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Sample records for active matrix flat-panel

  1. An asynchronous, pipelined, electronic acquisition system for Active Matrix Flat-Panel Imagers (AMFPIs)

    The development of a full-custom electronic acquisition system designed for readout of large-area active matrix flat-panel imaging arrays is reported. The arrays, which comprise two-dimensional matrices of pixels utilizing amorphous silicon thin-film transistors, are themselves under development for a wide variety of X-ray imaging applications. The acquisition system was specifically designed to facilitate detailed, quantitative investigations of the properties of these novel imaging arrays and contains significant enhancements compared to a previously developed acquisition system. These enhancements include pipelined preamplifier circuits to allow faster readout speed, expanded addressing capabilities allowing a maximum of 4096 array data lines, and on-board summing of image frames. The values of many acquisition system parameters, including timings and voltages, may be specified and downloaded from a host computer. Once acquisition is enabled, the system operates asynchronously of its host computer. The system allows image capture in both radiographic mode (corresponding to the capture of individual X-ray images), and fluoroscopic mode (corresponding to the capture of a continual series of X-ray images). A detailed description of the system architecture and the underlying motivations for the design is reported in this paper. (author)

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

    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. Publisher's note: The title was changed from: 'Signal behavior of polycrystalline HgI2 at diagnostic energies of prototype, direct detection, active matrix, flat-panel imagers' to 'Investigation of the signal behavior at diagnostic energies of prototype, direct detection, active matrix, flat-panel imagers incorporating polycrystalline HgI2' 24 hours after initial publication to correct a mistake

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

    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. PMID:11797959

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

    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 512x512 pixels incorporating amorphous silicon photodiodes and thin-film transistors offering a 26x26 cm2 active area at a pixel pitch of 508 μm. 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

  5. Design and performance of a low noise, 128-channel ASIC preamplifier for readout of active matrix flat-panel imaging arrays

    Maolinbay, M; Yarema, R J; Antonuk, L E; El-Mohri, Y; Yeakey, M

    2002-01-01

    Design architecture and performance measurements of a low noise, 128-channel application-specific-integrated-circuit (ASIC) preamplifier are reported. The ASIC was designed for readout of active matrix flat-panel imager (AMFPI) arrays. Such arrays, which presently can be made as large as 41 cmx41 cm and with pixel-to-pixel pitches down to approx 70 mu m, require large numbers of low noise, high density, custom integrated readout circuits. The design of this new chip is specifically tailored for research and development of active matrix flat-panel arrays for various medical imaging applications. The design architecture includes the following features: (1) Programmable signal gain which allows acquisition of a wide range of signal sizes from various array designs so as to optimize the signal-to-noise ratio; (2) Correlated double sampling (CDS) which significantly reduces certain noise components; (3) Pipelined readout (simultaneously sampling and multiplexing signals) which reduces image acquisition time; (4) P...

  6. Initial performance evaluation of an indirect-detection, active matrix flat-panel imager (AMFPI) prototype for megavoltage imaging

    Purpose: The development of the first prototype active matrix flat-panel imager (AMFPI) capable of radiographic and fluoroscopic megavoltage operation is reported. The signal and noise performance of individual pixels is empirically quantified. Results of an observer-dependent study of imaging performance, using a contrast-detail phantom, are detailed and radiographic patient images are shown. Finally, a theoretical investigation of the zero-frequency detective quantum efficiency (DQE) performance of such imagers, using a cascaded systems formalism, is presented. Methods and Materials: The imager is based on a 508-μm pitch, 26 x 26 cm2 array which detects radiation indirectly via an overlying copper plate + phosphor screen converter. Results: Due to its excellent optical coupling, the imager exhibits sensitivity superior to that of video-based systems. With an ∼133 mg/cm2 Gd2O2S:Tb screen the system is x-ray quantum-noise-limited down to ∼0.3 cGy, conservatively, and extensions of this behavior to even lower doses by means of reduced additive electronic noise is predicted. The observer-dependent study indicates performance superior to that of conventional radiotherapy film while the patient images demonstrate good image quality at 1 to 4 MU. The theoretical studies suggest that, with a 133 mg/cm2 Gd2O2S:Tb screen, the system would provide DQE performance equivalent to that of video-based systems and that almost a factor of two improvement in DQE is achievable through the incorporation of a 400 mg/cm2 screen. Conclusion: The reported prototype imager is the first megavoltage AMFPI having performance characteristics consistent with practical clinical operation. The superior contrast-detail sensitivity of the imager allows the capture of high-quality 6- and 15-MV images at minimal dose. Moreover, significant performance improvements, including extension of the operational range up to full portal doses, appear feasible. Such capabilities could be of considerable

  7. Design and performance of a low noise, 128-channel ASIC preamplifier for readout of active matrix flat-panel imaging arrays

    Design architecture and performance measurements of a low noise, 128-channel application-specific-integrated-circuit (ASIC) preamplifier are reported. The ASIC was designed for readout of active matrix flat-panel imager (AMFPI) arrays. Such arrays, which presently can be made as large as 41 cmx41 cm and with pixel-to-pixel pitches down to ∼70 μm, require large numbers of low noise, high density, custom integrated readout circuits. The design of this new chip is specifically tailored for research and development of active matrix flat-panel arrays for various medical imaging applications. The design architecture includes the following features: (1) Programmable signal gain which allows acquisition of a wide range of signal sizes from various array designs so as to optimize the signal-to-noise ratio; (2) Correlated double sampling (CDS) which significantly reduces certain noise components; (3) Pipelined readout (simultaneously sampling and multiplexing signals) which reduces image acquisition time; (4) Programmable bandwidth controls which balance noise and acquisition speed; and (5) Two selectable modes of output multiplexing (64:1, 16:1) for slow or fast readout. In this paper, detailed measurements of various performance parameters are presented. These measurements include noise characteristics, the relationship between bandwidth and noise, signal response linearity, channel-to-channel and pipeline cross-talk, signal gain and gain variation across channels, and the effect of sampling methods on noise. These characterizations indicate that the performance of the ASIC has achieved the original design goals

  8. Empirical and theoretical investigation of the noise performance of indirect detection, active matrix flat-panel imagers (AMFPIs) for diagnostic radiology.

    Siewerdsen, J H; Antonuk, L E; el-Mohri, Y; Yorkston, J; Huang, W; Boudry, J M; Cunningham, I A

    1997-01-01

    Noise properties of active matrix, flat-panel imagers under conditions relevant to diagnostic radiology are investigated. These studies focus on imagers based upon arrays with pixels incorporating a discrete photodiode coupled to a thin-film transistor, both fabricated from hydrogenated amorphous silicon. These optically sensitive arrays are operated with an overlying x-ray converter to allow indirect detection of incident x rays. External electronics, including gate driver circuits and preamplification circuits, are also required to operate the arrays. A theoretical model describing the signal and noise transfer properties of the imagers under conditions relevant to diagnostic radiography, fluoroscopy, and mammography is developed. This frequency-dependent model is based upon a cascaded systems analysis wherein the imager is conceptually divided into a series of stages having intrinsic gain and spreading properties. Predictions from the model are compared with x-ray sensitivity and noise measurements obtained from individual pixels from an imager with a pixel format of 1536 x 1920 pixels at a pixel pitch of 127 microns. The model is shown to be in excellent agreement with measurements obtained with diagnostic x rays using various phosphor screens. The model is used to explore the potential performance of existing and hypothetical imagers for application in radiography, fluoroscopy, and mammography as a function of exposure, additive noise, and fill factor. These theoretical predictions suggest that imagers of this general design incorporating a CsI: Tl intensifying screen can be optimized to provide detective quantum efficiency (DQE) superior to existing screen-film and storage phosphor systems for general radiography and mammography. For fluoroscopy, the model predicts that with further optimization of a-Si:H imagers, DQE performance approaching that of the best x-ray image intensifier systems may be possible. The results of this analysis suggest strategies for

  9. An investigation of signal performance enhancements achieved through innovative pixel design across several generations of indirect detection, active matrix, flat-panel arrays

    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

  10. Flat panel display - Impurity doping technology for flat panel displays

    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

  11. Flat panel display - Impurity doping technology for flat panel displays

    Suzuki, Toshiharu [Advanced Technology Planning, Sumitomo Eaton Nova Corporation, SBS Tower 9F, 10-1, Yoga 4-chome, Setagaya-ku, 158-0097 Tokyo (Japan)]. E-mail: suzuki_tsh@senova.co.jp

    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.

  12. Display elements and gaps: a comparison of flat panel display characteristics

    Spenkelink, G.P.J.; Besuijen, J.

    1992-01-01

    The relation between typical flat panel display characteristics and display quality was studied. Subjective preferences were obtained with respect to simulated black-on-white flat panel displays. The displays differed in the sort of separation between the display elements and the shape of these elements. Further, the height/width ratio of the front was studied in relation with a fixed font matrix. The preferences were obtained through a paired comparison of all possible pairs of simulated dis...

  13. Design scenarios for flat panel photobioreactors

    Slegers, P.M.; Wijffels, R.H.; Straten, van G.; Boxtel, van A.J.B.

    2011-01-01

    Evaluation of the potential of algae production for biofuel and other products at various locations throughout the world requires assessment of algae productivity under varying light conditions and different reactor layouts. A model was developed to predict algae biomass production in flat panel pho

  14. 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?

    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. (orig.)

  15. Digital radiography with large-area flat-panel detectors

    Kotter, E.; Langer, M. [Department of Diagnostic Radiology, Freiburg University Hospital, Hugstetterstrasse 55, 79106 Freiburg (Germany)

    2002-10-01

    Large-area flat-panel detectors with active readout mechanisms have been on the market for the past 2 years. This article describes different detector technologies. An important distinction is made between detectors with direct and those with indirect conversion of X-rays into electrical charges. Detectors with indirect conversion are built with unstructured or structured scintillators, the latter resulting in less lateral diffusion of emitted light. Some important qualities of flat-panel detectors are discussed. The first phantom and clinical studies published report an image quality at least comparable to that of screen-film systems and a potential for dose reduction. The available studies are summarised in this article. (orig.)

  16. Digital radiography with large-area flat-panel detectors

    Large-area flat-panel detectors with active readout mechanisms have been on the market for the past 2 years. This article describes different detector technologies. An important distinction is made between detectors with direct and those with indirect conversion of X-rays into electrical charges. Detectors with indirect conversion are built with unstructured or structured scintillators, the latter resulting in less lateral diffusion of emitted light. Some important qualities of flat-panel detectors are discussed. The first phantom and clinical studies published report an image quality at least comparable to that of screen-film systems and a potential for dose reduction. The available studies are summarised in this article. (orig.)

  17. Design scenarios for flat panel photobioreactors

    Evaluation of the potential of algae production for biofuel and other products at various locations throughout the world requires assessment of algae productivity under varying light conditions and different reactor layouts. A model was developed to predict algae biomass production in flat panel photobioreactors using the interaction between light and algae growth for the algae species Phaeodactylum tricornutum and Thalassiosira pseudonana. The effect of location, variable sunlight and reactor layout on biomass production in single standing and parallel positioned flat panels was considered. Three latitudes were studied representing the Netherlands, France and Algeria. In single standing reactors the highest yearly biomass production is achieved in Algeria. During the year biomass production fluctuates the most in the Netherlands, while it is almost constant in Algeria. Several combinations of path lengths and biomass concentrations can result in the same optimal biomass production. The productivity in parallel place flat panels is strongly influenced by shading and diffuse light penetration between the panels. Panel orientation has a large effect on productivity and at higher latitudes the difference between north-south and east-west orientation may go up to 50%.

  18. Ultrabarrier Flexible Substrates for Flat Panel Displays

    Burrows, Paul E.; Graff, Gordon L.; Gross, Mark E.; Martin, Peter M.; Shi, Ming-Kun; Hall, Michael G.; Mast, Eric S.; Bonham, Charles C.; Bennett, Wendy D.; Sullivan, Michael B.

    2001-05-01

    We describe a flexible, transparent plastic substrate for flat panel display applications. Using roll-coating techniques, we apply a composite thin film barrier to commercially available polymers, which restricts moisture and oxygen permeation to undetectable levels. The barrier film can be capped with a thin film of transparent conductive oxide in the same roll-coater, yielding an engineered substrate (Barix™) for next generation, rugged, lightweight or flexible displays. The substrate is sufficiently impermeable to moisture and oxygen for application to moisture-sensitive display applications, such as organic light emitting displays (OLEDs). This enables, for the first time, lightweight and flexible emissive organic displays.

  19. Development of flat panel digital radiography system

    We developed the Digital Radiography System CXDI-11 which digitizes the X-ray image in high quality by using a self-developed flat panel detector. The CXDI-11 has a large image area of 43 cm x 43 cm (17'' x 17''), and it can display the image on the pre-view monitor after only 3 seconds of exposure. In this report, we present the principle and the physical characteristics of the CXDI-11. The X-ray detector installed in the CXDI-11 is a combination of a rare-earth scintillator and an amorphous silicon flat panel detector (LANMIT). The X-ray is converted to the visible fluorescent light at the scintillator and the light is detected by the LANMIT. The image-processed data is transferred to the DICOM3.0 conformed devices such as the diagnosis work station, the archiver and the laser imager through the network. We also show some measurement results of the dynamic range, the pre-sampling Modulation Transfer Function and the tube voltage dependent sensitivity. The CXDI-11 is superior in real time operation and image quality, thus it is the digital radiography system of the next generation. (author)

  20. Treatment field specific IMRT QA using flat panel

    Electronic portal imaging devices are commonly used for geometric verification of patient positioning during the treatment. However their use has been increasingly extended in extracting dosimetric information of the radiation treatment. To extend the use of flat panel for dosimetric purposes few characteristics of the flat panel like reproducibility, temporal stability, ghosting effect, dose-response relationship have to be studied. This work presents the use of flat panel for the relative verification of individual treatment field fluence for IMRT

  1. Evaluation of flat panel PMT for gamma ray imaging

    The first position sensitive PMT, Hamamatsu R2486, developed in 1985, represented a strong technological advance for gamma-ray imaging. Hamamatsu H8500 Flat Panel PMT is the last generation position sensitive PMT: extremely compact with 2 in. active area. Its main features are: minimum peripheral dead zone (1 mm) and height of 12 mm. It was designed to be assembled in array to cover large detection area. It can represent a technical revolution for many applications in the field of gamma-ray imaging as for example nuclear medicine. This tube is based on metal channel dynode for charge multiplication and 8x8 anodes for charge collection and position calculation. In this paper we present a preliminary evaluation of the imaging performances addressed to nuclear medicine application. To this aim we have taken into account two different electronic readouts: resistive chain with Anger Camera principle and multianode readout. Flat panel PMT was coupled to CsI(Tl) and NaI(Tl) scintillation arrays. The results were also compared with the first generation PSPMT

  2. The Dexela 2923 CMOS X-ray detector: A flat panel detector based on CMOS active pixel sensors for medical imaging applications

    Konstantinidis, A. C.; Szafraniec, M. B.; Speller, R.D.; Olivo, A.

    2012-01-01

    Complementary metal-oxide-semiconductors (CMOS) active pixel sensors (APS) have been introduced recently in many scientific applications. This work reports on the performance (in terms of signal and noise transfer) of an X-ray detector that uses a novel CMOS APS which was developed for medical X-ray imaging applications. For a full evaluation of the detector's performance, electro-optical and X-ray characterizations were carried out. The former included measuring read noise, full well capacit...

  3. The Dexela 2923 CMOS X-ray detector: A flat panel detector based on CMOS active pixel sensors for medical imaging applications

    Complementary metal-oxide-semiconductors (CMOS) active pixel sensors (APS) have been introduced recently in many scientific applications. This work reports on the performance (in terms of signal and noise transfer) of an X-ray detector that uses a novel CMOS APS which was developed for medical X-ray imaging applications. For a full evaluation of the detector's performance, electro-optical and X-ray characterizations were carried out. The former included measuring read noise, full well capacity and dynamic range. The latter, which included measuring X-ray sensitivity, presampling modulation transfer function (pMTF), noise power spectrum (NPS) and the resulting detective quantum efficiency (DQE), was assessed under three beam qualities (28 kV, 50 kV (RQA3) and 70 kV (RQA5) using W/Al) all in accordance with the IEC standard. The detector features an in-pixel option for switching the full well capacity between two distinct modes, high full well (HFW) and low full well (LFW). Two structured CsI:Tl scintillators of different thickness (a “thin” one for high resolution and a thicker one for high light efficiency) were optically coupled to the sensor array to optimize the performance of the system for different medical applications. The electro-optical performance evaluation of the sensor results in relatively high read noise (∼360 e−), high full well capacity (∼1.5×106 e−) and wide dynamic range (∼73 dB) under HFW mode operation. When the LFW mode is used, the read noise is lower (∼165) at the expense of a reduced full well capacity (∼0.5×106 e−) and dynamic range (∼69 dB). The maximum DQE values at low frequencies (i.e. 0.5 lp/mm) are high for both HFW (0.69 for 28 kV, 0.71 for 50 kV and 0.75 for 70 kV) and LFW (0.69 for 28 kV and 0.7 for 50 kV) modes. The X-ray performance of the studied detector compares well to that of other mammography and general radiography systems, obtained under similar experimental conditions. This demonstrates the

  4. Flat-panel detectors in x-ray diagnosis

    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. (orig.)

  5. Electroluminescent Polymers and Carbon Nanotubes for Flat Panel Displays

    Liming Dai; Limin Dong; Mei Gao; Shaoming Huang; Oddvar Johansen; Albert W.H.Mau,Zoran Vasic; Berthold Winkler; Yongyuang Yang

    2000-01-01

    polymeric light-emitting diodes(LEDs) with sufficient brightness. efficiencies, low driving voltages, and various interesting features have been reported. The relatively short device lifetime, however, still remains as a major problem to be solved before any commercial applications will be realized. In this regard,carbon nanotubes have recently been proposed as more robust electron field emitters for flat panel displays. We have synthesised large arrays of vertically aligned carbon nanotubes, from which micropatterns of the aligned nanotubes suitable for flat panel displays were fabricated on various substrates. In this paper, we summarise our work on the synthesis and microfabrication of electroluminescent polymers and carbon nanotubes for flat panel displays with reference to other complementary work as appropriate.

  6. Flat panel computed tomography of human ex vivo heart and bone specimens: initial experience

    Nikolaou, Konstantin; Becker, Christoph R.; Reiser, Maximilian F. [Ludwig-Maximilians-University, Department of Clinical Radiology, Munich (Germany); Flohr, Thomas; Stierstorfer, Karl [CT Division, Siemens Medical Solutions, Forchheim (Germany)

    2005-02-01

    The aim of this technical investigation was the detailed description of a prototype flat panel detector computed tomography system (FPCT) and its initial evaluation in an ex vivo setting. The prototype FPCT scanner consists of a conventional radiographic flat panel detector, mounted on a multi-slice CT scanner gantry. Explanted human ex vivo heart and foot specimens were examined. Images were reformatted with various reconstruction algorithms and were evaluated for high-resolution anatomic information. For comparison purposes, the ex vivo specimens were also scanned with a conventional 16-detector-row CT scanner (Sensation 16, Siemens Medical Solutions, Forchheim, Germany). With the FPCT prototype used, a 1,024 x 768 resolution matrix can be obtained, resulting in an isotropic voxel size of 0.25 x 0.25 x 0.25 mm at the iso-center. Due to the high spatial resolution, very small structures such as trabecular bone or third-degree, distal branches of coronary arteries could be visualized. This first evaluation showed that flat panel detector systems can be used in a cone-beam computed tomography scanner and that very high spatial resolutions can be achieved. However, there are limitations for in vivo use due to constraints in low contrast resolution and slow scan speed. (orig.)

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

    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. PMID:20123746

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

    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. PMID:18374710

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

    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

  10. Synchrotron applications of an amorphous silicon flat-panel detector

    A GE Revolution 41RT flat-panel detector (GE 41RT) from GE Healthcare (GE) has been in operation at the Advanced Photon Source for over two years. The detector has an active area of 41 cm x 41 cm with 200 (micro)m x 200 (micro)m pixel size. The nominal working photon energy is around 80 keV. The physical set-up and utility software of the detector system are discussed in this article. The linearity of the detector response was measured at 80.7 keV. The memory effect of the detector element, called lag, was also measured at different exposure times and gain settings. The modulation transfer function was measured in terms of the line-spread function using a 25 (micro)m x 1 cm tungsten slit. The background (dark) signal, the signal that the detector will carry without exposure to X-rays, was measured at three different gain settings and with exposure times of 1 ms to 15 s. The radial geometric flatness of the sensor panel was measured using the diffraction pattern from a CeO2 powder standard. The large active area and fast data-capturing rate, i.e. 8 frames s-1 in radiography mode, 30 frames s-1 in fluoroscopy mode, make the GE 41RT one of a kind and very versatile in synchrotron diffraction. The loading behavior of a Cu/Nb multilayer material is used to demonstrate the use of the detector in a strain-stress experiment. Data from the measurement of various samples, amorphous SiO2 in particular, are presented to show the detector effectiveness in pair distribution function measurements

  11. Evaluation of stent visibility by flat panel detector CT in patients treated for intracranial aneurysms

    Clarencon, Frederic [Groupe Hospitalier Pitie-Salpetriere, Paris (France); Pitie-Salpetriere Hospital, Department of Neuroradiology, Paris (France); Piotin, Michel; Pistocchi, Silvia; Blanc, Raphael [Fondation A. de Rothschild, Paris (France); Babic, Drazenko [Philips Healthcare, Best (Netherlands)

    2012-10-15

    This study aimed to evaluate the visibility of stents using high-resolution computed tomography (CT) acquisitions acquired with flat panel detector (XperCT, Allura series, Philips Healthcare, The Netherlands) for endovascular treatment of intracranial aneurysms. On a 24-month period, 48 patients endovascularly treated by coiling and stenting (59 stents) for intracranial aneurysms were explored by flat panel detector CT technique. A sequence of 620 2D images was acquired over an angle of 240 using a 1,024 x 1,024 pixel matrix detector within a 48-cm field of view. The images were retrospectively analyzed independently by two neuroradiologists. Evaluation criteria were percentage of visualization of the stents and stent deployment (kinking or unsatisfactory deployment of the stent). Evaluation of the stent was feasible for all the patients. Stent visibility by XperCT was overall estimated at 76% of the stent length. Difficulties to analyze the stents were related to coil artifacts but not to packing density or aneurysm location. Stent length visualization was higher when the acquisition was performed before additional coiling (P < 0.0001). Mild kinking/misdeployment was noticed in 22% of the cases. XperCT technique provides multiplanar and 3D reconstructions that allows for a satisfying visualization of intracranial stents. This CT-like acquisition should be performed after the stent deployment and before coiling, in order to obtain better stent visualization. (orig.)

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

    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.

  13. Standard practice for radiologic examination of flat panel composites and sandwich core materials used in aerospace applications

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 This practice is intended to be used as a supplement to Practices E 1742, E 1255, and E 2033. 1.2 This practice describes procedures for radiologic examination of flat panel composites and sandwich core materials made entirely or in part from fiber-reinforced polymer matrix composites. Radiologic examination is: a) radiographic (RT) with film, b) Computed Radiography (CR) with Imaging Plate, c) Digital Radiology (DR) with Digital Detector Array’s (DDA), and d) Radioscopic (RTR) Real Time Radiology with a detection system such as an Image Intensifier. The composite materials under consideration typically contain continuous high modulus fibers (> 20 GPa), such as those listed in 1.4. 1.3 This practice describes established radiological examination methods that are currently used by industry that have demonstrated utility in quality assurance of flat panel composites and sandwich core materials during product process design and optimization, process control, after manufacture inspection, in service exami...

  14. System performance of a prototype flat-panel imager operated under mammographic conditions

    The results of an empirical and theoretical investigation of the performance of a high-resolution, active matrix flat-panel imager performed under mammographic conditions are reported. The imager is based upon a prototype, indirect detection active matrix array incorporating a discrete photodiode in each pixel and a pixel-to-pixel pitch of 97 μm. The investigation involved three imager configurations corresponding to the use of three different x-ray converters with the array. The converters were a conventional Gd2O2S-based mammographic phosphor screen (Min-R) and two structured CsI:Tl scintillators: one optimized for high spatial resolution (FOS-HR) and the other for high light output (FOS-HL). Detective quantum efficiency for mammographic exposures ranging from ∼2 to ∼40 mR at 26 kVp were determined for each imager configuration through measurements of x-ray sensitivity, modulation transfer function (MTF), and noise power spectrum (NPS). All configurations were found to provide significant presampling MTF at frequencies beyond the Nyquist frequency of the array, ∼5.2 mm-1, consistent with the high spatial resolution of the converters. In addition, the effect of additive electronic noise on the NPS was found to be significantly larger for the configuration with lower system gain (FOS-HR) than for the configurations with higher gain (Min-R, FOS-HL). The maximum DQE values obtained with the CsI:Tl scintillators were considerably greater than those obtained with the Min-R screen due to the significantly lower Swank noise of the scintillators. Moreover, DQE performance was found to degrade with decreasing exposure, although this exposure-dependence was considerably reduced for the higher gain configurations. Theoretical calculations based on the cascaded systems model were found to be in generally good agreement with these empirically determined NPS and DQE values. In this study, we provide an example of how cascaded systems modeling can be used to identify

  15. System performance of a prototype flat-panel imager operated under mammographic conditions.

    Jee, Kyung-Wook; Antonuk, Larry E; El-Mohri, Youcef; Zhao, Qihua

    2003-07-01

    The results of an empirical and theoretical investigation of the performance of a high-resolution, active matrix flat-panel imager performed under mammographic conditions are reported. The imager is based upon a prototype, indirect detection active matrix array incorporating a discrete photodiode in each pixel and a pixel-to-pixel pitch of 97 microm. The investigation involved three imager configurations corresponding to the use of three different x-ray converters with the array. The converters were a conventional Gd2O2S-based mammographic phosphor screen (Min-R) and two structured CsI:Tl scintillators: one optimized for high spatial resolution (FOS-HR) and the other for high light output (FOS-HL). Detective quantum efficiency for mammographic exposures ranging from approximately 2 to approximately 40 mR at 26 kVp were determined for each imager configuration through measurements of x-ray sensitivity, modulation transfer function (MTF), and noise power spectrum (NPS). All configurations were found to provide significant presampling MTF at frequencies beyond the Nyquist frequency of the array, approximately 5.2 mm(-1) , consistent with the high spatial resolution of the converters. In addition, the effect of additive electronic noise on the NPS was found to be significantly larger for the configuration with lower system gain (FOS-HR) than for the configurations with higher gain (Min-R, FOS-HL). The maximum DQE values obtained with the CsI:Tl scintillators were considerably greater than those obtained with the Min-R screen due to the significantly lower Swank noise of the scintillators. Moreover, DQE performance was found to degrade with decreasing exposure, although this exposure-dependence was considerably reduced for the higher gain configurations. Theoretical calculations based on the cascaded systems model were found to be in generally good agreement with these empirically determined NPS and DQE values. In this study, we provide an example of how cascaded

  16. EMI investigation and modeling of a flat panel display

    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

  17. Quantitative digital radiography with two dimensional flat panels

    Purpose: Attenuation law relates radiographic images to irradiated object thickness and chemical composition. Film radiography exploits qualitatively this property for diagnosis. Digital radiographic flat panels present large dynamic range, reproducibility and linearity properties which open the gate for quantification. We will present, through two applications (mammography and bone densitometry), an approach to extract quantitative information from digital 2D radiographs. Material and method: The main difficulty for quantification is X-rays scatter, which superimposes to acquisition data. Because of multiple scatterings and 3D geometry dependence, it cannot be directly exploited through an exact analytical model. Therefore we have developed an approach for its estimation and subtraction from medical radiographs, based on approximations and derivations of analytical models of scatter formation in human tissues. Results: In digital mammography, the objective is to build a map of the glandular tissue thickness. Its separation from fat tissue is based on two equations: height of compression and attenuation. This last equation needs X-Rays scatter correction. In bone densitometry, physicians look for quantitative bone mineral density. Today, clinical DEXA systems use collimated single or linear detectors to eliminate scatter. This scanning technology induces poor image quality. By applying our scatter correction approach, we have developed a bone densitometer using a digital flat panel (Lexxos, DMS). It provides with accurate and reproducible measurements while presenting radiological image quality. Conclusion: These applications show how information processing, and especially X-Rays scatter processing, enables to extract quantitative information from digital radiographs. This approach, associated to Computer Aided Diagnosis algorithms or reconstructions algorithms, gives access to useful information for diagnosis. (author)

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

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

    2003-12-21

    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 x 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:T1 (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 x 100 x 200 microm3 and the air kerma of 286 mGy. When the magnification ratio is 2, the spatial resolution of the micro-CT system is about 14 1p/mm (line pairs per millimetre) that is almost determined by the flat-panel detector showing about 7 1p/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. PMID:14727760

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

    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 x 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 x 100 x 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

  20. Comparison of flat-panel radiography and computed radiography in urography

    Purpose: To evaluate the diagnostic value of digital flat-panel radiography in uro-radiology the i.v. urograms of patients who had been examined with computed radiography and digital flat-panel radiography were compared regarding image quality. Methods: 50 patients who underwent clinically indicated i.v. urography were examined with digital flat-panel radiography and computed radiography. In order to avoid unnecessary double exposure to X-rays, patients were examined either by flat-panel or computed radiography before injection of contrast media. Each further clinically indicated exposure after administration of contrast media was done by alternating the other examination technique. The digital images were compared by 4 radiologists regarding image quality for the detection of defined anatomic structures. Results: Digital flat-panel radiography showed an image quality of the liver, spleen and both kidneys that was similar to computed radiography. The urinary tract, lumbar spine, pelvis and psoas muscle were significantly better visible on flat-panel radiography images. Conclusions: Compared to computed radiography there is no loss of image information by using digital flat-panel radiography in uro-radiology. On the contrary, some anatomic structures on abdominal survey images show better image quality. In conclusion, digital flat-panel radiography has the potential to replace computed radiography in uroradiologic examinations. (orig.)

  1. 75 FR 51286 - Certain Flat Panel Digital Televisions and Components Thereof; Notice of Investigation

    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... mobility impairments who will need special assistance in gaining access to the Commission should...

  2. Sarnoff JND Vision Model for Flat-Panel Design

    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,

  3. Characteristics and applications of a flat panel computer tomography system

    Purpose: to assess a new flat panel volume computed tomography (FP-VCT) with very high isotropic spatial resolution as well as high Z-axis coverage. Materials and Methods: The prototype of an FP-VCT scanner with a detector cell size of 0.2 mm was used for numerous phantom studies, specimen examinations, and animal research projects. Results: The high spatial resolution of the new system can be used to accurately determine solid tumor volume, thus allowing for earlier assessment of the therapeutic response. In animal experimentation, whole-body perfusion mapping of mice is feasible. The high spatial resolution also improves the classification of coronary artery atherosclerotic plaques in the isolated post mortem human heart. With the depiction of intramyocardial segments of the coronary arteries, investigations of myocardial collateral circulation are feasible. In skeletal applications, an accurate analysis of the smallest bony structures, e.g., petrous bone and dental preparations, can be successfully performed, as well as investigations of repetitive studies of fracture healing and the treatment of osteoporosis. Conclusion: The introduction of FP-VCT opens up new applications for CT, including the field of molecular imaging, which are highly attractive for future clinical applications. Present limitations include limited temporal resolution and necessitate further improvement of the system. (orig.)

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

    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.

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

    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 ex...

  6. Flat-panel detectors: how much better are they?

    Interventional and fluoroscopic imaging procedures for pediatric patients are becoming more prevalent because of the less-invasive nature of these procedures compared to alternatives such as surgery. Flat-panel X-ray detectors (FPD) for fluoroscopy are a new technology alternative to the image intensifier/TV (II/TV) digital system that has been in use for more than two decades. Two major FPD technologies have been implemented, based on indirect conversion of X-rays to light (using an X-ray scintillator) and then to proportional charge (using a photodiode), or direct conversion of X-rays into charge (using a semiconductor material) for signal acquisition and digitization. These detectors have proved very successful for high-exposure interventional procedures but lack the image quality of the II/TV system at the lowest exposure levels common in fluoroscopy. The benefits for FPD image quality include lack of geometric distortion, little or no veiling glare, a uniform response across the field-of-view, and improved ergonomics with better patient access. Better detective quantum efficiency indicates the possibility of reducing the patient dose in accordance with ALARA principles. However, first-generation FPD devices have been implemented with less than adequate acquisition flexibility (e.g., lack of tableside controls/information, inability to easily change protocols) and the presence of residual signals from previous exposures, and additional cost of equipment and long-term maintenance have been serious impediments to purchase and implementation. Technological advances of second generation and future hybrid FPD systems should solve many current issues. The answer to the question ''how much better are they?'' is ''significantly better'', and they are certainly worth consideration for replacement or new implementation of an imaging suite for pediatric fluoroscopy. (orig.)

  7. Performance of a volumetric CT scanner based upon a flat-panel imager

    Jaffray, David A.; Siewerdsen, Jeffrey H.; Drake, Douglas G.

    1999-05-01

    To characterize the performance of a cone-beam computed tomography (CBCT) imaging system based upon an indirect- detection, amorphous silicon flat-panel imager (FPI). Tomographic images obtained using the FPI are presented, and the signal and noise characteristics of reconstructed images are quantified. Specifically, the spatial uniformity, CT linearity, contrast performance, noise characteristics, spatial resolution, and soft-tissue visualization are examined. Finally, the performance of the FPI-based CT system is discussed in relation to existing clinical technologies. A table-top measurements system was constructed to allow investigation of FPI performance in CBCT within a precisely controlled and reproducible geometry. The FPI incorporates a 512 X 512 active matrix array of a-Si:H thin-film transistors and photodiodes in combination with an overlying (133 mg/cm2 Gd2O2S:Tb) phosphor. The commercially available prototype FPI has a pixel pitch of 400 micrometer, a fill factor of approximately 80%, can be read at a maximum frame rate of 5 fps, and provides 16 bit digitization. Mounted upon an optical bench are the x-ray tube (in a rigid support frame), the object to be imaged (upon a precision rotation/translation table), and the FPI (mounted upon a precision translation table). The entire setup is directed under computer control, and volumetric imaging is accomplished by rotating the object incrementally over 360 degrees, delivering a radiographic x-ray pulse (e.g., 100 - 130 kVp, approximately 0.1 - 10 mAs), and acquiring a projection image at each increment. Prior to reconstruction, dark and flood- field corrections are applied to account for stationary nonuniformities in detector response and dark current. Tomographic images are reconstructed from the projections using the Feldkamp filtered back-projection algorithm for CBCT. The linearity of the CBCT system was compared to that of a commercial scanner (Philips SR-7000) using materials ranging in CT number from

  8. Optimization of the presampling modulation transfer function of flat-panel detectors for digital radiology

    Rowlands, John A.; Ji, Winston G.

    1999-05-01

    Large area, flat panel solid state detectors are being investigated for digital radiography and fluoroscopy. These detectors employ an x-ray imaging layer of either photoconductor ('direct' conversion method) or phosphor ('indirect' conversion method) to detect x-rays. In both cases the image formed at the surface of the layer is read out in situ using an active matrix array. Depending upon the resolution of the layer compared to the pixel size, undersampling of the image and hence aliasing may occur. Aliasing is always present regardless of the pixel size in direct detectors based on amorphous selenium because of its high intrinsic resolution. Aliasing gives rise to increased noise which results in reduction of detective quantum efficiency DQE at high spatial frequencies. The aliasing can be reduced or even eliminated by blurring prior to pixel sampling (e.g., by scattering in a phosphor layer). However, blurring, which may be quantified by the spatial frequency f dependent modulation transfer function MTF(f), also has a deleterious effect: the imaging system becomes much more susceptible to noise for example that arising in the charge amplifiers or secondary quantum statistics. Note that in principle, the system MTF can be corrected to any desired values in a digital system thus MTF has no predictive value for the quality of an imaging system, rather it is the DQE(f) which determines the overall signal to noise ratio independently of the MTF enhancement chosen. Nevertheless, determining the ideal level of presampling blurring (i.e., the Presampling Modulation Transfer function) is not straightforward. A problem caused by blurring is that the degree of blurring often depends on the depth of absorption of the x-ray in the imaging layer. In such cases (as pointed out by Lubberts) additional noise is transferred to the image. The predictions of a Lubberts model will be compared with published measurements of DQE for both direct and indirect detectors. A preliminary

  9. Development of a direct-conversion-type flat-panel detector for radiography and fluoroscopy

    This paper describes the X-ray flat-panel detector technology which will be able to take the place of all conventional X-ray detector technologies. Hospitals are rapidly changing from handling information with analogue systems to using digital systems, accompanying the advances being made in this digital information age. The X-ray flat-panel detector will convert 2D distribution of X-ray intensity to digital image data instantly. Until now, there has not been an X-ray flat-panel detector that can completely take the place of analogue X-ray films with screens (S-F) and can acquire high-speed dynamic X-ray images with high image quality, but we have realized this by developing a direct-conversion-type flat-panel detector. The latest research result confirmed the increase of X-ray absorption capability, spatial resolution which exceeded a regular type of S-F and images without distortion in a large field of view. This detector is a compact size, just like an X-ray cassette, and can be used for both radiography and fluoroscopy, which can take the place not only of S-F but also Imaging Intensifier (I.I.) -TV. The X-ray flat-panel detector will cause dramatic changes to all X-ray systems and we can say specially that the direct-type flat-panel detector has proven to be a step toward the coming era of real full-digital hospitals. (author)

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

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

    2016-04-01

    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. PMID:26950078

  11. 75 FR 51285 - In the Matter of Certain Flat Panel Digital Televisions and Components Thereof; Notice of...

    2010-08-19

    ... COMMISSION In the Matter of Certain Flat Panel Digital Televisions and Components Thereof; Notice of... United States after importation of certain flat panel digital televisions and components thereof by...-1810. Persons with mobility impairments who will need special assistance in gaining access to...

  12. Implementation of a program of quality assurance of image in an imaging system of flat panel portal

    (IGRT) image-guided radiation therapy is the one in which images are used to locate the area of treatment. Modern irradiation systems are equipped with different modalities for obtaining images, such as flat panel systems, systems conebeam, tomoimagen, etc. This paper describes the start-up and the experience of a quality assurance program based on a flat panel portal Imaging System. (Author)

  13. Full dynamic resolution low lower DA-Converters for flat panel displays

    C. Saas

    2006-01-01

    Full Text Available It has been shown that stepwise charging can reduce the power dissipated in the source drivers of a flat panel display. However the solution presented only provided a dynamic resolution of 3 bits which is not sufficient for obtaining a full color resolution display. In this work a further development of the basic idea is presented. The stepwise charging is increased to 4 bits and supplemented by a current source to provide an output signal which represents an 8 bit value with sufficient accuracy. Within this work the application is an AM-OLED flat panel display, but the concept can easily be applied to other display technologies like TFT-LCD as well.

  14. Investigation of an amorphous silicon flat-panel detector for ion radiography

    Telsemeyer, Julia

    2012-01-01

    Using heavy ions in radiotherapy offers a good potential for targeted radiation of tumors and the ability to spare healthy tissue. Their characteristic interaction with matter holds the potential to employ ions for high-contrast radiographic imaging at a decreased dose in comparison to conventional X-ray imaging; however, it lacks simple detectors suitable for this purpose. In this study the performance of an amorphous silicon flat-panel detector, originally designed for photon imaging, was i...

  15. Structural deviation calibration and parameters obtaining algorithm for flat panel detector CT system

    Deviation of geometric parameter from its design value of flat panel detector computed tomography (CT) would result in image quality degradation. A structural deviation calibration and parameters obtaining algorithm based on projections was developed to improve the accuracy. The algorithm uses a simple calibration phantom and serial projections to adjust the system structure and analytically estimate the geometric CT parameters. Calculations demonstrate that the algorithm is very accurate with the error less than 0.5%, and experiments show high quality images. (authors)

  16. Competing Technologies and Industry Evolution: The Benefits of Making Mistakes in the Flat Panel Display Industry

    Eggers, J.P.

    2010-01-01

    Managers at firms facing uncertain competing technologies evolving concurrently face a complex decision set, including options to invest in one technology or other, both technologies, or to wait to invest. This study investigates the role that experience, learning and timing play in affecting the firm-level pros and cons of each of these four strategies in a technological competition situation. Using a unique data set on the evolution of the global flat panel display industry, this study offe...

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

    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.

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

    Doerfler, A.; Struffert, T.; Engelhorn, T.; Richter, C. [Abt. fuer Neuroradiologie, Universitaetsklinikum Erlangen, Friedrich-Alexander-Univ. Erlangen-Nuernberg (Germany)

    2008-10-15

    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. (orig.)

  19. Portable low-cost flat panel detectors for real-time digital radiography

    Iovea, Mihai; Neagu, Marian; Stefanescu, Bogdan; Mateiasi, Gabriela; Porosnicu, Ioana; Angheluta, Elena [Accent Pro 2000 S.R.L., Bucharest (Romania)

    2015-07-01

    The X-ray inspection is one of the most common used non-destructive testing methods in industry applications, but for the portable X-ray digital solution are not so many accessible, low-cost and versatile detection devices. The efficiency of a non-destructive X-ray portable device is represented by the quality of digital images, by its low acquisition time combined with a high resolution, in condition of low noise and at an affordable cost. The paper presents two X-ray portable imaging systems developed by us, suitable also for aerospace NDT applications, which are also very versatile for being easily adapted for other fields that requires mobile solutions. The first device described in the paper represent a portable large-size (210 mm X 550 mm) and high-resolution (27/54 microns) flat panel detector based on linear translation of a X-Ray TDI detector, destined for various components/parts real-time transmission measurements. The second system it is also a flat panel detectors, with a size of 510 mm X 610 mm, with the detector size from 0.2 mm until 1.5 mm, which can operate by applying the dual-energy method, very useful for discriminating materials by evaluating their Atomic effective number. The high resolution and low-cost of this flat-panels widens their applicability by covering large requirements, from identifying unwanted materials within a structure until detection of very thin cracks in complex components.

  20. Portable low-cost flat panel detectors for real-time digital radiography

    The X-ray inspection is one of the most common used non-destructive testing methods in industry applications, but for the portable X-ray digital solution are not so many accessible, low-cost and versatile detection devices. The efficiency of a non-destructive X-ray portable device is represented by the quality of digital images, by its low acquisition time combined with a high resolution, in condition of low noise and at an affordable cost. The paper presents two X-ray portable imaging systems developed by us, suitable also for aerospace NDT applications, which are also very versatile for being easily adapted for other fields that requires mobile solutions. The first device described in the paper represent a portable large-size (210 mm X 550 mm) and high-resolution (27/54 microns) flat panel detector based on linear translation of a X-Ray TDI detector, destined for various components/parts real-time transmission measurements. The second system it is also a flat panel detectors, with a size of 510 mm X 610 mm, with the detector size from 0.2 mm until 1.5 mm, which can operate by applying the dual-energy method, very useful for discriminating materials by evaluating their Atomic effective number. The high resolution and low-cost of this flat-panels widens their applicability by covering large requirements, from identifying unwanted materials within a structure until detection of very thin cracks in complex components.

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

    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

    2011-07-01

    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. PMID:21532584

  2. Reduction in Power Consumption for Full-Color Active Matrix Organic Light-Emitting Devices

    Kanno, Hiroshi; Hamada, Yuji; Nishimura, Kazuki; Okumoto, Kenji; Saito, Nobuo; Mameno, Kazunobu; Shibata, Kenichi

    2006-09-01

    The active matrix organic light-emitting diode (AMOLED) is expected to serve as next generation flat panels display with the outstanding features of wide viewing angle, vivid images, and quick response. For practical use of full-color AMOLEDs in mobile devices, it is essential to reduce the power consumption, which is generally higher than that of liquid crystal displays (LCDs). For this aim, a red, green, blue, and white (RGBW) pixel format combined with an RGB color filter array (RGBW format) with a common white emission layer (EML) has been developed. We find that the RGBW format can successfully reduce the power consumption of a full-color AMOLED by nearly half that of a conventionally filtered RGB pixel format. This improved power consumption is almost equal to the power consumption of a same-sized LCD. The RGBW format is a promising technique for the further reduction of the power consumption of a full-color AMOLED.

  3. Image Quality of Digital Direct Flat-Panel Mammography Versus an Indirect Small-Field CCD Technique Using a High-Contrast Phantom

    Kathrin Barbara Krug

    2011-01-01

    Full Text Available Objective. To compare the detection of microcalcifications on mammograms of an anthropomorphic breast phantom acquired by a direct digital flat-panel detector mammography system (FPM versus a stereotactic breast biopsy system utilizing CCD (charge-coupled device technology with either a 1024 or 512 acquisition matrix (1024 CCD and 512 CCD. Materials and Methods. Randomly distributed silica beads (diameter 100–1400 m and anthropomorphic scatter bodies were applied to 48 transparent films. The test specimens were radiographed on a direct digital FPM and by the indirect 1024 CCD and 512 CCD techniques. Four radiologists rated the monitor-displayed images independently of each other in random order. Results. The rate of correct positive readings for the “number of detectable microcalcifications” for silica beads of 100–199 m in diameter was 54.2%, 50.0% and 45.8% by FPM, 1024 CCD and 512 CCD, respectively. The inter-rater variability was most pronounced for silica beads of 100–199 m in diameter. The greatest agreement with the gold standard was observed for beads >400 m in diameter across all methods. Conclusion. Stereotactic spot images taken by 1024 matrix CCD technique are diagnostically equivalent to direct digital flat-panel mammograms for visualizing simulated microcalcifications >400 m in diameter.

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

    Karim S. Karim

    2011-05-01

    Full Text Available 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

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

    Seslija, Petar; Teeter, Matthew G.; Yuan Xunhua; Naudie, Douglas D. R.; Bourne, Robert B.; MacDonald, Steven J.; Peters, Terry M.; Holdsworth, David W. [Biomedical Engineering Graduate Program, University of Western Ontario, London, Ontario N6A 5B9 (Canada) and Imaging Research Laboratories, Robarts Research Institute, London, Ontario N6A 5K8 (Canada); Department of Medical Biophysics, University of Western Ontario, London, Ontario N6A 5C1 (Canada) and Imaging Research Laboratories, Robarts Research Institute, London, Ontario N6A 5K8 (Canada); Imaging Research Laboratories, Robarts Research Institute, London, Ontario N6A 5K8 (Canada) and Division of Orthopaedic Surgery, University of Western Ontario and London Health Sciences Centre, London, Ontario N6A 4L6 (Canada); Division of Orthopaedic Surgery, University of Western Ontario and London Health Sciences Centre, London, Ontario N6A 4L6 (Canada); Biomedical Engineering Graduate Program, University of Western Ontario, London, Ontario N6A 5B9 (Canada); Department of Medical Biophysics, University of Western Ontario, London, Ontario N6A 5C1 (Canada) and Imaging Research Laboratories, Robarts Research Institute, London, Ontario N6A 5K8 (Canada)

    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

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

    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.

  7. The design and imaging characteristics of dynamic, solid-state, flat-panel x-ray image detectors for digital fluoroscopy and fluorography

    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

  8. A semiempirical linear model of indirect, flat-panel x-ray detectors

    Huang, Shih-Ying; Yang Kai; Abbey, Craig K.; Boone, John M. [Department of Biomedical Engineering, University of California, Davis, California, One Shields Avenue, Davis, California 95616 (United States) and Department of Radiology, University of California, Davis, Medical Center, 4860 Y Street, Ambulatory Care Center Suite 0505, Sacramento, California 95817 (United States); Department of Radiology, University of California, Davis, Medical Center, 4860 Y Street, Ambulatory Care Center Suite 0505, Sacramento, California 95817 (United States); Department of Psychological and Brain Sciences, University of California, Santa Barbara, California 92106 (United States); Department of Biomedical Engineering, University of California, Davis, California, One Shields Avenue, Davis, California 95616 (United States) and Department of Radiology, University of California, Davis, Medical Center, 4860 Y Street, Ambulatory Care Center Suite 3100, Sacramento, California 95817 (United States)

    2012-04-15

    Purpose: It is important to understand signal and noise transfer in the indirect, flat-panel x-ray detector when developing and optimizing imaging systems. For optimization where simulating images is necessary, this study introduces a semiempirical model to simulate projection images with user-defined x-ray fluence interaction. Methods: The signal and noise transfer in the indirect, flat-panel x-ray detectors is characterized by statistics consistent with energy-integration of x-ray photons. For an incident x-ray spectrum, x-ray photons are attenuated and absorbed in the x-ray scintillator to produce light photons, which are coupled to photodiodes for signal readout. The signal mean and variance are linearly related to the energy-integrated x-ray spectrum by empirically determined factors. With the known first- and second-order statistics, images can be simulated by incorporating multipixel signal statistics and the modulation transfer function of the imaging system. To estimate the semiempirical input to this model, 500 projection images (using an indirect, flat-panel x-ray detector in the breast CT system) were acquired with 50-100 kilovolt (kV) x-ray spectra filtered with 0.1-mm tin (Sn), 0.2-mm copper (Cu), 1.5-mm aluminum (Al), or 0.05-mm silver (Ag). The signal mean and variance of each detector element and the noise power spectra (NPS) were calculated and incorporated into this model for accuracy. Additionally, the modulation transfer function of the detector system was physically measured and incorporated in the image simulation steps. For validation purposes, simulated and measured projection images of air scans were compared using 40 kV/0.1-mm Sn, 65 kV/0.2-mm Cu, 85 kV/1.5-mm Al, and 95 kV/0.05-mm Ag. Results: The linear relationship between the measured signal statistics and the energy-integrated x-ray spectrum was confirmed and incorporated into the model. The signal mean and variance factors were linearly related to kV for each filter material (r

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

    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

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

    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. (paper)

  11. A camac based data acquisition system for flat-panel image array readout

    A readout system has been developed to facilitate the digitization and subsequent display of image data from two-dimensional, pixellated, flat-panel, amorphous silicon imaging arrays. These arrays have been designed specifically for medical x-ray imaging applications. The readout system is based on hardware and software developed for various experiments at CERN and Fermi National Accelerator Laboratory. Additional analog signal processing and digital control electronics were constructed specifically for this application. The authors report on the form of the resulting data acquisition system, discuss aspects of its performance, and consider the compromises which were involved in its design

  12. Daily quality control of collimator multi-leaf for IMRT static through flat panel (EPID)

    When techniques are employed such as radiotherapy for intensity modulated (IMRT) is necessary to establish a proper quality assurance program. According to national and international recommendations, such a program must include, in addition to verification of treatment for each patient, a multi-leaf collimator quality control daily, easy to perform and analyze, to ensure the quality of the given treatments daily. This paper intends to make such quality control through the irradiation of a number of fields in the imaging system flat panel portal and its subsequent analysis. (Author)

  13. A flat-panel x-ray detector for digital radiography and fluoroscopy

    A Flat-Panel X-ray detector is widely used for digital radiography and fluoroscopy. The outline of the detectors such as the structure, working principle, performance and clinical applications that are newly developed using this digital X-ray detector are described. An X-ray detector applying CdZnTe film which is expected to high detective efficiency is also reported. The characteristics of poly crystalline CdZnTe films, namely grain boundary affect the detector performance. To improve performance of the CdZnTe detector, control of the poly crystalline structure is required. (author)

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

    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

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

    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.

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

    Kyung Cha, Bo [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan (Korea, Republic of); Seo, Chang-Woo [Department of Radiation Convergence Engineering, College of Health Science, Yonsei University, Wonju (Korea, Republic of); Yang, Keedong [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan (Korea, Republic of); Jeon, Seongchae, E-mail: sarim@keri.re.kr [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan (Korea, Republic of); Huh, Young [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan (Korea, Republic of)

    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.

  17. Dose rate and beam profile measurement of proton beam using a flat panel detector

    Park, Jeong-Min

    2015-10-01

    A 20-MeV or 100-MeV proton beam is provided to users for their proton beam irradiation experiments at KOrea Multi-Purpose Accelerator Complex. Radiochromic film (Gafchromic / HDV2) has been used to measure the dose rate and the profile of an incident proton beam during irradiation experiments. However, such measurements using radiochromic film have some inconveniences because an additional scanning process of is required to quantify the film's image. Therefore, we tried to measure the dose rate and beam profile by using a flat panel detector (FPD), which was developed for X-ray radiography as a substitute for radiochromic film because the FPD can measure the beam profile and the dose rate directly through a digitized image with a high spatial resolution. In this work, we investigated the feasibility of using a FPD as a substitute for radiochromic film. The preliminary results for the beam profile and the dose rate measured by using the flat panel detector are reported in the paper.

  18. Evaluation of parallactic unsharpness caused by flat panel detector in digital radiography

    Objective: To evaluate the parallactic unsharpness caused by flat panel detector in digital radiography using different incident angle of central ray. Methods: R-l square-wave phantom was exposed by Kodak DR3000 system with X-ray tube angled 0°, 10°, 20°, 30°, and 40 respectively. Then, presampled modulation transfer function (MTF) was calculated for each case above. Subsequently, experimental data were processed and Wilcoxon signed ranks test were performed by statistic software SPSS 10.0, in which P<0.05 was considered as statistically significant difference. Results: The presampled MTF curves of incident angle of 0°-40° degree, were presented orderly from top to bottom, especially the incident angle of 40° was obviously the lowest. The incident angle of 0° was considered as a control group and other groups were compared against it. There was no statistically significant difference for MTF of incident angle of 10° (Z=-1.893, P=0.058), while there were significant difference for MTF of incident angle of 20°, 30°, and 40° (Z=-2.547, -2.666, -2.666, P<0.05). Conclusions: For flat panel detector in digital radiography, the bigger the incident angle of central ray, the larger the parallactic unsharpness. In addition, this effect has less influence on structures of low spatial frequency than those of high spatial frequency. (authors)

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

    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

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

    Chen, Daokun; Song, Xiaomeng; Zhang, Zhipeng; Chen, Jun, E-mail: stscjun@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, Sun Yat-sen University, Guangzhou 510275 (China); School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Li, Ziping [The First Affiliated Hospital, Sun Yat-sen University, Guangzhou 510275 (China); She, Juncong; Deng, Shaozhi; Xu, Ningsheng [State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, Sun Yat-sen University, Guangzhou 510275 (China); School of Microelectronics, Sun Yat-sen University, Guangzhou 510275 (China)

    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.

  1. Performance evaluation of flat panel detector in x-ray fluoroscopy

    Full text: Flat panel detectors are currently replacing the conventional image intensifiers in R-F imaging. We evaluated the performance of a biplane cardiac imaging system (Siemens Axiom Artis dBC), the image acquisition was based on a 25 cm diagonal digital fiat panel detector. Performance characteristics included image quality, typical patient entrance dose and measurement of input to the surface of flat detector. The results were compared with conventional image intensifier systems (Siemens Hicor Unit and Toshiba DPF 2000 A Biplane Unit) used in cardiac imaging at Westmead. Image quality and dose measurements were performed following standard protocols using Westmead test object and 20 cm solid water as absorber in the beam. For measurement of input to the surface of flat detector, 2 mm copper was placed on the collimator. Radcal 3cc and 180 cc ion chambers were used for dose measurements. Image quality: Our measurements on flat panel system indicate that high contrast resolution and threshold contrast is not affected by changing field size. This is expected due to minimum loss of signal in the imaging chain of digital systems and the independence of detector pixel size with change in field of view. While low contrast resolution was found to be similar to conventional systems, high contrast resolution was significantly superior using flat detector system for large and intermediate field of view (25-28 1p/cm against 18-20). Typical patient dose as measured using flat detector system was similar to the conventional Toshiba pulsed fluoroscopy system( ∼ 3 - 8 mGy/min depending on the field size). This was 40-50 % lower than our old Siemens hicore unit. Input to the surface of flat detector was found to vary with field size as is the case with a conventional II system. As described elsewhere, although there is no necessity to increase exposure or video gain in a digital magnification, digital data interpolation process introduces noise. As a result system

  2. Development and evaluation of a digital radiography system using a large-area flat-panel detector

    Suzuki, Katsumi; Ikeda, Shigeyuki; Ishikawa, Ken; Iinuma, Gen; Ogasawara, Satoshi; Moriyama, Noriyuki; Konno, Yasutaka

    2002-05-01

    A new DR system using a large-area flat panel detector (FPD) with a 40 by 30 cm active area and a 194 micrometers pixel pitch, has been developed to compare with a conventional image intensifier and charge-coupled device camera type DR system. After measuring basic characteristics of the new DR system such as signal-to-noise ratio, modulation transfer function, and detective quantum efficiency, we applied the FPD to a Gastro-Intestinal study with contrast media, and discussed its potential for clinical use with a medical doctor. In radiography mode, the new DR system with a large-are FPD has superior image quality compared with the conventional I.I.- CCD camera type DR system because of high SNR and DQE. In fluoroscopy mode, the SNR of the new DR system at the exposure range of over 2(mu) R/frame is similar with the conventional I.I.-CCD camera type DR system. As a result, we considered that new DR system with a large-area FPD could be applied to a clinical study replacing an I.I.-CCD camera type. In the evaluation using various clinical images taken with the new DR system by a medical doctor, the new DR system with a large-are FPD performed sufficiently for a GI study.

  3. Investigation of Vertical Drag and Periodic Airloads Acting on Flat Panels in a Rotor Slipstream

    Makofski, Robert A; Menkick, George F

    1956-01-01

    Tests have been conducted on the Langley helicopter test tower to determine the vertical drag and pressure distributions on flat panels mounted below a helicopter rotor. Calculations of the vertical drag by use of a strip-analysis procedure outlined in the paper and the assumption of a fully contracted wake agreed well with the experimental results over the range from 0.2 to 0.64 rotor radius beneath the plane of zero flapping. The pressure increase caused by the passage of the blade over the panel is a maximum at about the 0.8 radius spanwise station. At this station, the pressure decreases from 10 times the disk loading per blade at 0.05 radius beneath the rotor plane of zero flapping to one-half of the disk loading per blade at 0.64 radius beneath the plane of zero flapping.

  4. Amorphous silicon thin film transistor active-matrix organic light-emitting diode displays fabricated on flexible substrates

    Nichols, Jonathan A.

    Organic light-emitting diode (OLED) displays are of immense interest because they have several advantages over liquid crystal displays, the current dominant flat panel display technology. OLED displays are emissive and therefore are brighter, have a larger viewing angle, and do not require backlights and filters, allowing thinner, lighter, and more power efficient displays. The goal of this work was to advance the state-of-the-art in active-matrix OLED display technology. First, hydrogenated amorphous silicon (a-Si:H) thin film transistor (TFT) active-matrix OLED pixels and arrays were designed and fabricated on glass substrates. The devices operated at low voltages and demonstrated that lower performance TFTs could be utilized in active-matrix OLED displays, possibly allowing lower cost processing and the use of polymeric substrates. Attempts at designing more control into the display at the pixel level were also made. Bistable (one bit gray scale) active-matrix OLED pixels and arrays were designed and fabricated. Such pixels could be used in novel applications and eventually help reduce the bandwidth requirements in high-resolution and large-area displays. Finally, a-Si:H TFT active-matrix OLED pixels and arrays were fabricated on a polymeric substrate. Displays fabricated on a polymeric substrates would be lightweight; flexible, more rugged, and potentially less expensive to fabricate. Many of the difficulties associated with fabricating active-matrix backplanes on flexible substrates were studied and addressed.

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

    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.

  6. Establishment of action levels for quality control of IMRT flat panel: experience with the algorithm iGRiMLO

    Algorithm has been used at our institution iGRiMLO scheduled for individual verification of treatment plans for intensity modulated radiotherapy (IMRT) step and shoot through portal dosimetry pretreatment of non-transmission, triggering the plan directly to a portal imaging device (EPID) of an amorphous silicon flat panel.

  7. Distal Radius in Adolescent Girls with Anorexia Nervosa: Trabecular Structure Analysis with High-Resolution Flat-Panel Volume CT

    Bredella, Miriam A.; Misra, Madhusmita; Miller, Karen K.; Madisch, Ijad; Sarwar, Ammar; Cheung, Arnold; Klibanski, Anne; Gupta, Rajiv

    2008-01-01

    Purpose: To examine trabecular microarchitecture with high-resolution flat-panel volume computed tomography (CT) and bone mineral density (BMD) with dual-energy x-ray absorptiometry (DXA) in adolescent girls with anorexia nervosa (AN) and to compare these results with those in normal-weight control subjects.

  8. Comparing Ovarian Radiation Doses in Flat-Panel and Conventional Angiography During Uterine Artery Embolization: A Randomized Clinical Trial

    Uterine artery embolization (UAE) is a minimally invasive procedure performed under fluoroscopy for the treatment of uterine fibroids and accompanied by radiation exposure. To compare ovarian radiation doses during uterine artery embolization (UAE) in patients using conventional digital subtraction angiography (DSA) with those using digital flat-panel technology. Thirty women who were candidates for UAE were randomly enrolled for one of the two angiographic systems. Ovarian doses were calculated according to in-vitro phantom study results using entrance and exit doses and were compared between the two groups. The mean right entrance dose was 1586±1221 mGy in the conventional and 522.3±400.1 mGy in the flat panel group (P=0.005). These figures were 1470±1170 mGy and 456±396 mGy, respectively for the left side (P=0.006). The mean right exit dose was 18.8±12.3 for the conventional and 9.4±6.4 mGy for the flat panel group (P=0.013). These figures were 16.7±11.3 and 10.2±7.2 mGy, respectively for the left side (P=0.06). The mean right ovarian dose was 139.9±92 in the conventional and 23.6±16.2 mGy in the flat panel group (P<0.0001). These figures were 101.7±77.6 and 24.6±16.9 mGy, respectively for the left side (P=0.002). Flat panel system can significantly reduce the ovarian radiation dose during UAE compared with conventional DSA

  9. Assessment of image quality and radiation dose on a modern flat panel angiography system

    Full text: Angiographic procedures are often associated with high patient and staff dose that can be reduced without image quality deterioration. This work is on assessment of image quality and patient doses on a modern flat panel angiography unit. Because of the limited number of digital systems in Bulgaria, quality control protocol for testing these units does not exist currently and this work is aimed to develop and test the methodology. Methods and materials. A GE Innova 4100 Flat Panel Detector angiography unit was examined. Low and high contrast resolutions were assessed using FL18 test object placed at the isocentre between the sheets of a PMMA phantom with total thickness varying from 16 to 30 cm for FOV of 16 to 40 cm at pulsed fluoro mode of 30 frames/s. The image detector was set up at 5 cm above the 30 cm PMAA phantom. The Entrance Surface Dose Rate was measured by Mult-O-Meter dosimeter (Unfors, Sweden). The Incident Dose rate and Dose Area Product were measured with Diamentor M4-KDK (PTW, Germany) for the same FOVs and phantom thicknesses. The quality of images at acquisition mode was examined also using DIGI 13 test object (Wellhofer, Germany). The homogeneity, dynamic range, alignment, high contrast spatial resolution and low contrast resolution and signal-to-noise ratio were measured. The digital subtraction angiography image quality was examined using RoVi-8 test tool (Wellhofer, Germany). Results and discussion. The Entrance Surface Dose Rate measured for 20 cm PMAA and the 40 cm FOV, 30 frames/s was 11,29 mGy.min-1 and 5,58 mGy.min-1 for the 'normal' and 'low' mode, respectively. The dosimetric results obtained via both dosimeters are used for calculation of calibration coefficients for the DAP and ESD values shown by the system on the display monitor at the control console. The low contrast sensitivity varies from 1,6% to 6,6% depending on the thickness of PMAA phantom and FOV, as the limiting spatial resolution is changing from 2,24 to 1,12 lp

  10. Design and performance characteristics of a digital flat-panel computed tomography system

    Computed tomography (CT) applications continue to expand, and they require faster data acquisition speeds and improved spatial resolution. Achieving isotropic resolution, by means of cubic voxels, in combination with longitudinal coverage beyond 20 mm would represent a substantial advance in clinical CT because few commercially available scanners are capable of this at present. To achieve this goal, a prototype CT system incorporating a movable array of 20 cmx20 cm, 200-μm-pitch amorphous silicon flat-panel x-ray detectors and a conventional CT x-ray source was constructed at the General Electric Global Research Center and performance tested at The University of Texas M. D. Anderson Cancer Center. The device was designed for preclinical imaging applications and has a scan field of 13 to 33 cm, with a magnification of 1.5. Image quality performance measurements, such as spatial and contrast resolutions, were obtained using both industry standard and custom phantoms. Spatial resolution, quantified by the system's modulation transfer function, indicated improvement by a factor of 2.5 to 5 in isotropic spatial resolution over current commercially available systems, with 10% modulation transfer function modulations at frequencies from 19 to 31 lp/cm. Low-contrast detectability results were obtained from industry-standard phantoms and were comprised of embedded contrast regions of 0.3%, 0.5%, and 1.0% over areas of several mm2. Performance was sufficient to easily distinguish 1.0% contrast regions down to 2 mm in diameter relative to the background. On the basis of scans of specialized hydroxyapatite phantoms, the system response is extremely linear (R2=0.990) in bone-equivalent density regimens. Standard CT dose index CTDI100 and CTDIW measurements were also conducted to assess dose delivery using a 16-cm-CTDI phantom and a 120 kV 120 mAs scan technique. The CTDIW ranged from 30 mGy (one-panel mode) to 113 mGy (two-panel mode) for this system. Lastly, several in vivo

  11. Investigation of the dosimetric properties of an a-Si flat panel epid

    Full text: Electronic portal imaging devices (EPIDs) are primarily used as an electronic replacement for film to verify the set-up of radiotherapy patients based on imaged anatomy. There has recently been much interest in the use of amorphous silicon (a-Si) flat panel EPIDs for dosimetric verification in radiotherapy. The work presented here has been carried out to determine their suitability for dosimetric applications by investigating some of the basic response characteristics and the implications these might have. The measurements reported in this paper were performed using 6-MV photon beams from an Elekta Precise linear accelerator fitted with Elekta iViewGT amorphous silicon flat panel EPIDs. Measurements were performed to investigate the response of the EPID as a function of exposure and field size. Similar measurements were made with an ionisation chamber for comparison. Further measurements were carried out to investigate the response of the EPID to multiple low dose exposures (e.g. 5x2 MU) such as might be encountered in Intensity Modulated Radiotherapy (IMRT). This was compared with the response to a single high dose exposure (e.g. 10 MU) and repeated for a range of exposures. The results show the response of the EPID, to a good approximation, to be linear with dose over the range of 1 -200 MU. However, 'under-responses' in the EPID of up to 5% were seen at the lowest exposures. For multiple low dose segments the sum of the EPID responses was found to be less than the response to the same total exposure in a single large segment. This effect reduces with increase in the magnitude of the low dose segments. The variation in EPID response with field size was found to be greater than that indicated by the ionisation chamber. The results show that the a-Si detector responds to dose, to a good approximation, in a linear manner. The EPID under-response at low doses is thought to be related to the so called ghosting effect. Each image frame has a residual

  12. Flat panel CT following stapes prosthesis insertion: an experimental and clinical study

    Anatomical information of the middle and inner ear is becoming increasingly important in post-operative evaluation especially after stapesplasty with unsuccessful improvement of the air-bone gap (ABG). So far computed tomography (CT) has been the first choice for detection of reasons for recurrent hearing loss. CT has the disadvantage of metal-induced artefacts after insertion of middle ear implants and of a relatively high irradiation dose. Flat panel CT (fpCT) was performed in three temporal bone specimen after experimental insertion of different stapes prostheses, aiming to validate the accuracy of fpCT of the middle and inner ear. Additionally, 28 consecutive patients, supplied with different stapes prostheses underwent post-operative fpCT to compare the pre- and post-operative hearing results with the determined prosthesis position in the middle and inner ear. In all cases, fpCT showed a statistically significant correlation between hearing improvement and prosthesis position. This technique provided detailed post-operative information of the implant position in patients and temporal bone specimen. The new imaging technique of fpCT allows the immediate and almost artefact-free evaluation of surgical results following stapesplasty. Further benefits are a lower irradiation dose and higher isovolumetric resolution compared with standard CT. (orig.)

  13. Point spread function modeling method for x-ray flat panel detector imaging

    Zhang, Hua; Shi, Yikai; Huang, Kuidong; Yu, Qingchao

    2012-10-01

    Flat panel detector (FPD) has been widely used as the imaging unit in the current X-ray digital radiography (DR) systems and Computed Tomography (CT) systems. Point spread function (PSF) is an important indicator of the FPD imaging system, but also the basis for image restoration. For the problem of poor accuracy of the FPD's PSF measurement with the original pinhole imaging for DR systems, a new PSF measuring method with the pinhole imaging based on the image restoration is proposed in this paper. Firstly, some images collected with the pinhole imaging are averaged to one image to reducing the noise. Then, the original pinhole image is calculated according to the energy conservation principle of point spread. Finally, the PSF of the FPD is obtained using the operation of image restoration. On this basis, through the fitting of the characteristic parameters of the PSF on different scan conditions, the computational model of the PSF is established for any scan conditions. Experimental results show that the method can obtain a more accurate PSF of the FPD, and the PSF of the same system under any scan conditions can be directly calculated with the PSF model.

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

    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.

  15. Clinical investigation of flat panel CT following middle ear reconstruction: a study of 107 patients

    After middle ear reconstruction using partial or total ossicular replacement prostheses (PORP/TORP), an air-bone gap (ABG) may persist because of prosthesis displacement or malposition. So far, CT of the temporal bone has played the main role in the diagnosis of reasons for postoperative insufficient ABG improvement. Recent experimental and clinical studies have evaluated flat panel CT (fpCT) as an alternative imaging technique that provides images with high isovolumetric resolution, fewer metal-induced artefacts and lower irradiation doses. One hundred and seven consecutive patients with chronic otitis media with or without cholesteatoma underwent reconstruction by PORP (n = 52) or TORP (n = 55). All subjects underwent preoperative and postoperative audiometric testing and postoperative fpCT. Statistical evaluation of all 107 patients as well as the sole sub-assembly groups (PORP or TORP) showed a highly significant correlation between hearing improvement and fpCT-determined prosthesis position. FpCT enables detailed postoperative information on patients with middle ear reconstruction. FpCT is a new imaging technique that provides immediate feedback on surgical results after reconstructive middle ear surgery. Specific parameters evaluated by fpCT may serve as a predictive tool for estimated postoperative hearing improvement. Therefore this imaging technique is suitable for postoperative quality control in reconstructive middle ear surgery. (orig.)

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

    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.

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

    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.

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

    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

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

    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.

  20. Transition from image intensifier to flat panel detector in interventional cardiology: Impact of radiation dose

    Roshan S Livingstone

    2015-01-01

    Full Text Available Flat panel detector (FPD technology in interventional cardiology is on the increase due to its varied advantages compared to the conventional image intensifier (II systems. It is not clear whether FPD imparts lower radiation doses compared to II systems though a few studies support this finding. This study intends to compare radiation doses from II and FPD systems for coronaryangiography (CAG and Percutaneous Transluminal Coronary Angioplasty (PTCA performed in a tertiary referral center. Radiation doses were measured using dose area product (DAP meter from patients who underwent CAG (n = 222 and PTCA (n = 75 performed using FPD angiography system. The DAP values from FPD were compared with earlier reported data using II systems from the same referral center where the study was conducted. The mean DAP values from FPD system for CAG and PTCA were 24.35 and 63.64 Gycm 2 and those from II system were 27.71 and 65.44 Gycm 2 . Transition from II to FPD system requires stringent dose optimization strategies right from the initial period of installation.

  1. Development of patient collation system by kinetic analysis for chest dynamic radiogram with flat panel detector

    Tsuchiya, Yuichiro; Kodera, Yoshie

    2006-03-01

    In the picture archiving and communication system (PACS) environment, it is important that all images be stored in the correct location. However, if information such as the patient's name or identification number has been entered incorrectly, it is difficult to notice the error. The present study was performed to develop a system of patient collation automatically for dynamic radiogram examination by a kinetic analysis, and to evaluate the performance of the system. Dynamic chest radiographs during respiration were obtained by using a modified flat panel detector system. Our computer algorithm developed in this study was consisted of two main procedures, kinetic map imaging processing, and collation processing. Kinetic map processing is a new algorithm to visualize a movement for dynamic radiography; direction classification of optical flows and intensity-density transformation technique was performed. Collation processing consisted of analysis with an artificial neural network (ANN) and discrimination for Mahalanobis' generalized distance, those procedures were performed to evaluate a similarity of combination for the same person. Finally, we investigated the performance of our system using eight healthy volunteers' radiographs. The performance was shown as a sensitivity and specificity. The sensitivity and specificity for our system were shown 100% and 100%, respectively. This result indicated that our system has excellent performance for recognition of a patient. Our system will be useful in PACS management for dynamic chest radiography.

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

    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). (orig.)

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

    Gupta, Rajiv; Brady, Tom [Massachusetts General Hospital, Department of Radiology, Founders House, FND-2-216, Boston, MA (United States); Grasruck, Michael; Suess, Christoph; Schmidt, Bernhard; Stierstorfer, Karl; Popescu, Stefan; Flohr, Thomas [Siemens Medical Solutions, Forchheim (Germany); Bartling, Soenke H. [Hannover Medical School, Department of Neuroradiology, Hannover (Germany)

    2006-06-15

    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). (orig.)

  4. Average power scaling of UV excimer lasers drives flat panel display and lidar applications

    Herbst, Ludolf; Delmdahl, Ralph F.; Paetzel, Rainer

    2012-03-01

    Average power scaling of 308nm excimer lasers has followed an evolutionary path over the last two decades driven by diverse industrial UV laser microprocessing markets. Recently, a new dual-oscillator and beam management concept for high-average power upscaling of excimer lasers has been realized, for the first time enabling as much as 1.2kW of stabilized UV-laser average output power at a UV wavelength of 308nm. The new dual-oscillator concept enables low temperature polysilicon (LTPS) fabrication to be extended to generation six glass substrates. This is essential in terms of a more economic high-volume manufacturing of flat panel displays for the soaring smartphone and tablet PC markets. Similarly, the cost-effective production of flexible displays is driven by 308nm excimer laser power scaling. Flexible displays have enormous commercial potential and can largely use the same production equipment as is used for rigid display manufacturing. Moreover, higher average output power of 308nm excimer lasers aids reducing measurement time and improving the signal-to-noise ratio in the worldwide network of high altitude Raman lidar stations. The availability of kW-class 308nm excimer lasers has the potential to take LIDAR backscattering signal strength and achievable altitude to new levels.

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

    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. PMID:27294264

  6. Potential Applications of Flat-Panel Volumetric CT in Morphologic, Functional Small Animal Imaging

    Susanne Greschus

    2005-08-01

    Full Text Available Noninvasive radiologic imaging has recently gained considerable interest in basic, preclinical research for monitoring disease progression, 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, brain of mice. The high image quality of chest scans enables the visualization of small lung nodules in an orthotopic lung cancer model, the reliable imaging of therapy side effects such as lung fibrosis. Using contrast-enhanced scans, fpVCT displayed the vascular trees of the brain, liver, 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, 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.

  7. A performance comparison of direct- and indirect-detection flat-panel imagers

    Partridge, M; Müller, L

    2002-01-01

    A comparison of the performance of a direct- and an indirect-detection amorphous silicon flat-panel X-ray imager is presented for a 6 MV beam. Experimental measurements of the noise characteristics, image lag, spectral response, spatial resolution and quantum efficiency are described, compared and discussed. The two systems are comprised of 512x512 pixel, 400 mu m pitch, arrays of a-Si:H p-i-n photodiodes and thin-film transistors. In the direct-detection system, X-rays interact to produce electron/hole pairs directly in the silicon photodiodes. For the indirect-detection system, a phosphor screen converts energy from the incident X-rays into visible light, which is then detected by the photodiodes. Both systems are shown to be quantum noise limited, with the total electronic noise in the detector 10-15 times smaller than the Poisson noise level in detected signal. The measured lag for both systems is 1.0+-0.1% or less in the first frame with subsequent signals decaying exponentially with frame read-out, with...

  8. Flat panel CT following stapes prosthesis insertion: an experimental and clinical study

    Zaoui, K. [University-Hospital Heidelberg, Ludwig-Karls-University Heidelberg, Department of Otorhinolaryngology, Head and Neck Surgery, Heidelberg (Germany); Kromeier, J. [St.-Josefs-Hospital, RkK, Department of Radiology, Freiburg (Germany); Neudert, M.; Zahnert, T. [University-Hospital Dresden, Technical-University Dresden, Department of Otorhinolaryngology, Head and Neck Surgery, Dresden (Germany); Boedeker, C.C.; Laszig, R.; Offergeld, C. [University-Hospital Freiburg, Albert-Ludwigs-University Freiburg, Department of Otorhinolaryngology, Head and Neck Surgery, Freiburg (Germany)

    2012-04-15

    Anatomical information of the middle and inner ear is becoming increasingly important in post-operative evaluation especially after stapesplasty with unsuccessful improvement of the air-bone gap (ABG). So far computed tomography (CT) has been the first choice for detection of reasons for recurrent hearing loss. CT has the disadvantage of metal-induced artefacts after insertion of middle ear implants and of a relatively high irradiation dose. Flat panel CT (fpCT) was performed in three temporal bone specimen after experimental insertion of different stapes prostheses, aiming to validate the accuracy of fpCT of the middle and inner ear. Additionally, 28 consecutive patients, supplied with different stapes prostheses underwent post-operative fpCT to compare the pre- and post-operative hearing results with the determined prosthesis position in the middle and inner ear. In all cases, fpCT showed a statistically significant correlation between hearing improvement and prosthesis position. This technique provided detailed post-operative information of the implant position in patients and temporal bone specimen. The new imaging technique of fpCT allows the immediate and almost artefact-free evaluation of surgical results following stapesplasty. Further benefits are a lower irradiation dose and higher isovolumetric resolution compared with standard CT. (orig.)

  9. Clinical investigation of flat panel CT following middle ear reconstruction: a study of 107 patients

    Zaoui, K. [University Hospital Heidelberg, Ruprecht Karls University, Department of Otorhinolaryngology, Head and Neck Surgery, Heidelberg (Germany); Kromeier, J. [St. Josefs Hospital, RkK, Department of Radiology, Freiburg (Germany); Neudert, M.; Beleites, T.; Zahnert, T. [University Hospital Dresden, Technical University, Department of Otorhinolaryngology, Head and Neck Surgery, Dresden (Germany); Laszig, R.; Offergeld, C. [University Hospital Freiburg, Albert Ludwigs University, Department of Otorhinolaryngology, Head and Neck Surgery, Freiburg (Germany)

    2014-03-15

    After middle ear reconstruction using partial or total ossicular replacement prostheses (PORP/TORP), an air-bone gap (ABG) may persist because of prosthesis displacement or malposition. So far, CT of the temporal bone has played the main role in the diagnosis of reasons for postoperative insufficient ABG improvement. Recent experimental and clinical studies have evaluated flat panel CT (fpCT) as an alternative imaging technique that provides images with high isovolumetric resolution, fewer metal-induced artefacts and lower irradiation doses. One hundred and seven consecutive patients with chronic otitis media with or without cholesteatoma underwent reconstruction by PORP (n = 52) or TORP (n = 55). All subjects underwent preoperative and postoperative audiometric testing and postoperative fpCT. Statistical evaluation of all 107 patients as well as the sole sub-assembly groups (PORP or TORP) showed a highly significant correlation between hearing improvement and fpCT-determined prosthesis position. FpCT enables detailed postoperative information on patients with middle ear reconstruction. FpCT is a new imaging technique that provides immediate feedback on surgical results after reconstructive middle ear surgery. Specific parameters evaluated by fpCT may serve as a predictive tool for estimated postoperative hearing improvement. Therefore this imaging technique is suitable for postoperative quality control in reconstructive middle ear surgery. (orig.)

  10. Clinical evaluation of digital angiographic system equipped with the Safire' flat-panel detector of a direct conversion type

    This report presents a report on clinical evaluation of our newly developed flat-panel X-ray detector of a direct conversion type, designed to provide images of a resolution higher than, or at least equal to, that ensured by X-ray photographic films, in clinical digital X-ray cinematography. This new detector was named 'Safire' the acronym of 'Shimadzu advanced flat imaging receptor', emphasizing its high technological level, such as the capability to ensure high quality of images. The clinical evaluation of Shimadzu DIGITEX Premier digital angiography system, equipped with this new flat-panel X-ray detector of a direct conversion type, has been started in March, 2003, at the Kokura Memorial Hospital in Kyushu, Japan. (author)

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

    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

  12. Semi-Automatic Classification of Skeletal Morphology in Genetically Altered Mice Using Flat-Panel Volume Computed Tomography

    Christian Dullin; Jeannine Missbach-Guentner; Vogel, Wolfgang F.; Eckhardt Grabbe; Frauke Alves

    2007-01-01

    Rapid progress in exploring the human and mouse genome has resulted in the generation of a multitude of mouse models to study gene functions in their biological context. However, effective screening methods that allow rapid noninvasive phenotyping of transgenic and knockout mice are still lacking. To identify murine models with bone alterations in vivo, we used flat-panel volume computed tomography (fpVCT) for high-resolution 3-D imaging and developed an algorithm with a computational intelli...

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

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

  14. Women with Anorexia Nervosa: Finite Element and Trabecular Structure Analysis by Using Flat-Panel Volume CT

    Walsh, Conor J.; Phan, Catherine M.; Misra, Madhusmita; Bredella, Miriam A.; Miller, Karen K.; Fazeli, Pouneh K.; Bayraktar, Harun H.; Klibanski, Anne; Gupta, Rajiv

    2010-01-01

    We have shown reduced failure load and stiffness of the distal radius in women with anorexia nervosa (AN) compared with age-matched control subjects by using finite element models created from 150-μm resolution flat-panel volume CT; reductions in trabecular bone volume fraction, trabecular number, and bone mineral density and an increase in trabecular separation were observed in the AN group.

  15. Effect on image data resampling in evaluation of the basic imaging properties for a digital radiographic system based on a flat panel detector

    We investigated the effect on image data resampling in an evaluation of the basic imaging properties for a digital radiographic system based on a flat panel detector (FPD). One of the latest digital radiographic systems was used in this study. This system was based on a direct-conversion FPD of amorphous selenium. The basic imaging properties of the system were evaluated by measuring characteristic curve, presampled modulation transfer function (MTF), and Wiener spectrum (WS) using Digital Imaging and Communications in Medicine (DICOM) image with a matrix size of 2048 x 2048. The evaluations were performed under two conditions because matrix size automatically changes according to the selection of imaging size. One of the conditions was a different matrix size between image data acquired on the FPD and the output image (DICOM image for which resampling was performed). The other condition was that these matrices be the same size (DICOM image with no resampling performed). Resampling did not affect the characteristic curves. However, MTF and the WS obtained from the resampled data were different from those of the one not resampled, which is considered to be the 'inherent' basic imaging properties, and this phenomenon was remarkable, especially in terms of the MTFs. Our study indicates that the effect on resampling should not be disregarded in evaluating the basic imaging properties of digital radiographic systems. Therefore, it is mandatory to use DICOM images for which no resampling was performed in order to evaluate the inherent basic imaging properties for digital radio graphic systems. (author)

  16. CAS 132-2006 Standard for Flat Panel Display TV Set Installation Service Formulating and Enforcing Main Point Explanation and Analysis

    2007-01-01

    @@ CAS 132-2006 formulation background and work courses Flat panel display technology is maturing alongside the development of science and technology. The prices of flat panel display TV sets are becoming lower and lower. Flat panel display TV sets have begun entering the mainstream and are now the first choice of some consumers when making new TV purchases.Display TV Set Installation Service Point Explanation and AnalysisRepair, Retreat and Change Duty Stipulations. Peculiar use conditions, usage environments, and the practical circumstances of user consumption service requirements, etc., were also taken into account on the basis of extensive investigation, testing, and verification.

  17. Cone Beam Breast CT with a Flat Panel Detector- Simulation, Implementation and Demonstration.

    Shaw, Chris; Chen, Lingyun; Altunbas, Mastafa; Tu, Shuju; Wang, Tian-Peng; Lai, Chao-Jen; Cheenu Kappadath, S; Meng, Yang; Liu, Xinming

    2005-01-01

    This paper describes our experiences in the simulation, implementation and application of a flat panel detector based cone beam computed tomography (CT) imaging system for dedicated 3-D breast imaging. In our simulation study, the breast was analytically modeled as a cylinder of breast tissue loosely molded into cylindrical shape with embedded soft tissue masses and calcifications. Attenuation coefficients for various types of breast tissue, soft tissue masses and calcifications were estimated for various kVp's to generate simulated image signals. Projection images were computed to incorporate x-ray attenuation, geometric magnification, x-ray detection, detector blurring, image pixelization and digitization. Based on the x-ray kVp/filtration used, transmittance through the phantom, detective quantum efficiency (DQE), exposure level, and imaging geometry, the photon fluence was estimated and used to compute the quantum noise level on a pixel-by-pixel basis for various dose levels at the isocenter. This estimated noise level was then used with a random number generator to generate 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 simulate detector blurring. Additional 2-D Gaussian filtering was applied to the projection images and tested for improving the detection of soft tissue masses and calcifications in the reconstructed images. Reconstruction was performed using the Feldkamp filtered backprojection algorithm. All simulations were performed on a 24 PC (2.4 GHz Dual-Xeon CPU) cluster with MPI parallel programming. PMID:17281227

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

    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. PMID:23494400

  19. Optimization of outdoor cultivation in flat panel airlift reactors for lipid production by Chlorella vulgaris.

    Münkel, Ronja; Schmid-Staiger, Ulrike; Werner, Achim; Hirth, Thomas

    2013-11-01

    Microalgae are discussed as a potential renewable feedstock for biofuel production. The production of highly concentrated algae biomass with a high fatty acid content, accompanied by high productivity with the use of natural sunlight is therefore of great interest. In the current study an outdoor pilot plant with five 30 L Flat Panel Airlift reactors (FPA) installed southwards were operated in 2011 in Stuttgart, Germany. The patented FPA reactor works on the basis of an airlift loop reactor and offers efficient intermixing for homogeneous light distribution. A lipid production process with the microalgae Chlorella vulgaris (SAG 211-12), under nitrogen and phosphorous deprivation, was established and evaluated in regard to the fatty acid content, fatty acid productivity and light yield. In the first set of experiments limitations caused by restricted CO₂ availability were excluded by enriching the media with NaOH. The higher alkalinity allows a higher CO₂ content of supplied air and leads to doubling of fatty acid productivity. The second set of experiments focused on how the ratio of light intensity to biomass concentration in the reactor impacts fatty acid content, productivity and light yield. The specific light availability was specified as mol photons on the reactor surface per gram biomass in the reactor. This is the first publication based on experimental data showing the quantitative correlation between specific light availability, fatty acid content and biomass light yield for a lipid production process under nutrient deprivation and outdoor conditions. High specific light availability leads to high fatty acid contents. Lower specific light availability increases fatty acid productivity and biomass light yield. An average fatty acid productivity of 0.39 g L⁻¹  day⁻¹ for a 12 days batch process with a final fatty acid content of 44.6% [w/w] was achieved. Light yield of 0.4 g mol photons⁻¹ was obtained for the first 6 days of

  20. Evaluation of image quality and appropriate X-ray exposure of a flat panel detector

    We evaluated image quality and necessary patient exposure when using the CXDI-11 (Canon Inc.) flat panel detector (FPD). This detector, which consists of a rare earth fluorescent screen (Gd2O2S: Tb) and amorphous silicon sensor, was compared with the FCR-5000 (Fuji Film Medical Co., Ltd.) CR and the UR-3/HGM2 (Fuji Film Medical Co., Ltd.) film-screen (F/S) combination. Comparisons of both physical imaging characteristics and clinical image quality were carried out. The final MTF of the FPD was found to be similar to or better than those of the CR and F/S systems. For identical exposures, the overall Wiener spectrum of the FPD was found to be slightly poorer than that of the F/S combination. The NEQ of the FPD was found to be similar to or better than those of the CR and F/S systems. Comparison of chest images showed that the FPD produced images with quality comparable to or higher than those of the CR system. Similarly, evaluation of abdominal and bone images using a 5-scale method showed that the FPD produced images with quality comparable to or higher than those of the CR system. As with CR, the x-ray quantum mottle in FPD images becomes noticeable at low exposures. Clinical images were therefore taken with a 30% increase in exposure, giving a Wiener spectrum for the FPD images similar to that obtained with the F/S images. This is probably not a significant increase in exposure, given the improvement in image quality and increased ease of use provided by the CXDI system. Further, future improvements in hardware and image processing may allow images to be taken with the same exposure used for F/S images. Our evaluation of both image quality and x-ray exposure has therefore indicated the value of the FPD in the clinical environment. (author)

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

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

    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

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

    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

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

    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.

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

    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

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

    Wang, Qiang, E-mail: wangqiang@mir.wustl.edu [Washington University in St Louis, MO 63110 (United States); Wen, Jie; Ravindranath, Bosky; O' Sullivan, Andrew W. [Washington University in St Louis, MO 63110 (United States); Catherall, David [Saint Louis University, St. Louis, MO 63103 (United States); Li, Ke; Wei, Shouyi; Komarov, Sergey [Washington University in St Louis, MO 63110 (United States); Tai, Yuan-Chuan, E-mail: taiy@mir.wustl.edu [Washington University in St Louis, MO 63110 (United States)

    2015-09-11

    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 mm{sup 3} with 1.0 mm pitch. The outer diameter of the detector block is 16.8×16.8 mm{sup 2}. 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 {sup 68}Ge 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.

  7. Digital radiology using active matrix readout of amorphous selenium: radiation hardness of cadmium selenide thin film transistors.

    Zhao, W; Waechter, D; Rowlands, J A

    1998-04-01

    A flat-panel x-ray imaging detector using active matrix readout of amorphous selenium (a-Se) is being investigated for digital radiography and fluoroscopy. The active matrix consists of a two-dimensional array of thin film transistors (TFTs). Radiation penetrating through the a-Se layer will interact with the TFTs and it is important to ensure that radiation induced changes will not affect the operation of the x-ray imaging detector. The methodology of the present work is to investigate the effects of radiation on the characteristic curves of the TFTs using individual TFT samples made with cadmium selenide (CdSe) semiconductor. Four characteristic parameters, i.e., threshold voltage, subthreshold swing, field effect mobility, and leakage current, were examined. This choice of parameters was based on the well established radiation damage mechanisms for crystalline silicon metal-oxide-semiconductor field-effect transistors (MOSFETs), which have a similar principle of operation as CdSe TFTs. It was found that radiation had no measurable effect on the leakage current and the field effect mobility. However, radiation shifted the threshold voltage and increased the subthreshold swing. But even the estimated lifetime dose (50 Gy) of a diagnostic radiation detector will not affect the normal operation of an active matrix x-ray detector made with CdSe TFTs. The mechanisms of the effects of radiation will be discussed and compared with those for MOSFETs and hydrogenated amorphous silicon (a-Si:H) TFTs. PMID:9571621

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

    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

  9. A 25 kW solar photovoltaic flat panel power supply for an electrodialysis water desalination unit in New Mexico

    Wood, J. R.; Crutcher, J. L.

    1980-06-01

    The stand-alone system consists of a flat panel array employing silicon ribbon solar cells, used in conjunction with a lead-acid battery bank. Electrodialysis is an energy-conservative process for the desalination of water, in which ions are transferred from one solution through a membrane into another solution by imposition of a direct electrical current. The system design is intended to be prototypical of part of the drinking water supply for a remote village. The specific task of this system is to aid in the restoration of an aquifer following a uranium leaching operation.

  10. Circle plus Partial Helical Scan Scheme for a Flat Panel Detector-Based Cone Beam Breast X-Ray CT

    Dong Yang; Ruola Ning; Weixing Cai

    2009-01-01

    Flat panel detector-based cone beam breast CT (CBBCT) can provide 3D image of the scanned breast with 3D isotropic spatial resolution, overcoming the disadvantage of the structure superimposition associated with X-ray projection mammography. It is very difficult for Mammography to detect a small carcinoma (a few millimeters in size) when the tumor is occult or in dense breast. CBBCT featured with circular scan might be the most desirable mode in breast imaging due to its simple geometrical co...

  11. Nitrogen incorporated ultrananocrystalline diamond based field emitter array for a flat-panel x-ray source

    A field emission based flat-panel transmission x-ray source is being developed as an alternative for medical and industrial imaging. A field emitter array (FEA) prototype based on nitrogen incorporated ultrananocrystalline diamond film has been fabricated to be used as the electron source of this flat panel x-ray source. The FEA prototype was developed using conventional microfabrication techniques. The field emission characteristics of the FEA prototype were evaluated. Results indicated that emission current densities of the order of 6 mA/cm2 could be obtained at electric fields as low as 10 V/μm to 20 V/μm. During the prototype microfabrication process, issues such as delamination of the extraction gate and poor etching of the SiO2 insulating layer located between the emitters and the extraction layer were encountered. Consequently, alternative FEA designs were investigated. Experimental and simulation data from the first FEA prototype were compared and the results were used to evaluate the performance of alternative single and double gate designs that would yield better field emission characteristics compared to the first FEA prototype. The best simulation results are obtained for the double gate FEA design, when the diameter of the collimator gate is around 2.6 times the diameter of the extraction gate

  12. Dynamic modeling of the microalgae cultivation phase for energy production in open raceway ponds and flat panel photobioreactors

    Matteo eMarsullo

    2015-09-01

    Full Text Available A dynamic model of microalgae cultivation phase is presented in this work. Two cultivation technologies are taken into account: the open raceway pond and the flat panel photobioreactor. For each technology, the model is able to evaluate the microalgae areal and volumetric productivity and the energy production and consumption. Differently from the most common existing models in literature, which deal with a specific part of the overall cultivation process, the model presented here includes all physical and chemical quantities that mostly affect microalgae growth: the equation of the specific growth rate for the microalgae is influenced by CO2 and nutrients concentration in the water, light intensity, temperature of the water in the reactor and by the microalgae species being considered. All these input parameters can be tuned to obtain reliable predictions. A comparison with experimental data taken from the literature shows that the predictions are consistent, slightly overestimating the productivity in case of closed photobioreactor. The results obtained by the simulation runs are consistent with those found in literature, being the areal productivity for the open raceway pond between 50 and 70 t/(ha*year in Southern Spain (Sevilla and Brazil (Petrolina and between 250 and 350 t/(ha*year for the flat panel photobioreactor in the same locations.

  13. Experimental verification of ion range calculation in a treatment planning system using a flat-panel detector

    Telsemeyer, Julia; Ackermann, Benjamin; Ecker, Swantje; Jäkel, Oliver; Martišíková, Mária

    2014-07-01

    Heavy ion-beam therapy is a highly precise radiation therapy exploiting the characteristic interaction of ions with matter. The steep dose gradient of the Bragg curve allows the irradiation of targets with high-dose and a narrow dose penumbra around the target, in contrast to photon irradiation. This, however, makes heavy ion-beam therapy very sensitive to minor changes in the range calculation of the treatment planning system, as it has a direct influence on the outcome of the treatment. Our previous study has shown that ion radiography with an amorphous silicon flat-panel detector allows the measurement of the water equivalent thickness (WET) of an imaging object with good accuracy and high spatial resolution. In this study, the developed imaging technique is used to measure the WET distribution of a patient-like phantom, and these results are compared to the WET calculation of the treatment planning system. To do so, a measured two-dimensional map of the WET of an anthropomorphic phantom was compared to WET distributions based on x-ray computed tomography images as used in the treatment planning system. It was found that the WET maps agree well in the overall shape and two-dimensional distribution of WET values. Quantitatively, the ratio of the two-dimensional WET maps shows a mean of 1.004 with a standard deviation of 0.022. Differences were found to be concentrated at high WET gradients. This could be explained by the Bragg-peak degradation, which is measured in detail by ion radiography with the flat-panel detector, but is not taken into account in the treatment planning system. Excluding pixels exhibiting significant Bragg-peak degradation, the mean value of the ratio was found to be 1.000 with a standard deviation of 0.012. Employment of the amorphous silicon flat-panel detector for WET measurements allows us to detect uncertainties of the WET determination in the treatment planning process. This makes the investigated technique a very helpful tool to study

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

    We developed a cone-beam computed tomography (CBCT) system equipped with a large flat-panel detector. Data obtained by 200o 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

  15. Robot arm based flat panel CT-guided electromagnetic tracked spine interventions: phantom and animal model experiments

    Penzkofer, Tobias; Isfort, Peter; Bruners, Philipp; Mahnken, Andreas H. [RWTH Aachen University, Applied Medical Engineering, Helmholtz-Institute Aachen, Aachen (Germany); RWTH Aachen University, Department of Diagnostic Radiology, Aachen University Hospital, Aachen (Germany); Wiemann, Christian; Guenther, Rolf W. [RWTH Aachen University, Department of Diagnostic Radiology, Aachen University Hospital, Aachen (Germany); Kyriakou, Yiannis; Kalender, Willi A. [Friedrich-Alexander University of Erlangen-Nuremberg, Institute for Medical Physics, Erlangen (Germany); Schmitz-Rode, Thomas [RWTH Aachen University, Applied Medical Engineering, Helmholtz-Institute Aachen, Aachen (Germany)

    2010-11-15

    To evaluate accuracy and procedure times of electromagnetic tracking (EMT) in a robotic arm mounted flat panel setting using phantom and animal cadaveric models. A robotic arm mounted flat panel (RMFP) was used in combination with EMT to perform anthropomorphic phantom (n = 90) and ex vivo pig based punctures (n = 120) of lumbar facet joints (FJ, n = 120) and intervertebral discs (IVD, n = 90). Procedure accuracies and times were assessed and evaluated. FJ punctures were carried out with a spatial accuracy of 0.8 {+-} 0.9 mm (phantom) and 0.6 {+-} 0.8 mm (ex vivo) respectively. While IVD punctures showed puncture deviations of 0.6 {+-} 1.2 mm (phantom) and 0.5 {+-} 0.6 mm (ex vivo), direct and angulated phantom based punctures had accuracies of 0.8 {+-} 0.9 mm and 1.0 {+-} 1.3 mm. Planning took longer for ex vivo IVD punctures compared to phantom model interventions (39.3 {+-} 17.3 s vs. 20.8 {+-} 5.0 s, p = 0.001) and for angulated vs. direct phantom FJ punctures (19.7 {+-} 5.1 s vs. 28.6 {+-} 7.8 s, p < 0.001). Puncture times were longer for ex vivo procedures when compared to phantom model procedures in both FJ (37.9 {+-} 9.0 s vs. 23.6 {+-} 7.2 s, p = 0.001) and IVD punctures (43.9 {+-} 16.1 s vs. 31.1 {+-} 6.4 s, p = 0.026). The combination of RMFP with EMT provides an accurate method of navigation for spinal interventions such as facet joint punctures and intervertebral disc punctures. (orig.)

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

    Lim, Seong-Rin [Department of Chemical Engineering and Materials Science, University of California, 2017 Kemper Hall, One Shields Avenue, Davis, CA 95616 (United States); Schoenung, Julie M., E-mail: jmschoenung@ucdavis.edu [Department of Chemical Engineering and Materials Science, University of California, 2017 Kemper Hall, One Shields Avenue, Davis, CA 95616 (United States)

    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.

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

    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.

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

    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. PMID:11314093

  19. High-EPA Biomass from Nannochloropsis salina Cultivated in a Flat-Panel Photo-Bioreactor on a Process Water-Enriched Growth Medium

    Safafar, Hamed; Hass, Michael Z.; Møller, Per;

    2016-01-01

    of Nannochloropsis salina in laboratory scale when compared to algae cultivated in standard F/2 medium. Data from laboratory scale translated to the large scaleusing a 4000 L flat panel photo-bioreactor system. The algae growth rate in winter conditions in Denmark was slow, but results revealed that...

  20. Implementation of a program of quality assurance of image in an imaging system of flat panel portal; Puesta en marcha de un programa de garantia de calidad de imagen en un sistema de imagen portal de panel plano

    Gomez Barrado, A.; Sanchez Jimenez, E.; Benitez, J. A.; Sanchez-Reyes, A.

    2013-07-01

    (IGRT) image-guided radiation therapy is the one in which images are used to locate the area of treatment. Modern irradiation systems are equipped with different modalities for obtaining images, such as flat panel systems, systems conebeam, tomoimagen, etc. This paper describes the start-up and the experience of a quality assurance program based on a flat panel portal Imaging System. (Author)

  1. Active Matrix OLED Test Report

    Salazar, George

    2013-01-01

    This report focuses on the limited environmental testing of the AMOLED display performed as an engineering evaluation by The NASA Johnson Space Center (JSC)-specifically. EMI. Thermal Vac, and radiation tests. The AMOLED display is an active-matrix Organic Light Emitting Diode (OLED) technology. The testing provided an initial understanding of the technology and its suitability for space applications. Relative to light emitting diode (LED) displays or liquid crystal displays (LCDs), AMOLED displays provide a superior viewing experience even though they are much lighter and smaller, produce higher contrast ratio and richer colors, and require less power to operate than LCDs. However, AMOLED technology has not been demonstrated in a space environment. Therefore, some risks with the technology must be addressed before they can be seriously considered for human spaceflight. The environmental tests provided preliminary performance data on the ability of the display technology to handle some of the simulated induced space/spacecraft environments that an AMOLED display will see during a spacecraft certification test program. This engineering evaluation is part of a Space Act Agreement (SM) between The NASA/JSC and Honeywell International (HI) as a collaborative effort to evaluate the potential use of AMOLED technology for future human spaceflight missions- both government-led and commercial. Under this SM, HI is responsible for doing optical performance evaluation, as well as temperature and touch screen studies. The NASA/JSC is responsible for performing environmental testing comprised of EMI, Thermal Vac, and radiation tests. Additionally, as part of the testing, limited optical data was acquired to assess performance as the display was subjected to the induced environments. The NASA will benefit from this engineering evaluation by understanding AMOLED suitability for future use in space as well as becoming a smarter buyer (or developer) of the technology. HI benefits

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

    Zhao, Z. [Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21205 and Department of Biomedical Engineering, Tianjin University, Tianjin, China 300072 (China); Gang, G. J. [Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21205 and Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario M5G 2M9 (Canada); Siewerdsen, J. H., E-mail: jeff.siewerdsen@jhu.edu [Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21205 (United States); Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario M5G 2M9 (Canada); Department of Computer Science, Johns Hopkins University, Baltimore, Maryland 21205 (United States); Russell H. Morgan Department of Radiology, Johns Hopkins University, Baltimore, Maryland 21205 (United States)

    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

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

    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 (σQ), electronic noise (σE), and view aliasing (σview). Analysis included investigation of the noise, noise-power spectrum, and modulation transfer function as a function of the number of projections (Nproj), dose (Dtot), and voxel size (bvox). Results: The results reveal a nonmonotonic relationship between image noise andNproj at fixed total dose: for the CBCT system considered, noise decreased with increasing Nproj due to reduction of view sampling effects in the regime Nproj 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 β—and a general model of individual noise components (σQ, σE, and σview) demonstrated agreement with measurements over a broad range in Nproj, Dtot, and bvox. 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 rangeNproj ∼ 250–350, nearly an order of magnitude lower in Nproj than typical of multidetector CT, owing to the relatively high electronic noise in FPDs. The analysis explicitly relates view aliasing and quantum noise in a manner that includes aspects of the object (“clutter”) and imaging chain (including nonidealities of

  4. Cross Talk Study to the Single Photon Response of a Flat Panel PMT for the RICH Upgrade at LHCb

    Arnaboldi, C; Calvi, M; Fanchini, E; Gotti, C; Maino, M; Matteuzzi, C; Perego, D L; Pessina, G; Wang, J C

    2009-01-01

    The Ring Imaging CHerenkov, RICH, detector at LHCb is now readout by Hybrid Photon Detectors. In view of its upgrade a possible option is the adoption of the flat panel Photon Multipliers Tubes, PMT. An important issue for the good determination of the rings produced in the sensitive media is a negligible level of cross talk. We have experimentally studied the cross talk from the 64x64 pixels of the H9500 PMT from Hamamatsu. Results have shown that at the single photon signal level, as expected at LHCb, the statistics applied to the small number of electrons generated at the first dynode of the PMT chain leads to a cross talk mechanism that must be interpreted in term of the percentage of the number of induced signals rather than on the amplitude of the induced signals. The threshold to suppress cross talk must be increased to a significant fraction of the single photon signal for the worst case. The number of electrons generated at the first dynode is proportional to the biasing voltage. Measurements have sh...

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

    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. PMID:27041633

  6. High-resolution dynamic angiography using flat-panel volume CT: feasibility demonstration for neuro and lower limb vascular applications

    This paper evaluates a prototype flat-panel volume CT (fpVCT) for dynamic in vivo imaging in a variety of neurovascular and lower limb applications. Dynamic CTA was performed on 12 patients (neuro = 8, lower limb = 4) using an fpVCT with 120 kVp, 50 mA, rotation time varying from 8 to 19 s, and field of view of 25 x 25 x 18 cm3. Four-dimensional data sets (i.e. 3D images over time) were reconstructed and reviewed. Dynamic CTA demonstrated sufficient spatio-temporal resolution to elucidate first-pass and recirculation dynamics of contrast bolus through neurovasclar pathologies and phasic blood flow though lower-limb vasculature and grafts. The high spatial resolution of fpVCT resulted in reduced partial volume and metal beam-hardening artefacts. This facilitated assessment of vascular lumen in the presence of calcified plaque and evaluation of fractures, especially in the presence of fixation hardware. Evaluation of arteriovenous malformation using dynamic fpVCT angiography was of limited utility. Dynamic CTA using fpVCT can visualize time-varying phenomena in neuro and lower limb vascular applications and has sufficient diagnostic imaging quality to evaluate a number of pathologies affecting these regions. (orig.)

  7. X-ray flat panel detectors and X-ray tubes contributing to development of X-ray diagnostic systems

    X-ray flat panel detectors (FPDs) and X-ray tubes are key devices allowing X-ray diagnostic systems to support more sophisticated medical care. FPDs provide valuable information for the diagnosis of various diseases through the conversion of X-ray images of the human body into electronic signals, while X-ray tubes are used in a wide range of applications such as computed tomography (CT), angiography, fluoroscopy, mammography, and dental systems. Toshiba Electron Tubes and Devices Co., Ltd. has developed and commercialized FPDs providing high-quality diagnostic X-ray images with low dose exposure through the development of cutting-edge technologies including a fine crystal formation technology for cesium iodide (CsI) scintillators, thin-film transistor (TFT) arrays with photodiodes, and so on. In the field of X-ray tubes that can generate a high output of X-rays, we have developed a liquid metal hydrodynamic bearing (LM bearing) technology for various diagnostic systems including medical CT systems with a long lifetime and high rotation speed, and cardiovascular imaging systems with quiet operation. Furthermore, LM bearing technology reduces the burden on the environment by replacing insulating oil with water coolant for the cooling system and making the X-ray tubes more compact. (author)

  8. High-resolution dynamic angiography using flat-panel volume CT: feasibility demonstration for neuro and lower limb vascular applications

    Mehndiratta, Amit [Massachusetts General Hospital, Department of Radiology, Harvard Medical School, Boston, MA (United States); University of Oxford, Institute of Biomedical Engineering and Keble College, Oxford (United Kingdom); Indian Institute of Technology Delhi and All India Institute of Medical Science, Centre for Biomedical Engineering, New Delhi (India); Rabinov, James D. [Massachusetts General Hospital, Interventional Neuroradiology, Harvard Medical School, Boston, MA (United States); Grasruck, Michael [Siemens Medical Solutions, Forchheim (Germany); Liao, Eric C. [Massachusetts General Hospital, Department of Plastic and Reconstructive Surgery and Center for Regenerative Medicine, Harvard Medical School, Boston, MA (United States); Crandell, David [Spaulding Rehabilitation Hospital, Department of Physical Medicine and Rehabilitation, Harvard Medical School, Charlestown, MA (United States); Gupta, Rajiv [Massachusetts General Hospital, Department of Radiology, Harvard Medical School, Boston, MA (United States)

    2015-07-15

    This paper evaluates a prototype flat-panel volume CT (fpVCT) for dynamic in vivo imaging in a variety of neurovascular and lower limb applications. Dynamic CTA was performed on 12 patients (neuro = 8, lower limb = 4) using an fpVCT with 120 kVp, 50 mA, rotation time varying from 8 to 19 s, and field of view of 25 x 25 x 18 cm{sup 3}. Four-dimensional data sets (i.e. 3D images over time) were reconstructed and reviewed. Dynamic CTA demonstrated sufficient spatio-temporal resolution to elucidate first-pass and recirculation dynamics of contrast bolus through neurovasclar pathologies and phasic blood flow though lower-limb vasculature and grafts. The high spatial resolution of fpVCT resulted in reduced partial volume and metal beam-hardening artefacts. This facilitated assessment of vascular lumen in the presence of calcified plaque and evaluation of fractures, especially in the presence of fixation hardware. Evaluation of arteriovenous malformation using dynamic fpVCT angiography was of limited utility. Dynamic CTA using fpVCT can visualize time-varying phenomena in neuro and lower limb vascular applications and has sufficient diagnostic imaging quality to evaluate a number of pathologies affecting these regions. (orig.)

  9. Performance of a novel 43-cm x 43-cm flat-panel detector with CsI:Tl scintillator

    Yamazaki, Tatsuya; Tamura, Tomoyuki; Nokita, Makoto; Okada, Satoshi; Hayashida, Shinsuke; Ogawa, Yoshihiro

    2004-05-01

    We have developed a novel flat-panel detector with CsI:Tl scintillator. The detector consists of a single piece 43cm x 43cm amorphous silicon thin-film transistor (TFT) array with MIS (metal-insulator-semiconductor) photoelectric converter having a pixel pitch of 160μm coated with a needle-like crystal CsI:Tl scintillator. Signal chain was totally revised from current detector utilizing an innovative sensor technology. The novel detector and current detector were equipped to a digital radiography system allowing a quantitative and comparative study. Results show that the novel detector has a linear response covering the radiographic exposure range. It has a moderate modulation transfer function (MTF) sufficient to the radiography tasks and effective to suppress the aliasing. The detective quantum efficiency (DQE) was almost twice than the current detector. The result of contrast-detail phantom exposed with a 1/2x dose level is equivalent to that of current detector with a 1x dose level. These results show that performance of novel detector is superior to and expected to reduce the patient dose in half than current detector due to higher DQE and innovative sensor technology.

  10. Circle Plus Partial Helical Scan Scheme for a Flat Panel Detector-Based Cone Beam Breast X-Ray CT

    Dong Yang

    2009-01-01

    Full Text Available Flat panel detector-based cone beam breast CT (CBBCT can provide 3D image of the scanned breast with 3D isotropic spatial resolution, overcoming the disadvantage of the structure superimposition associated with X-ray projection mammography. It is very difficult for Mammography to detect a small carcinoma (a few millimeters in size when the tumor is occult or in dense breast. CBBCT featured with circular scan might be the most desirable mode in breast imaging due to its simple geometrical configuration and potential applications in functional imaging. An inherited large cone angle in CBBCT, however, will yield artifacts in the reconstruction images when only a single circular scan is employed. These artifacts usually manifest themselves as density drop and object geometrical distortion that are more noticeable in the reconstructed image areas that are further away from the circular scanning plane. In order to combat this drawback, a circle plus partial helical scan scheme is proposed. An exact circle plus straight line scan scheme is also conducted in computer simulation for the purpose of comparison. Computer simulations using a numerical breast phantom demonstrated the practical feasibility of this new scheme and correction to those artifacts to a certain degree.

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

    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

  12. Visualization of novel microstents in patients with unruptured intracranial aneurysms with contrast-enhanced flat panel detector CT

    Poncyljusz, Wojciech, E-mail: wponcyl@poczta.onet.pl [Departament of Interventional Radiology, Pomeranian Medical University, Neurointerventional Cath Lab MSW Hospital, Al. Powst. Wielkopolskich 72, 70-111 Szczecin (Poland); Zwarzany, Łukasz, E-mail: zwarzany@gmail.com [Departament of Interventional Radiology, Pomeranian Medical University, Neurointerventional Cath Lab MSW Hospital, Al. Powst. Wielkopolskich 72, 70-111 Szczecin (Poland); Safranow, Krzysztof, E-mail: chrissaf@mp.pl [Department of Biochemistry and Chemistry, Pomeranian Medical University, Al. Powst. Wielkopolskich 72, 70-111 Szczecin (Poland)

    2015-07-15

    Highlights: • We examine the feasibility of FPDCT for visualizing intracranial microstents. • Stent deployment and its apposition to the vessel wall are easily assessable. • Coil streaking artifacts hamper the assessment of stent visibility. - Abstract: Objectives: The aim of our study was to evaluate the feasibility of contrast-enhanced flat panel detector CT (FPDCT) for visualizing the novel microstents implanted in patients with unruptured wide-necked intracranial aneurysms. Methods: Forty-four cases of patients who underwent stent assisted coiling at our department were retrospectively analyzed. In each case, FPDCT images were performed after stent and coils deployment and then assessed in the terms of stent struts and all radiopaque markers and tantalum strands visibility separately using a 3-grade scale (1 – inadequate, 2 – good, 3 – excellent). Results: Stent struts visibility was assessed to be inadequate for evaluation in all cases. All radiopaque markers and tantalum strands visibility was excellent in 61.4% and good in 38.6% of cases. We observed 4 (9.09%) cases of incomplete stent opening. Treated aneurysm size <10 mm was an independent predictor of excellent stent all radiopaque markers and tantalum strands visibility (ρ = 0.014). Conclusions: Contrast-enhanced FPDCT is feasible for visualizing stents implanted in patients with intracranial aneurysms as it gives precise visualization of the relationships between the stent tantalum strands and the vessel wall. Stents used in the treatment of aneurysms ≥10 mm in size are worse visualized because of the coil streaking artifacts.

  13. Embedded nonvolatile memory devices with various silicon nitride energy band gaps on glass used for flat panel display applications

    Nonvolatile memory (NVM) devices with a nitride–nitride–oxynitride stack structure on a rough poly-silicon (poly-Si) surface were fabricated using a low-temperature poly-Si (LTPS) thin film transistor technology on glass substrates for application of flat panel display (FPD). The plasma-assisted oxidation/nitridation method is used to form a uniform oxynitride with an ultrathin tunneling layer on a rough LTPS surface. The NVMs, using a Si-rich silicon nitride film as a charge-trapping layer, were proposed as one of the solutions for the improvement of device performance such as the program/erase speed, the memory window and the charge retention characteristics. To further improve the vertical scaling and charge retention characteristics of NVM devices, the high-κ high-density N-rich SiNx films are used as a blocking layer. The fabricated NVM devices have outstanding electrical properties, such as a low threshold voltage, a high ON/OFF current ratio, a low subthreshold swing, a low operating voltage of less than ±9 V and a large memory window of 3.7 V, which remained about 1.9 V over a period of 10 years. These characteristics are suitable for electrical switching and data storage with in FPD application

  14. Development and evaluation of a portable amorphous silicon flat-panel x-ray detector

    Watanabe, Minoru; Mochizuki, Chiori; Kameshima, Toshio; Yamazaki, Tatsuya; Court, Laurence; Hayashida, Shinsuke; Morishita, Masakazu; Ohta, Shin-ichi

    2001-06-01

    The design, development and evaluation of a portable x-ray detector are described. The completed detector has a pixel pitch of 100 micrometers , an active imaging area of 22.5 x 27.5 cm2 (9 x 11 inch2), package outer dimensions of 32.5 x 32.5 cm2, a thickness of only 20 mm, and a weight of around 2.8 kg. A number of significant advances in the design and production processes were needed to produce such a compact detector with such a small pixel pitch, while maintaining the image quality achieved a current detector (CXDI-22) which has a 160 mm pixel pitch. These include the development of a low power readout IC, advances in detector packaging design, concentrating on lightweight and strong components, and redesign of the pixel structure to improve the fill-factor. A comparison is made of the imaging characteristics of this new detector with the CXDI-22 detector, and it is shown that the new detector demonstrates improved CTF, and NEQ. The new detector is also shown to demonstrate superior performance in a contrast-detail phantom evaluation. This new detector should be useful for limb and joint examinations as it offers high spatial resolution, combined with the same freedom in positioning provided by conventional screen-film cassettes.

  15. Enhanced solution velocity between dark and light areas with horizontal tubes and triangular prism baffles to improve microalgal growth in a flat-panel photo-bioreactor.

    Yang, Zongbo; Cheng, Jun; Xu, Xiaodan; Zhou, Junhu; Cen, Kefa

    2016-07-01

    Novel horizontal tubes and triangular prism (HTTP) baffles that generate flow vortices were developed to increase solution velocity between dark and light areas and thus improve microalgal growth in a flat-panel photo-bioreactor. Solution velocity, mass-transfer coefficient, and mixing time were measured with a particle-imaging velocimeter, dissolved oxygen probes, and pH probes. The solution mass-transfer coefficient increased by 30% and mixing time decreased by 21% when the HTTP baffles were used. The solution velocity between dark and light areas increased from ∼0.9cm/s to ∼3.5cm/s, resulting in a decreased dark-light cycle period to one-fourth. This enhanced flashing light effect with the HTTP baffles dramatically increased microalgae biomass yield by 70% in the flat-panel photo-bioreactor. PMID:27038260

  16. Clinical evaluation of digital angiographic system equipped with the Safire' flat-panel detector of a direct conversion type

    Miura, Yoshiaki; Miura, Yusuke; Goto, Keiichi [Shimadzu Corporation, Medical Systems Division, Research and Development, Kyoto (JP)] [and others

    2003-06-01

    This report presents a report on clinical evaluation of our newly developed flat-panel X-ray detector of a direct conversion type, designed to provide images of a resolution higher than, or at least equal to, that ensured by X-ray photographic films, in clinical digital X-ray cinematography. This new detector was named 'Safire' the acronym of 'Shimadzu advanced flat imaging receptor', emphasizing its high technological level, such as the capability to ensure high quality of images. The clinical evaluation of Shimadzu DIGITEX Premier digital angiography system, equipped with this new flat-panel X-ray detector of a direct conversion type, has been started in March, 2003, at the Kokura Memorial Hospital in Kyushu, Japan. (author)

  17. Digital radiography with a large-scale electronic flat-panel detector vs screen-film radiography: observer preference in clinical skeletal diagnostics

    The imaging performance of a recently developed digital flat-panel detector system was compared with conventional screen-film imaging in an observer preference study. In total, 34 image pairs of various regions of the skeleton were obtained in 24 patients; 30 image pairs were included in the study. The conventional images were acquired with 250- and 400-speed screen-film combinations, using the standard technique of our department. Within hours, the digital images were obtained using identical exposure parameters. The digital system employed a large-area (43 x 43 cm) flat-panel detector based on amorphous silicon (Trixell Pixium 4600), integrated in a Bucky table. Six radiologists independently evaluated the image pairs with respect to image latitude, soft tissue rendition, rendition of the periosteal and enosteal border of cortical bone, rendition of cancellous bone and the visibility of potentially present pathological changes, using a subjective five-point scale. The digital images were rated significantly (p=0.001) better than the screen-film images with respect to soft tissue rendition and image latitude. Also the rendition of the cancellous bone and the periosteal and enosteal border of the cortical bone was rated significantly (p=0.05) better for the flat-panel detector. The visibility of pathological lesions was equivalent; only large-area sclerotic lesions (n=2) were seen superiorly on screen-film images. The new digital flat-panel detector based on amorphous silicon appears to be at least equivalent to conventional screen-film combinations for skeletal examinations, and in most respects even superior. (orig.)

  18. Aplicación del Método de Monte Carlo en el Análisis de Materiales Utilizados en Detectores Flat Panel para Obtener Espectros de Rayos X.

    Pozuelo, Fausto; Querol Vives, Andrea; Gallardo Bermell, Sergio; Ródenas Diago, José; Verdú Martín, Gumersindo Jesús

    2013-01-01

    En este trabajo se propone el uso de un detector flat panel junto a una cuña de polimetilmetacrilato (PMMA) para estimar el espectro de rayos X utilizando el método de Monte Carlo y técnicas de reconstrucción. El código MCNP5 se ha utilizado para modelar distintos flat panel y obtener las curvas de dosis y las funciones respuesta del sistema. La mayor parte de los flat panel actuales utilizan materiales que presentan discontinuidades debidas al borde K en el coeficiente másico de absorción de...

  19. Volumetric cone-beam CT system based on a 41x41 cm2 flat-panel imager

    Jaffray, David A.; Siewerdsen, Jeffrey H.

    2001-06-01

    Cone-beam computed tomography (CBCT) based upon large-area flat-panel imager (FPI) technology is a flexible and adaptable technology that offers large field-of-view (FOV), high spatial resolution, and soft-tissue imaging. The imaging performance of FPI-based cone-beam CT has been evaluated on a computer-controlled bench-top system using an early prototype FPI with a small FOV (20.5 X 20.5 cm2). These investigations demonstrate the potential of this exciting technology. In this report, imaging performance is evaluated using a production grade large-area FPI (41 X 41 cm2) for which the manufacturer has achieved a significant reduction in additive noise. This reduction in additive noise results in a substantial improvement in detective quantum efficiency (DQE) at low exposures. The spatial resolution over the increased FOV of the cone-beam CT system is evaluated by imaging a fine steel wire placed at various locations within the volume of reconstruction. The measured modulation transfer function (MTF) of the system demonstrates spatial frequency pass beyond 1 mm-1 (10% modulation) with a slight degradation at points off the source plane. In addition to investigations of imaging performance, progress has also been made in the integration of this technology with a medical linear accelerator for on-line image-guided radiation therapy. Unlike the bench-top system, this implementation must contend with significant geometric non-idealities caused by gravity-induced flex of the x-ray tube and FPI support assemblies. A method of characterizing and correcting these non-idealities has been developed. Images of an anthropomorphic head phantom qualitatively demonstrate the excellent spatial resolution and large FOV achievable with the cone-beam approach in the clinical implementation.

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

    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

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

    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 surgical

  2. Semi-automatic classification of skeletal morphology in genetically altered mice using flat-panel volume computed tomography.

    Christian Dullin

    2007-07-01

    Full Text Available Rapid progress in exploring the human and mouse genome has resulted in the generation of a multitude of mouse models to study gene functions in their biological context. However, effective screening methods that allow rapid noninvasive phenotyping of transgenic and knockout mice are still lacking. To identify murine models with bone alterations in vivo, we used flat-panel volume computed tomography (fpVCT for high-resolution 3-D imaging and developed an algorithm with a computational intelligence system. First, we tested the accuracy and reliability of this approach by imaging discoidin domain receptor 2- (DDR2- deficient mice, which display distinct skull abnormalities as shown by comparative landmark-based analysis. High-contrast fpVCT data of the skull with 200 microm isotropic resolution and 8-s scan time allowed segmentation and computation of significant shape features as well as visualization of morphological differences. The application of a trained artificial neuronal network to these datasets permitted a semi-automatic and highly accurate phenotype classification of DDR2-deficient compared to C57BL/6 wild-type mice. Even heterozygous DDR2 mice with only subtle phenotypic alterations were correctly determined by fpVCT imaging and identified as a new class. In addition, we successfully applied the algorithm to classify knockout mice lacking the DDR1 gene with no apparent skull deformities. Thus, this new method seems to be a potential tool to identify novel mouse phenotypes with skull changes from transgenic and knockout mice on the basis of random mutagenesis as well as from genetic models. However for this purpose, new neuronal networks have to be created and trained. In summary, the combination of fpVCT images with artificial neuronal networks provides a reliable, novel method for rapid, cost-effective, and noninvasive primary screening tool to detect skeletal phenotypes in mice.

  3. Percutaneous sacroplasty with the use of C-arm flat-panel detector CT: technical feasibility and clinical outcome

    Kang, Sung Eun; Lee, Joon Woo; Kim, Joo Hyung; Kang, Heung Sik [Seoul National University Bundang Hospital, Department of Radiology, Gyeonggi-do (Korea, Republic of); Park, Kun Woo; Yeom, Jin S. [Seoul National University Bundang Hospital, Department of Orthopaedic Surgery, Gyeonggi-do (Korea, Republic of)

    2011-04-15

    Sacroplasty for sacral insufficiency fractures (SIFs) has been performed mostly under computed tomography (CT) or fluoroscopy guidance. The purposes of this study are to describe technical tips and clinical outcomes of sacroplasty under C-arm flat panel detector CT (C-arm CT) guidance, and to compare the cement distributions shown on C-arm CT with those on multi-detector CT (MDCT). This study consisted of patients who underwent sacroplasty for SIF using C-arm CT from May 2006 to May 2009. Technical success was assessed in terms of cement filling and leakage. Clinical outcome was assessed at short-term (less than 1 month) and long-term (more than 1 month) follow-up using a four-grade patient satisfaction scale: poor, fair, good, and excellent. After sacroplasty, all patients underwent MDCT and three radiologists compared MDCT images with C-arm CT images in consensus, focusing on the cement distribution and cement leakage. Sacroplasties were performed on both sacral alae in all 8 patients (male:female = 2:6, mean age = 76.9, range = 63-82). The technical success rate was 100%. At short-term follow up, 6 patients (87.5%) reported significant improvement. Five patients (62.5%) were available for long-term follow-up and all 5 patients reported a reduced pain and an improved ability to ambulate. Using MDCT as the standard of reference, the cement distribution was visualized equally well by C-arm CT. Sacroplasty under C-arm CT showed excellent technical success and good clinical outcome. There was an excellent correlation between C-arm CT and MDCT in evaluating cement distribution and cement leakage. (orig.)

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

    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. PMID:25045087

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

    Kenton, O; Valdes, G; Yin, L; Teo, B [The Hospital of the University of Pennsylvania, Philadelphia, PA (United States); Brousmiche, S; Wikler, D [Ion Beam Application, Louvain-la-neuve (Belgium)

    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.

  6. Amorphous selenium flat panel detectors for digital mammography: validation of a NPWE model observer with CDMAM observer performance experiments.

    Segui, Jennifer A; Zhao, Wei

    2006-10-01

    Model observers have been developed which incorporate a specific imaging task, system performance, and human observer characteristics and can potentially overcome some of the limitations in using detective quantum efficiency for optimization and comparison of detectors. In this paper, a modified nonprewhitening matched filter (NPWE) model observer was developed and validated to predict object detectability for an amorphous selenium (a-Se) direct flat-panel imager (FPI) where aliasing is severe. A preclinical a-Se digital mammography FPI with 85 microm pixel size was used in this investigation. Its physical imaging properties including modulation transfer function (MTF), noise power spectrum, and DQE were fully characterized. An observer performance study was conducted by imaging the CDMAM 3.4 contrast-detail phantom designed specifically for digital mammography and presenting these images to a panel of seven observers. X-ray attenuation and scatter due to the phantom were determined experimentally for use in development of the model observer. The observer study results were analyzed via threshold averaging and signal detection theory (SDT) based techniques to produce contrast-detail curves where threshold contrast is plotted as a function of disk diameter. Validity of the model was established using SDT analysis of the experimental data. The effect of aliasing on the detectability of small diameter disks was determined using the NPWE model observer. The signal spectrum was calculated using the presampling MTF of the detector with and without including the aliased terms. Our results indicate that the NPWE model based on Fourier domain parameters provides reasonable prediction of object detectability for the signal-known-exactly task in uniform image noise for a-Se direct FPI. PMID:17089837

  7. Amorphous selenium flat panel detectors for digital mammography: Validation of a NPWE model observer with CDMAM observer performance experiments

    Model observers have been developed which incorporate a specific imaging task, system performance, and human observer characteristics and can potentially overcome some of the limitations in using detective quantum efficiency for optimization and comparison of detectors. In this paper, a modified nonprewhitening matched filter (NPWE) model observer was developed and validated to predict object detectability for an amorphous selenium (a-Se) direct flat-panel imager (FPI) where aliasing is severe. A preclinical a-Se digital mammography FPI with 85 μm pixel size was used in this investigation. Its physical imaging properties including modulation transfer function (MTF), noise power spectrum, and DQE were fully characterized. An observer performance study was conducted by imaging the CDMAM 3.4 contrast-detail phantom designed specifically for digital mammography and presenting these images to a panel of seven observers. X-ray attenuation and scatter due to the phantom were determined experimentally for use in development of the model observer. The observer study results were analyzed via threshold averaging and signal detection theory (SDT) based techniques to produce contrast-detail curves where threshold contrast is plotted as a function of disk diameter. Validity of the model was established using SDT analysis of the experimental data. The effect of aliasing on the detectability of small diameter disks was determined using the NPWE model observer. The signal spectrum was calculated using the presampling MTF of the detector with and without including the aliased terms. Our results indicate that the NPWE model based on Fourier domain parameters provides reasonable prediction of object detectability for the signal-known-exactly task in uniform image noise for a-Se direct FPI

  8. Percutaneous sacroplasty with the use of C-arm flat-panel detector CT: technical feasibility and clinical outcome

    Sacroplasty for sacral insufficiency fractures (SIFs) has been performed mostly under computed tomography (CT) or fluoroscopy guidance. The purposes of this study are to describe technical tips and clinical outcomes of sacroplasty under C-arm flat panel detector CT (C-arm CT) guidance, and to compare the cement distributions shown on C-arm CT with those on multi-detector CT (MDCT). This study consisted of patients who underwent sacroplasty for SIF using C-arm CT from May 2006 to May 2009. Technical success was assessed in terms of cement filling and leakage. Clinical outcome was assessed at short-term (less than 1 month) and long-term (more than 1 month) follow-up using a four-grade patient satisfaction scale: poor, fair, good, and excellent. After sacroplasty, all patients underwent MDCT and three radiologists compared MDCT images with C-arm CT images in consensus, focusing on the cement distribution and cement leakage. Sacroplasties were performed on both sacral alae in all 8 patients (male:female = 2:6, mean age = 76.9, range = 63-82). The technical success rate was 100%. At short-term follow up, 6 patients (87.5%) reported significant improvement. Five patients (62.5%) were available for long-term follow-up and all 5 patients reported a reduced pain and an improved ability to ambulate. Using MDCT as the standard of reference, the cement distribution was visualized equally well by C-arm CT. Sacroplasty under C-arm CT showed excellent technical success and good clinical outcome. There was an excellent correlation between C-arm CT and MDCT in evaluating cement distribution and cement leakage. (orig.)

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

    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.

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

    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

  11. Trabecular structure analysis using C-arm CT: comparison with MDCT and flat-panel volume CT

    Phan, Catherine M.; Bredella, Miriam A.; Yoo, Albert J.; Hirsch, Joshua A.; Gupta, Rajiv [Massachusetts General Hospital Neuroradiology, Department of Radiology, Boston, MA (United States); Harvard Medical School, Boston, MA (United States); Macklin, Eric A. [Harvard Medical School, Boston, MA (United States); Massachusetts General Hospital, Biostatistics Center, Department of Medicine, Boston, MA (United States); Dadrich, Monica; Flechsig, Paul [German Cancer Research Center, Heidelberg (Germany)

    2011-08-15

    This paper assesses interscan, interreader, and intrareader variability of C-arm CT and compares it to that of flat-panel volume-CT (fpVCT) and high-definition multi-detector-CT (HD-MDCT). Five cadaver knee specimens were imaged using C-arm-CT, fpVCT, and HD-MDCT. Apparent (app.) trabecular bone volume fraction (BV/TV), app. trabecular number (TbN), app. trabecular spacing (TbSp), and app. trabecular thickness (TbTh) of the proximal tibia were measured by three readers. Interreader, intrareader, and interscan variability for C-arm CT was expressed as coefficient of variation (CV), standard deviation (SD), and intraclass correlation coefficient (ICC). With the exception of app.TbSp (CV: 7.05-9.35%, SD: 0.06-0.09, ICC: 0.89-0.94), the variability of C-arm CT was low (CV: 2.41-6.43%, SD: 0.01-0.048, ICC: 0.65-0.98). Its interreader reliability (CV: 2.66-4.55%, SD: 0.01-0.03, ICC: 0.81-0.95) was comparable to that of HD-MDCT (CV: 2.41-4.08%, SD: 0.014-0.016, ICC: 0.95-0.96), and fpVCT (CV: 3.13-5.63%, SD: 0.009-0.036, ICC: 0.64-0.98) for all parameters except app.TbSp. C-arm CT is a reliable method for assessing trabecular bone architectural parameters with the exception of app.TbSp due to spatial resolution limitation. (orig.)

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

    Siewerdsen, Jeffrey H., E-mail: jeff.siewerdsen@jhu.edu [Department of Biomedical Engineering, Johns Hopkins University, Traylor Building, Room 718, 720 Rutland Avenue, Baltimore, MD 21205 (United States)

    2011-08-21

    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 surgical

  13. Trabecular structure analysis using C-arm CT: comparison with MDCT and flat-panel volume CT

    This paper assesses interscan, interreader, and intrareader variability of C-arm CT and compares it to that of flat-panel volume-CT (fpVCT) and high-definition multi-detector-CT (HD-MDCT). Five cadaver knee specimens were imaged using C-arm-CT, fpVCT, and HD-MDCT. Apparent (app.) trabecular bone volume fraction (BV/TV), app. trabecular number (TbN), app. trabecular spacing (TbSp), and app. trabecular thickness (TbTh) of the proximal tibia were measured by three readers. Interreader, intrareader, and interscan variability for C-arm CT was expressed as coefficient of variation (CV), standard deviation (SD), and intraclass correlation coefficient (ICC). With the exception of app.TbSp (CV: 7.05-9.35%, SD: 0.06-0.09, ICC: 0.89-0.94), the variability of C-arm CT was low (CV: 2.41-6.43%, SD: 0.01-0.048, ICC: 0.65-0.98). Its interreader reliability (CV: 2.66-4.55%, SD: 0.01-0.03, ICC: 0.81-0.95) was comparable to that of HD-MDCT (CV: 2.41-4.08%, SD: 0.014-0.016, ICC: 0.95-0.96), and fpVCT (CV: 3.13-5.63%, SD: 0.009-0.036, ICC: 0.64-0.98) for all parameters except app.TbSp. C-arm CT is a reliable method for assessing trabecular bone architectural parameters with the exception of app.TbSp due to spatial resolution limitation. (orig.)

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

    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

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

    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.

  16. Comparison of image quality and radiation dose between an image-intensifier system and a newer-generation flat-panel detector system - technical phantom measurements and evaluation of clinical imaging in children

    Weis, Meike; Hagelstein, Claudia; Diehm, Theo; Schoenberg, Stefan O.; Neff, K.W. [University Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Institute of Clinical Radiology and Nuclear Medicine, Mannheim (Germany)

    2016-02-15

    Many image-intensifier fluoroscopy systems have been replaced by flat-panel detectors in recent years. To compare the level of contrast, image resolution and radiation dose between an image-intensifier and a newer-generation flat-panel detector system in a pediatric radiology unit. We compared two systems - a conventional image intensifier and a newer-generation flat-panel system. We measured image quality and radiation dose using a technical phantom. Additionally, we retrospectively compared age-matched fluoroscopic pediatric voiding cystourethrography (n = 15) and upper gastrointestinal investigations (n = 25). In phantom studies image contrast was equal while image resolution was higher and mean radiation dose lower using the flat-panel system (P < 0.0001). In pediatric investigations, mean dose area product was significantly reduced on the flat-panel system for upper gastrointestinal investigation (45 ± 38 μGy*m{sup 2} vs. 11 ± 9 μGy*m{sup 2}; P < 0.0001) and for voiding cystourethrography (18 ± 20 μGy*m{sup 2} vs. 10 ± 12 μGy*m{sup 2}; P = 0.04). The newer flat-panel system performs at lower dose levels with equal to better image quality and therefore seems to be the more suitable technique for pediatric fluoroscopy in comparison to image-intensifier systems. (orig.)

  17. Comparison of image quality and radiation dose between an image-intensifier system and a newer-generation flat-panel detector system - technical phantom measurements and evaluation of clinical imaging in children

    Many image-intensifier fluoroscopy systems have been replaced by flat-panel detectors in recent years. To compare the level of contrast, image resolution and radiation dose between an image-intensifier and a newer-generation flat-panel detector system in a pediatric radiology unit. We compared two systems - a conventional image intensifier and a newer-generation flat-panel system. We measured image quality and radiation dose using a technical phantom. Additionally, we retrospectively compared age-matched fluoroscopic pediatric voiding cystourethrography (n = 15) and upper gastrointestinal investigations (n = 25). In phantom studies image contrast was equal while image resolution was higher and mean radiation dose lower using the flat-panel system (P < 0.0001). In pediatric investigations, mean dose area product was significantly reduced on the flat-panel system for upper gastrointestinal investigation (45 ± 38 μGy*m2 vs. 11 ± 9 μGy*m2; P < 0.0001) and for voiding cystourethrography (18 ± 20 μGy*m2 vs. 10 ± 12 μGy*m2; P = 0.04). The newer flat-panel system performs at lower dose levels with equal to better image quality and therefore seems to be the more suitable technique for pediatric fluoroscopy in comparison to image-intensifier systems. (orig.)

  18. Performance of a 41x41 cm2 amorphous silicon flat panel x-ray detector designed for angiographic and R and F imaging applications

    We measured the physical imaging performance of a 41x41 cm2 amorphous silicon flat panel detector designed for angiographic and R and F imaging applications using methods from the emerging IEC standard for the measurement of detective quantum efficiency (DQE) in digital radiographic detectors. Measurements on 12 production detectors demonstrate consistent performance. The mean DQE at the detector center is about 0.77 at zero frequency and 0.27 at the Nyquist frequency (2.5 cycles/mm) when measured with a 7 mm of Al HVL spectrum at about 3.6 μGy. The mean MTF at the center of the detector for this spectrum is 0.24 at the Nyquist frequency. For radiographic operation all 2048x2048 detector elements are read out individually. For fluoroscopy, the detector operates in two 30 frame per second modes: either the center 1024x1024 detector elements are read out or the entire detector is read out with 2x2 pixel binning. A model was developed to predict differences in performance between the modes, and measurements demonstrate agreement with the model. Lag was measured using a quasi-equilibrium exposure method and was found to be 0.044 in the first frame and less than 0.007 after 1 s. We demonstrated that it is possible to use the lag data to correct for temporal correlation in images when measuring DQE with a fluoroscopic imaging technique. Measurements as a function of position on the detector demonstrate a high degree of uniformity. We also characterized dependences on spectrum, exposure level, and direction. Finally, we measured the DQE of a current state of the art image intensifier/CCD system using the same method as for the flat panel. We found the image intensifier system to have lower DQE than the flat panel at high exposure levels and approximately equivalent DQE at fluoroscopic levels

  19. The feasibility and clinical application of flat-panel detector computer tomography in evaluating cerebral blood volume: an initial prospective study

    Objective: To investigate the feasibility and clinical value of the determination of cerebral blood volume (CBV) map by using flat-panel detector computer tomography (FDCT) angiography system. Methods: A prospective self-control clinical trial was conducted in 20 patients with cerebral ischemia who were encountered during the period from June 2010 to March 2011. All the patients were diagnosed as cerebral ischemic diseases and were scheduled to take interventional procedures. All patients underwent cerebral perfusion computer tomography (PCT) and CBV map exam which was performed by flat-panel detector computer tomography (FDCT-CBV). The CBV values obtained by the two exam types were analyzed and compared with each other by using statistic methods. Results: All PCT and FDCT-CBV exams were successfully accomplished in all the twenty patients. A significant correlation existed between the CBV images and CBV values obtained by the two exam types. The correlation coefficient was 0.68 (P<0.01). The Bland-Altman analysis showed a mean difference of -0.25±2.79 between FDCT-CBV and PCT-CBV, indicating that FDCT-CBV values were only slightly lower than those of PCT-CBV. Conclusion: CBV exam by using flat-panel detector angiography system is clinically feasible and the results of FDCT-CBV is comparable to those of PCT-CBV. As the FDCT-CBV can offer functional images of the whole brain within the catheter lab, this technique is very helpful in making the reasonable operation plan and in improving the safety of endovascular procedures in neurosurgery. (authors)

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

    Mooslechner, Michaela; Mitterlechner, Bernhard; Weichenberger, Harald; Sedlmayer, Felix; Deutschmann, Heinz [Institute for Research and Development on Advanced Radiation Technologies (radART), Paracelsus Medical University, Salzburg 5020, Austria and University Clinic for Radiotherapy and Radio-Oncology, Landeskrankenhaus Salzburg, Paracelsus Medical University Clinics, Salzburg 5020 (Austria); Huber, Stefan [Institute for Research and Development on Advanced Radiation Technologies (radART), Paracelsus Medical University, Salzburg 5020 (Austria)

    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

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

    Zbijewski, W., E-mail: wzbijewski@jhu.edu; Gang, G. J.; Xu, J.; Wang, A. S.; Stayman, J. W. [Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21205 (United States); Taguchi, K.; Carrino, J. A. [Russell H. Morgan Department of Radiology, Johns Hopkins University, Baltimore, Maryland 21205 (United States); Siewerdsen, J. H. [Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21205 and Russell H. Morgan Department of Radiology, Johns Hopkins University, Baltimore, Maryland 21205 (United States)

    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

  2. A conformable active matrix LED display

    Tripathi, Ashutosh; Smits, Edsger; van der Steen, Jan-Laurens; Cauwe, Maarten; Verplancke, Rik; Myny, Kris; Maas, Joris; Kusters, Roel; Sabik, Sami; Murata, Mitsuhiro; Tomita, Yoshihiro; Ohmae, Hideki; van den Brand, Jeroen; Gelinck, Gerwin

    2015-01-01

    Conformable and stretchable displays can be integrated on complex surfaces. Such a display can assume the shape of a conformed surface by simultaneous multi-dimensional stretching and bending. Such technology provides new opportunities in the field of display applications, for example wearable displays integrated or embedded in a textile or onto complex surfaces in automotive interiors. In this work we present a conformable active matrix display using LEDs mounted on an amorphous Indium-Galli...

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

    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. PMID:21099176

  4. Impact of flat panel-imager veiling glare on scatter-estimation accuracy and image quality of a commercial on-board cone-beam CT imaging system

    Purpose: The purposes of this study is to measure the low frequency drop (LFD) of the modulation transfer function (MTF), associated with the long tails of the detector point spread function (PSF) of an on-board flat panel imager and study its impact on cone-beam CT (CBCT) image quality and scatter measurement accuracy. Methods: Two different experimental methods were used to characterize LFD and its associated PSF of a Varian OBI flat-panel detector system: the edge response function (ERF) method and the disk transfer function (DTF) method. PSF was estimated by fitting parametric models to these measurements for four values of the applied voltage (kVp). The resultant PSF was used to demonstrate the effect of LFD on image contrast and CT number accuracy in CBCT images reconstructed from synthetic datasets, as well as, accuracy of scatter measurements with the beam-stop method. Results: The MTFs derived from the measured ERF data revealed LFDs varying from 8% (at 60 kVp) to 10.5% (at 120 kVp), while the intensity of the long PSF tails was found to increase with increasing kVp. The veiling glare line spread functions derived from the ERF and DTF methods were in excellent agreement. Uncorrected veiling glare reduced contrast and the image intensity in CBCT reconstruction, near the phantom periphery (by 67 Hounsfield units in a 20 cm-in-diameter water phantom) and (to a smaller degree) near inhomogeneities. Use of the bow-tie filter mitigated these effects. Veiling glare also resulted in about 10%–15% overestimation of the scatter-to-primary ratio when measured with the beam-stop or beam-stop array method. Conclusions: The long tails of the detector PSF were found to have a modest dependence of beam spectrum, which is reflected on the MTF curve LFD. Our findings show that uncorrected veiling glare can affect quantitative accuracy and contrast in CBCT imaging, based on flat panel imager. In addition, it results in overestimation of the scatter-to-primary ratio

  5. Design of Thin-Film-Transistor (TFT) arrays using current mirror circuits for Flat Panel Detectors (FPDs)

    Salahuddin, Nur Sultan; Paindavoine, Michel; Huda, Nurul; Parmentier, Michel

    2011-01-01

    We designed 4x4 matrix TFTs arrays using current mirror amplifiers. Advantages of current mirror amplifiers are they need less requiring switches and the conversion time is short. The TFTs arrays 4x4 matrix using current mirror circuits have been fabricated and tested with success. The TFTs array directly can process signals coming from 16 pixels in the same node. This enables us to make the summation of the light intensities of close pixels during a reading.

  6. Dose performance evaluation of a charge coupled device and a flat-panel digital fluoroscopy system recently installed in an Interventional Cardiology laboratory

    The purpose of the study was to evaluate the dose performance of a flat-panel (FP) and an image intensifier (II) charge coupled device (CCD) digital fluoroscopy X-ray systems newly installed in an Interventional Cardiology (IC) department. Filter entrance dose rate, detector dose rate (during fluoroscopy) and filter entrance dose per image were measured at 70 cm from the focus using 2 mm copper sheets to mimic normal size patient. Image quality was also evaluated. The patient dose survey included 277 patients, which had either a Coronary Angiography (CA) or a Percutaneous Transluminal Coronary Angioplasty (PTCA). Dose area product (DAP), fluoroscopy time (T) and total number of frames (F) values were also collected. The results showed that both systems performed within international recommendations with the exception of higher cine radiation doses, stressing the fact that neither specific protocols of measurement nor reference values for digital equipment were provided by the official bodies. (authors)

  7. The physics of plasma-enhanced chemical vapour deposition for large-area coating: industrial application to flat panel displays and solar cells

    Perrin, Jerome [Unaxis-Balzers A.G., Central R and D, PO Box 1000, FL-9496 Balzers (Liechtenstein); Schmitt, Jacques [Unaxis-France S.A., Display Technology, 5 rue Leon Blum, F-91120, Palaiseau (France); Hollenstein, Christoph; Howling, Alan; Sansonnens, Laurent [Centre de Recherche en Physique des Plasmas, Ecole Polytechnique Federale de Lausanne, PPH Ecublens, CH - 1015 Lausanne (Switzerland)

    2000-12-01

    Designing plasma-enhanced chemical vapour deposition (PECVD) reactors to coat large-area glass plates ({approx}1 m{sup 2}) for flat panel display or solar cell manufacturing raises challenging issues in physics and chemistry as well as mechanical, thermal, and electrical engineering, and material science. In such reactive glow discharge plasma slabs, excited at RF frequency (from 13.56 MHz up to {approx}100 MHz), the thin-film deposition uniformity is determined by the gas flow distribution, as well as the RF voltage distribution along the electrodes, and by local plasma perturbations at the reactor boundaries. All these aspects can be approached by analytical and numerical modelling. Moreover, the film properties are largely determined by the plasma chemistry involving the neutral radicals contributing to film growth, the effect of ion bombardment, and the formation and trapping of dust triggered by homogeneous nucleation. This paper will review progress in this field, with particular emphasis on modelling developments. (author)

  8. The physics of plasma-enhanced chemical vapour deposition for large-area coating: industrial application to flat panel displays and solar cells

    Designing plasma-enhanced chemical vapour deposition (PECVD) reactors to coat large-area glass plates (∼1 m2) for flat panel display or solar cell manufacturing raises challenging issues in physics and chemistry as well as mechanical, thermal, and electrical engineering, and material science. In such reactive glow discharge plasma slabs, excited at RF frequency (from 13.56 MHz up to ∼100 MHz), the thin-film deposition uniformity is determined by the gas flow distribution, as well as the RF voltage distribution along the electrodes, and by local plasma perturbations at the reactor boundaries. All these aspects can be approached by analytical and numerical modelling. Moreover, the film properties are largely determined by the plasma chemistry involving the neutral radicals contributing to film growth, the effect of ion bombardment, and the formation and trapping of dust triggered by homogeneous nucleation. This paper will review progress in this field, with particular emphasis on modelling developments. (author)

  9. Radiation exposure to operating staff during rotational flat-panel angiography and C-arm cone beam computed tomography (CT) applications

    Purpose: To evaluate the radiation exposure for operating personel associated with rotational flat-panel angiography and C-arm cone beam CT. Materials and methods: Using a dedicated angiography-suite, 2D and 3D examinations of the liver were performed on a phantom to generate scattered radiation. Exposure was measured with a dosimeter at predefined heights (eye, thyroid, breast, gonads and knee) at the physician's location. Analysis included 3D procedures with a field of view (FOV) of 24 cm × 18 cm (8 s/rotation, 20 s/rotation and 5 s/2 rotations), and 47 cm × 18 cm (16 s/2 rotations) and standard 2D angiography (10 s, FOV 24 cm × 18 cm). Results: Measurements showed the highest radiation dose at the eye and thyroid level. In comparison to 2D-DSA (3.9 μSv eye-exposure), the 3D procedures caused an increased radiation exposure both in standard FOV (8 s/rotation: 28.0 μSv, 20 s/rotation: 79.3 μSv, 5 s/2 rotations: 32.5 μSv) and large FOV (37.6 μSv). Proportional distributions were measured for the residual heights. With the use of lead glass, irradiation of the eye lens was reduced to 0.2 μSv (2D DSA) and 10.6 μSv (3D technique with 20 s/rotation). Conclusion: Rotational flat-panel angiography and C-arm cone beam applications significantly increase radiation exposure to the attending operator in comparison to 2D angiography. Our study indicates that the physician should wear protective devices and leave the examination room when performing 3D examinations.

  10. The Usage of Flat Panel Solar Heater Balcony Style%平板式阳台壁挂太阳能应用浅析

    张子涵

    2014-01-01

    随着世界范围内的能源短缺和人们环保意识的增强,新能源和可再生能源技术将是21世纪世界经济发展中最具有决定性影响的技术领域之一,而太阳能作为取之不尽、生态学上纯净的和不改变地球上燃料平衡的能源,有着能源总量大,又容易实现小型化的优点,被认为是21世纪最重要的新能源。太阳能热水器将会成为改变人们生活的一大重要产品。平板式阳台壁挂太阳能成功解决了传统太阳能热水器安装中存在的瓶颈问题,成功实现了建筑一体化。本文就平板式阳台壁挂太阳能的应用方面做了一些探索研究。%Along with the shortage of energy and enhance of environment protection, renewable energy industry has become one of the most effective ones in the new century which can greatly affect people's life. As a clean and renewable energy, solar energy has been consid-ered as the most important new energy with the characteristics of renewable, endless and easy to reach. Flat panel solar heater greatly im-proved the traditional solar heaters shortcomings and realized the perfect combination with tal buildings. In this text, we have some study of the usage of flat panel solar heaters.

  11. The influence of liquid crystal display monitors on observer performance for the detection of interstitial lung markings on both storage phosphor and flat-panel-detector chest radiography

    Purpose: To compare observer performance with a flat-panel liquid crystal display (LCD) monitor and with a high-resolution gray-scale cathode ray tube (CRT) monitor in the detection of interstitial lung markings using a silicon flat-panel-detector direct radiography (DR) and storage phosphor computed radiography (CR) in a clinical setting. Materials and methods: We displayed 39 sets of posteroanterior chest radiographs from the patients who were suspected of interstitial lung disease. Each sets consisted of DR, CR and thin-section CT as the reference standard. Image identities were masked, randomly sorted, and displayed on both five mega pixel (2048 x 2560 x 8 bits) LCD and CRT monitors. Ten radiologists independently rated their confidence in detection for the presence of linear opacities in the four fields of the lungs; right upper, left upper, right lower, and left lower quadrant. Performance of a total 6240 (39 sets x 2 detector systems x 2 monitor system x 4 fields x 10 observers) observations was analyzed by multi-reader multi-case receiver operating characteristic (ROC) analysis. Differences between monitor systems in combinations of detector systems were compared using ANOVA and paired-samples t-test. Results: Area under curves (AUC) for the presence of linear opacities measured by ROC analysis was higher on the LCDs than CRTs without statistical significance (p = 0.082). AUC was significantly higher on the DR systems than CR systems (p = 0.006). AUC was significantly higher on the LCDs than CRTs for DR systems (p = 0.039) but not different for CR systems (p = 0.301). Conclusion: In clinical conditions, performance of the LCD monitor appears to be better for detecting interstitial lung markings when interfaced with DR systems.

  12. Radiation exposure to operating staff during rotational flat-panel angiography and C-arm cone beam computed tomography (CT) applications

    Schulz, Boris, E-mail: boris.schell@googlemail.com [Goethe University Hospital, Department of Diagnostic and Interventional Radiology, Theodor-Stern-Kai 7, 60590 Frankfurt (Germany); Heidenreich, Ralf, E-mail: ralf.heidenreich@roentgen-consult.de [Röntgen-Consult Company, Schulhausstrasse 37, 79199 Kirchzarten (Germany); Heidenreich, Monika, E-mail: info@roentgen-consult.de [Röntgen-Consult Company, Schulhausstrasse 37, 79199 Kirchzarten (Germany); Eichler, Katrin, E-mail: k.eichler@em.uni-frankfurt.de [Goethe University Hospital, Department of Diagnostic and Interventional Radiology, Theodor-Stern-Kai 7, 60590 Frankfurt (Germany); Thalhammer, Axel, E-mail: axel.thalhammer@kgu.de [Goethe University Hospital, Department of Diagnostic and Interventional Radiology, Theodor-Stern-Kai 7, 60590 Frankfurt (Germany); Naeem, Naguib Nagy Naguib, E-mail: nagynnn@yahoo.com [Goethe University Hospital, Department of Diagnostic and Interventional Radiology, Theodor-Stern-Kai 7, 60590 Frankfurt (Germany); Vogl, Thomas Josef, E-mail: T.Vogl@em.uni-frankfurt.de [Goethe University Hospital, Department of Diagnostic and Interventional Radiology, Theodor-Stern-Kai 7, 60590 Frankfurt (Germany); Zangos, Stefan, E-mail: Zangos@em.uni-frankfurt.de [Goethe University Hospital, Department of Diagnostic and Interventional Radiology, Theodor-Stern-Kai 7, 60590 Frankfurt (Germany)

    2012-12-15

    Purpose: To evaluate the radiation exposure for operating personel associated with rotational flat-panel angiography and C-arm cone beam CT. Materials and methods: Using a dedicated angiography-suite, 2D and 3D examinations of the liver were performed on a phantom to generate scattered radiation. Exposure was measured with a dosimeter at predefined heights (eye, thyroid, breast, gonads and knee) at the physician's location. Analysis included 3D procedures with a field of view (FOV) of 24 cm × 18 cm (8 s/rotation, 20 s/rotation and 5 s/2 rotations), and 47 cm × 18 cm (16 s/2 rotations) and standard 2D angiography (10 s, FOV 24 cm × 18 cm). Results: Measurements showed the highest radiation dose at the eye and thyroid level. In comparison to 2D-DSA (3.9 μSv eye-exposure), the 3D procedures caused an increased radiation exposure both in standard FOV (8 s/rotation: 28.0 μSv, 20 s/rotation: 79.3 μSv, 5 s/2 rotations: 32.5 μSv) and large FOV (37.6 μSv). Proportional distributions were measured for the residual heights. With the use of lead glass, irradiation of the eye lens was reduced to 0.2 μSv (2D DSA) and 10.6 μSv (3D technique with 20 s/rotation). Conclusion: Rotational flat-panel angiography and C-arm cone beam applications significantly increase radiation exposure to the attending operator in comparison to 2D angiography. Our study indicates that the physician should wear protective devices and leave the examination room when performing 3D examinations.

  13. Neutrophil activator of matrix metalloproteinase-2 (NAM).

    Rollo, Ellen E; Hymowitz, Michelle; Schmidt, Cathleen E; Montana, Steve; Foda, Hussein; Zucker, Stanley

    2006-01-01

    We have isolated a novel soluble factor(s), neutrophil activator of matrix metalloproteinases (NAM), secreted by unstimulated normal human peripheral blood neutrophils that causes the activation of cell secreted promatrix metalloproteinase-2 (proMMP-2). Partially purified preparations of NAM have been isolated from the conditioned media of neutrophils employing gelatin-Sepharose chromatography and differential membrane filter centrifugation. NAM activity, as assessed by exposing primary human umbilical vein endothelial cells (HUVEC) or HT1080 cells to NAM followed by gelatin zymography, was seen within one hour. Tissue inhibitor of metalloproteinase-2 (TIMP-2) and hydroxamic acid derived inhibitors of MMPs (CT1746 and BB94) abrogated the activation of proMMP-2 by NAM, while inhibitors of serine and cysteine proteases showed no effect. NAM also produced an increase in TIMP-2 binding to HUVEC and HT1080 cell surfaces that was inhibited by TIMP-2, CT1746, and BB94. Time-dependent increases in MT1-MMP protein and mRNA were seen following the addition of NAM to cells. These data support a role for NAM in cancer dissemination. PMID:17086359

  14. Difference in dose area product between analog image intensifier and digital flat panel detector in peripheral angiography and the effect of BMI

    Wiesinger, B.; Kirchner, S.; Schmehl, J.; Claussen, C.D. [Universitaetsklinikum Tuebingen (Germany). Diagnostische und Interventionelle Radiologie; Blumenstock, G. [Tuebingen Univ. (Germany). Inst. fuer Medizinische Biometrie; Herz, K. [Tuebingen Univ. (Germany). Inst. fuer Strahlenschutz und Isotopenlabor; Wiskirchen, J. [Franziskus Krankenhaus, Bielefeld (Germany). Radiologische Klinik

    2013-02-15

    Purpose: Comparison of dose area products (DAP) in diagnostic angiography procedures between an image intensifier (II) and a flat panel detector (FPD) angiography system and the evaluation of DAP/body mass index (BMI) dependency. Materials and Methods: An image intensifier system or a flat panel detector system was used to perform 571 diagnostic angiographies (n = 328 and n = 243, respectively) of 5 different types: peripheral arterial, venous, single leg, abdominal and upper extremity. The results were retrospectively analyzed. The DAP, fluoroscopy time (t) and the number of series of the respective interventions as calculated by the respective machines was compared for all interventions and for the respective subtypes and machines. The BMI dependency was calculated separately for both machines for all interventions by subdividing the patients into 6 BMI classes defined by the WHO. Results: The average DAP for all diagnostic interventions was 1958.9 cGy x cm{sup 2} (t = 384.6 s, n = 7.85 series) for the II and 2927.4 cGy x cm{sup 2} (t = 267.4 s, n = 7.02 series) for the FPD. Group-dependent differences ranged between + 21 and + 252 % when using the FPD system. After time standardization, the respective increases were found to be 120 % for the FPD system. The DAPs increased considerably in patients with higher BMIs (766.7 cGy x cm{sup 2} - 6892.6 cGy x cm{sup 2}, II machine, 950.5 cGy x cm{sup 2} - 12 487.7 cGy x cm{sup 2}, FPD machine) with a greater DAP gain seen for the FPD. The average duration of the interventions was higher using the II machine. Conclusion: The use of an FPD system led to higher DAP values compared to the II system in diagnostic angiographic procedures. In addition, increased BMI values led to higher DAPs, especially for the FPD machine. However, the average fluoroscopy times were shorter. (orig.)

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

    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

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

    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

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

    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. PMID:26325196

  18. Detectability of simulated pulmonary nodules on chest radiographs: Comparison between irradiation side sampling indirect flat-panel detector and computed radiography

    Objective: To compare the detectability of simulated pulmonary nodules on chest radiographs between an irradiation side sampling indirect flat-panel detector (ISS-FPD) and computed radiography (CR). Materials and methods: This study was an observer performance study. Simulated pulmonary nodules of 8 mm in diameter were superimposed on an anthropomorphic chest phantom. Chest radiographs were acquired under 2 exposure levels (4 and 3.2 mAs) with the ISS-FPD and the CR. Six thoracic radiologists evaluated all 40 images (10 patterns × 2 different exposure doses × 2 different systems) for the presence or absence of a lesion over each of 12 defined areas on a 3-megapixel monochrome liquid-crystal display. Receiver operating characteristic (ROC) curves were obtained for observation in predefined 480 areas. A jackknife method was used for statistical analysis. Differences with a P value of <0.05 were considered significant. Results: The analysis of the observer detection of simulated pulmonary nodules showed larger areas under the ROC curve (AUC) by the ISS-FPD than by the CR. There was a statistically significant difference between the two systems at 3.2 mAs (P = 0.0330). Conclusion: The ISS-FPD was superior to the CR for the detection of simulated pulmonary nodules at 3.2 mAs

  19. Comparison of Multidetector Computed Tomography and Flat-Panel Computed Tomography Regarding Visualization of Cortical Fractures, Cortical Defects, and Orthopedic Screws

    Neubauer, Jakob; Benndorf, Matthias; Lang, Hannah; Lampert, Florian; Kemna, Lars; Konstantinidis, Lukas; Neubauer, Claudia; Reising, Kilian; Zajonc, Horst; Kotter, Elmar; Langer, Mathias; Goerke, Sebastian M.

    2015-01-01

    Abstract To compare the visualization of cortical fractures, cortical defects, and orthopedic screws in a dedicated extremity flat-panel computed tomography (FPCT) scanner and a multidetector computed tomography (MDCT) scanner. We used feet of European roe deer as phantoms for cortical fractures, cortical defects, and implanted orthopedic screws. FPCT and MDCT scans were performed with equivalent dose settings. Six observers rated the scans according to number of fragments, size of defects, size of defects opposite orthopedic screws, and the length of different screws. The image quality regarding depiction of the cortical bone was assessed. The gold standard (real number of fragments) was evaluated by autopsy. The correlation of reader assessment of fragments, cortical defects, and screws with the gold standard was similar for FPCT and MDCT. Three readers rated the subjective image quality of the MDCT to be higher, whereas the others showed no preferences. Although the image quality was rated higher in the MDCT than in the FPCT by 3 out of 6 observers, both modalities proved to be comparable regarding the visualization of cortical fractures, cortical defects, and orthopedic screws and of use to musculoskeletal radiology regarding fracture detection and postsurgical evaluation in our experimental setting. PMID:26252281

  20. Comparison of Multidetector Computed Tomography and Flat-Panel Computed Tomography Regarding Visualization of Cortical Fractures, Cortical Defects, and Orthopedic Screws: A Phantom Study.

    Neubauer, Jakob; Benndorf, Matthias; Lang, Hannah; Lampert, Florian; Kemna, Lars; Konstantinidis, Lukas; Neubauer, Claudia; Reising, Kilian; Zajonc, Horst; Kotter, Elmar; Langer, Mathias; Goerke, Sebastian M

    2015-08-01

    To compare the visualization of cortical fractures, cortical defects, and orthopedic screws in a dedicated extremity flat-panel computed tomography (FPCT) scanner and a multidetector computed tomography (MDCT) scanner.We used feet of European roe deer as phantoms for cortical fractures, cortical defects, and implanted orthopedic screws. FPCT and MDCT scans were performed with equivalent dose settings. Six observers rated the scans according to number of fragments, size of defects, size of defects opposite orthopedic screws, and the length of different screws. The image quality regarding depiction of the cortical bone was assessed. The gold standard (real number of fragments) was evaluated by autopsy.The correlation of reader assessment of fragments, cortical defects, and screws with the gold standard was similar for FPCT and MDCT. Three readers rated the subjective image quality of the MDCT to be higher, whereas the others showed no preferences.Although the image quality was rated higher in the MDCT than in the FPCT by 3 out of 6 observers, both modalities proved to be comparable regarding the visualization of cortical fractures, cortical defects, and orthopedic screws and of use to musculoskeletal radiology regarding fracture detection and postsurgical evaluation in our experimental setting. PMID:26252281

  1. Experimental evaluation of a-Se and CdTe flat-panel x-ray detectors for digital radiography and fluoroscopy

    Adachi, Susumu; Hori, Naoyuki; Sato, Kenji; Tokuda, Satoshi; Sato, Toshiyuki; Uehara, Kazuhiro; Izumi, Yoshihiro; Nagata, Hisashi; Yoshimura, Youji; Yamada, Satoshi

    2000-04-01

    Described are two types of direct-detection flat-panel X-ray detectors utilizing amorphous selenium (a-Se) and cadmium telluride (CdTe). The a-Se detector is fabricated using direct deposition onto a thin film transistor (TFT) substrate, whereas the CdTe detector is fabricated using a novel hybrid method, in which CdTe is pre-deposited onto a glass substrate and then connected to a TFT substrate. The detector array format is 512 X 512 with a pixel pitch of 150 micrometer. The imaging properties of both detectors have been evaluated with respect to X-ray sensitivity, lag, spatial resolution, and detective quantum efficiency (DQE). The modulation transfer functions (MTFs) measured at 1 lp/mm were 0.96 for a- Se and 0.65 for CdTe. The imaging lags after 33 ms were about 4% for a-Se and 22% for CdTe. The DQE values measured at zero spatial frequency were 0.75 for a-Se and 0.22 for CdTe. The results indicate that the a-Se and CdTe detectors have high potential as new digital X-ray imaging devices for both radiography and fluoroscopy.

  2. Non-destructive, preclinical evaluation of root canal anatomy of human teeth with flat-panel detector volume CT (FD-VCT)

    Purpose: Successful endodontic diagnostics and therapy call for adequate depiction of the root canal anatomy with multimodal diagnostic imaging. The aim of the present study is to evaluate visualization of the endodont with flat-panel detector volume CT (FD-VCT). Materials and methods: 13 human teeth were examined with the prototype of a FD-VCT. After data acquisition and generation of volume data sets in volume rendering technology (VRT), the findings obtained were compared to conventional X-rays and cross-section preparations of the teeth. Results: The anatomical structures of the endodont such as root canals, side canals and communications between different root canals as well as dentricles could be detected precisely with FD-VCT. The length of curved root canals was also determined accurately. The spatial resolution of the system is around 140 μm. Only around 73% of the main root canals detected with FD-VCT and 87% of the roots could be visualized with conventional dental X-rays. None of the side canals, shown with FD-VCT, was detectable on conventional X-rays. In all cases the enamel and dentin of the teeth could be well delineated. No differences in image quality could be discerned between stored and freshly extracted teeth, or between primary and adult teeth. (orig.)

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

    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

  4. Cascaded-Systems Analysis of Flat-Panel Sandwich Detectors for Single-Shot Dual-Energy X-ray Imaging

    We have developed the cascaded-systems model to investigate the signal and noise characteristics in the flat-panel sandwich detector which was developed for the preclinical single-shot dual-energy x-ray imaging. The model incorporates parallel branches to include direct interaction of x-rays in photodiode that is unavoidable in the sandwich structure with a corresponding potential increase in image noise. The model has been validated in comparison with the experimental. The cascaded-systems analysis shows that direct x-ray interaction noise behaves as additive electronic noise that is white in the frequency domain; hence it is harmful to the DQE at higher frequencies where the number of secondary quanta lessens. Even at zero frequency, the direct x-ray interaction noise can reduce the DQE of the detectors investigated in this study by ∼20% for the 60 kV x-ray spectrum. The DQE of rear detector in the sandwich structure is sensitive to additive electronic noise because of the enhancement in the number of electronic noise quanta relative to that of x-ray quanta that are attenuated through the front layers including the intermediate filter layer (i.e. incident photon fluence times transmission factor)

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

    Wagner, Marlies, E-mail: marlies.wagner@kgu.de [Hospital of Goethe University, Institute of Neuroradiology (Germany); Kyriakou, Yiannis, E-mail: yiannis.kyriakou@siemens.com [Siemens AG, Health Care Sector (Germany); Mesnil de Rochemont, Richard du, E-mail: mesnil@em.uni-frankfurt.de [Hospital of Goethe University, Institute of Neuroradiology (Germany); Singer, Oliver C., E-mail: o.singer@em.uni-frankfurt.de [Hospital of Goethe University, Department of Neurology (Germany); Berkefeld, Joachim, E-mail: berkefeld@em.uni-frankfurt.de [Hospital of Goethe University, Institute of Neuroradiology (Germany)

    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.

  6. Cascaded-Systems Analysis of Flat-Panel Sandwich Detectors for Single-Shot Dual-Energy X-ray Imaging

    Kim, Ho Kyung; Kim, Dong Woon; Kim, Junwoo; Youn, Hanbean [Pusan National University, Busan (Korea, Republic of)

    2015-05-15

    We have developed the cascaded-systems model to investigate the signal and noise characteristics in the flat-panel sandwich detector which was developed for the preclinical single-shot dual-energy x-ray imaging. The model incorporates parallel branches to include direct interaction of x-rays in photodiode that is unavoidable in the sandwich structure with a corresponding potential increase in image noise. The model has been validated in comparison with the experimental. The cascaded-systems analysis shows that direct x-ray interaction noise behaves as additive electronic noise that is white in the frequency domain; hence it is harmful to the DQE at higher frequencies where the number of secondary quanta lessens. Even at zero frequency, the direct x-ray interaction noise can reduce the DQE of the detectors investigated in this study by ∼20% for the 60 kV x-ray spectrum. The DQE of rear detector in the sandwich structure is sensitive to additive electronic noise because of the enhancement in the number of electronic noise quanta relative to that of x-ray quanta that are attenuated through the front layers including the intermediate filter layer (i.e. incident photon fluence times transmission factor)

  7. Embedded LTPS flash cells with oxide-nitride-oxynitride stack structure for realization of multi-function mobile flat panel displays

    In this paper, embedded flash (eFlash) cells were fabricated for realization of multi-functions, such as systems on panels (SOPs) and threshold voltage (VTH) stabilization of flat panel displays (FPDs). Fabrication was via low temperature polycrystalline silicon (LTPS) thin film transistor (TFT) technology and an oxide-nitride-oxynitride (ONOn) stack structure on glass. Poly-silicon (poly-Si) on glass, which was annealed via an excimer laser, has a very rough surface. To fabricate LTPS eFlash cells on glass with a very rough poly-Si surface, plasma-assisted oxynitridation was performed; nitrous oxide (N2O) served as a reactive gas. LTPS eFlash cells have excellent TFT electrical properties, such as VTH, a high On/Off current ratio and a low sub-threshold swing (S). The results demonstrate that eFlash cells fabricated on glass with a rough silicon surface, via an ONOn stack structure, have switching characteristics suitable for data storage, such as a low operating voltage (TH, which exceeds 2.3 V, between the programming and erasing (P/E) states, over a period of 10 years, and the capacity to retain the initial ΔVTH over a period of 105 P/E operations. (fast track communication)

  8. Embedded LTPS flash cells with oxide-nitride-oxynitride stack structure for realization of multi-function mobile flat panel displays

    Jung, Sungwook; Kim, Jaehong; Son, Hyukjoo; Jang, Kyungsoo; Cho, Jaehyun; Kim, Kyunghae; Choi, Byoungdeog; Yi, Junsin [School of Information and Communication Engineering, Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of)], E-mail: yi@yurim.skku.ac.kr

    2008-09-07

    In this paper, embedded flash (eFlash) cells were fabricated for realization of multi-functions, such as systems on panels (SOPs) and threshold voltage (V{sub TH}) stabilization of flat panel displays (FPDs). Fabrication was via low temperature polycrystalline silicon (LTPS) thin film transistor (TFT) technology and an oxide-nitride-oxynitride (ONOn) stack structure on glass. Poly-silicon (poly-Si) on glass, which was annealed via an excimer laser, has a very rough surface. To fabricate LTPS eFlash cells on glass with a very rough poly-Si surface, plasma-assisted oxynitridation was performed; nitrous oxide (N{sub 2}O) served as a reactive gas. LTPS eFlash cells have excellent TFT electrical properties, such as V{sub TH}, a high On/Off current ratio and a low sub-threshold swing (S). The results demonstrate that eFlash cells fabricated on glass with a rough silicon surface, via an ONOn stack structure, have switching characteristics suitable for data storage, such as a low operating voltage (<{+-}10 V) suitable for mobile FPDs, a threshold voltage window, {delta}V{sub TH}, which exceeds 2.3 V, between the programming and erasing (P/E) states, over a period of 10 years, and the capacity to retain the initial {delta}V{sub TH} over a period of 10{sup 5} P/E operations. (fast track communication)

  9. A study on 100 MeV O7+ irradiated SnO2/Ag/SnO2 multilayer as transparent electrode for flat panel display application

    Sharma, Vikas; Singh, Satyavir; Asokan, K.; Sachdev, Kanupriya

    2016-07-01

    The multilayer thin films of SnO2/Ag/SnO2 were deposited using electron-beam and thermal evaporation for flat panel display application. The as-prepared SnO2/Ag/SnO2 specimen was irradiated with 100 MeV O7+ ions by varying the fluences 1 × 1012 and 5 × 1012 ions/cm2. The pristine and irradiated films were investigated using XRD, SEM, AFM and Raman to find out modification in the structure and surface morphology of the films. UV-Vis and Hall measurement techniques were used to investigate the optical and electrical properties respectively. It was observed that the roughness of the film after irradiation (for the fluence of 1 × 1012 ions/cm2) ​ decreased to 0.68 nm from 1.6 nm and showed an increase in roughness to 1.35 nm on increasing the fluence to 5 × 1012 ions/cm2. This oxide/metal/oxide structure fulfills the basic requirements of a TCE, like high-transmittance >75% for pristine and >80% for the fluence of 1 × 1012 ions/cm2 over a broad spectrum of visible light for practical applications. The multilayer structure shows change in the electrical resistivity from 1.6 × 10-3 Ω cm to 6.3 × 10-3 Ω cm after irradiation.

  10. The radioenzymatic assay of matrix metalloproteinase-1 activity

    The radioenzymatic assay method for tissue collagenase, a metalloproteinase, activity in matrix was established. The matrix collagenase is the most vital catabolic enzyme of collagen in tissue. It mainly acts on type- I, II, III matrix collagen and is also called matrix metalloproteinase-1 (MMPs-1). The assay method for the matrix collagenase was as follows: After type-I collagen was prepared from calf skin and identified with HPLC, it was marked with 3H-acetic anhydride as the substrate. Then a series of assays were performed in animal experiments and human cases, which showed that the matrix collagenase (MMPs-1) activity assay is feasible and gives reliable results in clinical biochemistry study

  11. The influence of antiscatter grids on soft-tissue detectability in cone-beam computed tomography with flat-panel detectors

    The influence of antiscatter x-ray grids on image quality in cone-beam computed tomography (CT) is evaluated through broad experimental investigation for various anatomical sites (head and body), scatter conditions (scatter-to-primary ratio (SPR) ranging from ∼10% to 150%), patient dose, and spatial resolution in three-dimensional reconstructions. Studies involved linear grids in combination with a flat-panel imager on a system for kilovoltage cone-beam CT imaging and guidance of radiation therapy. Grids were found to be effective in reducing x-ray scatter 'cupping' artifacts, with heavier grids providing increased image uniformity. The system was highly robust against ring artifacts that might arise in CT reconstructions as a result of gridline shadows in the projection data. The influence of grids on soft-tissue detectability was evaluated quantitatively in terms of absolute contrast, voxel noise, and contrast-to-noise ratio (CNR) in cone-beam CT reconstructions of 16 cm 'head' and 32 cm 'body' cylindrical phantoms. Imaging performance was investigated qualitatively in observer preference tests based on patient images (pelvis, abdomen, and head-and-neck sites) acquired with and without antiscatter grids. The results suggest that although grids reduce scatter artifacts and improve subject contrast, there is little strong motivation for the use of grids in cone-beam CT in terms of CNR and overall image quality under most circumstances. The results highlight the tradeoffs in contrast and noise imparted by grids, showing improved image quality with grids only under specific conditions of high x-ray scatter (SPR>100%), high imaging dose (Dcenter>2 cGy), and low spatial resolution (voxel size ≥1 mm)

  12. High-EPA Biomass from Nannochloropsis salina Cultivated in a Flat-Panel Photo-Bioreactor on a Process Water-Enriched Growth Medium.

    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

  13. High-EPA Biomass from Nannochloropsis salina Cultivated in a Flat-Panel Photo-Bioreactor on a Process Water-Enriched Growth Medium

    Hamed Safafar

    2016-07-01

    Full Text Available 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. Usefulness of DICOM headers in the analysis of two biplane X-ray systems setting (image intensifier and flat panel) used in pediatric interventional cardiology in Chile

    The setting of two biplane X ray systems were evaluated (image intensifier (II) and flat panel (PP)), through DICOM tags from 32 images created during the characterization of both systems. The technical parameters adjusted for systems were: 63,8 to 80,0 kV and 15,0 to 388,0 mA, for the system with II and 52,0 to 77,0 kV and 25,0 to 476,0 mA, for the system with PP detector. Both equipment presented a different mA adjustment, when moving from fluoroscopy modes low dose (FL), medium dose (FM) and high dose (FH) to cine mode (CI). Two dosimetric quantities were evaluated, the first one was the dose-area product (DAP) which gave as a result for FB mode, between 0,03 to 0,35 uGycm2/image (II) and from 0,05 a 0,69 uGycm2/image (PP), when the polymethyl methacrylate (PMMA) thickness was incremented from 4 to 16 cm. In cine mode the DAP quantity showed, percentage values from 24 to -1 % for the same PMMA increment. Skin cumulative dose was the second quantity evaluated and showed an increment of incident air kerma (KAI)/image in factors from 17 to 35 (II) and 15 to 28 (PP) when used in CI mode instead of FB mode, to the different PMMA thicknesses used. This dose increment for CI mode must be considered by cardiologists, to use the fluoroscopic run as an alternative to document part of the procedures when there is no need to use a high quality image (author)

  15. Design and construction of a flat-panel-based cone-beam computed tomography (FPD-CBCT) imaging system through the adaptation of a commercially available CT system: recent data

    Conover, David L.; Ning, Ruola

    2004-05-01

    The purpose of this presentation is to show how a commercially available spiral CT has been modified for use as the electro-mechanical scanner hardware for a prototype flat panel detector-based cone beam computed tomography (FPD-CBCT) imaging system. FPD-CBCT has the benefits of isotropic high resolution, low contrast sensitivity and 3D visualization. In contrast to spiral CT, which acquires a series of narrow slices, FPD-CBCT acquires a full volume of data (limited by the cone angle and the FPD active area) in one scan. Our goal was to use a GE HighSpeed Advantage (HSA) CT system as the basis for an FPD-CBVCT imaging prototype for performing phantom, animal and patient imaging studies. Specific electromechanical and radiographic subsystems controlled include: gantry rotation and tilt, patient table positioning, rotor control, mA control, the high frequency generator (kVp, exposure time, repetition rate) and image data acquisition. Also, a 2D full field FPD replaced the 1D detector, as well as the existing slit collimator was retrofitted to a full field collimator to allow x-ray exposure over the entire active area of the FPD. In addition, x-ray projection data was acquired at 30 fps. Power and communication signals to control modules on the rotating part of the gantry were transmitted through integrated slip rings on the gantry. A stationary host computer controlled mechanical motion of the gantry and sent trigger signals to on-board electronic interface modules to control data acquisition and radiographic functions. Acquired image data was grabbed to the system memory of an on-board industrial computer, saved to hard disk and downloaded through a network connection to the stationary computer for 3D reconstruction. Through the synchronized control of the pulsed x-ray exposures, data acquisition, and gantry rotation the system achieved a circle cone beam image acquisition protocol. With integrated control of the gantry tilt and of the position and translation speed

  16. TU-F-18C-02: Increasing Amorphous Selenium Thickness in Direct Conversion Flat-Panel Imagers for Contrast-Enhanced Dual-Energy Breast Imaging

    Scaduto, DA; Hu, Y-H; Zhao, W [Stony Brook University, Stony Brook, NY (United States)

    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

  17. The x-ray time of flight method for investigation of ghosting in amorphous selenium-based flat panel medical x-ray imagers

    Amorphous selenium (a-Se) based real-time flat-panel imagers (FPIs) are finding their way into the digital radiology department because they offer the practical advantages of digital x-ray imaging combined with an image quality that equals or outperforms that of conventional systems. The temporal imaging characteristics of FPIs can be affected by ghosting (i.e., radiation-induced changes of sensitivity) when the dose to the detector is high (e.g., portal imaging and mammography) or the images are acquired at a high frame rate (e.g., fluoroscopy). In this paper, the x-ray time-of-flight (TOF) method is introduced as a tool for the investigation of ghosting in a-Se photoconductor layers. The method consists of irradiating layers of a-Se with short x-ray pulses. From the current generated in the a-Se layer, ghosting is quantified and the ghosting parameters (charge carrier generation rate and carrier lifetimes and mobilities) are assessed. The x-ray TOF method is novel in that (1) x-ray sensitivity (S) and ghosting parameters can be measured simultaneously (2) the transport of both holes and electrons can be isolated, and (3) the method is applicable to the practical a-Se layer structure with blocking contacts used in FPIs. The x-ray TOF method was applied to an analysis of ghosting in a-Se photoconductor layers under portal imaging conditions, i.e., 1 mm thick a-Se layers, biased at 5 V/μm, were irradiated using a 6 MV LINAC x-ray beam to a total dose (ghosting dose) of 30 Gy. The initial sensitivity (S0) of the a-Se layers was 63±2 nC cm-2 cGy-1. It was found that S decreases to 30% of S0 after a ghosting dose of 5 Gy and to 21% after 30 Gy at which point no further change in S occurs. At an x-ray intensity of 22 Gy/s (instantaneous dose rate during a LINAC x-ray pulse), the charge carrier generation rate was 1.25±0.1x1022 ehp m-3 s-1 and, to a first approximation, independent of the ghosting dose. However, both hole and electron transport showed a strong

  18. Volume CT with a flat-panel detector on a mobile, isocentric C-arm: Pre-clinical investigation in guidance of minimally invasive surgery

    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 deg.), 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

  19. SU-E-I-11: Cascaded Linear System Model for Columnar CsI Flat Panel Imagers with Depth Dependent Gain and Blur

    Peng, B; Lubinsky, A; Zheng, H; Zhao, W [Stony Brook University, Stony Brook, NY (United States); Teymurazyan, A [Lakehead University, Thunder Bay, Ontario (Canada)

    2014-06-01

    Purpose: To implement a depth dependent gain and blur cascaded linear system model (CLSM) for optimizing columnar structured CsI indirect conversion flat panel imager (FPI) for advanced imaging applications. Methods: For experimental validation, depth dependent escape efficiency, e(z), was extracted from PHS measurement of different CsI scintillators (thickness, substrate and light output). The inherent MTF and DQE of CsI was measured using high resolution CMOS sensor. For CLSM, e(z) and the depth dependent MTF(f,z), were estimated using Monte Carlo simulation (Geant4) of optical photon transport through columnar CsI. Previous work showed that Monte Carlo simulation for CsI was hindered by the non-ideality of its columnar structure. In the present work we allowed variation in columnar width with depth, and assumed diffusive reflective backing and columns. Monte Carlo simulation was performed using an optical point source placed at different depth of the CsI layer, from which MTF(z,f) and e(z) were computed. The resulting e(z) with excellent matching with experimental measurements were then applied to the CLSM, Monte Carlo simulation was repeated until the modeled MTF, DQE(f) also match experimental measurement. Results: For a 150 micron FOS HL type CsI, e(z) varies between 0.56 to 0.45, and the MTF at 14 cycles/mm varies between 62.1% to 3.9%, from the front to the back of the scintillator. The overall MTF and DQE(f) at all frequencies are in excellent agreement with experimental measurements at all frequencies. Conclusion: We have developed a CLSM for columnar CsI scintillators with depth dependent gain and MTF, which were estimated from Monte Carlo simulation with novel optical simulation settings. Preliminary results showed excellent agreement between simulation results and experimental measurements. Future work is aimed at extending this approach to optimize CsI screen optic design and sensor structure for achieving higher DQE(f) in cone-beam CT, which uses

  20. COCHLEAR LENGTH DETERMINATION IN TEMPORAL BONE SPECIMENS USING HISTOLOGICAL SERIAL MICRO GRINDING IMAGING, MICRO COMPUTED TOMOGRAPHY AND FLAT-PANEL VOLUMETRIC COMPUTED TOMOGRAPHY

    Waldemar Würfel

    2015-04-01

    Full Text Available The cochlear length virtually describes the length of the cochlea in a straight line. Several theoretical options for measuring the length of the cochlea are conceivable. In choosing the type of cochlear implant electrode, this can play a crucial role. A wide range of electrodes is available, especially among the models designed to preserve residual hearing and structural integrity. It is believed that the depth of cochlear implant electrode insertion has an influence on the functional hearing based on the area of the cochlea that is electrically stimulated. Method: Imaging of nine human temporal bone specimens was performed using histological serial microgrinding imaging, micro computed tomography (microCT and experimental flat-panel volumetric computed tomography (fpVCT. Measurements were then performed by outlining the cochlea in OsiriX (Pixmeo, Los Angeles USA. Results: The cochlear length of 9 human temporal bones was determined in each histological serial microgrinding imaging, fpVCT and microCT. Cochlear length ranges in histological serial grinding imaging from 45.3 mm to 38.7 mm, in microCT from 46.1 mm to 39.3 mm and in fpVCT from 45.8 mm to 39.8 mm. Significant inter- and intraindividual differences in the cochlear length were observed. The presented methodology is capable of determining the cochlear length in each imaging modality. Discussion: A methodology to experimentally determine the cochlear length is interesting from both clinical and preclinical perspectives. Insertion studies are highly relevant to the development and evaluation of new electrode arrays. This study presents a measurement methodology that allows for individualized cochlear length measurement based on three established imaging modalities. The data presented here confirm differences in cochlear length. The method described here can be used to evaluate a cochlea in an experimental setting. This allows an individualized, pre-interventional evaluation of the

  1. 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

    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

  2. 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

    Vijayan, S; Rana, V; Nagesh, S Setlur; Xiong, Z; Rudin, S; Bednarek, D [Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY (United States)

    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.

  3. Shunt Active and Series Active Filters-Based Power Quality Conditioner for Matrix Converter

    P. Jeno Paul

    2011-01-01

    Full Text Available This paper proposes a series active filter and shunt active filter to minimize the power quality impact present in matrix converters instead of passive filter. A matrix converter produces significant harmonics and nonstandard frequency components into load. The proposed system compensates the sag and swell problems efficiently in matrix converter. The proposed system has been tested and validated on the matrix converter using MATLAB/Simulink software. Simulated results confirm that the active power filters can maintain high performance for matrix converter.

  4. Google matrix of the world network of economic activities

    Kandiah, Vivek; Escaith, Hubert; Shepelyansky, Dima L.

    2015-07-01

    Using the new data from the OECD-WTO world network of economic activities we construct the Google matrix G of this directed network and perform its detailed analysis. The network contains 58 countries and 37 activity sectors for years 1995 and 2008. The construction of G, based on Markov chain transitions, treats all countries on equal democratic grounds while the contribution of activity sectors is proportional to their exchange monetary volume. The Google matrix analysis allows to obtain reliable ranking of countries and activity sectors and to determine the sensitivity of CheiRank-PageRank commercial balance of countries in respect to price variations and labor cost in various countries. We demonstrate that the developed approach takes into account multiplicity of network links with economy interactions between countries and activity sectors thus being more efficient compared to the usual export-import analysis. The spectrum and eigenstates of G are also analyzed being related to specific activity communities of countries.

  5. 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

    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. (orig.)

  6. Daily quality control of collimator multi-leaf for IMRT static through flat panel (EPID); Control de calidad diario del colimador multilamina para IMRT estatica mediante panel plano (EPID)

    Gomez Barrado, A.; Benitez Serrano, J. A.; Sanchez Jimenez, E.; Sanchez-Reyes, A.

    2013-07-01

    When techniques are employed such as radiotherapy for intensity modulated (IMRT) is necessary to establish a proper quality assurance program. According to national and international recommendations, such a program must include, in addition to verification of treatment for each patient, a multi-leaf collimator quality control daily, easy to perform and analyze, to ensure the quality of the given treatments daily. This paper intends to make such quality control through the irradiation of a number of fields in the imaging system flat panel portal and its subsequent analysis. (Author)

  7. Experimental Investigation on Active Cooling for Ceramic Matrix Composite

    PENG Li-na; HE Guo-qiang; LIU Pei-jin

    2009-01-01

    Compared with conventional materials, the active cooling ceramic matrix composite used in ramjet or scramjet makes their structures lighter in mass and better in performance. In this paper, an active and a passive cooling refractory composite specimens are designed and tested with an experimental facility composed of multilayer smale scale cooling penel which consists of a water cooling system and a ceramic matrix composite specimen, and a gas generator used for providing lower and higher transfer rate gases to simulate the temperatures in combustion chamber of ramjst. The active cooling specimen can continuously suffer high surface temperature of 2 000K for 30s and that of 3 000 K for 9.3 s, respectively. The experiment results show that the active cooling composite structure is available for high-temperature condition in ramjet.

  8. Dose reduction of radiographs of the pediatric pelvis for diagnosing hip dysplasia using a digital flat-panel detector system; Dosisreduktion bei Roentgenaufnahmen des kindlichen Beckenskelettes zur Diagnostik der Hueftgelenksdysplasie unter Verwendung eines digitalen Flachdetektorsystems

    Ludwig, K.; Ahlers, K.; Kloska, S.; Vieth, V.; Meier, N.; Heindel, W. [Inst. fuer Klinische Radiologie, Westfaelische Wilhelms-Univ. Muenster (Germany); Sandmann, C.; Gosheger, G. [Orthopaedische Klinik, Westfaelische Wilhelms-Univ. Muenster (Germany)

    2003-01-01

    Purpose: To evaluate a possible dose reduction in pediatric pelvic radiographs in congenital hip dysplasia using a digital flat-panel system instead of a phosphor-storage system. Materials and Methods: During a six-month period, all pediatric patients referred for pelvic radiography for the evaluation of congenital hip dysplasia were randomely assigned to be examined by either a phosphor-storage system or a digital flat-panel system, whereby the latter system was operated with half the radiation dose. Thirty pairs of radiographs were assessed for the visibility of 16 anatomic details and for 5 orthopedic-radiographic measurements (5-point scale with 1 = excellent; three independent observers). The projection indices of Ball and Kommenda and of Toennis and Brunken were calculated for all radiographs. The Student's t-test was used to compare the flat-panel and the phosphor-storage radiographs for observers' assessments, patients' age and projection indices. Results: In a total of 7560 observations, the scores for the visibility of anatomic details and orthopedic-radiographic measurements were respectively 2.72 and 2.64 for the flat-panel system and 2.93 and 2.79 for the phosphor-storage system. No significant differences were found between both systems (p > 0.05) and between patient age and projection indices (p > 0.05). Conclusion: Pediatric pelvic radiographs can be obtained with a digital flat-panel system using half the radiation dose instead of a phosphor-storage system without sacrificing relevant information in the diagnosis of congenital hip dysplasia. (orig.) [German] Zielsetzung: Evaluation einer moeglichen Dosisreduktion bei kindlichen Beckenroentgenaufnahmen zur Diagnostik der Hueftgelenksdysplasie mit einem digitalen Flachdetektorsystem im Vergleich zu einem digitalen Speicherfoliensystem. Material und Methoden: Prospektiv wurden alle ueber einen Zeitraum von 6 Monaten zur Roentgenaufnahme des Beckenskelettes im Rahmen der Diagnostik der

  9. Extracellular Matrix Stiffness Regulates Osteogenic Differentiation through MAPK Activation.

    Jun-Ha Hwang

    Full Text Available Mesenchymal stem cell (MSC differentiation is regulated by the extracellular matrix (ECM through activation of intracellular signaling mediators. The stiffness of the ECM was shown to be an important regulatory factor for MSC differentiation, and transcriptional coactivator with PDZ-binding motif (TAZ was identified as an effector protein for MSC differentiation. However, the detailed underlying mechanism regarding the role of ECM stiffness and TAZ in MSC differentiation is not yet fully understood. In this report, we showed that ECM stiffness regulates MSC fate through ERK or JNK activation. Specifically, a stiff hydrogel matrix stimulates osteogenic differentiation concomitant with increased nuclear localization of TAZ, but inhibits adipogenic differentiation. ERK and JNK activity was significantly increased in cells cultured on a stiff hydrogel. TAZ activation was induced by ERK or JNK activation on a stiff hydrogel because exposure to an ERK or JNK inhibitor significantly decreased the nuclear localization of TAZ, indicating that ECM stiffness-induced ERK or JNK activation is important for TAZ-driven osteogenic differentiation. Taken together, these results suggest that ECM stiffness regulates MSC differentiation through ERK or JNK activation.

  10. Risk matrix model applied to the outsourcing of logistics' activities

    Fouad Jawab

    2015-09-01

    Full Text Available Purpose: This paper proposes the application of the risk matrix model in the field of logistics outsourcing. Such an application can serve as the basis for decision making regarding the conduct of a risk management in the logistics outsourcing process and allow its prevention. Design/methodology/approach: This study is based on the risk management of logistics outsourcing in the field of the retail sector in Morocco. The authors identify all possible risks and then classify and prioritize them using the Risk Matrix Model. Finally, we have come to four possible decisions for the identified risks. The analysis was made possible through interviews and discussions with the heads of departments and agents who are directly involved in each outsourced activity. Findings and Originality/value: It is possible to improve the risk matrix model by proposing more personalized prevention measures according to each company that operates in the mass-market retailing. Originality/value: This study is the only one made in the process of logistics outsourcing in the retail sector in Morocco through Label’vie as a case study. First, we had identified as thorough as we could all possible risks, then we applied the Risk Matrix Model to sort them out in an ascending order of importance and criticality. As a result, we could hand out to the decision-makers the mapping for an effective control of risks and a better guiding of the process of risk management.

  11. Readout electronics for multianode photomultiplier tubes with pad matrix anode layout

    We have developed economical readout concept for multianode photomultiplier tubes which have a matrix type pad anode layout. This style of anode layout is used in many position sensitive photomultiplier tubes such as R5900-M64 and recently available flat panel H8500 PMT from Hamamatsu Photonics, as well as the Burle PLANACO/spl trade/ 85011 PSPMT. All these PMTs have a matrix of 8/spl times/8 anode pads requiring signal readout from 64 outputs. The number of readout channels quickly increases in systems utilizing many of these PMTs. In order to reduce the number of active channels to be read we have employed a two-dimensional decoupling resistive matrix circuit. A decoupling resistive matrix was designed to convert the 2-D area readout into a projective two single coordinate readout, and, thereby, to simplify readout electronics. In the case of PMT array, the circuit permits ganging together signals from several of the photomultipliers in the same way as done in the cross-wire photomultiplier tube anode layout. We tested this readout concept in several compact gamma cameras designed and built at Jefferson Lab. The largest size array consists of 3/spl times/4 (12 total) of H8500 photomultiplier tubes with 768 individual anode pad outputs, which were decoupled into 32x+24y (56 total) readout channels, a reduction by factor - 14

  12. 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

    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. (orig.)

  13. 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

    Voelk, Markus; Hamer, Okka W.; Feuerbach, Stefan [Department of Diagnostic Radiology, University Hospital of Regensburg, Franz-Josef-Strauss-Allee 11, 93053, Regensburg (Germany); Strotzer, Michael [Department of Radiology, Hospital Hohe Warte, Hohe Warte 8, 95445, Bayreuth (Germany)

    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. (orig.)

  14. ELA-beam shaping systems for flat panel display prepared by LTPS%用于平板显示 LTPS制备的 ELA光束整形系统

    尹广玥; 游利兵; 方晓东

    2016-01-01

    介绍了多晶硅薄膜较非晶硅薄膜在平板显示领域的优势以及准分子激光晶化制备多晶硅膜的结晶过程。介绍了透镜阵列实现匀光的原理。阐述了典型的准分子激光退火线型光束整形系统的扩束、匀光、投影等结构。并介绍了连续横向固化技术在准分子激光制备低温多晶硅领域的应用。讨论了准分子激光退火光学系统的发展现状,指出了其在平板显示行业的重要意义。%The advantages to poly silicon film instead of amorphous silicon film in the field of flat panel display were introduced .Crystallization process of poly silicon film by using excimer laser crystallization system was studied .The principle of how lens array achieve the uniformity of output laser energy density was described .The structure of typical excimer laser annealing(ELA) line beam shaping system, which included beam expanding unit , beam energy homogenizing unit , projection unit and so on was focused on .Finally the application of sequential lateral solidification technology in the area of low temperature poly silicon ( LTPS ) using excimer laser nnealing was introduced .The status of ELA optical system was discussed and its significance in flat panel display industry was pointed out .

  15. Comparison between radiation exposure levels using an image intensifier and a flat-panel detector-based system in image-guided central venous catheter placement in children weighing less than 10 kg

    Miraglia, Roberto; Maruzzelli, Luigi; Cortis, Kelvin; Gerasia, Roberta; Maggio, Simona; Luca, Angelo [Diagnostic and Therapeutic Services, Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo (Italy); Piazza, Marcello [Department of Anesthesia, Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo (Italy); Tuzzolino, Fabio [Department of Information Technology, Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo (Italy)

    2014-09-10

    Ultrasound-guided central venous puncture and fluoroscopic guidance during central venous catheter (CVC) positioning optimizes technical success and lowers the complication rates in children, and is therefore considered standard practice. The purpose of this study was to compare the radiation exposure levels recorded during CVC placement in children weighing less than 10 kg in procedures performed using an image intensifier-based angiographic system (IIDS) to those performed in a flat-panel detector-based interventional suite (FPDS). A retrospective review of 96 image-guided CVC placements, between January 2008 and October 2013, in 49 children weighing less than 10 kg was performed. Mean age was 8.2 ± 4.4 months (range: 1-22 months). Mean weight was 7.1 ± 2.7 kg (range: 2.5-9.8 kg). The procedures were classified into two categories: non-tunneled and tunneled CVC placement. Thirty-five procedures were performed with the IIDS (21 non-tunneled CVC, 14 tunneled CVC); 61 procedures were performed with the FPDS (47 non-tunneled CVC, 14 tunneled CVC). For non-tunneled CVC, mean DAP was 113.5 ± 126.7 cGy cm{sup 2} with the IIDS and 15.9 ± 44.6 cGy . cm{sup 2} with the FPDS (P < 0.001). For tunneled CVC, mean DAP was 84.6 ± 81.2 cGy . cm{sup 2} with the IIDS and 37.1 ± 33.5 cGy cm{sup 2} with the FPDS (P = 0.02). The use of flat-panel angiographic equipment reduces radiation exposure in small children undergoing image-guided CVC placement. (orig.)

  16. Comparison between radiation exposure levels using an image intensifier and a flat-panel detector-based system in image-guided central venous catheter placement in children weighing less than 10 kg

    Ultrasound-guided central venous puncture and fluoroscopic guidance during central venous catheter (CVC) positioning optimizes technical success and lowers the complication rates in children, and is therefore considered standard practice. The purpose of this study was to compare the radiation exposure levels recorded during CVC placement in children weighing less than 10 kg in procedures performed using an image intensifier-based angiographic system (IIDS) to those performed in a flat-panel detector-based interventional suite (FPDS). A retrospective review of 96 image-guided CVC placements, between January 2008 and October 2013, in 49 children weighing less than 10 kg was performed. Mean age was 8.2 ± 4.4 months (range: 1-22 months). Mean weight was 7.1 ± 2.7 kg (range: 2.5-9.8 kg). The procedures were classified into two categories: non-tunneled and tunneled CVC placement. Thirty-five procedures were performed with the IIDS (21 non-tunneled CVC, 14 tunneled CVC); 61 procedures were performed with the FPDS (47 non-tunneled CVC, 14 tunneled CVC). For non-tunneled CVC, mean DAP was 113.5 ± 126.7 cGy cm2 with the IIDS and 15.9 ± 44.6 cGy . cm2 with the FPDS (P 2 with the IIDS and 37.1 ± 33.5 cGy cm2 with the FPDS (P = 0.02). The use of flat-panel angiographic equipment reduces radiation exposure in small children undergoing image-guided CVC placement. (orig.)

  17. Laminated active matrix organic light-emitting devices

    Liu, Hongyu; Sun, Runguang

    2008-02-01

    Laminated active matrix organic light-emitting device (AMOLED) realizing top emission by using bottom-emitting organic light-emitting diode (OLED) structure was proposed. The multilayer structure of OLED deposited in the conventional sequence is not on the thin film transistor (TFT) backplane but on the OLED plane. The contact between the indium tin oxide (ITO) electrode of TFT backplane and metal cathode of OLED plane is implemented by using transfer electrode. The stringent pixel design for aperture ratio of the bottom-emitting AMOLED, as well as special technology for the top ITO electrode of top-emitting AMOLED, is unnecessary in the laminated AMOLED.

  18. Matrix Metalloproteinase Activity in Pediatric Acute Lung Injury

    Michele YF Kong, Amit Gaggar, Yao Li, Margaret Winkler, J Edwin Blalock, JP Clancy

    2009-01-01

    Full Text Available Pediatric Acute Lung Injury (ALI is associated with a high mortality and morbidity, and dysregulation of matrix metalloproteinases (MMPs may play an important role in the pathogenesis and evolution of ALI. Here we examined MMP expression and activity in pediatric ALI compared with controls. MMP-8, -9, and to a lesser extent, MMP-2, -3, -11 and -12 were identified at higher levels in lung secretions of pediatric ALI patients compared with controls. Tissue Inhibitor of Matrix metalloproteinase-1 (TIMP-1, a natural inhibitor of MMPs was detected in most ALI samples, but MMP-9:TIMP-1 ratios were high relative to controls. In subjects who remained intubated for ≥10 days, MMP-9 activity decreased, with > 80% found in the latent form. In contrast, almost all MMP-8 detected at later disease course was constitutively active. Discriminating MMP-9:TIMP-1 ratios were found in those who had a prolonged ALI course. These results identify a specific repertoire of MMP isoforms in the lung secretions of pediatric ALI patients, and demonstrate inverse changes in MMPs -8 and -9 with protracted disease.

  19. Anacardic acid inhibits the catalytic activity of matrix metalloproteinase-2 and matrix metalloproteinase-9.

    Omanakuttan, Athira; Nambiar, Jyotsna; Harris, Rodney M; Bose, Chinchu; Pandurangan, Nanjan; Varghese, Rebu K; Kumar, Geetha B; Tainer, John A; Banerji, Asoke; Perry, J Jefferson P; Nair, Bipin G

    2012-10-01

    Cashew nut shell liquid (CNSL) has been used in traditional medicine for the treatment of a wide variety of pathophysiological conditions. To further define the mechanism of CNSL action, we investigated the effect of cashew nut shell extract (CNSE) on two matrix metalloproteinases, MMP-2/gelatinase A and MMP-9/gelatinase B, which are known to have critical roles in several disease states. We observed that the major constituent of CNSE, anacardic acid, markedly inhibited the gelatinase activity of 3T3-L1 cells. Our gelatin zymography studies on these two secreted gelatinases, present in the conditioned media from 3T3-L1 cells, established that anacardic acid directly inhibited the catalytic activities of both MMP-2 and MMP-9. Our docking studies suggested that anacardic acid binds into the MMP-2/9 active site, with the carboxylate group of anacardic acid chelating the catalytic zinc ion and forming a hydrogen bond to a key catalytic glutamate side chain and the C15 aliphatic group being accommodated within the relatively large S1' pocket of these gelatinases. In agreement with the docking results, our fluorescence-based studies on the recombinant MMP-2 catalytic core domain demonstrated that anacardic acid directly inhibits substrate peptide cleavage in a dose-dependent manner, with an IC₅₀ of 11.11 μM. In addition, our gelatinase zymography and fluorescence data confirmed that the cardol-cardanol mixture, salicylic acid, and aspirin, all of which lack key functional groups present in anacardic acid, are much weaker MMP-2/MMP-9 inhibitors. Our results provide the first evidence for inhibition of gelatinase catalytic activity by anacardic acid, providing a novel template for drug discovery and a molecular mechanism potentially involved in CNSL therapeutic action. PMID:22745359

  20. Establishment of action levels for quality control of IMRT flat panel: experience with the algorithm iGRiMLO; Establecimiento de niveles de accion para el control de calidad de IMRT con panel plano: experiencia con el algoritmo iGRiMLO

    Gonzalez, V.; Dolores, VV. de los; Pastor, V.; Martinez, J.; Gimeno, J.; Guardino, C.; Crispin, V.

    2011-07-01

    Algorithm has been used at our institution iGRiMLO scheduled for individual verification of treatment plans for intensity modulated radiotherapy (IMRT) step and shoot through portal dosimetry pretreatment of non-transmission, triggering the plan directly to a portal imaging device (EPID) of an amorphous silicon flat panel.

  1. Active-matrix polymer displays made with electroluminescent polymers

    Yu, Gang; Srdanov, Gordana; Zhang, Belinda; Stevenson, Matthew; Wang, Jian; Chen, Peter; Baggao, Erlinda; Macias, Johnny; Sun, Runguang; McPherson, Charlie; Sant, Paul; Innocenzo, Jeffrey; Stainer, Matthew; O'Regan, Marie B.

    2003-09-01

    Active-matrix organic/polyeric light emitting displays (AMOLEDs/AMPLEDs) are of great potentials for high information content display applications. They offer high brightness, fast response time, high image quality (high contrast, high gray levels and small pixel pitch size) and low power consumption. AMPLEDs are ideal for portable electronic devices such as web-phones, personal data assistants, GPS and handhold computers. AMPLEDs are especially suitable for motion picture applications. Since the image pixels consume power only when they are turned on, and only consume the power necessary for their corresponding brightness, video displays made with AMOLED/AMPLED reduce power consumption and extend display lifetime considerably. Motion picture applications also minimize image retention and optimize display homogeneity. In this presentation, we discuss our recent progress on AMPLEDs and compare their performance with that of AMLCD.

  2. Research on Field Emission Flat Panel Display Based on Carbon Nanotube%基于碳纳米管的场发射平板显示器研究

    王敏

    2014-01-01

    碳纳米管因具有良好的电子发射特性而成为理想的场发射阴极材料。本文概述了碳纳米管的特性、分类及制备;介绍了碳纳米管场发射平板显示器的结构、工作原理及制备,分析了碳纳米管场发射平板显示器的优缺点,针对其缺点提出了一些改进的思路并对其发展趋势作了展望。%Carbon nanotube is considered as an ideal ifeld emission cathode material for its good electron emission characteristic.This paper describes the characteristics,classiifcation and preparation of carbon nanotube,introduces the structure,working principle and preparation of carbon nanotube field emission flat panel display,analyzes the advantages and disadvantages of it,puts forward some improvement ideas,and prospects its development trend.

  3. Monolithic Active Pixel Matrix with Binary Counters (MAMBO) ASIC

    Khalid, Farah F.; Deptuch, Grzegorz; Shenai, Alpana; Yarema, Raymond J.; /Fermilab

    2010-11-01

    Monolithic Active Matrix with Binary Counters (MAMBO) is a counting ASIC designed for detecting and measuring low energy X-rays from 6-12 keV. Each pixel contains analogue functionality implemented with a charge preamplifier, CR-RC{sup 2} shaper and a baseline restorer. It also contains a window comparator which can be trimmed by 4 bit DACs to remove systematic offsets. The hits are registered by a 12 bit ripple counter which is reconfigured as a shift register to serially output the data from the entire ASIC. Each pixel can be tested individually. Two diverse approaches have been used to prevent coupling between the detector and electronics in MAMBO III and MAMBO IV. MAMBO III is a 3D ASIC, the bottom ASIC consists of diodes which are connected to the top ASIC using {mu}-bump bonds. The detector is decoupled from the electronics by physically separating them on two tiers and using several metal layers as a shield. MAMBO IV is a monolithic structure which uses a nested well approach to isolate the detector from the electronics. The ASICs are being fabricated using the SOI 0.2 {micro}m OKI process, MAMBO III is 3D bonded at T-Micro and MAMBO IV nested well structure was developed in collaboration between OKI and Fermilab.

  4. AMOLED (active matrix OLED) functionality and usable lifetime at temperature

    Fellowes, David A.; Wood, Michael V.; Prache, Olivier; Jones, Susan

    2005-05-01

    Active Matrix Organic Light Emitting Diode (AMOLED) displays are known to exhibit high levels of performance, and these levels of performance have continually been improved over time with new materials and electronics design. eMagin Corporation developed a manually adjustable temperature compensation circuit with brightness control to allow for excellent performance over a wide temperature range. Night Vision and Electronic Sensors Directorate (US Army) tested the performance and survivability of a number of AMOLED displays in a temperature chamber over a range from -55°C to +85°C. Although device performance of AMOLEDs has always been its strong suit, the issue of usable display lifetimes for military applications continues to be an area of discussion and research. eMagin has made improvements in OLED materials and worked towards the development of a better understanding of usable lifetime for operation in a military system. NVESD ran luminance degradation tests of AMOLED panels at 50°C and at ambient to characterize the lifetime of AMOLED devices. The result is a better understanding of the applicability of AMOLEDs in military systems: where good fits are made, and where further development is needed.

  5. Anacardic Acid Inhibits the Catalytic Activity of Matrix Metalloproteinase-2 and Matrix Metalloproteinase-9

    Omanakuttan, Athira; Nambiar, Jyotsna; Harris, Rodney M.; Bose, Chinchu; Pandurangan, Nanjan; Varghese, Rebu K.; Kumar, Geetha B.; Tainer, John A; Banerji, Asoke; Perry, J. Jefferson P.; Nair, Bipin G

    2012-01-01

    Cashew nut shell liquid (CNSL) has been used in traditional medicine for the treatment of a wide variety of pathophysiological conditions. To further define the mechanism of CNSL action, we investigated the effect of cashew nut shell extract (CNSE) on two matrix metalloproteinases, MMP-2/gelatinase A and MMP-9/gelatinase B, which are known to have critical roles in several disease states. We observed that the major constituent of CNSE, anacardic acid, markedly inhibited the gelatinase activit...

  6. Increase of brightness and transmission efficiency in flat panel display through serial synchronous scanning mode with double buffers%串行同步双缓冲扫描提高平板显示器的显示亮度和传送利用率

    陈章进; 陈峰; 冉峰; 徐美华; 郑方

    2007-01-01

    This paper presents a serial synchronous scanning mode in flat panel display(FPD)by adding a latch buffer between the seriaiizer and the driving buffer.Comparing with conventional techniques,the proposed structure can efficiently reduce the brightness loss and improve the transmission performance.Theoretical analysis and experimental results show that the ratio between the lightest weight display time and the relative transmission time is a tradeoff between brightness loss and transmission efficiency.

  7. Flat-Panel Cone-Beam Ct-Guided Radiofrequency Ablation of Very Small (≤1.5 cm) Liver Tumors: Technical Note on a Preliminary Experience

    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

  8. Flat-Panel Cone-Beam Ct-Guided Radiofrequency Ablation of Very Small (≤1.5 cm) Liver Tumors: Technical Note on a Preliminary Experience

    Cazzato, Roberto Luigi, E-mail: r.cazzato@unicampus.it; Buy, Xavier, E-mail: x.buy@bordeaux.unicancer.fr; Alberti, Nicolas, E-mail: nicoalbertibdx@gmail.com; Fonck, Mariane, E-mail: m.fonk@bordeaux.unicancer.fr [Institut Bergonié 229 Cours de l’Argonne, Department of Radiology (France); Grasso, Rosario Francesco, E-mail: r.grasso@unicampus.it [Università “Campus Bio-Medico di Roma”, Department of Radiology and Diagnostic Imaging (Italy); Palussière, Jean, E-mail: j.palussiere@bordeaux.unicancer.fr [Institut Bergonié 229 Cours de l’Argonne, Department of Radiology (France)

    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.

  9. 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

    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

  10. 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

    Miraglia, Roberto, E-mail: rmiraglia@ismett.edu; Maruzzelli, Luigi [Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Department of Diagnostic and Interventional Radiology (Italy); Tuzzolino, Fabio [Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Department of Information Technology (Italy); Indovina, Pietro Luigi [Medical Physic ISMETT Consultant, Fismeco (Italy); Luca, Angelo [Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Department of Diagnostic and Interventional Radiology (Italy)

    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.