impact analysis software LS-DYNA (Livermore Software Technology Corp.) to predict damage by potential and actual impact events on the orbiter leading edge and nose cap thermal protection systems. Validation of the material models was done through a three-level approach: Level 1-fundamental tests to obtain independent static and dynamic constitutive model properties of materials of interest, Level 2-subcomponent impact tests to provide highly controlled impact test data for the correlation and validation of the models, and Level 3-full-scale orbiter leading-edge impact tests to establish the final level of confidence for the analysis methodology. This report discusses the Level 2 test program conducted in the NASA Glenn Research Center (GRC) Ballistic Impact Laboratory with external tank foam impact tests on flat RCC panels, and presents the data observed. The Level 2 testing consisted of 54 impact tests in the NASA GRC Ballistic Impact Laboratory on 6- by 6-in. and 6- by 12-in. flat plates of RCC and evaluated two types of debris projectiles: BX-265 and PDL-1034 external tank foam. These impact tests helped determine the level of damage generated in the RCC flat plates by each projectile and validated the use of the foam and RCC models for use in LS-DYNA.

  20. Learning guide for the terminal configured vehicle advanced guidance and control system mode select panel

    NASA Technical Reports Server (NTRS)

    Anderson, M. A.; Callahan, R.

    1981-01-01

    This learning guide is designed to assist pilots in taking the PLATO presimulator training course on the advanced guidance and control system mode select panel. The learning guide is divided into five sections. The first section, the introduction, presents the course goals, prerequisites, definition of PLATO activities, and a suggested approach to completing the course. The remaining four sections present the purpose, learning activities and summary of each lesson of the AGCS PLATO course, which consists of (1) AGCS introduction; (2) lower order modes; (3) higher order modes; and (4) an arrival route exercise.

  1. An advanced panel method for analysis of arbitrary configurations in unsteady subsonic flow

    NASA Technical Reports Server (NTRS)

    Dusto, A. R.; Epton, M. A.

    1980-01-01

    An advanced method is presented for solving the linear integral equations for subsonic unsteady flow in three dimensions. The method is applicable to flows about arbitrary, nonplanar boundary surfaces undergoing small amplitude harmonic oscillations about their steady mean locations. The problem is formulated with a wake model wherein unsteady vorticity can be convected by the steady mean component of flow. The geometric location of the unsteady source and doublet distributions can be located on the actual surfaces of thick bodies in their steady mean locations. The method is an outgrowth of a recently developed steady flow panel method and employs the linear source and quadratic doublet splines of that method.

  2. Performance of High-Efficiency Advanced Triple-Junction Solar Panels for the LILT Mission Dawn

    NASA Technical Reports Server (NTRS)

    Fatemi, Navid S.; Sharma, Surya; Buitrago, Oscar; Sharps, Paul R.; Blok, Ron; Kroon, Martin; Jalink, Cees; Harris, Robin; Stella, Paul; Distefano, Sal

    2005-01-01

    NASA's Discovery Mission Dawn is designed to (LILT) conditions. operate within the solar system's Asteroid belt, where the large distance from the sun creates a low-intensity, low-temperature (LILT) condition. To meet the mission power requirements under LlLT conditions, very high-efficiency multi-junction solar cells were selected to power the spacecraft to be built by Orbital Sciences Corporation (OSC) under contract with JPL. Emcore's InGaP/InGaAs/Ge advanced triple-junction (ATJ) solar cells, exhibiting an average air mass zero (AMO) efficiency of greater than 27.6% (one-sun, 28 C), were used to populate the solar panels [1]. The two solar array wings, to be built by Dutch Space, with 5 large- area panels each (total area of 36.4 sq. meters) are projected to produce between 10.3 kWe and 1.3 kWe of end-of life (EOL) power in the 1.0 to 3.0 AU range, respectively. The details of the solar panel design, testing and power analysis are presented.

  3. Comparison of Advanced SPF Die Technologies in the Forming of a Production Panel

    NASA Astrophysics Data System (ADS)

    Luo, Y.; Luckey, S. G.; Copple, W. B.; Friedman, P. A.

    2008-04-01

    Superplastic forming (SPF) is a manufacturing process that can facilitate increased use of aluminum in automobile body structures. Despite considerable advantages with regards to formability and tooling costs, the process has been mostly limited to low volume production due to relatively long cycle times and the need to use specially processed sheet alloys. To address these issues, advanced processes such as two stage gas forming (TSGF) and hot draw mechanical pre-forming (HDMP) have been developed. Advantages of these processes have been demonstrated on the forming of a complex dash panel part. Final thickness distribution and forming time on this part manufactured with these two processes were compared to that of the same panel produced with conventional SPF. The HDMP technology which combines hot stamping with SPF was found to have the capability of forming a complex shaped component with a superior thickness profile and faster forming cycle than that formed with a conventional single stage or two stage forming cycle. Additionally, the HDMP process proved to be a robust process with a wide temperature window and allowed for the forming of lower-cost, non-spf aluminum, and magnesium sheet alloys. Finally, analysis of the post-form microstructure indicated that there was essentially no cavitation in panels formed with the HDMP process and that material with a coarse grain structure could be successfully formed.

  4. Identifying locally advanced basal cell carcinoma eligible for treatment with vismodegib: an expert panel consensus.

    PubMed

    Peris, Ketty; Licitra, Lisa; Ascierto, Paolo A; Corvò, Renzo; Simonacci, Marco; Picciotto, Franco; Gualdi, Giulio; Pellacani, Giovanni; Santoro, Armando

    2015-01-01

    Basal cell carcinoma (BCC) is the most common skin cancer worldwide. Most occur on the head and neck, where cosmetic and functional outcomes are critical. BCC can be locally destructive if not diagnosed early and treated appropriately. Surgery is the treatment of choice for the majority of high-risk lesions. Aggressive, recurrent or unresectable tumors can be difficult to manage. Until recently, no approved systemic therapy was available for locally advanced or metastatic BCC inappropriate for surgery or radiotherapy. Vismodegib provides a systemic treatment option. However, a consensus definition of advanced BCC is lacking. A multidisciplinary panel with expertise in oncology, dermatology, dermatologic surgery and radiation oncology proposes a consensus definition based on published evidence and clinical experience.

  5. Advanced Fast Reactor - 100 (AFR-100) Report for the Technical Review Panel

    SciTech Connect

    Grandy, Christopher; Sienicki, James J.; Moisseytsev, Anton; Krajtl, Lubomir; Farmer, Mitchell T.; Kim, Taek K.; Middleton, B.

    2014-06-04

    This report is written to provide an overview of the Advanced Fast Reactor-100 in the requested format for a DOE technical review panel. This report was prepared with information that is responsive to the DOE Request for Information, DE-SOL-0003674 Advanced Reactor Concepts, dated February 27, 2012 from DOE’s Office of Nuclear Energy, Office of Nuclear Reactor Technologies. The document consists of two main sections. The first section is a summary of the AFR-100 design including the innovations that are incorporated into the design. The second section contains a series of tables that respond to the various questions requested of the reactor design team from the subject DOE RFI.

  6. Low-speed longitudinal aerodynamic characteristics of a flat-plate planform model of an advanced fighter configuration

    NASA Technical Reports Server (NTRS)

    Mcgrath, Brian E.; Neuhart, Dan H.; Gatlin, Gregory M.; Oneil, Pat

    1994-01-01

    A flat-plate wind tunnel model of an advanced fighter configuration was tested in the NASA LaRC Subsonic Basic Research Tunnel and the 16- by 24-inch Water Tunnel. The test objectives were to obtain and evaluate the low-speed longitudinal aerodynamic characteristics of a candidate configuration for the integration of several new innovative wing designs. The flat plate test allowed for the initial evaluation of the candidate planform and was designated as the baseline planform for the innovative wing design study. Low-speed longitudinal aerodynamic data were obtained over a range of freestream dynamic pressures from 7.5 psf to 30 psf (M = 0.07 to M = 0.14) and angles-of-attack from 0 to 40 deg. The aerodynamic data are presented in coefficient form for the lift, induced drag, and pitching moment. Flow-visualization results obtained were photographs of the flow pattern over the flat plate model in the water tunnel for angles-of-attack from 10 to 40 deg. The force and moment coefficients and the flow-visualization photographs showed the linear and nonlinear aerodynamic characteristics due to attached flow and vortical flow over the flat plate model. Comparison between experiment and linear theory showed good agreement for the lift and induced drag; however, the agreement was poor for the pitching moment.

  7. Hydrogen production by the engineered cyanobacterial strain Nostoc PCC 7120 ΔhupW examined in a flat panel photobioreactor system.

    PubMed

    Nyberg, Marcus; Heidorn, Thorsten; Lindblad, Peter

    2015-12-10

    Nitrogenase based hydrogen production was examined in a ΔhupW strain of the filamentous heterocystous cyanobacterium Nostoc PCC 7120, i.e., cells lacking the last step in the maturation system of the large subunit of the uptake hydrogenase and as a consequence with a non-functional uptake hydrogenase. The cells were grown in a developed flat panel photobioreactor system with 3.0L culture volume either aerobically (air) or anaerobically (Ar or 80% N2/20% Ar) and illuminated with a mixture of red and white LED. Aerobic growth of the ΔhupW strain of Nostoc PCC 7120 at 44μmolar photons m(-2)s(-1) PAR gave the highest hydrogen production of 0.7mL H2 L(-1)h(-1), 0.53mmol H2 mg chlorophyll a(-1)h(-1), and a light energy conversion efficiency of 1.2%. Anaerobic growth using 100% argon showed a maximal hydrogen production of 1.7mLL(-1)h(-1), 0.85mmol per mg chlorophyll a(-1) h(-1), and a light energy conversion efficiency of 2.7%. Altering between argon/N2 (20/80) and 100% argon phases resulted in a maximal hydrogen production at hour 128 (100% argon phase) with 6.2mL H2L(-1)h(-1), 0.71mL H2 mg chlorophyll a(-1)h(-1), and a light energy efficiency conversion of 4.0%. The highest buildup of hydrogen gas observed was 6.89% H2 (100% argon phase) of the total photobioreactor system with a maximal production of 4.85mL H2 L(-1)h(-1). The present study clearly demonstrates the potential to use purpose design cyanobacteria in developed flat panel photobioreactor systems for the direct production of the solar fuel hydrogen. Further improvements in the strain used, environmental conditions employed, and growth, production and collection systems used, are needed before a sustainable and economical cyanobacterial based hydrogen production can be realized.

  8. An alternate line erasure and readout (ALER) method for implementing slot-scan imaging technique with a flat-panel detector--initial experiences.

    PubMed

    Liu, Xinming; Shaw, Chris C; Altunbas, Mustafa C; Wang, Tianpeng

    2006-04-01

    This paper describes and demonstrates an electronic collimation method, referred to as the alternate line erasure and readout (ALER) technique, for implementing slot-scan digital radiography technique with an amorphous silicon (a-Si) thin-film transistor (TFT) array based flat-panel detector. An amorphus selenium (a-Se) flat-panel detector was modified to implement the ALER technique for slot-scan imaging. A stepping-motor driven fore-collimator was mounted in front of an X-ray tube to generate a scanning X-ray fan beam. The scanning speed and magnification were adjusted to synchronize the fan beam motion with the image line readout rate. The image lines on the leading and trailing edges of the fan beam were tracked and alternately reset and read out, respectively. The former operation resulted in the erasure of the scatter signals accumulated in the leading edge image line prior to the arrival of the fan beam. The latter operation resulted in the acquisition of fan beam exposure data integrated in the trailing edge image line right after the fan beam passed. To demonstrate the scatter rejection capability of this technique, an anthropomorphic chest phantom was placed in PA position and scanned at a speed of 576 lines (8.0 cm)/s at 117 kVp and 32 mA. A tungsten bar is placed at the entrance side of the chest phantom to measure the scatter-to-primary ratio (SPR), scatter reduction factor (SRF), and contrast-to-noise ratio degradation factor (CNRDF) in the slot-scan images to evaluate the effectiveness of scatter rejection and the resultant improvement of image quality. SPR and CNRDF in the open-field images were also measured and used as the reference for comparison. A scatter reduction by 86.4 to 95.4% across lower lung and heart regions has been observed with slot-scan imaging. The CNRs have been found to be improved by a factor of 2 in the mediastinum areas over the open-field image as well.

  9. SU-C-16A-01: In Vivo Source Position Verification in High Dose Rate (HDR) Prostate Brachytherapy Using a Flat Panel Imager: Initial Clinical Experience

    SciTech Connect

    Franich, R; Smith, R; Millar, J; Haworth, A; Taylor, M; McDermott, L

    2014-06-15

    Purpose: We report our initial clinical experience with a novel position-sensitive source-tracking system based on a flat panel imager. The system has been trialled with 4 prostate HDR brachytherapy patients (8 treatment fractions) in this initial study. Methods: The flat panel imaging system was mounted under a customised carbon fibre couch top assembly (Figure 1). Three gold fiducial markers were implanted into the prostate of each patient at the time of catheter placement. X-ray dwell position markers were inserted into three catheters and a radiograph acquired to locate the implant relative to the imaging device. During treatment, as the HDR source dwells were delivered, images were acquired and processed to determine the position of the source in the patient. Source positions measured by the imaging device were compared to the treatment plan for verification of treatment delivery. Results: Measured dwell positions provided verification of relative dwell spacing within and between catheters, in the coronal plane. Measurements were typically within 2.0mm (0.2mm – 3.3mm, s.d. 0.8mm) of the planned positions over 60 dwells (Figure 2). Discrimination between larger dwell intervals and catheter differentiation were clear. This confirms important delivery attributes such as correct transfer tube connection, source step size, relative catheter positions and therefore overall correct plan selection and delivery. The fiducial markers, visible on the radiograph, provided verification of treatment delivery to the correct anatomical location. The absolute position of the dwells was determined by comparing the measured dwell positions with the x-ray markers from the radiograph, validating the programmed treatment indexer length. The total impact on procedure time was less than 5 minutes. Conclusion: The novel, noninvasive HDR brachytherapy treatment verification system was used clinically with minor impact on workflow. The system allows verification of correct treatment

  10. SU-E-I-07: Response Characteristics and Signal Conversion Modeling of KV Flat-Panel Detector in Cone Beam CT System

    SciTech Connect

    Wang, Yu; Cao, Ruifen; Pei, Xi; Wang, Hui; Hu, Liqin

    2015-06-15

    Purpose: The flat-panel detector response characteristics are investigated to optimize the scanning parameter considering the image quality and less radiation dose. The signal conversion model is also established to predict the tumor shape and physical thickness changes. Methods: With the ELEKTA XVI system, the planar images of 10cm water phantom were obtained under different image acquisition conditions, including tube voltage, electric current, exposure time and frames. The averaged responses of square area in center were analyzed using Origin8.0. The response characteristics for each scanning parameter were depicted by different fitting types. The transmission measured for 10cm water was compared to Monte Carlo simulation. Using the quadratic calibration method, a series of variable-thickness water phantoms images were acquired to derive the signal conversion model. A 20cm wedge water phantom with 2cm step thickness was used to verify the model. At last, the stability and reproducibility of the model were explored during a four week period. Results: The gray values of image center all decreased with the increase of different image acquisition parameter presets. The fitting types adopted were linear fitting, quadratic polynomial fitting, Gauss fitting and logarithmic fitting with the fitting R-Square 0.992, 0.995, 0.997 and 0.996 respectively. For 10cm water phantom, the transmission measured showed better uniformity than Monte Carlo simulation. The wedge phantom experiment show that the radiological thickness changes prediction error was in the range of (-4mm, 5mm). The signal conversion model remained consistent over a period of four weeks. Conclusion: The flat-panel response decrease with the increase of different scanning parameters. The preferred scanning parameter combination was 100kV, 10mA, 10ms, 15frames. It is suggested that the signal conversion model could effectively be used for tumor shape change and radiological thickness prediction. Supported by

  11. Uterine artery embolization for leiomyomata: optimization of the radiation dose to the patient using a flat-panel detector angiographic suite.

    PubMed

    Sapoval, Marc; Pellerin, Olivier; Rehel, Jean-Luc; Houdoux, Nicolas; Rahmoune, Ghizlaine; Aubert, Bernard; Fitton, Isabelle

    2010-10-01

    The purpose of this study was to assess the ability of low-dose/low-frame fluoroscopy/angiography with a flat-panel detector angiographic suite to reduce the dose delivered to patients during uterine fibroid embolization (UFE). A two-step prospective dosimetric study was conducted, with a flat-panel detector angiography suite (Siemens Axiom Artis) integrating automatic exposure control (AEC), during 20 consecutive UFEs. Patient dosimetry was performed using calibrated thermoluminescent dosimeters placed on the lower posterior pelvis skin. The first step (10 patients; group A) consisted in UFE (bilateral embolization, calibrated microspheres) performed using the following parameters: standard fluoroscopy (15 pulses/s) and angiography (3 frames/s). The second step (next consecutive 10 patients; group B) used low-dose/low-frame fluoroscopy (7.5 pulses/s for catheterization and 3 pulses/s for embolization) and angiography (1 frame/s). We also recorded the total dose-area product (DAP) delivered to the patient and the fluoroscopy time as reported by the manufacturer's dosimetry report. The mean peak skin dose decreased from 2.4 +/- 1.3 to 0.4 +/- 0.3 Gy (P = 0.001) for groups A and B, respectively. The DAP values decreased from 43,113 +/- 27,207 microGy m(2) for group A to 9,515 +/- 4,520 microGy m(2) for group B (P = 0.003). The dose to ovaries and uterus decreased from 378 +/- 238 mGy (group A) to 83 +/- 41 mGy (group B) and from 388 +/- 246 mGy (group A) to 85 +/- 39 mGy (group B), respectively. Effective doses decreased from 112 +/- 71 mSv (group A) to 24 +/- 12 mSv (group B) (P = 0.003). In conclusion, the use of low-dose/low-frame fluoroscopy/angiography, based on a good understanding of the AEC system and also on the technique during uterine fibroid embolization, allows a significant decrease in the dose exposure to the patient.

  12. Uterine Artery Embolization for Leiomyomata: Optimization of the Radiation Dose to the Patient Using a Flat-Panel Detector Angiographic Suite

    SciTech Connect

    Sapoval, Marc Pellerin, Olivier; Rehel, Jean-Luc; Houdoux, Nicolas; Rahmoune, Ghizlaine; Aubert, Bernard; Fitton, Isabelle

    2010-10-15

    The purpose of this study was to assess the ability of low-dose/low-frame fluoroscopy/angiography with a flat-panel detector angiographic suite to reduce the dose delivered to patients during uterine fibroid embolization (UFE). A two-step prospective dosimetric study was conducted, with a flat-panel detector angiography suite (Siemens Axiom Artis) integrating automatic exposure control (AEC), during 20 consecutive UFEs. Patient dosimetry was performed using calibrated thermoluminescent dosimeters placed on the lower posterior pelvis skin. The first step (10 patients; group A) consisted in UFE (bilateral embolization, calibrated microspheres) performed using the following parameters: standard fluoroscopy (15 pulses/s) and angiography (3 frames/s). The second step (next consecutive 10 patients; group B) used low-dose/low-frame fluoroscopy (7.5 pulses/s for catheterization and 3 pulses/s for embolization) and angiography (1 frame/s). We also recorded the total dose-area product (DAP) delivered to the patient and the fluoroscopy time as reported by the manufacturer's dosimetry report. The mean peak skin dose decreased from 2.4 {+-} 1.3 to 0.4 {+-} 0.3 Gy (P = 0.001) for groups A and B, respectively. The DAP values decreased from 43,113 {+-} 27,207 {mu}Gy m{sup 2} for group A to 9,515 {+-} 4,520 {mu}Gy m{sup 2} for group B (P = 0.003). The dose to ovaries and uterus decreased from 378 {+-} 238 mGy (group A) to 83 {+-} 41 mGy (group B) and from 388 {+-} 246 mGy (group A) to 85 {+-} 39 mGy (group B), respectively. Effective doses decreased from 112 {+-} 71 mSv (group A) to 24 {+-} 12 mSv (group B) (P = 0.003). In conclusion, the use of low-dose/low-frame fluoroscopy/angiography, based on a good understanding of the AEC system and also on the technique during uterine fibroid embolization, allows a significant decrease in the dose exposure to the patient.

  13. National Center for Advanced Information Components Manufacturing. Program summary report, Volume 1

    SciTech Connect

    1996-10-01

    The National Center for Advanced Information Components Manufacturing focused on manufacturing research and development for flat panel displays, advanced lithography, microelectronics, and optoelectronics. This report provides an overview of the program, summaries of the technical projects, and key program accomplishments.

  14. Quantitative kinetic analysis of lung nodules using the temporal subtraction technique in dynamic chest radiographies performed with a flat panel detector.

    PubMed

    Tsuchiya, Yuichiro; Kodera, Yoshie; Tanaka, Rie; Sanada, Shigeru

    2009-04-01

    Early detection and treatment of lung cancer is one of the most effective means of reducing cancer mortality, and to this end, chest X-ray radiography has been widely used as a screening method. A related technique based on the development of computer analysis and a flat panel detector (FPD) has enabled the functional evaluation of respiratory kinetics in the chest and is expected to be introduced into clinical practice in the near future. In this study, we developed a computer analysis algorithm to detect lung nodules and to evaluate quantitative kinetics. Breathing chest radiographs obtained by modified FPD and breath synchronization utilizing diaphragmatic analysis of vector movement were converted into four static images by sequential temporal subtraction processing, morphological enhancement processing, kinetic visualization processing, and lung region detection processing. An artificial neural network analyzed these density patterns to detect the true nodules and draw their kinetic tracks. Both the algorithm performance and the evaluation of clinical effectiveness of seven normal patients and simulated nodules showed sufficient detecting capability and kinetic imaging function without significant differences. Our technique can quantitatively evaluate the kinetic range of nodules and is effective in detecting a nodule on a breathing chest radiograph. Moreover, the application of this technique is expected to extend computer-aided diagnosis systems and facilitate the development of an automatic planning system for radiation therapy.

  15. Does Preinterventional Flat-Panel Computer Tomography Pooled Blood Volume Mapping Predict Final Infarct Volume After Mechanical Thrombectomy in Acute Cerebral Artery Occlusion?

    SciTech Connect

    Wagner, Marlies; Kyriakou, Yiannis; Mesnil de Rochemont, Richard du; Singer, Oliver C.; Berkefeld, Joachim

    2013-08-01

    PurposeDecreased cerebral blood volume is known to be a predictor for final infarct volume in acute cerebral artery occlusion. To evaluate the predictability of final infarct volume in patients with acute occlusion of the middle cerebral artery (MCA) or the distal internal carotid artery (ICA) and successful endovascular recanalization, pooled blood volume (PBV) was measured using flat-panel detector computed tomography (FPD CT).Materials and MethodsTwenty patients with acute unilateral occlusion of the MCA or distal ACI without demarcated infarction, as proven by CT at admission, and successful Thrombolysis in cerebral infarction score (TICI 2b or 3) endovascular thrombectomy were included. Cerebral PBV maps were acquired from each patient immediately before endovascular thrombectomy. Twenty-four hours after recanalization, each patient underwent multislice CT to visualize final infarct volume. Extent of the areas of decreased PBV was compared with the final infarct volume proven by follow-up CT the next day.ResultsIn 15 of 20 patients, areas of distinct PBV decrease corresponded to final infarct volume. In 5 patients, areas of decreased PBV overestimated final extension of ischemia probably due to inappropriate timing of data acquisition and misery perfusion.ConclusionPBV mapping using FPD CT is a promising tool to predict areas of irrecoverable brain parenchyma in acute thromboembolic stroke. Further validation is necessary before routine use for decision making for interventional thrombectomy.

  16. A Ring Artifact Correction Method: Validation by Micro-CT Imaging with Flat-Panel Detectors and a 2D Photon-Counting Detector

    PubMed Central

    Eldib, Mohamed Elsayed; Hegazy, Mohamed; Mun, Yang Ji; Cho, Myung Hye; Cho, Min Hyoung; Lee, Soo Yeol

    2017-01-01

    We introduce an efficient ring artifact correction method for a cone-beam computed tomography (CT). In the first step, we correct the defective pixels whose values are close to zero or saturated in the projection domain. In the second step, we compute the mean value at each detector element along the view angle in the sinogram to obtain the one-dimensional (1D) mean vector, and we then compute the 1D correction vector by taking inverse of the mean vector. We multiply the correction vector with the sinogram row by row over all view angles. In the third step, we apply a Gaussian filter on the difference image between the original CT image and the corrected CT image obtained in the previous step. The filtered difference image is added to the corrected CT image to compensate the possible contrast anomaly that may appear due to the contrast change in the sinogram after removing stripe artifacts. We applied the proposed method to the projection data acquired by two flat-panel detectors (FPDs) and a silicon-based photon-counting X-ray detector (PCXD). Micro-CT imaging experiments of phantoms and a small animal have shown that the proposed method can greatly reduce ring artifacts regardless of detector types. Despite the great reduction of ring artifacts, the proposed method does not compromise the original spatial resolution and contrast. PMID:28146088

  17. Development of active matrix flat panel imagers incorporating thin layers of polycrystalline HgI(2) for mammographic x-ray imaging.

    PubMed

    Jiang, Hao; Zhao, Qihua; Antonuk, Larry E; El-Mohri, Youcef; Gupta, Tapan

    2013-02-07

    Active matrix flat-panel imagers (AMFPIs) offer many advantages and have become ubiquitous across a wide variety of medical x-ray imaging applications. However, for mammography, the imaging performance of conventional AMFPIs incorporating CsI:Tl scintillators or a-Se photoconductors is limited by their relatively modest signal-to-noise ratio (SNR), particularly at low x-ray exposures or high spatial resolution. One strategy for overcoming this limitation involves the use of a high gain photoconductor such as mercuric iodide (HgI(2)) which has the potential to improve the SNR by virtue of its low effective work function (W(EFF)). In this study, the performance of direct-detection AMFPI prototypes employing relatively thin layers of polycrystalline HgI(2) operated under mammographic irradiation conditions over a range of 0.5 to 16.0 mR is presented. High x-ray sensitivity (corresponding to W(EFF) values of ∼19 eV), low dark current (<0.1 pA mm(-2)) and good spatial resolution, largely limited by the size of the pixel pitch, were observed. For one prototype, a detective quantum efficiency of ∼70% was observed at an x-ray exposure of ∼0.5 mR at 26 kVp.

  18. Modeling Shift-Variant X-Ray Focal Spot Blur for High-Resolution Flat-Panel Cone-Beam CT

    PubMed Central

    Tilley, Steven; Zbijewski, Wojciech; Siewerdsen, Jeffrey H.; Stayman, J. Webster

    2016-01-01

    Flat-panel cone-beam CT (CBCT) has been applied clinically in a number of high-resolution applications. Increasing geometric magnification can potentially improve resolution, but also increases blur due to an extended x-ray focal-spot. We present a shift-variant focal-spot blur model and incorporate it into a model-based iterative-reconstruction algorithm. We apply this algorithm to simulation and CBCT test-bench data. In a trabecular bone simulation study, we find traditional reconstruction approaches without a blur model exhibit shift-variant resolution properties that depend greatly on the acquisition protocol (e.g. short vs. full scans) and the anode angles of the rays used to reconstruct a particular region. For physical CBCT experiments focal spot blur was characterized and a spatial resolution phantom was scanned and reconstructed. In both experiments image quality using the shift-variant model was significantly improved over approaches that modeled no blur or only a shift-invariant blur, suggesting a potential means to overcome traditional CBCT spatial resolution and system design limitations. PMID:28361129

  19. Performance comparison of an active matrix flat panel imager, computed radiography system, and a screen-film system at four standard radiation qualities.

    PubMed

    Monnin, P; Gutierrez, D; Bulling, S; Lepori, D; Valley, J F; Verdun, F R

    2005-02-01

    Four standard radiation qualities (from RQA 3 to RQA 9) were used to compare the imaging performance of a computed radiography (CR) system (general purpose and high resolution phosphor plates of a Kodak CR 9000 system), a selenium-based direct flat panel detector (Kodak Direct View DR 9000), and a conventional screen-film system (Kodak T-MAT L/RA film with a 3M Trimax Regular screen of speed 400) in conventional radiography. Reference exposure levels were chosen according to the manufacturer's recommendations to be representative of clinical practice (exposure index of 1700 for digital systems and a film optical density of 1.4). With the exception of the RQA 3 beam quality, the exposure levels needed to produce a mean digital signal of 1700 were higher than those needed to obtain a mean film optical density of 1.4. In spite of intense developments in the field of digital detectors, screen-film systems are still very efficient detectors for most of the beam qualities used in radiology. An important outcome of this study is the behavior of the detective quantum efficiency of the digital radiography (DR) system as a function of beam energy. The practice of users to increase beam energy when switching from a screen-film system to a CR system, in order to improve the compromise between patient dose and image quality, might not be appropriate when switching from screen-film to selenium-based DR systems.

  20. Effect of gradual transition of substrate on performance of flat-panel air-cathode microbial fuel cells to treat domestic wastewater.

    PubMed

    Park, Younghyun; Park, Seonghwan; Nguyen, Van Khanh; Kim, Jung Rae; Kim, Hong Suck; Kim, Byung Goon; Yu, Jaecheul; Lee, Taeho

    2017-02-01

    In order to confirm the effects of the low conductivity and biodegradability of wastewater, flat-panel air-cathode microbial fuel cells (FA-MFCs) were operated by supplying substrates with different volume ratios of domestic wastewater mixed with an artificial medium: the artificial medium only, 25% wastewater, 50% wastewater, 75% wastewater, 100% of wastewater with 500mg-COD/L by adding acetate, and raw domestic wastewater (230mg-COD/L). With the increase of wastewater ratio, the maximum power density and organic removal efficiency decreased from 187 to 60W/m(3) and 51.5 to 37.4%, respectively, but the Coulombic efficiency was maintained in the range of 18.0-18.9%. The FA-MFCs could maintain their low internal resistances and overcome the decreasing conductivity. The acetate concentration was more important than the total organics for power production. This study suggests that the FA-MFC configuration has great applicability for practical applications when supplied by domestic wastewater with low conductivity and biodegradability.

  1. Development of pulmonary blood flow evaluation method with a dynamic flat-panel detector: quantitative correlation analysis with findings on perfusion scan.

    PubMed

    Tanaka, Rie; Sanada, Shigeru; Fujimura, Masaki; Yasui, Masahide; Hayashi, Norio; Tsuji, Shiro; Okamoto, Hiroyuki; Nanbu, Yuko; Matsui, Osamu

    2010-01-01

    Pulmonary blood flow is reflected in dynamic chest radiographs as changes in X-ray translucency, i.e., pixel values. Thus, decreased blood flow should be observed as a reduction of the variation of X-ray translucency. We performed the present study to investigate the feasibility of pulmonary blood flow evaluation with a dynamic flat-panel detector (FPD). Sequential chest radiographs of 14 subjects were obtained with a dynamic FPD system. The changes in pixel value in each local area were measured and mapped on the original image by use of a gray scale in which small and large changes were shown in white and black, respectively. The resulting images were compared to the findings in perfusion scans. The cross-correlation coefficients of the changes in pixel value and radioactivity counts in each local area were also computed. In all patients, pulmonary blood flow disorder was indicated as a reduction of changes in pixel values on the mapping image, and a correlation was observed between the distribution of changes in pixel value and those in radioactivity counts (0.7

  2. A Ring Artifact Correction Method: Validation by Micro-CT Imaging with Flat-Panel Detectors and a 2D Photon-Counting Detector.

    PubMed

    Eldib, Mohamed Elsayed; Hegazy, Mohamed; Mun, Yang Ji; Cho, Myung Hye; Cho, Min Hyoung; Lee, Soo Yeol

    2017-01-30

    We introduce an efficient ring artifact correction method for a cone-beam computed tomography (CT). In the first step, we correct the defective pixels whose values are close to zero or saturated in the projection domain. In the second step, we compute the mean value at each detector element along the view angle in the sinogram to obtain the one-dimensional (1D) mean vector, and we then compute the 1D correction vector by taking inverse of the mean vector. We multiply the correction vector with the sinogram row by row over all view angles. In the third step, we apply a Gaussian filter on the difference image between the original CT image and the corrected CT image obtained in the previous step. The filtered difference image is added to the corrected CT image to compensate the possible contrast anomaly that may appear due to the contrast change in the sinogram after removing stripe artifacts. We applied the proposed method to the projection data acquired by two flat-panel detectors (FPDs) and a silicon-based photon-counting X-ray detector (PCXD). Micro-CT imaging experiments of phantoms and a small animal have shown that the proposed method can greatly reduce ring artifacts regardless of detector types. Despite the great reduction of ring artifacts, the proposed method does not compromise the original spatial resolution and contrast.

  3. Cascaded systems analysis of the 3D noise transfer characteristics of flat-panel cone-beam CT.

    PubMed

    Tward, Daniel J; Siewerdsen, Jeffrey H

    2008-12-01

    The physical factors that govern 2D and 3D imaging performance may be understood from quantitative analysis of the spatial-frequency-dependent signal and noise transfer characteristics [e.g., modulation transfer function (MTF), noise-power spectrum (NPS), detective quantum efficiency (DQE), and noise-equivalent quanta (NEQ)] along with a task-based assessment of performance (e.g., detectability index). This paper advances a theoretical framework based on cascaded systems analysis for calculation of such metrics in cone-beam CT (CBCT). The model considers the 2D projection NPS propagated through a series of reconstruction stages to yield the 3D NPS and allows quantitative investigation of tradeoffs in image quality associated with acquisition and reconstruction techniques. While the mathematical process of 3D image reconstruction is deterministic, it is shown that the process is irreversible, the associated reconstruction parameters significantly affect the 3D DQE and NEQ, and system optimization should consider the full 3D imaging chain. Factors considered in the cascade include: system geometry; number of projection views; logarithmic scaling; ramp, apodization, and interpolation filters; 3D back-projection; and 3D sampling (noise aliasing). The model is validated in comparison to experiment across a broad range of dose, reconstruction filters, and voxel sizes, and the effects of 3D noise correlation on detectability are explored. The work presents a model for the 3D NPS, DQE, and NEQ of CBCT that reduces to conventional descriptions of axial CT as a special case and provides a fairly general framework that can be applied to the design and optimization of CBCT systems for various applications.

  4. Cone beam volume CT image artifacts caused by defective cells in x-ray flat panel imagers and the artifact removal using a wavelet-analysis-based algorithm.

    PubMed

    Tang, X; Ning, R; Yu, R; Conover, D

    2001-05-01

    The application of x-ray flat panel imagers (FPIs) in cone beam volume CT (CBVCT) has attracted increasing attention. However, due to a deficient semiconductor array manufacturing process, defective cells unavoidably exist in x-ray FPIs. These defective cells cause their corresponding image pixels in a projection image to behave abnormally in signal gray level, and result in severe streak and ring artifacts in a CBVCT image reconstructed from the projection images. Since a three-dimensional (3-D) back-projection is involved in CBVCT, the formation of the streak and ring artifacts is different from that in the two-dimensional (2-D) fan beam CT. In this paper, a geometric analysis of the abnormality propagation in the 3D back-projection is presented, and the morphology of the streak and ring artifacts caused by the abnormality propagation is investigated through both computer simulation and phantom studies. In order to calibrate those artifacts, a 2D wavelet-analysis-based statistical approach to correct the abnormal pixels is proposed. The approach consists of three steps: (1) the location-invariant defective cells in an x-ray FPI are recognized by applying 2-D wavelet analysis on flat-field images, and a comprehensive defective cell template is acquired; (2) based upon the template, the abnormal signal gray level of the projection image pixels corresponding to the location-invariant defective cells is replaced with the interpolation of that of their normal neighbor pixels; (3) that corresponding to the isolated location-variant defective cells are corrected using a narrow-windowed median filter. The CBVCT images of a CT low-contrast phantom are employed to evaluate this proposed approach, showing that the streak and ring artifacts can be reliably eliminated. The novelty and merit of the approach are the incorporation of the wavelet analysis whose intrinsic multi-resolution analysis and localizability make the recognition algorithm robust under variable x

  5. Advancing Symptom Science Through Symptom Cluster Research: Expert Panel Proceedings and Recommendations.

    PubMed

    Miaskowski, Christine; Barsevick, Andrea; Berger, Ann; Casagrande, Rocco; Grady, Patricia A; Jacobsen, Paul; Kutner, Jean; Patrick, Donald; Zimmerman, Lani; Xiao, Canhua; Matocha, Martha; Marden, Sue

    2017-04-01

    An overview of proceedings, findings, and recommendations from the workshop on "Advancing Symptom Science Through Symptom Cluster Research" sponsored by the National Institute of Nursing Research (NINR) and the Office of Rare Diseases Research, National Center for Advancing Translational Sciences, is presented. This workshop engaged an expert panel in an evidenced-based discussion regarding the state of the science of symptom clusters in chronic conditions including cancer and other rare diseases. An interdisciplinary working group from the extramural research community representing nursing, medicine, oncology, psychology, and bioinformatics was convened at the National Institutes of Health. Based on expertise, members were divided into teams to address key areas: defining characteristics of symptom clusters, priority symptom clusters and underlying mechanisms, measurement issues, targeted interventions, and new analytic strategies. For each area, the evidence was synthesized, limitations and gaps identified, and recommendations for future research delineated. The majority of findings in each area were from studies of oncology patients. However, increasing evidence suggests that symptom clusters occur in patients with other chronic conditions (eg, pulmonary, cardiac, and end-stage renal disease). Nonetheless, symptom cluster research is extremely limited and scientists are just beginning to understand how to investigate symptom clusters by developing frameworks and new methods and approaches. With a focus on personalized care, an understanding of individual susceptibility to symptoms and whether a "driving" symptom exists that triggers other symptoms in the cluster is needed. Also, research aimed at identifying the mechanisms that underlie symptom clusters is essential to developing targeted interventions.

  6. Clinical evaluation of digital radiography based on a large-area cesium iodide-amorphous silicon flat-panel detector compared with screen-film radiography for skeletal system and abdomen.

    PubMed

    Okamura, Terue; Tanaka, Saori; Koyama, Koichi; Norihumi, Nishida; Daikokuya, Hideo; Matsuoka, Toshiyuki; Kishimoto, Kenji; Hatagawa, Masakatsu; Kudoh, Hiroaki; Yamada, Ryusaku

    2002-07-01

    The aim of this clinical study was to compare the image quality of digital radiography using the new digital Bucky system based on a flat-panel detector with that of a conventional screen-film system for the skeletal structure and the abdomen. Fifty patients were examined using digital radiography with a flat-panel detector and screen-film systems, 25 for the skeletal structures and 25 for the abdomen. Six radiologists judged each paired image acquired under the same exposure parameters concerning three observation items for the bone and six items for the abdomen. Digital radiographic images for the bone were evaluated to be similar to screen-film images at the mean of 42.2%, to be superior at 50.2%, and to be inferior at 7.6%. Digital radiographic images for the abdomen were judged to be similar to screen-film images at the mean of 43.4%, superior at 52.4%, and inferior at 4.2%; thus, digital radiographic images were estimated to be either similar as or superior to screen-film images at over 92% for the bone and abdomen. On the statistical analysis, digital radiographic images were also judged to be preferred significantly in the most items for the bone and abdomen. In conclusion, the image quality of digital radiography with a flat-panel detector was superior to that of a screen-film system under the same exposure parameters, suggesting that dose reduction is possible with digital radiography.

  7. Optimization of key building blocks for a large-area radiographic and fluoroscopic dynamic digital x-ray detector based on a-Si:H/CsI:Tl flat panel technology

    NASA Astrophysics Data System (ADS)

    Ducourant, Thierry; Michel, Marc; Vieux, Gerard; Peppler, Tobias; Trochet, J. C.; Schulz, Reiner F.; Bastiaens, Raoul J. M.; Busse, Falko

    2000-04-01

    This paper introduces the key design optimizations which have been carried out recently in Trixell in order to prepare the future family of large area, combined static (Radiography) and dynamic (Fluoroscopy, Cardio...) digital X-ray detectors based on a-Si:H/CsI:Tl flat panel technology. These optimizations have been carried out on a 16' X 12' prototype that has been designed and built in a product-oriented way. We describe the detector technology and give some of its main characteristics, as well as some preliminary measurement results.The heart of the new prototype is a Cesium Iodide scintillating screen, directly evaporated onto a 2 K X 2.5 K pixel, array of amorphous silicon photodiodes and TFTs deposited on a glass substrate. The pixel pitch is 155 micrometer. The detective flat panel is connected to dedicated electronics which provides line addressing, low-noise column readout and multiplexing into a serial electrical signal. This signal is digitized over 14 bits to provide a direct digital image output, available for the host radiology system via an optical fiber. This type of detector (flat panel + electronics) is built into a light and thin (less than 100 mm) packaging which can be easily integrated in various x-ray equipment such as R&F tables, Angiography systems (incl. Cardiology), and mobile C-arm systems.

  8. Strategies to improve the signal and noise performance of active matrix, flat-panel imagers for diagnostic x-ray applications.

    PubMed

    Antonuk, L E; Jee, K W; El-Mohri, Y; Maolinbay, M; Nassif, S; Rong, X; Zhao, Q; Siewerdsen, J H; Street, R A; Shah, K S

    2000-02-01

    A theoretical investigation of factors limiting the detective quantum efficiency (DQE) of active matrix flat-panel imagers (AMFPIs), and of methods to overcome these limitations, is reported. At the higher exposure levels associated with radiography, the present generation of AMFPIs is capable of exhibiting DQE performance equivalent, or superior, to that of existing film-screen and computed radiography systems. However, at exposure levels commonly encountered in fluoroscopy, AMFPIs exhibit significantly reduced DQE and this problem is accentuated at higher spatial frequencies. The problem applies both to AMFPIs that rely on indirect detection as well as direct detection of the incident radiation. This reduced performance derives from the relatively large magnitude of the square of the total additive noise compared to the system gain for existing AMFPIs. In order to circumvent these restrictions, a variety of strategies to decrease additive noise and enhance system gain are proposed. Additive noise could be reduced through improved preamplifier, pixel and array design, including the incorporation of compensation lines to sample external line noise. System gain could be enhanced through the use of continuous photodiodes, pixel amplifiers, or higher gain x-ray converters such as lead iodide. The feasibility of these and other strategies is discussed and potential improvements to DQE performance are quantified through a theoretical investigation of a variety of hypothetical 200 microm pitch designs. At low exposures, such improvements could greatly increase the magnitude of the low spatial frequency component of the DQE, rendering it practically independent of exposure while simultaneously reducing the falloff in DQE at higher spatial frequencies. Furthermore, such noise reduction and gain enhancement could lead to the development of AMFPIs with high DQE performance which are capable of providing both high resolution radiographic images, at approximately 100 microm

  9. A real-time flat-panel X-ray pixel imaging system for low-dose medical diagnostics and craniofacial applications.

    PubMed

    Chapuy, S; Dimcovski, D; Dimcovski, Z; Grigoriev, E; Grob, E; Ligier, Y; Pachoud, M; Riondel, F; Rüfenacht, D; Sayegh, C; Terrier, F; Valley, J F; Verdun, F R

    2000-01-01

    The aim of this study was to evaluate on-line performance of a real-time digital imaging system based on amorphous silicon technology and to compare it with conventional film-screen equipment. The digital detecting imager consists of (1) a converter, which transforms the energy of the incident X rays into light; (2) a real-time digital detecting system, capable of producing as many as 10 pictures per second using a large-area pixel matrix (20 x 20 cm2) based on solid-state amorphous silicon sensor technology with a pitch of 400 microns; and (3) appropriate computer tools for control, real-time image treatment, data representation, and off-line analysis. Different phantoms were used for qualitative comparison with the conventional film-screen technique, with images obtained with both systems at the normal dose (used as a reference), as well as with dose reduction by a factor of 10 to 100. Basic image quality parameters evaluated showed that the response of the detector is linear in a wide range of entrance air kerma; the dynamic range is higher compared with the conventional film-screen combination; the spatial resolution is 1.25 lp per millimeter, as expected from the pixel size; and good image quality is ensured at doses substantially lower than for the film-screen technique. The flat-panel X-ray imager based on amorphous silicon technology implemented in standard radiographic equipment permits acquisition of real-time images in radiology (as many as 10 images per second) of diagnostic quality with a marked reduction of dose (as much as 100 times) and better contrast compared with the standard film technique. Preliminary results obtained with a 100-micron pitch imager based on the same technology show better quality but a less substantial dose reduction. Applications in craniofacial surgery look promising.

  10. High-EPA Biomass from Nannochloropsis salina Cultivated in a Flat-Panel Photo-Bioreactor on a Process Water-Enriched Growth Medium

    PubMed Central

    Safafar, Hamed; Hass, Michael Z.; Møller, Per; Holdt, Susan L.; Jacobsen, Charlotte

    2016-01-01

    Nannochloropsis salina was grown on a mixture of standard growth media and pre-gasified industrial process water representing effluent from a local biogas plant. The study aimed to investigate the effects of enriched growth media and cultivation time on nutritional composition of Nannochloropsis salina biomass, with a focus on eicosapentaenoic acid (EPA). Variations in fatty acid composition, lipids, protein, amino acids, tocopherols and pigments were studied and results compared to algae cultivated on F/2 media as reference. Mixed growth media and process water enhanced the nutritional quality of Nannochloropsis salina in laboratory scale when compared to algae cultivated in standard F/2 medium. Data from laboratory scale translated to the large scale using a 4000 L flat panel photo-bioreactor system. The algae growth rate in winter conditions in Denmark was slow, but results revealed that large-scale cultivation of Nannochloropsis salina at these conditions could improve the nutritional properties such as EPA, tocopherol, protein and carotenoids compared to laboratory-scale cultivated microalgae. EPA reached 44.2% ± 2.30% of total fatty acids, and α-tocopherol reached 431 ± 28 µg/g of biomass dry weight after 21 days of cultivation. Variations in chemical compositions of Nannochloropsis salina were studied during the course of cultivation. Nannochloropsis salina can be presented as a good candidate for winter time cultivation in Denmark. The resulting biomass is a rich source of EPA and also a good source of protein (amino acids), tocopherols and carotenoids for potential use in aquaculture feed industry. PMID:27483291

  11. Noise variance analysis using a flat panel x-ray detector: A method for additive noise assessment with application to breast CT applications

    PubMed Central

    Yang, Kai; Huang, Shih-Ying; Packard, Nathan J.; Boone, John M.

    2010-01-01

    Purpose: A simplified linear model approach was proposed to accurately model the response of a flat panel detector used for breast CT (bCT). Methods: Individual detector pixel mean and variance were measured from bCT projection images acquired both in air and with a polyethylene cylinder, with the detector operating in both fixed low gain and dynamic gain mode. Once the coefficients of the linear model are determined, the fractional additive noise can be used as a quantitative metric to evaluate the system’s efficiency in utilizing x-ray photons, including the performance of different gain modes of the detector. Results: Fractional additive noise increases as the object thickness increases or as the radiation dose to the detector decreases. For bCT scan techniques on the UC Davis prototype scanner (80 kVp, 500 views total, 30 frames∕s), in the low gain mode, additive noise contributes 21% of the total pixel noise variance for a 10 cm object and 44% for a 17 cm object. With the dynamic gain mode, additive noise only represents approximately 2.6% of the total pixel noise variance for a 10 cm object and 7.3% for a 17 cm object. Conclusions: The existence of the signal-independent additive noise is the primary cause for a quadratic relationship between bCT noise variance and the inverse of radiation dose at the detector. With the knowledge of the additive noise contribution to experimentally acquired images, system modifications can be made to reduce the impact of additive noise and improve the quantum noise efficiency of the bCT system. PMID:20831059

  12. Noise variance analysis using a flat panel x-ray detector: A method for additive noise assessment with application to breast CT applications

    SciTech Connect

    Yang Kai; Huang, Shih-Ying; Packard, Nathan J.; Boone, John M.

    2010-07-15

    Purpose: A simplified linear model approach was proposed to accurately model the response of a flat panel detector used for breast CT (bCT). Methods: Individual detector pixel mean and variance were measured from bCT projection images acquired both in air and with a polyethylene cylinder, with the detector operating in both fixed low gain and dynamic gain mode. Once the coefficients of the linear model are determined, the fractional additive noise can be used as a quantitative metric to evaluate the system's efficiency in utilizing x-ray photons, including the performance of different gain modes of the detector. Results: Fractional additive noise increases as the object thickness increases or as the radiation dose to the detector decreases. For bCT scan techniques on the UC Davis prototype scanner (80 kVp, 500 views total, 30 frames/s), in the low gain mode, additive noise contributes 21% of the total pixel noise variance for a 10 cm object and 44% for a 17 cm object. With the dynamic gain mode, additive noise only represents approximately 2.6% of the total pixel noise variance for a 10 cm object and 7.3% for a 17 cm object. Conclusions: The existence of the signal-independent additive noise is the primary cause for a quadratic relationship between bCT noise variance and the inverse of radiation dose at the detector. With the knowledge of the additive noise contribution to experimentally acquired images, system modifications can be made to reduce the impact of additive noise and improve the quantum noise efficiency of the bCT system.

  13. High-EPA Biomass from Nannochloropsis salina Cultivated in a Flat-Panel Photo-Bioreactor on a Process Water-Enriched Growth Medium.

    PubMed

    Safafar, Hamed; Hass, Michael Z; Møller, Per; Holdt, Susan L; Jacobsen, Charlotte

    2016-07-29

    Nannochloropsis salina was grown on a mixture of standard growth media and pre-gasified industrial process water representing effluent from a local biogas plant. The study aimed to investigate the effects of enriched growth media and cultivation time on nutritional composition of Nannochloropsis salina biomass, with a focus on eicosapentaenoic acid (EPA). Variations in fatty acid composition, lipids, protein, amino acids, tocopherols and pigments were studied and results compared to algae cultivated on F/2 media as reference. Mixed growth media and process water enhanced the nutritional quality of Nannochloropsis salina in laboratory scale when compared to algae cultivated in standard F/2 medium. Data from laboratory scale translated to the large scale using a 4000 L flat panel photo-bioreactor system. The algae growth rate in winter conditions in Denmark was slow, but results revealed that large-scale cultivation of Nannochloropsis salina at these conditions could improve the nutritional properties such as EPA, tocopherol, protein and carotenoids compared to laboratory-scale cultivated microalgae. EPA reached 44.2% ± 2.30% of total fatty acids, and α-tocopherol reached 431 ± 28 µg/g of biomass dry weight after 21 days of cultivation. Variations in chemical compositions of Nannochloropsis salina were studied during the course of cultivation. Nannochloropsis salina can be presented as a good candidate for winter time cultivation in Denmark. The resulting biomass is a rich source of EPA and also a good source of protein (amino acids), tocopherols and carotenoids for potential use in aquaculture feed industry.

  14. Imaging responses of on-site CsI and Gd2O2S flat-panel detectors: Dependence on the tube voltage

    NASA Astrophysics Data System (ADS)

    Jeon, Hosang; Chung, Myung Jin; Youn, Seungman; Nam, Jiho; Lee, Jayoung; Park, Dahl; Kim, Wontaek; Ki, Yongkan; Kim, Ho Kyung

    2015-07-01

    One of the emerging issues in radiography is low-dose imaging to minimize patient's exposure. The scintillating materials employed in most indirect flat-panel detectors show a drastic change of X-ray photon absorption efficiency around their K-edge energies that consequently affects image quality. Using various tube voltages, we investigated the imaging performance of most popular scintillators: cesium iodide (CsI) and gadolinium oxysulfide (Gd2O2S). The integrated detective quantum efficiencies (iDQE) of four detectors installed in the same hospital were evaluated according to the standardized procedure IEC 62220-1 at tube voltages of 40 - 120 kVp. The iDQE values of the Gd2O2S detectors were normalized by those of CsI detectors to exclude the effects of image postprocessing. The contrast-to-noise ratios (CNR) were also evaluated by using an anthropomorphic chest phantom. The iDQE of the CsI detector outperformed that of the Gd2O2S detector over all tube voltages. Moreover, we noted that the iDQE of the Gd2O2S detectors quickly rolled off with decreasing tube voltage under 70 kVp. The CNRs of the two scintillators were similar at 120 kVp. At 60 kVp, however, the CNR of Gd2O2S was about half that of CsI. Compared to the Gd2O2S detectors, variations in the DQE performance of the CsI detectors were relatively immune to variations in the applied tube voltages. Therefore, we claim that Gd2O2S detectors are inappropriate for use in low-tube-voltage imaging (e.g., extremities and pediatrics) with low patient exposure.

  15. Quantitative comparison using generalized relative object detectability (G-ROD) metrics of an amorphous selenium detector with high resolution microangiographic fluoroscopes (MAF) and standard flat panel detectors (FPD)

    NASA Astrophysics Data System (ADS)

    Russ, M.; Shankar, A.; Jain, A.; Setlur Nagesh, S. V.; Ionita, C. N.; Scott, C.; Karim, K. S.; Bednarek, D. R.; Rudin, S.

    2016-03-01

    A novel amorphous selenium (a-Se) direct detector with CMOS readout has been designed, and relative detector performance investigated. The detector features include a 25μm pixel pitch, and 1000μm thick a-Se layer operating at 10V/μm bias field. A simulated detector DQE was determined, and used in comparative calculations of the Relative Object Detectability (ROD) family of prewhitening matched-filter (PWMF) observer and non-pre-whitening matched filter (NPWMF) observer model metrics to gauge a-Se detector performance against existing high resolution micro-angiographic fluoroscopic (MAF) detectors and a standard flat panel detector (FPD). The PWMF-ROD or ROD metric compares two x-ray imaging detectors in their relative abilities in imaging a given object by taking the integral over spatial frequencies of the Fourier transform of the detector DQE weighted by an object function, divided by the comparable integral for a different detector. The generalized-ROD (G-ROD) metric incorporates clinically relevant parameters (focal- spot size, magnification, and scatter) to show the degradation in imaging performance for detectors that are part of an imaging chain. Preliminary ROD calculations using simulated spheres as the object predicted superior imaging performance by the a-Se detector as compared to existing detectors. New PWMF-G-ROD and NPWMF-G-ROD results still indicate better performance by the a-Se detector in an imaging chain over all sphere sizes for various focal spot sizes and magnifications, although a-Se performance advantages were degraded by focal spot blurring. Nevertheless, the a-Se technology has great potential to provide break- through abilities such as visualization of fine details including of neuro-vascular perforator vessels and of small vascular devices.

  16. MTF characterization in 2D and 3D for a high resolution, large field of view flat panel imager for cone beam CT

    NASA Astrophysics Data System (ADS)

    Shah, Jainil; Mann, Steve D.; Tornai, Martin P.; Richmond, Michelle; Zentai, George

    2014-03-01

    The 2D and 3D modulation transfer functions (MTFs) of a custom made, large 40x30cm2 area, 600- micron CsI-TFT based flat panel imager having 127-micron pixellation, along with the micro-fiber scintillator structure, were characterized in detail using various techniques. The larger area detector yields a reconstructed FOV of 25cm diameter with an 80cm SID in CT mode. The MTFs were determined with 1x1 (intrinsic) binning. The 2D MTFs were determined using a 50.8 micron tungsten wire and a solid lead edge, and the 3D MTF was measured using a custom made phantom consisting of three nearly orthogonal 50.8 micron tungsten wires suspended in an acrylic cubic frame. The 2D projection data was reconstructed using an iterative OSC algorithm using 16 subsets and 5 iterations. As additional verification of the resolution, along with scatter, the Catphan® phantom was also imaged and reconstructed with identical parameters. The measured 2D MTF was ~4% using the wire technique and ~1% using the edge technique at the 3.94 lp/mm Nyquist cut-off frequency. The average 3D MTF measured along the wires was ~8% at the Nyquist. At 50% MTF, the resolutions were 1.2 and 2.1 lp/mm in 2D and 3D, respectively. In the Catphan® phantom, the 1.7 lp/mm bars were easily observed. Lastly, the 3D MTF measured on the three wires has an observed 5.9% RMSD, indicating that the resolution of the imaging system is uniform and spatially independent. This high performance detector is integrated into a dedicated breast SPECT-CT imaging system.

  17. Evaluation of detector dynamic range in the x-ray exposure domain in mammography: a comparison between film-screen and flat panel detector systems.

    PubMed

    Cooper, Virgil N; Oshiro, Thomas; Cagnon, Christopher H; Bassett, Lawrence W; McLeod-Stockmann, Tyler M; Bezrukiy, Nikita V

    2003-10-01

    Digital detectors in mammography have wide dynamic range in addition to the benefit of decoupled acquisition and display. How wide the dynamic range is and how it compares to film-screen systems in the clinical x-ray exposure domain are unclear. In this work, we compare the effective dynamic ranges of film-screen and flat panel mammography systems, along with the dynamic ranges of their component image receptors in the clinical x-ray exposure domain. An ACR mammography phantom was imaged using variable mAs (exposure) values for both systems. The dynamic range of the contrast-limited film-screen system was defined as that ratio of mAs (exposure) values for a 26 kVp Mo/Mo (HVL=0.34 mm Al) beam that yielded passing phantom scores. The same approach was done for the noise-limited digital system. Data from three independent observers delineated a useful phantom background optical density range of 1.27 to 2.63, which corresponded to a dynamic range of 2.3 +/- 0.53. The digital system had a dynamic range of 9.9 +/- 1.8, which was wider than the film-screen system (p<0.02). The dynamic range of the film-screen system was limited by the dynamic range of the film. The digital detector, on the other hand, had an estimated dynamic range of 42, which was wider than the dynamic range of the digital system in its entirety by a factor of 4. The generator/tube combination was the limiting factor in determining the digital system's dynamic range.

  18. Sequential dual-energy subtraction technique with a dynamic flat-panel detector (FPD): primary study for image-guided radiation therapy (IGRT).

    PubMed

    Tanaka, Rie; Sanada, Shigeru; Matsui, Takeshi; Hayashi, Norio; Matsui, Osamu

    2008-07-01

    A sequential dual-energy subtraction technique for image-guided radiation therapy (IGRT) was developed. Here, we report on a computerized method for creating sequential soft-tissue images and the accuracy of tracking targets on the images obtained, in comparison to conventional fluoroscopic images. Two sets of sequential chest images during respiration of a normal subject were obtained with X-rays of different energy separately with a flat-panel detector (FPD). Sequential soft-tissue images were created from the two sets of sequential images consisting of real-time images and reference template images, respectively. The creation of sequential soft-tissue images consisted of three steps: one-to-one image correspondence of the two sequential images, image registration, and image subtraction in each frame. Motion tracking of lung vessels was then performed by the template-matching technique. For evaluation of the accuracy of motion tracking on the sequential soft-tissue images, the results were compared with those on the original sequential images. Sequential soft-tissue images provided more accurate tracking than the original images (P < 0.01). There was no significant error throughout all frames in the soft-tissue images, whereas the rib shadow introduced a tracking error in the original images. The maximum errors were 4.1 +/- 0.3 mm in the sequential soft-tissue images and 28.1 +/- 20.0 mm in the original images. In conclusion, sequential soft-tissue images were helpful for tracking of a target affected by respiratory motion. Dual-energy subtraction has the potential to improve the accuracy of IGRT without implanted markers.

  19. The design and imaging characteristics of dynamic, solid-state, flat-panel x-ray image detectors for digital fluoroscopy and fluorography.

    PubMed

    Cowen, A R; Davies, A G; Sivananthan, M U

    2008-10-01

    Dynamic, flat-panel, solid-state, x-ray image detectors for use in digital fluoroscopy and fluorography emerged at the turn of the millennium. This new generation of dynamic detectors utilize a thin layer of x-ray absorptive material superimposed upon an electronic active matrix array fabricated in a film of hydrogenated amorphous silicon (a-Si:H). Dynamic solid-state detectors come in two basic designs, the indirect-conversion (x-ray scintillator based) and the direct-conversion (x-ray photoconductor based). This review explains the underlying principles and enabling technologies associated with these detector designs, and evaluates their physical imaging characteristics, comparing their performance against the long established x-ray image intensifier television (TV) system. Solid-state detectors afford a number of physical imaging benefits compared with the latter. These include zero geometrical distortion and vignetting, immunity from blooming at exposure highlights and negligible contrast loss (due to internal scatter). They also exhibit a wider dynamic range and maintain higher spatial resolution when imaging over larger fields of view. The detective quantum efficiency of indirect-conversion, dynamic, solid-state detectors is superior to that of both x-ray image intensifier TV systems and direct-conversion detectors. Dynamic solid-state detectors are playing a burgeoning role in fluoroscopy-guided diagnosis and intervention, leading to the displacement of x-ray image intensifier TV-based systems. Future trends in dynamic, solid-state, digital fluoroscopy detectors are also briefly considered. These include the growth in associated three-dimensional (3D) visualization techniques and potential improvements in dynamic detector design.

  20. Investigation on effect of image lag in fluoroscopic images obtained with a dynamic flat-panel detector (FPD) on accuracy of target tracking in radiotherapy.

    PubMed

    Tanaka, Rie; Ichikawa, Katsuhiro; Mori, Shinichiro; Dobashi, Suguru; Kumagai, Motoki; Kawashima, Hiroki; Minohara, Shinichi; Sanada, Sigeru

    2010-01-01

    Real-time tumor tracking in external radiotherapy can be achieved by diagnostic (kV) X-ray imaging with a dynamic flat-panel detector (FPD). The purpose of this study was to address image lag in target tracking and its influence on the accuracy of tumor tracking. Fluoroscopic images were obtained using a direct type of dynamic FPD. Image lag properties were measured without test devices according to IEC 62220-1. Modulation transfer function (MTF) and profile curves were measured on the edges of a moving tungsten plate at movement rate of 10 and 20 mm/s, covering lung tumor movement of normal breathing. A lung tumor and metal sphere with blurred edge due to image lag was simulated using the results and then superimposed on breathing chest radiographs of a patient. The moving target with and without image lag was traced using a template-matching technique. In the results, the image lag for the first frame after X-ray cutoff was 2.0% and decreased to less than 0.1% in the fifth frame. In the measurement of profile curves on the edges of static and moving tungsten material plates, the effect of image lag was seen as blurred edges of the plate. The blurred edges of a moving target were indicated as reduction of MTF. However, the target could be traced within an error of ± 5 mm. The results indicated that there was no effect of image lag on target tracking in usual breathing speed in a radiotherapy situation.

  1. Cone-beam CT with a flat-panel detector on a mobile C-arm: preclinical investigation in image-guided surgery of the head and neck

    NASA Astrophysics Data System (ADS)

    Siewerdsen, J. H.; Chan, Y.; Rafferty, M. A.; Moseley, D. J.; Jaffray, D. A.; Irish, J. C.

    2005-04-01

    A promising imaging platform for combined low-dose fluoroscopy and cone-beam CT (CBCT) guidance of interventional procedures has been developed in our laboratory. Based on a mobile isocentric C-arm (Siemens PowerMobil) incorporating a high-performance flat-panel detector (Varian PaxScan 4030CB), the system demonstrates sub-mm 3D spatial resolution and soft-tissue visibility with field of view sufficient for head and body sites. For pre-clinical studies in head neck tumor surgery, we hypothesize that the 3D intraoperative information provided by CBCT permits precise, aggressive techniques with improved avoidance of critical structures. The objectives include: 1) quantify improvement in surgical performance achieved with CBCT guidance compared to open and endoscopic techniques; and 2) investigate specific, challenging surgical tasks under CBCT guidance. Investigations proceed from an idealized phantom model to cadaveric specimens. A novel surgical performance evaluation method based on statistical decision theory is applied to excision and avoidance tasks. Analogous to receiver operating characteristic (ROC) analysis in medical imaging, the method quantifies surgical performance in terms of Lesion-Excised (True-Positve), Lesion-Remaining (False-Negative), Normal-Excised (False-Positive), and Normal-Remaining (True-Negative) fractions. Conservative and aggressive excision and avoidance tasks are executed in 12 cadaveric specimens with and without CBCT guidance, including: dissection through dura, preservation of posterior lamina, ethmoid air cells removal, exposure of peri-orbita, and excision of infiltrated bone in the skull base (clivus). Intraoperative CBCT data was found to dramatically improve surgical performance and confidence in the execution of such tasks. Pre-clinical investigation of this platform in head and neck surgery, as well as spinal, trauma, biopsy, and other nonvascular procedures, is discussed.

  2. Voxel-Based Sensitivity of Flat-Panel CT for the Detection of Intracranial Hemorrhage: Comparison to Multi-Detector CT

    PubMed Central

    Frölich, Andreas M.; Buhk, Jan-Hendrik; Fiehler, Jens; Kemmling, Andre

    2016-01-01

    Objectives Flat-panel CT (FPCT) allows cross-sectional parenchymal, vascular and perfusion imaging within the angiography suite, which could greatly facilitate acute stroke management. We hypothesized that FPCT offers equal diagnostic accuracy compared to multi-detector CT (MDCT) as a primary tool to exclude intracranial hemorrhage. Methods 22 patients with intracranial hematomas who had both MDCT and FPCT performed within 24 hours were retrospectively identified. Patients with visible change in hematoma size or configuration were excluded. Two raters independently segmented hemorrhagic lesions. Data sets and corresponding binary lesion maps were co-registered to compare hematoma volume. Diagnostic accuracy of FPCT to detect hemorrhage was calculated from voxel-wise analysis of lesion overlap compared to reference MDCT. Results Mean hematoma size was similar between MDCT (16.2±8.9 ml) and FPCT (16.1±8.6 ml), with near perfect correlation of hematoma sizes between modalities (ρ = 0.95, p<0.001). Sensitivity and specificity of FPCT to detect hemorrhagic voxels was 61.6% and 99.8% for intraventricular hematomas and 67.7% and 99.5% for all other intracranial hematomas. Conclusions In this small sample containing predominantly cases with subarachnoid hemorrhage, FPCT based assessment of hemorrhagic volume in brain yields acceptable accuracy compared to reference MDCT, albeit with a limited sensitivity on a voxel level. Further assessment and improvement of FPCT is necessary before it can be applied as a primary imaging modality to exclude intracranial hemorrhage in acute stroke patients. PMID:27806106

  3. Integrated radiotherapy imaging system (IRIS): design considerations of tumour tracking with linac gantry-mounted diagnostic x-ray systems with flat-panel detectors.

    PubMed

    Berbeco, Ross I; Jiang, Steve B; Sharp, Gregory C; Chen, George T; Mostafavi, Hassan; Shirato, Hiroki

    2004-01-21

    The design of an integrated radiotherapy imaging system (IRIS), consisting of gantry mounted diagnostic (kV) x-ray tubes and fast read-out flat-panel amorphous-silicon detectors, has been studied. The system is meant to be capable of three main functions: radiographs for three-dimensional (3D) patient set-up, cone-beam CT and real-time tumour/marker tracking. The goal of the current study is to determine whether one source/panel pair is sufficient for real-time tumour/marker tracking and, if two are needed, the optimal position of each relative to other components and the isocentre. A single gantry-mounted source/imager pair is certainly capable of the first two of the three functions listed above and may also be useful for the third, if combined with prior knowledge of the target's trajectory. This would be necessary because only motion in two dimensions is visible with a single imager/source system. However, with previously collected information about the trajectory, the third coordinate may be derived from the other two with sufficient accuracy to facilitate tracking. This deduction of the third coordinate can only be made if the 3D tumour/marker trajectory is consistent from fraction to fraction. The feasibility of tumour tracking with one source/imager pair has been theoretically examined here using measured lung marker trajectory data for seven patients from multiple treatment fractions. The patients' selection criteria include minimum mean amplitudes of the tumour motions greater than 1 cm peak-to-peak. The marker trajectory for each patient was modelled using the first fraction data. Then for the rest of the data, marker positions were derived from the imager projections at various gantry angles and compared with the measured tumour positions. Our results show that, due to the three dimensionality and irregular trajectory characteristics of tumour motion, on a fraction-to-fraction basis, a 'monoscopic' system (single source/imager) is inadequate for

  4. Integrated radiotherapy imaging system (IRIS): design considerations of tumour tracking with linac gantry-mounted diagnostic x-ray systems with flat-panel detectors

    NASA Astrophysics Data System (ADS)

    Berbeco, Ross I.; Jiang, Steve B.; Sharp, Gregory C.; Chen, George T. Y.; Mostafavi, Hassan; Shirato, Hiroki

    2004-01-01

    The design of an integrated radiotherapy imaging system (IRIS), consisting of gantry mounted diagnostic (kV) x-ray tubes and fast read-out flat-panel amorphous-silicon detectors, has been studied. The system is meant to be capable of three main functions: radiographs for three-dimensional (3D) patient set-up, cone-beam CT and real-time tumour/marker tracking. The goal of the current study is to determine whether one source/panel pair is sufficient for real-time tumour/marker tracking and, if two are needed, the optimal position of each relative to other components and the isocentre. A single gantry-mounted source/imager pair is certainly capable of the first two of the three functions listed above and may also be useful for the third, if combined with prior knowledge of the target's trajectory. This would be necessary because only motion in two dimensions is visible with a single imager/source system. However, with previously collected information about the trajectory, the third coordinate may be derived from the other two with sufficient accuracy to facilitate tracking. This deduction of the third coordinate can only be made if the 3D tumour/marker trajectory is consistent from fraction to fraction. The feasibility of tumour tracking with one source/imager pair has been theoretically examined here using measured lung marker trajectory data for seven patients from multiple treatment fractions. The patients' selection criteria include minimum mean amplitudes of the tumour motions greater than 1 cm peak-to-peak. The marker trajectory for each patient was modelled using the first fraction data. Then for the rest of the data, marker positions were derived from the imager projections at various gantry angles and compared with the measured tumour positions. Our results show that, due to the three dimensionality and irregular trajectory characteristics of tumour motion, on a fraction-to-fraction basis, a 'monoscopic' system (single source/imager) is inadequate for

  5. Application of an advanced atmospheric mesoscale model to dispersion in the Rocky Flats, Colorado vicinity

    SciTech Connect

    Poulos, G.S.; Bossert, J.E.

    1993-01-01

    Atmospheric Studies in Complex Terrain (ASCOT) program sponsored a field experiment in the winter of 1991 near Rocky Flats, Colorado. Both meteorological and tracer dispersion measurements were taken. These two data sets provided an opportunity to investigate the influence of terrain-generated, radiatively-driven flows on the dispersion of the tracer. We use the Regional Atmospheric Modeling System (RAMS), originally developed at Colorado State University, to simulate meteorological conditions and tracer dispersion on the case night of 4-5 February 1991. The simulations described herein reveal considerable information about the extent to which the Rocky Mountains influence the flow along the Front Range , the importance of diffusion when simulating drainage flows and the computing needs of simulations in complex terrain regions.

  6. Application of an advanced atmospheric mesoscale model to dispersion in the Rocky Flats, Colorado vicinity

    SciTech Connect

    Poulos, G.S.; Bossert, J.E.

    1993-02-01

    Atmospheric Studies in Complex Terrain (ASCOT) program sponsored a field experiment in the winter of 1991 near Rocky Flats, Colorado. Both meteorological and tracer dispersion measurements were taken. These two data sets provided an opportunity to investigate the influence of terrain-generated, radiatively-driven flows on the dispersion of the tracer. We use the Regional Atmospheric Modeling System (RAMS), originally developed at Colorado State University, to simulate meteorological conditions and tracer dispersion on the case night of 4-5 February 1991. The simulations described herein reveal considerable information about the extent to which the Rocky Mountains influence the flow along the Front Range , the importance of diffusion when simulating drainage flows and the computing needs of simulations in complex terrain regions.

  7. Development and validation of an advanced low-order panel method

    NASA Technical Reports Server (NTRS)

    Ashby, Dale L.; Iguchi, Steven K.; Dudley, Michael

    1988-01-01

    A low-order potential-flow panel code, PMARC, for modeling complex three-dimensional geometries, is currently being developed at NASA Ames Research Center. The PMARC code was derived from a code named VSAERO that was developed for Ames Research Center by Analytical Methods, Inc. In addition to modeling potential flow over three-dimensional geometries, the present version of PMARC includes several advanced features such as an internal flow model, a simple jet wake model, and a time-stepping wake model. Data management within the code was optimized by the use of adjustable size arrays for rapidly changing the size capability of the code, reorganization of the output file and adopting a new plot file format. Preliminary versions of a geometry preprocessor and a geometry/aerodynamic data postprocessor are also available for use with PMARC. Several test cases are discussed to highlight the capabilities of the internal flow model, the jet wake model, and the time-stepping wake model.

  8. Psychophysical evaluation of the image quality of a dynamic flat-panel digital x-ray image detector using the threshold contrast detail detectability (TCDD) technique

    NASA Astrophysics Data System (ADS)

    Davies, Andrew G.; Cowen, Arnold R.; Bruijns, Tom J. C.

    1999-05-01

    We are currently in an era of active development of the digital X-ray imaging detectors that will serve the radiological communities in the new millennium. The rigorous comparative physical evaluations of such devices are therefore becoming increasingly important from both the technical and clinical perspectives. The authors have been actively involved in the evaluation of a clinical demonstration version of a flat-panel dynamic digital X-ray image detector (or FDXD). Results of objective physical evaluation of this device have been presented elsewhere at this conference. The imaging performance of FDXD under radiographic exposure conditions have been previously reported, and in this paper a psychophysical evaluation of the FDXD detector operating under continuous fluoroscopic conditions is presented. The evaluation technique employed was the threshold contrast detail detectability (TCDD) technique, which enables image quality to be measured on devices operating in the clinical environment. This approach addresses image quality in the context of both the image acquisition and display processes, and uses human observers to measure performance. The Leeds test objects TO[10] and TO[10+] were used to obtain comparative measurements of performance on the FDXD and two digital spot fluorography (DSF) systems, one utilizing a Plumbicon camera and the other a state of the art CCD camera. Measurements were taken at a range of detector entrance exposure rates, namely 6, 12, 25 and 50 (mu) R/s. In order to facilitate comparisons between the systems, all fluoroscopic image processing such as noise reduction algorithms, were disabled during the experiments. At the highest dose rate FDXD significantly outperformed the DSF comparison systems in the TCDD comparisons. At 25 and 12 (mu) R/s all three-systems performed in an equivalent manner and at the lowest exposure rate FDXD was inferior to the two DSF systems. At standard fluoroscopic exposures, FDXD performed in an equivalent

  9. Volume CT with a flat-panel detector on a mobile, isocentric C-arm: pre-clinical investigation in guidance of minimally invasive surgery.

    PubMed

    Siewerdsen, J H; Moseley, D J; Burch, S; Bisland, S K; Bogaards, A; Wilson, B C; Jaffray, D A

    2005-01-01

    A mobile isocentric C-arm (Siemens PowerMobil) has been modified in our laboratory to include a large area flat-panel detector (in place of the x-ray image intensifier), providing multi-mode fluoroscopy and cone-beam computed tomography (CT) imaging capability. This platform represents a promising technology for minimally invasive, image-guided surgical procedures where precision in the placement of interventional tools with respect to bony and soft-tissue structures is critical. The image quality and performance in surgical guidance was investigated in pre-clinical evaluation in image-guided spinal surgery. The control, acquisition, and reconstruction system are described. The reproducibility of geometric calibration, essential to achieving high three-dimensional (3D) image quality, is tested over extended time scales (7 months) and across a broad range in C-arm angulation (up to 45 degrees), quantifying the effect of improper calibration on spatial resolution, soft-tissue visibility, and image artifacts. Phantom studies were performed to investigate the precision of 3D localization (viz., fiber optic probes within a vertebral body) and effect of lateral projection truncation (limited field of view) on soft-tissue detectability in image reconstructions. Pre-clinical investigation was undertaken in a specific spinal procedure (photodynamic therapy of spinal metastases) in five animal subjects (pigs). In each procedure, placement of fiber optic catheters in two vertebrae (L1 and L2) was guided by fluoroscopy and cone-beam CT. Experience across five procedures is reported, focusing on 3D image quality, the effects of respiratory motion, limited field of view, reconstruction filter, and imaging dose. Overall, the intraoperative cone-beam CT images were sufficient for guidance of needles and catheters with respect to bony anatomy and improved surgical performance and confidence through 3D visualization and verification of transpedicular trajectories and tool placement

  10. An investigation of signal performance enhancements achieved through innovative pixel design across several generations of indirect detection, active matrix, flat-panel arrays

    PubMed Central

    Antonuk, Larry E.; Zhao, Qihua; El-Mohri, Youcef; Du, Hong; Wang, Yi; Street, Robert A.; Ho, Jackson; Weisfield, Richard; Yao, William

    2009-01-01

    Active matrix flat-panel imager (AMFPI) technology is being employed for an increasing variety of imaging applications. An important element in the adoption of this technology has been significant ongoing improvements in optical signal collection achieved through innovations in indirect detection array pixel design. Such improvements have a particularly beneficial effect on performance in applications involving low exposures and∕or high spatial frequencies, where detective quantum efficiency is strongly reduced due to the relatively high level of additive electronic noise compared to signal levels of AMFPI devices. In this article, an examination of various signal properties, as determined through measurements and calculations related to novel array designs, is reported in the context of the evolution of AMFPI pixel design. For these studies, dark, optical, and radiation signal measurements were performed on prototype imagers incorporating a variety of increasingly sophisticated array designs, with pixel pitches ranging from 75 to 127 μm. For each design, detailed measurements of fundamental pixel-level properties conducted under radiographic and fluoroscopic operating conditions are reported and the results are compared. A series of 127 μm pitch arrays employing discrete photodiodes culminated in a novel design providing an optical fill factor of ∼80% (thereby assuring improved x-ray sensitivity), and demonstrating low dark current, very low charge trapping and charge release, and a large range of linear signal response. In two of the designs having 75 and 90 μm pitches, a novel continuous photodiode structure was found to provide fill factors that approach the theoretical maximum of 100%. Both sets of novel designs achieved large fill factors by employing architectures in which some, or all of the photodiode structure was elevated above the plane of the pixel addressing transistor. Generally, enhancement of the fill factor in either discrete or continuous

  11. TU-F-18C-02: Increasing Amorphous Selenium Thickness in Direct Conversion Flat-Panel Imagers for Contrast-Enhanced Dual-Energy Breast Imaging

    SciTech Connect

    Scaduto, DA; Hu, Y-H; Zhao, W

    2014-06-15

    Purpose: Contrast-enhanced (CE) breast imaging using iodinated contrast agents requires imaging with x-ray spectra at energies greater than those used in mammography. Optimizing amorphous selenium (a-Se) flat panel imagers (FPI) for this higher energy range may increase lesion conspicuity. Methods: We compare imaging performance of a conventional FPI with 200 μm a-Se conversion layer to a prototype FPI with 300 μm a-Se layer. Both detectors are evaluated in a Siemens MAMMOMAT Inspiration prototype digital breast tomosynthesis (DBT) system using low-energy (W/Rh 28 kVp) and high-energy (W/Cu 49 kVp) x-ray spectra. Detectability of iodinated lesions in dual-energy images is evaluated using an iodine contrast phantom. Effects of beam obliquity are investigated in projection and reconstructed images using different reconstruction methods. The ideal observer signal-to-noise ratio is used as a figure-of-merit to predict the optimal a-Se thickness for CE lesion detectability without compromising conventional full-field digital mammography (FFDM) and DBT performance. Results: Increasing a-Se thickness from 200 μm to 300 μm preserves imaging performance at typical mammographic energies (e.g. W/Rh 28 kVp), and improves the detective quantum efficiency (DQE) for high energy (W/Cu 49 kVp) by 30%. While the more penetrating high-energy x-ray photons increase geometric blur due to beam obliquity in the FPI with thicker a-Se layer, the effect on lesion detectability in FBP reconstructions is negligible due to the reconstruction filters employed. Ideal observer SNR for CE objects shows improvements in in-plane detectability with increasing a-Se thicknesses, though small lesion detectability begins to degrade in oblique projections for a-Se thickness above 500 μm. Conclusion: Increasing a-Se thickness in direct conversion FPI from 200 μm to 300 μm improves lesion detectability in CE breast imaging with virtually no cost to conventional FFDM and DBT. This work was partially

  12. Substantiation Data for Advanced Beaded and Tubular Structural Panels. Volume 3: Testing

    NASA Technical Reports Server (NTRS)

    Hedges, P. C.; Greene, B. E.

    1974-01-01

    The test program is described, which was conducted to provide the necessary experimental data to verify the design and analysis methods developed for beaded and tubular panels. Test results are summarized and presented for all local buckling and full size panel tests. Selected representative test data from each of these tests is presented in detail. The results of this program established a valid analysis and design procedure for circular tube panels. Test results from three other configurations show deformational modes which are not adequately accounted for in the present analyses.

  13. Comparison of an amorphous silicon/cesium iodide flat-panel digital chest radiography system with screen/film and computed radiography systems--a contrast-detail phantom study.

    PubMed

    Rong, X J; Shaw, C C; Liu, X; Lemacks, M R; Thompson, S K

    2001-11-01

    Flat-panel (FP) based digital radiography systems have recently been introduced as a new and improved digital radiography technology; it is important to evaluate and compare this new technology with currently widely used conventional screen/film (SF) and computed radiography (CR) techniques. In this study, the low-contrast performance of an amorphous silicon/cesium iodide (aSi/Csl)-based flat-panel digital chest radiography system is compared to those of a screen/film and a computed radiography system by measuring their contrast-detail curves. Also studied were the effects of image enhancement in printing the digital images and dependence on kVp and incident exposure. It was found that the FP system demonstrated significantly better low-contrast performance than the SF or CR systems. It was estimated that a dose savings of 70%-90% could be achieved to match the low-contrast performance of the FP images to that of the SF images. This dose saving was also found to increase with the object size. No significant difference was observed in low-contrast performances between the SF and CR systems. The use of clinical enhancement protocols for printing digital images was found to be essential and result in better low-contrast performance. No significant effects were observed for different kVps. From the results of this contrast-detail phantom study, the aSi/CsI-based flat-panel digital chest system should perform better under clinical situations for detection of low-contrast objects such as lung nodules. However, proper processing prior to printing would be essential to realizing this better performance.

  14. Interagency Advanced Power Group Solar Photovoltaic Panel Fall meeting minutes, October 22, 1992

    SciTech Connect

    Not Available

    1992-01-01

    This report contains discussions on the following topics: Leaf, TPL, and [sup 60]Co Gamma source testing facilities; in-house photovolatic research effort; US Army's interest developing small thermophotovoatic power source for a variety of missions; charging lead acid batteries with unregulated photovolatic panels; testing of solar array panels for space applications; polycrystalline CuInSe[sub 2] CdTe PV solar cells and, current activities in the US photovolatic program.

  15. Interagency Advanced Power Group Solar Photovoltaic Panel Fall meeting minutes, October 22, 1992

    SciTech Connect

    Not Available

    1992-12-31

    This report contains discussions on the following topics: Leaf, TPL, and {sup 60}Co Gamma source testing facilities; in-house photovolatic research effort; US Army`s interest developing small thermophotovoatic power source for a variety of missions; charging lead acid batteries with unregulated photovolatic panels; testing of solar array panels for space applications; polycrystalline CuInSe{sub 2} & CdTe PV solar cells and, current activities in the US photovolatic program.

  16. Design, development, manufacture, testing, and delivery of devices for connection of solar cell panel circuitry to flat conductor cable solar cell array harness

    NASA Technical Reports Server (NTRS)

    Dillard, P. A.; Waddington, D.

    1971-01-01

    The technology status and problem areas which exist for the application of flat conductor cabling to solar cell arrays are summarized. Details covering the design, connector manufacture, and prototype test results are also summarized.

  17. Close-up of test panels covered with advanced spray-on foam insulation material for the Space Shuttl

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Test panels covered with an advanced foam insulation material for the Space Shuttle's giant external fuel tank were test flown aboard an F-15B research aircraft at NASA's Dryden Flight Research Center, Edwards, Calif. Six panels were mounted on the left side of a heavily instrumented Flight Text Fixture mounted underneath the F-15B's fuselage. Insulation on this panel was finely machined over a horizontal rib structure to simulate in-line airflow past the tank; other panels had the ribs mounted vertically or had the insulation left in a rough as-sprayed surface. The tests were part of an effort by NASA's Marshall Space Flight Center to determine why small particles of the new insulation flaked off the tank on recent Shuttle missions. The tests with Dryden's F-15B were designed to replicate the pressure environment the Shuttle encounters during the first minute after launch. No noticeable erosion of the insulation material was noted after the flight experiment at Dryden.

  18. F-15B in flight with test panels covered with advanced spray-on foam insulation material for the Spa

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Test panels covered with an advanced foam insulation material for the Space Shuttle's giant external fuel tank were test flown aboard an F-15B research aircraft at NASA's Dryden Flight Research Center, Edwards, Calif. Six panels were mounted on the left side of a heavily instrumented Flight Text Fixture mounted underneath the F-15B's fuselage. Insulation on this panel was finely machined over a horizontal rib structure to simulate in-line airflow past the tank; other panels had the ribs mounted vertically or had the insulation left in a rough as-sprayed surface. The tests were part of an effort by NASA's Marshall Space Flight Center to determine why small particles of the new insulation flaked off the tank on recent Shuttle missions. The tests with Dryden's F-15B were designed to replicate the pressure environment the Shuttle encounters during the first minute after launch. No noticeable erosion of the insulation material was noted after the flight experiment at Dryden.

  19. Imaging of Polar Mesosphere Summer Echoes with the 450 MHz Poker Flat Advanced Modular Incoherent Scatter Radar

    NASA Astrophysics Data System (ADS)

    Nicolls, M. J.; Heinselman, C. J.; Hope, E. A.; Ranjan, S.; Kelley, M. C.; Kelly, J. D.

    2007-10-01

    Polar Mesosphere Summer Echoes (PMSE) occur near the mesopause during the polar summer months. PMSE are primarily studied at VHF, however there have been some detections at higher frequencies. Here, we report on some of the first detections of PMSE with the 450 MHz (67 cm) Poker Flat Advanced Modular Incoherent Scatter Radar (PFISR). Echoes were observed with volume reflectivities (radar scattering cross section per unit volume) near 2-3 × 10-17 m-1. On 11 June 2007, PFISR was operating in a 26-beam position mode, with look directions spread over an approximately 80 by 80 km2 region at 85 km altitude with elevation angles as low as ~50°. The measurements showed patchy (tens of kilometer) irregularity regions drifting in from the north, in addition to smaller, more localized structures. There was no evidence for strong aspect sensitivity of these UHF echoes, as PMSE was observed in all look directions with relatively uniform intensity. The observations indicate the presence of fossilized irregularities drifting with the background wind field as well as areas of developing irregularities possibly associated with the presence of active neutral air turbulence.

  20. A research program to reduce interior noise in general aviation airplanes. Influence of depressurization and damping material on the noise reduction characteristics of flat and curved stiffened panels

    NASA Technical Reports Server (NTRS)

    Navaneethan, R.; Streeter, B.; Koontz, S.; Roskam, J.

    1981-01-01

    Some 20 x 20 aluminum panels were studied in a frequency range from 20 Hz to 5000 Hz. The noise sources used were a swept sine wave generator and a random noise generator. The effect of noise source was found to be negligible. Increasing the pressure differential across the panel gave better noise reduction below the fundamental resonance frequency due to an increase in stiffness. The largest increase occurred in the first 1 psi pressure differential. The curved, stiffened panel exhibited similar behavior, but with a lower increase of low frequency noise reduction. Depressurization on these panels resulted in decreased noise reduction at higher frequencies. The effect of damping tapes on the overall noise reduction values of the test specimens was small away from the resonance frequency. In the mass-law region, a slight and proportional improvement in noise reduction was observed by adding damping material. Adding sound absorbtion material to a panel with damping material beneficially increased noise reduction at high frequencies.

  1. Development of Surfaces Optically Suitable for Flat Solar Panels. [using a reflectometer which separately evaluates spectral and diffuse reflectivities of surfaces

    NASA Technical Reports Server (NTRS)

    1979-01-01

    A reflectometer which can separately evaluate the spectral and diffuse reflectivities of surfaces is described. A phase locked detection system for the reflectometer is also described. A selective coating on aluminum potentially useful for flat plate solar collector applications is presented. The coating is composed of strongly bound copper oxide (divalent) and is formed by an etching process performed on an aluminum alloy with high copper content. Fabrication costs are expected to be small due to the one stop fabrication process. A number of conclusions gathered from the literature as to the required optical properties of flat plate solar collectors are discussed.

  2. Dose reduction in skeletal and chest radiography using a large-area flat-panel detector based on amorphous silicon and thallium-doped cesium iodide: technical background, basic image quality parameters, and review of the literature.

    PubMed

    Völk, Markus; Hamer, Okka W; Feuerbach, Stefan; Strotzer, Michael

    2004-05-01

    The two most frequently performed diagnostic X-ray examinations are those of the extremities and of the chest. Thus, dose reduction in the field of conventional skeletal and chest radiography is an important issue and there is a need to reduce man-made ionizing radiation. The large-area flat-panel detector based on amorphous silicon and thallium-doped cesium iodide provides a significant reduction of radiation dose in skeletal and chest radiography compared with traditional imaging systems. This article describes the technical background and basic image quality parameters of this 43 x 43-cm digital system, and summarizes the available literature (years 2000-2003) concerning dose reduction in experimental and clinical studies. Due to its high detective quantum efficiency and dynamic range compared with traditional screen-film systems, a dose reduction of up to 50% is possible without loss of image quality.

  3. Hypervelocity Impact (HVI). Volume 2; WLE Small-Scale Fiberglass Panel Flat Multi-Layer Targets A-1, A-2, and B-1

    NASA Technical Reports Server (NTRS)

    Gorman, Michael R.; Ziola, Steven M.

    2007-01-01

    During 2003 and 2004, the Johnson Space Center's White Sands Testing Facility in Las Cruces, New Mexico conducted hypervelocity impact tests on the space shuttle wing leading edge. Hypervelocity impact tests were conducted to determine if Micro-Meteoroid/Orbital Debris impacts could be reliably detected and located using simple passive ultrasonic methods. The objective of Targets A-1, A-2, and B-2 was to study hypervelocity impacts through multi-layered panels simulating Whipple shields on spacecraft. Impact damage was detected using lightweight, low power instrumentation capable of being used in flight.

  4. Beyond BRAF(V600): clinical mutation panel testing by next-generation sequencing in advanced melanoma.

    PubMed

    Siroy, Alan E; Boland, Genevieve M; Milton, Denái R; Roszik, Jason; Frankian, Silva; Malke, Jared; Haydu, Lauren; Prieto, Victor G; Tetzlaff, Michael; Ivan, Doina; Wang, Wei-Lien; Torres-Cabala, Carlos; Curry, Jonathan; Roy-Chowdhuri, Sinchita; Broaddus, Russell; Rashid, Asif; Stewart, John; Gershenwald, Jeffrey E; Amaria, Rodabe N; Patel, Sapna P; Papadopoulos, Nicholas E; Bedikian, Agop; Hwu, Wen-Jen; Hwu, Patrick; Diab, Adi; Woodman, Scott E; Aldape, Kenneth D; Luthra, Rajyalakshmi; Patel, Keyur P; Shaw, Kenna R; Mills, Gordon B; Mendelsohn, John; Meric-Bernstam, Funda; Kim, Kevin B; Routbort, Mark J; Lazar, Alexander J; Davies, Michael A

    2015-02-01

    The management of melanoma has evolved owing to improved understanding of its molecular drivers. To augment the current understanding of the prevalence, patterns, and associations of mutations in this disease, the results of clinical testing of 699 advanced melanoma patients using a pan-cancer next-generation sequencing (NGS) panel of hotspot regions in 46 genes were reviewed. Mutations were identified in 43 of the 46 genes on the panel. The most common mutations were BRAFV600 (36%), NRAS (21%), TP53 (16%), BRAFNon-V600 (6%), and KIT (4%). Approximately one-third of melanomas had >1 mutation detected, and the number of mutations per tumor was associated with melanoma subtype. Concurrent TP53 mutations were the most frequent events in tumors with BRAFV600 and NRAS mutations. Melanomas with BRAFNon-V600mutations frequently harbored concurrent NRAS mutations (18%), which were rare in tumors with BRAFV600 mutations (1.6%). The prevalence of BRAFV600 and KIT mutations were significantly associated with melanoma subtypes, and BRAFV600 and TP53 mutations were significantly associated with cutaneous primary tumor location. Multiple potential therapeutic targets were identified in metastatic unknown primary and cutaneous melanomas that lacked BRAFV600 and NRAS mutations. These results enrich our understanding of the patterns and clinical associations of oncogenic mutations in melanoma.

  5. Advancing research on endocrine disrupting chemicals in breast cancer: Expert panel recommendations.

    PubMed

    Teitelbaum, Susan L; Belpoggi, Fiorella; Reinlib, Les

    2015-07-01

    Breast cancer incidence continues to increase in the US and Europe, a reflection of the growing influence of environment factors that interact with personal genetics. The US Environmental Protection Agency estimates that there are approximately 10,000 endocrine disrupting chemicals among the common daily exposures that could affect the risk of disease. The daunting tasks of identifying, characterizing, and elucidating the mechanisms of endocrine disrupting chemicals in breast cancer need to be addressed to produce a comprehensive model that will facilitate preventive strategies and public policy. An expert panel met to describe and bring attention to needs linking common environmental exposures, critical windows of exposure, and optimal times of assessment in investigating breast cancer risk. The group included investigators with extensive experience in the use of rodent models and in leading population studies and produced a set of recommendations for effective approaches to gaining insights into the environmental origins of breast cancer across the lifespan.

  6. Photovoltaic panel support assembly

    SciTech Connect

    Barker, J.M.; Underwood, J.C.; Shingleton, J.

    1993-07-20

    A solar energy electrical power source is described comprising in combination at least two flat photovoltaic panels disposed side-by-side in co-planar relation with one another, a pivot shaft extending transversely across the panels, at least two supports spaced apart lengthwise of the pivot shaft, means for connecting the pivot shaft to the at least two supports, attachment means for connecting the at least two panels to the pivot shaft so that the panels can pivot about the longitudinal axis of the shaft, coupling means mechanically coupling all of the panels together so as to form a unified flat array, and selectively operable drive means for mechanically pivoting the unified flat array about the axis; wherein each of the flat photovoltaic panels comprises at least two modules each comprising a plurality of electrically interconnected photovoltaic cells, the at least two modules being aligned along a line extending at a right angle to the pivot shaft, and the coupling means comprises (a) an elongate member extending parallel to and spaced from the pivot shaft and (b) means for attaching the elongate member to the panels; and further wherein each flat photovoltaic panel comprises a unitary frame consisting of a pair of end frame members extending parallel to the pivot shaft, a pair of side frame members extending between and connected to the end frame members, and a pair of spaced apart cross frame members, with one of the two modules being embraced by and secured to the side frame members and a first one of each of the end and cross frame members, and the other of the two modules being embraced by and secured to the side frame members and the second one of each of the end and cross frame members, whereby the gap created by the spaced apart cross frame members allow air to pass between them in order to reduce the sail effect when the solar array is subjected to buffeting winds.

  7. An indirect flat-panel detector with avalanche gain for low dose x-ray imaging: SAPHIRE (scintillator avalanche photoconductor with high resolution emitter readout)

    NASA Astrophysics Data System (ADS)

    Zhao, Wei; Li, Dan; Rowlands, J. A.; Egami, N.; Takiguchi, Y.; Nanba, M.; Honda, Y.; Ohkawa, Y.; Kubota, M.; Tanioka, K.; Suzuki, K.; Kawai, T.

    2008-03-01

    An indirect flat-imager with programmable avalanche gain and field emitter array (FEA) readout is being investigated for low-dose x-ray imaging with high resolution. It is made by optically coupling a structured x-ray scintillator CsI (Tl) to an amorphous selenium (a-Se) avalanche photoconductor called HARP (high-gain avalanche rushing photoconductor). The charge image created by HARP is read out by electron beams generated by the FEA. The proposed detector is called SAPHIRE (Scintillator Avalanche Photoconductor with HIgh Resolution Emitter readout). The avalanche gain of HARP depends on both a-Se thickness and applied electric field E Se. At E Se of > 80 V/μm, the avalanche gain can enhance the signal at low dose (e.g. fluoroscopy) and make the detector x-ray quantum noise limited down to a single x-ray photon. At high exposure (e.g. radiography), the avalanche gain can be turned off by decreasing E Se to < 70 V/μm. In this paper the imaging characteristics of the FEA readout method, including the spatial resolution and noise, were investigated experimentally using a prototype optical HARP-FEA image sensor. The potential x-ray imaging performance of SAPHIRE, especially the aspect of programmable gain to ensure wide dynamic range and x-ray quantum noise limited performance at the lowest exposure in fluoroscopy, was investigated.

  8. A roadmap towards advanced space weather science to protect society's technological infrastructure: Panel Discussion 2

    NASA Astrophysics Data System (ADS)

    Schrijver, Carolus; Kauristie, Kirsti

    This single 90minute slot will follow on from the morning plenary presentation of the roadmap, providing an opportunity for further discussion of the panel’s findings with an invited panel of key stakeholders. --- As mankind’s technological capabilities grow, society constructs a rapidly deepening insight into the workings of the universe at large, being guided by exploring space near to our home. But at the same time our societal dependence on technology increases and with that comes a growing appreciation of the challenges presented by the phenomena that occur in that space around our home planet: Magnetic explosions on the Sun and their counterparts in the geomagnetic field can in extreme cases endanger our all-pervasive electrical infrastructure. Powerful space storms occasionally lower the reliability of the globe-spanning satellite navigation systems and interrupt radio communications. Energetic particle storms lead to malfunctions and even failures in satellites that are critical to the flow of information in the globally connected economies. These and other Sun-driven effects on Earth’s environment, collectively known as space weather, resemble some other natural hazards in the sense that they pose a risk for the safe and efficient functioning of society that needs to be understood, quantified, and - ultimately - mitigated against. The complexity of the coupled Sun-Earth system, the sparseness by which it can be covered by remote-sensing and in-situ instrumentation, and the costs of the required observational and computational infrastructure warrant a well-planned and well-coordinated approach with cost-efficient solutions. Our team is tasked with the development of a roadmap with the goal of demonstrably improving our observational capabilities, scientific understanding, and the ability to forecast. This paper summarizes the accomplishments of the roadmap team in identifying the highest-priority challenges to achieve these goals.

  9. A roadmap towards advanced space weather science to protect society's technological infrastructure: Panel Discussion 1

    NASA Astrophysics Data System (ADS)

    Schrijver, Carolus; Kauristie, Kirsti

    This single 90minute slot will follow on from the morning plenary presentation of the roadmap, providing an opportunity for further discussion of the panel’s findings with an invited panel of key stakeholders. --- As mankind’s technological capabilities grow, society constructs a rapidly deepening insight into the workings of the universe at large, being guided by exploring space near to our home. But at the same time our societal dependence on technology increases and with that comes a growing appreciation of the challenges presented by the phenomena that occur in that space around our home planet: Magnetic explosions on the Sun and their counterparts in the geomagnetic field can in extreme cases endanger our all-pervasive electrical infrastructure. Powerful space storms occasionally lower the reliability of the globe-spanning satellite navigation systems and interrupt radio communications. Energetic particle storms lead to malfunctions and even failures in satellites that are critical to the flow of information in the globally connected economies. These and other Sun-driven effects on Earth’s environment, collectively known as space weather, resemble some other natural hazards in the sense that they pose a risk for the safe and efficient functioning of society that needs to be understood, quantified, and - ultimately - mitigated against. The complexity of the coupled Sun-Earth system, the sparseness by which it can be covered by remote-sensing and in-situ instrumentation, and the costs of the required observational and computational infrastructure warrant a well-planned and well-coordinated approach with cost-efficient solutions. Our team is tasked with the development of a roadmap with the goal of demonstrably improving our observational capabilities, scientific understanding, and the ability to forecast. This paper summarizes the accomplishments of the roadmap team in identifying the highest-priority challenges to achieve these goals.

  10. A roadmap towards advanced space weather science to protect society's technological infrastructure: Panel Discussion 3

    NASA Astrophysics Data System (ADS)

    Schrijver, Carolus; Kauristie, Kirsti

    This single 90minute slot will follow on from the morning plenary presentation of the roadmap, providing an opportunity for further discussion of the panel’s findings with an invited panel of key stakeholders. --- As mankind’s technological capabilities grow, society constructs a rapidly deepening insight into the workings of the universe at large, being guided by exploring space near to our home. But at the same time our societal dependence on technology increases and with that comes a growing appreciation of the challenges presented by the phenomena that occur in that space around our home planet: Magnetic explosions on the Sun and their counterparts in the geomagnetic field can in extreme cases endanger our all-pervasive electrical infrastructure. Powerful space storms occasionally lower the reliability of the globe-spanning satellite navigation systems and interrupt radio communications. Energetic particle storms lead to malfunctions and even failures in satellites that are critical to the flow of information in the globally connected economies. These and other Sun-driven effects on Earth’s environment, collectively known as space weather, resemble some other natural hazards in the sense that they pose a risk for the safe and efficient functioning of society that needs to be understood, quantified, and - ultimately - mitigated against. The complexity of the coupled Sun-Earth system, the sparseness by which it can be covered by remote-sensing and in-situ instrumentation, and the costs of the required observational and computational infrastructure warrant a well-planned and well-coordinated approach with cost-efficient solutions. Our team is tasked with the development of a roadmap with the goal of demonstrably improving our observational capabilities, scientific understanding, and the ability to forecast. This paper summarizes the accomplishments of the roadmap team in identifying the highest-priority challenges to achieve these goals.

  11. Scintillator high-gain avalanche rushing photoconductor active-matrix flat panel imager: Zero-spatial frequency x-ray imaging properties of the solid-state SHARP sensor structure

    SciTech Connect

    Wronski, M.; Zhao, W.; Tanioka, K.; DeCrescenzo, G.; Rowlands, J. A.

    2012-11-15

    Purpose: The authors are investigating the feasibility of a new type of solid-state x-ray imaging sensor with programmable avalanche gain: scintillator high-gain avalanche rushing photoconductor active matrix flat panel imager (SHARP-AMFPI). The purpose of the present work is to investigate the inherent x-ray detection properties of SHARP and demonstrate its wide dynamic range through programmable gain. Methods: A distributed resistive layer (DRL) was developed to maintain stable avalanche gain operation in a solid-state HARP. The signal and noise properties of the HARP-DRL for optical photon detection were investigated as a function of avalanche gain both theoretically and experimentally, and the results were compared with HARP tube (with electron beam readout) used in previous investigations of zero spatial frequency performance of SHARP. For this new investigation, a solid-state SHARP x-ray image sensor was formed by direct optical coupling of the HARP-DRL with a structured cesium iodide (CsI) scintillator. The x-ray sensitivity of this sensor was measured as a function of avalanche gain and the results were compared with the sensitivity of HARP-DRL measured optically. The dynamic range of HARP-DRL with variable avalanche gain was investigated for the entire exposure range encountered in radiography/fluoroscopy (R/F) applications. Results: The signal from HARP-DRL as a function of electric field showed stable avalanche gain, and the noise associated with the avalanche process agrees well with theory and previous measurements from a HARP tube. This result indicates that when coupled with CsI for x-ray detection, the additional noise associated with avalanche gain in HARP-DRL is negligible. The x-ray sensitivity measurements using the SHARP sensor produced identical avalanche gain dependence on electric field as the optical measurements with HARP-DRL. Adjusting the avalanche multiplication gain in HARP-DRL enabled a very wide dynamic range which encompassed all

  12. Performance of a new digital flat-panel detector system in the detection of simulated rheumatoid erosions: a comparison with a speed-class 200 screen-film system, a mammography screen-film system, and a storage-phosphor system at different levels of exposure.

    NASA Astrophysics Data System (ADS)

    Ludwig, Karl; Henschel, Andreas; Bernhardt, Thomas; Lenzen, Horst; Wormanns, Dag; Diederich, Stefan; Heindel, Walter

    2002-05-01

    The purpose of this study was to compare a large-area direct read-out flat-panel detector system with a speed class 200 screen-film system, a storage-phosphor system and a mammography screen-film system with regard to the detection of simulated rheumatoid erosions and to assess its diagnostic performance with decreasing exposure dose. The performance of a flat-panel system in such small lesions was considered especially interesting, as the spatial resolution of this system, limited by its pixel size, is considerably lower than that of conventional screen-film systems. An animal model with 160 joint specimens from 20 monkey paws was used. 640 regions were defined in these 160 meta- carpophalangeal and proximal interphalangeal joint specimens. Simulated rheumatoid erosions were created in 320 of these 640 regions. Specimens were enclosed in containers filed with water to obtain absorption and scatter radiation conditions similar to a human hand. Imaging was performed using a flat-panel system, a sped class 200 screen-film system, a mammography screen-film system and a storage- phosphor system under exactly matched conditions. Different exposure doses equivalent to speed classes of S equals 100, 200, 400, 800, 1600 and 3200 were used. Presence or absence of a lesion was assessed by three radiologists using a five level confidence scale. Receiver operating characteristic analysis was performed for a total of 21,120 observations and diagnostic performance estimated by the area under the ROC curve. The significance of differences between Az values was tested with analysis of variance. ROC-analysis showed Az values of 0.809, 0.768, 0.737, 0.710 and 0.685 for the flat-panel system, 0.770 for the screen-film system, 0.781, 0.739, 0.724 and 0.680 for the storage-phosphor system, and 0.798 for the mammography screen-film system. Analysis of variance showed significant differences for certain combinations of imaging modalities and exposure doses. The diagnostic performance of

  13. Treatment for Addiction: Advancing the Common Good. Recommendations from a Join Together Policy Panel on Treatment and Recovery.

    ERIC Educational Resources Information Center

    Join Together, Boston, MA.

    Join Together convened a panel of experts to review U.S. policies for addiction treatment and recovery. Although the panel reached an agreement on six recommendations for policy changes that can make help more accessible and expand treatment to more people. These recommendations are: (1) treatment for alcoholism and other drug addiction must be…

  14. Design and fabrication of Rene 41 advanced structural panels. [their performance under axial compression, shear, and bending loads

    NASA Technical Reports Server (NTRS)

    Greene, B. E.; Northrup, R. F.

    1975-01-01

    The efficiency was investigated of curved elements in the design of lightweight structural panels under combined loads of axial compression, inplane shear, and bending. The application is described of technology generated in the initial aluminum program to the design and fabrication of Rene 41 panels for subsequent performance tests at elevated temperature. Optimum designs for two panel configurations are presented. The designs are applicable to hypersonic airplane wing structure, and are designed specifically for testing at elevated temperature in the hypersonic wing test structure located at the NASA Flight Research Center. Fabrication methods developed to produce the Rene panels are described, and test results of smaller structural element specimens are presented to verify the design and fabrication methods used. Predicted strengths of the panels under several proposed elevated temperature test load conditions are presented.

  15. Fabrication and physical testing of graphite composite panels utilizing woven graphite fabric with current and advanced state-of-the-art resin systems

    NASA Technical Reports Server (NTRS)

    Lee, S. C. S.

    1979-01-01

    Three weaves were evaluated; a balanced plain weave, a balanced 8-harness satin weave, and a semiunidirectional crowfoot satin weave. The current state-of-the-art resin system selected was Fiberite's 934 Epoxy; the advanced resin systems evaluated were Phenolic, Phenolic/Novolac, Benzyl and Bismaleimide. The panels were fabricated for testing on NASA/Ames Research Center's Composites Modification Program. Room temperature mechanical tests only were performed by Hitco; the results are presented.

  16. Piezoceramic Actuator Placement for Acoustic Control of Panels

    NASA Technical Reports Server (NTRS)

    Bevan, Jeffrey S.

    2000-01-01

    Optimum placement of multiple traditional piezoceramic actuators is determined for active structural acoustic control of flat panels. The structural acoustic response is determined using acoustic radiation filters and structural surface vibration characteristics. Linear Quadratic Regulator (LQR) control is utilized to determine the optimum state feedback gain for active structural acoustic control. The optimum actuator location is determined by minimizing the structural acoustic radiated noise using a modified genetic algorithm. Experimental tests are conducted and compared to analytical results. Anisotropic piezoceramic actuators exhibit enhanced performance when compared to traditional isotropic piezoceramic actuators. As a result of the inherent isotropy, these advanced actuators develop strain along the principal material axis. The orientation of anisotropic actuators is investigated on the effect of structural vibration and acoustic control of curved and flat panels. A fully coupled shallow shell finite element formulation is developed to include anisotropic piezoceramic actuators for shell structures.

  17. Piezoceramic Actuator Placement for Acoustic Control of Panels

    NASA Technical Reports Server (NTRS)

    Bevan, Jeffrey S.; Turner, Travis L. (Technical Monitor)

    2001-01-01

    Optimum placement of multiple traditional piezoceramic actuators is determined for active structural acoustic control of flat panels. The structural acoustic response is determined using acoustic radiation filters and structural surface vibration characteristics. Linear Quadratic Regulator (LQR) control is utilized to determine the optimum state feedback gain for active structural acoustic control. The optimum actuator location is determined by minimizing the structural acoustic radiated noise using a modified genetic algorithm. Experimental tests are conducted and compared to analytical results. Anisotropic piezoceramic actuators exhibits enhanced performance when compared to traditional isotropic piezoceramic actuators. As a result of the inherent isotropy, these advanced actuators develop strain along the principal material axis. The orientation of anisotropic actuators is investigated on the effect of structural vibration and acoustic control of curved and flat panels. A fully coupled shallow shell finite element formulation is developed to include anisotropic piezoceramic actuators for shell structures.

  18. Investigation into the influence of x-ray scatter on the imaging performance of an x-ray flat-panel imager-based cone-beam volume CT

    NASA Astrophysics Data System (ADS)

    Tang, Xiangyang; Ning, Ruola; Yu, Rongfeng; Conover, David L.

    2001-06-01

    The advent of the x-ray flat panel imager (FPI) is making the study of cone beam volume CT (CBVCT) more competitive. Motivated by recent encouraging developments in CBVCT, this paper investigates the influence of x-ray scatter on the imaging performance of an x-ray FPI based CBVCT prototype. The prototype employs a circle-plus-two-arc orbit to meet the data sufficiency condition, and can reconstruct a region of interest within a longitudinally unbounded object using a cone beam filtered back-projection algorithm derived for the data acquisition orbit. First, the humanoid phantom is used to investigate the temporal variation of both scatter intensity and scatter to primary ratio (SPR) in the projection images acquired for CB reconstruction. Second, a 160 mm cylindrical water phantom consisting of four 16 mm rods made up of Acrylic, Polyethelene, Polycarborate and Polystrene respectively is utilized to evaluate the variation of interference caused by x-ray scatter (cupping effect) and signal to noise ratio vs. SPR in projection images. Third, a disc phantom consisting of seven acrylic discs stacked at even intervals is employed to evaluate the influence of x-ray scatter on reconstruction accuracy and the improvement of CBVCT image quality with recourse to an anti-scatter grid. Finally, the alleviation of the cupping effect in the presence of a beam-shaping (bow-tie) attenuator is assessed . The quantitative investigation shows that the influence of x-ray scatter on the SNR and CT number accuracy is a crucial problem to be addressed for the application of x-ray CBVCT.

  19. Should 3K zoom function be used for detection of pneumothorax in cesium iodide/amorphous silicon flat-panel detector radiographs presented on 1K-matrix soft copies?

    PubMed

    Herrmann, Karin A; Bonél, H M; Stäbler, A; Voelk, M; Strotzer, M; Zech, C J; Reiser, M F

    2006-12-01

    The purpose of the study was to evaluate observer performance in the detection of pneumothorax with cesium iodide and amorphous silicon flat-panel detector radiography (CsI/a-Si FDR) presented as 1K and 3K soft-copy images. Forty patients with and 40 patients without pneumothorax diagnosed on previous and subsequent digital storage phosphor radiography (SPR, gold standard) had follow-up chest radiographs with CsI/a-Si FDR. Four observers confirmed or excluded the diagnosis of pneumothorax according to a five-point scale first on the 1K soft-copy image and then with help of 3K zoom function (1K monitor). Receiver operating characteristic (ROC) analysis was performed for each modality (1K and 3K). The area under the curve (AUC) values for each observer were 0.7815, 0.7779, 0.7946 and 0.7066 with 1K-matrix soft copies and 0.8123, 0.7997, 0.8078 and 0.7522 with 3K zoom. Overall detection of pneumothorax was better with 3K zoom. Differences between the two display methods were not statistically significant in 3 of 4 observers (p-values between 0.13 and 0.44; observer 4: p = 0.02). The detection of pneumothorax with 3K zoom is better than with 1K soft copy but not at a statistically significant level. Differences between both display methods may be subtle. Still, our results indicate that 3K zoom should be employed in clinical practice.

  20. Radiation Exposure in Biliary Procedures Performed to Manage Anastomotic Strictures in Pediatric Liver Transplant Recipients: Comparison Between Radiation Exposure Levels Using an Image Intensifier and a Flat-Panel Detector-Based System

    SciTech Connect

    Miraglia, Roberto Maruzzelli, Luigi; Tuzzolino, Fabio; Indovina, Pietro Luigi; Luca, Angelo

    2013-12-15

    Purpose: The aim of this study was to estimate radiation exposure in pediatric liver transplants recipients who underwent biliary interventional procedures and to compare radiation exposure levels between biliary interventional procedures performed using an image intensifier-based angiographic system (IIDS) and a flat panel detector-based interventional system (FPDS). Materials and Methods: We enrolled 34 consecutive pediatric liver transplant recipients with biliary strictures between January 2008 and March 2013 with a total of 170 image-guided procedures. The dose-area product (DAP) and fluoroscopy time was recorded for each procedure. The mean age was 61 months (range 4-192), and mean weight was 17 kg (range 4-41). The procedures were classified into three categories: percutaneous transhepatic cholangiography and biliary catheter placement (n = 40); cholangiography and balloon dilatation (n = 55); and cholangiography and biliary catheter change or removal (n = 75). Ninety-two procedures were performed using an IIDS. Seventy-eight procedures performed after July 2010 were performed using an FPDS. The difference in DAP between the two angiographic systems was compared using Wilcoxon rank-sum test and a multiple linear regression model. Results: Mean DAP in the three categories was significantly greater in the group of procedures performed using the IIDS compared with those performed using the FPDS. Statistical analysis showed a p value = 0.001 for the PTBD group, p = 0.0002 for the cholangiogram and balloon dilatation group, and p = 0.00001 for the group with cholangiogram and biliary catheter change or removal. Conclusion: In our selected cohort of patients, the use of an FPDS decreases radiation exposure.

  1. Flat-Panel Cone-Beam Ct-Guided Radiofrequency Ablation of Very Small (≤1.5 cm) Liver Tumors: Technical Note on a Preliminary Experience

    SciTech Connect

    Cazzato, Roberto Luigi Buy, Xavier Alberti, Nicolas Fonck, Mariane; Grasso, Rosario Francesco; Palussière, Jean

    2015-02-15

    PurposeThe aim of the present study was to investigate the technical feasibility of flat-panel cone-beam CT (CBCT)-guided radiofrequency ablation (RFA) of very small (<1.5 cm) liver tumors.Materials and MethodsPatients included were candidates for hepatic percutaneous RFA as they had single biopsy-proven hepatic tumors sized ≤1.5 cm and poorly defined on ultrasonography. Following apnea induction, unenhanced CBCT scans were acquired and used to deploy the RF electrode with the aid of a virtual navigation system. If the tumor was not clearly identified on the unenhanced CBCT scan, a right retrograde arterial femoral access was established to carry out hepatic angiography and localize the tumor. Patients’ lesions and procedural variables were recorded and analyzed.ResultsThree patients (2 male and 1 female), aged 68, 76, and 87 years were included; 3 lesions (2 hepato-cellular carcinoma and 1 metastasis from colorectal cancer) were treated. One patient required hepatic angiography. Cycles of apnea used to acquire CBCT images and to deploy the electrode lasted <120 s. Mean fluoroscopic time needed to deploy the electrode was 36.6 ± 5.7 min. Mean overall procedural time was 66.0 ± 22.9 min. No peri- or post-procedural complications were noted. No cases of incomplete ablation were noted at 1-month follow-up.ConclusionPercutaneous CBCT-guided liver RFA with or without arterial hepatic angiography is technically feasible.

  2. National Center for Advanced Information Components Manufacturing. Program summary report, Volume II

    SciTech Connect

    1996-10-01

    The National Center for Advanced Information Components Manufacturing focused on manufacturing research and development for flat panel displays, advanced lithography, microelectronics, and optoelectronics. This report provides an overview of the program, program history, summaries of the technical projects, and key program accomplishments.

  3. F-15B in on ramp with close-up of test panels covered with advanced spray-on foam insulation materia

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Test panels covered with an advanced foam insulation material for the Space Shuttle's giant external fuel tank were test flown aboard an F-15B research aircraft at NASA's Dryden Flight Research Center, Edwards, Calif. Six panels were mounted on the left side of a heavily instrumented Flight Text Fixture mounted underneath the F-15B's fuselage. Insulation on this panel was finely machined over a horizontal rib structure to simulate in-line airflow past the tank; other panels had the ribs mounted vertically or had the insulation left in a rough as-sprayed surface. The tests were part of an effort by NASA's Marshall Space Flight Center to determine why small particles of the new insulation flaked off the tank on recent Shuttle missions. The tests with Dryden's F-15B were designed to replicate the pressure environment the Shuttle encounters during the first minute after launch. No noticeable erosion of the insulation material was noted after the flight experiment at Dryden.

  4. A new flat sheet membrane bioreactor hybrid system for advanced treatment of effluent, reverse osmosis pretreatment and fouling mitigation.

    PubMed

    Hosseinzadeh, Majid; Bidhendi, Gholamreza Nabi; Torabian, Ali; Mehrdadi, Naser; Pourabdullah, Mehdi

    2015-09-01

    This paper introduces a new hybrid electro membrane bioreactor (HEMBR) for reverse osmosis (RO) pretreatment and advanced treatment of effluent by simultaneously integrating electrical coagulation (EC) with a membrane bioreactor (MBR) and its performance was compared with conventional MBR. Experimental results and their statistical analysis showed removal efficiency for suspended solids (SS) of almost 100% for both reactors. HEMBR removal of chemical oxygen demand (COD) improved by 4% and membrane fouling was alleviated according to transmembrane pressure (TMP). The average silt density index (SDI) of HEMBR permeate samples was slightly better indicating less RO membrane fouling. Moreover, based on the SVI comparison of two reactor biomass samples, HEMBR showed better settling characteristics which improved the dewaterability and filterability of the sludge. Analysis the change of membrane surfaces and the cake layer formed over them through field emission scanning electron microscopy (FESEM) and X-ray fluorescence spectrometer (XRF) were also discussed.

  5. INCREASING OIL RECOVERY THROUGH ADVANCED REPROCESSING OF 3D SEISMIC, GRANT CANYON AND BACON FLAT FIELDS, NYE COUNTY, NEVADA

    SciTech Connect

    Eric H. Johnson; Don E. French

    2001-06-01

    Makoil, Inc., of Orange, California, with the support of the U.S. Department of Energy has reprocessed and reinterpreted the 3D seismic survey of the Grant Canyon area, Railroad Valley, Nye County, Nevada. The project was supported by Dept. of Energy Grant DE-FG26-00BC15257. The Grant Canyon survey covers an area of 11 square miles, and includes Grant Canyon and Bacon Flat oil fields. These fields have produced over 20 million barrels of oil since 1981, from debris slides of Devonian rocks that are beneath 3,500 to 5,000 ft of Tertiary syntectonic deposits that fill the basin of Railroad Valley. High-angle and low-angle normal faults complicate the trap geometry of the fields, and there is great variability in the acoustic characteristics of the overlying valley fill. These factors combine to create an area that is challenging to interpret from seismic reflection data. A 3D seismic survey acquired in 1992-93 by the operator of the fields has been used to identify development and wildcat locations with mixed success. Makoil believed that improved techniques of processing seismic data and additional well control could enhance the interpretation enough to improve the chances of success in the survey area. The project involved the acquisition of hardware and software for survey interpretation, survey reprocessing, and reinterpretation of the survey. SeisX, published by Paradigm Geophysical Ltd., was chosen as the interpretation software, and it was installed on a Dell Precision 610 computer work station with the Windows NT operating system. The hardware and software were selected based on cost, possible addition of compatible modeling software in the future, and the experience of consulting geophysicists in the Billings area. Installation of the software and integration of the hardware into the local office network was difficult at times but was accomplished with some technical support from Paradigm and Hewlett Packard, manufacturer of some of the network equipment. A

  6. Combination of three-gene immunohistochemical panel and magnetic resonance imaging-detected extramural vascular invasion to assess prognosis in non-advanced rectal cancer patients

    PubMed Central

    Li, Xiao-Fu; Jiang, Zheng; Gao, Ying; Li, Chun-Xiang; Shen, Bao-Zhong

    2016-01-01

    AIM To identify a small, clinically applicable immunohistochemistry (IHC) panel that could be combined with magnetic resonance imaging (MRI)-detected extramural vascular invasion (EMVI) for assessment of prognosis concerning the non-advanced rectal cancer patients prior to operation. METHODS About 329 patients with pathologically confirmed rectal carcinoma (RC) were screened in this research, all of whom had been examined via an MRI and were treatment-naïve from July 2011 to July 2014. The candidate proteins that were reported to be altered by RC were examined in tissues by IHC. All chosen samples were adopted from the fundamental cores of histopathologically confirmed carcinomas during the initial surgeries. RESULTS Of the three proteins that were tested, c-MYC, PCNA and TIMP1 were detected with relatively significant expression in tumors, 35.9%, 23.7% and 58.7% respectively. The expression of the three proteins were closely connected with prognosis (P = 0.032, 0.003, 0.021). The patients could be classified into different outcome groups according to an IHC panel (P < 0.01) via these three proteins. Taking into consideration known survival covariates, especially EMVI, the IHC panel served as an independent prognostic factor. The EMVI combined with the IHC panel could categorize patients into different prognostic groups with distinction (P < 0.01). CONCLUSION These studies argue that this three-protein panel of c-MYC, PCNA, coupled with TIMP1 combined with MRI-detected EMVI could offer extra prognostic details for preoperative treatment of RC. PMID:27784970

  7. Aerothermodynamic Assessment of Corrugated Panel Thermal Protection Systems

    NASA Technical Reports Server (NTRS)

    Brandon, H. J.; Britt, A. H.; Kipp, H. W.; Masek, R. V.

    1978-01-01

    The feasibility of using corrugated panels as a thermal protection system for an advanced space transportation vehicle was investigated. The study consisted of two major tasks: development of improved correlations for wind tunnel heat transfer and pressure data to yield design techniques, and application of the design techniques to determine if corrugated panels have application future aerospace vehicles. A single-stage-to-orbit vehicle was used to assess advantages and aerothermodynamic penalties associated with use of such panels. In the correlation task, experimental turbulent heat transfer and pressure data obtained on corrugation roughened surfaces during wind tunnel testing were analyzed and compared with flat plate data. The correlations and data comparisons included the effects of a large range of geometric, inviscid flow, internal boundary layer, and bulk boundary layer parameters in supersonic and hypersonic flow.

  8. SU-E-I-53: Comparison of Kerma-Area-Product Between the Micro-Angiographic Fluoroscope (MAF) and a Flat Panel Detector (FPD) as Used in Neuro-Endovascular Procedures

    SciTech Connect

    Vijayan, S; Rana, V; Nagesh, S Setlur; Xiong, Z; Rudin, S; Bednarek, D

    2015-06-15

    Purpose: To determine the reduction of integral dose to the patient when using the micro-angiographic fluoroscope (MAF) compared to when using the standard flat-panel detector (FPD) for the techniques used during neurointerventional procedures. Methods: The MAF is a small field-of-view, high resolution x-ray detector which captures 1024 x 1024 pixels with an effective pixel size of 35μm and is capable of real-time imaging up to 30 frames per second. The MAF was used in neuro-interventions during those parts of the procedure when high resolution was needed and the FPD was used otherwise. The technique parameters were recorded when each detector was used and the kerma-area-product (KAP) per image frame was determined. KAP values were calculated for seven neuro interventions using premeasured calibration files of output as a function of kVp and beam filtration and included the attenuation of the patient table for the frontal projections to be more representative of integral patient dose. The air kerma at the patient entrance was multiplied by the beam area at that point to obtain the KAP values. The ranges of KAP values per frame were determined for the range of technique parameters used during the clinical procedures. To appreciate the benefit of the higher MAF resolution in the region of interventional activity, DA technique parameters were generally used with the MAF. Results: The lowest and highest values of KAP per frame for the MAF in DA mode were 4 and 50 times lower, respectively, compared to those of the FPD in pulsed fluoroscopy mode. Conclusion: The MAF was used in those parts of the clinical procedures when high resolution and image quality was essential. The integral patient dose as represented by the KAP value was substantially lower when using the MAF than when using the FPD due to the much smaller volume of tissue irradiated. This research was supported in part by Toshiba Medical Systems Corporation and NIH Grant R01EB002873.

  9. SU-D-204-05: Quantitative Comparison of a High Resolution Micro-Angiographic Fluoroscopic (MAF) Detector with a Standard Flat Panel Detector (FPD) Using the New Metric of Generalized Measured Relative Object Detectability (GM-ROD)

    SciTech Connect

    Russ, M; Ionita, C; Bednarek, D; Rudin, S

    2015-06-15

    Purpose: In endovascular image-guided neuro-interventions, visualization of fine detail is paramount. For example, the ability of the interventionist to visualize the stent struts depends heavily on the x-ray imaging detector performance. Methods: A study to examine the relative performance of the high resolution MAF-CMOS (pixel size 75µm, Nyquist frequency 6.6 cycles/mm) and a standard Flat Panel Detector (pixel size 194µm, Nyquist frequency 2.5 cycles/mm) detectors in imaging a neuro stent was done using the Generalized Measured Relative Object Detectability (GM-ROD) metric. Low quantum noise images of a deployed stent were obtained by averaging 95 frames obtained by both detectors without changing other exposure or geometric parameters. The square of the Fourier transform of each image is taken and divided by the generalized normalized noise power spectrum to give an effective measured task-specific signal-to-noise ratio. This expression is then integrated from 0 to each of the detector’s Nyquist frequencies, and the GM-ROD value is determined by taking a ratio of the integrals for the MAF-CMOS to that of the FPD. The lower bound of integration can be varied to emphasize high frequencies in the detector comparisons. Results: The MAF-CMOS detector exhibits vastly superior performance over the FPD when integrating over all frequencies, yielding a GM-ROD value of 63.1. The lower bound of integration was stepped up in increments of 0.5 cycles/mm for higher frequency comparisons. As the lower bound increased, the GM-ROD value was augmented, reflecting the superior performance of the MAF-CMOS in the high frequency regime. Conclusion: GM-ROD is a versatile metric that can provide quantitative detector and task dependent comparisons that can be used as a basis for detector selection. Supported by NIH Grant: 2R01EB002873 and an equipment grant from Toshiba Medical Systems Corporation.

  10. Solar collector panels (process-method). Rainwater collection and storage

    SciTech Connect

    Mowery, J.W.

    1981-10-15

    A process for producing panels for solar heating of potable water is described. The panels have PVC tubing flat-coiled into square or rectangular shapes. Also described is a cistern for collecting and storing rainwater. (LEW)

  11. Advancing History Education in American Schools. A Symposium at the Library of Congress. Panel 3. Occasional Paper.

    ERIC Educational Resources Information Center

    National Council for History Education, Inc., Westlake, OH.

    This occasional paper discusses and examines the teaching of history in U.S. schools by noted historians. Byron Hollinshead, vice chair of the National Center for History Education, was moderator for the panel. William H. McNeill, University of Chicago, discussed the problem of pigeonholing or simplifying history into simple equations and how…

  12. Charlie Flats

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image from the Mars Exploration Rover Opportunity's panoramic camera shows a region of the rock outcrop at Meridiani Planum, Mars, dubbed 'Charlie Flats.' This region is a rich science target for Opportunity because it contains a diverse assortment of small grains, pebbles and spherules, as well as both dark and light soil deposits. The area seen here measures approximately 0.6 meters (2 feet) across. The smallest grains visible in this image are only a few millimeters in size. The approximate true color image was acquired on Sol 20 of Opportunity's mission with panoramic camera filters red, green and blue. [figure removed for brevity, see original site] Click on image for larger view Charlie Flats Spectra The chart above shows examples of spectra, or light wave patterns, extracted from the region of the Meridiani Planum rock outcrop dubbed 'Charlie Flats,' a rich science target for the Mars Exploration Rover Opportunity. The spectra were extracted from the similarly colored regions in the image on the left, taken by the rover's panoramic camera. The green circle identifies a bright, dust-like soil deposit. The red circle identifies a dark soil region. The yellow identifies a small, angular rock chip with a strong near-infrared band. The pink identifies a sphere-shaped pebble with a different strong near-infrared band. The cyan circle shows a dark, grayish pebble.

  13. Plate-fin panel heat exchanger and panel components thereof

    SciTech Connect

    Heronemus, W.E.

    1985-02-05

    A plate-fin panel for a heat exchanger may be either formed as an aluminum extrusion or fabricated from a corrugated metal sheet sandwiched between two flat metal sheets. The extruded aluminum version may be clad with protective sheet metal jackets made of, or coated with, a corrosion resistant Cu-Ni alloy. Individual panel sections can be joined together by tongue and groove engagement to obtain a total desired panel width if available extrusion press or rolling mill capacity is insufficient. The plate-fin panels are assembled into slotted headering plates, and a layer of synthetic plastics potting compound seals dissimilar metal joints against electrolytic corrosion as well as leakage and provides sufficient adhesive strength to reduce or eliminate the need for welding the panels to the headers. Mechanical brush or hydraulic jet apparatus is capable of continuously or intermittently cleaning slime or encrustations from all panel surfaces exposed to seawater.

  14. Origami of thick panels

    NASA Astrophysics Data System (ADS)

    Chen, Yan; Peng, Rui; You, Zhong

    2015-07-01

    Origami patterns, including the rigid origami patterns in which flat inflexible sheets are joined by creases, are primarily created for zero-thickness sheets. In order to apply them to fold structures such as roofs, solar panels, and space mirrors, for which thickness cannot be disregarded, various methods have been suggested. However, they generally involve adding materials to or offsetting panels away from the idealized sheet without altering the kinematic model used to simulate folding. We develop a comprehensive kinematic synthesis for rigid origami of thick panels that differs from the existing kinematic model but is capable of reproducing motions identical to that of zero-thickness origami. The approach, proven to be effective for typical origami, can be readily applied to fold real engineering structures.

  15. Panel 5: Microbiology and Immunology Panel

    PubMed Central

    Murphy, Timothy F.; Chonmaitree, Tasnee; Barenkamp, Stephen; Kyd, Jennelle; Nokso-Koivisto, Johanna; Patel, Janak A.; Heikkinen, Terho; Yamanaka, Noboru; Ogra, Pearay; Swords, W. Edward; Sih, Tania; Pettigrew, Melinda M.

    2014-01-01

    Objective The objective is to perform a comprehensive review of the literature from January 2007 through June 2011 on the virology, bacteriology, and immunology related to otitis media. Data Sources PubMed database of the National Library of Medicine. Review Methods Three subpanels with co-chairs comprising experts in the virology, bacteriology, and immunology of otitis media were formed. Each of the panels reviewed the literature in their respective fields and wrote draft reviews. The reviews were shared with all panel members, and a second draft was created. The entire panel met at the 10th International Symposium on Recent Advances in Otitis Media in June 2011 and discussed the review and refined the content further. A final draft was created, circulated, and approved by the panel. Conclusion Excellent progress has been made in the past 4 years in advancing an understanding of the microbiology and immunology of otitis media. Advances include laboratory-based basic studies, cell-based assays, work in animal models, and clinical studies. Implications for Practice The advances of the past 4 years formed the basis of a series of short-term and long-term research goals in an effort to guide the field. Accomplishing these goals will provide opportunities for the development of novel interventions, including new ways to better treat and prevent otitis media. PMID:23536533

  16. Design procedures for flutter-free surface panels

    NASA Technical Reports Server (NTRS)

    Laurenson, R. M.; Mcpherson, J. I.

    1977-01-01

    An approach for the design of lightweight external surface panel configurations to preclude panel flutter was developed. Design procedures were developed for flat orthotropic panels under the interacting influence of parameters such as support flexibility, inplane loads, pressure differential, and flow angularity. The basic relationships required to define these design procedures were based on theoretical panel flutter analyses. Where possible, the design procedures were verified through comparison with available experimental panel flutter data.

  17. Managing the risks of extreme events and disasters to advance climate change adaptation. Special report of the Intergovernmental Panel on Climate Change (IPCC)

    SciTech Connect

    Field, C.B.; Barros, V.; Stocker, T.F.

    2012-07-01

    This Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX) has been jointly coordinated by Working Groups I (WGI) and II (WGII) of the Intergovernmental Panel on Climate Change (IPCC). The report focuses on the relationship between climate change and extreme weather and climate events, the impacts of such events, and the strategies to manage the associated risks. This Special Report, in particular, contributes to frame the challenge of dealing with extreme weather and climate events as an issue in decision making under uncertainty, analyzing response in the context of risk management. The report consists of nine chapters, covering risk management; observed and projected changes in extreme weather and climate events; exposure and vulnerability to as well as losses resulting from such events; adaptation options from the local to the international scale; the role of sustainable development in modulating risks; and insights from specific case studies. (LN)

  18. 20-kW solar photovoltaic flat-panel power system for an uninterruptible power-system load in El Paso, Texas. Phase II. System fabrication. Final report October 1, 1979-May 31, 1981

    SciTech Connect

    Risser, V.V.

    1981-12-01

    The system plans, construction, integration and test, and performance evaluation are discussed for the photovoltaic power supply at the Newman Power Station in El Paso, Texas. The system consists of 64 parallel-connected panels, each panel containing nine series-connected photovoltaic modules. The system is connected, through power monitoring equipment, to an existing DC bus that supplies uninterruptible power to a computer that controls the power generating equipment. The site is described and possible environmental hazards are assessed. Site preparation and the installation of the photovoltaic panels, electrical cabling, and instrumentation subsystems are described. System testing includes initial system checkout, module performance test, control system test. A training program for operators and maintenance personnel is briefly described, including visual aids. Performance data collection and analysis are described, and actual data are compared with a computer simulation. System drawings are included. (LEW)

  19. Advancing History Education in American Schools. A Symposium at the Library of Congress. Panel 1. Occasional Paper.

    ERIC Educational Resources Information Center

    National Council for History Education, Inc., Westlake, OH.

    This occasional paper discusses and advances the teaching of history in U.S. schools by noted historians. James Billington, the Librarian of Congress, explains the resources available through the Library of Congress' National Digital Library Program designed to bring five million items into digitized format and make them available throughout the…

  20. The effect of oblique angle of sound incidence, realistic edge conditions, curvature and in-plane panel stresses on the noise reduction characteristics of general aviation type panels

    NASA Technical Reports Server (NTRS)

    Grosveld, F.; Lameris, J.; Dunn, D.

    1979-01-01

    Experiments and a theoretical analysis were conducted to predict the noise reduction of inclined and curved panels. These predictions are compared to the experimental results with reasonable agreement between theory and experiment for panels under an oblique angle of sound incidence. Theoretical as well as experimental results indicate a big increase in noise reduction when a flat test panel is curved. Further curving the panel slightly decreases the noise reduction. Riveted flat panels are shown to give a higher noise reduction in the stiffness-controlled frequency region, while bonded panels are superior in this region when the test panel is curved. Experimentally measured noise reduction characteristics of flat aluminum panels with uniaxial in-plane stresses are presented and discussed. These test results indicate an important improvement in the noise reduction of these panels in the frequency range below the fundamental panel/cavity frequency.

  1. JTEC panel on display technologies in Japan

    NASA Technical Reports Server (NTRS)

    Tannas, Lawrence E., Jr.; Glenn, William E.; Credelle, Thomas; Doane, J. William; Firester, Arthur H.; Thompson, Malcolm

    1992-01-01

    This report is one in a series of reports that describes research and development efforts in Japan in the area of display technologies. The following are included in this report: flat panel displays (technical findings, liquid crystal display development and production, large flat panel displays (FPD's), electroluminescent displays and plasma panels, infrastructure in Japan's FPD industry, market and projected sales, and new a-Si active matrix liquid crystal display (AMLCD) factory); materials for flat panel displays (liquid crystal materials, and light-emissive display materials); manufacturing and infrastructure of active matrix liquid crystal displays (manufacturing logistics and equipment); passive matrix liquid crystal displays (LCD basics, twisted nematics LCD's, supertwisted nematic LCD's, ferroelectric LCD's, and a comparison of passive matrix LCD technology); active matrix technology (basic active matrix technology, investment environment, amorphous silicon, polysilicon, and commercial products and prototypes); and projection displays (comparison of Japanese and U.S. display research, and technical evaluation of work).

  2. Panel flutter

    NASA Technical Reports Server (NTRS)

    Dowell, E. H.

    1972-01-01

    Criteria are presented for the prediction of panel flutter, determination of its occurrence, design for its prevention, and evaluation of its severity. Theoretical analyses recommended for the prediction of flutter stability boundaries, vibration amplitudes, and frequencies for several types of panels are described. Vibration tests and wind tunnel tests are recommended for certain panels and environmental flow conditions to provide information for design of verification analysis. Appropriate design margins on flutter stability boundaries are given and general criteria are presented for evaluating the severity of possible short-duration, limited-amplitude panel flutter on nonreusable vehicles.

  3. Collation of quarterly reports on air flat plate collectors

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The solar 2 air flat plate collectors are described. The development and fabrication of a prototype air flat plate collector subsystem containing 320 square feet of collector area are described. Three instrumented panels were completely assembled with glazing and insulation. Manufacture of the last seven prototype collectors was completed in October 1977.

  4. The Panel Discussion.

    ERIC Educational Resources Information Center

    Journal of Chemical Education, 1980

    1980-01-01

    Summarizes the views of panel members at a symposium on the place of inorganic chemistry in the undergraduate curriculum. Suggests one semester of intermediate inorganic chemistry, followed by a year of physical chemistry and a semester of advanced inorganic chemistry as a reasonable prescription for the modern undergraduate curriculum. (Author/JN)

  5. A review of the Victoria, Australia granny flat program.

    PubMed

    Lazarowich, N M

    1990-04-01

    The 10-year-old Victoria, Australia granny flat program has about 3000 units in place. Granny flats, designed as standardized units using panels, offer privacy yet proximity to family members. There are suggestions they be considered as affordable housing for younger people. This review of the Victoria program suggests that state initiatives are more successful than local ones, and that decentralized administration is associated with increased ability to delivery the granny flat units.

  6. Panel methods

    NASA Astrophysics Data System (ADS)

    Srivastava, Ashok

    1993-10-01

    A comprehensive description of panel methods has been given to enable an understanding of the underlying theory and the basic structure of the panel codes for aerodynamic applications. Panel methods have seen peak activity in the industry and remain as yet the sole technique for efficient and practical computations on complex-aircraft configurations. The method of the linearized approach of solving flow problems is well proven and till the turn of the century panel methods will continue to remain as the workhorse for computing aerodynamic characteristics of aircraft shapes in the industry. The alternative Euler and Navier-Stokes solvers have yet to mature for applications to complex shapes, hence panel methods will be in the light for at least another decade.

  7. Panel 3 - characterization

    SciTech Connect

    Erck, R.A.; Erdemir, A.; Janghsing Hsieh; Lee, R.H.; Xian Zheng Pan; Deming Shu; Feldman, A.; Glass, J.T.; Kleimer, R.; Lawton, E.A.

    1993-01-01

    The task of this panel was to identify and prioritize needs in the area of characterization of diamond and diamond-like-carbon (DLC) films for use in the transportation industry. Until recent advances in production of inexpensive films of diamonds and DLC, it was not feasible that these materials could be mass produced. The Characterization Panel is restricting itself to identifying needs in areas that would be most useful to manufacturers and users in producing and utilizing diamond and DLC coatings in industry. These characterization needs include in-situ monitoring during growth, relation of structure to performance, and standards and definitions.

  8. PREDICTING CIRRHOSIS AND CLINICAL OUTCOMES IN PATIENTS WITH ADVANCED CHRONIC HEPATITIS C WITH A PANEL OF GENETIC MARKERS (CRS7)

    PubMed Central

    Curto, Teresa M.; Lagier, Robert J.; Lok, Anna S.; Everhart, James E.; Rowland, Charles M.; Sninsky, John J.

    2011-01-01

    Objectives Genetic factors may play a role in fibrosis progression in patients with chronic hepatitis C (CHC). A cirrhosis risk score (CRS7) with 7 SNPs was previously shown to correlate with cirrhosis in patients with CHC. This study aimed to assess the validity of CRS7 as a marker of fibrosis progression and cirrhosis and as a predictor of clinical outcomes in patients with CHC. Methods A total of 938 patients (677 Caucasians, 165 African Americans, and 96 Hispanic/Other) in the HALT-C Trial were studied. CRS7 was categorized a priori as high risk (n=440), medium risk (n=310) or low risk (n=188). Patients were assessed for four possible outcomes: fibrosis progression, cirrhosis, clinical outcomes (decompensation or hepatocellular carcinoma [HCC]), or HCC alone. Results 29% (142/493) developed an increase in fibrosis score by ≥ 2 points on follow-up biopsies, 58% had cirrhosis on one or more biopsies, 35% developed at least one clinical outcome, and 13% developed HCC. CRS7 (trend test) was associated with risk for fibrosis progression (p=0.04) with adjusted hazard ratio (HR) of 1.27 (95%CI: 1.01–1.58) and with cirrhosis (p=0.05) with adjusted odds ratio (OR) of 1.19 (1.00–1.41). Rates of HCC and clinical outcomes were increased in patients with higher CRS7 scores, but were not statistically significant (p=0.12 clinical outcomes, and p=0.07 HCC). A SNP in AZIN1 was significantly associated with fibrosis progression. Conclusions CRS7 was validated as a predictor of fibrosis progression and cirrhosis among HALT-C patients, who all had advanced fibrosis. CRS7 was not predictive of clinical outcome. PMID:21946897

  9. Solar panel

    SciTech Connect

    Bayles, B.R.

    1981-09-29

    A solar panel includes a base within which are mounted transversely extending conduits. A heat collector plate in the base is in heat conductive relationship with the conduits for the heating of a fluid medium. The base additionally supports a transparent cover outwardly spaced from the heat collector plate to provide a protective insulative air space over the plate. A manifold communicates one series of panels with those of an adjacent series. A modified base dispenses with a collector plate and is formed so as to define integral lengthwise extending passageways for the solar heated medium. Inserted nipples interconnect the passageways of adjacent panels.

  10. Liver Panel

    MedlinePlus

    ... AACC products and services. Advertising & Sponsorship: Policy | Opportunities Liver Panel Share this page: Was this page helpful? Also known as: Liver Profile; Liver Function Tests; LFTs Formal name: Hepatic ...

  11. 100-Kilowatt solar photovoltaic flat-panel power system for the combined Beverly High School/C. H. Patten Vocational High School, Beverly, Massachusetts. Phase III. System operation and evaluation

    SciTech Connect

    Addiss, R.R. Jr.

    1985-06-01

    This report describes the first year's operation of a 100-kW photovoltaic flat-plate system at Beverly High School, Beverly, Massachusetts. Also included in the report are separate first-year reports by Stone and Webster, New England Electric System, and the Beverly Public School System. Over the reporting period, the systems produced nearly 90,000 kWh of electricity valued at nearly $5000 at an average buy-back rate from the utility of 5.78 cents/kWh. The cost of operation and maintenance during this first year was excessive, nearly equal to the total value derived from the energy. The system reliability problems have been addressed, and the operation and maintenance for the next year is expected to be about 10% of the energy value.

  12. Stigmatic flat focal field spectrograph

    NASA Astrophysics Data System (ADS)

    Niemczyk, T. M.; Gobeli, G. W.

    Advances in two dimensional detectors have created a need for a spectrograph that can produce high fidelity images. Aberrations that detract from image quality in conventional spectrographs are discussed. Ray trace and experimental results obtained for a unique spectrograph designed for use with array detectors, i.e., designed to produce high fidelity images, are presented. The spectrograph employs toroidal mirrors to achieve stigmatic imaging in a flat focal field.

  13. Experimental comparison between several photovoltaic panels, regarding the solar energy collection

    SciTech Connect

    Lorenzo, E.; Laspiur, A.; Molledo, A.G.; Romero, S.L.

    1984-05-01

    This paper summarizes the results of an experiment carried out at the Instituto de Energia Solar of the Universidad Politecnica de Madrid, whose main objective is the analysis of the energy collected by different kinds of photovoltaic panels. Special interest is paid to the study of bifacial flat panels and static concentrators using bifacial solar cells. Using the annual energy collected by a conventional static-monofacial flat panel as a basis for comparison, results show that static bifacial flat panels collect 60% more. The use of a two-axis tracking causes an increase of 40% and the combination of a bifacial flat panel with a two-axes tracking causes an increase of 80%. Finally, it is shown that the performance of static concentrators and monofacial flat panels is very similar.

  14. Development of tailorable advanced blanket insulation for advanced space transportation systems

    NASA Technical Reports Server (NTRS)

    Calamito, Dominic P.

    1987-01-01

    Two items of Tailorable Advanced Blanket Insulation (TABI) for Advanced Space Transportation Systems were produced. The first consisted of flat panels made from integrally woven, 3-D fluted core having parallel fabric faces and connecting ribs of Nicalon silicon carbide yarns. The triangular cross section of the flutes were filled with mandrels of processed Q-Fiber Felt. Forty panels were prepared with only minimal problems, mostly resulting from the unavailability of insulation with the proper density. Rigidizing the fluted fabric prior to inserting the insulation reduced the production time. The procedures for producing the fabric, insulation mandrels, and TABI panels are described. The second item was an effort to determine the feasibility of producing contoured TABI shapes from gores cut from flat, insulated fluted core panels. Two gores of integrally woven fluted core and single ply fabric (ICAS) were insulated and joined into a large spherical shape employing a tadpole insulator at the mating edges. The fluted core segment of each ICAS consisted of an Astroquartz face fabric and Nicalon face and rib fabrics, while the single ply fabric segment was Nicalon. Further development will be required. The success of fabricating this assembly indicates that this concept may be feasible for certain types of space insulation requirements. The procedures developed for weaving the ICAS, joining the gores, and coating certain areas of the fabrics are presented.

  15. 29. INTERIOR VIEW TO THE NORTHEAST OF CONTROL PANEL AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    29. INTERIOR VIEW TO THE NORTHEAST OF CONTROL PANEL AND VIEWING WINDOW IN ROOM 105, THE CONTROL ROOM. - Nevada Test Site, Pluto Facility, Disassembly Building, Area 26, Wahmonie Flats, Cane Spring Road, Mercury, Nye County, NV

  16. Transverse flat plate heat pipe experiment

    NASA Technical Reports Server (NTRS)

    Edelstein, F.

    1978-01-01

    This paper describes a Shuttle-launched flight experiment to evaluate the performance of a transverse flat plate heat pipe that serves as an integral temperature control/mounting panel for electronic equipment. A transverse heat pipe is a gas-controlled variable conductance heat pipe that can handle relatively large thermal loads. An experiment designed to flight test the concept over a 6-9 month period is self-sufficient with respect to electrical power, timing sequences, and data storage.

  17. Panel Sessions.

    ERIC Educational Resources Information Center

    Proceedings of the ASIS Mid-Year Meeting, 1992

    1992-01-01

    Lists the speakers and summarizes the issues addressed for 12 panel sessions on topics related to networking, including libraries and national networks, federal national resources and energy programs, multimedia issues, telecommuting, remote image serving, accessing the Internet, library automation, scientific information, applications of Z39.50,…

  18. Media Panel.

    ERIC Educational Resources Information Center

    Marklund, Inger, Ed.; Hanse, Mona-Britt, Ed.

    1984-01-01

    The Swedish Media Panel is a research program about children and young persons and their use of mass media. The aim of the ten-year (1975-1985) project is to explain how media habits originate, how they change as children grow older, what factors on the part of children themselves and in their surroundings may be connected with a certain use of…

  19. Higher-Order Panel Method for Aerodynamic Flow Analysis

    NASA Technical Reports Server (NTRS)

    Erickson, L.; Carmichael, R. L.; Levin, A. D.; Magnus, A.; Epton, M.; Baruah, P.; Massena, B.; Bussoletti, J.; Sidwell, K.; Johnson, F.; Zeppa, J.; Bates, G.; Clemens, D.; Derbyshire, T.; Purdon, D.; Chiang, D.; Rubbert, P.; Nelson, F.; Wai, J.; Tsurusaki, K.; Smith, N.; Snyder, J. R.; Sotomayer, W.; Dejongh, J.; Thomas, J. L.

    1982-01-01

    PANAIR uses high-order panel method to predict inviscid subsonic or supersonic flows about arbitrary configuration. Panel method solves linear partial differential equation numerically by approximating configuration surface with panels on which unknown "singularity strengths" are defined. PANAIR includes advanced software technology as well as advanced aerodynamic technology.

  20. 61. Upper panel in cornerpower panel lcpa lower panel in ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    61. Upper panel in corner-power panel lcpa lower panel in corner-oxygen regeneration unit, at right-air conditioner control panel, on floor-bio-pack 45 for emergency breathing, looking northwest - Ellsworth Air Force Base, Delta Flight, Launch Control Facility, County Road CS23A, North of Exit 127, Interior, Jackson County, SD

  1. Normal pressure tests on unstiffened flat plates

    NASA Technical Reports Server (NTRS)

    Head, Richard M; Sechler, Ernest J

    1944-01-01

    Flat sheet panels of aluminum alloy (all 17S-T except for two specimens of 24S-T) were tested under normal pressures with clamped edge supports in the structures laboratory of the Guggenheim Aeronautical Laboratory, California Institute of Technology. The thicknesses used ranged from 0.010 to 0.080 inch; the panel sizes ranged from 10 by 10 inches to 10 by 40 inches; and the pressure range was from 0 to 60-pounds-per-square-inch gage. Deflection patterns were measured and maximum tensile strains in the center of the panel were determined by electric strain gages. The experimental data are presented by pressure-strain, pressure-maximum-deflection, and pressure-deflection curves. The results of these tests have been compared with the corresponding strains and deflections as calculated by the simple membrane theory and by large deflection theories.

  2. Architectural Panels

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Alliance Wall Corporation's Whyteboard, a porcelain enamel on steel panels wall board, owes its color stability to a KIAC engineering background study to identify potential technologies and manufacturers of equipment which could be used to detect surface flaws. One result of the data base search was the purchase of a spectrocolorimeter which enables the company to control some 250 standard colors, and match special colors.

  3. 16. VIEW OF THE STATIONARY OPERATING ENGINEER CONTROL PANEL INSTALLATION. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. VIEW OF THE STATIONARY OPERATING ENGINEER CONTROL PANEL INSTALLATION. THE PANEL CONTROLS AIR-HANDLING EQUIPMENT AND AIR PRESSURE WITHIN THE BUILDING. (10/6/69) - Rocky Flats Plant, Plutonium Manufacturing Facility, North-central section of Plant, just south of Building 776/777, Golden, Jefferson County, CO

  4. 2. VIEW OF THE EXPERIMENT CONTROL PANEL IN 1970. THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. VIEW OF THE EXPERIMENT CONTROL PANEL IN 1970. THE NUCLEAR SAFETY GROUP CONDUCTED ABOUT 1,700 CRITICAL MASS EXPERIMENTS USING URANIUM AND PLUTONIUM IN SOLUTIONS (900 TESTS), COMPACTED POWDER (300), AND METALLIC FORMS (500). ALL 1,700 CRITICALITY ASSEMBLIES WERE CONTROLLED FROM THIS PANEL. - Rocky Flats Plant, Critical Mass Laboratory, Intersection of Central Avenue & 86 Drive, Golden, Jefferson County, CO

  5. Foil Panel Mirrors for Nonimaging Applications

    NASA Technical Reports Server (NTRS)

    Kuyper, D. J.; Castillo, A. A.

    1984-01-01

    Large durable, lightweight mirrors made by bonding thick aluminum foil to honeycomb panels or other rigid, flat backings. Mirrors suitable for use as infrared shields, telescope doors, solar-furnance doors, advertising displays, or other reflectors that require low thermal emissivity and high specularity but do not require precise surface figure necessary for imaging.

  6. Multiple-Panel Cylindrical Solar Concentrator

    NASA Technical Reports Server (NTRS)

    Brown, E. M.

    1983-01-01

    Trough composed of many panels concentrates Sun's energy on solar cells, even when trough is not pointed directly at Sun. Tolerates deviation as great as 5 degrees from direction of sun. For terrestrial applications, multiple-flat-plate design offers potential cost reduction and ease of fabrication.

  7. Recent advances in flexible low power cholesteric LCDs

    NASA Astrophysics Data System (ADS)

    Khan, Asad; Shiyanovskaya, Irina; Montbach, Erica; Schneider, Tod; Nicholson, Forrest; Miller, Nick; Marhefka, Duane; Ernst, Todd; Doane, J. W.

    2006-05-01

    Bistable reflective cholesteric displays are a liquid crystal display technology developed to fill a market need for very low power displays. Their unique look, high reflectivity, bistability, and simple structure make them an ideal flat panel display choice for handheld or other portable devices where small lightweight batteries with long lifetimes are important. Applications ranging from low resolution large signs to ultra high resolution electronic books can utilize cholesteric displays to not only benefit from the numerous features, but also create enabling features that other flat panel display technologies cannot. Flexible displays are the focus of attention of numerous research groups and corporations worldwide. Cholesteric displays have been demonstrated to be highly amenable to flexible substrates. This paper will review recent advances in flexible cholesteric displays including both phase separation and emulsification approaches to encapsulation. Both approaches provide unique benefits to various aspects of manufacturability, processes, flexibility, and conformability.

  8. Flat Pack Toy Design

    ERIC Educational Resources Information Center

    Hutcheson, Brian

    2007-01-01

    In this article, the author introduces the concept of flat pack toys. Flat pack toys are designed using a template on a single sheet of letter-sized card stock paper. Before being cut out and built into a three-dimensional toy, they are scanned into the computer and uploaded to a website. With the template accessible from the website, anyone with…

  9. Flat feet in children.

    PubMed

    Barry, R J; Scranton, P E

    1983-12-01

    In the assessment of the child with flat feet a sound knowledge of arch and subtalar biomechanics, epidemiology, and etiology is important. The occurrence and natural history of flat feet are presented, and treatment modalities that have withstood the test of time are discussed.

  10. What really causes flat slab subduction?

    NASA Astrophysics Data System (ADS)

    Manea, V. C.; Perez-Gussinye, M.; Manea, M.

    2014-12-01

    How flat slab geometries are generated has been long debated. It has been suggested thattrenchward motion of thick cratons in some areas of South America and Cenozoic NorthAmerica progressively closed the asthenospheric wedge and induced flat subduction. Here wedevelop time-dependent numerical experiments to explore how trenchward motion of thickcratons may result in flat subduction. We find that as the craton approaches the trench andthe wedge closes, two opposite phenomena control slab geometry: the suction between oceanand continent increases, favoring slab flattening, while the mantle confined within the closingwedge dynamically pushes the slab backward and steepens it. When the slab retreats, as inthe Peru and Chile flat slabs, the wedge closure rate and dynamic push are small and suctionforces generate, in some cases, flat subduction. We model the past 30 m.y. of subduction in theChilean flat slab area and demonstrate that trenchward motion of thick lithosphere, 200-300km, currently ~700-800 km away from the Peru-Chile Trench, reproduces a slab geometrythat fits the stress pattern, seismicity distribution, and temporal and spatial evolution ofdeformation and volcanism in the region. We also suggest that varying trench kinematics mayexplain some differing slab geometries along South America. When the trench is stationaryor advances, the mantle flow within the closing wedge strongly pushes the slab backward andsteepens it, possibly explaining the absence of flat subduction in the Bolivian orocline.

  11. Exascale Workshop Panel Report Meeting

    SciTech Connect

    Khaleel, Mohammad A.

    2010-07-01

    The Exascale Review Panel consists of 12 scientists and engineers with experience in various aspects of high-performance computing and its application, development, and management. The Panel hear presentations by several representatives of the workshops and town meetings convened over the past few years to examine the need for exascale computation capability and the justification for a U.S. Department of Energy (DOE) program to develop such capability. This report summarizes information provided by the presenters and substantial written reports to the Panel in advance of the meeting in Washington D.C. on January 19-20, 2010. The report also summarizes the Panel's conclusions with regard to the justification of a DOE-led exascale initiative.

  12. Advanced night vision goggles

    NASA Astrophysics Data System (ADS)

    Thacker, Clinton

    2003-02-01

    The Advanced Night Vision Goggle (ANVG) program is developing integrated wide field of view (WFOV) helmet-mounted image intensifier night vision goggle systems. ANVG will provide a FOV of approximately 40° (vertical) × 100° (horizontal) and an integrated heads-up display for overlay of flight symbology and/or FLIR imagery. The added FLIR complements the I2 imagery in out of the window or ground applications. ANVG will significantly improve safety, situational awareness, and mission capabilities in differing environments. ANVG achieves the ultra wide FOV using four image intensifier tubes in a head-mounted configuration. Additional features include a miniature flat panel display and a lightweight uncooled FLIR. The integrated design will demonstrate the capability of helmet-mounted I2 and FLIR image fusion. Fusion will be accomplished optically and will offer significant opportunities for ground applications. This paper summarizes the basic technologies, lessons learned, and program status.

  13. Lightweight composites for modular panelized construction

    NASA Astrophysics Data System (ADS)

    Vaidya, Amol S.

    Rapid advances in construction materials technology have enabled civil engineers to achieve impressive gains in the safety, economy, and functionality of structures built to serve the common needs of society. Modular building systems is a fast-growing modern, form of construction gaining recognition for its increased efficiency and ability to apply modern technology to the needs of the market place. In the modular construction technique, a single structural panel can perform a number of functions such as providing thermal insulation, vibration damping, and structural strength. These multifunctional panels can be prefabricated in a manufacturing facility and then transferred to the construction site. A system that uses prefabricated panels for construction is called a "panelized construction system". This study focuses on the development of pre-cast, lightweight, multifunctional sandwich composite panels to be used for panelized construction. Two thermoplastic composite panels are proposed in this study, namely Composite Structural Insulated Panels (CSIPs) for exterior walls, floors and roofs, and Open Core Sandwich composite for multifunctional interior walls of a structure. Special manufacturing techniques are developed for manufacturing these panels. The structural behavior of these panels is analyzed based on various building design codes. Detailed descriptions of the design, cost analysis, manufacturing, finite element modeling and structural testing of these proposed panels are included in this study in the of form five peer-reviewed journal articles. The structural testing of the proposed panels involved in this study included flexural testing, axial compression testing, and low and high velocity impact testing. Based on the current study, the proposed CSIP wall and floor panels were found satisfactory, based on building design codes ASCE-7-05 and ACI-318-05. Joining techniques are proposed in this study for connecting the precast panels on the construction

  14. An Ultra-Deep Targeted Sequencing Gene Panel Improves the Prognostic Stratification of Patients With Advanced Oral Cavity Squamous Cell Carcinoma.

    PubMed

    Liao, Chun-Ta; Chen, Shu-Jen; Lee, Li-Yu; Hsueh, Chuen; Yang, Lan-Yan; Lin, Chien-Yu; Fan, Kang-Hsing; Wang, Hung-Ming; Ng, Shu-Hang; Lin, Chih-Hung; Tsao, Chung-Kan; Chen, I-How; Chang, Kai-Ping; Huang, Shiang-Fu; Kang, Chung-Jan; Chen, Hua-Chien; Yen, Tzu-Chen

    2016-02-01

    An improved prognostic stratification of patients with oral cavity squamous cell carcinoma (OSCC) and pathologically positive (pN+) nodes is urgently needed. Here, we sought to examine whether an ultra-deep targeted sequencing (UDT-Seq) gene panel may improve the prognostic stratification in this patient group.A mutation-based signature affecting 10 genes (including genetic mutations in 6 oncogenes and 4 tumor suppressor genes) was devised to predict disease-free survival (DFS) in 345 primary tumor specimens obtained from pN+ OSCC patients. Of the 345 patients, 144 were extracapsular spread (ECS)-negative and 201 were ECS-positive. The 5-year locoregional control, distant metastases, disease-free, disease-specific, and overall survival (OS) rates served as outcome measures.The UDT-Seq panel was an independent risk factor (RF) for 5-year locoregional control (P = 0.0067), distant metastases (P = 0.0001), DFS (P < 0.0001), disease-specific survival (DSS, P < 0.0001), and OS (P = 0.0003) in pN+ OSCC patients. The presence of ECS and pT3-4 disease were also independent RFs for DFS, DSS, and OS. A prognostic scoring system was formulated by summing up the significant covariates (UDT-Seq, ECS, pT3-4) separately for each survival endpoint. The presence of a positive UDT-Seq panel (n = 77) significantly improved risk stratification for all the survival endpoints as compared with traditional AJCC staging (P < 0.0001). Among ECS-negative patients, those with a UDT-Seq-positive panel (n = 31) had significantly worse DFS (P = 0.0005) and DSS (P = 0.0002). Among ECS-positive patients, those with a UDT-Seq-positive panel (n = 46) also had significantly worse DFS (P = 0.0032) and DSS (P = 0.0098).Our UDT-Seq gene panel consisting of clinically actionable genes was significantly associated with patient outcomes and provided better prognostic stratification than traditional AJCC staging. It was also able to predict prognosis in

  15. Advances in neutron radiographic techniques and applications: a method for nondestructive testing.

    PubMed

    Berger, Harold

    2004-10-01

    A brief history of neutron radiography is presented to set the stage for a discussion of significant neutron radiographic developments and an assessment of future directions for neutron radiography. Specific advances are seen in the use of modern, high dynamic range imaging methods (image plates and flat panels) and for high contrast techniques such as phase contrast, and phase-sensitive imaging. Competition for neutron radiographic inspection may develop as these techniques offer application prospects for X-ray methods.

  16. Flat-spectrum speech.

    PubMed

    Schroeder, M R; Strube, H W

    1986-05-01

    Flat-spectrum stimuli, consisting of many equal-amplitude harmonics, produce timbre sensations that can depend strongly on the phase angles of the individual harmonics. For fundamental frequencies in the human pitch range, many realizable timbres have vowel-like perceptual qualities. This observation suggests the possibility of constructing intelligible voiced speech signals that have flat-amplitude spectra. This paper describes a successful experiment of creating several different diphthongs by judicious choice of the phase angles of a flat-spectrum waveform. A possible explanation of the observed vowel timbres lies in the dependence of the short-time amplitude spectra on phase changes.

  17. Heat exchanger panel

    NASA Technical Reports Server (NTRS)

    Warburton, Robert E. (Inventor); Cuva, William J. (Inventor)

    2005-01-01

    The present invention relates to a heat exchanger panel which has broad utility in high temperature environments. The heat exchanger panel has a first panel, a second panel, and at least one fluid containment device positioned intermediate the first and second panels. At least one of the first panel and the second panel have at least one feature on an interior surface to accommodate the at least one fluid containment device. In a preferred embodiment, each of the first and second panels is formed from a high conductivity, high temperature composite material. Also, in a preferred embodiment, the first and second panels are joined together by one or more composite fasteners.

  18. Flat-plate /vapor-chamber/ heat pipes

    NASA Technical Reports Server (NTRS)

    Fleischman, G. L.; Marcus, B. D.; Mcintosh, R.; Ollendorf, S.

    1975-01-01

    This paper discusses the design, fabrication and testing of heat pipes constructed in the form of flat-plate panels. The test panels were constructed of copper with methyl alcohol as the working fluid. Capillary grooves etched on the internal surfaces provided evaporation and condensation heat-transfer coefficients on the order of 1600 Btu/hr-sq ft-deg F. Two panels were launched on board a sounding rocket; the payload reached an altitude of 140 miles, and zero gravity was achieved for almost six minutes. The panel with working fluid inside demonstrated a heat input flux of 2.5 watts/sq cm, with only a 3 to 5 C temperature difference throughout the entire panel.

  19. Flat plate solar oven

    SciTech Connect

    Parikh, M.

    1981-01-01

    The construction of an Indian Rs. 186 (US $20.33) flat-plate solar oven is described. Detailed drawings are provided and relevant information on cooking times and temperature for different foods is given.

  20. Flat-space singletons

    SciTech Connect

    Fronsdal, C.

    1987-02-15

    Singletons exist, as particles and as local fields, only in 3+2 de Sitter space. Their kinematical properties make them natural candidates for constituents of massless fields, and perhaps for quarks. It is interesting to find out how to describe this type of compositeness in flat space. A theory of interacting singleton fields in de Sitter space is now available, and in this paper we study the flat-space limit of the Green's functions of that theory. The flat-space limit is an autonomous theory of Green's functions, but is not an operator field theory. The three-point function is calculated and its flat-space limit is found to reveal glimpses of a physical interpretation. Causal and spectral properties are in accord with the tenets of axiomatic field theory. The theory is a generalization of local field theory, in which photons appear as composite objects although the physical S matrix is the same as in conventional QED.

  1. Concentrating Solar Panels: Bringing the Highest Power and Lowest Cost to the Rooftop

    SciTech Connect

    Michael Deck; Rick Russell

    2010-01-05

    Soliant Energy is a venture-capital-backed startup focused on bringing advanced concentrating solar panels to market. Our fundamental innovation is that we are the first company to develop a racking solar concentrator specifically for commercial rooftop applications, resulting in the lowest LCOE for rooftop electricity generation. Today, the commercial rooftop segment is the largest and fastest-growing market in the solar industry. Our concentrating panels can make a major contribution to the SAI's objectives: reducing the cost of solar electricity and rapidly deploying capacity. Our commercialization focus was re-shaped in 2009, shifting from an emphasis solely on panel efficiency to LCOE. Since the inception of the SAI program, LCOE has become the de facto standard for comparing commercial photovoltaic systems. While estimation and prediction models still differ, the emergence of performance-based incentive (PBI) and feed-in tariff (FIT) systems, as well as power purchase agreement (PPA) financing structures make LCOE the natural metric for photovoltaic systems. Soliant Energy has designed and demonstrated lower-cost, higher-power solar panels that consists of 6 (500X) PV module assemblies utilizing multi-junction cells and an integrated two-axis tracker. In addition, we have designed and demonstrated a prototype 1000X panel assembly with 8. Cost reductions relative to conventional flat panel PV systems were realized by (1) reducing the amount of costly semiconductor material and (2) developing strategies and processes to reduce the manufacturing costs of the entire system. Performance gains against conventional benchmarks were realized with (1) two-axis tracking and (2) higher-efficiency multi-junction PV cells capable of operating at a solar concentration ratio of 1000X (1000 kW/m2). The program objectives are: (1) Develop a tracking/concentrating solar module that has the same geometric form factor as a conventional flat, roof mounted photovoltaic (PV) panel

  2. Flat-panel imaging system for fluoroscopy applications

    NASA Astrophysics Data System (ADS)

    Colbeth, Richard E.; Allen, Maxwell J.; Day, Derek J.; Gilblom, David L.; Harris, Richard A.; Job, Isaias D.; Klausmeier-Brown, Martin E.; Pavkovich, John M.; Seppi, Edward J.; Shapiro, Edward G.; Wright, Michael D.; Yu, Jiann M.

    1998-07-01

    This paper describes a multi-mode, digital imager for real- time x-ray applications. The imager has three modes of operation: low dose fluoroscopy, zoom fluoroscopy, and high resolution radiography. These modes trade-off resolution or field-of-view for frame rate and additionally optimize the sensitivity of the imager to match the x-ray dose used in each mode. This large area sensing technology has a form factor similar to that of a film cassette, no geometric image distortion, no sensitivity to magnetic fields, a very large dynamic range which eliminates repeat shots due to over or under exposure, 12 bit digital output and the ability to switch between operating modes in real-time. The imager, which consists of three modules: the Receptor, the Power Supply and the Command Processor, is intended as a component in a larger imaging system. Preliminary characterization of the prototype imager in fluoroscopic mode at entrance exposure rates down to 2.5 (mu) R/frame, indicates that the DQE(f), MTF and low contrast resolution are comparable to that obtained with an image intensifier tube (IIT) coupled to a video camera.

  3. Tests of Flat Panels with Four Types of Stiffeners

    DTIC Science & Technology

    1943-01-01

    within one-half of 1 percent by a standard tensile test. in this test two Huggenberger tensometers with 1-inch gage lengths were used to measure the...into three equal parts by a lever arrsngement, the loads being 25-pound bags of shot. This lever system wss designed to fit all four stiffener spacings...the platens about an axis normal to the plane of the specimen was very small. In the second and third groups of tests, tensometers were also attached

  4. Optically Tiled Flat Panel Displays. A Feasibility Study

    DTIC Science & Technology

    1992-11-01

    distortion. The fabrication of a traditional rotational symmetric Fresnel lens could be possible using diamond turning methods. However the rotational...and allow the microlens array to be located next to the LCD module output polarizer and immediately followed by the negative Fresnel lens and then the...microlenses remapping the pixels onto a diffuser through a 4 negative Fresnel lens (Figure 11). This method could tile together LCD modules separated by a

  5. Development of Surfaces Optically Suitable for Flat Solar Panels

    NASA Technical Reports Server (NTRS)

    Desmet, D.; Jason, A.; Parr, A.

    1977-01-01

    Innovations in reflectometry techniques are described; and the development of an absorbing selective coating is discussed along with details of surface properties. Conclusions as to the parameterization desired for practical applications of selective surfaces are provided.

  6. Human Visual Performance and Flat Panel Display Image Quality

    DTIC Science & Technology

    1980-07-01

    lowest ranking indicates best performance) Color Meister and Sullivan (1969) Rizy (1967) Red Yellow Magenta White Cyan Blue Green 2 1 4...92940 Dr. Robert French Naval Ocean Systems San Diego, CA 92152 Dr. Ross L. Pepper Naval Ocean Systems Center Hawaii Laboratory P. 0. Box 997

  7. Fabric panel clean change-out frame

    DOEpatents

    Brown, Ronald M.

    1995-01-31

    A fabric panel clean change-out frame, for use on a containment structure having rigid walls, is formed of a compression frame and a closure panel. The frame is formed of elongated spacers, each carrying a plurality of closely spaced flat springs, and each having a hooked lip extending on the side of the spring facing the spacer. The closure panel is includes a perimeter frame formed of flexible, wedge-shaped frame members that are receivable under the springs to deflect the hooked lips. A groove on the flexible frame members engages the hooked lips and locks the frame members in place under the springs. A flexible fabric panel is connected to the flexible frame members and closes its center.

  8. Flat plate solar collector with a cantilevered mirror

    SciTech Connect

    Cohen, S.; Larson, D.C.

    1981-01-01

    The use of flat booster mirrors with flat plate collectors provides moderate solar flux concentration and enhanced performance especially when the mirrors are seasonally adjusted. Curved mirrors provide higher flux concentration and a practical system has been developed where the booster mirror is bent elastically. The system employs a single cantilever mirror which is located below a conventional flat plate collector. The mirror is clamped at the base of the collector panel and its free end is deflected upward; a smaller deflection is used in the fall and winter than in the spring and summer. The prototype system consists of a 0.9 by 2.5 m collector panel mounted on its side (horizontal fluid flow) and a 2.7 by 2.5 m elastic mirror. The mirror is made with aluminum sheet with an adherent aluminized acrylic film. The system has been designed for mounting on horizontal surfaces at latitudes of 10 to 50/sup 0/.

  9. Panel Discussion

    NASA Astrophysics Data System (ADS)

    Langer, James

    1997-03-01

    Panelists: Arthur Bienenstock, Stanford University Cherry Ann Murray, Lucent Technologies Venkatesh Narayanamurti, University of California-Santa Barbara Paul Peercy, SEMI-SEMATECH Robert Richardson, Cornell University James Roberto, Oak Ridge National Laboratory The Board on Physics and Astronomy is undertaking a series of reassessments of all branches of physics as the foundation of a new physics survey. As part of this project, a Committee on Condensed Matter and Materials Physics has been established under the leadership of Venkatesh Narayanamurti of the University of California-Santa Barbara. The committee has been working since June on a study that will include an illustrative recounting of major recent achievements; identification of new opportunities and challenges facing the field; and articulation-for leaders in government, industry, universities, and the public at large-of the important roles played by the field in modern society. An especially urgent issue is how to maintain the intellectual vitality of condensed matter and materials physics, and its contributions to the well-being of the United States, in an era of limited resources. The forum will feature a panel of materials researchers who are members of the Committee on Condensed Matter and Materials Physics. They will give a brief report on the status of the study and engage in a dialogue with the audience about issues facing the condensed matter and materials physics community. Broad community input is vital to the success of the study. Please come and make your voice heard!

  10. Flat-detector computed tomography (FD-CT).

    PubMed

    Kalender, Willi A; Kyriakou, Yiannis

    2007-11-01

    Flat-panel detectors or, synonymously, flat detectors (FDs) have been developed for use in radiography and fluoroscopy with the defined goal to replace standard X-ray film, film-screen combinations and image intensifiers by an advanced sensor system. FD technology in comparison to X-ray film and image intensifiers offers higher dynamic range, dose reduction, fast digital readout and the possibility for dynamic acquisitions of image series, yet keeping to a compact design. It appeared logical to employ FD designs also for computed tomography (CT) imaging. Respective efforts date back a few years only, but FD-CT has meanwhile become widely accepted for interventional and intra-operative imaging using C-arm systems. FD-CT provides a very efficient way of combining two-dimensional (2D) radiographic or fluoroscopic and 3D CT imaging. In addition, FD technology made its way into a number of dedicated CT scanner developments, such as scanners for the maxillo-facial region or for micro-CT applications. This review focuses on technical and performance issues of FD technology and its full range of applications for CT imaging. A comparison with standard clinical CT is of primary interest. It reveals that FD-CT provides higher spatial resolution, but encompasses a number of disadvantages, such as lower dose efficiency, smaller field of view and lower temporal resolution. FD-CT is not aimed at challenging standard clinical CT as regards to the typical diagnostic examinations; but it has already proven unique for a number of dedicated CT applications, offering distinct practical advantages, above all the availability of immediate CT imaging in the interventional suite or the operating room.

  11. An integrated control panel utilizing a programmable varistor-multiplexed dichroic liquid crystal display

    NASA Technical Reports Server (NTRS)

    Whitton, I. J.

    1981-01-01

    Due to the conflicting demands of modern aircraft for increased systems/sensors and the decrease in cockpit panel size, weight, volume, and power, conventional discrete/dedicated methods of display and control are fast becoming obsolete. A means is sought to integrate the control and display into multifunctional programmable devices, thus giving the ability to increase system functions and yet conserve panel space. A potential solution to the control portion of the problem has come to be known as the Integrated Control Panel (ICP) approach. Flat panel display technology and controls using programmable flat panel displays with transparent capacitive touch control overlays offer the largest potential advantages. The flat panel display made of varistor-multiplexed dichroic liquid crystal (LCD) developed by GE in recent years appears to offer the ideal monochrome solution.

  12. Tailorable advanced blanket insulation using aluminoborosilicate and alumina batting

    NASA Technical Reports Server (NTRS)

    Calamito, Dominic P.

    1989-01-01

    Two types of Tailorable Advanced Blanket Insulation (TABI) flat panels for Advanced Space Transportation Systems were produced. Both types consisted of integrally woven, 3-D fluted core having parallel faces and connecting ribs of Nicalon yarns. The triangular cross section flutes of one type was filled with mandrels of processed Ultrafiber (aluminoborosilicate) stitchbonded Nextel 440 fibrous felt, and the second type wall filled with Saffil alumina fibrous felt insulation. Weaving problems were minimal. Insertion of the fragile insulation mandrels into the fabric flutes was improved by using a special insertion tool. An attempt was made to weave fluted core fabrics from Nextel 440 yarns but was unsuccessful because of the yarn's fragility. A small sample was eventually produced by an unorthodox weaving process and then filled with Saffil insulation. The procedures for setting up and weaving the fabrics and preparing and inserting insulation mandrels are discussed. Characterizations of the panels produced are also presented.

  13. Poker Flat improvements

    NASA Astrophysics Data System (ADS)

    The U.S. Senate Appropriations Committee approved on September 14 a $10.8 million upgrade to University of Alaska Fairbanks Poker Flat Research Range pending full House and Senate approval. The funding will provide for building design, scientific program planning, and initial road and foundation construction. Senator Ted Stevens (RAK) said, “It is an important recognition of the roles Poker Flat, the Geophysical Institute and this university play in the international science area,“ that the Senate approved the money in a time of budget pressure.Poker Flat's facilities include rocket assembly and launching capabilities, telemetry receiving stations and ground-based diagnostic systems needed for launch decisions for space, aeronomy and atmospheric science experiments.

  14. Advanced High School Biology in an Era of Rapid Change: A Summary of the Biology Panel Report from the NRC Committee on Programs for Advanced Study of Mathematics and Science in American High Schools

    ERIC Educational Resources Information Center

    Wood, William B.

    2002-01-01

    A recently released National Research Council (NRC) report, "Learning and Understanding: Improving Advanced Study of Mathematics and Science in U.S. High Schools", evaluated and recommended changes in the Advanced Placement (AP), International Baccalaureate (IB), and other advanced secondary school science programs. As part of this study,…

  15. Flat Focusing Mirror

    PubMed Central

    Cheng, Y. C.; Kicas, S.; Trull, J.; Peckus, M.; Cojocaru, C.; Vilaseca, R.; Drazdys, R.; Staliunas, K.

    2014-01-01

    The control of spatial propagation properties of narrow light beams such as divergence, focusing or imaging are main objectives in optics and photonics. In this letter, we propose and demonstrate experimentally a flat focusing mirror, based on an especially designed dielectric structure without any optical axis. More generally, it also enables imaging any light pattern in reflection. The flat focusing mirror with a transversal invariance can largely increase the applicability of structured photonic materials for light beam propagation control in small-dimension photonic circuits. PMID:25228358

  16. Holograms of Flat Space

    NASA Astrophysics Data System (ADS)

    Bagchi, Arjun; Grumiller, Daniel

    2013-07-01

    The holographic principle has a concrete realization in the Anti-de Sitter/Conformal Field Theory (AdS/CFT) correspondence. If this principle is a true fact about quantum gravity then it must also hold beyond AdS/CFT. In this paper, we address specifically holographic field theory duals of gravitational theories in asymptotically flat spacetimes. We present some evidence of our recent conjecture that three-dimensional (3d) conformal Chern-Simons gravity (CSG) with flat space boundary conditions is dual to an extremal CFT.

  17. Flat early cancers of the large intestine.

    PubMed

    Kuramoto, S; Oohara, T

    1989-08-15

    From January 1976 to December 1987, 37 early colorectal cancers of the flat type were treated. Thirty-four of them (91.9%) were not accompanied by adenoma, and were thought to have arisen de novo. There is indeed a de novo route of cancer development in the human large intestine, and cancers de novo merely show polypoid growth. Flat type cancers arising de novo tend to reach deeper layers at an earlier stage than polypoid-type carcinomas in adenoma. Of those with a diameter of less than 10 mm, only 40% stayed in the mucosa. Consequently, advanced cancers cannot be prevented by snare polypectomy alone. More attention should be directed to the discovery of small, flat, nonpolypoid cancers.

  18. Design of an efficient projector for LED flat lamp without light guide plate

    NASA Astrophysics Data System (ADS)

    Lai, Li-ping; Zhuang, Qi-ren; Liang, De-juan

    2013-11-01

    An efficient LED projector is designed for the LED flat lamp without light guide plate (LGP), in order to get high-efficiency lighting capablility and low cost of LED flat lamp. By employing refraction and total reflection, uniform intensity distribution of the emergent light and high-efficiency lighting capablility are achieved. The simulation results show that the output efficiency and intensity distribution on LED flat lamp panel depend on the distance between projector and output panel, the rotation angle of the projector and the gap between projector and LED. It performs well in both lighting efficiency and uniformity, while a distance of 5 mm, a rotation angle of 2° and a gap of 1.2 mm are used with the panel size of 240 mm×360 mm in the LED flat lamp without LGP. And 96.6% of optical uniformity is achieved.

  19. Flat-cable fabrication

    NASA Astrophysics Data System (ADS)

    Groot, K. J.

    1982-11-01

    Processes, environment, designs, and materials were reviewed to lower the attrition rate and improve the manufacturing ability of flat, flexible cables. Attrition caused by foreign material, damage, and dents was lowered. A new termination was developed for two cables. An alternative design for Kapton insulated cables reduced notch sensitivity. Alternative methods of cable manufacturing and inspection are investigated.

  20. Is flat fair?

    SciTech Connect

    Bunzl, Martin

    2010-07-15

    Dynamic pricing holds out the promise of shifting peak demand as well as reducing overall demand. But it also raises thorny issues of fairness. All practical pricing systems involve tradeoffs between equity and efficiency. I examine the circumstances under which equity ought to be allowed to trump efficiency and whether or not this constitutes a defense of flat pricing. (author)

  1. Multilayer flat electrical cable

    NASA Technical Reports Server (NTRS)

    Silverman, P. G.

    1973-01-01

    Flat electrical cable is lightweight, flexible over wide temperature range, withstands continuous exposure to high levels of nuclear radiation, and can carry high currents with minimum of temperature rise. Its magnetic cleanliness is equal to or better than twisted pair of wires, and it can be terminated in conventional electrical connector.

  2. Brushless Cleaning of Solar Panels and Windows

    NASA Technical Reports Server (NTRS)

    Schneider, H. W.

    1982-01-01

    Machine proposed for cleaning solar panels and reflectors uses multiple vortexes of air, solvent, and water to remove dust and dirt. Uses no brushes that might abrade solar surfaces and thereby reduce efficiency. Machine can be readily automated and can be used on curved surfaces such as aparbolic reflectors as well as on flat ones. Cleaning fluids are recycled, so that large quantities of water and solvent are not needed.

  3. Flat detectors and their clinical applications.

    PubMed

    Spahn, Martin

    2005-09-01

    Diagnostic and interventional flat detector X-ray systems are penetrating the market in all application segments. First introduced in radiography and mammography, they have conquered cardiac and general angiography and are getting increasing attention in fluoroscopy. Two flat detector technologies prevail. The dominating method is based on an indirect X-ray conversion process, using cesium iodide scintillators. It offers considerable advantages in radiography, angiography and fluoroscopy. The other method employs a direct converter such as selenium which is particularly suitable for mammography. Both flat detector technologies are based on amorphous silicon active pixel matrices. Flat detectors facilitate the clinical workflow in radiographic rooms, foster improved image quality and provide the potential to reduce dose. This added value is based on their large dynamic range, their high sensitivity to X-rays and the instant availability of the image. Advanced image processing is instrumental in these improvements and expand the range of conventional diagnostic methods. In angiography and fluoroscopy the transition from image intensifiers to flat detectors is facilitated by ample advantages they offer, such as distortion-free images, excellent coarse contrast, large dynamic range and high X-ray sensitivity. These characteristics and their compatibility with strong magnetic fields are the basis for improved diagnostic methods and innovative interventional applications.

  4. APPLIED ORIGAMI. Origami of thick panels.

    PubMed

    Chen, Yan; Peng, Rui; You, Zhong

    2015-07-24

    Origami patterns, including the rigid origami patterns in which flat inflexible sheets are joined by creases, are primarily created for zero-thickness sheets. In order to apply them to fold structures such as roofs, solar panels, and space mirrors, for which thickness cannot be disregarded, various methods have been suggested. However, they generally involve adding materials to or offsetting panels away from the idealized sheet without altering the kinematic model used to simulate folding. We develop a comprehensive kinematic synthesis for rigid origami of thick panels that differs from the existing kinematic model but is capable of reproducing motions identical to that of zero-thickness origami. The approach, proven to be effective for typical origami, can be readily applied to fold real engineering structures.

  5. Graphite/epoxy orthogrid panel fabrication

    NASA Technical Reports Server (NTRS)

    Lager, J. R.

    1978-01-01

    The structural concept considered for a spacecraft body structure is a grid stiffened skin with a skin laminate configuration and the stiffener grid geometry selected to best suit the design requirements. The orthogrid panel developed weighs 0.55 lb/sq ft and resisted an ultimate in-plane shear load of 545 lbf/in. The basic concept of a grid stiffener composite panel is that a relatively thin skin is reinforced with a gridwork of stiffeners so that the overall panel can resist design loads without becoming structurally unstable or being overstressed. The main feature of the orthogrid panel design is that it provides the potential for low cost structural panels when advanced to the production phase. The most innovative part of the fabrication method is the foam/fiberglass stiffener web grid billet fabrication and machining to size.

  6. Flat Surface Damage Detection System (FSDDS)

    NASA Technical Reports Server (NTRS)

    Williams, Martha; Lewis, Mark; Gibson, Tracy; Lane, John; Medelius, Pedro; Snyder, Sarah; Ciarlariello, Dan; Parks, Steve; Carrejo, Danny; Rojdev, Kristina

    2013-01-01

    The Flat Surface Damage Detection system (FSDDS} is a sensory system that is capable of detecting impact damages to surfaces utilizing a novel sensor system. This system will provide the ability to monitor the integrity of an inflatable habitat during in situ system health monitoring. The system consists of three main custom designed subsystems: the multi-layer sensing panel, the embedded monitoring system, and the graphical user interface (GUI). The GUI LABVIEW software uses a custom developed damage detection algorithm to determine the damage location based on the sequence of broken sensing lines. It estimates the damage size, the maximum depth, and plots the damage location on a graph. Successfully demonstrated as a stand alone technology during 2011 D-RATS. Software modification also allowed for communication with HDU avionics crew display which was demonstrated remotely (KSC to JSC} during 2012 integration testing. Integrated FSDDS system and stand alone multi-panel systems were demonstrated remotely and at JSC, Mission Operations Test using Space Network Research Federation (SNRF} network in 2012. FY13, FSDDS multi-panel integration with JSC and SNRF network Technology can allow for integration with other complementary damage detection systems.

  7. Panel Resource Management (PRM) Implementation and Effects within Safety Review Panel Settings and Dynamics

    NASA Technical Reports Server (NTRS)

    Taylor, Robert W.; Nash, Sally K.

    2007-01-01

    While technical training and advanced degree's assure proficiency at specific tasks within engineering disciplines, they fail to address the potential for communication breakdown and decision making errors familiar to multicultural environments where language barriers, intimidating personalities and interdisciplinary misconceptions exist. In an effort to minimize these pitfalls to effective panel review, NASA's lead safety engineers to the ISS Safety Review Panel (SRP), and Payload Safety Review Panel (PSRP) initiated training with their engineers, in conjunction with the panel chairs, and began a Panel Resource Management (PRM) program. The intent of this program focuses on the ability to reduce the barriers inhibiting effective participation from all panel attendees by bolstering participants confidence levels through increased communication skills, situational awareness, debriefing, and a better technical understanding of requirements and systems.

  8. Advanced and tendencies in the development of display technologies

    NASA Astrophysics Data System (ADS)

    Kompanets, I. N.

    2006-06-01

    Advances and key display applications are discussed. Computer, compact mobile, TV and collective large screen displays are mentioned. Flat panel displays step on CRT devices to leave them behind in 2007. Materials, active matricies and applications of bright radiative field emission and organic LED displays are developing successively and pressing other technologies to be used in photo-cameras, cellular phones, auto-cars and avionics. Progress in flexible screens can substantially extend the display design and application soon. 3D display systems are under intensive development, and laser is an important unit in some vaiants of holographic and volumetric 3D displays. Value forecast of different display markets is presented.

  9. Thermal conductivity of Rene 41 honeycomb panels

    NASA Astrophysics Data System (ADS)

    Deriugin, V.

    1980-12-01

    Effective thermal conductivities of Rene 41 panels suitable for advanced space transportation vehicle structures were determined analytically and experimentally for temperature ranges between 20.4K (423 F) and 1186K (1675 F). The cryogenic data were obtained using a cryostat whereas the high temperature data were measured using a heat flow meter and a comparative thermal conductivity instrument respectively. Comparisons were made between analysis and experimental data. Analytical methods appear to provide reasonable definition of the honeycomb panel effective thermal conductivities.

  10. Cooled Panel With Thermostats In All Passages

    NASA Technical Reports Server (NTRS)

    Blosser, Max L.; Kelly, H. Neale

    1994-01-01

    Simple shape-memory-alloy or bimaterial thermostatic valve incorporated in each passage of multiple-passage cooled panel, according to proposal. Thermostatic valves all set to same opening/closing temperature, so they regulate flows in all passages to equalize or nearly equalize temperature across panel in presence of transient, nonuniform surface heating. Concept beneficial in application in which overheating causes damage and both overcooling and excessive circulation of coolant occurs in absence of regulation if cooling capacity of panel made large enough to handle peak heat load. Potential applications include cooled structures for advanced hypersonic aircraft and engines.

  11. Hepatitis virus panel

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/003558.htm Hepatitis virus panel To use the sharing features on this page, please enable JavaScript. The hepatitis virus panel is a series of blood tests used ...

  12. Treatment of advanced non-small-cell lung cancer with epidermal growth factor receptor (EGFR) mutation or ALK gene rearrangement: results of an international expert panel meeting of the Italian Association of Thoracic Oncology.

    PubMed

    Gridelli, Cesare; de Marinis, Filippo; Cappuzzo, Federico; Di Maio, Massimo; Hirsch, Fred R; Mok, Tony; Morgillo, Floriana; Rosell, Rafael; Spigel, David R; Yang, James Chih-Hsin; Ciardiello, Fortunato

    2014-05-01

    The availability of targeted drugs has made the assessment of the EGFR mutation and ALK rearrangement critical in choosing the optimal treatment for patients with advanced non-small-cell lung cancer (NSCLC). In May 2013, the Italian Association of Thoracic Oncology (AIOT) organized an International Experts Panel Meeting to review strengths and limitations of the available evidence for the diagnosis and treatment of advanced NSCLC with EGFR or anaplastic lymphoma kinase (ALK) alterations and to discuss implications for clinical practice and future clinical research. All patients with advanced NSCLC, with the exclusion of pure squamous cell carcinoma in former or current smokers, should be tested for EGFR mutations and ALK rearrangements before decisions are made on first-line treatment. First-line treatment of EGFR-mutated cases should be with an EGFR tyrosine kinase inhibitor (TKI). Any available agent (gefitinib, erlotinib, or afatinib) can be used, until further data from comparative studies may better guide TKI selection. As general rule, and when clinically feasible, results of EGFR mutational status should be awaited before starting first-line treatment. Panelists agreed that the use of crizotinib is justified in any line of treatment. Although solid evidence supporting the continuation of EGFR TKIs or crizotinib beyond progression is lacking, in some cases (minimal, asymptomatic progression, or oligoprogression manageable by local therapy), treatment continuation beyond progression could be justified. Experimental strategies to target tumor heterogeneity and to treat patients after failure of EGFR TKIs or crizotinib are considered high-priority areas of research. A number of relevant research priorities were identified to optimize available treatment options.

  13. Flat conductor cable commercialization project

    NASA Technical Reports Server (NTRS)

    Hogarth, P.; Wadsworth, E.

    1977-01-01

    An undercarpet flat conductor cable and a baseboard flat conductor cable system were studied for commercialization. The undercarpet system is designed for use in office and commercial buildings. It employs a flat power cable, protected by a grounded metal shield, that terminates in receptacles mounted on the floor. It is designed to interface with a flat conductor cable telephone system. The baseboard system consists of a flat power cable mounted in a plastic raceway; both the raceway and the receptacles are mounted on the surface of the baseboard. It is designed primarily for use in residential buildings, particularly for renovation and concrete and masonry construction.

  14. Comprehensive metabolic panel

    MedlinePlus

    Metabolic panel - comprehensive; Chem-20; SMA20; Sequential multi-channel analysis with computer-20; SMAC20; Metabolic panel 20 ... McPherson RA, Pincus MR. Disease/organ panels. McPherson RA, ... . 22nd ed. Philadelphia, PA: Elsevier Saunders; 2011:appendix 7.

  15. Reinforced Honeycomb Panels

    NASA Technical Reports Server (NTRS)

    Bhat, Balakrishna T.; Akutagawa, Wesley; Wang, Taylor G.; Barber, Dan

    1989-01-01

    New honeycomb panel structure has increased strength and stiffness with little increase in weight. Some or all of walls of honeycomb cells reinforced with honeycomb panels having smaller cells, lightweight foam, or other reinforcing material. Strong, lightweight reinforced panels used in aircraft, car and truck bodies, cabinets for equipment and appliances, and buildings.

  16. TRMM Solar Array Panels

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This final report presents conclusions/recommendations concerning the TRMM Solar Array; deliverable list and schedule summary; waivers and deviations; as-shipped performance data, including flight panel verification matrix, panel output detail, shadow test summary, humidity test summary, reverse bias test panel; and finally, quality assurance summary.

  17. Modal response and noise transmission of composite panels

    NASA Technical Reports Server (NTRS)

    Grosveld, F. W.; Metcalf, V. L.

    1985-01-01

    Noise transmission through flat, angular, fiber-reinforced composite panels is investigated experimentally and analytically. A modal decomposition technique was used to obtain solutions to the governing differential equation of motion. Experimental modal analysis was performed in order to confirm the theoretical results. The test specimens were cross-ply and angle-ply composite panels made of various concentrations of fiberglass, graphite, or aramid fibers embedded in epoxy resion. The experimental results showed good agreement with the theoretical calculations. Graphs of the transmission loss characteristics of the different composite panels are provided.

  18. Cryogenic performance of slotted brazed Rene 41 honeycomb panels

    NASA Technical Reports Server (NTRS)

    Hepler, A. K.; Swegle, A. R.

    1982-01-01

    Two brazed Rene 41 honeycomb panels that would incorporate a frame element were designed, fabricated and tested. The panels were representative of the lower surface of an advanced space transportation vehicle. The first panel was a two span panel supported by a center frame and on edges parallel to it. The second panel was a two span panel supported by a center frame and on edges parallel to it. The second panel was a three span panel supported on two frames and on edges parallel to the frames. Each panel had its outer skin slotted to reduce the thermal stresses of the panel skins. The first panel was tested under simulated boost conditions that included liquid hydrogen exposure of the frame and inner skin and radiant heat to 478K on the outer skins. The first panel was tested to investigate the effect of thermal stresses in skins and core caused by the panel being restrained by a cold integral frame and to observe the effects of frost formation and possible liquid air development in and around outer skin slots.

  19. Asymptotically flat multiblack lenses

    NASA Astrophysics Data System (ADS)

    Tomizawa, Shinya; Okuda, Taika

    2017-03-01

    We present an asymptotically flat and stationary multiblack lens solution with biaxisymmetry of U (1 )×U (1 ) as a supersymmetric solution in the five-dimensional minimal ungauged supergravity. We show that the spatial cross section of each degenerate Killing horizon admits different lens space topologies of L (n ,1 )=S3/Zn as well as a sphere S3. Moreover, we show that, in contrast to the higher-dimensional Majumdar-Papapetrou multiblack hole and multi-Breckenridge-Myers-Peet-Vafa (BMPV) black hole spacetime, the metric is smooth on each horizon even if the horizon topology is spherical.

  20. Buckling of open-section bead-stiffened composite panels

    NASA Astrophysics Data System (ADS)

    Laananen, D. H.; Renze, S. P.

    Stiffened panels are structures that can be designed to efficiently support inplane compression, bending, and shear loads. Although the stiffeners are usually discrete elements which are fastened or bonded to a flat or continuously curved plate, manufacturing methods such as thermoforming allow integral formation of the stiffeners in a panel. Such a configuration offers potential advantages in terms of a reduced number of parts and manufacturing operations. For thermoplastic composite panels stiffened by integrally formed open-section beads, the effects of bead spacing and bend cross-section geometry on the initiation of buckling under uniaxial compression and uniform shear loading were investigated. Finite elements results for a range of stiffened panel sizes and bead geometries are presented and compared with approximate closed-form solutions based on an effective flat plate size. Experimental verification of analytical predictions for one of the shear panels and one of the compression panels is described. Compensation of the forming tool to reduce the degree of initial curvature of the panels was found to be necessary.

  1. Safety Panel Resources

    NASA Technical Reports Server (NTRS)

    Stewart, Christine E.

    2008-01-01

    The goal of this paper is to explore what resources are potentially available to safety panels and to provide some guidance on how to utilize those resources. While the examples used in this paper will concentrate on the Flight Equipment and Reliability Review Panel (FESRRP) and Extravehicular Activity (EVA) hardware that have come through that panel, as well as resources at Johnson Space Center, the paper will address how this applies to safety panels in general, and where possible cite examples for other safety panels.

  2. Analysis and test of superplastically formed titanium hat-stiffened panels under compression

    NASA Technical Reports Server (NTRS)

    Davis, Randall C.; Royster, Dick M.; Bales, Thomas T.

    1987-01-01

    Four hat-stiffened titanium panels with two different stiffener configurations were fabricated by superplastic forming/weld brazing and tested under a moderately heavy compressive load. The panels had the same overall dimensions but differed in the shape of the hat-stiffener webs; three panels had stiffeners with flat webs and the other panel had stiffeners with beaded webs. Analysis indicated that the local buckling strain of the flat stiffener web was considerably lower than the general panel buckling strain or cap buckling strain. The analysis also showed that beading the webs of the hat stiffeners removed them as the critical element for local buckling and improved the buckling strain of the panels. The analytical extensional stiffness and failure loads compared very well with experimental results.

  3. 19. VIEW OF THE PLATING BATHS AND CONTROL PANELS. GOLD ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    19. VIEW OF THE PLATING BATHS AND CONTROL PANELS. GOLD AND SILVER WERE AMONG THE MATERIALS PLATED ONTO PARTS MADE OF COPPER, STAINLESS STEEL AND STEEL. (11/15/89) - Rocky Flats Plant, Non-Nuclear Production Facility, South of Cottonwood Avenue, west of Seventh Avenue & east of Building 460, Golden, Jefferson County, CO

  4. ICFA neutrino panel report

    NASA Astrophysics Data System (ADS)

    Long, K.

    2015-07-01

    In the summer of 2013 the International Committee on Future Accelerators (ICFA) established a Neutrino Panel with the mandate: "To promote international cooperation in the development of the accelerator-based neutrino-oscillation program and to promote international collaboration in the development of a neutrino factory as a future intense source of neutrinos for particle physics experiments." In its first year the Panel organised a series of regional Town Meetings to collect input from the community and to receive reports from the regional planning exercises. The Panel distilled its findings and presented them in a report to ICFA [1]. In this contribution the formation and composition of the Panel are presented together with a summary of the Panel's findings from the three Regional Town Meetings. The Panel's initial conclusions are then articulated and the steps that the Panel seeks to take are outlined.

  5. Interactive optical panel

    DOEpatents

    Veligdan, J.T.

    1995-10-03

    An interactive optical panel assembly includes an optical panel having a plurality of ribbon optical waveguides stacked together with opposite ends thereof defining panel first and second faces. A light source provides an image beam to the panel first face for being channeled through the waveguides and emitted from the panel second face in the form of a viewable light image. A remote device produces a response beam over a discrete selection area of the panel second face for being channeled through at least one of the waveguides toward the panel first face. A light sensor is disposed across a plurality of the waveguides for detecting the response beam therein for providing interactive capability. 10 figs.

  6. Interactive optical panel

    DOEpatents

    Veligdan, James T.

    1995-10-03

    An interactive optical panel assembly 34 includes an optical panel 10 having a plurality of ribbon optical waveguides 12 stacked together with opposite ends thereof defining panel first and second faces 16, 18. A light source 20 provides an image beam 22 to the panel first face 16 for being channeled through the waveguides 12 and emitted from the panel second face 18 in the form of a viewable light image 24a. A remote device 38 produces a response beam 40 over a discrete selection area 36 of the panel second face 18 for being channeled through at least one of the waveguides 12 toward the panel first face 16. A light sensor 42,50 is disposed across a plurality of the waveguides 12 for detecting the response beam 40 therein for providing interactive capability.

  7. Spectral Flat Fields

    NASA Astrophysics Data System (ADS)

    Kinney, Anne

    1990-12-01

    The diode to diode variations and photocathode non- uniformities of the FOS detectors were determined in SV for spectra obtained through the single apertures. Additional flat field calibrations will be performed in cycle 1 to verify stability and to extend the calibration to include the paired aperture spectra. In this test, we will obtain spectra of G191-B2B, which is known to have a very smooth, relatively featureless spectrum. The star will be observed in every useful detector/disperser combination through single apertures, and with the most useful dispersers at the photocathode locations corresponding to paired aperture spectra. Spatial scanning in the dispersion direction is used to shift the spectra, so that instrumental and features can be distinguished. The most useful polarizer configurations are also calibrated (excluding red side polarimetry and including blue side polarimetry for POL0-B but not for POL0-A). A second star, BD+28D4211, is also observed in the same manner, about 6 months later, to establish photometric and flat-field stability.

  8. 76 FR 60934 - Proposal Review Panel for Human Resource Development; Notice of Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-30

    ... Proposal Review Panel for Human Resource Development; Notice of Meeting In accordance with the Federal... Person: Kelly Mack, Division of Human Resource Development, Room 815, National Science Foundation... following meeting: Name: ADVANCE Institutional Transformation Site Visit; Proposal Review Panel...

  9. 76 FR 60933 - Proposal Review Panel for Human Resource Development; Notice of Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-30

    ... Proposal Review Panel for Human Resource Development; Notice of Meeting In accordance with the Federal... Person: Kelly Mack, Division of Human Resource Development, Room 815, National Science Foundation... following meeting: Name: ADVANCE Institutional Transformation Site Visit, Proposal Review Panel...

  10. Loading and heating of a large flat plate at Mach 7 in the Langley 8-foot high-temperature structures tunnel

    NASA Technical Reports Server (NTRS)

    Deveikis, W. D.; Hunt, L. R.

    1973-01-01

    Surface pressure and cold-wall heating rate distributions (wall-temperature to total-temperature ratio approximately 0.2) were obtained on a large, flat calibration panel at a nominal Mach number of 7 in an 8-foot high-temperature structures tunnel. Panel dimensions were 42.5 by 60.0 in. Test objectives were: (1) to map available flat-plate loading and heating provided by the facility and (2) to determine effectiveness of leading-edge bluntness, boundary-layer trips, and aerodynamic fences in generating a uniform, streamwise turbulent flow field over the test surface of a flat-sided panel holder.

  11. Compressive and shear buckling analysis of metal matrix composite sandwich panels under different thermal environments

    NASA Technical Reports Server (NTRS)

    Ko, William L.; Jackson, Raymond H.

    1993-01-01

    Combined inplane compressive and shear buckling analysis was conducted on flat rectangular sandwich panels using the Raleigh-Ritz minimum energy method with a consideration of transverse shear effect of the sandwich core. The sandwich panels were fabricated with titanium honeycomb core and laminated metal matrix composite face sheets. The results show that slightly slender (along unidirectional compressive loading axis) rectangular sandwich panels have the most desirable stiffness-to-weight ratios for aerospace structural applications; the degradation of buckling strength of sandwich panels with rising temperature is faster in shear than in compression; and the fiber orientation of the face sheets for optimum combined-load buckling strength of sandwich panels is a strong function of both loading condition and panel aspect ratio. Under the same specific weight and panel aspect ratio, a sandwich panel with metal matrix composite face sheets has much higher buckling strength than one having monolithic face sheets.

  12. A higher order panel method for linearized supersonic flow

    NASA Technical Reports Server (NTRS)

    Ehlers, F. E.; Epton, M. A.; Johnson, F. T.; Magnus, A. E.; Rubbert, P. E.

    1979-01-01

    The basic integral equations of linearized supersonic theory for an advanced supersonic panel method are derived. Methods using only linear varying source strength over each panel or only quadratic doublet strength over each panel gave good agreement with analytic solutions over cones and zero thickness cambered wings. For three dimensional bodies and wings of general shape, combined source and doublet panels with interior boundary conditions to eliminate the internal perturbations lead to a stable method providing good agreement experiment. A panel system with all edges contiguous resulted from dividing the basic four point non-planar panel into eight triangular subpanels, and the doublet strength was made continuous at all edges by a quadratic distribution over each subpanel. Superinclined panels were developed and tested on s simple nacelle and on an airplane model having engine inlets, with excellent results.

  13. The behavior of elastic anisotropic laminated composite flat structures subjected to deterministic and random loadings

    NASA Technical Reports Server (NTRS)

    Librescu, Liviu

    1990-01-01

    Within this research project, the following topics were studied: (1) foundation of the refined theory of flat cross-ply laminated composite flat and curved panels as well as their static and dynamic response analysis; (2) foundation of a geometrically-nonlinear shear-deformable theory of composite laminated flat panels including the effect of initial geometric imperfections and its application in the postbuckling analysis; (3) the study of the dynamic response of shear deformable elastic laminated composite panels to deterministic time-dependent external excitations as the sonic boom and explosive blast type-loadings; (4) the study of the dynamic response of shear deformable elastic laminated composite panels to random excitation as e.g. the one produced by a jet noise or by any time-dependent external excitation whose characteristics are expressed in a statistical sense; and (5) the dynamic stability of fiber-reinforced composite flat panels whose materials (due to e.g. an ambient high temperature field) exhibit a time-dependent physical behavior.

  14. Titanium honeycomb panel testing

    NASA Astrophysics Data System (ADS)

    Richards, W. L.; Thompson, Randolph C.

    The paper describes the procedures of thermal mechanical tests carried out at the NASA Dryden Flight Research Facility on two tianium honeycomb wing panels bonded using liquid interface diffusion (LID) technique, and presents the results of these tests. The 58.4 cm square panels consisted of two 0.152-cm-thick Ti 6-2-4-2 face sheets LID-bonded to a 1.9-cm-thick honeycomb core, with bearing plates fastened to the perimeter of the upper and the lower panel surfaces. The panels were instrumented with sensors for measuring surface temperature, strain, and deflections to 315 C and 482 C. Thermal stress levels representative of those encountered during aerodynamic heating were produced by heating the upper panel surface and restraining all four edges. After more than 100 thermal cycles from room temperature to 315 C and 50 cycles from room temperature to 482 C, no significant structural degradation was detected in the panels.

  15. Is classical flat Kasner spacetime flat in quantum gravity?

    NASA Astrophysics Data System (ADS)

    Singh, Parampreet

    2016-05-01

    Quantum nature of classical flat Kasner spacetime is studied using effective spacetime description in loop quantum cosmology (LQC). We find that even though the spacetime curvature vanishes at the classical level, nontrivial quantum gravitational effects can arise. For the standard loop quantization of Bianchi-I spacetime, which uniquely yields universal bounds on expansion and shear scalars and results in a generic resolution of strong singularities, we find that a flat Kasner metric is not a physical solution of the effective spacetime description, except in a limit. The lack of a flat Kasner metric at the quantum level results from a novel feature of the loop quantum Bianchi-I spacetime: quantum geometry induces nonvanishing spacetime curvature components, making it not Ricci flat even when no matter is present. The noncurvature singularity of the classical flat Kasner spacetime is avoided, and the effective spacetime transits from a flat Kasner spacetime in asymptotic future, to a Minkowski spacetime in asymptotic past. Interestingly, for an alternate loop quantization which does not share some of the fine features of the standard quantization, flat Kasner spacetime with expected classical features exists. In this case, even with nontrivial quantum geometric effects, the spacetime curvature vanishes. These examples show that the character of even a flat classical vacuum spacetime can alter in a fundamental way in quantum gravity and is sensitive to the quantization procedure.

  16. Titanium Honeycomb Panel Testing

    NASA Technical Reports Server (NTRS)

    Richards, W. Lance; Thompson, Randolph C.

    1996-01-01

    Thermal-mechanical tests were performed on a titanium honeycomb sandwich panel to experimentally validate the hypersonic wing panel concept and compare test data with analysis. Details of the test article, test fixture development, instrumentation, and test results are presented. After extensive testing to 900 deg. F, non-destructive evaluation of the panel has not detected any significant structural degradation caused by the applied thermal-mechanical loads.

  17. Aerospace safety advisory panel

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This report from the Aerospace Safety Advisory Panel (ASAP) contains findings, recommendations, and supporting material concerning safety issues with the space station program, the space shuttle program, aeronautics research, and other NASA programs. Section two presents findings and recommendations, section three presents supporting information, and appendices contain data about the panel membership, the NASA response to the March 1993 ASAP report, and a chronology of the panel's activities during the past year.

  18. Comparison of Three Methods for Calculating the Compressive Strength of Flat and Slightly Curved Sheet and Stiffener Combinations

    NASA Technical Reports Server (NTRS)

    Lundquist, Eugene E

    1933-01-01

    This report gives a comparison of the accuracy of the three methods for calculating the compressive strength of flat sheet and stiffener combinations such as occur in stressed-skin or monocoque structures for aircraft. Of the three methods based upon various assumptions with regard to the interaction of sheet and stiffener, the method based upon mutual action of the stiffener and an effective width as a column gave the best agreement with the results of the tests. An investigation of the effect of small curvature resulted in the conclusion that the compressive strength of the curved panels is, for all practical purposes, equal to the strength of flat panels except for thick sheet where non-uniform curvature throughout the length may cause the strength of the curved panel to be 10 to 15 percent less than that of a corresponding flat panel.

  19. PANEL LIBRARY AND EDITOR

    NASA Technical Reports Server (NTRS)

    Raible, E.

    1994-01-01

    The Panel Library and Editor is a graphical user interface (GUI) builder for the Silicon Graphics IRIS workstation family. The toolkit creates "widgets" which can be manipulated by the user. Its appearance is similar to that of the X-Windows System. The Panel Library is written in C and is used by programmers writing user-friendly mouse-driven applications for the IRIS. GUIs built using the Panel Library consist of "actuators" and "panels." Actuators are buttons, dials, sliders, or other mouse-driven symbols. Panels are groups of actuators that occupy separate windows on the IRIS workstation. The application user can alter variables in the graphics program, or fire off functions with a click on a button. The evolution of data values can be tracked with meters and strip charts, and dialog boxes with text processing can be built. Panels can be stored as icons when not in use. The Panel Editor is a program used to interactively create and test panel library interfaces in a simple and efficient way. The Panel Editor itself uses a panel library interface, so all actions are mouse driven. Extensive context-sensitive on-line help is provided. Programmers can graphically create and test the user interface without writing a single line of code. Once an interface is judged satisfactory, the Panel Editor will dump it out as a file of C code that can be used in an application. The Panel Library (v9.8) and Editor (v1.1) are written in C-Language (63%) and Scheme, a dialect of LISP, (37%) for Silicon Graphics 4D series workstations running IRIX 3.2 or higher. Approximately 10Mb of disk space is required once compiled. 1.5Mb of main memory is required to execute the panel editor. This program is available on a .25 inch streaming magnetic tape cartridge in UNIX tar format for an IRIS, and includes a copy of XScheme, the public-domain Scheme interpreter used by the Panel Editor. The Panel Library Programmer's Manual is included on the distribution media. The Panel Library and

  20. Solar reflection panels

    DOEpatents

    Diver, Jr., Richard B.; Grossman, James W.; Reshetnik, Michael

    2006-07-18

    A solar collector comprising a glass mirror, and a composite panel, wherein the back of the mirror is affixed to a front surface of the composite panel. The composite panel comprises a front sheet affixed to a surface of a core material, preferably a core material comprising a honeycomb structure, and a back sheet affixed to an opposite surface of the core material. The invention may further comprise a sealing strip, preferably comprising EPDM, positioned between the glass mirror and the front surface of the composite panel. The invention also is of methods of making such solar collectors.

  1. Pressure Testing of a Minimum Gauge PRSEUS Panel

    NASA Technical Reports Server (NTRS)

    Lovejoy, Andrew J.; Rouse, Marshall; Linton, Kim A.; Li, Victor P.

    2011-01-01

    Advanced aircraft configurations that have been developed to increase fuel efficiency require advanced, novel structural concepts capable of handling the unique load conditions that arise. One such concept is the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) developed by the Boeing Company. The PRSEUS concept is being investigated by NASA s Environmentally Responsible Aviation (ERA) Program for use in a hybrid-wing body (HWB) aircraft. This paper summarizes the analysis and test of a PRSEUS panel subjected to internal pressure, the first such pressure test for this structural concept. The pressure panel used minimum gauge skin, with stringer and frame configurations consistent with previous PRSEUS tests. Analysis indicated that for the minimum gauge skin panel, the stringer locations exhibit fairly linear response, but the skin bays between the stringers exhibit nonlinear response. Excellent agreement was seen between nonlinear analysis and test results in the critical portion at the center of the panel. The pristine panel was capable of withstanding the required 18.4 psi pressure load condition without exhibiting any damage. The impacted panel was capable of withstanding a pressure load in excess of 28 psi before initial failure occurred at the center stringer, and the panel was capable of sustaining increased pressure load after the initial failure. This successful PRSEUS panel pressure panel test was a critical step in the building block approach for enabling the use of this advanced structural concept on future aircraft, such as the HWB.

  2. 78 FR 22345 - Meetings of Humanities Panel

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-15

    ... applications for the Institutes for Advanced Topics in the Digital Humanities grant program, submitted to the Office of Digital Humanities. Because these meetings will include review of personal and/or proprietary... ARTS AND THE HUMANITIES Meetings of Humanities Panel AGENCY: National Endowment for the...

  3. Postbuckling behavior of graphite-epoxy panels

    NASA Technical Reports Server (NTRS)

    Starnes, J. H., Jr.; Dickson, J. N.; Rouse, M.

    1984-01-01

    Structurally efficient fuselage panels are often designed to allow buckling to occur at applied loads below ultimate. Interest in applying graphite-epoxy materials to fuselage primary structure led to several studies of the post-buckling behavior of graphite-epoxy structural components. Studies of the postbuckling behavior of flat and curved, unstiffened and stiffened graphite-epoxy panels loaded in compression and shear were summarized. The response and failure characteristics of specimens studied experimentally were described, and analytical and experimental results were compared. The specimens tested in the studies described were fabricated from commercially available 0.005-inch-thick unidirectional graphite-fiber tapes preimpregnated with 350 F cure thermosetting epoxy resins.

  4. Absolute calibration of optical flats

    DOEpatents

    Sommargren, Gary E.

    2005-04-05

    The invention uses the phase shifting diffraction interferometer (PSDI) to provide a true point-by-point measurement of absolute flatness over the surface of optical flats. Beams exiting the fiber optics in a PSDI have perfect spherical wavefronts. The measurement beam is reflected from the optical flat and passed through an auxiliary optic to then be combined with the reference beam on a CCD. The combined beams include phase errors due to both the optic under test and the auxiliary optic. Standard phase extraction algorithms are used to calculate this combined phase error. The optical flat is then removed from the system and the measurement fiber is moved to recombine the two beams. The newly combined beams include only the phase errors due to the auxiliary optic. When the second phase measurement is subtracted from the first phase measurement, the absolute phase error of the optical flat is obtained.

  5. Thermal Performance Evaluation of Walls with Gas Filled Panel Insulation

    SciTech Connect

    Shrestha, Som S.; Desjarlais, Andre Omer; Atchley, Jerald Allen

    2014-11-01

    Gas filled insulation panels (GFP) are very light weight and compact (when uninflated) advanced insulation products. GFPs consist of multiple layers of thin, low emittance (low-e) metalized aluminum. When expanded, the internal, low-e aluminum layers form a honeycomb structure. These baffled polymer chambers are enveloped by a sealed barrier and filled with either air or a low-conductivity gas. The sealed exterior aluminum foil barrier films provide thermal resistance, flammability protection, and properties to contain air or a low conductivity inert gas. This product was initially developed with a grant from the U.S. Department of Energy. The unexpanded product is nearly flat for easy storage and transport. Therefore, transportation volume and weight of the GFP to fill unit volume of wall cavity is much smaller compared to that of other conventional insulation products. This feature makes this product appealing to use at Army Contingency Basing, when transportation cost is significant compared to the cost of materials. The objective of this study is to evaluate thermal performance of walls, similar to those used at typical Barracks Hut (B-Hut) hard shelters, when GFPs are used in the wall cavities. Oak Ridge National Laboratory (ORNL) tested performance of the wall in the rotatable guarded hotbox (RGHB) according to the ASTM C 1363 standard test method.

  6. On-grade insulated panel floor system

    SciTech Connect

    Bjornson, D.; Briscoe, J.; Brown, G.Z.; Fremouw, S.; Kline, J.; Northcutt, D.

    1999-07-01

    The on-grade insulated panel floor system combines floor and foundation to reduce cost, increase energy and structural performance, and provide easy dismantling and recycling upon demolition. The system uses one-sided structural insulated panels (SIPs with one layer of OSB attached to foam insulation), a compacted gravel bed, and engineered lumber for the perimeter beam. Tests show that an on-grade panel floor system of 20 ft by 36 ft (6.1 by 11.0 m) is $895 less expensive and has a 55% better insulating value than an insulated concrete slab, exceeds deflection and flatness criteria for wood and concrete slab floors and supports structural loads in excess of those in residential construction. The flexible nature of the foam and wood may also improve the standing comfort of the floor compared to a concrete slab floor. In addition, the panel and engineered wood components increase the recyclability of the floor. The system is easily adaptable to use over an existing concrete floor.

  7. Flexible optical panel

    DOEpatents

    Veligdan, James T.

    2001-01-01

    A flexible optical panel includes laminated optical waveguides, each including a ribbon core laminated between cladding, with the core being resilient in the plane of the core for elastically accommodating differential movement thereof to permit winding of the panel in a coil.

  8. SNP panels/Imputation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Participants from thirteen countries discussed services that Interbull can perform or recommendations that Interbull can make to promote harmonization and assist member countries in improving their genomic evaluations in regard to SNP panels and imputation. The panel recommended: A mechanism to shar...

  9. New mineral physics panels

    NASA Astrophysics Data System (ADS)

    The AGU Committee on Mineral Physics has formed itself into six panels. The committee chairman is Orson L. Anderson of the Department of Earth and Space Sciences, University of California, Los Angeles; foreign secretary is Robert Liebermann, Department of Earth and Space Sciences, State University of New York, Stony Brook. The six panels are as follows.

  10. Reinventing the solar panel

    SciTech Connect

    Scanlon, M.

    1995-08-01

    This article discusses new technology in solar panels. PowerSource is a solar collector which not only is less expensive than conventional panels to purchase and install, but also increases the electrical output by almost 20%. This article describes the results of testing this system.

  11. 40 CFR 230.42 - Mud flats.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Aquatic Sites § 230.42 Mud flats. (a) Mud flats are broad flat areas along the sea coast and in coastal rivers to the head of tidal influence and in inland lakes, ponds, and riverine systems. When mud flats are inundated, wind and wave action may resuspend bottom sediments. Coastal mud flats are exposed...

  12. ICFA neutrino panel report

    SciTech Connect

    Long, K.

    2015-07-15

    In the summer of 2013 the International Committee on Future Accelerators (ICFA) established a Neutrino Panel with the mandate: <<>>In its first year the Panel organised a series of regional Town Meetings to collect input from the community and to receive reports from the regional planning exercises. The Panel distilled its findings and presented them in a report to ICFA [1]. In this contribution the formation and composition of the Panel are presented together with a summary of the Panel’s findings from the three Regional Town Meetings. The Panel’s initial conclusions are then articulated and the steps that the Panel seeks to take are outlined.

  13. Aerospace Safety Advisory Panel

    NASA Astrophysics Data System (ADS)

    1993-03-01

    The Aerospace Safety Advisory Panel (ASAP) provided oversight on the safety aspects of many NASA programs. In addition, ASAP undertook three special studies. At the request of the Administrator, the panel assessed the requirements for an assured crew return vehicle (ACRV) for the space station and reviewed the organization of the safety and mission quality function within NASA. At the behest of Congress, the panel formed an independent, ad hoc working group to examine the safety and reliability of the space shuttle main engine. Section 2 presents findings and recommendations. Section 3 consists of information in support of these findings and recommendations. Appendices A, B, C, and D, respectively, cover the panel membership, the NASA response to the findings and recommendations in the March 1992 report, a chronology of the panel's activities during the reporting period, and the entire ACRV study report.

  14. Aerospace Safety Advisory Panel

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The Aerospace Safety Advisory Panel (ASAP) provided oversight on the safety aspects of many NASA programs. In addition, ASAP undertook three special studies. At the request of the Administrator, the panel assessed the requirements for an assured crew return vehicle (ACRV) for the space station and reviewed the organization of the safety and mission quality function within NASA. At the behest of Congress, the panel formed an independent, ad hoc working group to examine the safety and reliability of the space shuttle main engine. Section 2 presents findings and recommendations. Section 3 consists of information in support of these findings and recommendations. Appendices A, B, C, and D, respectively, cover the panel membership, the NASA response to the findings and recommendations in the March 1992 report, a chronology of the panel's activities during the reporting period, and the entire ACRV study report.

  15. Advanced stitching technology

    NASA Technical Reports Server (NTRS)

    Scardino, Frank L.

    1992-01-01

    In the design of textile composites, the selection of materials and constructional techniques must be matched with product performance, productivity, and cost requirements. Constructional techniques vary. A classification of various textile composite systems is given. In general, the chopped fiber system is not suitable for structural composite applications because of fiber discontinuity, uncontrolled fiber orientation and a lack of fiber integration or entanglement. Linear filament yarn systems are acceptable for structural components which are exposed to simple tension in their applications. To qualify for more general use as structural components, filament yarn systems must be multi-directionally positioned. With the most sophisticated filament winding and laying techniques, however, the Type 2 systems have limited potential for general load-bearing applications because of a lack of filament integration or entanglement, which means vulnerability to splitting and delamination among filament layers. The laminar systems (Type 3) represented by a variety of simple fabrics (woven, knitted, braided and nonwoven) are especially suitable for load-bearing panels in flat form and for beams in a roled up to wound form. The totally integrated, advanced fabric system (Type 4) are thought to be the most reliable for general load-bearing applications because of fiber continuity and because of controlled multiaxial fiber orientation and entanglement. Consequently, the risk of splitting and delamination is minimized and practically omitted. Type 4 systems can be woven, knitted, braided or stitched through with very special equipment. Multiaxial fabric technologies are discussed.

  16. Flat H Redundant Frangible Joint Development

    NASA Technical Reports Server (NTRS)

    Brown, Chris

    2016-01-01

    changes to better disperse loads paths and to minimize air gaps. The design additionally added more structural strength to enhance the structural limits in static loads testing. The design also implemented a smoother load line through the assembly. Results / Knowledge Gained The new Flat H RFJ successfully fractured at WSTF with thicker ligaments and lower cord size. Where failure to separate occurred earlier, there is now excessive energy available for structural separation. The new challenge to provide some structural support to prevent secondary fracturing of the break plate remains to be completed. This future work is being funded by the JSC Engineering Directorate in 2017 to elevate the TRL on curved Flat H RFJs that configure with the Orion Service Panel Separation. Additional funding from JSC Engineering will provide new design testing to avoid secondary fracturing.

  17. Manufacturing process of a multifunctional composite panel with nanocharged matrix

    NASA Astrophysics Data System (ADS)

    Volponi, R.; Spena, P.; De Nicola, F.; Guadagno, L.; Raimondo, M.; Vietri, U.

    2016-05-01

    This paper proposes an effective manufacturing process developed to overcome drawbacks that can occur using a nanofilled resin as matrix in aeronautical composites. Nanoparticles embedded in epoxy resins impregnating carbon fibers are able to improve a composite with new desired functionalities. As soon as the nanoparticles are dispersed in a resin, the viscosity dizzily rises and usually, the traditional manufacturing processes are not suitable to obtain a good quality of the manufactured panels. An alternative method has been developed starting from the Resin Film Infusion (RFI) process. This method has been firstly tested on several flat panels, and then it has been transferred on a more complex shaped panel with three stringers. In this work, a flame resistant resin based on a tetrafunctional epoxy precursor filled with carbon nanotubes to increase electrical conductivity, has been used for the panel manufacturing.

  18. CESAR at Poker Flat

    NASA Astrophysics Data System (ADS)

    Matsiev, D.; Slanger, T. G.; Hedin, J.

    2015-12-01

    The Compact Echelle Spectrograph for Aeronomic Research (CESAR) has been sited at Poker Flat Research Range since November 2013, collecting data over two seasons of the nightglow and the aurora. CESAR has operated with a field of view of seven degrees in the zenith direction, with a resolution of 5000, although a resolution three times greater is available. So far, data collection times have been in the range of 20 minutes, while the wavelength range used has been 500-1050 nm. Detailed studies of a number of optical features have been carried out. 1) It is demonstrated that the v = 2 level of the O2(b) state is best studied by using the weak b-X 2-1 band near 697 nm, it being free of auroral contamination. 2) Similarly, the best uncontaminated feature of the N2+ Meinel system is the complex A-X 0-1 band, which has been accurately simulated for the first time [Dubowsky and McCall, private communication, 2014]. 3) The N(2P-2D) quartet of lines near 1040 nm is an important auroral feature, being the N-atom equivalent of the oxygen green line. These lines are uncontaminated in many of our spectra. For lower altitude auroral excitation, there may be some overlap with the N2 First Positive 0-0 band [Pendleton et al, 1989]. 4) Time series on the O+(2P-2D) lines near 732-733 nm have been studied, showing variable background emission in this region depending on auroral type. Information on OH Meinel band lines is available throughout the region studied, and there is substantial evidence from sky spectra (Keck, VLT) that the attempt to extract kinetic temperatures from OH intensity distributions is strongly influenced by non-LTE effects [Cosby and Slanger, 2007; Noll et al, 2014].

  19. Make Your Own Solar Panel.

    ERIC Educational Resources Information Center

    Suzuki, David

    1992-01-01

    Presents an activity in which students make a simulated solar panel to learn about the principles behind energy production using solar panels. Provides information about how solar panels function to produce energy. (MCO)

  20. Flats: Preliminary WFC Data and Plans for Flight Flats

    NASA Astrophysics Data System (ADS)

    Bohlin, R. C.; Hartig, G.; Tsvetanov, Z.

    2000-10-01

    The ACS WFC pixel-to-pixel P-flats with the build-3 detector repeat over a three month time span to a precision of better than 0.1% rms. The shape of the low frequency Lflat field varies with wavelength, where the ratio of the F435W/F814W L-flats differs from unity by - 10% in two patches near opposite corners of the field of view. At ~0.5%, the high frequency pixel-to-pixel structure in the WFC P-flats is about half that of the HRC build-2 and does not increase as much toward shorter wavelengths as the HRC build-2 with the Lesser coating. The amplitude of the fringes for continuum illumination is less than 1%, even in the narrow band ramp filters, while the fringing in monochromatic light is - 10% at 9300 Å. The goals of the laboratory WFC and HRC flat field program are to obtain the set of external flats that fully populates the pipeline database and to archive a baseline of high S/N internal flats for tracking post-launch changes.