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Sample records for c-arm flat detector

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

    Energy Technology Data Exchange (ETDEWEB)

    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.)

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

    International Nuclear Information System (INIS)

    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.)

  3. Low dose, low noise, and high resolution volume of interest (VOI) imaging in C-arm flat-detector CT

    Science.gov (United States)

    Kolditz, Daniel; Kyriakou, Yiannis; Kalender, Willi A.

    2010-04-01

    The high flexibility of C-arm flat-detector computed tomography (FDCT) is used in a volume of interest (VOI) imaging method to handle the challenges of increasing spatial resolution, reducing noise and saving dose. A low-dose overview scan of the object and a high-dose scan of an arbitrary VOI are combined. The first scan is adequate for orientation to select the VOI and the second scan assures high image quality in the VOI. The combination is based on a forward projection of the reconstructed overview volume and the measured VOI data in the raw data domain. Differences in the projection values are matched before a standard Feldkamp-type reconstruction is performed. In simulations, spatial resolution, noise and contrast detectability were evaluated. Measurements of an anthropomorphic phantom were used to validate the proposed method for realistic application. In Monte Carlo dose simulations the dose reduction potential was investigated. By combination of the two scans an image is generated which covers the whole object and provides the actual VOI at high image quality. Spatial resolution was increased whereas noise was decreased from outside to inside the VOI, e.g. for the simulations from 0.8 lp/mm to 3.0 lp/mm and from 39 HU to 18 HU, respectively. Simultaneously, the cumulative dose for this two-scan procedure was significantly reduced in comparison to a conventional high dose scan, e.g. for the performed simulations and measurements by about 95 %. The proposed VOI approach offers significant benefits with respect to high-resolution and low-contrast imaging of a VOI at reduced dose.

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

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    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.

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

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    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.

  7. Comparison of extended field-of-view reconstructions in C-arm flat-detector CT using patient size, shape or attenuation information

    Energy Technology Data Exchange (ETDEWEB)

    Kolditz, Daniel; Meyer, Michael; Kyriakou, Yiannis; Kalender, Willi A, E-mail: daniel.kolditz@imp.uni-erlangen.d [Institute of Medical Physics, University of Erlangen-Nuernberg (Germany)

    2011-01-07

    In C-arm-based flat-detector computed tomography (FDCT) it frequently happens that the patient exceeds the scan field of view (SFOV) in the transaxial direction because of the limited detector size. This results in data truncation and CT image artefacts. In this work three truncation correction approaches for extended field-of-view (EFOV) reconstructions have been implemented and evaluated. An FDCT-based method estimates the patient size and shape from the truncated projections by fitting an elliptical model to the raw data in order to apply an extrapolation. In a camera-based approach the patient is sampled with an optical tracking system and this information is used to apply an extrapolation. In a CT-based method the projections are completed by artificial projection data obtained from the CT data acquired in an earlier exam. For all methods the extended projections are filtered and backprojected with a standard Feldkamp-type algorithm. Quantitative evaluations have been performed by simulations of voxelized phantoms on the basis of the root mean square deviation and a quality factor Q (Q = 1 represents the ideal correction). Measurements with a C-arm FDCT system have been used to validate the simulations and to investigate the practical applicability using anthropomorphic phantoms which caused truncation in all projections. The proposed approaches enlarged the FOV to cover wider patient cross-sections. Thus, image quality inside and outside the SFOV has been improved. Best results have been obtained using the CT-based method, followed by the camera-based and the FDCT-based truncation correction. For simulations, quality factors up to 0.98 have been achieved. Truncation-induced cupping artefacts have been reduced, e.g., from 218% to less than 1% for the measurements. The proposed truncation correction approaches for EFOV reconstructions are an effective way to ensure accurate CT values inside the SFOV and to recover peripheral information outside the SFOV.

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

    International Nuclear Information System (INIS)

    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

  9. C-arm flat detector computed tomography parenchymal blood volume imaging: the nature of parenchymal blood volume parameter and the feasibility of parenchymal blood volume imaging in aneurysmal subarachnoid haemorrhage patients

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    Kamran, Mudassar; Byrne, James V. [University of Oxford, Nuffield Department of Surgical Sciences, Oxford (United Kingdom)

    2015-09-15

    C-arm flat detector computed tomography (FDCT) parenchymal blood volume (PBV) measurements allow assessment of cerebral haemodynamics in the neurointerventional suite. This paper explores the feasibility of C-arm computed tomography (CT) PBV imaging and the relationship between the C-arm CT PBV and the MR-PWI-derived cerebral blood volume (CBV) and cerebral blood flow (CBF) parameters in aneurysmal subarachnoid haemorrhage (SAH) patients developing delayed cerebral ischemia (DCI). Twenty-six patients with DCI following aneurysmal SAH underwent a research C-arm CT PBV scan using a biplane angiography system and contemporaneous MR-PWI scan as part of a prospective study. Quantitative whole-brain atlas-based volume-of-interest analysis in conjunction with Pearson correlation and Bland-Altman tests was performed to explore the agreement between C-arm CT PBV and MR-derived CBV and CBF measurements. All patients received medical management, while eight patients (31 %) underwent selective intra-arterial chemical angioplasty. Colour-coded C-arm CT PBV maps were 91 % sensitive and 100 % specific in detecting the perfusion abnormalities. C-arm CT rPBV demonstrated good agreement and strong correlation with both MR-rCBV and MR-rCBF measurements; the agreement and correlation were stronger for MR-rCBF relative to MR-rCBV and improved for C-arm CT PBV versus the geometric mean of MR-rCBV and MR-rCBF. Analysis of weighted means showed that the C-arm CT PBV has a preferential blood flow weighting (∼60 % blood flow and ∼40 % blood volume weighting). C-arm CT PBV imaging is feasible in DCI following aneurysmal SAH. PBV is a composite perfusion parameter incorporating both blood flow and blood volume weightings. That PBV has preferential (∼60 %) blood flow weighting is an important finding, which is of clinical significance when interpreting the C-arm CT PBV maps, particularly in the setting of acute brain ischemia. (orig.)

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

    International Nuclear Information System (INIS)

    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.)

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

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    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. Shifted detector super short scan reconstruction for the rotate-plus-shift trajectories and its application to C-arm CT systems

    Science.gov (United States)

    Kuntz, Jan; Knaup, Michael; Fleischmann, Christof; Kachelrieß, Marc

    2016-03-01

    Mobile and compact C-arm systems are routinely used in interventional procedures for fluoroscopic CT imaging. The mechanical requirements guarantee for a maximum of flexibility and mobility but restrict the mechanical rotation range (e.g. 165°) and the lateral size of the field of measurement (FOM), typically about 160 mm. Recently, the rotate-plus-shift trajectory for the acquisition of complete datasets from 180° minus fan-angle has been published.1, 2 Here, we combine the rotate-plus-shift trajectory with a shifted detector approach for a fully motorized C-arm system. As the isocenter in non-centric C-arms can be freely chosen, the shifted detector can be equally well absorbed with an offset of the C parallel to the transaxial detector direction. The typical rotation range of 360° used in shifted detector trajectories is replaced by a double rotate-plus-shift scan requiring a rotation range of at least 180° minus fan-angle. The trajectory increasing the diameter of the FOM by up to a factor of two is presented and the practical application of variations with an asymmetric FOM is shown. For image reconstruction we use our modified FDK algorithm that is equipped with a generalized redundancy weight. The presented trajectory can increase the applicability and flexibility of C-arm systems and has the potential to perform intra-operative large volume control or overview scans and thus reduce the patient's risk.

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

    International Nuclear Information System (INIS)

    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.

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

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    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.

  15. Compton detector with flat energy response

    International Nuclear Information System (INIS)

    The work focuses on the study of vacuum Compton detector (VCD) with flat energy response. The proposed VCD adopts a compensation design of' the emitter, i. e. a superimposition of materials of varied thicknesses, and is optimized with Monte Carlo method. The optimally designed VCD consists of an emitter with the superimposition of 0.01, 1 mm-thick Au, a 3 mm-thick Fe front window and a 3 mm-thick Pb shielding. Its non-flatness of energy response to gamma-ray is less than 10.7% over 0.4-7.0 MeV energy zone. The flatness of energy response to gamma ray of this VCD is more excellent than current gamma detectors'. (authors)

  16. Basics principles of flat detector computed tomography (FD-CT)

    International Nuclear Information System (INIS)

    Flat detectors (FDs) have been developed for use in radiography and fluoroscopy to replace standard X-ray film, film-screen combinations and image intensifiers (II). In comparison to X-ray film and II, FD technology offers higher dynamic range, dose reduction, fast digital readout and the possibility for dynamic acquisitions of image series, yet keeping to a compact design. It appeared logical to employ FD designs also for computed tomography (CT) imaging. FDCT has meanwhile become widely accepted for interventional and intra-operative imaging using C-arm systems. Additionally, the introduction of FD technology was a milestone for soft-tissue CT imaging in the interventional suite which was not possible with II systems in the past. This review focuses on technical and performance issues of FD technology and its wide range of applications for CT imaging. FDCT is not aimed at challenging standard clinical CT as regards to the typical diagnostic examinations, but it has already proven unique for a number of dedicated CT applications offering distinct practical advantages, above all the availability of immediate CT imaging during an intervention. (orig.)

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

    International Nuclear Information System (INIS)

    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

  18. Visualization of gastric varices using angiographic C-arm CT during retrograde transvenous sclerotherapy

    International Nuclear Information System (INIS)

    During retrograde transvenous sclerotherapy for gastric varices, sufficient opacification of the target varices on venography is essential for successful treatment. However, venography sometimes cannot identify target varices due to overlapping adjacent collateral vessels or leakage of contrast medium to other outflow veins. We report how C-arm CT images acquired using a flat-panel detector angiography system helped to identify target varices and predict the distribution of a sclerosant, which resulted in safer sclerotherapy and increased operator confidence

  19. Flat-panel detectors in x-ray diagnosis

    International Nuclear Information System (INIS)

    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.)

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

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    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.)

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

    International Nuclear Information System (INIS)

    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.)

  2. Flat-detector CT-based electromagnetic navigation

    International Nuclear Information System (INIS)

    Flat-detector CT coupled to an angiography device provides an imaging technique for interventions which can be used for electromagnetically navigated percutaneous punctures. This report explains the functionality of an electromagnetic navigation system and describes the course of an electromagnetically navigated puncture and the capabilities of such a system in the clinical routine. (orig.)

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

    International Nuclear Information System (INIS)

    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

  4. Flat-response x-ray-diode-detector development

    International Nuclear Information System (INIS)

    In this report we discuss the design of an improved sub-nanosecond flat response x-ray diode detector needed for ICF diagnostics. This device consists of a high Z cathode and a complex filter tailored to flatten the response so that the total x-ray energy below 1.5 keV can be measured using a single detector. Three major problems have become evident as a result of our work with the original LLNL design including deviation from flatness due to a peak in the response below 200 eV, saturation at relatively low x-ray fluences, and long term gold cathode instability. We are investigating grazing incidence reflection to reduce the response below 200 eV, new high Z cathode materials for long term stability, and a new complex filter for improved flatness. Better saturation performance will require a modified XRD detector under development with reduced anode to cathode spacing and increased anode bias voltage

  5. Limited angle C-arm tomosynthesis reconstruction algorithms

    Science.gov (United States)

    Malalla, Nuhad A. Y.; Xu, Shiyu; Chen, Ying

    2015-03-01

    In this paper, C-arm tomosynthesis with digital detector was investigated as a novel three dimensional (3D) imaging technique. Digital tomosythses is an imaging technique to provide 3D information of the object by reconstructing slices passing through the object, based on a series of angular projection views with respect to the object. C-arm tomosynthesis provides two dimensional (2D) X-ray projection images with rotation (-/+20 angular range) of both X-ray source and detector. In this paper, four representative reconstruction algorithms including point by point back projection (BP), filtered back projection (FBP), simultaneous algebraic reconstruction technique (SART) and maximum likelihood expectation maximization (MLEM) were investigated. Dataset of 25 projection views of 3D spherical object that located at center of C-arm imaging space was simulated from 25 angular locations over a total view angle of 40 degrees. With reconstructed images, 3D mesh plot and 2D line profile of normalized pixel intensities on focus reconstruction plane crossing the center of the object were studied with each reconstruction algorithm. Results demonstrated the capability to generate 3D information from limited angle C-arm tomosynthesis. Since C-arm tomosynthesis is relatively compact, portable and can avoid moving patients, it has been investigated for different clinical applications ranging from tumor surgery to interventional radiology. It is very important to evaluate C-arm tomosynthesis for valuable applications.

  6. Dose assessment during the commissioning of flat detector imaging systems for cardiology

    International Nuclear Information System (INIS)

    Incident air kerma (IAK) and entrance surface air kerma (ESAK) have been measured for a range of copper (Cu) absorbers (1-10 mm) and polymethylmethacrylate (PMMA) slabs (12-28 cm) with kilovolt values ranging from 61 to 120 during the commissioning of an X-ray system equipped with a flat detector used in interventional cardiology procedures. Numerical parameters on image quality have also been measured for different X-ray beam qualities using the plastic wall of the ionisation chamber. When moving from 1 to 10 mm of Cu, IAK per frame increased to a factor of 38 for cine and 27 for fluoroscopy. A cine frame requires 60-116 times more IAK than a fluoroscopy frame. As for PMMA, when the backscatter factor is included (simulating real conditions with patients), and when moving from 12 to 28 cm, the increases in ESAK are 16 times for cine and 10 times for fluoroscopy. Because of the differences in X-ray beam quality for cine and fluoroscopy modes, the Cu thicknesses necessary to drive the generator to equivalent kilovolts resulted in the following values (cine and fluoroscopy, respectively): 12 cm of PMMA (1 and 1.5 mm Cu), 20 PMMA (2.5 and 3.5 mm Cu) and 28 cm PMMA (4.5 and 8.5 mm Cu). With the analysis of IAK, ESAK and image quality, one can verify the appropriate settings of the X-ray system and obtain baseline information for constancy checks and help cardiologists in the management of patient doses by knowing the dose increase factors and image quality changes when increasing patient thickness or using different C-arm projections. (authors)

  7. First pass cable artefact correction for cardiac C-arm CT imaging

    International Nuclear Information System (INIS)

    Cardiac C-arm CT imaging delivers a tomographic region-of-interest reconstruction of the patient's heart during image guided catheter interventions. Due to the limited size of the flat detector a volume image is reconstructed, which is truncated in the cone-beam (along the patient axis) and the fan-beam (in the transaxial plane) direction. To practically address this local tomography problem correction methods, like projection extension, are available for first pass image reconstruction. For second pass correction methods, like metal artefact reduction, alternative correction schemes are required when the field of view is limited to a region-of-interest of the patient. In classical CT imaging metal artefacts are corrected by metal identification in a first volume reconstruction and generation of a corrected projection data set followed by a second reconstruction. This approach fails when the metal structures are located outside the reconstruction field of view. When a C-arm CT is performed during a cardiac intervention pacing leads and other cables are frequently positioned on the patients skin, which results in propagating streak artefacts in the reconstruction volume. A first pass approach to reduce this type of artefact is introduced and evaluated here. It makes use of the fact that the projected position of objects outside the reconstruction volume changes with the projection perspective. It is shown that projection based identification, tracking and removal of high contrast structures like cables, only detected in a subset of the projections, delivers a more consistent reconstruction volume with reduced artefact level. The method is quantitatively evaluated based on 50 simulations using cardiac CT data sets with variable cable positioning. These data sets are forward projected using a C-arm CT system geometry and generate artefacts comparable to those observed in clinical cardiac C-arm CT acquisitions. A C-arm CT simulation of every cardiac CT data set

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  10. C-arm computed tomography for transarterial chemoperfusion and chemo-embolization of thoracic lesions; Transarterielle Chemoperfusion und -embolisation thorakaler Neoplasmen mittels C-Arm CT

    Energy Technology Data Exchange (ETDEWEB)

    Vogl, T.J.; Naguib, N.N.; Nour-Eldin, N.E.; Lehnert, T.; Mbalisike, E. [Klinikum der Johann-Wolfgang-Goethe-Universitaet, Institut fuer Diagnostische und Interventionelle Radiologie, Frankfurt am Main (Germany)

    2009-09-15

    To evaluate the role of C-arm CT for on-line fluoroscopy in regional transarterial chemoperfusion (TACP) and chemo-embolization (TPCE) of primary and secondary malignant thoracic lesions. From September 2008 to March 2009 a total of 31 patients (20 males and 11 females, average age: 61.7 years, range 22-84 years) with 53 thoracic malignant lesions from different origins (primary or secondary pulmonary carcinoma n=37, pleural mesothelioma n=16) were treated with TACP or TPCE using flat-detector CT (FD-CT). C-arm CT of the latest generation was used to localize the lesion before local chemotherapy (Artis Zeego, Siemens, Erlangen). For TACP a 220 rotation and a volume of 150 ml (ratio of 1:2 contrast/normal saline), delay 2 s and flow 12 ml/s was used. For TPCE a volume of 75 ml (ratio of 1:2 contrast/normal saline), delay 2 s and flow 3 ml/s was used. TPCE C-arm CT allowed the evaluation of the degree of perfusion of the tumor and the geographic areas of enhancement correlated with the post-interventional lipiodol uptake in MSCT. In TACP the intercostal arteries involved could be visualized and in 30% of interventions the catheter had to be repositioned for the following intervention. C-arm CT provides additional information on the vascular characteristics and perfusion of pulmonary lesions resulting in a change of interventional strategy in a relevant number of patients. (orig.) [German] Ziel der Arbeit war die Evaluation der Wertigkeit der C-Arm CT fuer die online gesteuerte regionale transarterielle Chemoperfusion (TACP) und die transpulmonale Chemoembolisation (TPCE) primaerer und sekundaerer thorakaler Neoplasmen Von September 2008 bis Maerz 2009 wurden 31 Patienten (11 Frauen/20 Maenner, Durchschnittsalter 61,7 Jahre) mit 53 unterschiedlichen thorakalen Neoplasmen (primaere oder sekundaere Lungenkarzinome [n=37], Pleuramesotheliome [n=16]) mittels TACP oder TPCE unter Einsatz der Flachdetektortechnologie (FD-CT) behandelt. Alle Behandlungen erfolgten an einem C

  11. Evaluation of a prototype correction algorithm to reduce metal artefacts in flat detector computed tomography of scaphoid fixation screws

    Energy Technology Data Exchange (ETDEWEB)

    Filli, Lukas; Finkenstaedt, Tim; Andreisek, Gustav; Guggenberger, Roman [University Hospital of Zurich, Department of Diagnostic and Interventional Radiology, Zurich (Switzerland); Marcon, Magda [University Hospital of Zurich, Department of Diagnostic and Interventional Radiology, Zurich (Switzerland); University of Udine, Institute of Diagnostic Radiology, Department of Medical and Biological Sciences, Udine (Italy); Scholz, Bernhard [Imaging and Therapy Division, Siemens AG, Healthcare Sector, Forchheim (Germany); Calcagni, Maurizio [University Hospital of Zurich, Division of Plastic Surgery and Hand Surgery, Zurich (Switzerland)

    2014-12-15

    The aim of this study was to evaluate a prototype correction algorithm to reduce metal artefacts in flat detector computed tomography (FDCT) of scaphoid fixation screws. FDCT has gained interest in imaging small anatomic structures of the appendicular skeleton. Angiographic C-arm systems with flat detectors allow fluoroscopy and FDCT imaging in a one-stop procedure emphasizing their role as an ideal intraoperative imaging tool. However, FDCT imaging can be significantly impaired by artefacts induced by fixation screws. Following ethical board approval, commercially available scaphoid fixation screws were inserted into six cadaveric specimens in order to fix artificially induced scaphoid fractures. FDCT images corrected with the algorithm were compared to uncorrected images both quantitatively and qualitatively by two independent radiologists in terms of artefacts, screw contour, fracture line visibility, bone visibility, and soft tissue definition. Normal distribution of variables was evaluated using the Kolmogorov-Smirnov test. In case of normal distribution, quantitative variables were compared using paired Student's t tests. The Wilcoxon signed-rank test was used for quantitative variables without normal distribution and all qualitative variables. A p value of < 0.05 was considered to indicate statistically significant differences. Metal artefacts were significantly reduced by the correction algorithm (p < 0.001), and the fracture line was more clearly defined (p < 0.01). The inter-observer reliability was ''almost perfect'' (intra-class correlation coefficient 0.85, p < 0.001). The prototype correction algorithm in FDCT for metal artefacts induced by scaphoid fixation screws may facilitate intra- and postoperative follow-up imaging. (orig.)

  12. Evaluation of a prototype correction algorithm to reduce metal artefacts in flat detector computed tomography of scaphoid fixation screws

    International Nuclear Information System (INIS)

    The aim of this study was to evaluate a prototype correction algorithm to reduce metal artefacts in flat detector computed tomography (FDCT) of scaphoid fixation screws. FDCT has gained interest in imaging small anatomic structures of the appendicular skeleton. Angiographic C-arm systems with flat detectors allow fluoroscopy and FDCT imaging in a one-stop procedure emphasizing their role as an ideal intraoperative imaging tool. However, FDCT imaging can be significantly impaired by artefacts induced by fixation screws. Following ethical board approval, commercially available scaphoid fixation screws were inserted into six cadaveric specimens in order to fix artificially induced scaphoid fractures. FDCT images corrected with the algorithm were compared to uncorrected images both quantitatively and qualitatively by two independent radiologists in terms of artefacts, screw contour, fracture line visibility, bone visibility, and soft tissue definition. Normal distribution of variables was evaluated using the Kolmogorov-Smirnov test. In case of normal distribution, quantitative variables were compared using paired Student's t tests. The Wilcoxon signed-rank test was used for quantitative variables without normal distribution and all qualitative variables. A p value of < 0.05 was considered to indicate statistically significant differences. Metal artefacts were significantly reduced by the correction algorithm (p < 0.001), and the fracture line was more clearly defined (p < 0.01). The inter-observer reliability was ''almost perfect'' (intra-class correlation coefficient 0.85, p < 0.001). The prototype correction algorithm in FDCT for metal artefacts induced by scaphoid fixation screws may facilitate intra- and postoperative follow-up imaging. (orig.)

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

    International Nuclear Information System (INIS)

    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.)

  14. Efficiency of antiscatter grids for flat-detector CT

    Energy Technology Data Exchange (ETDEWEB)

    Kyriakou, Yiannis; Kalender, Willi [Institute of Medical Physics, University of Erlangen-Nuernberg, Henkestrasse 91, 91052 Erlangen (Germany)

    2007-10-21

    Flat-panel detector CT (FD-CT) scanners offer large volume coverage, but as a consequence are more susceptible to scatter artifacts than standard clinical CT scanners with smaller cone angles. FD-CT scanners can employ antiscatter grids as a scatter rejection technique. We evaluated three standard fluoroscopic antiscatter grids for two different field sizes with respect to scatter suppression efficiency and image quality improvement. The evaluations included simulations and measurements. Regarding the simulation a hybrid model combining deterministic and Monte Carlo (MC) calculations was used combined with an analytical calculation of grid transmission. The scatter-to-primary ratio (SPR) was measured using an adapted collimator technique in order to validate our simulations. The SPR obtained by simulations and measurements with and without antiscatter grids were in agreement typically within 10%. The employment of a grid does not generally provide a significant improvement of the signal-to-noise ratio (SNR). Antiscatter grids led to a significant reduction of cupping artifacts in all cases. There is a trade-off between the SNR and the reduction of the scatter intensity described by the signal-to-noise improvement factor (SNR{sub if}). For low- or medium-scatter conditions the increase in noise caused by the reduced primary transmission through the grid has to be compensated by a higher exposure. For high scatter conditions SNR{sub if} is significantly greater than 1; i.e. a decrease of dose of up to 50% can be reached.

  15. Flat-detector computed tomography in diagnostic and interventional neuroradiology; Flachdetektor-CT in der diagnostischen und interventionellen Neuroradiologie

    Energy Technology Data Exchange (ETDEWEB)

    Struffert, T.; Doerfler, A. [Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Abteilung fuer Neuroradiologie, Universitaetsklinikum Erlangen, Erlangen (Germany)

    2009-09-15

    Originally aimed at improving standard radiography by providing higher absorption efficiency and a wider dynamic range than available with film-screen and phosphor luminescence, radiography flat detector technology is now widely accepted for neuroangiographic imaging. Especially flat-detector computed tomography (FD-CT), which uses rotational C-arm mounted flat-panel detector technology, is capable of volumetric imaging with a high spatial resolution. As ''angiographic CT'' FD-CT may be helpful in many diagnostic and neurointerventional procedures, e.g. intracranial stenting for cerebrovascular stenoses, stent-assisted coil embolization of wide-necked cerebral aneurysms and embolization of arteriovenous malformations. By providing morphologic, CT-like images of the brain within the angiography suite FD-CT allows rapid visualization of periprocedural hemorrhaging and may thus improve rapid complication management without the need of patient transfer. In addition, myelography and postmyelographic FD-CT imaging can be carried out using a single modality. Spinal interventions, such as kyphoplasty or vertebroplasty might also benefit from FD-CT. Imaging of the temporal bone may also develop into an important field of FD-CT. This paper briefly reviews the technical principles of FD technology and the potential applications in diagnostic and interventional neuroradiology. (orig.) [German] Flachbilddetektoren wurden urspruenglich entwickelt, um bei projektionsradiographischen Anwendungen die Absorptionseffizienz zu verbessern und den Dynamikbereich zu erhoehen. Zunehmend finden diese FD-Systeme nun auch in der Neuroangiographie Anwendung. Insbesondere als C-Bogen-gestuetzte Rotationsangiographie erlauben Flachdetektorsysteme eine schnelle Akquisition von Volumendaten mit der Moeglichkeit der sekundaeren Rekonstruktion CT-aehnlicher Schnittbilder in hoher Ortsaufloesung. Die Akquisition von Datensaetzen mit guter Weichteilkontrastaufloesung unmittelbar

  16. Flat detector computed tomography in diagnostic and interventional pediatric cardiology

    International Nuclear Information System (INIS)

    Purpose: In this study the use of flat detector computed tomography (FD-CT) in the catheterization of patients with congenital heart disease was evaluated. Application reports were created for various issues based on the achieved image quality in diverse anatomical regions. Materials and Methods: FD-CT was applied in 176 cases during catheterization between January 2010 and April 2012. A five-point Likert scale ('essential' to 'misleading') was used to evaluate image quality. All cases were analyzed retrospectively and application reports for the visualization of the aorta, pulmonary arteries, pulmonary veins, semilunar valves, cavopulmonary connections and atrial baffles were generated. Contrast dye consumption and radiation dose were evaluated. Results: During the observation period FD-CT was applied in all 176 cases. The mean patient age was 7.0 years (0.01 - 42.53 years). The clinical value of FD-CT was rated superior to conventional angiography in 96.6 % of the cases and was never rated as 'misleading'. FD-CT was rated 'essential' in 3.4 % of all cases, 'very useful' in 77.3 % of all cases, 'useful' in 15.9 % of all cases and 'not useful' in 3.4 % of all cases. The mean dose-area product was 99 μGym2 (19.3 - 1276.6 μGym2), and the used contrast dye was 1.76 ml/kg (0.9 - 5 ml/kg). Application reports for the visualization of different anatomical regions are demonstrated. Conclusion: FD-CT is a new and auxiliary procedure in diagnostic and interventional catheterization of patients with congenital heart disease. Particularly extracardiac structures can be displayed in three-dimensional high resolution and be used for diagnosis, surgical planning and 3 D navigation. (orig.)

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

    International Nuclear Information System (INIS)

    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)

  18. Intraoperative imaging for patient safety and QA: detection of intracranial hemorrhage using C-arm cone-beam CT

    Science.gov (United States)

    Schafer, Sebastian; Wang, Adam; Otake, Yoshito; Stayman, J. W.; Zbijewski, Wojciech; Kleinszig, Gerhard; Xia, Xuewei; Gallia, Gary L.; Siewerdsen, Jeffrey H.

    2013-03-01

    Intraoperative imaging could improve patient safety and quality assurance (QA) via the detection of subtle complications that might otherwise only be found hours after surgery. Such capability could therefore reduce morbidity and the need for additional intervention. Among the severe adverse events that could be more quickly detected by high-quality intraoperative imaging is acute intracranial hemorrhage (ICH), conventionally assessed using post-operative CT. A mobile C-arm capable of high-quality cone-beam CT (CBCT) in combination with advanced image reconstruction techniques is reported as a means of detecting ICH in the operating room. The system employs an isocentric C-arm with a flat-panel detector in dual gain mode, correction of x-ray scatter and beam-hardening, and a penalized likelihood (PL) iterative reconstruction method. Performance in ICH detection was investigated using a quantitative phantom focusing on (non-contrast-enhanced) blood-brain contrast, an anthropomorphic head phantom, and a porcine model with injection of fresh blood bolus. The visibility of ICH was characterized in terms of contrast-to-noise ratio (CNR) and qualitative evaluation of images by a neurosurgeon. Across a range of size and contrast of the ICH as well as radiation dose from the CBCT scan, the CNR was found to increase from ~2.2-3.7 for conventional filtered backprojection (FBP) to ~3.9-5.4 for PL at equivalent spatial resolution. The porcine model demonstrated superior ICH detectability for PL. The results support the role of high-quality mobile C-arm CBCT employing advanced reconstruction algorithms for detecting subtle complications in the operating room at lower radiation dose and lower cost than intraoperative CT scanners and/or fixedroom C-arms. Such capability could present a potentially valuable aid to patient safety and QA.

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

    International Nuclear Information System (INIS)

    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)

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

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    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.

  2. Response of the Unruh-DeWitt detector in flat spacetime with a compact dimension

    CERN Document Server

    Chiou, Dah-Wei

    2016-01-01

    In a flat spacetime with one spatial dimension compactified, inertial reference frames are not all equivalent, but there are the preferred ones. This paper investigates nonequivalence of inertial frames in connection with responses of the Unruh-DeWitt detector coupled to a massless scalar field. If the detector moves with an arbitrary constant velocity, it registers no signals. However, within an inertial frame, by instantaneously accelerating the Unruh-DeWitt detector, one can infer the length of the compact dimension and the frame's moving velocity in the compact direction with respect to the preferred frame from the detector's response to acceleration.

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

    OpenAIRE

    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...

  4. Clinical applications: Mobile C-arm systems

    International Nuclear Information System (INIS)

    The introduction of the image intensifier opened up new perspectives in surgery and interventional radiology. This article traces the development of mobile C-arm systems from the first surgical systems to modern systems such as the BV Pulsera with 3D rotational imaging. (orig.)

  5. Accuracy of x-ray image-based 3D localization from two C-arm views: a comparison between an ideal system and a real device

    Science.gov (United States)

    Brost, Alexander; Strobel, Norbert; Yatziv, Liron; Gilson, Wesley; Meyer, Bernhard; Hornegger, Joachim; Lewin, Jonathan; Wacker, Frank

    2009-02-01

    arm X-ray imaging devices are commonly used for minimally invasive cardiovascular or other interventional procedures. Calibrated state-of-the-art systems can, however, not only be used for 2D imaging but also for three-dimensional reconstruction either using tomographic techniques or even stereotactic approaches. To evaluate the accuracy of X-ray object localization from two views, a simulation study assuming an ideal imaging geometry was carried out first. This was backed up with a phantom experiment involving a real C-arm angiography system. Both studies were based on a phantom comprising five point objects. These point objects were projected onto a flat-panel detector under different C-arm view positions. The resulting 2D positions were perturbed by adding Gaussian noise to simulate 2D point localization errors. In the next step, 3D point positions were triangulated from two views. A 3D error was computed by taking differences between the reconstructed 3D positions using the perturbed 2D positions and the initial 3D positions of the five points. This experiment was repeated for various C-arm angulations involving angular differences ranging from 15° to 165°. The smallest 3D reconstruction error was achieved, as expected, by views that were 90° degrees apart. In this case, the simulation study yielded a 3D error of 0.82 mm +/- 0.24 mm (mean +/- standard deviation) for 2D noise with a standard deviation of 1.232 mm (4 detector pixels). The experimental result for this view configuration obtained on an AXIOM Artis C-arm (Siemens AG, Healthcare Sector, Forchheim, Germany) system was 0.98 mm +/- 0.29 mm, respectively. These results show that state-of-the-art C-arm systems can localize instruments with millimeter accuracy, and that they can accomplish this almost as well as an idealized theoretical counterpart. High stereotactic localization accuracy, good patient access, and CT-like 3D imaging capabilities render state-of-the-art C-arm systems ideal devices for X

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

    Science.gov (United States)

    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

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

    International Nuclear Information System (INIS)

    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

  8. Compensational scintillation detector with a flat energy response for flash X-ray measurements

    International Nuclear Information System (INIS)

    To measure the intensity of flash X-ray sources directly, a novel scintillation detector with a fast time response and flat energy response is developed by combining film scintillators of doped ZnO crystal and fast organic scintillator together. Through compensation design, the dual-scintillator detector (DSD) achieved a flat energy response to X-rays from tens of keV to several MeV, and sub-nanosecond time response by coupling to ultrafast photo-electronic devices. A prototype detector was fabricated according to the theoretical design; it employed ZnO:In and EJ228 with thicknesses of 0.3 mm and 0.1 mm, respectively. The energy response of this detector was tested on monoenergetic X-ray and γ-ray sources. The detector performs very well with a sensitivity fluctuation below 5% for 8 discrete energy points within the 40–250 keV energy region and for other energies of 662 keV and 1.25 MeV as well, showing good accordance with the theoretical design. Additionally, the detector works properly for the application to the flash X-ray radiation field absolute intensity measurement. This DSD may be very useful for the diagnosis of time-resolved dynamic physical processes of flash X-ray sources without knowing the exact energy spectrum.

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

    International Nuclear Information System (INIS)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Automatic analysis of quality of images from X-ray digital flat detectors

    International Nuclear Information System (INIS)

    Since last decade, medical imaging has grown up with the development of new digital imaging techniques. In the field of X-ray radiography, new detectors replace progressively older techniques, based on film or x-ray intensifiers. These digital detectors offer a higher sensibility and reduced overall dimensions. This work has been prepared with Trixell, the world leading company in flat detectors for medical radiography. It deals with quality control on digital images stemming from these detectors. High quality standards of medical imaging impose a close analysis of the defects that can appear on the images. This work describes a complete process for quality analysis of such images. A particular focus is given on the detection task of the defects, thanks to methods well adapted to our context of spatially correlated defects in noise background. (author)

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

    International Nuclear Information System (INIS)

    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)

  13. Note: Continuing improvements on the novel flat-response x-ray detector

    International Nuclear Information System (INIS)

    This note describes multi-updates of the novel flat-response x-ray detector in fabrication technology, experimental application, and data uncertainty evaluation. Unlike the previous design, the compound filter is combined into one piece through an improved fabrication process that greatly enhanced its self-supporting capability. A method of pinhole-array imaging is introduced into the experimental application process to stop any debris from the hohlraum and to uniformly reduce the radiation flux. The experimental results show that this method works well. Furthermore, a method of uncertainty evaluation of the radiation flux measurement by the novel flat-response x-ray detector has been developed. The influence of the radiation spectrum to the flux measurement is analyzed. The evaluation shows that the relative uncertainty of the radiation flux is about 10% in higher radiation temperature condition (Tr > 150 eV) and 16% in lower radiation temperature condition (Tr < 100 eV).

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

    International Nuclear Information System (INIS)

    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)

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  16. Magnetic navigation versus mobile C-Arm

    International Nuclear Information System (INIS)

    The aim of this study was to demonstrate differences in radiation protection aspects between the use of a digital cardio angiography system with magnetic navigation (Artis Axiom dFcM + Stereotaxis NIOBE (registered) Magnetic Navigation System) and a standard mobile X-ray device with C-arm for electrophysiological procedures. Radiation exposure to staff and patients were analyzed and used for comparison. The time distribution of cardiology procedures for one physician is shown to introduce work of electrophysiology section. The records of procedures were used as information and as a data source for this study. These records include written operation as well as printed exam protocols. This study shows time course of procedures using the electro anatomical mapping system 'CARTO'. A single physicians performance has been used for this comparison to avoid possible differences between operators. The exposure time and air kerma product (PKA) values have been compared for both devices. Median value of exposure time, for each group of 20 patients, was reduced from 27.1 minutes to 20.0 minutes and radiation exposure from 12468 cGycm2 to 9078 cGycm2 PKA values. There is also scattered radiation in the operation area for C-Arm and the new technology presented. Magnetic navigation and replacing C-Arm by cardio angiography system reduces the personal dose by nearly one third, this fact was traced from personal monitoring reports. The main reason for saving time is the necessity to operate the catheter by joystick on a control panel from an adjacent room. These new technologies bring more effectiveness into interventional procedures, especially in cases of complicated examination, and reduce radiation exposure to patients and staff significantly. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.)

  18. Flat-Field Calibration of CCD Detector for Long Trace Profilers

    International Nuclear Information System (INIS)

    The next generation of synchrotrons and free electron lasers requires x-ray optical systems with extremely high-performance, generally, of diffraction limited quality. Fabrication and use of such optics requires highly accurate metrology. In the present paper, we discuss a way to improve the performance of the Long Trace Profiler (LTP), a slope measuring instrument widely used at synchrotron facilities to characterize x-ray optics at high-spatial-wavelengths from approximately 2 mm to 1 m. One of the major sources of LTP systematic error is the detector. For optimal functionality, the detector has to possess the smallest possible pixel size/spacing, a fast method of shuttering, and minimal non-uniformity of pixel-to-pixel photoresponse. While the first two requirements are determined by choice of detector, the non-uniformity of photoresponse of typical detectors such as CCD cameras is around 2-3 percent. We describe a flat-field calibration setup specially developed for calibration of CCD camera photo-response and dark current with an accuracy of better than 0.5 percent. Such accuracy is adequate for use of a camera as a detector for an LTP with performance of ∼0.1 microradian (rms). We also present the design details of the calibration system and results of calibration of a DALSA CCD camera used for upgrading our LTP-II instrument at the ALS Optical Metrology Laboratory

  19. Flat-Field Calibration of CCD Detector for Long TraceProfilers

    Energy Technology Data Exchange (ETDEWEB)

    Kirschman, Jonathan L.; Domning, Edward E.; Franck, Keith D.; Irick, Steve C.; MacDowell, Alastair A.; McKinney, Wayne R.; Morrison,Gregory Y.; Smith, Brian V.; Warwick, Tony; Yashchuk, Valeriy V.

    2007-07-31

    The next generation of synchrotrons and free electron lasersrequires x-ray optical systems with extremely high-performance,generally, of diffraction limited quality. Fabrication and use of suchoptics requires highly accurate metrology. In the present paper, wediscuss a way to improve the performance of the Long Trace Profiler(LTP), a slope measuring instrument widely used at synchrotron facilitiesto characterize x-ray optics at high-spatial-wavelengths fromapproximately 2 mm to 1 m. One of the major sources of LTP systematicerror is the detector. For optimal functionality, the detector has topossess the smallest possible pixel size/spacing, a fast method ofshuttering, and minimal non-uniformity of pixel-to-pixel photoresponse.While the first two requirements are determined by choice of detector,the non-uniformity of photoresponse of typical detectors such as CCDcameras is around 2-3 percent. We describe a flat-field calibration setupspecially developed for calibration of CCD camera photo-response and darkcurrent with an accuracy of better than 0.5 percent. Such accuracy isadequate for use of a camera as a detector for an LTP with performance of~;0.1 microradian (rms). We also present the design details of thecalibration system and results of calibration of a DALSA CCD camera usedfor upgrading our LTP-II instrument at the ALS Optical MetrologyLaboratory.

  20. Dose optimisation for intraoperative cone-beam flat-detector CT in paediatric spinal surgery

    Energy Technology Data Exchange (ETDEWEB)

    Petersen, Asger Greval [Region of Northern Jutland, Department of X-ray Physics, Broenderslev (Denmark); Eiskjaer, Soeren; Kaspersen, Jon [Aalborg University Hospital, The Spinal Unit, Department of Orthopaedic Surgery, Aalborg (Denmark)

    2012-08-15

    During surgery for spinal deformities, accurate placement of pedicle screws may be guided by intraoperative cone-beam flat-detector CT. The purpose of this study was to identify appropriate paediatric imaging protocols aiming to reduce the radiation dose in line with the ALARA principle. Using O-arm registered (Medtronic, Inc.), three paediatric phantoms were employed to measure CTDI{sub w} doses with default and lowered exposure settings. Images from 126 scans were evaluated by two spinal surgeons and scores were compared (Kappa statistics). Effective doses were calculated. The recommended new low-dose 3-D spine protocols were then used in 15 children. The lowest acceptable exposure as judged by image quality for intraoperative use was 70 kVp/40 mAs, 70 kVp/80 mAs and 80 kVp/40 mAs for the 1-, 5- and 12-year-old-equivalent phantoms respectively (kappa = 0,70). Optimised dose settings reduced CTDI{sub w} doses 89-93%. The effective dose was 0.5 mSv (91-94,5% reduction). The optimised protocols were used clinically without problems. Radiation doses for intraoperative 3-D CT using a cone-beam flat-detector scanner could be reduced at least 89% compared to manufacturer settings and still be used to safely navigate pedicle screws. (orig.)

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

    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)

  3. Paediatric interventional cardiology: flat detector versus image intensifier using a test object

    International Nuclear Information System (INIS)

    Entrance surface air kerma (ESAK) values and image quality parameters were measured and compared for two biplane angiography x-ray systems dedicated to paediatric interventional cardiology, one equipped with image intensifiers (II) and the other one with dynamic flat detectors (FDs). Polymethyl methacrylate phantoms of different thicknesses, ranging from 8 to 16 cm, and a Leeds TOR 18-FG test object were used. The parameters of the image quality evaluated were noise, signal-difference-to-noise ratio (SdNR), high contrast spatial resolution (HCSR) and three figures of merit combining entrance doses and signal-to-noise ratios or HCSR. The comparisons showed a better behaviour of the II-based system in the low contrast region over the whole interval of thicknesses. The FD-based system showed a better performance in HCSR. The FD system evaluated would need around two times more dose than the II system evaluated to reach a given value of SdNR; moreover, a better spatial resolution was measured (and perceived in conventional monitors) for the system equipped with flat detectors. According to the results of this paper, the use of dynamic FD systems does not lead to an automatic reduction in ESAK or to an automatic improvement in image quality by comparison with II systems. Any improvement also depends on the setting of the x-ray systems and it should still be possible to refine these settings for some of the dynamic FDs used in paediatric cardiology.

  4. The rotate-plus-shift C-arm trajectory: complete CT data with limited angular rotation

    Science.gov (United States)

    Ritschl, Ludwig; Kuntz, Jan; Kachelrieß, Marc

    2015-03-01

    In the last decade C-arm-based cone-beam CT became a widely used modality for intraoperative imaging. Typically a C-arm scan is performed using a circle-like trajectory around a region of interest. Therefor an angular range of at least 180° plus fan-angle must be covered to ensure a completely sampled data set. This fact defines some constraints on the geometry and technical specifications of a C-arm system, for example a larger C radius or a smaller C opening respectively. These technical modifications are usually not beneficial in terms of handling and usability of the C-arm during classical 2D applications like fluoroscopy. The method proposed in this paper relaxes the constraint of 180° plus fan-angle rotation to acquire a complete data set. The proposed C-arm trajectory requires a motorization of the orbital axis of the C and of ideally two orthogonal axis in the C plane. The trajectory consists of three parts: A rotation of the C around a defined iso-center and two translational movements parallel to the detector plane at the begin and at the end of the rotation. Combining these three parts to one trajectory enables for the acquisition of a completely sampled dataset using only 180° minus fan-angle of rotation. To evaluate the method we show animal and cadaver scans acquired with a mobile C-arm prototype. We expect that the transition of this method into clinical routine will lead to a much broader use of intraoperative 3D imaging in a wide field of clinical applications.

  5. A novel forward projection-based metal artifact reduction method for flat-detector computed tomography

    International Nuclear Information System (INIS)

    Metallic implants generate streak-like artifacts in flat-detector computed tomography (FD-CT) reconstructed volumetric images. This study presents a novel method for reducing these disturbing artifacts by inserting discarded information into the original rawdata using a three-step correction procedure and working directly with each detector element. Computation times are minimized by completely implementing the correction process on graphics processing units (GPUs). First, the original volume is corrected using a three-dimensional interpolation scheme in the rawdata domain, followed by a second reconstruction. This metal artifact-reduced volume is then segmented into three materials, i.e. air, soft-tissue and bone, using a threshold-based algorithm. Subsequently, a forward projection of the obtained tissue-class model substitutes the missing or corrupted attenuation values directly for each flat detector element that contains attenuation values corresponding to metal parts, followed by a final reconstruction. Experiments using tissue-equivalent phantoms showed a significant reduction of metal artifacts (deviations of CT values after correction compared to measurements without metallic inserts reduced typically to below 20 HU, differences in image noise to below 5 HU) caused by the implants and no significant resolution losses even in areas close to the inserts. To cover a variety of different cases, cadaver measurements and clinical images in the knee, head and spine region were used to investigate the effectiveness and applicability of our method. A comparison to a three-dimensional interpolation correction showed that the new approach outperformed interpolation schemes. Correction times are minimized, and initial and corrected images are made available at almost the same time (12.7 s for the initial reconstruction, 46.2 s for the final corrected image compared to 114.1 s and 355.1 s on central processing units (CPUs)).

  6. Changing from image intensifier to flat detector technology for interventional cardiology procedures: A practical point of view

    International Nuclear Information System (INIS)

    A small-scale internal audit has been used to evaluate the impact of the use of a dynamic flat panel detector in the clinical routine in the National Interventional Cardiology Centre in Luxembourg. The parameters tested during commissioning and constancy control of an X-ray system, the introduction of new clinical protocols, the patient and the personal staff dosimetry were considered. The technical parameters tested by the hospital physicist stay the same as for the image intensifier. No innovative protocols have been adopted due to the existence of the flat panel detector. A reduction in dose was noted after the installation of a flat detector, due mostly to the continuing education of the interventional cardiologists as well as the initial calibration of the radiological system. The understanding of the X-ray system and its possibilities is vital for the optimisation of clinical procedures in patient and staff exposure. (authors)

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

    International Nuclear Information System (INIS)

    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)

  8. Changing from image intensifier to flat detector technology for interventional cardiology procedures: a practical point of view.

    Science.gov (United States)

    Bokou, C; Schreiner-Karoussou, A; Breisch, R; Beissel, J

    2008-01-01

    A small-scale internal audit has been used to evaluate the impact of the use of a dynamic flat panel detector in the clinical routine in the National Interventional Cardiology Centre in Luxembourg. The parameters tested during commissioning and constancy control of an X-ray system, the introduction of new clinical protocols, the patient and the personal staff dosimetry were considered. The technical parameters tested by the hospital physicist stay the same as for the image intensifier. No innovative protocols have been adopted due to the existence of the flat panel detector. A reduction in dose was noted after the installation of a flat detector, due mostly to the continuing education of the interventional cardiologists as well as the initial calibration of the radiological system. The understanding of the X-ray system and its possibilities is vital for the optimisation of clinical procedures in patient and staff exposure. PMID:18448437

  9. Antiscatter grids in mobile C-arm cone-beam CT: Effect on image quality and dose

    International Nuclear Information System (INIS)

    Purpose: X-ray scatter is a major detriment to image quality in cone-beam CT (CBCT). Existing geometries exhibit strong differences in scatter susceptibility with more compact geometries, e.g., dental or musculoskeletal, benefiting from antiscatter grids, whereas in more extended geometries, e.g., IGRT, grid use carries tradeoffs in image quality per unit dose. This work assesses the tradeoffs in dose and image quality for grids applied in the context of low-dose CBCT on a mobile C-arm for image-guided surgery. Methods: Studies were performed on a mobile C-arm equipped with a flat-panel detector for high-quality CBCT. Antiscatter grids of grid ratio (GR) 6:1-12:1, 40 lp/cm, were tested in ''body'' surgery, i.e., spine, using protocols for bone and soft-tissue visibility in the thoracic and abdominal spine. Studies focused on grid orientation, CT number accuracy, image noise, and contrast-to-noise ratio (CNR) in quantitative phantoms at constant dose. Results: There was no effect of grid orientation on possible gridline artifacts, given accurate angle-dependent gain calibration. Incorrect calibration was found to result in gridline shadows in the projection data that imparted high-frequency artifacts in 3D reconstructions. Increasing GR reduced errors in CT number from 31%, thorax, and 37%, abdomen, for gridless operation to 2% and 10%, respectively, with a 12:1 grid, while image noise increased by up to 70%. The CNR of high-contrast objects was largely unaffected by grids, but low-contrast soft-tissues suffered reduction in CNR, 2%-65%, across the investigated GR at constant dose. Conclusions: While grids improved CT number accuracy, soft-tissue CNR was reduced due to attenuation of primary radiation. CNR could be restored by increasing dose by factors of ∼1.6-2.5 depending on GR, e.g., increase from 4.6 mGy for the thorax and 12.5 mGy for the abdomen without antiscatter grids to approximately 12 mGy and 30 mGy, respectively, with a high-GR grid. However

  10. Criteria to optimise a dynamic flat detector system used for interventional radiology

    International Nuclear Information System (INIS)

    An analysis of the relationship between image quality and incident air kerma has been carried out for a dynamic flat detector X-ray system used for interventional radiology. A phantom of polymethyl methacrylate (PMMA) to simulate patients and two different image test objects, Leeds TOR 18FG and NEMA XR 21, were used to evaluate the quality of the obtained images. Measurements were made simulating clinical configuration with different PMMA thicknesses (16, 20, 24 and 28 cm), available fields of view of 22, 31, 42 and 48 cm (diagonal dimension), in the three default fluoroscopy modes and in one of the most used digital subtraction angiography image acquisition modes. The obtained results are being used to help in the optimisation of clinical procedures. (authors)

  11. Heel effect adaptive flat field correction of digital x-ray detectors

    International Nuclear Information System (INIS)

    Purpose: Anode heel effect renders large-scale background nonuniformities in digital radiographs. Conventional offset/gain calibration is performed at mono source-to-image distance (SID), and disregards the SID-dependent characteristic of heel effect. It results in a residual nonuniform background in the corrected radiographs when the SID settings for calibration and correction differ. In this work, the authors develop a robust and efficient computational method for digital x-ray detector gain correction adapted to SID-variant heel effect, without resorting to physical filters, phantoms, complicated heel effect models, or multiple-SID calibration and interpolation.Methods: The authors present the Duo-SID projection correction method. In our approach, conventional offset/gain calibrations are performed only twice, at the minimum and maximum SIDs of the system in typical clinical use. A fast iterative separation algorithm is devised to extract the detector gain and basis heel patterns from the min/max SID calibrations. The resultant detector gain is independent of SID, while the basis heel patterns are parameterized by the min- and max-SID. The heel pattern at any SID is obtained from the min-SID basis heel pattern via projection imaging principles. The system gain desired at a specific acquisition SID is then constructed using the projected heel pattern and detector gain map.Results: The method was evaluated for flat field and anatomical phantom image corrections. It demonstrated promising improvements over interpolation and conventional gain calibration/correction methods, lowering their correction errors by approximately 70% and 80%, respectively. The separation algorithm was able to extract the detector gain and heel patterns with less than 2% error, and the Duo-SID corrected images showed perceptually appealing uniform background across the detector.Conclusions: The Duo-SID correction method has substantially improved on conventional offset/gain corrections for

  12. Heel effect adaptive flat field correction of digital x-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Yongjian [X-ray Products, Varian Medical Systems Inc., Liverpool, New York 13088 (United States); Wang, Jue [Department of Mathematics, Union College, Schenectady, New York 12308 (United States)

    2013-08-15

    Purpose: Anode heel effect renders large-scale background nonuniformities in digital radiographs. Conventional offset/gain calibration is performed at mono source-to-image distance (SID), and disregards the SID-dependent characteristic of heel effect. It results in a residual nonuniform background in the corrected radiographs when the SID settings for calibration and correction differ. In this work, the authors develop a robust and efficient computational method for digital x-ray detector gain correction adapted to SID-variant heel effect, without resorting to physical filters, phantoms, complicated heel effect models, or multiple-SID calibration and interpolation.Methods: The authors present the Duo-SID projection correction method. In our approach, conventional offset/gain calibrations are performed only twice, at the minimum and maximum SIDs of the system in typical clinical use. A fast iterative separation algorithm is devised to extract the detector gain and basis heel patterns from the min/max SID calibrations. The resultant detector gain is independent of SID, while the basis heel patterns are parameterized by the min- and max-SID. The heel pattern at any SID is obtained from the min-SID basis heel pattern via projection imaging principles. The system gain desired at a specific acquisition SID is then constructed using the projected heel pattern and detector gain map.Results: The method was evaluated for flat field and anatomical phantom image corrections. It demonstrated promising improvements over interpolation and conventional gain calibration/correction methods, lowering their correction errors by approximately 70% and 80%, respectively. The separation algorithm was able to extract the detector gain and heel patterns with less than 2% error, and the Duo-SID corrected images showed perceptually appealing uniform background across the detector.Conclusions: The Duo-SID correction method has substantially improved on conventional offset/gain corrections for

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

    International Nuclear Information System (INIS)

    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.

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

    Science.gov (United States)

    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

  15. Application of C-arm computed tomography in cardiology; Kardiale Anwendung der C-Arm-Computertomographie

    Energy Technology Data Exchange (ETDEWEB)

    Rieber, J. [Klinikum der Ludwig-Maximilians-Universitaet Muenchen, Campus Innenstadt, Abteilung fuer Kardiologie, Medizinische Poliklinik, Muenchen (Germany); Rohkohl, C. [Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Lehrstuhl fuer Mustererkennung, Department Informatik, Erlangen (Germany); Siemens AG, Healthcare Sector, Forchheim, Forchheim (Germany); Lauritsch, G. [Siemens AG, Healthcare Sector, Forchheim, Forchheim (Germany); Rittger, H. [Krankenhaus Coburg, Abteilung fuer Kardiologie, Coburg (Germany); Meissner, O. [Siemens AG, Healthcare Sector, Forchheim, Forchheim (Germany); Klinikum der Ludwig-Maximilians-Universitaet Muenchen, Institut fuer Klinische Radiologie, Muenchen (Germany)

    2009-09-15

    C-arm computed tomography is currently being introduced into cardiac imaging and offers the potential for three-dimensional imaging of the cardiac anatomy within the interventional environment. This detailed view is necessary to support complex interventional strategies, such as transcutaneous valve replacement, interventional therapy of atrial fibrillation, implantation of biventricular pacemakers and assessment of myocardial perfusion. Currently, the major limitation of this technology is its insufficient temporal resolution which limits the visualization of fast moving parts of the heart. (orig.) [German] Durch die Entwicklung der C-Arm-Computertomographie- (CACT-)Angiographie ist es erstmals moeglich, waehrend einer Herzkatheteruntersuchung eine detaillierte dreidimensionale Darstellung der kardialen Anatomie zu erhalten. Derartige zusaetzliche Informationen koennten die Durchfuehrung der immer komplexer werdenden Strategien der interventionellen Kardiologie wirkungsvoll unterstuetzen. Hierzu zaehlen u. a. der transkutane Klappenersatz, die interventionelle Behandlung von Vorhofflimmern, die Implantation biventrikulaerer Schrittmacher sowie die Beurteilung der Myokardperfusion. Die derzeit groesste Limitation dieser Methode ist die relativ geringe zeitliche Aufloesung, die aufgrund der Bewegung des Herzens die Anwendung dieser Technologie einschraenkt. (orig.)

  16. Cone-beam CT using a mobile C-arm: a registration solution for IGRT with an optical tracking system

    International Nuclear Information System (INIS)

    A method for registering images acquired from a prototype flat panel mobile C-arm, capable of kilovoltage (kV) cone-beam computed tomography (CT), to a linear accelerator (LINAC) isocenter is presented. A calibration procedure is performed which involves locating reflective markers placed on the C-arm and a phantom in two coordinate systems. A commercial optical tracking system locates the markers relative to the LINAC isocenter (room coordinates). The cone-beam imaging capabilities of the C-arm provide the location of the markers on the calibration phantom in image coordinates. A singular value decomposition (SVD) algorithm is used to determine the relationship between the C-arm, image coordinates and room coordinates. Once the calibration is completed, the position of the C-arm at any arbitrary location is accurately determined from the tracking system. A final transformation is calculated capable of mapping voxels in the reconstructed image set to their corresponding position in room coordinates. An evaluation to determine the accuracy of this method was performed by locating markers on a phantom. The position of the phantom markers in room coordinates was obtained directly using the optical tracking system and compared with that using the described method above. A mean absolute distance of 1.4 ± 0.5 was observed for a completely transformed image set. This is comparable to that of systems routinely used for image-guided radiation therapy (IGRT)

  17. The clinical application of C arm CT imaging in diagnosing and treating hypo-vascular primary hepatic carcinomas

    International Nuclear Information System (INIS)

    Objective: To investigate the clinical application of C arm CT imaging technique in diagnosing and treating of hypo-vascular primary hepatic carcinomas. Methods: Forty-three patients with hypo-vascular primary hepatic carcinomas were enrolled in this study. All the patients underwent DSA and C arm CT imaging (Philips dual x-ray flat-panel digital imaging system) before transcatheter arterial chemoembolization (TACE). The imaging findings were retrospectively analyzed. The detection rate of hepatic tumors estimated before TACE were compared among CT/MRI, DSA and C arm CT imaging. Results: After TACE a total of 97 hypo-vascular tumors were found on CT scanning. The detection rates of hepatic tumors on CT/MRI, DSA and C arm CT imaging were 71.1% (69/97), 78.4% (76/97) and 89.7% (87/97), respectively, with P0.05. Conclusion: C arm CT imaging technique is superior to CT/MRI and DSA in detecting the hypo-vascular hepatic tumors. This technique can more precisely and more sensitively demonstrate the hepatic lesions, especially for the tumors with a diameter smaller than 10 mm. Therefore, this technique has great clinical value in treating hepatocellular carcinomas. (authors)

  18. Radiation doses in flat detector digital systems in Interventional Cardiology procedures

    International Nuclear Information System (INIS)

    The purpose of the study was to investigate patient radiation doses in flat detector (FD) digital X-ray systems in Interventional Cardiology procedures in three of the busiest haemodynamic departments in Greece and compare the results with the corresponding reference levels (RLs). Material and method: 569 Coronary Angiography (CA) and 571 Percutaneous Transluminal Coronary Angioplasties (PTCA) were investigated since these two procedures are the most frequently performed in haemodynamic units. Patient data collected were: sex, age, weight, height, Dose Area Product (DAP), fluoroscopy time (T) and total number of frames (F). Results: Median values of DAP and F in CA were: 31.0 Gycm2 and 752 in Hospital A, 35.3 Gycm2 and 487 in Hospital B and 21.1 Gycm2 and 461 in Hospital C. Median values of DAP and F in PTCA were: 63.2 Gycm2 and 1274 in Hospital A, 90.3 Gycm2 and 974 in Hospital B and 35.6 Gycm2 and 582 in Hospital C. Concerning T, the timer in Hospital C malfunctioned, whereas in hospitals A and B examination time was 4.7 and 3.6 min for CA and 10.3 and 12.7 min for PTCA, respectively. The results reveal a noted variability between hospitals especially in PTCA. However, patient dose values are lower than RLs (45 and 85 Gycm2 in CA and PTCA respectively). Conclusions: Large variations between patient dose values and main technical parameters were revealed when using FD digital systems in Greece. Dose optimization can be greatly achieved through continuous staff education in radiation protection issues. Moreover, the standardization of IC procedures in digital flat panel systems will definitely decrease patient and staff doses. (author)

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  5. Intravenous flat-detector CT angiography in acute ischemic stroke management

    Energy Technology Data Exchange (ETDEWEB)

    Blanc, Raphael; Pistocchi, Silvia; Bartolini, Bruno; Piotin, Michel [Fondation Rothschild Hospital, Department of Interventional Neuroradiology, Paris (France); Babic, Drazenko [Philips Healthcare, Best (Netherlands); Obadia, Michael [Fondation Rothschild Hospital, Department of Neurology, Paris (France); Alamowitch, Sonia [APHP Hopital Tenon, Universite Paris VI, Department of Neurology, Paris (France)

    2012-04-15

    In the settings of stroke, a non-invasive high-resolution imaging modality to visualize the arterial intracranial circulation in the interventional lab is a helpful mean to plan the endovascular recanalization procedure. We report our initial experience with intravenously enhanced flat-detector CT (IV FDCT) technology in the detection of obstructed intracranial arteries. Fourteen consecutive patients elected for endovascular stroke therapy underwent IV FDCT. The scans were intravenously enhanced and acquired in accordance with the previously calculated bolus arrival time. Images were processed on a commercially available workstation for reconstructions and 3D manipulation. Occlusion level and clot length, the quality of collateral vessels, and the patency of anterior and posterior communicating arteries were assessed. IV FDCT was performed successfully in all the cases and allowed for clot location and length visualization, assessment of communicating arteries patency, and evaluation of vessel collateral grade. Information obtained from this technique was considered useful for patients treated by endovascular approach. Retrospective review of the images by two independent readers was considered accurate and reproducible. IV FDCT technology provided accurate delineation of obstructed vessel segments in acute ischemic stroke disease. It gave a significant help in the interventional strategy. This new technology available in the operating room might provide a valuable tool in emerging endovascular stroke therapy. (orig.)

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

  9. Localisation using mini c-arm fluoroscopy of needles ingested by a woman with schizophrenia: a case report

    Directory of Open Access Journals (Sweden)

    Parlakgumus Alper

    2009-03-01

    Full Text Available Abstract Introduction Our aim was to specify the use of mini C-arm fluoroscopy in a woman with schizophrenia who was suffering from abdominal pain because of ingested needles. Case presentation Here we report the case of an 18-year-old Turkish woman with schizophrenia who was admitted to the emergency department with signs of an acute abdomen as a result of ingestion of multiple needles. This is the third case in the literature for which mini C-arm fluoroscopy has been used to localize metallic sewing needles. Conclusion When intentional ingestion occurs, surgery is rarely required. It is hard to localize ingested sewing needles and mini C-arm fluoroscopy is a good alternative when metal detectors are not available for localization of metal sewing needles. We recommend this approach because it helps to avoid unnecessary exploration, shortens the duration of surgery and provides outstanding results.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

  12. Development, implementation and evaluation of a dedicated metal artefact reduction method for interventional flat-detector CT

    OpenAIRE

    Prell, D; Kalender, W. A.; Kyriakou, Y

    2010-01-01

    The purpose of this study was to develop, implement and evaluate a dedicated metal artefact reduction (MAR) method for flat-detector CT (FDCT). The algorithm uses the multidimensional raw data space to calculate surrogate attenuation values for the original metal traces in the raw data domain. The metal traces are detected automatically by a three-dimensional, threshold-based segmentation algorithm in an initial reconstructed image volume, based on twofold histogram information for calculatin...

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

    International Nuclear Information System (INIS)

    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

  14. The value of flat-detector computed tomography during catheterisation of congenital heart disease

    Energy Technology Data Exchange (ETDEWEB)

    Gloeckler, Martin [University Hospital Erlangen, Department of Pediatric Cardiology, Erlangen (Germany); Friedrich-Alexander University Erlangen-Nuernberg, Department of Pediatric Cardiology, Erlangen (Germany); Koch, Andreas; Greim, Verena; Shabaiek, Amira; Dittrich, Sven [University Hospital Erlangen, Department of Pediatric Cardiology, Erlangen (Germany); Rueffer, Andre; Cesnjevar, Robert [University Hospital Erlangen, Department of Congenital Heart Surgery, Erlangen (Germany); Achenbach, Stephan [University Hospital Erlangen, Department of Cardiology, Erlangen (Germany)

    2011-12-15

    To analyse the diagnostic utility of flat-detector computed tomography imaging (FD-CT) in patients with congenital heart disease, including the value of image fusion to overlay three-dimensional (3D) reconstructions on fluoroscopic images during catheter-based interventions. We retrospectively analysed 62 consecutive paediatric patients in whom FD-CT was used during catheterisation of congenital heart disease. Expert operators rated the clinical value of FD-CT over conventional fluoroscopic imaging. Added radiation exposure and contrast medium volume were evaluated. During a 12-month period, FD-CT was performed in 62 out of 303 cardiac catheterisations. Median patient age was 3.5 years. In 32/62 cases, FD-CT was used for diagnostic purposes, in 30/62 cases it was used in the context of interventions. Diagnostic utility was never rated as ''misleading''. It was classified as ''not useful'' in six cases (9.7%), ''useful'' in 18 cases (29.0%), ''very useful'' in 37 cases (59.7%) and ''essential'' in one case (1.6%). The median added dose-area product was 111.0 {mu}Gym{sup 2}, the required additional quantity of contrast medium was 1.6 ml/kg. FD-CT provides useful diagnostic information in most of the patients investigated for congenital heart disease. The added radiation exposure and contrast medium volume are reasonable. (orig.)

  15. Radiation doses and estimated risk from angiographic projections during coronary angiography performed using novel flat detector.

    Science.gov (United States)

    Varghese, Anna; Livingstone, Roshan S; Varghese, Lijo; Kumar, Parveen; Srinath, Sirish Chandra; George, Oommen K; George, Paul V

    2016-01-01

    Coronary angiography (CA) procedure uses various angiographic projections to elicit detailed information of the coronary arteries with some steep projections involving high radiation dose to patients. This study intends to evaluate radiation doses and estimated risk from angiographic projections during CA procedure performed using novel flat detector (FD) system with improved image processing and noise reduction techniques. Real-time monitoring of radiation doses using kerma-area product (KAP) meter was performed for 140 patients using Philips Clarity FD system. The CA procedure involved seven standard projections, of which five were extensively selected by interventionalists. Mean fluoroscopic time (FT), KAP, and reference air kerma (Ka,r) for CA procedure were 3.24 min (0.5-10.51), 13.99Gycm2 (4.02-37.6), and 231.43 mGy (73.8-622.15), respectively. Effective dose calculated using Monte Carlo-based PCXMC software was found to be 4.9mSv. Left anterior oblique (LAO) 45° projection contributed the highest radiation dose (28%) of the overall KAP. Radiation-induced risk was found to be higher in females compared to males with increased risk of lung cancer. An increase of 10%-15% in radiation dose was observed when one or more additional projections were adopted along with the seven standard projections. A 14% reduction of radiation dose was achieved from novel FD system when low-dose protocol during fluoroscopy and medium-dose protocol during cine acquisitions were adopted, compared to medium-dose protocol. PMID:27167263

  16. Multimode C-arm fluoroscopy, tomosynthesis, and cone-beam CT for image-guided interventions: from proof of principle to patient protocols

    Science.gov (United States)

    Siewerdsen, J. H.; Daly, M. J.; Bachar, G.; Moseley, D. J.; Bootsma, G.; Brock, K. K.; Ansell, S.; Wilson, G. A.; Chhabra, S.; Jaffray, D. A.; Irish, J. C.

    2007-03-01

    High-performance intraoperative imaging is essential to an ever-expanding scope of therapeutic procedures ranging from tumor surgery to interventional radiology. The need for precise visualization of bony and soft-tissue structures with minimal obstruction to the therapy setup presents challenges and opportunities in the development of novel imaging technologies specifically for image-guided procedures. Over the past ~5 years, a mobile C-arm has been modified in collaboration with Siemens Medical Solutions for 3D imaging. Based upon a Siemens PowerMobil, the device includes: a flat-panel detector (Varian PaxScan 4030CB); a motorized orbit; a system for geometric calibration; integration with real-time tracking and navigation (NDI Polaris); and a computer control system for multi-mode fluoroscopy, tomosynthesis, and cone-beam CT. Investigation of 3D imaging performance (noise-equivalent quanta), image quality (human observer studies), and image artifacts (scatter, truncation, and cone-beam artifacts) has driven the development of imaging techniques appropriate to a host of image-guided interventions. Multi-mode functionality presents a valuable spectrum of acquisition techniques: i.) fluoroscopy for real-time 2D guidance; ii.) limited-angle tomosynthesis for fast 3D imaging (e.g., ~10 sec acquisition of coronal slices containing the surgical target); and iii.) fully 3D cone-beam CT (e.g., ~30-60 sec acquisition providing bony and soft-tissue visualization across the field of view). Phantom and cadaver studies clearly indicate the potential for improved surgical performance - up to a factor of 2 increase in challenging surgical target excisions. The C-arm system is currently being deployed in patient protocols ranging from brachytherapy to chest, breast, spine, and head and neck surgery.

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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.

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

    OpenAIRE

    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...

  2. A novel flat-response x-ray detector in the photon energy range of 0.1-4 keV

    International Nuclear Information System (INIS)

    A novel flat-response x-ray detector has been developed for the measurement of radiation flux from a hohlraum. In order to obtain a flat response in the photon energy range of 0.1-4 keV, it is found that both the cathode and the filter of the detector can be made of gold. A further improvement on the compound filter can then largely relax the requirement of the calibration x-ray beam. The calibration of the detector, which is carried out on Beijing Synchrotron Radiation Facility at Institute of High Energy Physics, shows that the detector has a desired flat response in the photon energy range of 0.1-4 keV, with a response flatness smaller than 13%. The detector has been successfully applied in the hohlraum experiment on Shenguang-III prototype laser facility. The radiation temperatures inferred from the detector agree well with those from the diagnostic instrument Dante installed at the same azimuth angle from the hohlraum axis, demonstrating the feasibility of the detector.

  3. C-arm guided closed reduction of zygomatic arch fracture

    International Nuclear Information System (INIS)

    The zygomatic arch is structurally protruded and is easily fractured. The classic management of zygomatic arch fracture has been mentioned the Keen, Lothrop, Dingman and Alling and threaded K-wire. All of the above methods have advantages and disadvantages. To minimize the disadvantages, we performed threaded K-wire for the first time using C-arm image intensifier. The subjects were 16 patients with Knight North group II (Zygomatic arch fracture). Among them the C-arm was used in 12 patients and the operator used sensitivity general method in 4 patients and confirmed the operation by mobile X-ray equipment. In conclusion, both groups were satisfied surgically and cosmetically. Using the C-arm, actual image at the time operation was clear and satisfied, the surrounding tissue damage was minimized and at was more accurately completed. The operation time was shortened by 30 to 60 minutes proving it to be an efficient method. We suggest though that further studies be needed to evaluate the radiation effect on these patients

  4. Unruh-DeWitt detector's response to fermions in flat spacetimes

    CERN Document Server

    Louko, Jorma

    2016-01-01

    We examine an Unruh-DeWitt particle detector that is coupled linearly to the scalar density of a massless Dirac field in Minkowski spacetimes of dimension $d\\ge2$ and on the static Minkowski cylinder in spacetime dimension two, allowing the detector's motion to remain arbitrary and working to leading order in perturbation theory. In $d$-dimensional Minkowski, with the field in the usual Fock vacuum, we show that the detector's response is identical to that of a detector coupled linearly to a massless scalar field in $2d$-dimensional Minkowski. In the special case of uniform linear acceleration, the detector's response hence exhibits the Unruh effect with a Planckian factor in both even and odd dimensions, in contrast to the Rindler power spectrum of the Dirac field, which has a Planckian factor for odd $d$ but a Fermi-Dirac factor for even~$d$. On the two-dimensional cylinder, we set the oscillator modes in the usual Fock vacuum but allow an arbitrary state for the zero mode of the periodic spinor. We show th...

  5. Evaluation of Flat Microchannel Plate Photomultipliers for Use in a Portable Air Fluorescence Detector

    Science.gov (United States)

    Benzvi, S.; Martin, J.

    2003-07-01

    Future applications of the air fluorescence technique will require robust, portable detectors, versatile enough to be deployed in remote areas with little infrastructure. One such experiment is the Gamma Ray and Neutron Decay Scan of the Galaxy (GRaNDScan), which proposes to survey the EeV sky by observation of γ and cosmic ray air showers in the southern hemisphere. To view a 30° field at or exceeding a resolution of 1° , GRaNDScan will employ a lensless Schmidt optical system, with the light-sensitive element in each detector consisting of a spherical surface of tiled photomultipliers. Currently, the BURLE 85001 micro channel plate photomultiplier (MCP PMT), a low profile device appropriate for tiling, is the primary candidate for these cameras. In this paper, we discuss the preliminary design of the GRaNDScan optics, the basic characteristics of the 85001 photomultiplier, and the suitability of this device for use in a portable air fluorescence detector.

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

    Energy Technology Data Exchange (ETDEWEB)

    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)

  7. Cone-beam breast computed tomography with a displaced flat panel detector array

    Energy Technology Data Exchange (ETDEWEB)

    Mettivier, Giovanni; Russo, Paolo; Lanconelli, Nico; Meo, Sergio Lo [Universita di Napoli Federico II, Dipartimento di Scienze Fisiche, and INFN, Sezione di Napoli, I-80126 Napoli (Italy); Alma Mater Studiorum-Universita di Bologna, Dipartimento di Fisica, and INFN, Sezione di Bologna, I-40127 Bologna (Italy)

    2012-05-15

    Purpose: In cone-beam computed tomography (CBCT), and in particular in cone-beam breast computed tomography (CBBCT), an important issue is the reduction of the image artifacts produced by photon scatter and the reduction of patient dose. In this work, the authors propose to apply the detector displacement technique (also known as asymmetric detector or ''extended view'' geometry) to approach this goal. Potentially, this type of geometry, and the accompanying use of a beam collimator to mask the unirradiated half-object in each projection, permits some reduction of radiation dose with respect to conventional CBBCT and a sizeable reduction of the overall amount of scatter in the object, for a fixed contrast-to-noise ratio (CNR). Methods: The authors consider a scan configuration in which the projection data are acquired from an asymmetrically positioned detector that covers only one half of the scan field of view. Monte Carlo simulations and measurements, with their CBBCT laboratory scanner, were performed using PMMA phantoms of cylindrical (70-mm diameter) and hemiellipsoidal (140-mm diameter) shape simulating the average pendant breast, at 80 kVp. Image quality was evaluated in terms of contrast, noise, CNR, contrast-to-noise ratio per unit of dose (CNRD), and spatial resolution as width of line spread function for high contrast details. Results: Reconstructed images with the asymmetric detector technique deviate less than 1% from reconstruction with a conventional symmetric detector (detector view) and indicate a reduction of the cupping artifact in CT slices. The maximum scatter-to-primary ratio at the center of the phantom decreases by about 50% for both small and large diameter phantoms (e.g., from 0.75 in detector view to 0.40 in extended view geometry at the central axis of the 140-mm diameter PMMA phantom). Less cupping produces an increase of the CT number accuracy and an improved image detail contrast, but the associated increase of

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

    Science.gov (United States)

    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

  9. Developing low-dose C-arm CT imaging for temporomandibular joint (TMJ) disorder in interventional radiology

    International Nuclear Information System (INIS)

    Manufacturers have provided C-arm CT imaging technologies for applications in interventional radiology in recent years. However, clinical imaging protocols and radiation doses have not been well studied or reported. The purpose of this study is to develop low-dose settings for clinically acceptable CT imaging of temporomandibular joint in interventional radiology suites, using a C-arm imaging angiography system. CT scans were performed with a flat-panel digital C-arm angiographic system on a 5-year-old anthropomorphic phantom. The CTDI was determined for various rotation times, dose settings and Cu filter selections. The CTDI values were compared with those of conventional low-dose CT for the same phantom. The effectiveness of using Cu filters to reduce dose was also investigated. Images were reviewed by a senior radiologist for clinical acceptance. The manufacturer's default setting gave an equivalent CTDI of 4.8 mGy. Optimizing the dose settings and adding copper filtration reduced the radiation dose by 94%. This represents a 50% reduction from conventional CT. Use of Cu filters and low-dose settings significantly reduced radiation dose from that of standard settings. This phantom study process successfully guided the clinical implementation of low-dose studies for all ages at our institution. (orig.)

  10. Developing low-dose C-arm CT imaging for temporomandibular joint (TMJ) disorder in interventional radiology

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xiaowei; Cahill, Anne Marie [Children' s Hospital of Philadelphia, Department of Radiology, Philadelphia, PA (United States); Felice, Marc [University of Pennsylvania, Environmental Health and Radiation Safety, Philadelphia, PA (United States); Johnson, Laura [Computed Tomography Division, Siemens Healthcare Sector, Shanghai (China); Sarmiento, Marily [Siemens Medical Solutions, Angiography and X-ray Division, Hoffman Estates, IL (United States)

    2011-04-15

    Manufacturers have provided C-arm CT imaging technologies for applications in interventional radiology in recent years. However, clinical imaging protocols and radiation doses have not been well studied or reported. The purpose of this study is to develop low-dose settings for clinically acceptable CT imaging of temporomandibular joint in interventional radiology suites, using a C-arm imaging angiography system. CT scans were performed with a flat-panel digital C-arm angiographic system on a 5-year-old anthropomorphic phantom. The CTDI was determined for various rotation times, dose settings and Cu filter selections. The CTDI values were compared with those of conventional low-dose CT for the same phantom. The effectiveness of using Cu filters to reduce dose was also investigated. Images were reviewed by a senior radiologist for clinical acceptance. The manufacturer's default setting gave an equivalent CTDI of 4.8 mGy. Optimizing the dose settings and adding copper filtration reduced the radiation dose by 94%. This represents a 50% reduction from conventional CT. Use of Cu filters and low-dose settings significantly reduced radiation dose from that of standard settings. This phantom study process successfully guided the clinical implementation of low-dose studies for all ages at our institution. (orig.)

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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

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

    International Nuclear Information System (INIS)

    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

  15. The flat fielding and achievable signal-to-noise of the MAMA detectors

    Science.gov (United States)

    Kaiser, Mary Elizabeth; Lindler, Don J.; Bohlin, Ralph C.

    1997-01-01

    The Space Telescope Imaging Spectrograph (STIS) was designed to achieve a signal-to-noise (S/N) of at least 100:1 per resolution element. Multi-Anode Microchannel Arrays (MAMA) observations during Servicing Mission Orbital Verification (SMOV) confirm that this specification can be met. From analysis of a single spectrum of GD153, with counting statistics of approximately 165 a S/N of approximately 125 is achieved per spectral resolution element in the far ultraviolet (FUV) over the spectral range of 1280A to 1455A. Co-adding spectra of GRW+7OD5824 to increase the counting statistics to approximately 300 yields a S/N of approximately 190 per spectral resolution element over the region extending from 1347A to 1480A in the FUV. In the near ultraviolet (NUV), a single spectrum of GRW+7OD5824 with counting statistics of approximately 200 yields a S/N of approximately 150 per spectral resolution element over the spectral region extending from 2167 to 2520A. Details of the flat field construction, the spectral extraction, and the definition of a spectral resolution element will be described in the text.

  16. Assessment of Lumbar Spine Instability Using C-Arm Fluoroscopy.

    Science.gov (United States)

    Temes, Bill; Karas, Steve; Manwill, James

    2016-09-01

    A 47-year-old woman was referred to physical therapy with a diagnosis of lumbar radiculopathy. Weight-bearing flexion/extension radiographs showed no change in a 13-mm (at L5-S1) spondylolisthesis measured with a neutral posture. Physical therapy with a focus on flexion-biased stabilization exercises was initiated. After failing to improve after 6 weeks, her referring physician ordered magnetic resonance imaging, which revealed a 6-mm spondylolisthesis in a supine position. Additionally, the physical therapist performed an anterior stability test of L5 on S1 under C-arm fluoroscopy, which demonstrated a palpable shift of S1 posteriorly that was measured on imaging as a change from a 13-mm to a 17-mm spondylolisthesis. J Orthop Sports Phys Ther 2016;46(9):810. doi:10.2519/jospt.2016.0415. PMID:27581181

  17. A comparison of reconstruction algorithms for C-arm mammography tomosynthesis

    International Nuclear Information System (INIS)

    Digital tomosynthesis is an imaging technique to produce a tomographic image from a series of angular digital images in a manner similar to conventional focal plane tomography. Unlike film focal plane tomography, the acquisition of the data in a C-arm geometry causes the image receptor to be positioned at various angles to the reconstruction tomogram. The digital nature of the data allows for input images to be combined into the desired plane with the flexibility of generating tomograms of many separate planes from a single set of input data. Angular datasets were obtained of a low contrast detectability (LCD) phantom and cadaver breast utilizing a Lorad stereotactic biopsy unit with a coupled source and digital detector in a C-arm configuration. Datasets of 9 and 41 low-dose projections were collected over a 30 deg. angular range. Tomographic images were reconstructed using a Backprojection (BP) algorithm, an Iterative Subtraction (IS) algorithm that allows the partial subtraction of out-of-focus planes, and an Algebraic Reconstruction (AR) algorithm. These were compared with single view digital radiographs. The methods' effectiveness at enhancing visibility of an obscured LCD phantom was quantified in terms of the Signal to Noise Ratio (SNR), and Signal to Background Ratio (SBR), all normalized to the metric value for the single projection image. The methods' effectiveness at removing ghosting artifacts in a cadaver breast was quantified in terms of the Artifact Spread Function (ASF). The technology proved effective at partially removing out of focus structures and enhancing SNR and SBR. The normalized SNR was highest at 4.85 for the obscured LCD phantom, using nine projections and IS algorithm. The normalized SBR was highest at 23.2 for the obscured LCD phantom, using 41 projections and an AR algorithm. The highest normalized metric values occurred with the obscured phantom. This supports the assertion that the greatest value of tomosynthesis is in imaging

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

    Science.gov (United States)

    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

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

    International Nuclear Information System (INIS)

    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

  20. A fast and pragmatic approach for scatter correction in flat-detector CT using elliptic modeling and iterative optimization

    International Nuclear Information System (INIS)

    Scattered radiation is a major source of artifacts in flat detector computed tomography (FDCT) due to the increased irradiated volumes. We propose a fast projection-based algorithm for correction of scatter artifacts. The presented algorithm combines a convolution method to determine the spatial distribution of the scatter intensity distribution with an object-size-dependent scaling of the scatter intensity distributions using a priori information generated by Monte Carlo simulations. A projection-based (PBSE) and an image-based (IBSE) strategy for size estimation of the scanned object are presented. Both strategies provide good correction and comparable results; the faster PBSE strategy is recommended. Even with such a fast and simple algorithm that in the PBSE variant does not rely on reconstructed volumes or scatter measurements, it is possible to provide a reasonable scatter correction even for truncated scans. For both simulations and measurements, scatter artifacts were significantly reduced and the algorithm showed stable behavior in the z-direction. For simulated voxelized head, hip and thorax phantoms, a figure of merit Q of 0.82, 0.76 and 0.77 was reached, respectively (Q = 0 for uncorrected, Q = 1 for ideal). For a water phantom with 15 cm diameter, for example, a cupping reduction from 10.8% down to 2.1% was achieved. The performance of the correction method has limitations in the case of measurements using non-ideal detectors, intensity calibration, etc. An iterative approach to overcome most of these limitations was proposed. This approach is based on root finding of a cupping metric and may be useful for other scatter correction methods as well. By this optimization, cupping of the measured water phantom was further reduced down to 0.9%. The algorithm was evaluated on a commercial system including truncated and non-homogeneous clinically relevant objects.

  1. A fast and pragmatic approach for scatter correction in flat-detector CT using elliptic modeling and iterative optimization

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Michael; Kalender, Willi A; Kyriakou, Yiannis [Institute of Medical Physics, University of Erlangen-Nuernberg (Germany)], E-mail: michael.meyer@imp.uni-erlangen.de

    2010-01-07

    Scattered radiation is a major source of artifacts in flat detector computed tomography (FDCT) due to the increased irradiated volumes. We propose a fast projection-based algorithm for correction of scatter artifacts. The presented algorithm combines a convolution method to determine the spatial distribution of the scatter intensity distribution with an object-size-dependent scaling of the scatter intensity distributions using a priori information generated by Monte Carlo simulations. A projection-based (PBSE) and an image-based (IBSE) strategy for size estimation of the scanned object are presented. Both strategies provide good correction and comparable results; the faster PBSE strategy is recommended. Even with such a fast and simple algorithm that in the PBSE variant does not rely on reconstructed volumes or scatter measurements, it is possible to provide a reasonable scatter correction even for truncated scans. For both simulations and measurements, scatter artifacts were significantly reduced and the algorithm showed stable behavior in the z-direction. For simulated voxelized head, hip and thorax phantoms, a figure of merit Q of 0.82, 0.76 and 0.77 was reached, respectively (Q = 0 for uncorrected, Q = 1 for ideal). For a water phantom with 15 cm diameter, for example, a cupping reduction from 10.8% down to 2.1% was achieved. The performance of the correction method has limitations in the case of measurements using non-ideal detectors, intensity calibration, etc. An iterative approach to overcome most of these limitations was proposed. This approach is based on root finding of a cupping metric and may be useful for other scatter correction methods as well. By this optimization, cupping of the measured water phantom was further reduced down to 0.9%. The algorithm was evaluated on a commercial system including truncated and non-homogeneous clinically relevant objects.

  2. Dental Implant Placement using C-arm CT Real Time Imaging System: A Case Report

    OpenAIRE

    Rajkumar, B.; Lalit C Boruah; Thind, Amandeep; Jain, Gaurav; Gupta, Shilpi

    2014-01-01

    C-arm computed tomography (CT) is a new and innovative imaging technique. In combination with two-dimensional fluoroscopic or radiographic imaging, information provided by three-dimensional C-arm real time imaging can be valuable for therapy planning, guidance and outcome assessment in dental implant placement. This paper reports a case of two dental implant placement using Artis zee C-arm CT system first time in field of implantology.

  3. C-arm CT-guided 3D navigation of percutaneous interventions

    International Nuclear Information System (INIS)

    So far C-arm CT images were predominantly used for a precise guidance of an endovascular or intra-arterial therapy. A novel combined 3D-navigation C-arm system now also allows cross-sectional and fluoroscopy controlled interventions. Studies have reported about successful CT-image guided navigation with C-arm systems in vertebroplasty. Insertion of the radiofrequency ablation probe is also conceivable for lung and liver tumors that had been labelled with lipiodol. In the future C-arm CT based navigation systems will probably allow simplified and safer complex interventions and simultaneously reduce radiation exposure. (orig.)

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

    Science.gov (United States)

    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

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

    International Nuclear Information System (INIS)

    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)

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  10. Surgical screw segmentation for mobile C-arm CT devices

    Science.gov (United States)

    Görres, Joseph; Brehler, Michael; Franke, Jochen; Wolf, Ivo; Vetter, Sven Y.; Grützner, Paul A.; Meinzer, Hans-Peter; Nabers, Diana

    2014-03-01

    Calcaneal fractures are commonly treated by open reduction and internal fixation. An anatomical reconstruction of involved joints is mandatory to prevent cartilage damage and premature arthritis. In order to avoid intraarticular screw placements, the use of mobile C-arm CT devices is required. However, for analyzing the screw placement in detail, a time-consuming human-computer interaction is necessary to navigate through 3D images and therefore to view a single screw in detail. Established interaction procedures of repeatedly positioning and rotating sectional planes are inconvenient and impede the intraoperative assessment of the screw positioning. To simplify the interaction with 3D images, we propose an automatic screw segmentation that allows for an immediate selection of relevant sectional planes. Our algorithm consists of three major steps. At first, cylindrical characteristics are determined from local gradient structures with the help of RANSAC. In a second step, a DBScan clustering algorithm is applied to group similar cylinder characteristics. Each detected cluster represents a screw, whose determined location is then refined by a cylinder-to-image registration in a third step. Our evaluation with 309 screws in 50 images shows robust and precise results. The algorithm detected 98% (303) of the screws correctly. Thirteen clusters led to falsely identified screws. The mean distance error for the screw tip was 0.8 +/- 0.8 mm and for the screw head 1.2 +/- 1 mm. The mean orientation error was 1.4 +/- 1.2 degrees.

  11. Usefulness of C-arm CT during superselective infusion chemotherapy for advanced head and neck carcinoma

    International Nuclear Information System (INIS)

    To evaluate the usefulness of C-arm computed tomography (CT) during superselective intra-arterial infusion chemotherapy for advanced head and neck carcinoma. C-arm CT was performed during superselective intra-arterial infusion chemotherapy for 11 patients with advanced head and neck carcinoma located in the hypopharynx (n = 3), maxillary sinus (n = 3), oropharynx (n = 1), larynx (n = 1), extra-auditory canal (n = 1), tonsil (n = 1) and tongue (n = 1). The usefulness of C-arm CT during superselective catheterisation was evaluated. On arteriography, nine tumours showed tumour stains and two in the oropharynx or tonsil showed no obvious tumour stains. C-arm CT was performed one to four times (mean ± standard deviation, 2.5 ± 0.8) in each patient during a single procedure. C-arm CT clearly showed not only the vascular territory of the selected branch but also the tumour itself in all patients. Intra-arterial infusion chemotherapy was performed through one to three branches (mean, 1.7 ± 0.9) according to C-arm CT findings without any complications. C-arm CT during superselective intra-arterial infusion chemotherapy was useful to determine the arterial supply of head and neck carcinoma. C-arm CT may replace conventional CT during superselective arteriography in this procedure.

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

    International Nuclear Information System (INIS)

    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.)

  13. Flat detector computed tomography in diagnostic and interventional pediatric cardiology; Flachdetektor-Computertomografie in der diagnostischen und interventionellen Kinderkardiologie

    Energy Technology Data Exchange (ETDEWEB)

    Moesler, J.; Dittrich, S.; Gloeckler, M. [Erlangen-Nuernberg Univ., Erlangen (Germany). Pediatric Cardiology; Rompel, O. [Erlangen-Nuernberg Univ., Erlangen (Germany). Radiology

    2013-05-15

    Purpose: In this study the use of flat detector computed tomography (FD-CT) in the catheterization of patients with congenital heart disease was evaluated. Application reports were created for various issues based on the achieved image quality in diverse anatomical regions. Materials and Methods: FD-CT was applied in 176 cases during catheterization between January 2010 and April 2012. A five-point Likert scale ('essential' to 'misleading') was used to evaluate image quality. All cases were analyzed retrospectively and application reports for the visualization of the aorta, pulmonary arteries, pulmonary veins, semilunar valves, cavopulmonary connections and atrial baffles were generated. Contrast dye consumption and radiation dose were evaluated. Results: During the observation period FD-CT was applied in all 176 cases. The mean patient age was 7.0 years (0.01 - 42.53 years). The clinical value of FD-CT was rated superior to conventional angiography in 96.6 % of the cases and was never rated as 'misleading'. FD-CT was rated 'essential' in 3.4 % of all cases, 'very useful' in 77.3 % of all cases, 'useful' in 15.9 % of all cases and 'not useful' in 3.4 % of all cases. The mean dose-area product was 99 {mu}Gym{sup 2} (19.3 - 1276.6 {mu}Gym{sup 2}), and the used contrast dye was 1.76 ml/kg (0.9 - 5 ml/kg). Application reports for the visualization of different anatomical regions are demonstrated. Conclusion: FD-CT is a new and auxiliary procedure in diagnostic and interventional catheterization of patients with congenital heart disease. Particularly extracardiac structures can be displayed in three-dimensional high resolution and be used for diagnosis, surgical planning and 3 D navigation. (orig.)

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

    International Nuclear Information System (INIS)

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

  15. Flat-detector computed tomography evaluation in an experimental animal aneurysm model after endovascular treatment: A pilot study.

    Science.gov (United States)

    Ott, Sabine; Gölitz, Philipp; Adamek, Edyta; Royalty, Kevin; Doerfler, Arnd; Struffert, Tobias

    2015-08-01

    We compared flat-detector computed tomography angiography (FD-CTA) to multislice computed tomography (MS-CTA) and digital subtracted angiography (DSA) for the visualization of experimental aneurysms treated with stents, coils or a combination of both.In 20 rabbits, aneurysms were created using the rabbit elastase aneurysm model. Seven aneurysms were treated with coils, seven with coils and stents, and six with self-expandable stents alone. Imaging was performed by DSA, MS-CTA and FD-CTA immediately after treatment. Multiplanar reconstruction (MPR) was performed and two experienced reviewers compared aneurysm/coil package size, aneurysm occlusion, stent diameters and artifacts for each modality.In aneurysms treated with stents alone, the visualization of the aneurysms was identical in all three imaging modalities. Residual aneurysm perfusion was present in two cases and visible in DSA and FD-CTA but not in MS-CTA. The diameter of coil-packages was overestimated in MS-CT by 56% and only by 16% in FD-CTA compared to DSA (p metal hardening artifacts impaired image quality more severely in MS-CTA compared to FD-CTA.MS-CTA is impaired by blooming and beam/metal hardening artifacts in the visualization of implanted devices. There was no significant difference between measurements made with noninvasive FD-CTA compared to gold standard of DSA after stenting and after coiling/stent-assisted coiling of aneurysms. FD-CTA may be considered as a non-invasive alternative to the gold standard 2D DSA in selected patients that require follow up imaging after stenting. PMID:26111985

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

    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

  18. DIRAC detector experiment: the vacuum chamber (blue), beginning of the flat chamber (yellow), magnetic screen (orange) in front of the magnet. The vacuum tube for the primary proton beam is below (sil ver color)

    CERN Multimedia

    Patrice Loïez

    1999-01-01

    DIRAC detector experiment: the vacuum chamber (blue), beginning of the flat chamber (yellow), magnetic screen (orange) in front of the magnet. The vacuum tube for the primary proton beam is below (sil ver color)

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

    Science.gov (United States)

    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.

  20. Mobile C-arm cone-beam CT for guidance of spine surgery: Image quality, radiation dose, and integration with interventional guidance

    Energy Technology Data Exchange (ETDEWEB)

    Schafer, S.; Nithiananthan, S.; Mirota, D. J.; Uneri, A.; Stayman, J. W.; Zbijewski, W.; Schmidgunst, C.; Kleinszig, G.; Khanna, A. J.; Siewerdsen, J. H. [Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21202 (United States); Department of Computer Science, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21202 (United States); Siemens Healthcare XP Division, Erlangen (Germany); Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, Maryland 21239 (United States); Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21202 and Department of Computer Science, Johns Hopkins University, Baltimore, Maryland 21218 (United States)

    2011-08-15

    Purpose: A flat-panel detector based mobile isocentric C-arm for cone-beam CT (CBCT) has been developed to allow intraoperative 3D imaging with sub-millimeter spatial resolution and soft-tissue visibility. Image quality and radiation dose were evaluated in spinal surgery, commonly relying on lower-performance image intensifier based mobile C-arms. Scan protocols were developed for task-specific imaging at minimum dose, in-room exposure was evaluated, and integration of the imaging system with a surgical guidance system was demonstrated in preclinical studies of minimally invasive spine surgery. Methods: Radiation dose was assessed as a function of kilovolt (peak) (80-120 kVp) and milliampere second using thoracic and lumbar spine dosimetry phantoms. In-room radiation exposure was measured throughout the operating room for various CBCT scan protocols. Image quality was assessed using tissue-equivalent inserts in chest and abdomen phantoms to evaluate bone and soft-tissue contrast-to-noise ratio as a function of dose, and task-specific protocols (i.e., visualization of bone or soft-tissues) were defined. Results were applied in preclinical studies using a cadaveric torso simulating minimally invasive, transpedicular surgery. Results: Task-specific CBCT protocols identified include: thoracic bone visualization (100 kVp; 60 mAs; 1.8 mGy); lumbar bone visualization (100 kVp; 130 mAs; 3.2 mGy); thoracic soft-tissue visualization (100 kVp; 230 mAs; 4.3 mGy); and lumbar soft-tissue visualization (120 kVp; 460 mAs; 10.6 mGy) - each at (0.3 x 0.3 x 0.9 mm{sup 3}) voxel size. Alternative lower-dose, lower-resolution soft-tissue visualization protocols were identified (100 kVp; 230 mAs; 5.1 mGy) for the lumbar region at (0.3 x 0.3 x 1.5 mm{sup 3}) voxel size. Half-scan orbit of the C-arm (x-ray tube traversing under the table) was dosimetrically advantageous (prepatient attenuation) with a nonuniform dose distribution ({approx}2 x higher at the entrance side than at isocenter

  1. Mobile C-arm cone-beam CT for guidance of spine surgery: Image quality, radiation dose, and integration with interventional guidance

    International Nuclear Information System (INIS)

    Purpose: A flat-panel detector based mobile isocentric C-arm for cone-beam CT (CBCT) has been developed to allow intraoperative 3D imaging with sub-millimeter spatial resolution and soft-tissue visibility. Image quality and radiation dose were evaluated in spinal surgery, commonly relying on lower-performance image intensifier based mobile C-arms. Scan protocols were developed for task-specific imaging at minimum dose, in-room exposure was evaluated, and integration of the imaging system with a surgical guidance system was demonstrated in preclinical studies of minimally invasive spine surgery. Methods: Radiation dose was assessed as a function of kilovolt (peak) (80-120 kVp) and milliampere second using thoracic and lumbar spine dosimetry phantoms. In-room radiation exposure was measured throughout the operating room for various CBCT scan protocols. Image quality was assessed using tissue-equivalent inserts in chest and abdomen phantoms to evaluate bone and soft-tissue contrast-to-noise ratio as a function of dose, and task-specific protocols (i.e., visualization of bone or soft-tissues) were defined. Results were applied in preclinical studies using a cadaveric torso simulating minimally invasive, transpedicular surgery. Results: Task-specific CBCT protocols identified include: thoracic bone visualization (100 kVp; 60 mAs; 1.8 mGy); lumbar bone visualization (100 kVp; 130 mAs; 3.2 mGy); thoracic soft-tissue visualization (100 kVp; 230 mAs; 4.3 mGy); and lumbar soft-tissue visualization (120 kVp; 460 mAs; 10.6 mGy) - each at (0.3 x 0.3 x 0.9 mm3) voxel size. Alternative lower-dose, lower-resolution soft-tissue visualization protocols were identified (100 kVp; 230 mAs; 5.1 mGy) for the lumbar region at (0.3 x 0.3 x 1.5 mm3) voxel size. Half-scan orbit of the C-arm (x-ray tube traversing under the table) was dosimetrically advantageous (prepatient attenuation) with a nonuniform dose distribution (∼2 x higher at the entrance side than at isocenter, and ∼3-4 lower

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

    International Nuclear Information System (INIS)

    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

  3. Image quality and localization accuracy in C-arm tomosynthesis-guided head and neck surgery

    International Nuclear Information System (INIS)

    The image quality and localization accuracy for C-arm tomosynthesis and cone-beam computed tomography (CBCT) guidance of head and neck surgery were investigated. A continuum in image acquisition was explored, ranging from a single exposure (radiograph) to multiple projections acquired over a limited arc (tomosynthesis) to a full semicircular trajectory (CBCT). Experiments were performed using a prototype mobile C-arm modified to perform 3D image acquisition (a modified Siemens PowerMobil). The tradeoffs in image quality associated with the extent of the source-detector arc (θtot), the number of projection views, and the total imaging dose were evaluated in phantom and cadaver studies. Surgical localization performance was evaluated using three cadaver heads imaged as a function of θtot. Six localization tasks were considered, ranging from high-contrast feature identification (e.g., tip of a K-wire pointer) to more challenging soft-tissue delineation (e.g., junction of the hard and soft palate). Five head and neck surgeons and one radiologist participated as observers. For each localization task, the 3D coordinates of landmarks pinpointed by each observer were analyzed as a function of θtot. For all tomosynthesis angles, image quality was highest in the coronal plane, whereas sagittal and axial planes exhibited a substantial decrease in spatial resolution associated with out-of-plane blur and distortion. Tasks involving complex, lower-contrast features demonstrated steeper degradation with smaller tomosynthetic arc. Localization accuracy in the coronal plane was correspondingly high, maintained to tot∼30 deg. , whereas sagittal and axial localization degraded rapidly below θtot∼60 deg. . Similarly, localization precision was better than ∼1 mm within the coronal plane, compared to ∼2-3 mm out-of-plane for tomosynthesis angles below θtot∼45 deg. . An overall 3D localization accuracy of ∼2.5 mm was achieved with θtot∼ 90 deg. for most tasks. The

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

    Energy Technology Data Exchange (ETDEWEB)

    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.)

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

    International Nuclear Information System (INIS)

    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)

  6. Marker detection evaluation by phantom and cadaver experiments for C-arm pose estimation pattern

    Science.gov (United States)

    Steger, Teena; Hoßbach, Martin; Wesarg, Stefan

    2013-03-01

    C-arm fluoroscopy is used for guidance during several clinical exams, e.g. in bronchoscopy to locate the bronchoscope inside the airways. Unfortunately, these images provide only 2D information. However, if the C-arm pose is known, it can be used to overlay the intrainterventional fluoroscopy images with 3D visualizations of airways, acquired from preinterventional CT images. Thus, the physician's view is enhanced and localization of the instrument at the correct position inside the bronchial tree is facilitated. We present a novel method for C-arm pose estimation introducing a marker-based pattern, which is placed on the patient table. The steel markers form a pattern, allowing to deduce the C-arm pose by use of the projective invariant cross-ratio. Simulations show that the C-arm pose estimation is reliable and accurate for translations inside an imaging area of 30 cm x 50 cm and rotations up to 30°. Mean error values are 0.33 mm in 3D space and 0.48 px in the 2D imaging plane. First tests on C-arm images resulted in similarly compelling accuracy values and high reliability in an imaging area of 30 cm x 42.5 cm. Even in the presence of interfering structures, tested both with anatomy phantoms and a turkey cadaver, high success rates over 90% and fully satisfying execution times below 4 sec for 1024 px × 1024 px images could be achieved.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  8. A compact flat-response x-ray detector for the radiation flux in the range from 1.6 keV to 4.4 keV

    International Nuclear Information System (INIS)

    A band-pass flat-response x-ray detector is designed to measure the absolute M-band x-ray flux. The detector comprises an x-ray diode and a compound filter that is carefully designed to achieve the desired response function in the range from 1.6 to 4.4 keV, i.e. the flatness of the spectral response is better than 5%. The designed response function is in excellent agreement with the calibrated one, indicating that the x-ray detector with various responses can be achieved with the state-of-art fabrication technique. (paper)

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

    Science.gov (United States)

    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

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

    OpenAIRE

    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...

  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

    International Nuclear Information System (INIS)

    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. Utility of intraoperative diagnostic C-arm angiography for management of high grade subarachnoid hemorrhage

    Directory of Open Access Journals (Sweden)

    Zhikui Wei

    2015-06-01

    Full Text Available The accurate and efficient localization of underlying vascular lesions is crucial for prompt and definitive treatment of subarachnoid hemorrhage (SAH. To demonstrate the utility and feasibility of intraoperative C-arm angiography in cerebrovascular emergencies, we report five cases of high grade SAH and/or intracerebral hemorrhage (ICH where intraoperative diagnostic C-arm angiography was safely and effectively utilized. Initial evaluations of all patients included a non-contrast head CT scan, which was followed by urgent decompressive hemicraniectomy as a life-saving measure in the presence of markedly elevated intracranial pressure. Further diagnostic evaluations were performed intraoperatively using a multi-purpose C-arm angiography system. The C-arm angiography findings greatly aided the intraoperative planning and led to definitive treatments in four cases of SAH by elucidating the underlying neurovascular lesions. With this treatment strategy, two of the patients made moderately good recoveries from their SAH and/or ICH with a Glasgow outcome score (GOS of 4. Three of the patients expired despite maximal therapy mostly due to unfavorable presenting grade. These results suggest that C-arm angiography is a reasonable diagnostic and surgical planning tool for selected patients with high grade diffuse SAH who require immediate decompression.

  13. Polycarbonate track detectors with a flat energy response for the measurement of high energy neutrons at accelerators and airflight altitudes

    International Nuclear Information System (INIS)

    For the polycarbonate detector routinely used at FZK, the two-step electrochemical etching was finally optimised after changing the detector thickness from 300 μm to 500 μm and applying a field strength of 42 kV.cm-1. On the basis of calibrations with monoenergetic neutrons in the neutron energy range from 2 to about 70 MeV the response of Makrofol is now 130 tracks.cm-1.mSv-1 within ± 30%. The linearity of detector response has been checked. The increase of the track density due to the neutron component of the natural background radiation at ground level has been measured during 1.5 y. Additional calibrations were performed in broad neutron beams at the PSI and CERN. The detector is suitable for monitoring the long-term occupational exposure at high energy particle accelerators and the exposure of the aircrews with a lower limit of detection 0.2 mSv per year. Polycarbonate is the only neutron detector which is insensitive to the high energy proton component of cosmic radiation. (author)

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

    International Nuclear Information System (INIS)

    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)

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

    Energy Technology Data Exchange (ETDEWEB)

    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)

  16. Role of C-arm cone-beam CT in chemoembolization for hepatocellular carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyo Cheol [Dept. of Radiology, Seoul National University College of Medicine, Institute of Radiation Medicine, Seoul (Korea, Republic of)

    2015-02-15

    With the advent of C-arm cone-beam computed tomography (CBCT), minimally-invasive procedures in the angiography suite made a new leap beyond the limitations of 2-dimensional (D) angiography alone. C-arm CBCT can help interventional radiologists in several ways with the treatment of hepatocellular carcinoma (HCC); visualization of small tumors and tumor-feeding arteries, identification of occult lesion and 3D configuration of tortuous hepatic arteries, assurance of completeness of chemoembolization, suggestion of presence of extrahepatic collateral arteries supplying HCCs, and prevention of nontarget embolization. With more improvements in the technology, C-arm CBCT may be essential in all kinds of interventional procedures in the near future.

  17. Single-layer and dual-layer contrast-enhanced mammography using amorphous selenium flat panel detectors

    Science.gov (United States)

    Allec, N.; Abbaszadeh, S.; Karim, K. S.

    2011-09-01

    The accumulation of injected contrast agents allows the image enhancement of lesions through the use of contrast-enhanced mammography. In this technique, the combination of two acquired images is used to create an enhanced image. There exist several methods to acquire the images to be combined, which include dual energy subtraction using a single detection layer that suffers from motion artifacts due to patient motion between image acquisition. To mitigate motion artifacts, a detector composed of two layers may be used to simultaneously acquire the low and high energy images. In this work, we evaluate both of these methods using amorphous selenium as the detection material to find the system parameters (tube voltage, filtration, photoconductor thickness and relative intensity ratio) leading to the optimal performance. We then compare the performance of the two detectors under the variation of contrast agent concentration, tumor size and dose. The detectability was found to be most comparable at the lower end of the evaluated factors. The single-layer detector not only led to better contrast, due to its greater spectral separation capabilities, but also had lower quantum noise. The single-layer detector was found to have a greater detectability by a factor of 2.4 for a 2.5 mm radius tumor having a contrast agent concentration of 1.5 mg ml-1 in a 4.5 cm thick 50% glandular breast. The inclusion of motion artifacts in the comparison is part of ongoing research efforts.

  18. Single-layer and dual-layer contrast-enhanced mammography using amorphous selenium flat panel detectors

    International Nuclear Information System (INIS)

    The accumulation of injected contrast agents allows the image enhancement of lesions through the use of contrast-enhanced mammography. In this technique, the combination of two acquired images is used to create an enhanced image. There exist several methods to acquire the images to be combined, which include dual energy subtraction using a single detection layer that suffers from motion artifacts due to patient motion between image acquisition. To mitigate motion artifacts, a detector composed of two layers may be used to simultaneously acquire the low and high energy images. In this work, we evaluate both of these methods using amorphous selenium as the detection material to find the system parameters (tube voltage, filtration, photoconductor thickness and relative intensity ratio) leading to the optimal performance. We then compare the performance of the two detectors under the variation of contrast agent concentration, tumor size and dose. The detectability was found to be most comparable at the lower end of the evaluated factors. The single-layer detector not only led to better contrast, due to its greater spectral separation capabilities, but also had lower quantum noise. The single-layer detector was found to have a greater detectability by a factor of 2.4 for a 2.5 mm radius tumor having a contrast agent concentration of 1.5 mg ml-1 in a 4.5 cm thick 50% glandular breast. The inclusion of motion artifacts in the comparison is part of ongoing research efforts.

  19. Single-layer and dual-layer contrast-enhanced mammography using amorphous selenium flat panel detectors

    Energy Technology Data Exchange (ETDEWEB)

    Allec, N; Abbaszadeh, S; Karim, K S, E-mail: nallec@uwaterloo.ca [Department of Electrical and Computer Engineering, University of Waterloo, 200 University Avenue West, Waterloo N2L 3G1 (Canada)

    2011-09-21

    The accumulation of injected contrast agents allows the image enhancement of lesions through the use of contrast-enhanced mammography. In this technique, the combination of two acquired images is used to create an enhanced image. There exist several methods to acquire the images to be combined, which include dual energy subtraction using a single detection layer that suffers from motion artifacts due to patient motion between image acquisition. To mitigate motion artifacts, a detector composed of two layers may be used to simultaneously acquire the low and high energy images. In this work, we evaluate both of these methods using amorphous selenium as the detection material to find the system parameters (tube voltage, filtration, photoconductor thickness and relative intensity ratio) leading to the optimal performance. We then compare the performance of the two detectors under the variation of contrast agent concentration, tumor size and dose. The detectability was found to be most comparable at the lower end of the evaluated factors. The single-layer detector not only led to better contrast, due to its greater spectral separation capabilities, but also had lower quantum noise. The single-layer detector was found to have a greater detectability by a factor of 2.4 for a 2.5 mm radius tumor having a contrast agent concentration of 1.5 mg ml{sup -1} in a 4.5 cm thick 50% glandular breast. The inclusion of motion artifacts in the comparison is part of ongoing research efforts.

  20. Virtual Reality Aided Positioning of Mobile C-Arms for Image-Guided Surgery

    OpenAIRE

    Zhenzhou Shao; Yong Guan; Jindong Tan

    2014-01-01

    For the image-guided surgery, the positioning of mobile C-arms is a key technique to take X-ray images in a desired pose for the confirmation of current surgical outcome. Unfortunately, surgeons and patient often suffer the radiation exposure due to the repeated imaging when the X-ray image is of poor quality or not captured at a good projection view. In this paper, a virtual reality (VR) aided positioning method for the mobile C-arm is proposed by the alignment of 3D surface model of region ...

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

    OpenAIRE

    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...

  2. Flat panel X-ray detector with reduced internal scattering for improved attenuation accuracy and dynamic range

    Science.gov (United States)

    Smith, Peter D.; Claytor, Thomas N.; Berry, Phillip C.; Hills, Charles R.

    2010-10-12

    An x-ray detector is disclosed that has had all unnecessary material removed from the x-ray beam path, and all of the remaining material in the beam path made as light and as low in atomic number as possible. The resulting detector is essentially transparent to x-rays and, thus, has greatly reduced internal scatter. The result of this is that x-ray attenuation data measured for the object under examination are much more accurate and have an increased dynamic range. The benefits of this improvement are that beam hardening corrections can be made accurately, that computed tomography reconstructions can be used for quantitative determination of material properties including density and atomic number, and that lower exposures may be possible as a result of the increased dynamic range.

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

    International Nuclear Information System (INIS)

    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. SU-D-204-05: Quantitative Comparison of a High Resolution Micro-Angiographic Fluoroscopic (MAF) Detector with a Standard Flat Panel Detector (FPD) Using the New Metric of Generalized Measured Relative Object Detectability (GM-ROD)

    Energy Technology Data Exchange (ETDEWEB)

    Russ, M; Ionita, C; Bednarek, D; Rudin, S [Toshiba Stroke and Vascular Research Center, University at Buffalo (SUNY), Buffalo, NY (United States)

    2015-06-15

    Purpose: In endovascular image-guided neuro-interventions, visualization of fine detail is paramount. For example, the ability of the interventionist to visualize the stent struts depends heavily on the x-ray imaging detector performance. Methods: A study to examine the relative performance of the high resolution MAF-CMOS (pixel size 75µm, Nyquist frequency 6.6 cycles/mm) and a standard Flat Panel Detector (pixel size 194µm, Nyquist frequency 2.5 cycles/mm) detectors in imaging a neuro stent was done using the Generalized Measured Relative Object Detectability (GM-ROD) metric. Low quantum noise images of a deployed stent were obtained by averaging 95 frames obtained by both detectors without changing other exposure or geometric parameters. The square of the Fourier transform of each image is taken and divided by the generalized normalized noise power spectrum to give an effective measured task-specific signal-to-noise ratio. This expression is then integrated from 0 to each of the detector’s Nyquist frequencies, and the GM-ROD value is determined by taking a ratio of the integrals for the MAF-CMOS to that of the FPD. The lower bound of integration can be varied to emphasize high frequencies in the detector comparisons. Results: The MAF-CMOS detector exhibits vastly superior performance over the FPD when integrating over all frequencies, yielding a GM-ROD value of 63.1. The lower bound of integration was stepped up in increments of 0.5 cycles/mm for higher frequency comparisons. As the lower bound increased, the GM-ROD value was augmented, reflecting the superior performance of the MAF-CMOS in the high frequency regime. Conclusion: GM-ROD is a versatile metric that can provide quantitative detector and task dependent comparisons that can be used as a basis for detector selection. Supported by NIH Grant: 2R01EB002873 and an equipment grant from Toshiba Medical Systems Corporation.

  5. SU-D-204-05: Quantitative Comparison of a High Resolution Micro-Angiographic Fluoroscopic (MAF) Detector with a Standard Flat Panel Detector (FPD) Using the New Metric of Generalized Measured Relative Object Detectability (GM-ROD)

    International Nuclear Information System (INIS)

    Purpose: In endovascular image-guided neuro-interventions, visualization of fine detail is paramount. For example, the ability of the interventionist to visualize the stent struts depends heavily on the x-ray imaging detector performance. Methods: A study to examine the relative performance of the high resolution MAF-CMOS (pixel size 75µm, Nyquist frequency 6.6 cycles/mm) and a standard Flat Panel Detector (pixel size 194µm, Nyquist frequency 2.5 cycles/mm) detectors in imaging a neuro stent was done using the Generalized Measured Relative Object Detectability (GM-ROD) metric. Low quantum noise images of a deployed stent were obtained by averaging 95 frames obtained by both detectors without changing other exposure or geometric parameters. The square of the Fourier transform of each image is taken and divided by the generalized normalized noise power spectrum to give an effective measured task-specific signal-to-noise ratio. This expression is then integrated from 0 to each of the detector’s Nyquist frequencies, and the GM-ROD value is determined by taking a ratio of the integrals for the MAF-CMOS to that of the FPD. The lower bound of integration can be varied to emphasize high frequencies in the detector comparisons. Results: The MAF-CMOS detector exhibits vastly superior performance over the FPD when integrating over all frequencies, yielding a GM-ROD value of 63.1. The lower bound of integration was stepped up in increments of 0.5 cycles/mm for higher frequency comparisons. As the lower bound increased, the GM-ROD value was augmented, reflecting the superior performance of the MAF-CMOS in the high frequency regime. Conclusion: GM-ROD is a versatile metric that can provide quantitative detector and task dependent comparisons that can be used as a basis for detector selection. Supported by NIH Grant: 2R01EB002873 and an equipment grant from Toshiba Medical Systems Corporation

  6. C-arm technique using distance driven method for nephrolithiasis and kidney stones detection

    Science.gov (United States)

    Malalla, Nuhad; Sun, Pengfei; Chen, Ying; Lipkin, Michael E.; Preminger, Glenn M.; Qin, Jun

    2016-04-01

    Distance driven represents a state of art method that used for reconstruction for x-ray techniques. C-arm tomography is an x-ray imaging technique that provides three dimensional information of the object by moving the C-shaped gantry around the patient. With limited view angle, C-arm system was investigated to generate volumetric data of the object with low radiation dosage and examination time. This paper is a new simulation study with two reconstruction methods based on distance driven including: simultaneous algebraic reconstruction technique (SART) and Maximum Likelihood expectation maximization (MLEM). Distance driven is an efficient method that has low computation cost and free artifacts compared with other methods such as ray driven and pixel driven methods. Projection images of spherical objects were simulated with a virtual C-arm system with a total view angle of 40 degrees. Results show the ability of limited angle C-arm technique to generate three dimensional images with distance driven reconstruction.

  7. Whole body dual X-ray absorptiometry for bone mineral density and body composition using a flat panel detector

    International Nuclear Information System (INIS)

    Whole-body dual-energy X-ray absorptiometry (DXA) systems are used for the determination of bone mineral density (BMD) but also for body composition estimates (lean mass and fat mass). The calculation is based on the difference in attenuation of body tissues for a low-energy of about 50 KeV and a high-energy of about 80-100 KeV. The measurement of dual-energy projections allows first to compute to the body composition in the non-bone area, and then to extrapolate the fat / lean ratio of soft tissue into the bone area in order to compute the BMD. Since detectors have limited area, a whole body examination requires a scan of the patient and a reconstruction process in order to build up a large field image from smaller radiographs. This reconstruction process must keep the quantitative value of the radiographs, and avoid any distortion which could be a consequence of the conic acquisition geometry. The cone angle is low (6 at maximum) and the large overlap between radiographs helps to reconstruct an image equivalent with a parallel-beam geometry. Scatter is corrected from the radiographs before reconstruction, as described in a previous paper ('Dual-energy X-rays absorptiometry using a 2D digital radiography detector. Application to bone densitometry', SPIE Medical Imaging 2001, Medical Physics). We have developed an original reconstruction method dedicated to whole-body examinations which will be described. Thanks to the quasi-radiologic quality of the detector, reconstructed images are of very good quality and this makes the measurement of BMD and fat / lean masses easier. (author)

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

    Czech Academy of Sciences Publication Activity Database

    Vavřík, Daniel; Fauler, A.; Fiederle, M.; Jandejsek, Ivan; Jakůbek, J.; Tureček, D.; Zwerger, A.

    2013-01-01

    Roč. 8, April (2013), C04009. ISSN 1748-0221. [International Workshop on Radiation Imaging Detector s /14./. Figueira da Foz, Coimbra, 01.07.2012-05.07.2012] R&D Projects: GA ČR(CZ) GA103/09/2101 Institutional support: RVO:68378297 Keywords : X-ray digital radiography * fracture mechanics * crack path * X-ray defectoscopy Subject RIV: JM - Building Engineering Impact factor: 1.526, year: 2013 http://iopscience.iop.org/1748-0221/8/04/C04009/

  9. Measurement of the electrical properties of a polycrystalline cadmium telluride for direct conversion flat panel x-ray detector

    International Nuclear Information System (INIS)

    Cadmium telluride (CdTe) is one of the best candidate direct conversion material for medical X-ray application because it satisfies the requirements of direct conversion x-ray material such as high atomic absorption, density, bandgap energy, work fuction, and resistivity. With such properties, single crystal CdTe exhibits high quantum efficiency and charge collection efficiency. However, for the development of low-cost large area detector, the study of the improvement of polycrystalline CdTe property is desirable. In this study, in order to improve the properties of polycrystalline CdTe, we produced polycrystalline CdTe with different kinds of raw materials, high purity Cd and Te powder compounds and bulk CdTe compound synthesized from single crystal CdTe. The electric properties including resistivity, x-ray sensitivity, and charge transport properties were investigated. As a result, polycrystalline CdTe exhibited simular level of resistivity and x-ray sensitivity to single crystal CdTe. The carrier transport properties of polycrystalline CdTe showed poorer properties than those of single crystal CdTe due to significant charge trapping. However, the polycrystalline CdTe fabricated with bulk CdTe compound synthesized from single crystal CdTe showed better charge transport properties than the polycrystalline CdTe fabricated with CdTe powder compounds. This is suitable for diagnostic x-ray detectors, especially for digital fluoroscopy

  10. 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

    Energy Technology Data Exchange (ETDEWEB)

    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.)

  11. 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

    International Nuclear Information System (INIS)

    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.)

  12. A comparison of entrance skin dose delivered by clinical angiographic c-arms using the real-time dosimeter: the MOSkin.

    Science.gov (United States)

    Thorpe, Nathan Kenneth; Cutajar, Dean; Lian, Cheryl; Pitney, Mark; Friedman, Daniel; Perevertaylo, Vladimir; Rosenfeld, Anatoly

    2016-06-01

    Coronary angiography is a procedure used in the diagnosis and intervention of coronary heart disease. The procedure is often considered one of the highest dose diagnostic procedures in clinical use. Despite this, there is minimal use of dosimeters within angiographic catheterisation laboratories due to challenges resulting from their implementation. The aim of this study was to compare entrance dose delivery across locally commissioned c-arms to assess the need for real-time dosimetry solutions during angiographic procedures. The secondary aim of this study was to establish a calibration method for the MOSkin dosimeter that accurately produces entrance dose values from the clinically sampled beam qualities and energies. The MOSkin is a real-time dosimeter used to measure the skin dose delivered by external radiation beams. The suitability of the MOSkin for measurements in the angiographic catheterisation laboratory was assessed. Measurements were performed using a 30 × 30 × 30 cm(3) PMMA phantom positioned at the rotational isocenter of the c-arm gantry. The MOSkin calibration factor was established through comparison of the MOSkin response to EBT2 film response. Irradiation of the dosimeters was performed using several clinical beam qualities ranging in energy from 70 to 105 kVp. A total of four different interventional c-arm machines were surveyed and compared using the MOSkin dosimeter. The phantom was irradiated from a normal angle of incidence using clinically relevant protocols, field sizes and source to image detector distance values. The MOSkin was observed to be radiotranslucent to the c-arm beam in all clinical environments. The MOSkin response was reproducible to within 2 % of the average value across repeated measurements for each beam setting. There were large variations in entrance dose delivery to the phantom between the different c-arm machines with the highest observed cine-acquisition entrance dose rate measuring 326 % higher than the

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

    Energy Technology Data Exchange (ETDEWEB)

    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.)

  14. A Fast, Accurate and Easy to Implement Method for Pose Recognition of an Intramedullary Nail using a Tracked C-arm

    Science.gov (United States)

    Esfandiari, H.; Amiri, S.; Lichti, D. D.; Anglin, C.

    2014-06-01

    A C-arm is a mobile X-ray device that is frequently used during orthopaedic surgeries. It consists of a semi-circular, arc-shaped arm that holds an X-ray transmitter at one end and an X-ray detector at the other. Intramedullary nail (IM nail) fixation is a popular orthopaedic surgery in which a metallic rod is placed into the patient's fractured bone (femur or tibia) and fixed using metal screws. The main challenge of IM-nail fixation surgery is to achieve the X-ray shot in which the distal holes of the IM nail appear as circles (desired view) so that the surgeon can easily insert the screws. Although C-arm X-ray devices are routinely used in IM-nail fixation surgeries, the surgeons or radiation technologists (rad-techs) usually use it in a trial-and-error manner. This method raises both radiation exposure and surgery time. In this study, we have designed and developed an IM-nail distal locking navigation technique that leads to more accurate and faster screw placement with a lower radiation dose and a minimum number of added steps to the operation to make it more accepted within the orthopaedic community. The specific purpose of this study was to develop and validate an automated technique for identifying the current pose of the IM nail relative to the C-arm. An accuracy assessment was performed to test the reliability of the navigation results. Translational accuracy was demonstrated to be better than 1 mm, roll and pitch rotations better than 2° and yaw rotational accuracy better than 2-5° depending on the separate angle. Computation time was less than 3.5 seconds.

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

    International Nuclear Information System (INIS)

    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.)

  16. Radiation dose in cerebral angiography and flat detector CT applications in neuroradiology; Strahlendosis bei zerebraler Angiographie und Flachdetektor-CT-Applikationen in der Neuroradiologie

    Energy Technology Data Exchange (ETDEWEB)

    Struffert, T.; Lang, S.; Doerfler, A. [Universitaetsklinikum Erlangen, Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Abteilung fuer Neuroradiologie, Erlangen (Germany); Scholz, R. [Siemens Healthcare GmbH, Forchheim (Germany); Hauer, M. [Klinikum Nuernberg Sued, Institut fuer Radiologie und Neuroradiologie, Nuernberg (Germany)

    2015-08-15

    Flat detectors (FD) have completely replaced image intensifiers in angiography. Due to this development not only the image quality of 2D digital subtraction angiography series (2-D-DSA) could be improved but also the acquisition of computed tomography (CT)-like cross-sectional images (FD-CT) within the angio suite became feasible. These techniques are now being used in daily clinical routine. Only little information about effective doses of these applications to patients has been published in the literature. We describe the effective patient dose of current applications in the field of angiography and demonstrate strategies to minimize the dose to the patient. In addition, we compare FD-CT applications to standard multislice CT applications. (orig.) [German] Flachdetektoren haben Bildverstaerker in der Angiographie vollstaendig abgeloest. Mit dieser Entwicklung verbesserte sich nicht nur die Bildqualitaet subtrahierter 2-D-Angiographieserien (2-D-DSA), sondern auch die Akquisition CT-aehnlicher Schnittbilder (FD-CT) mit unterschiedlichen Indikationen wurde moeglich. Diese Techniken werden nun in der taeglichen klinischen Routine eingesetzt. Angaben zur effektiven Patientendosis dieser Applikationen sind bis jetzt in der Literatur nur wenige publiziert worden. Wir beschreiben die effektive Patientendosis aktueller Anwendungen im Bereich der Angiographie und zeigen Strategien zur Minimierung der Dosis fuer den Patienten auf. Zudem vergleichen wir FD-CT-Applikationen mit Standard-Multislice-CT-Anwendungen. (orig.)

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

    International Nuclear Information System (INIS)

    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)

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

    International Nuclear Information System (INIS)

    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 operator radiation exposure between C-arm and O-arm fluoroscopy for orthopaedic surgery

    International Nuclear Information System (INIS)

    The O-arm system has recently been introduced and has the capability of combined two-dimensional (2-D) fluoroscopy imaging and three-dimensional computed tomography imaging. In this study, an orthopaedic surgical procedure using C-arm and O-arm systems in their 2-D fluoroscopy modes was simulated and the radiation doses to susceptible organs to which operators can be exposed were investigated. The experiments were performed in four configurations of the location of the X-ray source and detector. Shielding effects on the thyroid surface and the direct exposure delivered to the surgeon's hands were also compared. The results obtained show that the O-arm delivered higher doses to the sensitive organs of the operator in all configurations. The thyroid shield cut-off 89 % of the dose in the postero-anterior configuration of both imaging systems. Thus, the operators need to pay more attention to managing radiation exposure, especially when using the O-arm system. (authors)

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

    International Nuclear Information System (INIS)

    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

  1. C-arm CT for histomorphometric evaluation of lumbar spine trabecular microarchitecture: a study on anorexia nervosa patients.

    Science.gov (United States)

    Phan, C M; Khalilzadeh, O; Dinkel, J; Wang, I S; Bredella, M A; Misra, M; Miller, K K; Klibanski, A; Gupta, R

    2013-07-01

    Bone histomorphometry measurements require high spatial resolution that may not be feasible using multidetector CT (MDCT). This study evaluated the trabecular microarchitecture of lumbar spine using MDCT and C-arm CT in a series of young adult patients with anorexia nervosa (AN). 11 young females with AN underwent MDCT (anisotropic resolution with a slice thickness of ~626 μm) and C-arm CT (isotropic resolution of ~200 µm). Standard histomorphometric parameters the of L1 vertebral body, namely the apparent trabecular bone volume fraction (BV/TV), trabecular thickness (TbTh), trabecular number (TbN) and trabecular separation (TbSp), were analysed using MicroView software (GE Healthcare, Piscataway, NJ). Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry. Trabecular parameters derived from MDCT and C-arm CT were compared, and their association with BMD parameters was evaluated. Histomorphometric parameters derived from C-arm CT, namely TbTh, TbN and TbSp, were significantly different from the corresponding MDCT parameters. There were no significant correlations between C-arm CT-derived parameters and the corresponding MDCT-derived parameters. C-arm CT-derived parameters were significantly (p<0.001) correlated with anteroposterior L1 spine BMD and Z-scores: TbTh (r=0.723, r=0.744, respectively), TbN (r=-0.720, r=-0.712, respectively) and TbSp (r=0.656, r=0.648, respectively). BV/TV, derived from C-arm CT, was significantly associated with body mass index (r=0.636) and ideal body weight (r=0.730) (p<0.05). These associations were not present in MDCT-derived parameters. This study suggests that the spatial resolution offered by C-arm CT more accurately captures the histomorphometric parameters of trabecular morphology than MDCT in patients with AN. PMID:23640801

  2. Soft-tissue imaging with C-arm cone-beam CT using statistical reconstruction

    Science.gov (United States)

    Wang, Adam S.; Webster Stayman, J.; Otake, Yoshito; Kleinszig, Gerhard; Vogt, Sebastian; Gallia, Gary L.; Khanna, A. Jay; Siewerdsen, Jeffrey H.

    2014-02-01

    The potential for statistical image reconstruction methods such as penalized-likelihood (PL) to improve C-arm cone-beam CT (CBCT) soft-tissue visualization for intraoperative imaging over conventional filtered backprojection (FBP) is assessed in this work by making a fair comparison in relation to soft-tissue performance. A prototype mobile C-arm was used to scan anthropomorphic head and abdomen phantoms as well as a cadaveric torso at doses substantially lower than typical values in diagnostic CT, and the effects of dose reduction via tube current reduction and sparse sampling were also compared. Matched spatial resolution between PL and FBP was determined by the edge spread function of low-contrast (˜40-80 HU) spheres in the phantoms, which were representative of soft-tissue imaging tasks. PL using the non-quadratic Huber penalty was found to substantially reduce noise relative to FBP, especially at lower spatial resolution where PL provides a contrast-to-noise ratio increase up to 1.4-2.2× over FBP at 50% dose reduction across all objects. Comparison of sampling strategies indicates that soft-tissue imaging benefits from fully sampled acquisitions at dose above ˜1.7 mGy and benefits from 50% sparsity at dose below ˜1.0 mGy. Therefore, an appropriate sampling strategy along with the improved low-contrast visualization offered by statistical reconstruction demonstrates the potential for extending intraoperative C-arm CBCT to applications in soft-tissue interventions in neurosurgery as well as thoracic and abdominal surgeries by overcoming conventional tradeoffs in noise, spatial resolution, and dose.

  3. 3D ablation catheter localisation using individual C-arm x-ray projections

    Science.gov (United States)

    Haase, C.; Schäfer, D.; Dössel, O.; Grass, M.

    2014-11-01

    Cardiac ablation procedures during electrophysiology interventions are performed under x-ray guidance with a C-arm imaging system. Some procedures require catheter navigation in complex anatomies like the left atrium. Navigation aids like 3D road maps and external tracking systems may be used to facilitate catheter navigation. As an alternative to external tracking a fully automatic method is presented here that enables the calculation of the 3D location of the ablation catheter from individual 2D x-ray projections. The method registers a high resolution, deformable 3D attenuation model of the catheter to a 2D x-ray projection. The 3D localization is based on the divergent beam projection of the catheter. On an individual projection, the catheter tip is detected in 2D by image filtering and a template matching method. The deformable 3D catheter model is adapted using the projection geometry provided by the C-arm system and 2D similarity measures for an accurate 2D/3D registration. Prior to the tracking and registration procedure, the deformable 3D attenuation model is automatically extracted from a separate 3D cone beam CT reconstruction of the device. The method can hence be applied to various cardiac ablation catheters. In a simulation study of a virtual ablation procedure with realistic background, noise, scatter and motion blur an average 3D registration accuracy of 3.8 mm is reached for the catheter tip. In this study four different types of ablation catheters were used. Experiments using measured C-arm fluoroscopy projections of a catheter in a RSD phantom deliver an average 3D accuracy of 4.5 mm.

  4. Interventional heart wall motion analysis with cardiac C-arm CT systems

    International Nuclear Information System (INIS)

    Today, quantitative analysis of three-dimensional (3D) dynamics of the left ventricle (LV) cannot be performed directly in the catheter lab using a current angiographic C-arm system, which is the workhorse imaging modality for cardiac interventions. Therefore, myocardial wall analysis is completely based on the 2D angiographic images or pre-interventional 3D/4D imaging. In this paper, we present a complete framework to study the ventricular wall motion in 4D (3D+t) directly in the catheter lab. From the acquired 2D projection images, a dynamic 3D surface model of the LV is generated, which is then used to detect ventricular dyssynchrony. Different quantitative features to evaluate LV dynamics known from other modalities (ultrasound, magnetic resonance imaging) are transferred to the C-arm CT data. We use the ejection fraction, the systolic dyssynchrony index a 3D fractional shortening and the phase to maximal contraction (ϕi, max) to determine an indicator of LV dyssynchrony and to discriminate regionally pathological from normal myocardium. The proposed analysis tool was evaluated on simulated phantom LV data with and without pathological wall dysfunctions. The LV data used is publicly available online at https://conrad.stanford.edu/data/heart. In addition, the presented framework was tested on eight clinical patient data sets. The first clinical results demonstrate promising performance of the proposed analysis tool and encourage the application of the presented framework to a larger study in clinical practice. (paper)

  5. Interventional heart wall motion analysis with cardiac C-arm CT systems

    Science.gov (United States)

    Müller, Kerstin; Maier, Andreas K.; Zheng, Yefeng; Wang, Yang; Lauritsch, Günter; Schwemmer, Chris; Rohkohl, Christopher; Hornegger, Joachim; Fahrig, Rebecca

    2014-05-01

    Today, quantitative analysis of three-dimensional (3D) dynamics of the left ventricle (LV) cannot be performed directly in the catheter lab using a current angiographic C-arm system, which is the workhorse imaging modality for cardiac interventions. Therefore, myocardial wall analysis is completely based on the 2D angiographic images or pre-interventional 3D/4D imaging. In this paper, we present a complete framework to study the ventricular wall motion in 4D (3D+t) directly in the catheter lab. From the acquired 2D projection images, a dynamic 3D surface model of the LV is generated, which is then used to detect ventricular dyssynchrony. Different quantitative features to evaluate LV dynamics known from other modalities (ultrasound, magnetic resonance imaging) are transferred to the C-arm CT data. We use the ejection fraction, the systolic dyssynchrony index a 3D fractional shortening and the phase to maximal contraction (ϕi, max) to determine an indicator of LV dyssynchrony and to discriminate regionally pathological from normal myocardium. The proposed analysis tool was evaluated on simulated phantom LV data with and without pathological wall dysfunctions. The LV data used is publicly available online at https://conrad.stanford.edu/data/heart. In addition, the presented framework was tested on eight clinical patient data sets. The first clinical results demonstrate promising performance of the proposed analysis tool and encourage the application of the presented framework to a larger study in clinical practice.

  6. Radiation protection for an intraoperative X-ray source compared to C-arm fluoroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, Frank; Clausen, Sven; Jahnke, Anika; Steil, Volker; Wenz, Frederik [Heidelberg Univ., University Medical Center Mannheim (Germany). Dept. of Radiation Oncology; Bludau, Frederic; Obertacke, Udo [Heidelberg Univ., University Medical Center Mannheim (Germany). Dept. of Trauma Surgery; Suetterlin, Marc [Heidelberg Univ., University Medical Center Mannheim (Germany). Dept. of Obstetrics and Gynaecology

    2014-10-01

    Background: Intraoperative radiotherapy (IORT) using the INTRABEAM {sup registered} system promises a flexible use regarding radiation protection compared to other approaches such as electron treatment or HDR brachytherapy with {sup 192}Ir or {sup 60}Co. In this study we compared dose rate measurements of breast- and Kypho-IORT with C-arm fluoroscopy which is needed to estimate radiation protection areas. Materials and Methods: C-arm fluoroscopy, breast- and Kypho-IORTs were performed using phantoms (silicon breast or bucket of water). Dose rates were measured at the phantom's surface, at 30 cm, 100 cm and 200 cm distance. Those measurements were confirmed during 10 Kypho-IORT and 10 breast-IORT patient treatments. Results: The measured dose rates were in the same magnitude for all three paradigms and ranges from 20 μSv/h during a simulated breast-IORT at two meter distance up to 64 mSv/h directly at the surface of a simulated Kypho-IORT. Those measurements result in a circle of controlled area (yearly doses > 6 mSv) for each paradigm of about 4 m ± 2 m. Discussion/Conclusions: All three paradigms show comparable dose rates which implies that the radiation protection is straight forward and confirms the flexible use of the INTRABEAM {sup registered} system. (orig.)

  7. Quality assurance programme applied to mobile C-arm fluoroscopy systems

    International Nuclear Information System (INIS)

    The importance of quality assurance (QA) of X-ray equipment in diagnostic imaging departments is well recognised. However, practically no attention has been paid in the literature to the application of QA programmes to mobile C-arm fluoroscopy systems. This equipment is sometimes omitted from these programmes because it is often 'off-site' from the main radiological facility and suitable QA protocols are unavailable. The need for QA can be substantiated by the fact that these systems are finding greater clinical use in orthopaedic, vascular and cardiac applications. Hence, there is a growing awareness among users for the need of good image quality and low patient radiation dose. In view of this, the objective of this study was to review the existing literature, design a suitable QA protocol for this equipment and use it to survey 10 C-arms in clinical use. The protocol was designed to address mechanical and electrical safety in addition to radiation safety and image quality. Results indicate substantial performance differences between systems with significant variations in input air kerma rate to the image receptor. The authors believe that such a protocol is necessary with a view to establishing optimal performance levels and assist in the development of suitable 'write-off' criteria for such systems. (orig.)

  8. Radiation protection for an intraoperative X-ray source compared to C-arm fluoroscopy

    International Nuclear Information System (INIS)

    Background: Intraoperative radiotherapy (IORT) using the INTRABEAM registered system promises a flexible use regarding radiation protection compared to other approaches such as electron treatment or HDR brachytherapy with 192Ir or 60Co. In this study we compared dose rate measurements of breast- and Kypho-IORT with C-arm fluoroscopy which is needed to estimate radiation protection areas. Materials and Methods: C-arm fluoroscopy, breast- and Kypho-IORTs were performed using phantoms (silicon breast or bucket of water). Dose rates were measured at the phantom's surface, at 30 cm, 100 cm and 200 cm distance. Those measurements were confirmed during 10 Kypho-IORT and 10 breast-IORT patient treatments. Results: The measured dose rates were in the same magnitude for all three paradigms and ranges from 20 μSv/h during a simulated breast-IORT at two meter distance up to 64 mSv/h directly at the surface of a simulated Kypho-IORT. Those measurements result in a circle of controlled area (yearly doses > 6 mSv) for each paradigm of about 4 m ± 2 m. Discussion/Conclusions: All three paradigms show comparable dose rates which implies that the radiation protection is straight forward and confirms the flexible use of the INTRABEAM registered system. (orig.)

  9. The rotate-plus-shift C-arm trajectory: Complete CT data with less than 180{\\deg} rotation

    CERN Document Server

    Ritschl, Ludwig; Kachelrieß, Marc

    2014-01-01

    In the last decade C-arm-based cone-beam CT became a widely used modality for intraoperative imaging. Typically a C-arm scan is performed using a circle-like trajectory around a region of interest. Therefor an angular range of at least 180{\\deg} plus fan-angle must be covered to ensure a completely sampled data set. This fact defines some constraints on the geometry and technical specifications of a C-arm system, for example a larger C radius or a smaller C opening respectively. These technical modifications are usually not benificial in terms of handling and usability of the C-arm during classical 2D applications like fluoroscopy. The method proposed in this paper relaxes the constraint of 180{\\deg} plus fan-angle rotation to acquire a complete data set. The proposed C-arm trajectory requires a motorization of the orbital axis of the C and of ideally two orthogonal axis in the C plane. The trajectory consists of three parts: A rotation of the C around a defined iso-center and two translational movements para...

  10. Radiation dose reduction and new image modalities development for interventional C-arm imaging system

    Science.gov (United States)

    Niu, Kai

    Cardiovascular disease and stroke are the leading health problems and causes of death in the US. Due to the minimally invasive nature of the evolution of image guided techniques, interventional radiological procedures are becoming more common and are preferred in treating many cardiovascular diseases and strokes. In addition, with the recent advances in hardware and device technology, the speed and efficacy of interventional treatment has significantly improved. This implies that more image modalities can be developed based on the current C-arm system and patients treated in interventional suites can potentially experience better health outcomes. However, during the treatment patients are irradiated with substantial amounts of ionizing radiation with a high dose rate (digital subtraction angiography (DSA) with 3muGy/frame and 3D cone beam CT image with 0.36muGy/frame for a Siemens Artis Zee biplane system) and/or a long irradiation time (a roadmapping image sequence can be as long as one hour during aneurysm embolization). As a result, the patient entrance dose is extremely high. Despite the fact that the radiation dose is already substantial, image quality is not always satisfactory. By default a temporal average is used in roadmapping images to overcome poor image quality, but this technique can result in motion blurred images. Therefore, reducing radiation dose while maintaining or even improving the image quality is an important area for continued research. This thesis is focused on improving the clinical applications of C-arm cone beam CT systems in two ways: (1) Improve the performance of current image modalities on the C-arm system. (2) Develop new image modalities based on the current system. To be more specific, the objectives are to reduce radiation dose for current modalities (e.g., DSA, fluoroscopy, roadmapping, and cone beam CT) and enable cone beam CT perfusion and time resolved cone beam CT angiography that can be used to diagnose and triage acute

  11. Dose and detectability for a cone-beam C-arm CT system revisited

    International Nuclear Information System (INIS)

    Purpose: The authors had previously published measurements of the detectability of disk-shaped contrast objects in images obtained from a C-arm CT system. A simple approach based on Rose's criterion was used to scale the date, assuming the threshold for the smallest diameter detected should be inversely proportional to (dose)1/2. A more detailed analysis based on recent theoretical modeling of C-arm CT images is presented in this work. Methods: The signal and noise propagations in a C-arm based CT system have been formulated by other authors using cascaded systems analysis. They established a relationship between detectability and the noise equivalent quanta. Based on this model, the authors obtained a relation between x-ray dose and the diameter of the smallest disks detected. A closed form solution was established by assuming no rebinning and no resampling of data, with low additive noise and using a ramp filter. For the case when no such assumptions were made, a numerically calculated solution using previously reported imaging and reconstruction parameters was obtained. The detection probabilities for a range of dose and kVp values had been measured previously. These probabilities were normalized to a single dose of 56.6 mGy using the Rose-criteria-based relation to obtain a universal curve. Normalizations based on the new numerically calculated relationship were compared to the measured results. Results: The theoretical and numerical calculations have similar results and predict the detected diameter size to be inversely proportional to (dose)1/3 and (dose)1/2.8, respectively. The normalized experimental curves and the associated universal plot using the new relation were not significantly different from those obtained using the Rose-criterion-based normalization. Conclusions: From numerical simulations, the authors found that the diameter of detected disks depends inversely on the cube root of the dose. For observer studies for disks larger than 4 mm, the cube

  12. Needle and catheter navigation using electromagnetic tracking for computer-assisted C-arm CT interventions

    Science.gov (United States)

    Nagel, Markus; Hoheisel, Martin; Petzold, Ralf; Kalender, Willi A.; Krause, Ulrich H. W.

    2007-03-01

    Integrated solutions for navigation systems with CT, MR or US systems become more and more popular for medical products. Such solutions improve the medical workflow, reduce hardware, space and costs requirements. The purpose of our project was to develop a new electromagnetic navigation system for interventional radiology which is integrated into C-arm CT systems. The application is focused on minimally invasive percutaneous interventions performed under local anaesthesia. Together with a vacuum-based patient immobilization device and newly developed navigation tools (needles, panels) we developed a safe and fully automatic navigation system. The radiologist can directly start with navigated interventions after loading images without any prior user interaction. The complete system is adapted to the requirements of the radiologist and to the clinical workflow. For evaluation of the navigation system we performed different phantom studies and achieved an average accuracy of better than 2.0 mm.

  13. 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

    International Nuclear Information System (INIS)

    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.)

  14. C-arm CT for histomorphometric evaluation of lumbar spine trabecular microarchitecture: a study on anorexia nervosa patients

    OpenAIRE

    Phan, C M; Khalilzadeh, O; Dinkel, J; Wang, I S; Bredella, M.A.; Misra, M.; Miller, K. K.; Klibanski, A.; Gupta, R.

    2013-01-01

    Bone histomorphometry measurements require high spatial resolution that may not be feasible using multidetector CT (MDCT). This study evaluated the trabecular microarchitecture of lumbar spine using MDCT and C-arm CT in a series of young adult patients with anorexia nervosa (AN). 11 young females with AN underwent MDCT (anisotropic resolution with a slice thickness of ∼626 μm) and C-arm CT (isotropic resolution of ∼200 µm). Standard histomorphometric parameters the of L1 vertebral body, namel...

  15. Use of C-arm CT for improving the hit rate for selective blood sampling from adrenal veins; Einsatz der C-Arm-CT zur Verbesserung der Trefferquote bei selektiver Nebennierenvenen-Blutentnahme

    Energy Technology Data Exchange (ETDEWEB)

    Georgiades, C.; Valdeig, S.; Hong, K. [Johns Hopkins Outpatient Center (JHOC), Russell H. Morgan Department of Radiology and Radiological Science, Division of Vascular and Interventional Radiology, Baltimore (United States); Kharlip, J. [Johns Hopkins Hospital, Abteilung fuer Endokrinologie, Baltimore (United States); Wacker, F.K. [Johns Hopkins Outpatient Center (JHOC), Russell H. Morgan Department of Radiology and Radiological Science, Division of Vascular and Interventional Radiology, Baltimore (United States); Campus Benjamin Franklin, Charite, Universitaetsmedizin Berlin, Klinik und Hochschulambulanz fuer Radiologie und Nuklearmedizin, Berlin (Germany)

    2009-09-15

    Primary hyperaldosteronism is the most common curable cause of hypertension with a prevalence of up to 12% among patients with hypertension. Selective blood sampling from adrenal veins is considered the diagnostic gold standard. However, it is underutilized due to the high technical failure rate. The use of C-arm CT during the sampling procedure can reduce or even eliminate this failure rate. If adrenal vein sampling is augmented by native C-arm CT to check for the correct catheter position, the technical success rate increases substantially. General use of this technique will result in correct diagnosis and treatment for patients with primary hyperaldosteronism. (orig.) [German] Der primaere Hyperaldosteronismus (PHA) ist die am haeufigsten vorkommende heilbare Ursache von Bluthochdruck mit einer Praevalenz bei Hypertonikern bis zu 12%. Die selektive Blutentnahme aus der Nebennierenvene (NNV) gilt als diagnostischer Goldstandard. Sie wird jedoch aufgrund einer hohen Fehlerquote oftmals nicht genutzt. Die Anwendung der C-Arm-CT waehrend der Blutentnahme kann diese Fehlerquote reduzieren bzw. eliminieren. Wird waehrend der Intervention unter Durchleuchtung die C-Arm-CT eingesetzt, um die Katheterlage vor der Blutentnahme zu pruefen, verbessert dies den technischen Erfolg des Verfahrens erheblich. Etabliert sich dieses Verfahren, bedeutet dies eine Verbesserung von Diagnose und Behandlung der Patienten mit primaerem Hyperaldosteronismus. (orig.)

  16. Reinforcing the role of the conventional C-arm - a novel method for simplified distal interlocking

    Directory of Open Access Journals (Sweden)

    Windolf Markus

    2012-01-01

    Full Text Available Abstract Background The common practice for insertion of distal locking screws of intramedullary nails is a freehand technique under fluoroscopic control. The process is technically demanding, time-consuming and afflicted to considerable radiation exposure of the patient and the surgical personnel. A new concept is introduced utilizing information from within conventional radiographic images to help accurately guide the surgeon to place the interlocking bolt into the interlocking hole. The newly developed technique was compared to conventional freehand in an operating room (OR like setting on human cadaveric lower legs in terms of operating time and radiation exposure. Methods The proposed concept (guided freehand, generally based on the freehand gold standard, additionally guides the surgeon by means of visible landmarks projected into the C-arm image. A computer program plans the correct drilling trajectory by processing the lens-shaped hole projections of the interlocking holes from a single image. Holes can be drilled by visually aligning the drill to the planned trajectory. Besides a conventional C-arm, no additional tracking or navigation equipment is required. Ten fresh frozen human below-knee specimens were instrumented with an Expert Tibial Nail (Synthes GmbH, Switzerland. The implants were distally locked by performing the newly proposed technique as well as the conventional freehand technique on each specimen. An orthopedic resident surgeon inserted four distal screws per procedure. Operating time, number of images and radiation time were recorded and statistically compared between interlocking techniques using non-parametric tests. Results A 58% reduction in number of taken images per screw was found for the guided freehand technique (7.4 ± 3.4 (mean ± SD compared to the freehand technique (17.6 ± 10.3 (p p = 0.001. Operating time per screw (from first shot to screw tightened was on average 22% reduced by guided freehand (p = 0

  17. Dose and image quality for a cone-beam C-arm CT system

    International Nuclear Information System (INIS)

    We assess dose and image quality of a state-of-the-art angiographic C-arm system (Axiom Artis dTA, Siemens Medical Solutions, Forchheim, Germany) for three-dimensional neuro-imaging at various dose levels and tube voltages and an associated measurement method. Unlike conventional CT, the beam length covers the entire phantom, hence, the concept of computed tomography dose index (CTDI) is not the metric of choice, and one can revert to conventional dosimetry methods by directly measuring the dose at various points using a small ion chamber. This method allows us to define and compute a new dose metric that is appropriate for a direct comparison with the familiar CTDIW of conventional CT. A perception study involving the CATPHAN 600 indicates that one can expect to see at least the 9 mm inset with 0.5% nominal contrast at the recommended head-scan dose (60 mGy) when using tube voltages ranging from 70 kVp to 125 kVp. When analyzing the impact of tube voltage on image quality at a fixed dose, we found that lower tube voltages gave improved low contrast detectability for small-diameter objects. The relationships between kVp, image noise, dose, and contrast perception are discussed

  18. Acquiring Multiview C-Arm Images to Assist Cardiac Ablation Procedures

    Directory of Open Access Journals (Sweden)

    Pascal Fallavollita

    2010-01-01

    Full Text Available CARTO XP is an electroanatomical cardiac mapping system that provides 3D color-coded maps of the electrical activity of the heart; however it is expensive and it can only use a single costly magnetic catheter for each patient intervention. Our approach consists of integrating fluoroscopic and electrical data from the RF catheters into the same image so as to better guide RF ablation, shorten the duration of this procedure, increase its efficacy, and decrease hospital cost when compared to CARTO XP. We propose a method that relies on multi-view C-arm fluoroscopy image acquisition for (1 the 3D reconstruction of the anatomical structure of interest, (2 the robust temporal tracking of the tip-electrode of a mapping catheter between the diastolic and systolic phases and (3 the 2D/3D registration of color coded isochronal maps directly on the 2D fluoroscopy image that would help the clinician guide the ablation procedure much more effectively. The method has been tested on canine experimental data.

  19. Clinical usefulness of c-arm cone-beam CT inpercutaneous drainage of inaccessible abscess

    Energy Technology Data Exchange (ETDEWEB)

    So, Young Ho; Choi, Young Ho; Woo, Hyun Sik; Moon, Min Hoan; Sung, Chang Kyu [Dept. of Radiology, Seoul Metropolitan Government Seoul National University Boramae Medical Center, Seoul (Korea, Republic of); Hur, Bo Yun [Dept. of Radiology, National Cancer Center, Goyang (Korea, Republic of)

    2015-08-15

    The objective of this study was to evaluate the usefulness of C-arm cone-beam CT (CBCT) in drainage of inaccessible abscesses. To identify the trajectory of the needle or guide wire, CBCT was performed on 21 patients having an inaccessible abscess. CBCT was repeated until proper targeting of the abscess was achieved, before the insertion of a large bore catheter. The etiology, location of the abscess, causes of inaccessibility, radiation dose, technical and clinical success rates of drainage, and any complications confronted, were evaluated. A total of 29 CBCTs were performed for 21 abscesses. Postoperative and non-postoperative abscesses were 9 (42.9%) and 12 (57.1%) in number, respectively. Direct puncture was performed in 18 cases. In 3 cases, the surgical drain or the fistula opening was used as an access route. The causes of inaccessibility were narrow safe window due to adjacent or overlying organs (n = 9), irregularly dispersed abscess (n = 7), deep location with poor sonographic visualization (n = 4), and remote location of the abscess from surgical drain (n = 1). Technical and clinical successes were 95.5% and 100%, respectively. Cumulative air kerma and dose-area product were 21.62 ± 5.41 mGy and 9179.87 ± 2337.70 mGycm2, respectively. There were no procedure related complications. CBCT is a useful technique for identifying the needle and guide wire during drainage of inaccessible abscess.

  20. High-performance C-arm cone-beam CT guidance of thoracic surgery

    Science.gov (United States)

    Schafer, Sebastian; Otake, Yoshito; Uneri, Ali; Mirota, Daniel J.; Nithiananthan, Sajendra; Stayman, J. W.; Zbijewski, Wojciech; Kleinszig, Gerhard; Graumann, Rainer; Sussman, Marc; Siewerdsen, Jeffrey H.

    2012-02-01

    Localizing sub-palpable nodules in minimally invasive video-assisted thoracic surgery (VATS) presents a significant challenge. To overcome inherent problems of preoperative nodule tagging using CT fluoroscopic guidance, an intraoperative C-arm cone-beam CT (CBCT) image-guidance system has been developed for direct localization of subpalpable tumors in the OR, including real-time tracking of surgical tools (including thoracoscope), and video-CBCT registration for augmentation of the thoracoscopic scene. Acquisition protocols for nodule visibility in the inflated and deflated lung were delineated in phantom and animal/cadaver studies. Motion compensated reconstruction was implemented to account for motion induced by the ventilated contralateral lung. Experience in CBCT-guided targeting of simulated lung nodules included phantoms, porcine models, and cadavers. Phantom studies defined low-dose acquisition protocols providing contrast-to-noise ratio sufficient for lung nodule visualization, confirmed in porcine specimens with simulated nodules (3-6mm diameter PE spheres, ~100-150HU contrast, 2.1mGy). Nodule visibility in CBCT of the collapsed lung, with reduced contrast according to air volume retention, was more challenging, but initial studies confirmed visibility using scan protocols at slightly increased dose (~4.6-11.1mGy). Motion compensated reconstruction employing a 4D deformation map in the backprojection process reduced artifacts associated with motion blur. Augmentation of thoracoscopic video with renderings of the target and critical structures (e.g., pulmonary artery) showed geometric accuracy consistent with camera calibration and the tracking system (2.4mm registration error). Initial results suggest a potentially valuable role for CBCT guidance in VATS, improving precision in minimally invasive, lungconserving surgeries, avoid critical structures, obviate the burdens of preoperative localization, and improve patient safety.

  1. Efficient segmentation of 3D fluoroscopic datasets from mobile C-arm

    Science.gov (United States)

    Styner, Martin A.; Talib, Haydar; Singh, Digvijay; Nolte, Lutz-Peter

    2004-05-01

    The emerging mobile fluoroscopic 3D technology linked with a navigation system combines the advantages of CT-based and C-arm-based navigation. The intra-operative, automatic segmentation of 3D fluoroscopy datasets enables the combined visualization of surgical instruments and anatomical structures for enhanced planning, surgical eye-navigation and landmark digitization. We performed a thorough evaluation of several segmentation algorithms using a large set of data from different anatomical regions and man-made phantom objects. The analyzed segmentation methods include automatic thresholding, morphological operations, an adapted region growing method and an implicit 3D geodesic snake method. In regard to computational efficiency, all methods performed within acceptable limits on a standard Desktop PC (30sec-5min). In general, the best results were obtained with datasets from long bones, followed by extremities. The segmentations of spine, pelvis and shoulder datasets were generally of poorer quality. As expected, the threshold-based methods produced the worst results. The combined thresholding and morphological operations methods were considered appropriate for a smaller set of clean images. The region growing method performed generally much better in regard to computational efficiency and segmentation correctness, especially for datasets of joints, and lumbar and cervical spine regions. The less efficient implicit snake method was able to additionally remove wrongly segmented skin tissue regions. This study presents a step towards efficient intra-operative segmentation of 3D fluoroscopy datasets, but there is room for improvement. Next, we plan to study model-based approaches for datasets from the knee and hip joint region, which would be thenceforth applied to all anatomical regions in our continuing development of an ideal segmentation procedure for 3D fluoroscopic images.

  2. Intra-operative dosimetry of trans-rectal ultrasound guided 125I prostate implants using C-arm fluoroscopic images

    Directory of Open Access Journals (Sweden)

    Ravindran Paul

    2006-01-01

    Full Text Available Permanent implantation of radioactive seeds is a viable and effective therapeutic option widely used today for early-stage prostate cancer. The implant technique has improved considerably during the recent years due to the use of image guidance; however, real-time dose distributions would allow potential cold spots to be assessed and additional seeds added. In this study, we investigate the use of a conventional C-arm fluoroscopy unit for image acquisition and evaluation of dose distribution immediately after the implant. The phantom study indicates that it is possible to obtain seed positions within ±2 mm. A pilot study carried out with three patients indicated that it is possible to obtain seed positions and calculate the dose distribution with C-arm fluoroscopy and about 95% of the seeds were reconstructed within ±2 mm. The results could be further improved with better digital imaging.

  3. 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

    International Nuclear Information System (INIS)

    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.)

  4. 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

    Energy Technology Data Exchange (ETDEWEB)

    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.)

  5. C-arm cone-beam CT combined with a new electromagnetic navigation system for guidance of percutaneous needle biopsies. Initial clinical experience

    Energy Technology Data Exchange (ETDEWEB)

    Kickuth, R.; Reichling, C.; Bley, T.; Hahn, D.; Ritter, C. [University Hospital of Wuerzburg (Germany). Inst. of Diagnostic and Interventional Radiology

    2015-07-15

    To evaluate the feasibility and efficacy of C-arm fluoroscopic cone-beam computed tomography (CACT) in combination with a new electromagnetic tracking (EMT) system for needle guidance during percutaneous biopsies. 53 patients were referred for biopsy of thoracic (n = 19) and abdominal (n = 34) lesions. CT-like images of the anatomical region of interest (ROI) were generated using a flat panel-based angiographic system. These images were transmitted to an EMT system. A coaxial puncture needle with a sensor in its tip was connected with the navigation system and tracked into an electromagnetic field created via a field generator. Data generated within this field were merged with the CACT images. On a monitor both the anatomical ROI and needle tip position were displayed to enable precise needle insertion into the target. Through the coaxial needle, biopsy specimens for the histologic evaluation were extracted. Number of representative biopsy samples, number of core biopsies/patient, total procedure time, dose-area product, fluoroscopic time, and complications were recorded. 53 CACT/EMT-guided biopsy procedures were performed, 48 of which (91 %) yielded representative tissue samples. Four core biopsies were obtained from each patient. 40 (75 %) lesions were malignant and 13 (25 %) lesions were benign. The total procedure time was 9 ± 5 min (range, 3 - 23 min), fluoroscopic time was 0.8 ± 0.4 min (range, 0.4 - 2 min). The mean dose-area product (cGy cm{sup 2}) was 7373 (range, 895 - 26 904). The rate of complications (1 pneumothorax, 2 hemoptyses) was 6 %. CACT combined with EMT appears to be a feasible and effective technique for the guidance of percutaneous biopsies with a low rate of therapeutically relevant complications.

  6. C-arm cone-beam CT combined with a new electromagnetic navigation system for guidance of percutaneous needle biopsies. Initial clinical experience

    International Nuclear Information System (INIS)

    To evaluate the feasibility and efficacy of C-arm fluoroscopic cone-beam computed tomography (CACT) in combination with a new electromagnetic tracking (EMT) system for needle guidance during percutaneous biopsies. 53 patients were referred for biopsy of thoracic (n = 19) and abdominal (n = 34) lesions. CT-like images of the anatomical region of interest (ROI) were generated using a flat panel-based angiographic system. These images were transmitted to an EMT system. A coaxial puncture needle with a sensor in its tip was connected with the navigation system and tracked into an electromagnetic field created via a field generator. Data generated within this field were merged with the CACT images. On a monitor both the anatomical ROI and needle tip position were displayed to enable precise needle insertion into the target. Through the coaxial needle, biopsy specimens for the histologic evaluation were extracted. Number of representative biopsy samples, number of core biopsies/patient, total procedure time, dose-area product, fluoroscopic time, and complications were recorded. 53 CACT/EMT-guided biopsy procedures were performed, 48 of which (91 %) yielded representative tissue samples. Four core biopsies were obtained from each patient. 40 (75 %) lesions were malignant and 13 (25 %) lesions were benign. The total procedure time was 9 ± 5 min (range, 3 - 23 min), fluoroscopic time was 0.8 ± 0.4 min (range, 0.4 - 2 min). The mean dose-area product (cGy cm2) was 7373 (range, 895 - 26 904). The rate of complications (1 pneumothorax, 2 hemoptyses) was 6 %. CACT combined with EMT appears to be a feasible and effective technique for the guidance of percutaneous biopsies with a low rate of therapeutically relevant complications.

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

    International Nuclear Information System (INIS)

    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)

  8. C-Arm Cone-Beam CT-Guided Transthoracic Lung Core Needle Biopsy as a Standard Diagnostic Tool

    Science.gov (United States)

    Jaconi, Marta; Pagni, Fabio; Vacirca, Francesco; Leni, Davide; Corso, Rocco; Cortinovis, Diego; Bidoli, Paolo; Bono, Francesca; Cuttin, Maria S.; Valente, Maria G.; Pesci, Alberto; Bedini, Vittorio A.; Leone, Biagio E.

    2015-01-01

    Abstract C-arm cone-beam computed tomography (CT)-guided transthoracic lung core needle biopsy (CNB) is a safe and accurate procedure for the evaluation of patients with pulmonary nodules. This article will focus on the clinical features related to CNB in terms of diagnostic performance and complication rate. Moreover, the concept of categorizing pathological diagnosis into 4 categories, which could be used for clinical management, follow-up, and quality assurance is also introduced. We retrospectively collected data regarding 375 C-arm cone-beam CT-guided CNBs from January 2010 and June 2014. Clinical and radiological variables were evaluated in terms of success or failure rate. Pathological reports were inserted in 4 homogenous groups (nondiagnostic-L1, benign-L2, malignant not otherwise specified-L3, and malignant with specific histotype-L4), defining for each category a hierarchy of suggested actions. The sensitivity, specificity, and positive and negative predictive value and accuracy for patients subjected to CNBs were of 96.8%, 100%, 100%, 100%, and 97.2%, respectively. Roughly 75% of our samples were diagnosed as malignant, with 60% lung adenocarcinoma diagnoses. Molecular analyses were performed on 85 malignant samples to verify applicability of targeted therapy. The rate of “nondiagnostic” samples was 12%. C-arm cone-beam CT-guided transthoracic lung CNB can represent the gold standard for the diagnostic evaluation of pulmonary nodules. A clinical and pathological multidisciplinary evaluation of CNBs was needed in terms of integration of radiological, histological, and oncological data. This approach provided exceptional performances in terms of specificity, positive and negative predictive values; sensitivity in our series was lower compared with other large studies, probably due to the application of strong criteria of adequacy for CNBs (L1 class rate). The satisfactory rate of collected material was evaluated not only in terms of merely diagnostic

  9. Use of C-Arm Cone Beam CT During Hepatic Radioembolization: Protocol Optimization for Extrahepatic Shunting and Parenchymal Enhancement

    International Nuclear Information System (INIS)

    PurposeTo optimize a C-arm computed tomography (CT) protocol for radioembolization (RE), specifically for extrahepatic shunting and parenchymal enhancement.Materials and MethodsA prospective development study was performed per IDEAL recommendations. A literature-based protocol was applied in patients with unresectable and chemorefractory liver malignancies undergoing an angiography before radioembolization. Contrast and scan settings were adjusted stepwise and repeatedly reviewed in a consensus meeting. Afterwards, two independent raters analyzed all scans. A third rater evaluated the SPECT/CT scans as a reference standard for extrahepatic shunting and lack of target segment perfusion.ResultsFifty scans were obtained in 29 procedures. The first protocol, using a 6 s delay and 10 s scan, showed insufficient parenchymal enhancement. In the second protocol, the delay was determined by timing parenchymal enhancement on DSA power injection (median 8 s, range 4–10 s): enhancement improved, but breathing artifacts increased (from 0 to 27 %). Since the third protocol with a 5 s scan decremented subjective image quality, the second protocol was deemed optimal. Median CNR (range) was 1.7 (0.6–3.2), 2.2 (−1.4–4.0), and 2.1 (−0.3–3.0) for protocol 1, 2, and 3 (p = 0.80). Delineation of perfused segments was possible in 57, 73, and 44 % of scans (p = 0.13). In all C-arm CTs combined, the negative predictive value was 95 % for extrahepatic shunting and 83 % for lack of target segment perfusion.ConclusionAn optimized C-arm CT protocol was developed that can be used to detect extrahepatic shunts and non-perfusion of target segments during RE

  10. Automatic standard plane adjustment on mobile C-Arm CT images of the calcaneus using atlas-based feature registration

    Science.gov (United States)

    Brehler, Michael; Görres, Joseph; Wolf, Ivo; Franke, Jochen; von Recum, Jan; Grützner, Paul A.; Meinzer, Hans-Peter; Nabers, Diana

    2014-03-01

    Intraarticular fractures of the calcaneus are routinely treated by open reduction and internal fixation followed by intraoperative imaging to validate the repositioning of bone fragments. C-Arm CT offers surgeons the possibility to directly verify the alignment of the fracture parts in 3D. Although the device provides more mobility, there is no sufficient information about the device-to-patient orientation for standard plane reconstruction. Hence, physicians have to manually align the image planes in a position that intersects with the articular surfaces. This can be a time-consuming step and imprecise adjustments lead to diagnostic errors. We address this issue by introducing novel semi-/automatic methods for adjustment of the standard planes on mobile C-Arm CT images. With the semi-automatic method, physicians can quickly adjust the planes by setting six points based on anatomical landmarks. The automatic method reconstructs the standard planes in two steps, first SURF keypoints (2D and newly introduced pseudo-3D) are generated for each image slice; secondly, these features are registered to an atlas point set and the parameters of the image planes are transformed accordingly. The accuracy of our method was evaluated on 51 mobile C-Arm CT images from clinical routine with manually adjusted standard planes by three physicians of different expertise. The average time of the experts (46s) deviated from the intermediate user (55s) by 9 seconds. By applying 2D SURF key points 88% of the articular surfaces were intersected correctly by the transformed standard planes with a calculation time of 10 seconds. The pseudo-3D features performed even better with 91% and 8 seconds.

  11. Use of C-Arm Cone Beam CT During Hepatic Radioembolization: Protocol Optimization for Extrahepatic Shunting and Parenchymal Enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Hoven, Andor F. van den, E-mail: a.f.vandenhoven@umcutrecht.nl; Prince, Jip F.; Keizer, Bart de; Vonken, Evert-Jan P. A.; Bruijnen, Rutger C. G.; Verkooijen, Helena M.; Lam, Marnix G. E. H.; Bosch, Maurice A. A. J. van den [University Medical Center Utrecht, Department of Radiology and Nuclear Medicine (Netherlands)

    2016-01-15

    PurposeTo optimize a C-arm computed tomography (CT) protocol for radioembolization (RE), specifically for extrahepatic shunting and parenchymal enhancement.Materials and MethodsA prospective development study was performed per IDEAL recommendations. A literature-based protocol was applied in patients with unresectable and chemorefractory liver malignancies undergoing an angiography before radioembolization. Contrast and scan settings were adjusted stepwise and repeatedly reviewed in a consensus meeting. Afterwards, two independent raters analyzed all scans. A third rater evaluated the SPECT/CT scans as a reference standard for extrahepatic shunting and lack of target segment perfusion.ResultsFifty scans were obtained in 29 procedures. The first protocol, using a 6 s delay and 10 s scan, showed insufficient parenchymal enhancement. In the second protocol, the delay was determined by timing parenchymal enhancement on DSA power injection (median 8 s, range 4–10 s): enhancement improved, but breathing artifacts increased (from 0 to 27 %). Since the third protocol with a 5 s scan decremented subjective image quality, the second protocol was deemed optimal. Median CNR (range) was 1.7 (0.6–3.2), 2.2 (−1.4–4.0), and 2.1 (−0.3–3.0) for protocol 1, 2, and 3 (p = 0.80). Delineation of perfused segments was possible in 57, 73, and 44 % of scans (p = 0.13). In all C-arm CTs combined, the negative predictive value was 95 % for extrahepatic shunting and 83 % for lack of target segment perfusion.ConclusionAn optimized C-arm CT protocol was developed that can be used to detect extrahepatic shunts and non-perfusion of target segments during RE.

  12. Heel Effect: Dose Mapping And Profiling For Mobile C-Arm Fluoroscopy Unit Toshiba SXT-1000A

    International Nuclear Information System (INIS)

    Heel Effect is the well known phenomena in x-ray production. It contributes the effect to image formation and as well as scattered radiation. But there is paucity in the study related to heel effect. This study is for mapping and profiling the dose on the surface of water phantom by using mobile C-arm unit Toshiba SXT-1000A. Based on the result the dose profile is increasing up to about 57 % from anode to cathode bound of the irradiated area. This result and information can be used as a guide to manipulate these phenomena for better image quality and radiation safety for this specific and dedicated fluoroscopy unit. (author)

  13. 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

    Energy Technology Data Exchange (ETDEWEB)

    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.)

  14. 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

    International Nuclear Information System (INIS)

    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.)

  15. Lumbar intervertebral disc puncture under C-arm fluoroscopy: a new rat model of lumbar intervertebral disc degeneration.

    Science.gov (United States)

    Li, Dapeng; Yang, Huilin; Huang, Yonghui; Wu, Yan; Sun, Taicun; Li, Xuefeng

    2014-01-01

    To establish a minimally invasive rat model of lumbar intervertebral disc degeneration (IDD) to better understand the pathophysiology of the human condition. The annulus fibrosus of lumbar level 4-5 (L4-5) and L5-6 discs were punctured by 27-gauge needles using the posterior approach under C-arm fluoroscopic guidance. Magnetic resonance imaging (MRI), histological examination by hematoxylin and eosin (H&E) staining, and reverse transcription polymerase chain reaction (RT-PCR) were performed at baseline and 2, 4, and 8 weeks after disc puncture surgery to determine the degree of degeneration. All sixty discs (thirty rats) were punctured successfully. Only two of thirty rats subjected to the procedure exhibited immediate neurological symptoms. The MRI results indicated a gradual increase in Pfirrmann grade from 4 to 8 weeks post-surgery (PCol2), and Sox9 mRNAs, which encode disc components, decreased gradually post-surgery. In contrast, mRNA expression of type I collagen (Col1), an indicator of fibrosis, increased (P<0.05). The procedure of annular puncture using a 27-gauge needle under C-arm fluoroscopic guidance had a high success rate. Histological, MRI, and RT-PCR results revealed that the rat model of disc degeneration is a progressive pathological process that is similar to human IDD. PMID:24770648

  16. A study on the radiation dose of the orthopaedic surgeon and staff from a mini c-arm fluoroscopy unit

    International Nuclear Information System (INIS)

    In this study, radiation exposure to the surgeon and supporting staff from a mini C-arm unit during fluoroscopically guided orthopaedic surgeries was studied. A Diadose dosemeter and Gamma-Scout meter were used for air-kerma measurements for primary and scattered radiations. The entrance dose of hands, eyes and thyroid of the surgeon was measured during direct observation. Scattered air-kerma rate was measured to quantify the received entrance dose of the supporting staff. During direct observation, the skin-entrance exposure rates of the surgeon's hand, eye and thyroid gland were 8036, 0.85 and 0.9 μGy min-1, respectively. The scattered exposure rate was precipitously dropped beyond the path of the primary radiation beam, and reached 0.51 μGy min-1 at a distance of 40 cm from the beam's central axis. This study showed that the surgeon's hand was the most dose-limiting organ for fluoroscopically guided orthopaedic surgery procedures when it was exposed to primary radiation. The exposure of supporting staff at a working distance of >20 cm from the beam was minimal during fluoroscopy by mini C-arm unit. (authors)

  17. Respiratory Motion Compensation Using Diaphragm Tracking for Cone-Beam C-Arm CT: A Simulation and a Phantom Study

    Directory of Open Access Journals (Sweden)

    Marco Bögel

    2013-01-01

    Full Text Available Long acquisition times lead to image artifacts in thoracic C-arm CT. Motion blur caused by respiratory motion leads to decreased image quality in many clinical applications. We introduce an image-based method to estimate and compensate respiratory motion in C-arm CT based on diaphragm motion. In order to estimate respiratory motion, we track the contour of the diaphragm in the projection image sequence. Using a motion corrected triangulation approach on the diaphragm vertex, we are able to estimate a motion signal. The estimated motion signal is used to compensate for respiratory motion in the target region, for example, heart or lungs. First, we evaluated our approach in a simulation study using XCAT. As ground truth data was available, a quantitative evaluation was performed. We observed an improvement of about 14% using the structural similarity index. In a real phantom study, using the artiCHEST phantom, we investigated the visibility of bronchial tubes in a porcine lung. Compared to an uncompensated scan, the visibility of bronchial structures is improved drastically. Preliminary results indicate that this kind of motion compensation can deliver a first step in reconstruction image quality improvement. Compared to ground truth data, image quality is still considerably reduced.

  18. Simultaneous 3D–2D image registration and C-arm calibration: Application to endovascular image-guided interventions

    Energy Technology Data Exchange (ETDEWEB)

    Mitrović, Uroš [Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, Ljubljana 1000, Slovenia and Cosylab, Control System Laboratory, Teslova ulica 30, Ljubljana 1000 (Slovenia); Pernuš, Franjo [Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, Ljubljana 1000 (Slovenia); Likar, Boštjan; Špiclin, Žiga, E-mail: ziga.spiclin@fe.uni-lj.si [Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, Ljubljana 1000, Slovenia and Sensum, Computer Vision Systems, Tehnološki Park 21, Ljubljana 1000 (Slovenia)

    2015-11-15

    Purpose: Three-dimensional to two-dimensional (3D–2D) image registration is a key to fusion and simultaneous visualization of valuable information contained in 3D pre-interventional and 2D intra-interventional images with the final goal of image guidance of a procedure. In this paper, the authors focus on 3D–2D image registration within the context of intracranial endovascular image-guided interventions (EIGIs), where the 3D and 2D images are generally acquired with the same C-arm system. The accuracy and robustness of any 3D–2D registration method, to be used in a clinical setting, is influenced by (1) the method itself, (2) uncertainty of initial pose of the 3D image from which registration starts, (3) uncertainty of C-arm’s geometry and pose, and (4) the number of 2D intra-interventional images used for registration, which is generally one and at most two. The study of these influences requires rigorous and objective validation of any 3D–2D registration method against a highly accurate reference or “gold standard” registration, performed on clinical image datasets acquired in the context of the intervention. Methods: The registration process is split into two sequential, i.e., initial and final, registration stages. The initial stage is either machine-based or template matching. The latter aims to reduce possibly large in-plane translation errors by matching a projection of the 3D vessel model and 2D image. In the final registration stage, four state-of-the-art intrinsic image-based 3D–2D registration methods, which involve simultaneous refinement of rigid-body and C-arm parameters, are evaluated. For objective validation, the authors acquired an image database of 15 patients undergoing cerebral EIGI, for which accurate gold standard registrations were established by fiducial marker coregistration. Results: Based on target registration error, the obtained success rates of 3D to a single 2D image registration after initial machine-based and

  19. Simultaneous 3D–2D image registration and C-arm calibration: Application to endovascular image-guided interventions

    International Nuclear Information System (INIS)

    Purpose: Three-dimensional to two-dimensional (3D–2D) image registration is a key to fusion and simultaneous visualization of valuable information contained in 3D pre-interventional and 2D intra-interventional images with the final goal of image guidance of a procedure. In this paper, the authors focus on 3D–2D image registration within the context of intracranial endovascular image-guided interventions (EIGIs), where the 3D and 2D images are generally acquired with the same C-arm system. The accuracy and robustness of any 3D–2D registration method, to be used in a clinical setting, is influenced by (1) the method itself, (2) uncertainty of initial pose of the 3D image from which registration starts, (3) uncertainty of C-arm’s geometry and pose, and (4) the number of 2D intra-interventional images used for registration, which is generally one and at most two. The study of these influences requires rigorous and objective validation of any 3D–2D registration method against a highly accurate reference or “gold standard” registration, performed on clinical image datasets acquired in the context of the intervention. Methods: The registration process is split into two sequential, i.e., initial and final, registration stages. The initial stage is either machine-based or template matching. The latter aims to reduce possibly large in-plane translation errors by matching a projection of the 3D vessel model and 2D image. In the final registration stage, four state-of-the-art intrinsic image-based 3D–2D registration methods, which involve simultaneous refinement of rigid-body and C-arm parameters, are evaluated. For objective validation, the authors acquired an image database of 15 patients undergoing cerebral EIGI, for which accurate gold standard registrations were established by fiducial marker coregistration. Results: Based on target registration error, the obtained success rates of 3D to a single 2D image registration after initial machine-based and

  20. 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

    International Nuclear Information System (INIS)

    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

  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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  2. New method of verificating optical flat flatness

    Science.gov (United States)

    Sun, Hao; Li, Xueyuan; Han, Sen; Zhu, Jianrong; Guo, Zhenglai; Fu, Yuegang

    2014-11-01

    Optical flat is commonly used in optical testing instruments, flatness is the most important parameter of forming errors. As measurement criteria, optical flat flatness (OFF) index needs to have good precision. Current measurement in China is heavily dependent on the artificial visual interpretation, through discrete points to characterize the flatness. The efficiency and accuracy of this method can not meet the demand of industrial development. In order to improve the testing efficiency and accuracy of measurement, it is necessary to develop an optical flat verification system, which can obtain all surface information rapidly and efficiently, at the same time, in accordance with current national metrological verification procedures. This paper reviews current optical flat verification method and solves the problems existing in previous test, by using new method and its supporting software. Final results show that the new system can improve verification efficiency and accuracy, by comparing with JJG 28-2000 metrological verification procedures method.

  3. Patient-bounded extrapolation using low-dose priors for volume-of-interest imaging in C-arm CT

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Y.; Maier, A.; Berger, M.; Hornegger, J. [Pattern Recognition Lab, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen 91058 (Germany); Bauer, S. [Siemens AG, Healthcare Sector, Forchheim 91301 (Germany)

    2015-04-15

    Purpose: Three-dimensional (3D) volume-of-interest (VOI) imaging with C-arm systems provides anatomical information in a predefined 3D target region at a considerably low x-ray dose. However, VOI imaging involves laterally truncated projections from which conventional reconstruction algorithms generally yield images with severe truncation artifacts. Heuristic based extrapolation methods, e.g., water cylinder extrapolation, typically rely on techniques that complete the truncated data by means of a continuity assumption and thus appear to be ad-hoc. It is our goal to improve the image quality of VOI imaging by exploiting existing patient-specific prior information in the workflow. Methods: A necessary initial step prior to a 3D acquisition is to isocenter the patient with respect to the target to be scanned. To this end, low-dose fluoroscopic x-ray acquisitions are usually applied from anterior–posterior (AP) and medio-lateral (ML) views. Based on this, the patient is isocentered by repositioning the table. In this work, we present a patient-bounded extrapolation method that makes use of these noncollimated fluoroscopic images to improve image quality in 3D VOI reconstruction. The algorithm first extracts the 2D patient contours from the noncollimated AP and ML fluoroscopic images. These 2D contours are then combined to estimate a volumetric model of the patient. Forward-projecting the shape of the model at the eventually acquired C-arm rotation views gives the patient boundary information in the projection domain. In this manner, we are in the position to substantially improve image quality by enforcing the extrapolated line profiles to end at the known patient boundaries, derived from the 3D shape model estimate. Results: The proposed method was evaluated on eight clinical datasets with different degrees of truncation. The proposed algorithm achieved a relative root mean square error (rRMSE) of about 1.0% with respect to the reference reconstruction on

  4. Analysis the prospects of use of mobile X-ray diagnostic apparatus of the C-arm type

    International Nuclear Information System (INIS)

    The efficiency of using the mobile X-ray apparatus with the C-arm multi-positional support, equipped with a medium-frequency generator and roentgen image amplifier with a digital channel, and device for obtaining hard copies in the diagnostic, surgical and therapeutic practice, is shown and the basis requirements, imposed in various areas on the apparatus of this type (traumatology, orthopedics, hospital wards studies, X-ray endoscopy, X-ray operational units, intervention roentgenology, angiography), are formulated. The technical characteristics are presented and the operation of the national surgical mobile apparatus RTS-612 is described. The experience in the apparatus operation showed, that x-ray surgical complexes, meeting the requirements of the modern public health in the area of traumatology, orthopedics, cardiosurgery, endoscopy, urology and other areas, wherein the X-ray control during the operation is accomplished, may be created on its basis

  5. Cardiac C-arm computed tomography using a 3D + time ROI reconstruction method with spatial and temporal regularization

    Energy Technology Data Exchange (ETDEWEB)

    Mory, Cyril, E-mail: cyril.mory@philips.com [Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, F-69621 Villeurbanne Cedex (France); Philips Research Medisys, 33 rue de Verdun, 92156 Suresnes (France); Auvray, Vincent; Zhang, Bo [Philips Research Medisys, 33 rue de Verdun, 92156 Suresnes (France); Grass, Michael; Schäfer, Dirk [Philips Research, Röntgenstrasse 24–26, D-22335 Hamburg (Germany); Chen, S. James; Carroll, John D. [Department of Medicine, Division of Cardiology, University of Colorado Denver, 12605 East 16th Avenue, Aurora, Colorado 80045 (United States); Rit, Simon [Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1 (France); Centre Léon Bérard, 28 rue Laënnec, F-69373 Lyon (France); Peyrin, Françoise [Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, F-69621 Villeurbanne Cedex (France); X-ray Imaging Group, European Synchrotron, Radiation Facility, BP 220, F-38043 Grenoble Cedex (France); Douek, Philippe; Boussel, Loïc [Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1 (France); Hospices Civils de Lyon, 28 Avenue du Doyen Jean Lépine, 69500 Bron (France)

    2014-02-15

    Purpose: Reconstruction of the beating heart in 3D + time in the catheter laboratory using only the available C-arm system would improve diagnosis, guidance, device sizing, and outcome control for intracardiac interventions, e.g., electrophysiology, valvular disease treatment, structural or congenital heart disease. To obtain such a reconstruction, the patient's electrocardiogram (ECG) must be recorded during the acquisition and used in the reconstruction. In this paper, the authors present a 4D reconstruction method aiming to reconstruct the heart from a single sweep 10 s acquisition. Methods: The authors introduce the 4D RecOnstructiOn using Spatial and TEmporal Regularization (short 4D ROOSTER) method, which reconstructs all cardiac phases at once, as a 3D + time volume. The algorithm alternates between a reconstruction step based on conjugate gradient and four regularization steps: enforcing positivity, averaging along time outside a motion mask that contains the heart and vessels, 3D spatial total variation minimization, and 1D temporal total variation minimization. Results: 4D ROOSTER recovers the different temporal representations of a moving Shepp and Logan phantom, and outperforms both ECG-gated simultaneous algebraic reconstruction technique and prior image constrained compressed sensing on a clinical case. It generates 3D + time reconstructions with sharp edges which can be used, for example, to estimate the patient's left ventricular ejection fraction. Conclusions: 4D ROOSTER can be applied for human cardiac C-arm CT, and potentially in other dynamic tomography areas. It can easily be adapted to other problems as regularization is decoupled from projection and back projection.

  6. C-arm computed tomography parenchymal blood volume measurement in evaluation of hepatocellular carcinoma before transarterial chemoembolization with drug eluting beads

    OpenAIRE

    Syha, Roland; Grözinger, Gerd; Grosse, Ulrich; Maurer, Michael; Zender, Lars; Horger, Marius; Nikolaou, Konstantin; Ketelsen, Dominik

    2015-01-01

    Background C-arm computed tomography (CT) guided intervention is an increasingly applied technique in transarterial chemoembolization (TACE) of hepatocellular carcinoma (HCC). The aim of this study was to analyse the value of parenchymal blood volume (PBV) maps acquired during C-arm CT acquisition, for pre-treatment evaluation and planning of TACE in HCC patients. Methods A total of 64 HCC lesions in 29 patients (median age, 73 years, range, 62–77 years) were included in this retrospective st...

  7. Workflow for the use of a high-resolution image detector in endovascular interventional procedures

    Science.gov (United States)

    Rana, R.; Loughran, B.; Swetadri Vasan, S. N.; Pope, L.; Ionita, C. N.; Siddiqui, A.; Lin, N.; Bednarek, D. R.; Rudin, S.

    2014-03-01

    Endovascular image-guided intervention (EIGI) has become the primary interventional therapy for the most widespread vascular diseases. These procedures involve the insertion of a catheter into the femoral artery, which is then threaded under fluoroscopic guidance to the site of the pathology to be treated. Flat Panel Detectors (FPDs) are normally used for EIGIs; however, once the catheter is guided to the pathological site, high-resolution imaging capabilities can be used for accurately guiding a successful endovascular treatment. The Micro-Angiographic Fluoroscope (MAF) detector provides needed high-resolution, high-sensitivity, and real-time imaging capabilities. An experimental MAF enabled with a Control, Acquisition, Processing, Image Display and Storage (CAPIDS) system was installed and aligned on a detector changer attached to the C-arm of a clinical angiographic unit. The CAPIDS system was developed and implemented using LabVIEW software and provides a user-friendly interface that enables control of several clinical radiographic imaging modes of the MAF including: fluoroscopy, roadmap, radiography, and digital-subtraction-angiography (DSA). Using the automatic controls, the MAF detector can be moved to the deployed position, in front of a standard FPD, whenever higher resolution is needed during angiographic or interventional vascular imaging procedures. To minimize any possible negative impact to image guidance with the two detector systems, it is essential to have a well-designed workflow that enables smooth deployment of the MAF at critical stages of clinical procedures. For the ultimate success of this new imaging capability, a clear understanding of the workflow design is essential. This presentation provides a detailed description and demonstration of such a workflow design.

  8. 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?

    International Nuclear Information System (INIS)

    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.)

  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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  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

    International Nuclear Information System (INIS)

    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

  11. Direct navigation on 3D rotational x-ray data acquired with a mobile propeller C-arm: accuracy and application in functional endoscopic sinus surgery

    International Nuclear Information System (INIS)

    Recently, three-dimensional (3D) rotational x-ray imaging has been combined with navigation technology, enabling direct 3D navigation for minimally invasive image guided interventions. In this study, phantom experiments are used to determine the accuracy of such a navigation set-up for a mobile C-arm with propeller motion. After calibration of the C-arm system, the accuracy is evaluated by pinpointing divots on a special-purpose phantom with known geometry. This evaluation is performed both with and without C-arm motion in between calibration and registration for navigation. The variation caused by each of the individual transformations in the calibration and registration process is also studied. The feasibility of direct navigation on 3D rotational x-ray images for functional endoscopic sinus surgery has been evaluated in a cadaver navigation experiment. Navigation accuracy was approximately 1.0 mm, which is sufficient for functional endoscopic sinus surgery. C-arm motion in between calibration and registration slightly degraded the registration accuracy by approximately 0.3 mm. Standard deviations of each of the transformations were in the range 0.15-0.31 mm. In the cadaver experiment, the navigation images were considered in good correspondence with the endoscopic images by an experienced ENT surgeon. Availability of 3D localization information provided by the navigation system was considered valuable by the ENT surgeon

  12. C-arm CT-guided 3D navigation of percutaneous interventions; C-Bogen-CT-unterstuetzte 3D-Navigation perkutaner Interventionen

    Energy Technology Data Exchange (ETDEWEB)

    Becker, H.C.; Meissner, O.; Waggershauser, T. [Klinikum der Ludwig-Maximilians-Universitaet Muenchen, Campus Grosshadern, Institut fuer Klinische Radiologie, Muenchen (Germany)

    2009-09-15

    So far C-arm CT images were predominantly used for a precise guidance of an endovascular or intra-arterial therapy. A novel combined 3D-navigation C-arm system now also allows cross-sectional and fluoroscopy controlled interventions. Studies have reported about successful CT-image guided navigation with C-arm systems in vertebroplasty. Insertion of the radiofrequency ablation probe is also conceivable for lung and liver tumors that had been labelled with lipiodol. In the future C-arm CT based navigation systems will probably allow simplified and safer complex interventions and simultaneously reduce radiation exposure. (orig.) [German] Bisher wurden CT-Aufnahmen von einem rotierenden C-Bogen-System v. a. fuer die gezielte Unterstuetzung endovaskulaerer und intraarterieller Interventionen verwendet. Mit einer neuen kombinierten 3D-C-Bogen-Navigationseinheit ist es jetzt aber auch moeglich, perkutane Interventionen mit einem C-Bogen-System unter Schichtbild- und fluoroskopischer Kontrolle durchzufuehren. In Studien wird ueber erfolgreiche CT-Bild-gefuehrte Navigationen bei Vertebroplastien mit einem C-Bogen-System berichtet. Vorstellbar ist aber auch das Einbringen von Radiofrequenzsonden in Tumoren von Lunge und Leber, die bereits intraarteriell mit Lipiodol markiert wurden. Voraussichtlich koennen C-Bogen-CT-basierte Navigationssysteme in Zukunft komplexe Interventionen einfacher und sicherer machen und dabei gleichzeitig die Strahlenexposition reduzieren. (orig.)

  13. Direct navigation on 3D rotational x-ray data acquired with a mobile propeller C-arm: accuracy and application in functional endoscopic sinus surgery

    Energy Technology Data Exchange (ETDEWEB)

    Kraats, Everine B van de [Image Sciences Institute, University Medical Center Utrecht (Netherlands); Carelsen, Bart [Academic Medical Center Amsterdam, Medical Physics Department (Netherlands); Fokkens, Wytske J [Academic Medical Center Amsterdam, Department of Otorhinolaryngology (Netherlands); Boon, Sjirk N [Philips Medical Systems, Best (Netherlands); Noordhoek, Niels [Philips Medical Systems, Best (Netherlands); Niessen, Wiro J [Image Sciences Institute, University Medical Center Utrecht (Netherlands); Walsum, Theo van [Image Sciences Institute, University Medical Center Utrecht (Netherlands)

    2005-12-21

    Recently, three-dimensional (3D) rotational x-ray imaging has been combined with navigation technology, enabling direct 3D navigation for minimally invasive image guided interventions. In this study, phantom experiments are used to determine the accuracy of such a navigation set-up for a mobile C-arm with propeller motion. After calibration of the C-arm system, the accuracy is evaluated by pinpointing divots on a special-purpose phantom with known geometry. This evaluation is performed both with and without C-arm motion in between calibration and registration for navigation. The variation caused by each of the individual transformations in the calibration and registration process is also studied. The feasibility of direct navigation on 3D rotational x-ray images for functional endoscopic sinus surgery has been evaluated in a cadaver navigation experiment. Navigation accuracy was approximately 1.0 mm, which is sufficient for functional endoscopic sinus surgery. C-arm motion in between calibration and registration slightly degraded the registration accuracy by approximately 0.3 mm. Standard deviations of each of the transformations were in the range 0.15-0.31 mm. In the cadaver experiment, the navigation images were considered in good correspondence with the endoscopic images by an experienced ENT surgeon. Availability of 3D localization information provided by the navigation system was considered valuable by the ENT surgeon.

  14. A flat laser array aperture

    Science.gov (United States)

    Papadakis, Stergios J.; Ricciardi, Gerald F.; Gross, Michael C.; Krill, Jerry A.

    2010-04-01

    We describe a design concept for a flat (or conformal) thin-plate laser phased-array aperture. The aperture consists of a substrate supporting a grid of single-mode optical waveguides fabricated from a linear electro-optic material. The waveguides are coupled to a single laser source or detector. An arrangement of electrodes provides for two-dimensional beam steering by controlling the phase of the light entering the grid. The electrodes can also be modulated to simultaneously provide atmospheric turbulence modulation for long-range free-space optical communication. An approach for fabrication is also outlined.

  15. Flat for Free Flow

    Institute of Scientific and Technical Information of China (English)

    Yan Manman

    2010-01-01

    @@ Just as Thomas Fried man's famous book,The World Is Flat,if not completely flat,it is anyway tending to be shaped flat.January 1,2010 saw the formation of the China-ASEAN Free Trade Agreement(CAFTA),which was another historical event flattening majority of Asia continent for international trade.

  16. Variance-based iterative image reconstruction from few views in limited-angle C-arm computed tomography

    Science.gov (United States)

    El Hakimi, Wissam; Sakas, Georgios

    2014-03-01

    C-arm cone-beam computed tomography offers CT-like 3D imaging capabilities, but with the additional advantage of being appropriate for interventional suites. Due to the limitations of the data acquisition system, projections are oft acquired in a short scan angular range, resulting in significant artifacts, if conventional analytic formulas are applied. Furthermore, the presence of high-density objects, like metal parts, induces streak-like artifacts, which can obscure relevant anatomy. We present a new algorithm to reduce such artifacts and enhance the quality of reconstructed 3D volume. We make use of the variance of estimated voxel values over all projections to decrease the ground artifact level. The proposed algorithm is less sensitive to data truncation, and does not require explicit estimation of missing data. The number of required images is very low (up to 56 projections), which have several benefits, like significant reduction of patient dose and shortening of the acquisition time. The performance of the proposed method is demonstrated based on simulations and phantom data.

  17. Metal artifact reduction and image processing of cone-beam computed tomography data for mobile C-arm CT devices

    International Nuclear Information System (INIS)

    A new method to reduce artifacts (MAR), produced by high-density objects, especially metal implants (MI), in X-ray CBCT is presented. MIs located in the field of view (FOV) result in artifacts influencing clinical diagnostics and treatments. The novel method reduces metal artifacts by virtually replacing MIs by tissue objects of the same shape. This corrected data can be reconstructed with significantly reduced artifacts. After reconstruction, the segmented 3D MIs were re-inserted into the corrected 3D volume. The method was developed for mobile C-arm CBCTs, where misalignments between original 2D data and forward projections must be adjusted before correction. While doing research on MAR it became obvious that large MIs were hard to segment. Since a good segmentation is a very important prerequisite for an efficient MAR, therefore it was necessary to develop a new segmentation technique by combining two thresholding processes with a reconstruction. These techniques are applied to clinical data and the results are presented. (orig.)

  18. A novel removable shield attached to C-arm units against scattered X-rays from a patient's side

    International Nuclear Information System (INIS)

    We invented a drape-like shield against scattered X-rays that can safely come into contact with medical equipment or people during fluoroscopically guided procedures. The shield can be easily removed from a C-arm unit using one hand. We evaluated the use of the novel removable shield during the endoscopic retrograde cholangiopancreatography (ERCP) procedure. We measured the dose rate of scattered X-rays around endoscopists with and without this removable shield and surveyed the occupational doses to the ERCP staff. We also examined the endurance of the shield. The removable shield reduced the dose rate of scattered X-rays to one-tenth and reduced the monthly dose to an endoscopist by at least two-fifths. For 2.5 years, there was no damage to the shield and no loosening of the seam. The bonding of the hook-and-loop fasteners did not weaken, although the powerful double-sided tapes made especially for plastic did. The removable shield can reduce radiation exposure to the ERCP staff and may contribute to reducing the exposure to the eye lenses of operators. It would also be possible to expand its use to other fluoroscopically guided procedures besides ERCP because it is a light, simple, and useful device. (orig.)

  19. MAMA NUV Flats

    Science.gov (United States)

    Sana, Hugues

    2013-10-01

    This program is aimed at obtaining NUV-MAMA flat-field observations for the construction of pixel-to-pixel flats {p-flats} with a SNR of 100 per binned pixel. The flats are obtained with the DEUTERIUM-lamp and the MR grisms G230M. The actual choice of central wavelength and slit combination depends on the observed count level within each exposure.Note that STIS NUV-MAMA flats are taken every other cycles{i.e. during odd number cycles} in order to not drain the DEUTERIUMlamp lifetime.

  20. Electromagnetic field-based navigation for percutaneous punctures on C-arm CT: experimental evaluation and clinical application

    International Nuclear Information System (INIS)

    The aim of this study was to prospectively evaluate the needle visualization and placement error and use of an electromagnetic field-based tracking navigation device for puncture procedures based on C-arm CT (CACT) images. A commercially available navigation device was mounted on an angiographic X-ray system setup for CACT. After the target was defined, needle placement was performed under real-time visualization of the virtual needle in CACT images. The final, real needle position was assessed by CACT. Punctures were performed in phantoms (n = 76) and in twelve patients (eight biopsies, three drainages, one injection). Procedure times, system error, user error and total error were assessed. In phantoms, mean total error was 2.3 ± 0.9 mm, user error was 1.4 ± 0.8 mm and system error was 1.7 ± 0.8 mm. In the patient study, the targeted puncture was successful in all twelve cases. The mean total error was 5.4 mm ± 1.9 mm (maximum 8.1 mm), user error was 3.7 ± 1.7 mm, system error was 3.2 ± 1.4 mm and mean skin-to-target time was less than 1 min. The navigation device relying on CACT was accurate in terms of needle visualization and useful for needle placement under both experimental and clinical conditions. For more complex procedures, electromagnetic field-based tracking guidance might be of help in facilitating the puncture and reducing both the puncture risk and procedure time. (orig.)

  1. Initial experience of percutaneous transthoracic needle biopsy of lung nodules using C-arm cone-beam CT systems

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Kwang Nam; Goo, Jin Mo; Lee, Hyun Ju; Lee, Youkyung; Kim, Jung Im; Choi, So Young; Kim, Hyo-Cheol [Seoul National University College of Medicine, Department of Radiology, Seoul (Korea); Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea); Park, Chang Min [Seoul National University Hospital, Department of Radiology, Seoul (Korea); Seoul National University College of Medicine, Department of Radiology, Seoul (Korea); Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea)

    2010-09-15

    To describe our initial experience with percutaneous transthoracic biopsy (PCNB) of lung nodules using C-arm cone-beam CT (CBCT). Seventy-one consecutive patients with lung nodules of 30 mm or smaller underwent CBCT-guided PCNB using a coaxial cutting needle. We evaluated the procedure time, coaxial introducer dwell time, the numbers of pleural passages, coaxial introducer repositionings and CT acquisitions, as well as the technical success rate and radiation doses. Diagnostic accuracy, sensitivity, specificity and incidence of complications were also evaluated. PCNB was performed for 71 nodules: 63 solid, 6 part-solid and 2 ground-glass nodules. The procedure time, coaxial introducer dwell time, numbers of pleural passages, coaxial introducer repositionings and CT acquisitions were 17.9 {+-} 5.9 min, 8.7 {+-} 3.8 min, 1.1 {+-} 0.4, 0.2 {+-} 0.5 and 2.9 {+-} 0.7, respectively. The technical success rate was 100% and the radiation dose was 272 {+-} 116 mGy. Thirty-six nodules (50.7%) were diagnosed as malignant, 25 (35.2%) as benign and 10 (14.1%) as indeterminate. Diagnostic accuracy, sensitivity, specificity and incidence of complications were 98.4%, 97%, 100% and 38%, respectively. Complications included pneumothorax in 18 patients (25.4%), haemoptysis in 10 (14.1%) and chest pain in one (1.4%). Under CBCT guidance, PCNB of lung nodules can be performed accurately, providing both real-time fluoroscopic guidance and CT imaging capabilities. (orig.)

  2. C-arm cone-beam CT virtual navigation-guided percutaneous mediastinal mass biopsy: Diagnostic accuracy and complications

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyungjin [Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea, Republic of); Aerospace Medical Group, Air Force Education and Training Command, Jinju (Korea, Republic of); Park, Chang Min; Goo, Jin Mo [Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea, Republic of); Seoul National University, Cancer Research Institute, Seoul (Korea, Republic of); Lee, Sang Min [Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea, Republic of)

    2015-12-15

    To assess the usefulness of C-arm cone-beam computed tomography (CBCT) virtual navigation-guided percutaneous mediastinal mass biopsy in terms of diagnostic accuracy and complication rates. Seventy-eight CBCT virtual navigation-guided percutaneous mediastinal mass biopsies were performed in 75 patients (M:F, 38:37; mean age, 48.55 ± 18.76 years). The procedural details, diagnostic sensitivity, specificity, accuracy and complication rate were investigated. Mean lesion size was 6.80 ± 3.08 cm, skin-to-target distance was 3.67 ± 1.80 cm, core needle biopsy rate was 96.2 % (75/78), needle indwelling time was 9.29 ± 4.34 min, total procedure time was 13.26 ± 5.29 min, number of biopsy specimens obtained was 3.13 ± 1.02, number of CBCTs performed was 3.03 ± 0.68, rate of lesion border discrimination from abutting mediastinal structures on CBCT was 26.9 % (21/78), technical success rate was 100 % (78/78), estimated effective dose was 5.33 ± 4.99 mSv, and the dose area product was 12,723.68 ± 10,665.74 mGy.cm{sup 2}. Among the 78 biopsies, 69 were malignant, 7 were benign and 2 were indeterminate. Diagnostic sensitivity, specificity and accuracy for the diagnosis of malignancies were 97.1 % (67/69), 100 % (7/7) and 97.4 % (74/76), respectively, with a complication rate of 3.85 % (3/78), all of which were small pneumothoraces. CBCT virtual navigation-guided biopsy is a highly accurate and safe procedure for the evaluation of mediastinal lesions. (orig.)

  3. C-arm cone-beam CT virtual navigation-guided percutaneous mediastinal mass biopsy: Diagnostic accuracy and complications

    International Nuclear Information System (INIS)

    To assess the usefulness of C-arm cone-beam computed tomography (CBCT) virtual navigation-guided percutaneous mediastinal mass biopsy in terms of diagnostic accuracy and complication rates. Seventy-eight CBCT virtual navigation-guided percutaneous mediastinal mass biopsies were performed in 75 patients (M:F, 38:37; mean age, 48.55 ± 18.76 years). The procedural details, diagnostic sensitivity, specificity, accuracy and complication rate were investigated. Mean lesion size was 6.80 ± 3.08 cm, skin-to-target distance was 3.67 ± 1.80 cm, core needle biopsy rate was 96.2 % (75/78), needle indwelling time was 9.29 ± 4.34 min, total procedure time was 13.26 ± 5.29 min, number of biopsy specimens obtained was 3.13 ± 1.02, number of CBCTs performed was 3.03 ± 0.68, rate of lesion border discrimination from abutting mediastinal structures on CBCT was 26.9 % (21/78), technical success rate was 100 % (78/78), estimated effective dose was 5.33 ± 4.99 mSv, and the dose area product was 12,723.68 ± 10,665.74 mGy.cm2. Among the 78 biopsies, 69 were malignant, 7 were benign and 2 were indeterminate. Diagnostic sensitivity, specificity and accuracy for the diagnosis of malignancies were 97.1 % (67/69), 100 % (7/7) and 97.4 % (74/76), respectively, with a complication rate of 3.85 % (3/78), all of which were small pneumothoraces. CBCT virtual navigation-guided biopsy is a highly accurate and safe procedure for the evaluation of mediastinal lesions. (orig.)

  4. Strongly Gorenstein Flat Dimensions

    Institute of Scientific and Technical Information of China (English)

    Chun Xia ZHANG; Li Min WANG

    2011-01-01

    This article is concerned with the strongly Gorenstein flat dimensions of modules and rings.We show this dimension has nice properties when the ring is coherent,and extend the well-known Hilbert's syzygy theorem to the strongly Gorenstein flat dimensions of rings.Also,we investigate the strongly Gorenstein flat dimensions of direct products of rings and (almost)excellent extensions of rings.

  5. Creating flat design websites

    CERN Document Server

    Pratas, Antonio

    2014-01-01

    This book contains practical, step-by-step tutorials along with plenty of explanation about designing your flat website. Each section is introduced sequentially, building up your web design skills and completing your website.Creating Flat Design Websites is ideal for you if you are starting on your web development journey, but this book will also benefit seasoned developers wanting to start developing in flat.

  6. MAMA FUV Flats

    Science.gov (United States)

    Mason, Elena

    2012-10-01

    This program aims at obtaining FUV-MAMA flat-field observations to create a new p-flats with a SNR of 100 per {low resolution} pixel. The flats are obtained with the Krypton-lamp and the MR grating G140M, similarly to the cycle 17 and 18 programs. However the exact instrument setup {slit width and central wavelength} might change depending on the desired count level {which will be close to the internally allowed global rate limit}.

  7. C-arm cone beam CT perfusion imaging using the SMART-RECON algorithm to improve temporal sampling density and temporal resolution

    Science.gov (United States)

    Li, Yinsheng; Niu, Kai; Li, Ke; Schafer, Sebastian; Royalty, Kevin; Strother, Charles; Chen, Guang-Hong

    2016-03-01

    In this work, a newly developed reconstruction algorithm, Synchronized MultiArtifact Reduction with Tomographic RECONstruction (SMART-RECON), was applied to C-arm cone beam CT perfusion (CBCTP) imaging. This algorithm contains a special rank regularizer, designed to reduce limited-view artifacts associated with super- short scan reconstructions. As a result, high temporal sampling and temporal resolution image reconstructions were achieved using an interventional C-arm x-ray system. The algorithm was evaluated in terms of the fidelity of the dynamic contrast update curves and the accuracy of perfusion parameters through numerical simulation studies. Results shows that, not only were the dynamic curves accurately recovered (relative root mean square error ∈ [3%, 5%] compared with [13%, 22%] for FBP), but also the noise in the final perfusion maps was dramatically reduced. Compared with filtered backprojection, SMART-RECON generated CBCTP maps with much improved capability in differentiating lesions with perfusion deficits from the surrounding healthy brain tissues.

  8. Intraprocedural blood volume measurement using C-arm CT as a predictor for treatment response of malignant liver tumours undergoing repetitive transarterial chemoembolization (TACE)

    International Nuclear Information System (INIS)

    To evaluate feasibility of measuring parenchymal blood volume (PBV) of malignant hepatic tumours using C-arm CT, test the changes in PBV following repeated transarterial chemoembolization (TACE) and correlate these changes with the change in tumour size in MRI. 111 patients with liver malignancy were included. Patients underwent MRI and TACE in a 4- to 6-week interval. During intervention C-arm CT was performed. Images were post-processed to generate PBV maps. Blood volume data in C-arm CT and change in size in MRI were evaluated. The correlation between PBV and size was tested using Spearman rank test. Pre-interventional PBV maps showed a mean blood volume of 84.5 ml/1000 ml ± 62.0, follow-up PBV maps after multiple TACE demonstrated 61.1 ml/1000 ml ± 57.5. The change in PBV was statistically significant (p = 0.02). Patients with initial tumour blood volume >100 ml/1000 ml dropped 7.1 % in size and 47.2 % in blood volume; 50-100 ml/1000 ml dropped 4.6 % in size and 25.7 % in blood volume; and <50 ml/1000 ml decreased 2.8 % in size and increased 82.2 % in blood volume. PBV measurement of malignant liver tumours using C-arm CT is feasible. Following TACE PBV decreased significantly. Patients with low initial PBV show low local response rates and further increase in blood volume, whereas high initial tumour PBV showed better response to TACE. (orig.)

  9. Intraprocedural blood volume measurement using C-arm CT as a predictor for treatment response of malignant liver tumours undergoing repetitive transarterial chemoembolization (TACE)

    Energy Technology Data Exchange (ETDEWEB)

    Vogl, Thomas J.; Schaefer, Patrik; Lehnert, Thomas; Mbalisike, Emmanuel; Hammerstingl, Renate; Eichler, Katrin; Zangos, Stephan [Johann Wolfgang Goethe-University Frankfurt, Institute for Diagnostic and Interventional Radiology, Frankfurt am Main (Germany); Nour-Eldin, Nour-Eldin A. [Johann Wolfgang Goethe-University Frankfurt, Institute for Diagnostic and Interventional Radiology, Frankfurt am Main (Germany); Cairo University, Department of Radiology, Faculty of Medicine (Kasr Al-Ainy), Cairo (Egypt); Ackermann, Hanns [Johann Wolfgang Goethe-University Frankfurt, Department of Biomedical Statistics, Frankfurt am Main (Germany); Naguib, Nagy N.N. [Johann Wolfgang Goethe-University Frankfurt, Institute for Diagnostic and Interventional Radiology, Frankfurt am Main (Germany); Alexandria University, Department of Radiology, Faculty of Medicine, Alexandria (Egypt)

    2016-03-15

    To evaluate feasibility of measuring parenchymal blood volume (PBV) of malignant hepatic tumours using C-arm CT, test the changes in PBV following repeated transarterial chemoembolization (TACE) and correlate these changes with the change in tumour size in MRI. 111 patients with liver malignancy were included. Patients underwent MRI and TACE in a 4- to 6-week interval. During intervention C-arm CT was performed. Images were post-processed to generate PBV maps. Blood volume data in C-arm CT and change in size in MRI were evaluated. The correlation between PBV and size was tested using Spearman rank test. Pre-interventional PBV maps showed a mean blood volume of 84.5 ml/1000 ml ± 62.0, follow-up PBV maps after multiple TACE demonstrated 61.1 ml/1000 ml ± 57.5. The change in PBV was statistically significant (p = 0.02). Patients with initial tumour blood volume >100 ml/1000 ml dropped 7.1 % in size and 47.2 % in blood volume; 50-100 ml/1000 ml dropped 4.6 % in size and 25.7 % in blood volume; and <50 ml/1000 ml decreased 2.8 % in size and increased 82.2 % in blood volume. PBV measurement of malignant liver tumours using C-arm CT is feasible. Following TACE PBV decreased significantly. Patients with low initial PBV show low local response rates and further increase in blood volume, whereas high initial tumour PBV showed better response to TACE. (orig.)

  10. Application of C-arm CT-guided targeted puncturing technique in performing non-vascular interventional biopsy or interventional therapy

    International Nuclear Information System (INIS)

    Objective: to investigate the clinical value of C-arm CT-guided targeted puncturing technique in performing non, vascular interventional biopsy or interventional therapy. Methods: Thirty, one patients, who were encountered in authors' hospital during the period from July 2010 to September 2010, were involved in this study. C-arm CT-guided percutaneous targeted puncturing biopsy or interventional therapy was performed in all 31 patients. All patients had complete clinical data. The complications and positive rate of biopsy were recorded and analyzed. Results: Under C-arm CT-guidance, percutaneous interventional therapy was carried out in 13 patients. The interventional procedures included radiofrequency ablation therapy for hepatic cellular carcinoma (n=2), pelvic abscess draining (n=1), hepatic abscess draining (n=1), ethanol injection for liver cancer (n=4), sclerotic therapy with ethanol injection for renal cyst (n=2), sclerotic therapy with ethanol injection for liver cyst (n=2) and catheter-indwelling drainage for pancreatic pseudocyst (n=1). percutaneous interventional biopsy was performed in the remaining 18 cases, including liver (n=4), lung (n=7), mediastinum (n=2), bone and soft tissue (n=4) and neck mass (n=1). All the procedures were successfully accomplished, no technique, related complications occurred during the operation. For biopsy examination in 18 cases, the positive rate was 94.4% (17/18) and false, negative results was seen in one case with lung lesion. Conclusion: The percutaneous targeted puncturing technique with C, arm CT-guidance combines the advantages of both CT scanning and fluoroscopy. The use of real, time road, mapping function can effectively guide the puncturing and therapeutic management, which can not only optimize the workflow, save the operation time, but also improve the success rate and technical safety. Therefore, it is of great value to popularize this targeted puncturing technique. (authors)

  11. Analysis of radiation risk to patients from intra-operative use of the mobile X-ray system (C-arm

    Directory of Open Access Journals (Sweden)

    Yang-Sub Lee

    2015-01-01

    Full Text Available Background: The aim of this study was to investigate clinical applications of mobile C-arms and consequent radiation risk, to increase medical attention on radiation protection, and to provide basic data for safe radiation use in the operating room. Materials and Methods: In this study, a total of 374 surgical operations, conducted using a portable fluoroscopic X-ray system from January to March of 2013, were analyzed. Dose summaries produced by the General Electric C-arm and data elements in digital imaging and communications in the medicine header of Ziehm C-arm, fluoroscopy time were used to obtain dose-area product (DAP and effective dose. Corresponding mean and maximum values were calculated, and the resulting data on the frequency of application, fluoroscopy time, DAP, and effective dose were compared and analyzed in terms of surgical specialty and operation types. Results: Orthopedic surgery was the most frequent with 165 cases (44.1%. The highest DAP value and effective dose were found in liver transplant among surgical specialty fields, with mean values of 2.90 ± 3.76 mGy∙m 2 and 58 ± 75.2 mSv, respectively (P = 0.0001. The highest DAP value and effective dose were observed in intra-operative mesenteric portography among types of surgery, showing mean values of 2.90 ± 3.81 mGy∙m 2 and 58.03 ± 76.24 mSv, respectively (P = 0.0001. Conclusion: Because DAP varies significantly across surgical specialties and types of operation, aggressive efforts to understand the effects of radiation dose is critical for radiation protection from intra-operative use of mobile C-arms.

  12. C-arm guided single needle orientation together with the use of a special protractor for the removal of metallic foreign bodies imbedded in soft-tissue

    International Nuclear Information System (INIS)

    Objective: to discuss the effectiveness, minimally-invasiveness and safety of C-arm guided single needle orientation together with the use of a special protractor for the removal of metallic foreign bodies imbedded in soft-tissue. Methods: A total of 38 patients with 137 metal foreign bodies embedded within the soft-tissue were enrolled in this study. The foreign bodies were 0.2-3.5 cm in length and 0.1-1.0 cm in width. The shortest distance from the foreign body to body surface varied between 0.5 cm and 6.5 cm, and the retention time of the foreign bodies ranged from one hour to 10 years. Under C-arm guidance, single needle orientation was established. With the help of the orientation needle, the special protractor was introduced to the foreign body site and then the foreign body was clamped and removed. Results: All foreign bodies were successfully removed with a success rate of 100%. The operation time was (5-35) minutes and the X-ray exposure time required for the removal of one foreign body was (0.5-4) minutes. No procedure-related complications occurred. Conclusion: For the removal of metallic foreign bodies imbedded in soft-tissue, C-arm guided single needle orientation together with the use of a special protractor is a simple, safe and minimally-invasive technique. It is of value of popularize this technique in the clinical practice. (authors)

  13. Flat Pack Toy Design

    Science.gov (United States)

    Hutcheson, Brian

    2007-01-01

    In this article, the author introduces the concept of flat pack toys. Flat pack toys are designed using a template on a single sheet of letter-sized card stock paper. Before being cut out and built into a three-dimensional toy, they are scanned into the computer and uploaded to a website. With the template accessible from the website, anyone with…

  14. Flat Band Quastiperiodic Lattices

    Science.gov (United States)

    Bodyfelt, Joshua; Flach, Sergej; Danieli, Carlo

    2014-03-01

    Translationally invariant lattices with flat bands (FB) in their band structure possess irreducible compact localized flat band states, which can be understood through local rotation to a Fano structure. We present extension of these quasi-1D FB structures under incommensurate lattices, reporting on the FB effects to the Metal-Insulator Transition.

  15. Comparison of C-arm Computed Tomography and Digital Subtraction Angiography in Patients with Chronic Thromboembolic Pulmonary Hypertension

    Energy Technology Data Exchange (ETDEWEB)

    Hinrichs, Jan B., E-mail: hinrichs.jan@mh-hannover.de; Marquardt, Steffen, E-mail: marquardt.steffen@mh-hannover.de; Falck, Christian von, E-mail: falck.christian.von@mh-hannover.de [Hannover Medical School, Department for Diagnostic and Interventional Radiology, German Center for Lung Research (DZL) (Germany); Hoeper, Marius M., E-mail: hoeper.marius@mh-hannover.de; Olsson, Karen M., E-mail: olsson.karen@mh-hannover.de [Hannover Medical School, Clinic for Pneumology, German Center for Lung Research (DZL) (Germany); Wacker, Frank K., E-mail: wacker.frank@mh-hannover.de; Meyer, Bernhard C., E-mail: meyer.bernhard@mh-hannover.de [Hannover Medical School, Department for Diagnostic and Interventional Radiology, German Center for Lung Research (DZL) (Germany)

    2016-01-15

    PurposeTo assess the feasibility and diagnostic performance of contrast-enhanced, C-arm computed tomography (CACT) of the pulmonary arteries compared to digital subtraction angiography (DSA) in patients suffering from chronic thromboembolic pulmonary hypertension (CTEPH).MaterialsFifty-two patients with CTEPH underwent ECG-gated DSA and contrast-enhanced CACT. Two readers (R1, R2) independently evaluated pulmonary artery segments and their sub-segmental branching using DSA and CACT for optimal image quality. Afterwards, the diagnostic findings, i.e., intraluminal filling defects, stenosis, and occlusion, were compared. Inter-modality and inter-observer agreement was calculated, and subsequently consensus reading was done and correlated to a reference standard representing the overall consensus of both modalities. Fisher’s exact test and Cohen’s Kappa were applied.ResultsA total of 1352 pulmonary segments were evaluated, of which 1255 (92.8 %) on DSA and 1256 (92.9 %) on CACT were rated to be fully diagnostic. The main causes of the non-diagnostic image quality were motion artifacts on CACT (R1:37, R2:78) and insufficient contrast enhancement on DSA (R1:59, R2:38). Inter-observer agreement was good for DSA (κ = 0.74) and CACT (κ = 0.75), while inter-modality agreement was moderate (R1: κ = 0.46, R2: κ = 0.47). Compared to the reference standard, the inter-modality agreement for CACT was excellent (κ = 0.96), whereas it was inferior for DSA (κ = 0.61) due to the higher number of abnormal consensus findings read as normal on DSA.ConclusionCACT of the pulmonary arteries is feasible and provides additional information to DSA. CACT has the potential to improve the diagnostic work-up of patients with CTEPH and may be particularly useful prior to surgical or interventional treatment.

  16. Comparison of C-arm Computed Tomography and Digital Subtraction Angiography in Patients with Chronic Thromboembolic Pulmonary Hypertension

    International Nuclear Information System (INIS)

    PurposeTo assess the feasibility and diagnostic performance of contrast-enhanced, C-arm computed tomography (CACT) of the pulmonary arteries compared to digital subtraction angiography (DSA) in patients suffering from chronic thromboembolic pulmonary hypertension (CTEPH).MaterialsFifty-two patients with CTEPH underwent ECG-gated DSA and contrast-enhanced CACT. Two readers (R1, R2) independently evaluated pulmonary artery segments and their sub-segmental branching using DSA and CACT for optimal image quality. Afterwards, the diagnostic findings, i.e., intraluminal filling defects, stenosis, and occlusion, were compared. Inter-modality and inter-observer agreement was calculated, and subsequently consensus reading was done and correlated to a reference standard representing the overall consensus of both modalities. Fisher’s exact test and Cohen’s Kappa were applied.ResultsA total of 1352 pulmonary segments were evaluated, of which 1255 (92.8 %) on DSA and 1256 (92.9 %) on CACT were rated to be fully diagnostic. The main causes of the non-diagnostic image quality were motion artifacts on CACT (R1:37, R2:78) and insufficient contrast enhancement on DSA (R1:59, R2:38). Inter-observer agreement was good for DSA (κ = 0.74) and CACT (κ = 0.75), while inter-modality agreement was moderate (R1: κ = 0.46, R2: κ = 0.47). Compared to the reference standard, the inter-modality agreement for CACT was excellent (κ = 0.96), whereas it was inferior for DSA (κ = 0.61) due to the higher number of abnormal consensus findings read as normal on DSA.ConclusionCACT of the pulmonary arteries is feasible and provides additional information to DSA. CACT has the potential to improve the diagnostic work-up of patients with CTEPH and may be particularly useful prior to surgical or interventional treatment

  17. Extended ellipse-line-ellipse trajectory for long-object cone-beam imaging with a mounted C-arm system

    Science.gov (United States)

    Yu, Zhicong; Lauritsch, Günter; Dennerlein, Frank; Mao, Yanfei; Hornegger, Joachim; Noo, Frédéric

    2016-02-01

    Recent reports show that three-dimensional cone-beam (CB) imaging with a floor-mounted (or ceiling-mounted) C-arm system has become a valuable tool in interventional radiology. Currently, a circular short scan is used for data acquisition, which inevitably yields CB artifacts and a short coverage in the direction of the patient table. To overcome these two limitations, a more sophisticated data acquisition geometry is needed. This geometry should be complete in terms of Tuy’s condition and should allow continuous scanning, while being compatible with the mechanical constraints of mounted C-arm systems. Additionally, the geometry should allow accurate image reconstruction from truncated data. One way to ensure such a feature is to adopt a trajectory that provides full R-line coverage within the field-of-view (FOV). An R-line is any segment of line that connects two points on a source trajectory, and the R-line coverage is the set of points that belong to an R-line. In this work, we propose a novel geometry called the extended ellipse-line-ellipse (ELE) for long-object imaging with a mounted C-arm system. This trajectory is built from modules consisting of two elliptical arcs connected by a line. We demonstrate that the extended ELE can be configured in many ways so that full R-line coverage is guaranteed. Both tight and relaxed parametric settings are presented. All results are supported by extensive mathematical proofs provided in appendices. Our findings make the extended ELE trajectory attractive for axially-extended FOV imaging in interventional radiology.

  18. SU-C-207-02: A Method to Estimate the Average Planar Dose From a C-Arm CBCT Acquisition

    Energy Technology Data Exchange (ETDEWEB)

    Supanich, MP [Rush University Medical Center, Chicago, IL (United States)

    2015-06-15

    Purpose: The planar average dose in a C-arm Cone Beam CT (CBCT) acquisition had been estimated in the past by averaging the four peripheral dose measurements in a CTDI phantom and then using the standard 2/3rds peripheral and 1/3 central CTDIw method (hereafter referred to as Dw). The accuracy of this assumption has not been investigated and the purpose of this work is to test the presumed relationship. Methods: Dose measurements were made in the central plane of two consecutively placed 16cm CTDI phantoms using a 0.6cc ionization chamber at each of the 4 peripheral dose bores and in the central dose bore for a C-arm CBCT protocol. The same setup was scanned with a circular cut-out of radiosensitive gafchromic film positioned between the two phantoms to capture the planar dose distribution. Calibration curves for color pixel value after scanning were generated from film strips irradiated at different known dose levels. The planar average dose for red and green pixel values was calculated by summing the dose values in the irradiated circular film cut out. Dw was calculated using the ionization chamber measurements and film dose values at the location of each of the dose bores. Results: The planar average dose using both the red and green pixel color calibration curves were within 10% agreement of the planar average dose estimated using the Dw method of film dose values at the bore locations. Additionally, an average of the planar average doses calculated using the red and green calibration curves differed from the ionization chamber Dw estimate by only 5%. Conclusion: The method of calculating the planar average dose at the central plane of a C-arm CBCT non-360 rotation by calculating Dw from peripheral and central dose bore measurements is a reasonable approach to estimating the planar average dose. Research Grant, Siemens AG.

  19. SU-C-207-02: A Method to Estimate the Average Planar Dose From a C-Arm CBCT Acquisition

    International Nuclear Information System (INIS)

    Purpose: The planar average dose in a C-arm Cone Beam CT (CBCT) acquisition had been estimated in the past by averaging the four peripheral dose measurements in a CTDI phantom and then using the standard 2/3rds peripheral and 1/3 central CTDIw method (hereafter referred to as Dw). The accuracy of this assumption has not been investigated and the purpose of this work is to test the presumed relationship. Methods: Dose measurements were made in the central plane of two consecutively placed 16cm CTDI phantoms using a 0.6cc ionization chamber at each of the 4 peripheral dose bores and in the central dose bore for a C-arm CBCT protocol. The same setup was scanned with a circular cut-out of radiosensitive gafchromic film positioned between the two phantoms to capture the planar dose distribution. Calibration curves for color pixel value after scanning were generated from film strips irradiated at different known dose levels. The planar average dose for red and green pixel values was calculated by summing the dose values in the irradiated circular film cut out. Dw was calculated using the ionization chamber measurements and film dose values at the location of each of the dose bores. Results: The planar average dose using both the red and green pixel color calibration curves were within 10% agreement of the planar average dose estimated using the Dw method of film dose values at the bore locations. Additionally, an average of the planar average doses calculated using the red and green calibration curves differed from the ionization chamber Dw estimate by only 5%. Conclusion: The method of calculating the planar average dose at the central plane of a C-arm CBCT non-360 rotation by calculating Dw from peripheral and central dose bore measurements is a reasonable approach to estimating the planar average dose. Research Grant, Siemens AG

  20. Individual energy savings for individual flats in blocks of flats

    DEFF Research Database (Denmark)

    Nielsen, Anker; Rose, Jørgen

    2014-01-01

    is distributed on the individual flats. Today, most blocks of flats have individual heat meters to save energy and to ensure a fair distribution of the cost. If all flats have the same indoor temperature, the distribution is correct. In practice, the inhabitants of the different flats maintain......It is well known that similar flats in a block do not have the same energy demand. Part of the explanation for this is the location of the flat in the building, e.g. on the top floor, at the house end or in the middle of the building. It is possible to take this into account when the heating bill...... different indoor temperatures. The result is that heat flows between individual flats. This decreases the energy consumption in the flat where the owner maintains a lower temperature. The neighbouring flats will have higher energy consumption. Calculations were performed for Danish blocks of flats from 1920...

  1. Rocky Flats Compliance Program

    International Nuclear Information System (INIS)

    The Department of Energy (DOE) established the Office of Technology Development (EM-50) (OTD) as an element of Environmental Restoration and Waste Management (EM) in November 1989. The primary objective of the Office of Technology Development, Rocky Flats Compliance Program (RFCP), is to develop altemative treatment technologies for mixed low-level waste (wastes containing both hazardous and radioactive components) to use in bringing the Rocky Flats Plant (RFP) into compliance with Federal and state regulations and agreements. Approximately 48,000 cubic feet of untreated low-level mixed waste, for which treatment has not been specified, are stored at the RFP. The cleanup of the Rocky Flats site is driven by agreements between DOE, the Environmental Protection Agency (EPA), and the Colorado Department of Health (CDH). Under these agreements, a Comprehensive Treatment and Management Plan (CTMP) was drafted to outline the mechanisms by which RFP will achieve compliance with the regulations and agreements. This document describes DOE's strategy to treat low-level mixed waste to meet Land Disposal Restrictions and sets specific milestones related to the regulatory aspects of technology development. These milestones detail schedules for the development of technologies to treat all of the mixed wastes at the RFP. Under the Federal Facilities Compliance Act (FFCA), the CTMP has been incorporated into Rocky Flats Plant Conceptual Site Treatment Plan (CSTP). The CSTP will become the Rocky Flats Plant site Treatment Plan in 1995 and will supersede the CTMP

  2. Implementation of double-C-arm synchronous real-time X-ray positioning system computer aided for aspiration biopsy of small lung lesion

    International Nuclear Information System (INIS)

    Objective: To evaluate the feasibility of a new type of real-time three-dimensional X-ray positioning system for aspiration biopsy of small lung lesions. Methods: Using X-ray imaging technology and X-ray collimator technology and combining with double-C-arm X-ray machine, two different synchronous real-time images were obtained from the vertical to the horizontal plane. Then, with the computer image processing and computer vision processing technologies, dynamic tracking for 3D information of a pulmonary lesion and the needle in aspiration, and the relative position of the two, were established. Results: There was no interference while the two imaging perpendicularly X-ray beam met, two synchronous real-time image acquisition and tracking of a lung lesion and a needle could be completed in free respiration. The average positioning system error was about 0.5 mm, the largest positioning error was about 1.0 mm, real-time display rate was 5 screen/sec. Conclusions: the establishment of a new type of double-C-arm synchronous real-time X-ray positioning system is feasible. It is available for the fast and accurate aspiration biopsy of small lung lesions. (authors)

  3. 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

    Energy Technology Data Exchange (ETDEWEB)

    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

  4. Flat flame burner

    Energy Technology Data Exchange (ETDEWEB)

    Matsumura, Y.; Mitsudomi, H.

    1976-02-24

    Osaka Gas Co., Ltd.'s new flat-flame heat-treatment burner offers lower material costs, reduced combustion noise, and elimination of the need for a high-pressure fuel gas to provide a high-velocity combustion burner. The flat-flame burner contains an air-swirling chamber with a flame opening in one side; the wall defining the flame opening has a small thickness around the opening and a flat outer face. This construction causes the combustion gas to be forced out from the flame opening in a spiral direction by the swirling air current within the air chamber; together with the orifice effect of permitting the flame to emanate from a small opening to an unconfined outer space, this helps assure the formation of a flat flame spreading out over a very wide area for very rapid, uniform, and highly efficient heat treatment of an article to be heated. This approach also permits the thickness of the overall device to be reduced. The supply of combustion air in the form of a swirling stream makes it possible to provide a high-velocity combustion burner without using a high-pressure fuel gas, with the advantage of satisfactory mixture of the fuel gas and combustion air and consequently markedly reduced combustion noise.

  5. Development of flat panel digital radiography system

    International Nuclear Information System (INIS)

    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)

  6. Scattered radiation risk to the lens of the eyes for staff involved in using mobile C-arm fluoroscopy unit: Which position is riskiest?

    International Nuclear Information System (INIS)

    Cataractogenesis is something to be concerned by radiologist and radiographer who work extensively in fluoroscopy. The increasing use of fluoroscopy or interventional fluoroscopy has to come with safety awareness on scattered radiation risk for staff performing the procedure. This study is looking into the radiation risk to the lens of the eyes for staff involved in fluoroscopy using the mobile C-arm fluoroscopy unit. The Toshiba SXT-1000A and Alderson Rando phantom were used in this study. Based on the results, it is found clearly that over couch (OC) procedure is riskier than under couch (UC) procedure. The cathode bound area is clearly riskier than anode bound area especially for UC procedure. More doses (at least +1,568 % of safest position) are received by the lens of the eyes for staff standing at the cathode bound area especially the position opposite to the x-ray tube

  7. Scattered radiation risk to the lens of the eyes for staff involved in using mobile C-arm fluoroscopy unit: Which position is riskiest?

    Energy Technology Data Exchange (ETDEWEB)

    Salleh, H.; Matori, M. K.; Isa, M. J. M. [Agensi Nuklear Malaysia, Bangi, 43000 Kajang, Selangor (Malaysia); Samat, S. B. [Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia)

    2015-09-25

    Cataractogenesis is something to be concerned by radiologist and radiographer who work extensively in fluoroscopy. The increasing use of fluoroscopy or interventional fluoroscopy has to come with safety awareness on scattered radiation risk for staff performing the procedure. This study is looking into the radiation risk to the lens of the eyes for staff involved in fluoroscopy using the mobile C-arm fluoroscopy unit. The Toshiba SXT-1000A and Alderson Rando phantom were used in this study. Based on the results, it is found clearly that over couch (OC) procedure is riskier than under couch (UC) procedure. The cathode bound area is clearly riskier than anode bound area especially for UC procedure. More doses (at least +1,568 % of safest position) are received by the lens of the eyes for staff standing at the cathode bound area especially the position opposite to the x-ray tube.

  8. Scattered radiation risk to the lens of the eyes for staff involved in using mobile C-arm fluoroscopy unit: Which position is riskiest?

    Science.gov (United States)

    Salleh, H.; Samat, S. B.; Matori, M. K.; Isa, M. J. M.

    2015-09-01

    Cataractogenesis is something to be concerned by radiologist and radiographer who work extensively in fluoroscopy. The increasing use of fluoroscopy or interventional fluoroscopy has to come with safety awareness on scattered radiation risk for staff performing the procedure. This study is looking into the radiation risk to the lens of the eyes for staff involved in fluoroscopy using the mobile C-arm fluoroscopy unit. The Toshiba SXT-1000A and Alderson Rando phantom were used in this study. Based on the results, it is found clearly that over couch (OC) procedure is riskier than under couch (UC) procedure. The cathode bound area is clearly riskier than anode bound area especially for UC procedure. More doses (at least +1,568 % of safest position) are received by the lens of the eyes for staff standing at the cathode bound area especially the position opposite to the x-ray tube.

  9. Flat flame burner

    Energy Technology Data Exchange (ETDEWEB)

    Matsumura, Y.; Mitsudomi, H.

    1976-03-09

    Osaka Gas Co., Ltd.'s new flat-flame burner has an air-swirling chamber with a flame opening in one side so constructed that combustion gas is forced out from the flame opening in a spiral direction by the swirling air current within the air chamber. The orifice effect of permitting the flame to emanate from a small opening to an unconfined outer space assures formation of a flat flame spreading out over a very wide area, thereby ensuring very rapid, uniform and highly efficient heat treatment of an article to be heated. With the present invention, moreover, it is possible to materially reduce the thickness of the overall device.

  10. Flat covers of modules

    CERN Document Server

    Xu, Jinzhong

    1996-01-01

    Since the injective envelope and projective cover were defined by Eckmann and Bas in the 1960s, they have had great influence on the development of homological algebra, ring theory and module theory. In the 1980s, Enochs introduced the flat cover and conjectured that every module has such a cover over any ring. This book provides the uniform methods and systematic treatment to study general envelopes and covers with the emphasis on the existence of flat cover. It shows that Enochs' conjecture is true for a large variety of interesting rings, and then presents the applications of the results. Readers with reasonable knowledge in rings and modules will not have difficulty in reading this book. It is suitable as a reference book and textbook for researchers and graduate students who have an interest in this field.

  11. Flat Earth图片

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    欢迎来到这期的光盘介绍。本月的附刊光盘中,除了每月的精彩教程外,您可在光盘中找到15张由Flat Earth友情提供的库存图片。当然还有Twixtor和最新的Acrobat Reader 7。

  12. Exact Piecewise Flat Gravitational Waves

    OpenAIRE

    van de Meent, Maarten

    2011-01-01

    We generalize our previous linear result [1] in obtaining gravitational waves from our piecewise flat model for gravity in 3+1 dimensions to exact piecewise flat configurations describing exact planar gravitational waves. We show explicitly how to construct a piecewise flat spacetime that describes an impulsive plane wavefront. From these wavefronts more general plane waves may be constructed.

  13. IS THE WORLD FLAT?

    Directory of Open Access Journals (Sweden)

    Cristian Încalţărău

    2010-06-01

    Full Text Available Globalization became more and more prominent during the last decades. There is no way to argue that globalization led to more interconnected economies, facilitating the communication and the collaboration around the world. But where is this going? Doesglobalization mean uniformity or diversity? As the world begins to resemble more, the people are trying to distinguish between them more, which can exacerbate nationalistic feeling. Friedman argues that globalization made the world smaller and flatter, allowing all countries to take chance of the available opportunities equally. But is this really true? Although politic and cultural factors can stand in front of a really flat world, what is the key for Chinese and Indian success and which are theirs perspectives?

  14. Flat Helical Nanosieves

    CERN Document Server

    Mei, Shengtao; Hussain, Sajid; Huang, Kun; Ling, Xiaohui; Siew, Shawn Yohanes; Liu, Hong; Teng, Jinghua; Danner, Aaron; Qiu, Cheng-Wei

    2016-01-01

    Compact and miniaturized devices with flexible functionalities are always highly demanded in optical integrated systems. Plasmonic nanosieve has been successfully harnessed as an ultrathin flat platform for complex manipulation of light, including holography, vortex generation and non-linear processes. Compared with most of reported single-functional devices, multi-functional nanosieves might find more complex and novel applications across nano-photonics, optics and nanotechnology. Here, we experimentally demonstrate a promising roadmap for nanosieve-based helical devices, which achieves full manipulations of optical vortices, including its generation, hybridization, spatial multiplexing, focusing and non-diffraction propagation etc., by controlling the geometric phase of spin light via over 121 thousands of spatially-rotated nano-sieves. Thanks to such spin-conversion nanosieve helical elements, it is no longer necessary to employ the conventional two-beam interferometric measurement to characterize optical ...

  15. Flat Bands Under Correlated Perturbations

    OpenAIRE

    Bodyfelt, Joshua D.; Leykam, Daniel; Danieli, Carlo; Yu, Xiaoquan; Flach, Sergej

    2014-01-01

    Flat band networks are characterized by coexistence of dispersive and flat bands. Flat bands (FB) are generated by compact localized eigenstates (CLS) with local network symmetries, based on destructive interference. Correlated disorder and quasiperiodic potentials hybridize CLS without additional renormalization, yet with surprising consequencies: (i) states are expelled from the FB energy $E_{FB}$, (ii) the localization length of eigenstates vanishes as $\\xi \\sim 1 / \\ln (E- E_{FB})$, (iii)...

  16. More Ricci-flat branes

    CERN Document Server

    Figueroa-O'Farrill, J M

    1999-01-01

    Certain supergravity solutions (including domain walls and the magnetic fivebrane) have recently been generalised by Brecher and Perry by relaxing the condition that the brane worldvolume be flat. In this way they obtain examples in which the brane worldvolume is a static spacetime admitting parallel spinors. In this note we simply point out that the restriction to static spacetimes is unnecessary, and in this way exhibit solutions where the brane worldvolume is an indecomposable Ricci-flat lorentzian manifold admitting parallel spinors. We discuss more Ricci-flat fivebranes and domain walls, as well as new Ricci-flat D3-branes.

  17. Three-dimensional conformal arc radiotherapy using a C-arm linear accelerator with a computed tomography on-rail system for prostate cancer: clinical outcomes

    International Nuclear Information System (INIS)

    We report the feasibility and treatment outcomes of image-guided three-dimensional conformal arc radiotherapy (3D-CART) using a C-arm linear accelerator with a computed tomography (CT) on-rail system for localized prostate cancer. Between 2006 and 2011, 282 consecutive patients with localized prostate cancer were treated with in-room CT-guided 3D-CART. Biochemical failure was defined as a rise of at least 2.0 ng/ml beyond the nadir prostate-specific antigen level. Toxicity was scored according to the National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0. A total of 261 patients were analyzed retrospectively (median follow-up: 61.6 months). The median prescribed 3D-CART dose was 82 Gy (2 Gy/fraction, dose range: 78–86 Gy), and 193 of the patients additionally received hormonal therapy. The 5-year overall survival rate was 93.9 %. Among low-, intermediate-, and high-risk patients, 5-year rates of freedom from biochemical failure were 100, 91.5 and 90.3 %, respectively. Rates of grade 2–3 late gastrointestinal and genitourinary toxicities were 2.3 and 11.4 %, respectively. No patient experienced late grade 4 or higher toxicity. In-room CT-guided 3D-CART was feasible and effective for localized prostate cancer. Treatment outcomes were comparable to those previously reported for intensity-modulated radiotherapy

  18. Ellipse-line-ellipse source trajectory and its R-line coverage for long-object cone-beam imaging with a C-arm system

    Science.gov (United States)

    Yu, Z.; Noo, F.; Lauritsch, G.; Dennerlein, F.; Hornegger, J.

    2012-03-01

    Over the last decade, significant progress has been made in terms of treatment of diseases using minimallyinvasive procedures. This progress was facilitated through multiple refinements of the imaging capabilities of C-arm systems in the interventional room, and more sophisticated procedures may become feasible by further refining the performance of these systems. Our primary focus is to eliminate two strong limitations of the current circular cone-beam imaging approach: cone-beam artifacts and limited extent of the volume covered in the direction of the patient bed. To solve this problem, we seek a source trajectory that (i) is complete in terms of Tuy's condition, (ii) can be periodically-repeated without discontinuities to allow long-object imaging, (iii) is practical, and (iv) offers full R-line coverage (an R-line is a line that connects any two source positions). A trajectory that satisfies all of our constraint is the Arc-Extended-Line-Arc(AELA) trajectory. Unfortunately, this trajectory does not allow smooth, continuous scanning at reasonable dose. In this work, we propose a new data acquisition geometry: the Ellipse-Line-Ellipse (ELE) trajectory. This geometry satisfies all of our constraints along with the attractive feature that smooth, continuous scanning at reasonable dose is enabled.

  19. Automatic measurement of contrast bolus distribution in carotid arteries using a C-arm angiography system to support interventional perfusion imaging

    Science.gov (United States)

    Fieselmann, Andreas; Ganguly, Arundhuti; Yu, Deuerling-Zheng; Boese, Jan; Hornegger, Joachim; Fahrig, Rebecca

    2011-03-01

    Brain perfusion CT using a C-arm angiography system capable of CT-like imaging could optimize patient treatment during stroke therapy procedures. For this application, an intra-arterial contrast bolus injection at the aortic arch could be used provided that the location of the injection catheter enables uniform distribution of the bolus into the two common carotid arteries (CCA). In this work, we present a novel method to support optimal injection catheter placement by providing additional quantitative information about the distribution of the contrast bolus into the CCAs. Our fully automatic method uses 2-D digital subtraction angiography (DSA) images following a test bolus injection. It segments both CCAs and computes the relative contrast distribution. We have tested the method in DSA data sets from 5 healthy pigs and our method achieved successful segmentation of both CCAs in all data sets. The results showed that the contrast is uniformly distributed (mean relative difference less or equal than 10%) if the injection location is properly chosen.

  20. The value of combined soft-tissue and vessel visualisation before transarterial chemoembolisation of the liver using C-arm computed tomography

    International Nuclear Information System (INIS)

    The purpose of the study was to prospectively evaluate intrahepatic vessel depiction on C-arm CT (CACT) and the influence of the additional combined tissue and three-dimensional vessel visualisation on the positioning of the TACE catheter in comparison to DSA alone. Thirty consecutive patients scheduled for their first transarterial chemoembolisation underwent biphasic CACT and DSA of the liver. After assessing the DSA images for procedure planning, the CACT images were reviewed. The number and origin of the tumour-feeding arteries and the ideal position of the catheter for TACE on both DSA and CACT were assessed and correlated. The number of vessels identified as tumour feeders in each patient was significantly higher using additional CACT than on DSA alone (CACT: 4.0 ± 1.7; DSA: 3.3 ± 1.4; P = 0.003, t-test). After considering CACT, in 50% of the patients the catheter position was changed for TACE. Segmental portal vein thrombosis was seen in three patients on CACT, but in only one on DSA. As CACT depicts soft tissue and small vessels with high spatial resolution, tumour vessel allocation is facilitated, and ideal catheter position for TACE can be more accurately identified. The high impact of CACT on the TACE procedure suggests the benefits of its routine use for all patients undergoing their first TACE. (orig.)

  1. The value of combined soft-tissue and vessel visualisation before transarterial chemoembolisation of the liver using C-arm computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, B.C.; Witschel, M.; Frericks, B.B.; Voges, M.; Wolf, K.J. [Charite-University Hospital, Campus Benjamin Franklin, Department of Radiology and Nuclear Medicine, Berlin (Germany); Hopfenmueller, W. [Charite-University Hospital, Campus Benjamin Franklin, Department of Biometry and Clinical Epidemiology, Berlin (Germany); Wacker, F.K. [Charite-University Hospital, Campus Benjamin Franklin, Department of Radiology and Nuclear Medicine, Berlin (Germany); The Johns Hopkins Hospital, Radiology Department, Division of Vascular and Interventional Radiology, Baltimore, MD (United States)

    2009-09-15

    The purpose of the study was to prospectively evaluate intrahepatic vessel depiction on C-arm CT (CACT) and the influence of the additional combined tissue and three-dimensional vessel visualisation on the positioning of the TACE catheter in comparison to DSA alone. Thirty consecutive patients scheduled for their first transarterial chemoembolisation underwent biphasic CACT and DSA of the liver. After assessing the DSA images for procedure planning, the CACT images were reviewed. The number and origin of the tumour-feeding arteries and the ideal position of the catheter for TACE on both DSA and CACT were assessed and correlated. The number of vessels identified as tumour feeders in each patient was significantly higher using additional CACT than on DSA alone (CACT: 4.0 {+-} 1.7; DSA: 3.3 {+-} 1.4; P = 0.003, t-test). After considering CACT, in 50% of the patients the catheter position was changed for TACE. Segmental portal vein thrombosis was seen in three patients on CACT, but in only one on DSA. As CACT depicts soft tissue and small vessels with high spatial resolution, tumour vessel allocation is facilitated, and ideal catheter position for TACE can be more accurately identified. The high impact of CACT on the TACE procedure suggests the benefits of its routine use for all patients undergoing their first TACE. (orig.)

  2. A novel removable shield attached to C-arm units against scattered X-rays from a patient's side

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Hiroshige [Hokkaido Social Insurance Hospital, Department of Radiology, Sapporo, Hokkaido (Japan); Kanazawa University, Department of Quantum Medical Technology, Division of Health Sciences, Graduate School of Medical Science, Kanazawa, Ishikawa (Japan); Koshida, Kichiro; Matsubara, Kosuke [Kanazawa University, School of Health Sciences, College of Medical, Pharmaceutical and Health Sciences, Kanazawa, Ishikawa (Japan); Ishigamori, Osamu [Hokkaido Social Insurance Hospital, Department of Radiology, Sapporo, Hokkaido (Japan)

    2014-08-15

    We invented a drape-like shield against scattered X-rays that can safely come into contact with medical equipment or people during fluoroscopically guided procedures. The shield can be easily removed from a C-arm unit using one hand. We evaluated the use of the novel removable shield during the endoscopic retrograde cholangiopancreatography (ERCP) procedure. We measured the dose rate of scattered X-rays around endoscopists with and without this removable shield and surveyed the occupational doses to the ERCP staff. We also examined the endurance of the shield. The removable shield reduced the dose rate of scattered X-rays to one-tenth and reduced the monthly dose to an endoscopist by at least two-fifths. For 2.5 years, there was no damage to the shield and no loosening of the seam. The bonding of the hook-and-loop fasteners did not weaken, although the powerful double-sided tapes made especially for plastic did. The removable shield can reduce radiation exposure to the ERCP staff and may contribute to reducing the exposure to the eye lenses of operators. It would also be possible to expand its use to other fluoroscopically guided procedures besides ERCP because it is a light, simple, and useful device. (orig.)

  3. Is classical flat Kasner spacetime flat in quantum gravity?

    Science.gov (United States)

    Singh, Parampreet

    2016-05-01

    Quantum nature of classical flat Kasner spacetime is studied using effective spacetime description in loop quantum cosmology (LQC). We find that even though the spacetime curvature vanishes at the classical level, nontrivial quantum gravitational effects can arise. For the standard loop quantization of Bianchi-I spacetime, which uniquely yields universal bounds on expansion and shear scalars and results in a generic resolution of strong singularities, we find that a flat Kasner metric is not a physical solution of the effective spacetime description, except in a limit. The lack of a flat Kasner metric at the quantum level results from a novel feature of the loop quantum Bianchi-I spacetime: quantum geometry induces nonvanishing spacetime curvature components, making it not Ricci flat even when no matter is present. The noncurvature singularity of the classical flat Kasner spacetime is avoided, and the effective spacetime transits from a flat Kasner spacetime in asymptotic future, to a Minkowski spacetime in asymptotic past. Interestingly, for an alternate loop quantization which does not share some of the fine features of the standard quantization, flat Kasner spacetime with expected classical features exists. In this case, even with nontrivial quantum geometric effects, the spacetime curvature vanishes. These examples show that the character of even a flat classical vacuum spacetime can alter in a fundamental way in quantum gravity and is sensitive to the quantization procedure.

  4. Silicon detectors

    International Nuclear Information System (INIS)

    The status and recent progress of silicon detectors for high energy physics is reviewed. Emphasis is put on detectors with high spatial resolution and the use of silicon detectors in calorimeters. (orig.)

  5. Alkali metal ionization detector

    Science.gov (United States)

    Bauerle, James E.; Reed, William H.; Berkey, Edgar

    1978-01-01

    Variations in the conventional filament and collector electrodes of an alkali metal ionization detector, including the substitution of helical electrode configurations for either the conventional wire filament or flat plate collector; or, the substitution of a plurality of discrete filament electrodes providing an in situ capability for transferring from an operationally defective filament electrode to a previously unused filament electrode without removing the alkali metal ionization detector from the monitored environment. In particular, the helical collector arrangement which is coaxially disposed about the filament electrode, i.e. the thermal ionizer, provides an improved collection of positive ions developed by the filament electrode. The helical filament design, on the other hand, provides the advantage of an increased surface area for ionization of alkali metal-bearing species in a monitored gas environment as well as providing a relatively strong electric field for collecting the ions at the collector electrode about which the helical filament electrode is coaxially positioned. Alternatively, both the filament and collector electrodes can be helical. Furthermore, the operation of the conventional alkali metal ionization detector as a leak detector can be simplified as to cost and complexity, by operating the detector at a reduced collector potential while maintaining the sensitivity of the alkali metal ionization detector adequate for the relatively low concentration of alkali vapor and aerosol typically encountered in leak detection applications.

  6. Design of a submersible, low-cost, flat-response net radiometer

    International Nuclear Information System (INIS)

    A fundamental analysis and design of a flat-response, temperature-compensated net radiometer is presented. The developed detector was tested in the laboratory, and its suitability was assessed for a fixed level and scanning measurements. Practical recommendations for field use as a fixed level or scanning radiation transmission detector are discussed

  7. Exact piecewise flat gravitational waves

    NARCIS (Netherlands)

    van de Meent, M.

    2011-01-01

    We generalize our previous linear result (van de Meent 2011 Class. Quantum Grav 28 075005) in obtaining gravitational waves from our piecewise flat model for gravity in 3+1 dimensions to exact piecewise flat configurations describing exact planar gravitational waves. We show explicitly how to constr

  8. Asymptotic Flatness in Rainbow Gravity

    OpenAIRE

    Hackett, Jonathan

    2005-01-01

    A construction of conformal infinity in null and spatial directions is constructed for the Rainbow-flat space-time corresponding to doubly special relativity. From this construction a definition of asymptotic DSRness is put forward which is compatible with the correspondence principle of Rainbow gravity. Furthermore a result equating asymptotically flat space-times with asymptotically DSR spacetimes is presented.

  9. Comparison of the clinical accuracy of cervical (C2-C7) pedicle screw insertion assisted by fluoroscopy, computed tomography-based navigation, and intraoperative three-dimensional C-arm navigation

    Institute of Scientific and Technical Information of China (English)

    LIU Ya-jun; TIAN Wei; LIU Bo; LI Qin; HU Lin; LI Zhi-yu; YUAN Qiang; L(U) Yan-wei; SUN Yu-zhen

    2010-01-01

    Background The complicated anatomy of the cervical spine and the variation among pedicles reduces the accuracy and increases the risk of neurovascular complications associated with screw implantation in this region. In this study, we compared the accuracy of cervical (C2-C7) pedicle screw fixation assisted by X-ray fluoroscopy, computed tomography (CT)-based navigation, or intraoperative three-dimensional (3D) C-arm navigation.Methods This prospective cohort study was performed in 82 consecutive patients who underwent cervical pedicle screw fixation. The accuracy of screw insertion was assessed by postoperative CT scan with 3D reconstruction. The accuracy of screw insertion was assessed as: excellent (screw completely within pedicle); acceptable (≤ 1 mm screw outside pedicle cortex); poor (>1 mm screw outside pedicle cortex).Results A total of 145 screws were inserted in 24 patients who underwent C-arm fluoroscopy. Of these, 96 screws (66.2%) were excellent, 37 (25.5%) were acceptable, and 12 (8.3%) were poor. One hundred and fifty-nine screws were inserted in 29 patients in the CT-based navigation group. Among these, 141 (88.7%) were excellent, 14 (8.8%) were acceptable, and 4 (2.5%) were poor. A total of 140 screws were inserted in 29 patients in the intraoperative 3D C-arm navigation group, of which 127 (90.7%) were excellent, and 13 (9.3%) were acceptable. No severe or permanent neurovascular complications associated with screw insertion were observed in any patient.Conclusione CT-based and intraoperative 3D C-arm navigation were similarly accurate, and were both significantly more accurate than C-arm fluoroscopy for guiding cervical pedicle screw fixation. They were able to accurately guide the angle and depth of screw placement using visual 3D images. These two techniques are therefore preferable for high-risk cervical pedicle screw fixation. The ease and convenience of intraoperative 3D C-arm navigation suggests that it may replace virtual

  10. Ionization detector

    International Nuclear Information System (INIS)

    A novel ionization detector for use in X-ray tomography is described in detail. To achieve the ultimate resolution, the use of small detectors is necessary and, for ionization detectors, this implies using xenon gas at high pressure. Conventional small detectors can suffer from ''bowing'' but the present design overcomes their problems. (U.K.)

  11. Use of short roll C-arm computed tomography and fully automated 3D analysis tools to guide transcatheter aortic valve replacement.

    Science.gov (United States)

    Kim, Michael S; Bracken, John; Eshuis, Peter; Chen, S Y James; Fullerton, David; Cleveland, Joseph; Messenger, John C; Carroll, John D

    2016-07-01

    Determination of the coplanar view is a critical component of transcatheter aortic valve replacement (TAVR). The safety and accuracy of a novel reduced angular range C-arm computed tomography (CACT) approach coupled with a fully automated 3D analysis tool package to predict the coplanar view in TAVR was evaluated. Fifty-seven patients with severe symptomatic aortic stenosis deemed prohibitive-risk for surgery and who underwent TAVR were enrolled. Patients were randomized 2:1 to CACT vs. angiography (control) in estimating the coplanar view. These approaches to determine the coplanar view were compared quantitatively. Radiation doses needed to determine the coplanar view were recorded for both the CACT and control patients. Use of CACT offered good agreement with the actual angiographic view utilized during TAVR in 34 out of 41 cases in which a CACT scan was performed (83 %). For these 34 cases, the mean angular magnitude difference, taking into account both oblique and cranial/caudal angulation, was 1.3° ± 0.4°, while the maximum difference was 7.3°. There were no significant differences in the mean total radiation dose delivered to patients between the CACT and control groups as measured by either dose area product (207.8 ± 15.2 Gy cm(2) vs. 186.1 ± 25.3 Gy cm(2), P = 0.47) or air kerma (1287.6 ± 117.7 mGy vs. 1098.9 ± 143.8 mGy, P = 0.32). Use of reduced-angular range CACT coupled with fully automated 3D analysis tools is a safe, practical, and feasible method by which to determine the optimal angiographic deployment view for guiding TAVR procedures. PMID:27091735

  12. Irritated Method for Flat warts

    Institute of Scientific and Technical Information of China (English)

    LiBingxu

    2004-01-01

    Summary Background The relation between spontaneous regression of Flat warts and T cells depended immunity was confirmed. Cells immunity against HPV was induced by presenting of HPV related antigens, and thrived by cytokine and some chemistry agent. So how to make HPV which incubated in keratinocyte to present PHV antigens and keratinocyte to secret cytokine or chemistry agents should be a pursuance for dermatologist who are looking for a efficient method to deal with flat warts. Present research had exhibited inflammable agents can induce dermatitis when apply to the skin surface, so it might bring flat warts to spontaneous regression. Objective To observe the effectiveness of irritant drugs on flat warts, and at same time to understand more on the mechanism of the regression. Methods Compared with Control we treat 88 case of flat warts with retinoid gel or 3% hydrogen peroxide solution plus 5 % salicylic acid cream (HPSC). Results Both retinoid gel and HPSC reveal significant effect on flat warts. Conclusion Retinoid gel or SPHC was effective on the treatment of flat warts. The possible explanation for this is the drugs when put on the skin will induce dermatitis and dissolve or denude keratin.

  13. Is classical flat Kasner spacetime flat in quantum gravity?

    OpenAIRE

    Singh, Parampreet

    2016-01-01

    Quantum nature of classical flat Kasner spacetime is studied using effective spacetime description in loop quantum cosmology. We find that even though the spacetime curvature vanishes at the classical level, non-trivial quantum gravitational effects can arise. For the standard loop quantization of Bianchi-I spacetime, which uniquely yields universal bounds on expansion and shear scalars and results in a generic resolution of strong singularities, we find that a flat Kasner metric is not a phy...

  14. Is classical flat Kasner spacetime flat in quantum gravity?

    CERN Document Server

    Singh, Parampreet

    2016-01-01

    Quantum nature of classical flat Kasner spacetime is studied using effective spacetime description in loop quantum cosmology. We find that even though the spacetime curvature vanishes at the classical level, non-trivial quantum gravitational effects can arise. For the standard loop quantization of Bianchi-I spacetime, which uniquely yields universal bounds on expansion and shear scalars and results in a generic resolution of strong singularities, we find that a flat Kasner metric is not a physical solution of the effective spacetime description, except in a limit. The lack of a flat Kasner metric at the quantum level results from a novel feature of the loop quantum Bianchi-I spacetime: quantum geometry induces non-vanishing spacetime curvature components, making it not Ricci flat even when no matter is present. The non-curvature singularity of the classical flat Kasner spacetime is avoided, and the effective spacetime transits from a flat Kasner spacetime in asymptotic future, to a Minkowski spacetime in asym...

  15. Evaluation of 3D-CTA and flat detector DSA in diagnosing intracranial aneurysms:a comparative analysis%三维CT血管造影与平板DSA对颅内动脉瘤诊断价值的对比分析

    Institute of Scientific and Technical Information of China (English)

    游梦星; 虞希祥; 林永胜; 郝伟远; 吴宽

    2011-01-01

    Objective To evaluate three-dimension computed tomographic angiography (3D-CTA) and flat detector DSA in diagnosing intracranial aneurysms through a comparative analysis. Methods A total of 44 consecutive spontaneous suharachnoid hemorrhage (SSAH) patients with suspected aneurysms underwent both 3D-CTA and flat detector DSA (including both 2D-DSA and 3D-DSA) examinations simultaneously.According to the diameter of intracranial aneurysms the patients were divided into two groups : < 3 mm group and ≥ 3 mm group. Results A total of 46 aneuiysms, which were confirmecl by surgical operation or interventional therapy, were found in 36 patients. The sensitivity, specificity, positive predictive value and negative predictive value of 3D-CTA (2D-DSA, 3D-DSA-VR and 3D-DSA-MIP) in detecting intracranial aneurysms for all patients was 83.33% (77.78%, 100% and 94.44%) , 75% (75%, 100% and 100%), 75% (73.68%, 100% and 100%) and 66.67% (75%, 100% and 100%), respectively. No significant difference in the diameter of aneurysm (Z = -0.178, P = 0.859 > 0.1) existed between 3D-CTA (VR) and 3D-DSA (VR) when Wilcoxon paired signed-rank test was used. Statistically significant difference in displaying the aneurismal neck and its relation to the parent artery existed between 3D-CTA (VR) and 2D-DSA (P < 0.05) . and between 3D-CTA (VR) and 3D-DSA (VR) (P < 0.05) as well. although no significant difference was found between 3D-CTA (VR) and 3D-DSA (MIP) (P > 0.05). Conclusion For the diagnosis of intracranial aneurysms with diameter≥ 3 mm. 3D-CTA is quite effective and accurate. It can be used as a routine screening means. However. 3D-CTA carries high rate of missed diagnosis and misdiagnosis for intracranial aneurysms with the diameter < 3 mm. Therefore. 3D-DSA should be adopted in suspicious cases of SSAH in whom the intracranial aneurysms are not demonstrated on 3D-CTA. With the wide use of the flat detector DSA, 3D-DSA should be carried out

  16. SU-E-CAMPUS-I-04: Automatic Skin-Dose Mapping for An Angiographic System with a Region-Of-Interest, High-Resolution Detector

    Energy Technology Data Exchange (ETDEWEB)

    Vijayan, S; Rana, V [Department of Physiology and Biophysics, Toshiba Stroke and Vascular Research Center (United States); Setlur Nagesh, S [Toshiba Stroke and Vascular Research Center (United States); Ionita, C [Department of Biomedical Engineering, University at Buffalo (State University of New York), Buffalo, NY (United States); Rudin, S [Department of Radiology, Department of Physiology and Biophysics, Toshiba Stroke and Vascular Research Center, Department of Biomedical Engineering, University at Buffalo (State University of New York), Buffalo, NY (United States); Bednarek, D [Department of Radiology, Department of Physiology and Biophysics, Toshiba Stroke and Vascular Research Center (United States)

    2014-06-15

    Purpose: Our real-time skin dose tracking system (DTS) has been upgraded to monitor dose for the micro-angiographic fluoroscope (MAF), a high-resolution, small field-of-view x-ray detector. Methods: The MAF has been mounted on a changer on a clinical C-Arm gantry so it can be used interchangeably with the standard flat-panel detector (FPD) during neuro-interventional procedures when high resolution is needed in a region-of-interest. To monitor patient skin dose when using the MAF, our DTS has been modified to automatically account for the change in scatter for the very small MAF FOV and to provide separated dose distributions for each detector. The DTS is able to provide a color-coded mapping of the cumulative skin dose on a 3D graphic model of the patient. To determine the correct entrance skin exposure to be applied by the DTS, a correction factor was determined by measuring the exposure at the entrance surface of a skull phantom with an ionization chamber as a function of entrance beam size for various beam filters and kVps. Entrance exposure measurements included primary radiation, patient backscatter and table forward scatter. To allow separation of the dose from each detector, a parameter log is kept that allows a replay of the procedure exposure events and recalculation of the dose components.The graphic display can then be constructed showing the dose distribution from the MAF and FPD separately or together. Results: The DTS is able to provide separate displays of dose for the MAF and FPD with field-size specific scatter corrections. These measured corrections change from about 49% down to 10% when changing from the FPD to the MAF. Conclusion: The upgraded DTS allows identification of the patient skin dose delivered when using each detector in order to achieve improved dose management as well as to facilitate peak skin-dose reduction through dose spreading. Research supported in part by Toshiba Medical Systems Corporation and NIH Grants R43FD0158401, R44FD

  17. SU-E-CAMPUS-I-04: Automatic Skin-Dose Mapping for An Angiographic System with a Region-Of-Interest, High-Resolution Detector

    International Nuclear Information System (INIS)

    Purpose: Our real-time skin dose tracking system (DTS) has been upgraded to monitor dose for the micro-angiographic fluoroscope (MAF), a high-resolution, small field-of-view x-ray detector. Methods: The MAF has been mounted on a changer on a clinical C-Arm gantry so it can be used interchangeably with the standard flat-panel detector (FPD) during neuro-interventional procedures when high resolution is needed in a region-of-interest. To monitor patient skin dose when using the MAF, our DTS has been modified to automatically account for the change in scatter for the very small MAF FOV and to provide separated dose distributions for each detector. The DTS is able to provide a color-coded mapping of the cumulative skin dose on a 3D graphic model of the patient. To determine the correct entrance skin exposure to be applied by the DTS, a correction factor was determined by measuring the exposure at the entrance surface of a skull phantom with an ionization chamber as a function of entrance beam size for various beam filters and kVps. Entrance exposure measurements included primary radiation, patient backscatter and table forward scatter. To allow separation of the dose from each detector, a parameter log is kept that allows a replay of the procedure exposure events and recalculation of the dose components.The graphic display can then be constructed showing the dose distribution from the MAF and FPD separately or together. Results: The DTS is able to provide separate displays of dose for the MAF and FPD with field-size specific scatter corrections. These measured corrections change from about 49% down to 10% when changing from the FPD to the MAF. Conclusion: The upgraded DTS allows identification of the patient skin dose delivered when using each detector in order to achieve improved dose management as well as to facilitate peak skin-dose reduction through dose spreading. Research supported in part by Toshiba Medical Systems Corporation and NIH Grants R43FD0158401, R44FD

  18. Research on Flat Solar Collector

    OpenAIRE

    Kavolynas, Antanas

    2005-01-01

    The Thesis analyzes one of the spheres of alternative energy supply – the solar energy. The main objective of the Thesis is to determine the energy rates of the solar collector and its accumulative capacity. The Paper introduces a stand on the solar collector research which consists of a flat solar collector, heat accumulator and auxiliary equipment. The research object of the Thesis is a laboratory flat solar collector and its system. The Thesis analyses the constructions of the solar collec...

  19. Scintillation detector of secondary electrons

    International Nuclear Information System (INIS)

    The detector is based on powder or single crystal scintillators and is formed by a scintillator shaped as a cone, a truncated cone or a flat disk plate. The scintillator is accommodated in the cylindrical cage of the detector under the level of the cage's front, and is attached to the front of a light guide which is coaxially aligned in the cylindrical detector cage. To increase the collecting efficiency for secondary electrons impinging on the scintillator, an electron-optical diaphragm with a positive voltage is positioned in the detector cage and screened by means of a screening tube with a ground potential. This diaphragm also contributes to secondary electron focusing to the scintillator centre. (Z.S). 2 figs

  20. On Flat Objects of Finitely Accessible Categories

    Directory of Open Access Journals (Sweden)

    Septimiu Crivei

    2013-01-01

    Full Text Available Flat objects of a finitely accessible additive category are described in terms of some objects of the associated functor category of , called strongly flat functors. We study closure properties of the class of strongly flat functors, and we use them to deduce the known result that every object of a finitely accessible abelian category has a flat cover.

  1. Dual polarization flat plate antenna

    Science.gov (United States)

    Kelly, Kenneth C.

    Rectangular waveguides with radiating slots are used in groups to form planar array microwave antennas with large apertures and small depth. Such flat plate antennas are widely used on spacecraft and aircraft. Typically, flat plate antennas provide fixed linear polarization. The present paper describes a new flat plate antenna which produces two coincident beams that are distinguished by their orthogonal linear polarizations. The antenna has two ports, one for each of the coicident beams. Completely external to the antenna, connecting a simple network to those terminal ports enables the antenna to provide right circular polarization from one port and left from the other. A different external network enables the antenna to have arbitrarily adjustable polarizations.

  2. The Fallacies of Flatness: Thomas Friedman's "The World Is Flat"

    Science.gov (United States)

    Abowitz, Kathleen Knight; Roberts, Jay

    2007-01-01

    Thomas Friedman's best-selling "The World is Flat" has exerted much influence in the west by providing both an accessible analysis of globalization and its economic and social effects, and a powerful cultural metaphor for globalization. In this review, we more closely examine Friedman's notion of the social contract, the moral center of his…

  3. Nonlocal gravity: Conformally flat spacetimes

    CERN Document Server

    Bini, Donato

    2016-01-01

    The field equations of the recent nonlocal generalization of Einstein's theory of gravitation are presented in a form that is reminiscent of general relativity. The implications of the nonlocal field equations are studied in the case of conformally flat spacetimes. Even in this simple case, the field equations are intractable. Therefore, to gain insight into the nature of these equations, we investigate the structure of nonlocal gravity in two-dimensional spacetimes. While any smooth 2D spacetime is conformally flat and satisfies Einstein's field equations, only a subset containing either a Killing vector or a homothetic Killing vector can satisfy the field equations of nonlocal gravity.

  4. The complexity of flat origami

    Energy Technology Data Exchange (ETDEWEB)

    Bern, M. [Xerox, Palo Alto, CA (United States); Hayes, B. [ParcPlace-Digitalk, Inc., Sunnyvale, CA (United States)

    1996-12-31

    We study a basic problem in mathematical origami: determine if a given crease pattern can be folded to a flat origami. We show that assigning mountain and valley folds is NP-hard. We also show that determining a suitable overlap order for flaps is NP-hard, even assuming a valid mountain and valley assignment.

  5. Flat space physics from holography

    CERN Document Server

    Bousso, R

    2004-01-01

    We point out that aspects of quantum mechanics can be derived from the holographic principle, using only a perturbative limit of classical general relativity. In flat space, the covariant entropy bound reduces to the Bekenstein bound. The latter does not contain Newton's constant and cannot operate via gravitational backreaction. Instead, it is protected by - and in this sense, predicts - the Heisenberg uncertainty principle

  6. Rocky Flats CAAS System Recalibrated, Retested, and Analyzed to Install in the Criticality Experiments Facility at the Nevada Test Site

    OpenAIRE

    Kim, S.; Heinrichs, D; Biswas, D.; Huang, S.; G. Dulik; J. Scorby; Boussoufi, M.; B. Liu; Wilson, R.

    2009-01-01

    Neutron detectors and control panels transferred from Rocky Flats Plant (RFP) were recalibrated and retested for redeployment to the CEF. Testing and calibration were successful with no failure to any equipment. Detector sensitivity was tested at the TRIGA reactor, and the response to thermal neutron flux was satisfactory. MCNP calculated minimum fission yield (~ 2 × 1015 fissions) was applied to determine the thermal flux at selected detector positions at the CEF. Thermal flux levels were...

  7. Transmutation detectors

    Czech Academy of Sciences Publication Activity Database

    Viererbl, L.; Lahodová, Z.; Klupák, V.; Sus, F.; Kučera, Jan; Kůs, P.; Marek, M.

    2011-01-01

    Roč. 632, č. 1 (2011), s. 109-111. ISSN 0168-9002 Institutional research plan: CEZ:AV0Z10480505 Keywords : Transmutation detector * Activation method * Neutron detector * Neutron fluence Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.207, year: 2011

  8. Gaseous detectors

    CERN Document Server

    Fischer, Hans Gerhard

    1996-01-01

    Detector physics and operational aspects of gaseous detectors will be discussed. Topics such as ionization processes, gas amplification and its limitations, pulse formation and decoupling, related electronics constraints, operational stability and ageing phenomena will be touched with the aim at some quantitative understanding.

  9. Metal Detectors.

    Science.gov (United States)

    Harrington-Lueker, Donna

    1992-01-01

    Schools that count on metal detectors to stem the flow of weapons into the schools create a false sense of security. Recommendations include investing in personnel rather than hardware, cultivating the confidence of law-abiding students, and enforcing discipline. Metal detectors can be quite effective at afterschool events. (MLF)

  10. Focal Rigidity of Flat Tori

    CERN Document Server

    Kwakkel, Ferry; Peixoto, Mauricio

    2011-01-01

    Given a closed Riemannian manifold (M, g), there is a partition \\Sigma_i of its tangent bundle TM called the focal decomposition. The sets \\Sigma_i are closely associated to focusing of geodesics of (M, g), i.e. to the situation where there are exactly i geodesic arcs of the same length joining points p and q in M. In this note, we study the topological structure of the focal decomposition of a closed Riemannian manifold and its relation with the metric structure of the manifold. Our main result is that the flat n-tori are focally rigid, in the sense that if two flat tori are focally equivalent, then the tori are isometric up to rescaling.

  11. 49 CFR 231.6 - Flat cars.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Flat cars. 231.6 Section 231.6 Transportation... TRANSPORTATION RAILROAD SAFETY APPLIANCE STANDARDS § 231.6 Flat cars. (Cars with sides 12 inches or less above the floor may be equipped the same as flat cars.) (a) Hand brakes—(1) Number. Same as specified...

  12. Measurement the concentration of radon in the flats of Pristina, Kosovo polja and their surroundings

    International Nuclear Information System (INIS)

    By using the solid state track detectors is made the measurements of the radon concentration in the flats on the Pristina area and its closed surroundings. The concentration of the radon was under 150 Bq/m3 but in the same places its amount is between 150 Bq/m3 and 750 Bq/m3. (author)

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  15. New detectors technology for radiology imaging

    International Nuclear Information System (INIS)

    We summarize the main parameters which describes the radiological image at first and the advantages of pixel detectors. All detectors converts X-rays in charges either with an intermediate step with light or directly in a semi-conductor media. That is true for tomography which is the first domain where digital processing have been taken in account and for radiology where flat panel are now proposed to radiologists. Nevertheless, luminescent stimulated screens are a good way to prepare users with digital radiography. As such technique is not valuable for dynamic acquisition, we describe systems which used standard luminescent screens with CCD cameras or with IIR. Some description and comparison of flat panel independent pixel detectors are given. (authors)

  16. MS Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Koppenaal, David W.; Barinaga, Charles J.; Denton, M Bonner B.; Sperline, Roger P.; Hieftje, Gary M.; Schilling, G. D.; Andrade, Francisco J.; Barnes IV., James H.

    2005-11-01

    Good eyesight is often taken for granted, a situation that everyone appreciates once vision begins to fade with age. New eyeglasses or contact lenses are traditional ways to improve vision, but recent new technology, i.e. LASIK laser eye surgery, provides a new and exciting means for marked vision restoration and improvement. In mass spectrometry, detectors are the 'eyes' of the MS instrument. These 'eyes' have also been taken for granted. New detectors and new technologies are likewise needed to correct, improve, and extend ion detection and hence, our 'chemical vision'. The purpose of this report is to review and assess current MS detector technology and to provide a glimpse towards future detector technologies. It is hoped that the report will also serve to motivate interest, prompt ideas, and inspire new visions for ion detection research.

  17. Flat lens for seismic waves

    CERN Document Server

    Brule, Stephane; Guenneau, Sebastien

    2016-01-01

    A prerequisite for achieving seismic invisibility is to demonstrate the ability of civil engineers to control seismic waves with artificially structured soils. We carry out large-scale field tests with a structured soil made of a grid consisting of cylindrical and vertical holes in the ground and a low frequency artificial source (< 10 Hz). This allows the identification of a distribution of energy inside the grid, which can be interpreted as the consequence of an effective negative refraction index. Such a flat lens reminiscent of what Veselago and Pendry envisioned for light opens avenues in seismic metamaterials to counteract the most devastating components of seismic signals.

  18. Reflections on a flat wall

    International Nuclear Information System (INIS)

    This paper describes an investigation into whether estimates of attenuation in the flat sidewalls of the tunnel for the MC main ring can be based on a simple point-source/line-of-sight model. Having seen the limitations of such a model, an alternative is proposed where the main radiation source is not the initial object struck by the beam but the plane source provided by the first interactions of secondaries from the target in the shield-wall. This is shown to have a closer relation to reality than the point-source/line-of-sight model. (author)

  19. Abrasion of flat rotating shapes

    OpenAIRE

    Roth, A.E.; Marques, C. M.; Durian, D. J.

    2010-01-01

    We report on the erosion of flat linoleum "pebbles" under steady rotation in a slurry of abrasive grit. To quantify shape as a function of time, we develop a general method in which the pebble is photographed from multiple angles with respect to the grid of pixels in a digital camera. This reduces digitization noise, and allows the local curvature of the contour to be computed with a controllable degree of uncertainty. Several shape descriptors are then employed to follow the evolution of dif...

  20. Photon detectors

    International Nuclear Information System (INIS)

    J. Seguinot and T. Ypsilantis have recently described the theory and history of Ring Imaging Cherenkov (RICH) detectors. In this paper, I will expand on these excellent review papers, by covering the various photon detector designs in greater detail, and by including discussion of mistakes made, and detector problems encountered, along the way. Photon detectors are among the most difficult devices used in physics experiments, because they must achieve high efficiency for photon transport and for the detection of single photo-electrons. For gaseous devices, this requires the correct choice of gas gain in order to prevent breakdown and wire aging, together with the use of low noise electronics having the maximum possible amplification. In addition, the detector must be constructed of materials which resist corrosion due to photosensitive materials such as, the detector enclosure must be tightly sealed in order to prevent oxygen leaks, etc. The most critical step is the selection of the photocathode material. Typically, a choice must be made between a solid (CsI) or gaseous photocathode (TMAE, TEA). A conservative approach favors a gaseous photocathode, since it is continuously being replaced by flushing, and permits the photon detectors to be easily serviced (the air sensitive photocathode can be removed at any time). In addition, it can be argued that we now know how to handle TMAE, which, as is generally accepted, is the best photocathode material available as far as quantum efficiency is concerned. However, it is a very fragile molecule, and therefore its use may result in relatively fast wire aging. A possible alternative is TEA, which, in the early days, was rejected because it requires expensive CaF2 windows, which could be contaminated easily in the region of 8.3 eV and thus lose their UV transmission

  1. Photon detectors

    Energy Technology Data Exchange (ETDEWEB)

    Va`vra, J.

    1995-10-01

    J. Seguinot and T. Ypsilantis have recently described the theory and history of Ring Imaging Cherenkov (RICH) detectors. In this paper, I will expand on these excellent review papers, by covering the various photon detector designs in greater detail, and by including discussion of mistakes made, and detector problems encountered, along the way. Photon detectors are among the most difficult devices used in physics experiments, because they must achieve high efficiency for photon transport and for the detection of single photo-electrons. For gaseous devices, this requires the correct choice of gas gain in order to prevent breakdown and wire aging, together with the use of low noise electronics having the maximum possible amplification. In addition, the detector must be constructed of materials which resist corrosion due to photosensitive materials such as, the detector enclosure must be tightly sealed in order to prevent oxygen leaks, etc. The most critical step is the selection of the photocathode material. Typically, a choice must be made between a solid (CsI) or gaseous photocathode (TMAE, TEA). A conservative approach favors a gaseous photocathode, since it is continuously being replaced by flushing, and permits the photon detectors to be easily serviced (the air sensitive photocathode can be removed at any time). In addition, it can be argued that we now know how to handle TMAE, which, as is generally accepted, is the best photocathode material available as far as quantum efficiency is concerned. However, it is a very fragile molecule, and therefore its use may result in relatively fast wire aging. A possible alternative is TEA, which, in the early days, was rejected because it requires expensive CaF{sub 2} windows, which could be contaminated easily in the region of 8.3 eV and thus lose their UV transmission.

  2. National construction, Denmark. Flat roofs

    Energy Technology Data Exchange (ETDEWEB)

    Rode, C.

    1995-04-01

    The Paris meeting of IEA Annex 24 (held in the spring of 1991) declared a set of typical building constructions, the Heat, Air and Moisture characteristics of which should be dealt with as part of the Annex work. Each type of construction was assigned to one or more countries as their National Construction, and it has been the responsibility of each country to prepare a report on what may be regarded as common knowledge in the country on the hygrothermal behaviour of their construction. This knowledge is in part due to experimental work carried out by research bodies in the countries, and due to experience form practice. This report has two main sections: Section 2 gives a general overview of the design of the most common variants of flat roofs and common knowledge reported for such roofs. Section 3 gives an account of research projects carried out in Denmark on flat roofs to analyze their hygrothermal performance. Whenever possible, an emphasis will be put on the hygrothermal consequences of thermally insulating such constructions. (EG) 19 refs.

  3. C臂CT在肝癌诊断与介入治疗中的应用现状%Application Status of C-arm Computed Tomography in the Diagnosis and Interventional Treatment of Liver Cancer

    Institute of Scientific and Technical Information of China (English)

    郝伟远

    2011-01-01

    @@ C臂CT(C-arm computed tomography)成像技术是西门子医疗系统集团近年新推出的利用C型臂血管造影系统进行三维容积CT成像的新技术(DynaCT).不同品牌的平板血管机C臂CT成像功能名称不一样,如: 西门子数字减影血管造影系统(Dyna CT)、飞利浦数字减影血管造影系统(Xper CT)和通用数字减影血管造影系统(Innova CT) 等.

  4. Calorimeter detectors

    CERN Document Server

    de Barbaro, P; The ATLAS collaboration

    2013-01-01

    Although the instantaneous and integrated luminosity in HL-LHC will be far higher than the LHC detectors were originally designed for, the Barrel calorimeters of the four experiments are expected to continue to perform well  throughout the Phase II program. The conditions for the End-Cap calorimeters are far more challenging and whilst some detectors will require relatively modest changes, others require far more substantial upgrades. We present the results of longevity and performance studies for the calorimeter systems of the four main LHC experiments and outline the upgrade options under consideration. We include a discussion of the R&D required to make the final technology choices for the upgraded detectors.

  5. Pixel detectors

    CERN Document Server

    Passmore, M S

    2001-01-01

    positions on the detector. The loss of secondary electrons follows the profile of the detector and increases with higher energy ions. studies of the spatial resolution predict a value of 5.3 lp/mm. The image noise in photon counting systems is investigated theoretically and experimentally and is shown to be given by Poisson statistics. The rate capability of the LAD1 was measured to be 250 kHz per pixel. Theoretical and experimental studies of the difference in contrast for ideal charge integrating and photon counting imaging systems were carried out. It is shown that the contrast differs and that for the conventional definition (contrast = (background - signal)/background) the photon counting device will, in some cases, always give a better contrast than the integrating system. Simulations in MEDICI are combined with analytical calculations to investigate charge collection efficiencies (CCE) in semiconductor detectors. Different pixel sizes and biasing conditions are considered. The results show charge shari...

  6. MAMA Detector

    Science.gov (United States)

    Bowyer, Stuart

    1998-01-01

    Work carried out under this grant led to fundamental discoveries and over one hundred publications in the scientific literature. Fundamental developments in instrumentation were made including all the instrumentation on the EUVE satellite, the invention of a whole new type of grazing instrument spectrometer and the development of fundamentally new photon counting detectors including the Wedge and Strip used on EUVE and many other missions and the Time Delay detector used on OREFUS and FUSE. The Wedge and Strip and Time Delay detectors were developed under this grant for less than two million dollars and have been used in numerous missions most recently for the FUSE mission. In addition, a fundamentally new type of diffuse spectrometer has been developed under this grant which has been used in instrumentation on the MMSAT spacecraft and the Lewis spacecraft. Plans are underway to use this instrumentation on several other missions as well.

  7. Ionization detector

    International Nuclear Information System (INIS)

    The objects of the invention are, first, to provide an ionization detector having a three chamber structure characterised by a built-in feedback path that regeneratively stabilizes the operating point of the detector. Secondly, to provide a specially designed chamber construction including electrodes shaped so as to enhance the efficiency of the chamber and reduce ion recombination. The ionization chamber described has a chamber structure with a first closed chamber and a second chamber able to receive gases from outside. These two chambers have a common boundary including a common electrode. One electrode associated with the second chamber, and one within the first chamber, define a third chamber within the first chamber allowing an ionization path between. A radioactive source provides ionizing radiation for all three chambers and establishes an ionization current. There is a detector coupled to the common electrode for detecting changes in this current. (U.K.)

  8. BES detector

    International Nuclear Information System (INIS)

    The Beijing Spectrometer (BES) is a general purpose solenoidal detector at the Beijing Electron Positron Collider (BEPC). It is designed to study exclusive final states in e+e- annihilations at the center of mass energy from 3.0 to 5.6 GeV. This requires large solid angle coverage combined with good charged particle momentum resolution, good particle identification and high photon detection efficiency at low energies. In this paper we describe the construction and the performance of BES detector. (orig.)

  9. "Flat-Fish" Vacuum Chamber

    CERN Multimedia

    1978-01-01

    The picture shows a "Flat-Fish" vacuum chamber being prepared in the ISR workshop for testing prior to installation in the Split Field Magnet (SFM) at intersection I4. The two shells of each part were hydroformed from 0.15 mm thick inconel 718 sheet (with end parts in inconel 600 for easier manual welding to the arms) and welded toghether with two strips which were attached by means of thin stainless steel sheets to the Split Field Magnet poles in order to take the vertical component of the atmospheric pressure force. This was the thinnest vacuum chamber ever made for the ISR. Inconel material was chosen for its high elastic modulus and strenght at chamber bake-out temperature. In this picture the thin sheets transferring the vertical component of the atmosferic pressure force are attached to a support frame for testing. See also 7712182, 7712179.

  10. Flat bunches in the LHC

    CERN Document Server

    Shaposhnikova, E; Baudrenghien, P; Mastoridis, T; Muller, J E; Papotti, G; Salvant, B; Timko, H; Bhat, C; Burov, A

    2014-01-01

    A high harmonic RF system which could serve multiple purposes was proposed for the LHC. Possible applications of the second harmonic RF system include beam stabilisation in the longitudinal plane in absence of wide-band longitudinal feedback and reduction of bunch peak line density. Apart from other useful features flat bunches are expected to produce less beam-induced heating below 1 GHz, the frequency region critical for some LHC equipment. The latter however can also be achieved by de-populating the bunch center. This was demonstrated during the dedicated machine development session in the LHC using RF phase modulation. In this paper the results of tests with single bunches and nominal LHC beams are presented and possible use of this technique in LHC operation is discussed.

  11. Flat laminated microbial mat communities

    Science.gov (United States)

    Franks, Jonathan; Stolz, John F.

    2009-10-01

    Flat laminated microbial mats are complex microbial ecosystems that inhabit a wide range of environments (e.g., caves, iron springs, thermal springs and pools, salt marshes, hypersaline ponds and lagoons, methane and petroleum seeps, sea mounts, deep sea vents, arctic dry valleys). Their community structure is defined by physical (e.g., light quantity and quality, temperature, density and pressure) and chemical (e.g., oxygen, oxidation/reduction potential, salinity, pH, available electron acceptors and donors, chemical species) parameters as well as species interactions. The main primary producers may be photoautotrophs (e.g., cyanobacteria, purple phototrophs, green phototrophs) or chemolithoautophs (e.g., colorless sulfur oxidizing bacteria). Anaerobic phototrophy may predominate in organic rich environments that support high rates of respiration. These communities are dynamic systems exhibiting both spatial and temporal heterogeneity. They are characterized by steep gradients with microenvironments on the submillimeter scale. Diel oscillations in the physical-chemical profile (e.g., oxygen, hydrogen sulfide, pH) and species distribution are typical for phototroph-dominated communities. Flat laminated microbial mats are often sites of robust biogeochemical cycling. In addition to well-established modes of metabolism for phototrophy (oxygenic and non-oxygenic), respiration (both aerobic and anaerobic), and fermentation, novel energetic pathways have been discovered (e.g., nitrate reduction couple to the oxidation of ammonia, sulfur, or arsenite). The application of culture-independent techniques (e.g., 16S rRNA clonal libraries, metagenomics), continue to expand our understanding of species composition and metabolic functions of these complex ecosystems.

  12. Representability of Hom Implies Flatness

    Indian Academy of Sciences (India)

    Nitin Nitsure

    2004-02-01

    Let be a projective scheme over a noetherian base scheme , and let $\\mathcal{F}$ be a coherent sheaf on . For any coherent sheaf $\\mathcal{E}$ on , consider the set-valued contravariant functor $\\hom_{(\\mathcal{E},\\mathcal{F})}$ on -schemes, defined by $\\hom_{(\\mathcal{E},\\mathcal{F})}(T)=\\mathrm{Hom}(\\mathcal{E}_T,\\mathcal{F}_T)$ where $\\mathcal{E}_T$ and $\\mathcal{F}_T$ are the pull-backs of $\\mathcal{E}$ and $\\mathcal{F}$ to $X_T=X×_s T$. A basic result of Grothendieck ([EGA], III 7.7.9) says that if $\\mathcal{F}$ is flat over then $\\hom_{(\\mathcal{E},\\mathcal{F})}$ is representable for all $\\mathcal{E}$. We prove the converse of the above, in fact, we show that if is a relatively ample line bundle on over such that the functor $\\hom_{(L^{-n},\\mathcal{F})}$ is representable for infinitely many positive integers , then $\\mathcal{F}$ is flat over . As a corollary, taking $X=S$, it follows that if $\\mathcal{F}$ is a coherent sheaf on then the functor $T\\mapsto H^0(T,\\mathcal{F}_T)$ on the category of -schemes is representable if and only if $\\mathcal{F}$ is locally free on . This answers a question posed by Angelo Vistoli. The techniques we use involve the proof of flattening stratification, together with the methods used in proving the author's earlier result (see [N1]) that the automorphism group functor of a coherent sheaf on is representable if and only if the sheaf is locally free.

  13. Gravitating cosmic strings with flat directions

    OpenAIRE

    Hartmann, Betti; Lopez-Eiguren, Asier; Sousa, Kepa; Urrestilla, Jon

    2012-01-01

    We study field theoretical models for cosmic strings with flat directions in curved space-time. More precisely, we consider minimal models with semilocal, axionic and tachyonic strings, respectively. In flat space-time, the string solutions of these models have a flat direction, i.e., a uniparametric family of configurations with the same energy exists which is associated to a zero mode. We prove that the zero mode survives coupling to gravity, and study the role of the flat direction when co...

  14. Flat-band engineering of mobility edges

    Science.gov (United States)

    Danieli, Carlo; Bodyfelt, Joshua D.; Flach, Sergej

    2015-06-01

    Properly modulated flat-band lattices have a divergent density of states at the flat-band energy. Quasiperiodic modulations are known to host a metal-insulator transition already in one space dimension. Their embedding into flat-band geometries consequently allows for a precise engineering and fine tuning of mobility edges. We obtain analytic expressions for singular mobility edges for two flat-band lattice examples. In particular, we engineer cases with arbitrarily small energy separations of mobility edge, zeroes, and divergencies.

  15. Flat conductor cable design, manufacture, and installation

    Science.gov (United States)

    Angele, W.; Hankins, J. D.

    1973-01-01

    Pertinent information for hardware selection, design, manufacture, and quality control necessary for flat conductor cable interconnecting harness application is presented. Comparisons are made between round wire cable and flat conductor cable. The flat conductor cable interconnecting harness systems show major cost, weight, and space savings, plus increased system performance and reliability. The design application section includes electrical characteristics, harness design and development, and a full treatise on EMC considerations. Manufacturing and quality control sections pertain primarily to the developed conductor-contact connector system and special flat conductor cable to round wire cable transitions.

  16. A flat array large telescope concept for use on the moon, earth, and in space

    Science.gov (United States)

    Woodgate, Bruce E.

    1991-01-01

    An astronomical optical telescope concept is described which can provide very large collecting areas, of order 1000 sq m. This is an order of magnitude larger than the new generation of telescopes now being designed and built. Multiple gimballed flat mirrors direct the beams from a celestial source into a single telescope of the same aperture as each flat mirror. Multiple images of the same source are formed at the telescope focal plane. A beam combiner collects these images and superimposes them into a single image, onto a detector or spectrograph aperture. This telescope could be used on the earth, the moon, or in space.

  17. Detector light response modeling for a thick continuous slab detector

    International Nuclear Information System (INIS)

    We investigate a method to improve the position decoding for thick crystal versions (i.e., ≥8mm) of the continuous miniature crystal element (cMiCE) PET detector by more accurately modeling the detector light response function (LRF). The LRF for continuous detectors varies with the depth of interaction (DOI) of the detected photon. This variation in LRF can result in a positioning error for two-dimensional positioning algorithms. We explore a method to improve positioning performance by deriving two lookup tables, corresponding to the front and back regions of the crystal. The DETECT2000 simulation package was used to investigate the light response characteristics for a 48.8 mm by 48.8 mm by 10 (8) mm slab of LSO coupled to a 64-channel, flat-panel PMT. The data are then combined to produce the two-dimensional light collection histograms. Light collection histograms that have markedly non-Gaussian distributions are characterized as a combination of two Gaussian functions, where each Gaussian function corresponds to a DOI region of the crystal. The results indicate that modest gains in positioning accuracy are achieved near the central region of the crystal. However, significant improvements in spatial resolution and positioning bias are achieved for the corner section of the detector. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.)

  19. Artifacts Found During Quality Assurance Testing of Computed Radiography and Digital Radiography Detectors

    OpenAIRE

    Honey, Ian D.; MacKenzie, Alistair

    2008-01-01

    A series of artifact images, obtained over 5 years of performance testing, of both computed radiography (CR) and integrated digital radiographic X-ray imaging detectors are presented. The images presented are all either flat field or test object images and show artifacts previously either undescribed in the existing literature or meriting further comment. The artifacts described are caused by incorrect flat field corrections, a failing amplifier, damaged detector lines affecting their neighbo...

  20. Natural convection between flat parallel plates

    International Nuclear Information System (INIS)

    The rate of heat transfer between two flat parallel plates inclined at some angle to the horizone is of abvious important in performance of the flat plat collectors. A complete computer program have been made for calculating free convection heat transfer coefficient, h. Angle plays as an important parameter for determining Nusselt values for plate spacing more than 5mm.(Author)

  1. Radiation monitor training program at Rocky Flats

    International Nuclear Information System (INIS)

    The Rocky Flats Radiation Monitor Training Program is tailored to train new health physics personnel in the field of radiation monitoring. The purpose of the prescribed materials and media is to be consistent in training in all areas of Rocky Flats radiation monitoring job involvement

  2. Neutron detector

    Science.gov (United States)

    Stephan, Andrew C.; Jardret; Vincent D.

    2011-04-05

    A neutron detector has a volume of neutron moderating material and a plurality of individual neutron sensing elements dispersed at selected locations throughout the moderator, and particularly arranged so that some of the detecting elements are closer to the surface of the moderator assembly and others are more deeply embedded. The arrangement captures some thermalized neutrons that might otherwise be scattered away from a single, centrally located detector element. Different geometrical arrangements may be used while preserving its fundamental characteristics. Different types of neutron sensing elements may be used, which may operate on any of a number of physical principles to perform the function of sensing a neutron, either by a capture or a scattering reaction, and converting that reaction to a detectable signal. High detection efficiency, an ability to acquire spectral information, and directional sensitivity may be obtained.

  3. Particle detectors

    CERN Document Server

    Joram, Christian

    1998-01-01

    The lecture series will present and overview of the basic techniques and underlying physical principles of particle detectors, applied to current and future high energy physics experiments. Illustrating examples, mainly from the field of collider experiments, will demonstrate the performance and limitations of the various techniques. After and introduction we shall concentrate on particle tracking. Wire chambers, drift chambers, micro gaseous tracking devices and solid state trackers will be discussed. It follows and overview of scintillators, photon detection, fiber tracking and nuclear emulsions. One lecture will deal with the various techniques of calorimetry. Finally we shall focus on methods developed for particle identification. These comprise specific energy loss, time of flight Cherenkov and transition radiation detectors.

  4. The preamplifier design for CZT frisch detector

    International Nuclear Information System (INIS)

    CZT Frisch capacitance device uses two flat electrode connecting the cathode side of metal layer and connected, and insulating layer between the isolation. According to Frisch capacitance detector structure and the parameters of pre-amplifier, ac coupling was used. The depletion of high transconductance FET as the input stage, the composition of a capacitor and resistance as the feedback of the charge sensitive preamplifier were selected. The results show the design and manufacture of low noise, high-performance of the pre-amplifier for CZT Frisch detector is successful. Finally, the test results were given. (authors)

  5. Mobile C-arm X-ray image-splicing techniques applied in orthopedic surgery%移动式C型臂X射线机图像拼接在骨科手术中的应用*****

    Institute of Scientific and Technical Information of China (English)

    谢加兵; 徐祝军; 丁国正; 周茂生; 汪正宇; 朱劲松; 杨民

    2013-01-01

      背景:在脊柱和长骨骨折等骨科手术治疗中,获取骨折部位的完整骨结构图像对于监控和评价骨科术中效果具有十分重要的临床意义。  目的:探讨移动式C型臂X射线机图像拼接技术在临床骨科手术中的应用效果。  方法:对骨科手术部位的脊柱和长骨进行C型臂X射线机透视并采集2-4幅图像,经过图像拼接软件将图像多区域重叠,进行图像拼接技术处理后得到脊柱和长骨骨折内固定手术部位的1张全景图像。  结果与结论:移动式C型臂X射线机图像拼接技术处理后能在1张照片上获得脊柱和长骨骨折内固定手术部位全景图像,能较清晰、完整地显示脊柱和长骨的全景,并有助于术者在术中及时地了解和评估骨折部位的对位、对线情况,且能进行长度和角度测量,为进一步提高手术质量提供强有力的支持。%BACKGROUND:In the treatment of orthopedic surgery of the spine and long bone fractures, obtaining the complete bone structure image of the fracture part has great clinical significance for monitoring and evaluating the intraoperative effect of orthopedic surgery. OBJECTIVE:To investigate the clinical application of mobile C-arm X-ray image-splicing technology in orthopedic surgery. METHODS:The spine and long bone in the surgical site took the X-ray C-arm fluoroscopy in order to obtain 2-4 images. The image mosaicing software was used to multiple regional overlap the images, and then a panoramic image of spine and long bone on the surgical site was obtained after treated with image-splicing technology. RESULTS AND CONCLUSION:A panoramic image of spine and long bone on the surgical site was obtained on one photo after treated with C-arm X-ray image-splicing technology, which could display the overal view of spine and long bone clearly and completely, help the surgeon to understand and evaluate the contraposition and alignment

  6. WE-G-18A-01: JUNIOR INVESTIGATOR WINNER - Low-Dose C-Arm Cone-Beam CT with Model-Based Image Reconstruction for High-Quality Guidance of Neurosurgical Intervention

    International Nuclear Information System (INIS)

    Purpose: To address the challenges of image quality, radiation dose, and reconstruction speed in intraoperative cone-beam CT (CBCT) for neurosurgery by combining model-based image reconstruction (MBIR) with accelerated algorithmic and computational methods. Methods: Preclinical studies involved a mobile C-arm for CBCT imaging of two anthropomorphic head phantoms that included simulated imaging targets (ventricles, soft-tissue structures/bleeds) and neurosurgical procedures (deep brain stimulation (DBS) electrode insertion) for assessment of image quality. The penalized likelihood (PL) framework was used for MBIR, incorporating a statistical model with image regularization via an edgepreserving penalty. To accelerate PL reconstruction, the ordered-subset, separable quadratic surrogates (OS-SQS) algorithm was modified to incorporate Nesterov's method and implemented on a multi-GPU system. A fair comparison of image quality between PL and conventional filtered backprojection (FBP) was performed by selecting reconstruction parameters that provided matched low-contrast spatial resolution. Results: CBCT images of the head phantoms demonstrated that PL reconstruction improved image quality (∼28% higher CNR) even at half the radiation dose (3.3 mGy) compared to FBP. A combination of Nesterov's method and fast projectors yielded a PL reconstruction run-time of 251 sec (cf., 5729 sec for OS-SQS, 13 sec for FBP). Insertion of a DBS electrode resulted in severe metal artifact streaks in FBP reconstructions, whereas PL was intrinsically robust against metal artifact. The combination of noise and artifact was reduced from 32.2 HU in FBP to 9.5 HU in PL, thereby providing better assessment of device placement and potential complications. Conclusion: The methods can be applied to intraoperative CBCT for guidance and verification of neurosurgical procedures (DBS electrode insertion, biopsy, tumor resection) and detection of complications (intracranial hemorrhage

  7. WE-G-18A-01: JUNIOR INVESTIGATOR WINNER - Low-Dose C-Arm Cone-Beam CT with Model-Based Image Reconstruction for High-Quality Guidance of Neurosurgical Intervention

    Energy Technology Data Exchange (ETDEWEB)

    Wang, A; Stayman, J; Otake, Y; Gallia, G; Siewerdsen, J [Johns Hopkins University, Baltimore, MD (United States)

    2014-06-15

    Purpose: To address the challenges of image quality, radiation dose, and reconstruction speed in intraoperative cone-beam CT (CBCT) for neurosurgery by combining model-based image reconstruction (MBIR) with accelerated algorithmic and computational methods. Methods: Preclinical studies involved a mobile C-arm for CBCT imaging of two anthropomorphic head phantoms that included simulated imaging targets (ventricles, soft-tissue structures/bleeds) and neurosurgical procedures (deep brain stimulation (DBS) electrode insertion) for assessment of image quality. The penalized likelihood (PL) framework was used for MBIR, incorporating a statistical model with image regularization via an edgepreserving penalty. To accelerate PL reconstruction, the ordered-subset, separable quadratic surrogates (OS-SQS) algorithm was modified to incorporate Nesterov's method and implemented on a multi-GPU system. A fair comparison of image quality between PL and conventional filtered backprojection (FBP) was performed by selecting reconstruction parameters that provided matched low-contrast spatial resolution. Results: CBCT images of the head phantoms demonstrated that PL reconstruction improved image quality (∼28% higher CNR) even at half the radiation dose (3.3 mGy) compared to FBP. A combination of Nesterov's method and fast projectors yielded a PL reconstruction run-time of 251 sec (cf., 5729 sec for OS-SQS, 13 sec for FBP). Insertion of a DBS electrode resulted in severe metal artifact streaks in FBP reconstructions, whereas PL was intrinsically robust against metal artifact. The combination of noise and artifact was reduced from 32.2 HU in FBP to 9.5 HU in PL, thereby providing better assessment of device placement and potential complications. Conclusion: The methods can be applied to intraoperative CBCT for guidance and verification of neurosurgical procedures (DBS electrode insertion, biopsy, tumor resection) and detection of complications (intracranial hemorrhage

  8. Design of geometrical detector arrangement for extensive holdup measurement

    International Nuclear Information System (INIS)

    In the Plutonium Conversion Development Facility (PCDF) of Japan Nuclear Cycle Development Institute (JNC), an improved holdup measurement system has been developed with flat response profile for the blending glove box (GB). The geometrical detector arrangement was optimized based on the numerical calculation of solid angle subtended by the detectors. The detector setting up procedure was simplified and the detector movement was manipulated by remote control. As a result, we have achieved the flatness within 10% deviation of the response profile in the region of the GB where holdup might remain and reduced operator's exposure by half. Subsequently, the new system was calibrated using MOX standards and the good calibration equations were obtained. We concluded that the performance of the new system was sufficient for our purposes. (author)

  9. Long-range Rocky Flats utilization study

    International Nuclear Information System (INIS)

    The purpose of this Study was to provide information concerning the Rocky Flats Plant and its operations that will be useful to the Nation's decision-makers in determining the long-range future of the Plant. This Study was conducted under the premise that national defense policy must be supported and, accordingly, the capabilities at Rocky Flats must be maintained there or at some other location(s). The Study, therefore, makes no attempt to speculate on how possible future changes in national defense policy might affect decisions regarding the utilization of Rocky Flats. Factors pertinent to decisions regarding Rocky Flats, which are included in the Study, are: physical condition of the Plant and its vulnerabilities to natural phenomena; risks associated with plutonium to Plant workers and the public posed by postulated natural phenomena and operational accidents; identification of alternative actions regarding the future use of the Rocky Flats Plant with associated costs and time scales; local socioeconomic impacts if Rocky Flats operations were relocated; and potential for other uses if Rocky Flats facilities were vacated. The results of the tasks performed in support of this Study are summarized in the context of these five factors

  10. Measuring module of the Cherenkov water detector NEVOD

    Science.gov (United States)

    Kindin, V. V.; Amelchakov, M. B.; Barbashina, N. S.; Bogdanov, A. G.; Burtsev, V. D.; Chernov, D. V.; Khokhlov, S. S.; Khomyakov, V. A.; Kokoulin, R. P.; Kompaniets, K. G.; Kovylyaeva, E. A.; Kruglikova, V. S.; Ovchinnikov, V. V.; Petrukhin, A. A.; Shulzhenko, I. A.; Shutenko, V. V.; Yashin, I. I.; Zadeba, E. A.

    2015-08-01

    Quasispherical Module (QSM) of Cherenkov water detector NEVOD represents six low-noise FEU-200 photomultipliers with flat photocathodes (15 cm in diameter), oriented along the axes of orthogonal coordinate system. Such configuration allows to register Cherenkov radiation arriving from any direction with almost equal efficiency. The results of measurements of QSM characteristics in the sensitive volume of the NEVOD detector during the registration of Cherenkov radiation of single muons at different distances and angles are discussed.

  11. AdS/Ricci-flat correspondence

    International Nuclear Information System (INIS)

    We present a comprehensive analysis of the AdS/Ricci-flat correspondence, a map between a class of asymptotically locally AdS spacetimes and a class of Ricci-flat spacetimes. We provide a detailed derivation of the map, discuss a number of extensions and apply it to a number of important examples, such as AdS on a torus, AdS black branes and fluids/gravity metrics. In particular, the correspondence links the hydrodynamic regime of asymptotically flat black p-branes or the Rindler fluid with that of AdS. It implies that this class of Ricci-flat spacetimes inherits from AdS a generalized conformal symmetry and has a holographic structure. We initiate the discussion of holography by analyzing how the map acts on boundary conditions and holographic 2-point functions

  12. Fuzzy Neural Model for Flatness Pattern Recognition

    Institute of Scientific and Technical Information of China (English)

    JIA Chun-yu; SHAN Xiu-ying; LIU Hong-min; NIU Zhao-ping

    2008-01-01

    For the problems occurring in a least square method model,a fuzzy model,and a neural network model for flatness pattern recognition,a fuzzy neural network model for flatness pattern recognition with only three-input and three-output signals was proposed with Legendre orthodoxy polynomial as basic pattern,based on fuzzy logic expert experiential knowledge and genetic-BP hybrid optimization algorithm.The model not only had definite physical meanings in its inner nodes,but also had strong self-adaptability,anti-interference ability,high recognition precision,and high velocity,thereby meeting the demand of high-precision flatness control for cold strip mill and providing a convenient,practical,and novel method for flatness pattern recognition.

  13. AdS/Ricci-flat correspondence

    CERN Document Server

    Caldarelli, M M; Goutéraux, B; Skenderis, K

    2014-01-01

    We present a comprehensive analysis of the AdS/Ricci-flat correspondence, a map between a class of asymptotically locally AdS spacetimes and a class of Ricci-flat spacetimes. We provide a detailed derivation of the map, discuss a number of extensions and apply the map to a number of important examples, such as AdS on a torus, AdS black branes and fluids/gravity metrics. In particular, the map links the hydrodynamic regime of asymptotically flat black $p$-branes or the Rindler fluid with that of AdS. The map implies that this class of Ricci-flat spacetimes inherits from AdS a generalized conformal symmetry and has a holographic structure. We initiate the discussion of holography by analyzing how the map acts on boundary conditions and holographic 2-point functions.

  14. Flat-package DIP handling tool

    Science.gov (United States)

    Angelou, E.; Fraser, R.

    1977-01-01

    Device, using magnetic attraction, can facilitate handling of integrated-circuit flat packages and prevent contamination and bent leads. Tool lifts packages by their cases and releases them by operation of manual plunger.

  15. Post-Punching Behavior of Flat Slabs

    OpenAIRE

    Fernández Ruiz, Miguel; Mirzaei, Yaser; Muttoni, Aurelio

    2013-01-01

    Reinforced concrete flat slabs are a common structural system for cast-in-place concrete slabs. Failures in punching shear near the column regions are typically governing at ultimate. In case no punching shear or integrity reinforcement is placed, failures in punching develop normally in a brittle manner with almost no warning signs. Furthermore, the residual strength after punching is, in general, significantly lower than the punching load. Thus, punching of a single column of a flat slab ov...

  16. Flat Taxes and Effective Tax Planning

    OpenAIRE

    Calegari, Michael

    1998-01-01

    Stiglitz (1985) shows that income deferral opportunities and differentially taxed economic activities provide incentives for investors to engage in tax avoidance strategies. In this paper, I describe several tax avoidance strategies that can be used by taxpayers in a Hall-Rabushka flat tax system to reduce or eliminate their tax liabilities. Effective tax planning continues to be viable in a flat tax regime because the idealized environment envisioned by the proposal does not consider taxpaye...

  17. Loop Quantum Gravity and Asymptotically Flat Spaces

    OpenAIRE

    Arnsdorf, Matthias

    2000-01-01

    After motivating why the study of asymptotically flat spaces is important in loop quantum gravity, we review the extension of the standard framework of this theory to the asymptotically flat sector based on the GNS construction. In particular, we provide a general procedure for constructing new Hilbert spaces for loop quantum gravity on non-compact spatial manifolds. States in these Hilbert spaces can be interpreted as describing fluctuations around fiducial fixed backgrounds. When the backgr...

  18. Flat H Frangible Joint Evolution

    Science.gov (United States)

    Diegelman, Thomas E.; Hinkel, Todd J.; Benjamin, Andrew; Rochon, Brian V.; Brown, Christopher W.

    2016-01-01

    Space vehicle staging and separation events require pyrotechnic devices. They are single-use mechanisms that cannot be tested, nor can failure-tolerant performance be demonstrated in actual flight articles prior to flight use. This necessitates the implementation of a robust design and test approach coupled with a fully redundant, failure-tolerant explosive mechanism to ensure that the system functions even in the event of a single failure. Historically, NASA has followed the single failure-tolerant (SFT) design philosophy for all human-rated spacecraft, including the Space Shuttle Program. Following the end of this program, aerospace companies proposed building the next generation human-rated vehicles with off-the-shelf, non-redundant, zero-failure-tolerant (ZFT) separation systems. Currently, spacecraft and launch vehicle providers for both the Orion and Commercial Crew Programs (CCPs) plan to deviate from the heritage safety approach and NASA's SFT human rating requirements. Both programs' partners have base-lined ZFT frangible joints for vehicle staging and fairing separation. These joints are commercially available from pyrotechnic vendors. Non-human-rated missions have flown them numerous times. The joints are relatively easy to integrate structurally within the spacecraft. In addition, the separation event is debris free, and the resultant pyro shock is lower than that of other design solutions. It is, however, a serious deficiency to lack failure tolerance. When used for critical applications on human-rated vehicles, a single failure could potentially lead to loss of crew (LOC) or loss of mission (LOM)). The Engineering and Safety & Mission Assurance directorates within the NASA Johnson Space Center took action to address this safety issue by initiating a project to develop a fully redundant, SFT frangible joint design, known as the Flat H. Critical to the ability to retrofit on launch vehicles being developed, the SFT mechanisms must fit within the same

  19. Particle detectors

    CERN Document Server

    Hilke, Hans Jürgen; CERN. Geneva

    1991-01-01

    Lecture 5: Detector characteristics: ALEPH Experiment cut through the devices and events - Discuss the principles of the main techniques applied to particle detection ( including front-end electronics), the construction and performance of some of the devices presently in operartion and a few ideas on the future performance. Lecture 4-pt. b Following the Scintillators. Lecture 4-pt. a : Scintillators - Used for: -Timing (TOF, Trigger) - Energy Measurement (Calorimeters) - Tracking (Fibres) Basic scintillation processes- Inorganic Scintillators - Organic Scintil - Discuss the principles of the main techniques applied to particle detection ( including front-end electronics), the construction and performance of some of the devices presently in operation and a fiew ideas on future developpement session 3 - part. b Following Calorimeters lecture 3-pt. a Calorimeters - determine energy E by total absorption of charged or neutral particles - fraction of E is transformed into measurable quantities - try to acheive sig...

  20. Proximity focusing RICH detector based on multilayer silica aerogel radiator

    International Nuclear Information System (INIS)

    The performance of a proximity focusing Ring Imaging Cherenkov detector equipped with a radiator of silica aerogel is presented. The aerogel tile used is a monolith with variable index of refraction. Cherenkov photons are detected with high granularity by eight Hamamatsu H9500 flat panel multi anode phototubes.

  1. Proximity focusing RICH detector based on multilayer silica aerogel radiator

    CERN Document Server

    De Leo, R; Bellunato, T; Calvi, M; Cisbani, E; Cusanno, F; Garibaldi, F; Lagamba, L; Marra, M; Marrone, S; Matteuzzi, C; Musico, P; Nappi, E; Perego, D L; Torrioli, S; Vilardi, I

    2010-01-01

    The performance of a proximity focusing Ring Imaging Cherenkov detector equipped with a radiator of silica aerogel is presented. The aerogel tile used is a monolith with variable index of refraction. Cherenkov photons are detected with high granularity by eight Hamamatsu H9500 flat panel multi anode phototubes.

  2. A novel method for contrast-to-noise ratio (CNR) evaluation of digital mammography detectors

    Energy Technology Data Exchange (ETDEWEB)

    Baldelli, P.; Phelan, N.; Egan, G. [National Cancer Screening Service, Dublin (Ireland)

    2009-09-15

    The purpose of this study was to test a new, simple method of evaluating the contrast-to-noise ratio (CNR) over the entire image field of a digital detector and to compare different mammography systems. Images were taken under clinical exposure conditions for a range of simulated breast thicknesses using poly(methyl methacrylate) (PMMA). At each PMMA thickness, a second image which included an additional 0.2-mm Al sheet was also acquired. Image processing software was used to calculate the CNR in multiple regions of interest (ROI) covering the entire area of the detector in order to obtain a 'CNR image'. Five detector types were evaluated, two CsI-{alpha}Si (GE Healthcare) flat panel systems, one {alpha}Se (Hologic) flat panel system and a two generations of scanning photon counting digital detectors (Sectra). Flat panel detectors exhibit better CNR uniformity compared with the first-generation scanning photon counting detector in terms of mean pixel value variation. However, significant improvement in CNR uniformity was observed for the next-generation scanning detector. The method proposed produces a map of the CNR and a measurement of uniformity throughout the entire image field of the detector. The application of this method enables quality control measurement of individual detectors and a comparison of detectors using different technologies. (orig.)

  3. A novel method for contrast-to-noise ratio (CNR) evaluation of digital mammography detectors

    International Nuclear Information System (INIS)

    The purpose of this study was to test a new, simple method of evaluating the contrast-to-noise ratio (CNR) over the entire image field of a digital detector and to compare different mammography systems. Images were taken under clinical exposure conditions for a range of simulated breast thicknesses using poly(methyl methacrylate) (PMMA). At each PMMA thickness, a second image which included an additional 0.2-mm Al sheet was also acquired. Image processing software was used to calculate the CNR in multiple regions of interest (ROI) covering the entire area of the detector in order to obtain a 'CNR image'. Five detector types were evaluated, two CsI-αSi (GE Healthcare) flat panel systems, one αSe (Hologic) flat panel system and a two generations of scanning photon counting digital detectors (Sectra). Flat panel detectors exhibit better CNR uniformity compared with the first-generation scanning photon counting detector in terms of mean pixel value variation. However, significant improvement in CNR uniformity was observed for the next-generation scanning detector. The method proposed produces a map of the CNR and a measurement of uniformity throughout the entire image field of the detector. The application of this method enables quality control measurement of individual detectors and a comparison of detectors using different technologies. (orig.)

  4. Recent developments in digital radiography detectors

    Science.gov (United States)

    Yorkston, John

    2007-10-01

    Medical projection radiography is currently undergoing a major transformation into the digital age. New digital X-ray detectors are providing improved image quality as well as increased functionality. These advances promise to significantly change the practice of radiology in the coming years. This review paper will describe some of the issues associated with the new digital detectors, their design, capabilities and limitations as well as a few of the promising new clinical applications being enabled by their introduction. The review will focus mainly on the new amorphous silicon flat-panel detectors but will also touch on other technologies and promising new developments that may be introduced into the clinical environment in the not too distant future.

  5. Alignment of the NOMAD-STAR detector

    CERN Document Server

    Cervera-Villanueva, A

    2000-01-01

    This note describes the alignment of the NOMAD-STAR detector. This is the B/sub 4/C-silicon target installed in the NOMAD spectrometer in 1997. NOMAD-STAR is composed of modules of 12 silicon detectors each giving a total length of 72 cm. Ten of these modules (called ladders) are assembled to form a layer. There are five layers interleaved with passive boron carbide plates. The total surface of silicon is 1.14 m /sup 2/. Energetic muons from the flat-top of the CERN SPS cycle provide the necessary information to perform a very precise software alignment. This alignment is needed to ensure that the impact parameter measurement needed for the identification of taus in a detector like NOMAD-STAR will not be limited by the error in the alignment. (15 refs).

  6. Andean flat subduction maintained by slab tunneling

    Science.gov (United States)

    Schepers, Gerben; van Hinsbergen, Douwe; Kosters, Martha; Boschman, Lydian; McQuarrie, Nadine; Spakman, Wim

    2016-04-01

    In two segments below the Andean mountain belt, the Nazca Plate is currently subducting sub-horizontally below South America over a distance of 200-300 km before the plate bends into the mantle. Such flat slab segments have pronounced effects on orogenesis and magmatism and are widely believed to be caused by the downgoing plate resisting subduction due to its local positive buoyancy. In contrast, here we show that flat slabs primarily result from a local resistance against rollback rather than against subduction. From a kinematic reconstruction of the Andean fold-thrust belt we determine up to ~390 km of shortening since ~50 Ma. During this time the South American Plate moved ~1400 km westward relative to the mantle, thus forcing ~1000 km of trench retreat. Importantly, since the 11-12 Ma onset of flat slab formation, ~1000 km of Nazca Plate subduction occurred, much more than the flat slab lengths, which leads to our main finding that the flat slabs, while being initiated by arrival of buoyant material at the trench, are primarily maintained by locally impeded rollback. We suggest that dynamic support of flat subduction comes from the formation of slab tunnels below segments with the most buoyant material. These tunnels trap mantle material until tearing of the tunnel wall provides an escape route. Fast subduction of this tear is followed by a continuous slab and the process can recur during ongoing rollback of the 7000 km wide Nazca slab at segments with the most buoyant subducting material, explaining the regional and transient character of flat slabs. Our study highlights the importance of studying subduction dynamics in absolute plate motion context.

  7. Do intertidal flats ever reach equilibrium?

    Science.gov (United States)

    Maan, D. C.; Prooijen, B. C.; Wang, Z. B.; De Vriend, H. J.

    2015-11-01

    Various studies have identified a strong relation between the hydrodynamic forces and the equilibrium profile for intertidal flats. A thorough understanding of the interplay between the hydrodynamic forces and the morphology, however, concerns more than the equilibrium state alone. We study the basic processes and feedback mechanisms underlying the long-term behavior of the intertidal system, restricting ourselves to unvegetated intertidal flats that are controlled by cross-shore tidal currents and wind waves and applying a 1-D cross-shore morphodynamic model. The results indicate that by an adjustment of the profile slope and shape, an initial imbalance between deposition and erosion is minimized within a few decades. What follows is a state of long-term seaward progradation or landward retreat of the intertidal flat, in which the cross-shore profile shape is largely maintained and the imbalance between deposition and erosion is not further reduced. These long-term trends can be explained by positive feedbacks from the morphology onto the hydrodynamic forces over the flat: initial accretion (erosion) decreases (increases) the shear stresses over the flat, which induces further accretion (erosion). This implies that a static equilibrium state cannot exist; the flat either builds out or retreats. The modeled behavior is in accordance with observations in the Yangtze Estuary. To treat these unbalanced systems with a one-dimensional numerical model, we propose a moving (Lagrangian) framework in which a stable cross-sectional shape and progradation speed can be derived for growing tidal flats, as a function of the wave climate and the sediment concentration in deeper water.

  8. Development of a fast multi-line x-ray CT detector for NDT

    Science.gov (United States)

    Hofmann, T.; Nachtrab, F.; Schlechter, T.; Neubauer, H.; Mühlbauer, J.; Schröpfer, S.; Ernst, J.; Firsching, M.; Schweiger, T.; Oberst, M.; Meyer, A.; Uhlmann, N.

    2015-04-01

    Typical X-ray detectors for non-destructive testing (NDT) are line detectors or area detectors, like e.g. flat panel detectors. Multi-line detectors are currently only available in medical Computed Tomography (CT) scanners. Compared to flat panel detectors, line and multi-line detectors can achieve much higher frame rates. This allows time-resolved 3D CT scans of an object under investigation. Also, an improved image quality can be achieved due to reduced scattered radiation from object and detector themselves. Another benefit of line and multi-line detectors is that very wide detectors can be assembled easily, while flat panel detectors are usually limited to an imaging field with a size of approx. 40 × 40 cm2 at maximum. The big disadvantage of line detectors is the limited number of object slices that can be scanned simultaneously. This leads to long scan times for large objects. Volume scans with a multi-line detector are much faster, but with almost similar image quality. Due to the promising properties of multi-line detectors their application outside of medical CT would also be very interesting for NDT. However, medical CT multi-line detectors are optimized for the scanning of human bodies. Many non-medical applications require higher spatial resolutions and/or higher X-ray energies. For those non-medical applications we are developing a fast multi-line X-ray detector.In the scope of this work, we present the current state of the development of the novel detector, which includes several outstanding properties like an adjustable curved design for variable focus-detector-distances, conserving nearly uniform perpendicular irradiation over the entire detector width. Basis of the detector is a specifically designed, radiation hard CMOS imaging sensor with a pixel pitch of 200 μ m. Each pixel has an automatic in-pixel gain adjustment, which allows for both: a very high sensitivity and a wide dynamic range. The final detector is planned to have 256 lines of

  9. Pyroelectric x-ray detectors and x-ray pyrometers

    International Nuclear Information System (INIS)

    This paper discusses pyroelectric detectors which are very promising x-ray detectors for intense pulsed x-ray/γ-ray measurements and can be used as x-ray pyrometers. They are fast, passive, and inherently flat in spectral response for low energy x-rays. The authors report tests of LiTaO3, Sr.5Ba.5Nb2O6 and LiNbO3 detectors at Nova laser with 1 ns low energy x-rays and at Zapp Z-pinch machine with 100 ns x-rays. The temporal and spectral responses are discussed

  10. Pyroelectric x-ray detectors and x-ray pyrometers

    International Nuclear Information System (INIS)

    Pyroelectric detectors are very promising x-ray detectors for intense pulsed x-ray/γ-ray measurements and can be used as x-ray pyrometers. They are fast, passive, and inherently flat in spectral response for low-energy x rays. We report our tests of LiTaO3 detectors at Nova laser with 1-ns low-energy x rays and at Zapp Z-pinch machine with 100-ns x rays. The temporal and spectral responses are discussed

  11. Rotating detectors and Mach's principle

    Energy Technology Data Exchange (ETDEWEB)

    Paola, R.D.M. de; Svaiter, N.F

    2000-08-01

    In this work we consider a quantum version of Newton{sup s} bucket experiment in a fl;at spacetime: we take an Unruh-DeWitt detector in interaction with a real massless scalar field. We calculate the detector's excitation rate when it is uniformly rotating around some fixed point and the field is prepared in the Minkowski vacuum and also when the detector is inertial and the field is in the Trocheries-Takeno vacuum state. These results are compared and the relations with Mach's principle are discussed. (author)

  12. The HERMES Recoil Detector

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Weilin [II. Physikalisches Institut, JLU Giessen, Heinrich-Buff-Ring 16, 35392 Giessen (Germany)

    2008-07-01

    The HERMES Collaboration at HERA constructed and installed a new Recoil Detector to upgrade the existed spectrometer. This detector is designed to measure recoil protons in hard exclusive processes which provide access to the orbital angular momentum of quarks. The Recoil Detector consists of a silicon detector surrounding the target cell inside the beam vacuum, a scintillating fiber tracker and a photon detector. All three detectors are located inside a solenoidal magnet which provides a 1 T longitudinal magnetic field. The Recoil Detector was installed in January 2006 and data taking lasted until the end of HERA operation in June 2007. Results on the detector performance will be presented here.

  13. Improved germanium well detectors

    International Nuclear Information System (INIS)

    Germanium well detectors with metal surface barrier contact are comparable for general use with conventional germanium coaxial detectors. They offer very high sensitivity, the highest presently available

  14. MUON DETECTOR

    CERN Multimedia

    F. Gasparini

    DT As announced in the previous Bulletin MU DT completed the installation of the vertical chambers of barrel wheels 0, +1 and +2. 242 DT and RPC stations are now installed in the negative barrel wheels. The missing 8 (4 in YB-1 and 4 in YB-2) chambers can be installed only after the lowering of the two wheels into the UX cavern, which is planned for the last quarter of the year. Cabling on the surface of the negative wheels was finished in May after some difficulties with RPC cables. The next step was to begin the final commissioning of the wheels with the final trigger and readout electronics. Priority was giv¬en to YB0 in order to check everything before the chambers were covered by cables and services of the inner detectors. Commissioning is not easy since it requires both activity on the central and positive wheels underground, as well as on the negative wheels still on the surface. The DT community is requested to commission the negative wheels on surface to cope with a possible lack of time a...

  15. Aspects of warm-flat directions

    CERN Document Server

    Matsuda, Tomohiro

    2009-01-01

    We consider the evolution of the flat direction when there is a significant dissipation of the kinetic energy. The field may obtain Hubble-scale mass, but a slow-roll is possible due to the damping caused by the dissipation. Besides the damping effect, radiation may be created continuously by the dissipation and may enhance the fluctuations of the field. These effects may alter the usual cosmological scenarios associated with the flat direction. An example is the Affleck-Dine mechanism in which the dissipation may create significant (both qualitative and quantitative) discrepancies between the cold and the warm scenarios. We discuss several mechanisms of generating curvature perturbations that can be related to the warm-flat direction.

  16. Intermittent tracking of flat plate collectors

    International Nuclear Information System (INIS)

    A theoretical analysis of different intervals of intermittent two-axis tracking of the sun, on the amount of annual energy received by flat-plate collectors, has been carried out. The analysis was done for Ipoh, a city near the university at a latitude of 40 34 North in Malaysia. For the analysis, a computer program was developed to calculate the solar insulation according to the interval settings, considering ASHRAE Standard Sky assumption. Both direct and diffused components of solar radiation have been considered. The tracking system was targeted for flat plate collectors where the degree of tracking accuracy would be much lower Hence, the tracking mechanism will be much simpler and lower in costs. Results showed that by a 3-hour intermittent tracking, a flat-plate collector could get as much as 35% more annual energy than a fixed one. The 3-hour interval tracking greatly simplifies the gear mechanism from the motor to the solar collector. (Author)

  17. The flat phase of quantum polymerized membranes

    CERN Document Server

    Coquand, O

    2016-01-01

    We investigate the flat phase of quantum polymerized phantom membranes by means of a nonperturbative renormalization group approach. We first implement this formalism for general quantum polymerized membranes and derive the flow equations that encompass both quantum and thermal fluctuations. We then deduce and analyze the flow equations relevant to study the flat phase and discuss their salient features : quantum to classical crossover and, in each of these regimes, strong to weak coupling crossover. We finally illustrate these features in the context of free standing graphene physics.

  18. Scalar Curvature and Intrinsic Flat Convergence

    CERN Document Server

    Sormani, Christina

    2016-01-01

    Herein we present open problems and survey examples and theorems concerning sequences of Riemannian manifolds with uniform lower bounds on scalar curvature and their limit spaces. Examples of Gromov and of Ilmanen which naturally ought to have certain limit spaces do not converge with respect to smooth or Gromov-Hausdorff convergence. Thus we focus here on the notion of Intrinsic Flat convergence, developed jointly with Wenger. This notion has been applied successfully to study sequences that arise in General Relativity. Gromov has suggested it should be applied in other settings as well. We first review intrinsic flat convergence, its properties, and its compactness theorems, before presenting the applications and the open problems.

  19. Detector simulation needs for detector designers

    International Nuclear Information System (INIS)

    Computer simulation of the components of SSC detectors and of the complete detectors will be very important for the designs of the detectors. The ratio of events from interesting physics to events from background processes is very low, so detailed understanding of detector response to the backgrounds is needed. Any large detector for the SSC will be very complex and expensive and every effort must be made to design detectors which will have excellent performance and will not have to undergo major rebuilding. Some areas in which computer simulation is particularly needed are pattern recognition in tracking detectors and development of shower simulation code which can be trusted as an aid in the design and optimization of calorimeters, including their electron identification performance. Existing codes require too much computer time to be practical and need to be compared with test beam data at energies of several hundred GeV. Computer simulation of the processing of the data, including electronics response to the signals from the detector components, processing of the data by microprocessors on the detector, the trigger, and data acquisition will be required. In this report we discuss the detector simulation needs for detector designers

  20. Contribution to the manufacture of silicon semiconductor detectors

    International Nuclear Information System (INIS)

    Production methods used for making silicon semi-conductor detectors at the Nuclear Physics Laboratory in Grenoble are described. Detectors are of two types, either the lithium-compensated p.i.n. type up to 3.5 mm thick, or the surface barrier type from 2 mm down to 10 μ thick. The research into the surface barrier type concerned essentially the resolving power of the chemical contact obtained by Be evaporation (or Ni deposit), after a chemical attack (type C.P.I.) which is thickness-controlled and which gives a low surface current and a satisfactory flatness. The resolving power obtained (α 8.78 MeV, T ≅ - 20 deg. C) is of the order of 20 keV for thick detectors (surface barrier) and ≅ 50 keV for very thin detectors (10 μ), and for p.i.n. type detectors (≅ 50 keV at T + 20 deg. C). (author)

  1. Quantitative digital radiography with two dimensional flat panels

    International Nuclear Information System (INIS)

    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)

  2. MSSM flat direction as a curvaton

    CERN Document Server

    Enqvist, Kari; Kasuya, S; Mazumdar, A; Enqvist, Kari; Jokinen, Asko; Kasuya, Shinta; Mazumdar, Anupam

    2003-01-01

    We study in detail the possibility that the flat directions of the Minimal Supersymmetric Standard Model (MSSM) could act as a curvaton and generate the observed adiabatic density perturbations. For that the flat direction energy density has to dominate the Universe at the time when it decays. We point out that this is not possible if the inflaton decays into MSSM degrees of freedom. If the inflaton is completely in the hidden sector, its decay products do not couple to the flat direction, and the flat direction curvaton can dominate the energy density. This requires the absence of a Hubble-induced mass for the curvaton, e.g. by virtue of the Heisenberg symmetry. In the case of hidden radiation, $n=9$ is the only admissible direction; for other hidden equations of state, directions with lower $n$ may also dominate. We show that the MSSM curvaton is further constrained severely by the damping of the fluctuations, and as an example, demonstrate that in no-scale supergravity it would fragment into $Q$ balls rath...

  3. Remediation of the Maxey Flats Site

    International Nuclear Information System (INIS)

    This report describes issues associated with remedial action of Maxey Flats, a low-level radioactive waste disposal site from 1963-1977, located in Fleming County, Kentucky. Present remedial action alternatives being considered are discussed along with emergency plans, ground water monitoring plans, and budgets

  4. Design scenarios for flat panel photobioreactors

    NARCIS (Netherlands)

    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

  5. Promoting Employability in a "Flat" World

    Science.gov (United States)

    Parker, Polly

    2008-01-01

    T. L. Friedman (2005) described a "flat" world platform where competition and collaboration take place in real time among people all over the planet. Implications exist for people to assume responsibility for managing their own careers and ensuring their own security in a global economy. This article addresses those challenges from both the…

  6. Vortices in theories with flat directions

    NARCIS (Netherlands)

    Achucarro, A; Davis, AC; Pickles, M; Urrestilla, J

    2002-01-01

    In theories with flat directions containing vortices, such as supersymmetric QED, there is a vacuum selection effect in the allowed asymptotic configurations. We explain the role played by gauge fields in this effect and give a simple criterion for determining what vacua will be chosen, namely, thos

  7. 40 CFR 230.42 - Mud flats.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Mud flats. 230.42 Section 230.42 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) OCEAN DUMPING SECTION 404(b)(1) GUIDELINES FOR SPECIFICATION OF DISPOSAL SITES FOR DREDGED OR FILL MATERIAL Potential Impacts on...

  8. Asymptotically flat and regular Cauchy data

    CERN Document Server

    Dain, S

    2002-01-01

    I describe the construction of a large class of asymptotically flat initial data with non-vanishing mass and angular momentum for which the metric and the extrinsic curvature have asymptotic expansions at space-like infinity in terms of powers of a radial coordinate. I emphasize the motivations and the main ideas behind the proofs.

  9. 8. Asymptotically Flat and Regular Cauchy Data

    Science.gov (United States)

    Dain, Sergio

    I describe the construction of a large class of asymptotically flat initial data with non-vanishing mass and angular momentum for which the metric and the extrinsic curvature have asymptotic expansions at space-like infinity in terms of powers of a radial coordinate. I emphasize the motivations and the main ideas behind the proofs.

  10. Solid state detector design

    International Nuclear Information System (INIS)

    Much has been charged particle detector radiation detector made by the industry, especially those engaged in the development of detection equipment and components. The development and further research will be made solid state detector with silicon material. To be able to detect charged particles (radiation), required the processing of silicon material into the detector material. The method used to make silicon detector material is a lithium evaporations. Having formed an intrinsic region contactor installation process, and with testing. (author)

  11. 非晶硒平板探测器DR与CR模拟病变描述和剂量降低的对比研究%Amorphous selenium flat-panel detector digital radiography versus computed radiography: phantom study of depiction of simulated lesion and dose reduction

    Institute of Scientific and Technical Information of China (English)

    曾勇明; 吴富荣; 张志伟; 欧阳羽; 谭秀洪; 金瑞

    2008-01-01

    Objective To compare an amorphous selenium fiat-panel detector digital radiography(DR) with a computed radiography(CR) for the depiction of simulated pulmonary lesion,as well as for evaluation of dose reduction.Methods Simulated linear,reticular,and nodular lesion were located in all anthropomorphic chest phantom.The phantom was exposed by DR and CR with different mAs sets.The entrance surface doses were recorded for all images.Hard copy images were generated at different dose levels.Images were presented in a random order to four independent radiologists.They subjectively rated the visibility of simulated pulmonary lesion. Statistical significance of difference was analvsed with wilcoxon test.Resuits The visibility of simulated linear and reticular lesions on the images obtained with DR was superior to the images from CR at 2.0 and 3.2 mAs.P 0.05).DR was superior to CR in detection sinail nodular(diameter0.05).2.0、3.2、5.0、6.3 mAs曝光档,对于小结节(直径小于10 mm)的检测DR均优于CR(Z:-2.237,P=0.018;Z=-2.384,P=0.017;Z=-2.388,P=0.017;Z=-2.366,P=0.018).当3种模拟肺部病变都显示清楚时.用非晶硒DR系统的入射体表剂量降低约65%.结论 对微小低对比病变的描述,非晶硒平板探测器DR优于CR且明显地降低曝光剂晕.

  12. Large area x-ray detectors for cargo radiography

    Science.gov (United States)

    Bueno, C.; Albagli, D.; Bendahan, J.; Castleberry, D.; Gordon, C.; Hopkins, F.; Ross, W.

    2007-04-01

    Large area x-ray detectors based on phosphors coupled to flat panel amorphous silicon diode technology offer significant advances for cargo radiologic imaging. Flat panel area detectors provide large object coverage offering high throughput inspections to meet the high flow rate of container commerce. These detectors provide excellent spatial resolution when needed, and enhanced SNR through low noise electronics. If the resolution is reduced through pixel binning, further advances in SNR are achievable. Extended exposure imaging and frame averaging enables improved x-ray penetration of ultra-thick objects, or "select-your-own" contrast sensitivity at a rate many times faster than LDAs. The areal coverage of flat panel technology provides inherent volumetric imaging with the appropriate scanning methods. Flat panel area detectors have flexible designs in terms of electronic control, scintillator selection, pixel pitch, and frame rates. Their cost is becoming more competitive as production ramps up for the healthcare, nondestructive testing (NDT), and homeland protection industries. Typically used medical and industrial polycrystalline phosphor materials such as Gd2O2S:Tb (GOS) can be applied to megavolt applications if the phosphor layer is sufficiently thick to enhance x-ray absorption, and if a metal radiator is used to augment the quantum detection efficiency and reduce x-ray scatter. Phosphor layers ranging from 0.2-mm to 1-mm can be "sandwiched" between amorphous silicon flat panel diode arrays and metal radiators. Metal plates consisting of W, Pb or Cu, with thicknesses ranging from 0.25-mm to well over 1-mm can be used by covering the entire area of the phosphor plate. In some combinations of high density metal and phosphor layers, the metal plate provides an intensification of 25% in signal due to electron emission from the plate and subsequent excitation within the phosphor material. This further improves the SNR of the system.

  13. Flat-on-flat, nonconstrained, compression molded polyethylene total knee replacement.

    Science.gov (United States)

    Ritter, M A; Worland, R; Saliski, J; Helphenstine, J V; Edmondson, K L; Keating, E M; Faris, P M; Meding, J B

    1995-12-01

    Flat-on-flat, posterior cruciate ligament-sparing total knee prostheses recently have shown problems of wear, loosening, and multiple design changes. Two thousand one Anatomical Graduated Components total knee arthroplasties with compression molded, nonmodular polyethylene tibial components were done between 1983 and 1991 at 3 institutions. All knees were evaluated clinically and radiographically every 2 to 3 years; 71 knees were seen in followup > 10 years. There were 8 failures secondary to revision (5 tibial failures; 2 secondary to metalosis from patellar polyethylene dissociation; and 3 femoral failures) resulting in a 98% survival rate at 10 years. The tibial design was flat-on-flat with a compression molded polyethylene that the authors believe is the primary reason for its success. PMID:7497689

  14. Spatial Distribution of Polychlorinated Biphenyls (PCBs) Contaminants in the Tidal-flat Sediments of Yangtze Estuary

    Institute of Scientific and Technical Information of China (English)

    Chen Manrong; Yu Lizhong; Xu Shiyuan; Feng Ke; Han Xiaofei

    2003-01-01

    PCBs pollutants are measured on tidal-flat sediments of Yangtze estuary by a high resolution capillary column gas chromatography ( HP6890 ) equipped with an 63Ni electron capture detector ( ECD ). The concentration tendency of PCBs is Phragmites zone > Scirpus zone > bare mudflats. There are linear relations between PCBs and TOC and > 63 μ m grain size percentage ( in volume ). The low chlorinated congeners may be more important than the high chlorinated congeners in this area. PCBs prefer to accumulate in the sediments near sewage outlets and Phragmites zone. The sediments′ PCBs pollution ( 10.7 ~ 28.6 ng/g, dry weight ) in the Yangtze estuary tidal-flat is less serious than that of the most of other areas in the world. But the detected ratio is 100 %, even the Jiuduansha shoal has detected PCBs, so much attention should be paid to this area for PCBs.

  15. Photon irradiation response of photonic crystal fibres and flat fibres at radiation therapy doses

    International Nuclear Information System (INIS)

    Radiation effects of photon irradiation in pure Photonic Crystal Fibres (PCF) and Flat fibres (FF) are still much less investigated in thermoluminescense dosimetry (TLD). We have reported the TL response of PCF and FF subjected to 6 MV photon irradiation. The proposed dosimeter shows good linearity at doses ranging from 1 to 4 Gy. The small size of these detectors points to its use as a dosimeter at megavoltage energies, where better tissue-equivalence and the Bragg–Gray cavity theory prevails. - Highlights: • First study about radiation effects of photon irradiation in pure Photonic Crystal Fibres (PCF) and Flat fibres (FF). • PCF and FF. have been found to have good dose linearity (up to 4 Gy). • The value of Zeff obtained is in the range of 10.3–11.3 and 11.3–11.8 for PCF and FF respectively

  16. GADRAS Detector Response Function.

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, Dean J.; Harding, Lee; Thoreson, Gregory G; Horne, Steven M.

    2014-11-01

    The Gamma Detector Response and Analysis Software (GADRAS) applies a Detector Response Function (DRF) to compute the output of gamma-ray and neutron detectors when they are exposed to radiation sources. The DRF is fundamental to the ability to perform forward calculations (i.e., computation of the response of a detector to a known source), as well as the ability to analyze spectra to deduce the types and quantities of radioactive material to which the detectors are exposed. This document describes how gamma-ray spectra are computed and the significance of response function parameters that define characteristics of particular detectors.

  17. The MINOS Detectors

    CERN Document Server

    Grashorn, A H E W

    2005-01-01

    The Main Injector Neutrino Oscillation Search (MINOS) experiment's primary goal is the precision measurement of the neutrino oscillation parameters in the atmospheric neutrino sector. This long-baseline experiment uses Fermilab's NuMI beam, measured with a Near Detector at Fermilab, and again 735 km later using a Far Detector in the Soudan Mine Underground Lab in northern Minnesota. The detectors are magnetized iron/scintillator calorimeters. The Far Detector has been operational for cosmic ray and atmospheric neutrino data from July of 2003, the Near Detector from September 2004, and the NuMI beam started in early 2005. This poster presents details of the two detectors.

  18. Efficient flat metasurface lens for terahertz imaging.

    Science.gov (United States)

    Yang, Quanlong; Gu, Jianqiang; Wang, Dongyang; Zhang, Xueqian; Tian, Zhen; Ouyang, Chunmei; Singh, Ranjan; Han, Jiaguang; Zhang, Weili

    2014-10-20

    Metamaterials offer exciting opportunities that enable precise control of amplitude, polarization and phase of the light beam at a subwavelength scale. A gradient metasurface consists of a class of anisotropic subwavelength metamaterial resonators that offer abrupt amplitude and phase changes, thus enabling new applications in optical device design such as ultrathin flat lenses. We propose a highly efficient gradient metasurface lens based on a metal-dielectric-metal structure that operates in the terahertz regime. The proposed structure consists of slotted metallic resonator arrays on two sides of a thin dielectric spacer. By varying the geometrical parameters, the metasurface lens efficiently manipulates the spatial distribution of the terahertz field and focuses the beam to a spot size on the order of a wavelength. The proposed flat metasurface lens design is polarization insensitive and works efficiently even at wide angles of incidence. PMID:25401626

  19. Modelling Flat Spring performance using FEA

    International Nuclear Information System (INIS)

    This paper reports how the stiffness of a Flat Spring can be predicted using nonlinear Finite Element Analysis (FEA). The analysis of a Flat Spring is a nonlinear problem involving contact mechanics, geometric nonlinearity and material property nonlinearity. Research has been focused on improving the accuracy of the model by identifying and exploring the significant assumptions contributing to errors. This paper presents results from some of the models developed using FEA software. The validation process is shown to identify where improvements can be made to the model assumptions to increase the accuracy of prediction. The goal is to achieve an accuracy level of ±10 % as the intention is to replace practical testing with FEA modelling, thereby reducing the product development time and cost. Results from the FEA models are compared with experimental results to validate the accuracy.

  20. Towards a flat 45%-efficient concentrator module

    Energy Technology Data Exchange (ETDEWEB)

    Mohedano, Rubén, E-mail: rmohedano@lpi-europe.com; Hernandez, Maikel; Vilaplana, Juan; Chaves, Julio; Sorgato, S.; Falicoff, Waqidi [LPI, Altadena, CA, USA and Madrid (Spain); Miñano, Juan C.; Benitez, Pablo [LPI, Altadena, CA, USA and Madrid (Spain); Universidad Politécnica de Madrid (UPM), Campus de Montegancedo, Madrid (Spain)

    2015-09-28

    The so-called CCS{sup 4}FK is an ultra-flat photovoltaic system of high concentration and high efficiency, with potential to convert, ideally, the equivalent of a 45% of direct solar radiation into electricity by optimizing the usage of sun spectrum and by collecting part of the diffuse radiation, as a flat plate does. LPI has recently finished a design based on this concept and is now developing a prototype based on this technology, thanks to the support of FUNDACION REPSOL-Fondo de Emprendedores, which promotes entrepreneur projects in different areas linked to energy. This works shows some details of the actual design and preliminary potential performance expected, according to accurate spectral simulations.

  1. Towards a flat 45%-efficient concentrator module

    Science.gov (United States)

    Mohedano, Rubén; Hernandez, Maikel; Vilaplana, Juan; Chaves, Julio; Miñano, Juan C.; Benitez, Pablo; Sorgato, S.; Falicoff, Waqidi

    2015-09-01

    The so-called CCS4FK is an ultra-flat photovoltaic system of high concentration and high efficiency, with potential to convert, ideally, the equivalent of a 45% of direct solar radiation into electricity by optimizing the usage of sun spectrum and by collecting part of the diffuse radiation, as a flat plate does. LPI has recently finished a design based on this concept and is now developing a prototype based on this technology, thanks to the support of FUNDACION REPSOL-Fondo de Emprendedores, which promotes entrepreneur projects in different areas linked to energy. This works shows some details of the actual design and preliminary potential performance expected, according to accurate spectral simulations.

  2. Standard specification for silvered flat glass mirror

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This specification covers the requirements for silvered flat glass mirrors of rectangular shape supplied as cut sizes, stock sheets or as lehr ends and to which no further processing (such as edgework or other fabrication) has been done. 1.2 This specification covers the quality requirements of silvered annealed monolithic clear and tinted flat glass mirrors up to 6 mm (¼ in.) thick. The mirrors are intended to be used indoors for mirror glazing, for components of decorative accessories or for similar uses. 1.3 This specification does not address safety glazing materials nor requirements for mirror applications. Consult model building codes and other applicable standards for safety glazing applications. 1.4 Mirrors covered in this specification are not intended for use in environments where high humidity or airborne corrosion promoters, or both, are consistently present (such as swimming pool areas, ocean-going vessels, chemical laboratories and other corrosive environments). 1.5 The dimensional val...

  3. History of Rocky Flats waste streams

    International Nuclear Information System (INIS)

    An analysis of the waste streams at Rocky Flats was done to provide information for the Waste Certification program. This program has involved studying the types and amounts of retrievable transuranic (TRU) waste from Rocky Flats that is stored at the Idaho National Engineering Laboratory (INEL). The information can be used to estimate the types and amounts of waste that will need to be permanently stored in the Waste Isolation Pilot Plant (WIPP). The study covered mostly the eight-year period from June 1971 to June 1979. The types, amounts, and plutonium content of TRU waste and the areas or operations responsible for generating the waste are summarized in this waste stream history report. From the period studied, a total of 24,546,153 lbs of waste containing 211,148 g of plutonium currently occupies 709,497 cu ft of storage space at INEL

  4. Flat-spectrum, variable radio sources

    International Nuclear Information System (INIS)

    The general behavior of flat-spectrum (compact) radio sources is examined in terms of adiabatic-jet models. Two puzzling properties - namely, (1) the broad, rather flat spectrum (over a large range of radio frequencies) and (2) the relatively slow decay of burst amplitude (with decreasing radio frequency) - are explained. Acceptable models are characterized by the following: (1) a nearly conical, adiabatic jet, with conserved magnetic flux transverse to the axis of the jet; (2) prolonged injection (for which the duration of an event exceeds the apparent transit time scale); and (3) a transparent spectral index which is not too steep. It is suggested that the acceleration mechanism in the core of compact jets may differ substantially from that far from the core, producing a flatter electron number index s = 1.4-2.6. 42 references

  5. Gorenstein flatness and injectivity over Gorenstein rings

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Let R be a Gorenstein ring.We prove that if I is an ideal of R such that R/I is a semi-simple ring,then the Gorenstein flat dimension of R/I as a right R-module and the Gorenstein injective dimension of R/I as a left R-module are identical.In addition,we prove that if R→S is a homomorphism of rings and SE is an injective cogenerator for the category of left S-modules,then the Gorenstein flat dimension of S as a right R-module and the Gorenstein injective dimension of E as a left R-module are identical.We also give some applications of these results.

  6. Improving the durability of flat roof constructions

    DEFF Research Database (Denmark)

    Rudbeck, Claus Christian; Svendsen, Sv Aa Højgaard

    Flat roof constructions are mainly used on commercial, institutional and industrial buildings, where insulation is placed on top of the load-bearing deck and then covered with a roof membrane. Through time, there is a risk that the membrane will allow water passage as holes might form due to...... there is no easy method of drying it. To be able to dry the insulation, and thereby regain the functional requirements of the roofing system, two new solutions for insulating flat roofs with existing materials are proposed for high density mineral wool and expanded polystyrene. Monitoring equipment are......, they have a longer life span reducing the overall cost. Furthermore systems, where moisture can be removed, offer a high probability that the thermal conductivity remains at its designed value through the entire life of the roofing system. If the roofing membrane should fail, the insulation can be...

  7. Towards a flat 45%-efficient concentrator module

    International Nuclear Information System (INIS)

    The so-called CCS4FK is an ultra-flat photovoltaic system of high concentration and high efficiency, with potential to convert, ideally, the equivalent of a 45% of direct solar radiation into electricity by optimizing the usage of sun spectrum and by collecting part of the diffuse radiation, as a flat plate does. LPI has recently finished a design based on this concept and is now developing a prototype based on this technology, thanks to the support of FUNDACION REPSOL-Fondo de Emprendedores, which promotes entrepreneur projects in different areas linked to energy. This works shows some details of the actual design and preliminary potential performance expected, according to accurate spectral simulations

  8. Flat roof integration. CPT solar (AET IV)

    Energy Technology Data Exchange (ETDEWEB)

    Chianese, D.; Pola, I.; Bernasconi, A.; Bura, E.; Cereghetti, N.; Realini, A.; Pasinelli, P.; Rioggi, S.

    2007-11-15

    This illustrated final report for the Swiss Federal Office of Energy (SFOE) takes a look at a 15.4 kWp solar power installation in Trevano, Switzerland, that features flexible amorphous silicon triple-junction modules, mounted nearly horizontally and directly laminated to flexible polyolefin membranes that form the covering of a flat roof. The main objective of this study was to verify in which order of magnitude the better thermal behaviour of amorphous silicon cells can compensate for losses due to the quasi-horizontal roof integration (lower irradiation and higher reflection), and thus be competitive in the flat roof construction and refurbishment markets. The modules used and their characteristics are described. Performance, temperature levels and energy-production are reviewed for the panels of the installation. The performance of the inverter used is also reviewed. Data on temperatures and production are presented in graphical form and optical losses are examined.

  9. Improving the durability of flat roof constructions

    DEFF Research Database (Denmark)

    Rudbeck, Claus Christian; Svendsen, Sv Aa Højgaard

    there is no easy method of drying it. To be able to dry the insulation, and thereby regain the functional requirements of the roofing system, two new solutions for insulating flat roofs with existing materials are proposed for high density mineral wool and expanded polystyrene. Monitoring equipment are......Flat roof constructions are mainly used on commercial, institutional and industrial buildings, where insulation is placed on top of the load-bearing deck and then covered with a roof membrane. Through time, there is a risk that the membrane will allow water passage as holes might form due to...... weathering effects or physical loads. Water will then enter the insulation, and as a vapor retarder is normally found below the insulation thus trapping the water in the insulation, the leak can remain undetected for a long period. When the leak is finally discovered, the insulation has to be discharged as...

  10. Immobilization of Rocky Flats graphite fines residues

    International Nuclear Information System (INIS)

    The Savannah River Technology Center (SRTC) is developing an immobilization process for graphite fines residues generated during nuclear materials production activities at the Rocky Flats Environmental Technology Site (Rocky Flats). The continued storage of this material has been identified as an item of concern. The residue was generated during the cleaning of graphite casting molds and potentially contains reactive plutonium metal. The average residue composition is 73 wt% graphite, 15 wt% calcium fluoride (CaF2), and 12 wt% plutonium oxide (PuO2). Approximately 950 kg of this material are currently stored at Rocky Flats. The strategy of the immobilization process is to microencapsulate the residue by mixing with a sodium borosilicate (NBS) glass frit and heating at nominally 700 C. The resulting waste form would be sent to the Waste Isolation Pilot Plant (WIPP) for disposal. Since the PuO2 concentration in the residue averages 12 wt%, the immobilization process was required to meet the intent of safeguards termination criteria by limiting plutonium recoverability based on a test developed by Rocky Flats. The test required a plutonium recovery of less than 4 g/kg of waste form when a sample was leached using a nitric acid/CaF2 dissolution flowsheet. Immobilization experiments were performed using simulated graphite fines with cerium oxide (CeO2) as a surrogate for PuO2 and with actual graphite fines residues. Small-scale surrogate experiments demonstrated that a 4:1 frit to residue ratio was adequate to prevent recovery of greater than 4 g/kg of cerium from simulated waste forms. Additional experiments investigated the impact of varying concentrations of CaF2 and the temperature/heating time cycle on the cerium recovery. Optimal processing conditions developed during these experiments were subsequently demonstrated at full-scale with surrogate materials and on a smaller scale using actual graphite fines

  11. Microwave solidification development for Rocky Flats waste

    International Nuclear Information System (INIS)

    The Microwave Engineering Team at the Rocky Flats Plant has developed a production-scale system for the treatment of hazardous, radioactive, and mixed wastes using microwave energy. The system produces a vitreous final form which meets the acceptance criteria for shipment and disposal. The technology also has potential for application on various other waste streams from the public and private sectors. Technology transfer opportunities are being identified and pursued for commercialization of the microwave solidification technology

  12. Flat band superconductivity in strained Dirac materials

    OpenAIRE

    Kauppila, V. J.; Aikebaier, F.; Heikkilä, T. T.

    2016-01-01

    We consider superconducting properties of a two-dimensional Dirac material such as graphene under strain that produces a flat band spectrum in the normal state. We show that in the superconducting state, such a model results in a highly increased critical temperature compared to the case without the strain, inhomogenous order parameter with two-peak shaped local density of states and yet a large and almost uniform and isotropic supercurrent. This model could be realized in strained graphene o...

  13. Soil decontamination at Rocky Flats Plant

    International Nuclear Information System (INIS)

    A description is given of work being done at Rocky Flats Plant (RFP) to decontaminate soil contaminated with plutonium-239. How the contamination came about is described, as well as what has been done to contain it while decontamination methods are being developed. The purpose of the work is to decontaminate the soil so that it can be returned to the site instead of having to package, ship, and store it

  14. Differential flat control for rotorcraft trajectory tracking

    OpenAIRE

    Nan Zhang; Geanina Andrei; Antoine Drouin; Felix Mora-Camino

    2009-01-01

    The purpose of this communication is to investigate the usefulness of the differential flatness control approach to solve the trajectory tracking problem for a four rotor aircraft. After introducing simplifying assumptions, the flight dynamics equations for the four rotor aircraft are considered. A trajectory tracking control structure based on a two layer non linear approach is then proposed. A supervision level is introduced to take into account the actuators limitations.

  15. Stable flatness of nonarchimedean hyperenveloping algebras

    OpenAIRE

    Schmidt, Tobias

    2008-01-01

    Let L be a p-adic local field and g a finite dimensional Lie algebra over L. We show that its hyperenveloping algebra F(g) is a stably flat completion of its universal enveloping algebra. As a consequence the relative cohomology for the locally convex algebra F(g) coincides with the underlying Lie algebra cohomology. Final version. Some minor items corrected. Appeared in Journal of Algebra (2010).

  16. Wash Flats Management Plan Chincoteague National Wildlife Refuge 1980

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Wash Flats impoundments comprise an area of approximately 1,200 acres. Prior to 1963, the Wash Flats was subject to periodic wash-over during extremely high...

  17. Shrinkage and trajectory of the flat jet with inclination angle

    Institute of Scientific and Technical Information of China (English)

    Shufeng Ye; Yusheng Xie; Hongzhi Guo; Ye Huang; Shantong Jin

    2003-01-01

    The performance of the flat jet with an inclination angle was investigated by a water model. A mathematical model for theshrinkage and the trajectory of the flat jet with an inclination angle was derived theoretically and verified by experimental data of thewater model. The experimental results indicate that the inclination angle (α) has no influence on the shrinkage of the flat jet, theshrinkage of the flat jet along the width direction decreases with the increasing of the initial velocity at the exit (u0) and the initialthickness of the flat jet (t0). Enough bigger initial exit velocity (u0) and initial thickness can suppress the shrinkage of the flat jetalong the width direction and keep the flat jet stabilized. In addition, the trajectory of the flat jet with an inclination angle is parabolicand must be taking into consideration when to determine the striking distance.

  18. Drift Chambers detectors; Detectores de deriva

    Energy Technology Data Exchange (ETDEWEB)

    Duran, I.; Martinez laso, L.

    1989-07-01

    We present here a review of High Energy Physics detectors based on drift chambers. The ionization, drift diffusion, multiplication and detection principles are described. Most common drift media are analysed, and a classification of the detectors according to its geometry is done. Finally the standard read-out methods are displayed and the limits of the spatial resolution are discussed. (Author) 115 refs.

  19. Flat-Fielding BATSE Occultation Data for use in a Hard X-Ray All Sky Survey

    OpenAIRE

    Shaw, S. E.; Bird, A. J.; Dean, A.J.; Diallo, N.; Ferguson, C.; J. Knodlseder(CNRS, IRAP, Toulouse, France); Lockley, J. J.; Westmore, M. J.; Willis, D. R.

    2001-01-01

    The BATSE mission aboard CGRO can be used to observe hard X-ray sources by using the Earth occultation method. This method relies on measuring a step in the count rate profile in each BATSE detector as a source rises above or sets below the Earth's limb. A major problem in determining the step sizes (and hence the flux) is in extracting the steps from the varying background. A technique for flat-fielding the response of gamma ray detectors has been developed at Southampton. The technique uses...

  20. Graphene nanoribbons production from flat carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Melo, W. S.; Guerini, S.; Diniz, E. M., E-mail: eduardo.diniz@ufma.br [Departamento de Física, Universidade Federal do Maranhão, São Luís - MA 65080-805 (Brazil)

    2015-11-14

    Graphene nanoribbons are of great interest for pure and applied sciences due to their unique properties which depend on the nanoribbon edges, as, for example, energy gap and antiferromagnetic coupling. Nevertheless, the synthesis of nanoribbons with well-defined edges remains a challenge. To collaborate with this subject, here we propose a new route for the production of graphene nanoribbons from flat carbon nanotubes filled with a one-dimensional chain of Fe atoms by first principles calculations based on density functional theory. Our results show that Fe-filled flat carbon nanotubes are energetically more stable than non flattened geometries. Also we find that by hydrogenation or oxygenation of the most curved region of the Fe-filled flat armchair carbon nanotube, it occurred a spontaneous production of zigzag graphene nanoribbons which have metallic or semiconducting behavior depending on the edge and size of the graphene nanoribbon. Such findings can be used to create a new method of synthesis of regular-edge carbon nanoribbons.

  1. Design scenarios for flat panel photobioreactors

    International Nuclear Information System (INIS)

    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%.

  2. Graphene nanoribbons production from flat carbon nanotubes

    International Nuclear Information System (INIS)

    Graphene nanoribbons are of great interest for pure and applied sciences due to their unique properties which depend on the nanoribbon edges, as, for example, energy gap and antiferromagnetic coupling. Nevertheless, the synthesis of nanoribbons with well-defined edges remains a challenge. To collaborate with this subject, here we propose a new route for the production of graphene nanoribbons from flat carbon nanotubes filled with a one-dimensional chain of Fe atoms by first principles calculations based on density functional theory. Our results show that Fe-filled flat carbon nanotubes are energetically more stable than non flattened geometries. Also we find that by hydrogenation or oxygenation of the most curved region of the Fe-filled flat armchair carbon nanotube, it occurred a spontaneous production of zigzag graphene nanoribbons which have metallic or semiconducting behavior depending on the edge and size of the graphene nanoribbon. Such findings can be used to create a new method of synthesis of regular-edge carbon nanoribbons

  3. How flat is our Universe really?

    International Nuclear Information System (INIS)

    Distance measurement provides no constraints on curvature independent of assumptions about the dark energy, raising the question, how flat is our Universe if we make no such assumptions? Allowing for general evolution of the dark energy equation of state with 20 free parameters that are allowed to cross the phantom divide, w(z)=−1, we show that while it is indeed possible to match the first peak in the Cosmic Microwave Background with non-flat models and arbitrary Hubble constant, H0, the full WMAP7 and supernova data alone imply −0.12k0 prior, this tightens significantly to Ωk=0.002±0.009. These constitute the most conservative and model-independent constraints on curvature available today, and illustrate that the curvature-dynamics degeneracy is broken by current data, with a key role played by the Integrated Sachs Wolfe effect rather than the distance to the surface of last scattering. If one imposes a quintessence prior on the dark energy (−1⩽w(z)⩽1) then just the WMAP7 and supernova data alone force the Universe to near flatness: Ωk=0.013±0.012. Finally, allowing for curvature, we find that all datasets are consistent with a Harrison–Zel'dovich spectral index, ns=1, at 2σ, illustrating the interplay between early and late Universe constraints

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

    International Nuclear Information System (INIS)

    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.)

  5. Tin Can Radiation Detector.

    Science.gov (United States)

    Crull, John L.

    1986-01-01

    Provides instructions for making tin can radiation detectors from empty aluminum cans, aluminum foil, clear plastic, copper wire, silica gel, and fine, unwaxed dental floss put together with tape or glue. Also provides suggestions for activities using the detectors. (JN)

  6. Forward tracking detectors

    Indian Academy of Sciences (India)

    Klaus Mönig

    2007-11-01

    Forward tracking is an essential part of a detector at the international linear collider (ILC). The requirements for forward tracking are explained and the proposed solutions in the detector concepts are shown.

  7. CMOS APS detector characterization for quantitative X-ray imaging

    Energy Technology Data Exchange (ETDEWEB)

    Endrizzi, Marco, E-mail: m.endrizzi@ucl.ac.uk [Dipartimento di Fisica, Università di Siena, Via Roma 56, 53100 Siena (Italy); Istituto Nazionale di Fisica Nucleare INFN, sezione di Pisa, 56127 Pisa (Italy); Oliva, Piernicola [Dipartimento di Chimica e Farmacia, Università di Sassari, via Piandanna 4, 07100 Sassari (Italy); Istituto Nazionale di Fisica Nucleare INFN, Sezione di Cagliari, 09042 Cagliari (Italy); Golosio, Bruno [Sezione di Matematica, Fisica e Ingegneria dell' Informazione, Università di Sassari, via Piandanna 4, 07100 Sassari (Italy); Istituto Nazionale di Fisica Nucleare INFN, Sezione di Cagliari, 09042 Cagliari (Italy); Delogu, Pasquale [Dipartimento di Fisica “E. Fermi”, Università di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Istituto Nazionale di Fisica Nucleare INFN, sezione di Pisa, 56127 Pisa (Italy)

    2013-03-01

    An X-ray Imaging detector based on CMOS Active Pixel Sensor and structured scintillator is characterized for quantitative X-ray imaging in the energy range 11–30 keV. Linearity, dark noise, spatial resolution and flat-field correction are the characteristics of the detector subject of investigation. The detector response, in terms of mean Analog-to-Digital Unit and noise, is modeled as a function of the energy and intensity of the X-rays. The model is directly tested using monochromatic X-ray beams and it is also indirectly validated by means of polychromatic X-ray-tube spectra. Such a characterization is suitable for quantitative X-ray imaging and the model can be used in simulation studies that take into account the actual performance of the detector.

  8. JADE muon detector

    Energy Technology Data Exchange (ETDEWEB)

    Allison, J.; Armitage, J.C.M.; Baines, J.T.M.; Ball, A.H.; Bamford, G.; Barlow, R.J.; Bowdery, C.K.; Chrin, J.T.M.; Duerdoth, I.P.; Glendinning, I.; Greenshaw, T.; Hassard, J.F.; Hill, P.; King, B.T.; Loebinger, F.K.; Macbeth, A.A.; McCann, H.; Mercer, D.; Mills, H.E.; Murphy, P.G.; Prosper, H.B.; Rowe, P.; Stephens, K.

    1985-08-01

    The JADE muon detector consists of 618 planar drift chambers interspersed between layers of hadron absorber. This paper gives a detailed description of the construction and operation of the detector as a whole and discusses the properties of the drift chambers. The muon detector has been operating successfully at PETRA for five years. (orig.).

  9. Gas filled detectors

    International Nuclear Information System (INIS)

    The main types of gas filled nuclear detectors: ionization chambers, proportional counters, parallel-plate avalanche counters (PPAC) and microstrip detectors are described. New devices are shown. A description of the processes involved in such detectors is also given. (K.A.) 123 refs.; 25 figs.; 3 tabs

  10. Gamma ray detector optimization for mobile detectors

    International Nuclear Information System (INIS)

    The Energy Research and Development Administration supports a program enabling a rapid response to situations requiring a mobile, detection-at-a-distance capability for locating lost or stolen nuclear materials. For this application, man-portable, vehicular-borne, and airborne detection systems are used. For gamma ray detection, NaI detectors are usually used. Because weight is a serious constraint, many systems employ unshielded detectors. Results of optimization studies to determine a suitable thickness for 12.7 cm diameter NaI detectors that are commonly used in these applications are presented

  11. Hubungan Kejadian Flat Foot dengan Obesitas pada Anak

    OpenAIRE

    Levenia

    2016-01-01

    Introduction. Flat foot is usually occurs and do not cause symptoms in under 5 years old children. But if occur in older children can cause pain even injury in children’s foot. One of flat foot’s risk factor is obesity. Although the prevalence of obesity is increasing every year, research of relationship between obesity and flat foot is still limited. The purpose of this research were to detect prevalence of obesity and flat foot, also to detect the relationship between obesity and flat foot ...

  12. Radiation detectors laboratory

    International Nuclear Information System (INIS)

    The Radiation detectors laboratory was established with the assistance of the International Atomic Energy Agency which gave this the responsibility to provide its services at National and regional level for Latin America and it is located at the ININ. The more expensive and delicate radiation detectors are those made of semiconductor, so it has been put emphasis in the use and repairing of these detectors type. The supplied services by this laboratory are: selection consultant, detectors installation and handling and associated systems. Installation training, preventive and corrective maintenance of detectors and detection systems calibration. (Author)

  13. REVIEW OF PERFORMANCE AND ANALYSIS ISI FLAT PLATE COLLECTOR WITH MODIFIED FLAT PLATE COLLECTOR

    Directory of Open Access Journals (Sweden)

    MR.Y.Y.NANDURKAR

    2012-03-01

    Full Text Available The market of solar water heater of natural circulation type (thermo-siphon is fast growing in India. Initial cost of the solar water heater system at present is high because of store type design. It is necessary to make the product more popular by reducing the cost. This is possible by reducing area of liquid flat plate collector by increasing tube diameter and reducing riser length. Hence it is essential to make solar water heater in affordable range of the general public class. Present work is based on review of comparative performance and analysis of ISI flat plate collector with modified flat plat collector. The paper will be helpful for those who are working in the area of solar water heating system and their use in domestic areas.

  14. Radiation detectors laboratory

    International Nuclear Information System (INIS)

    The National Institute for Nuclear Research has established a Radiation detector laboratory that has the possibility of providing to the consultants on the handling and applications of the nuclear radiation detectors. It has special equipment to repair the radiation detectors used in spectroscopy as the hyper pure Germanium for gamma radiation and the Lithium-silica for X-rays. There are different facilities in the laboratory that can become useful for other institutions that use radiation detectors. This laboratory was created to satisfy consultant services, training and repairing of the radiation detectors both in national and regional levels for Latin America. The laboratory has the following sections: Nuclear Electronic Instrumentation; where there are all kind of instruments for the measurement and characterization of detectors like multichannel analyzers of pulse height, personal computers, amplifiers and nuclear pulse preamplifiers, nuclear pulses generator, aleatories, computer programs for radiation spectra analysis, etc. High vacuum; there is a vacuum escape measurer, two high vacuum pumps to restore the vacuum of detectors, so the corresponding measurers and the necessary tools. Detectors cleaning; there is an anaerobic chamber for the detectors handling at inert atmosphere, a smoke extraction bell for cleaning with the detector solvents. Cryogenic; there are vessels and tools for handling liquid nitrogen which is used for cooling the detectors when they required it. (Author)

  15. Buyers’ Attitude and Preference towards Flat/Apartments

    Directory of Open Access Journals (Sweden)

    R. Renganathan

    2015-04-01

    Full Text Available Nowadays people would like to have and live in their own house. Because of the growing population and lack of sufficient place, cities cannot grow horizontally. Building promoters and contractors in real estate industry are concentrating on the construction of flats/apartments even in cities like Trichy/Tamilnadu. In order to thrive and excel in the competitive environment flat promoters have to understand the expectations, tastes, preferences and lifestyle of the buyers. Two hundred and fifty customers who were living in the flats at Trichy area were included for this study. Findings of this study reveal that people living in the flats are giving importance to location of the flat, price, Swimming pool, Surveillance camera, living space, parking facility, lighting facility, lift and safety. This study will be useful for the customers to express about their opinion with regard to various aspects of flats and also useful for the flat promoters to understand about their buyers.

  16. High-energy detector

    Science.gov (United States)

    Bolotnikov, Aleksey E.; Camarda, Giuseppe; Cui, Yonggang; James, Ralph B.

    2011-11-22

    The preferred embodiments are directed to a high-energy detector that is electrically shielded using an anode, a cathode, and a conducting shield to substantially reduce or eliminate electrically unshielded area. The anode and the cathode are disposed at opposite ends of the detector and the conducting shield substantially surrounds at least a portion of the longitudinal surface of the detector. The conducting shield extends longitudinally to the anode end of the detector and substantially surrounds at least a portion of the detector. Signals read from one or more of the anode, cathode, and conducting shield can be used to determine the number of electrons that are liberated as a result of high-energy particles impinge on the detector. A correction technique can be implemented to correct for liberated electron that become trapped to improve the energy resolution of the high-energy detectors disclosed herein.

  17. Jet Screech Reduction with Perforated Flat Reflector

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In the present experimental study, investigations have been carried out to evaluate the performance of the new control technique of jet screech with different perforated flat reflectors. Mainly two types of porous flat reflectors had been used in the experiment. One reflector (reflector-V) designed for placing the reflector surface vertical to the jet axis, when, another type of reflector (reflector-H) designed for placing the reflecting surface horizontal to the jet axis. In both cases the reflectors had been placed at the nozzle (base tube with uniform cross-sectional area)exit. The diameter of the reflector-V was 15D when the diameter of the reflector-H was 10D. The porous area of the reflector-V was 6D and 4.5D for reflector-H where D indicated the diameter of the nozzle exit. The placement of the reflector at the exit of the nozzle reduces the sound pressure at the nozzle exit. Thus the muted sound can not excite the unstable disturbance at the nozzle exit and the loop of the feedback mechanism disappeared, finally,the generation of jet screech be cancelled. The suction space located at the back side of the porous surface of the reflector-V improves the efficiency of the screech control technique. However, in the case of reflector-H, the receptivity process of feedback loop had been controlled by reducing the disturbances at the effective shock fronts as well as at the nozzle exit. The performance of the proposed method was verified with a flat reflector concept and good performance in jet screech suppression has been confirmed in the case of porous reflector.

  18. Feasibility Study of an Active Sandwich Detector for duel-energy imaging

    International Nuclear Information System (INIS)

    In this study, we investigate a feasibility of sandwich detector based on flat-panel detectors for dual-energy x-ray imaging, particularly for industry application such as a foreign substance detection in noodles. Dual-energy (DE) imaging can remove overlapping background structures that obscure the detection and characterization of target object in radiographs. Although the theoretical framework describing DE imaging had been initialized in the late of 1970s, its renewed interest has been in the spotlight since large area flat-panel detectors capable of real-time imaging with high detective quantum efficiency had been commercially available. DE x-ray imaging based on the fast kVp-switching technique (also known as 'double shot or double-exposure' DE imaging), which acquires low- and high-energy projections in successive exposures, is therefore now available in clinic. Figure 1(a), (b) and (c) show preparations of 'single shot or single-exposure' DE imaging detector, which acquires low- and high-energy projections simultaneously from two detectors arranged in upper and lower layers. Since two detectors are doubly layered, we named it 'the sandwich detector'. While sandwich-detector configurations based on 'passive' film-screen combinations or storage phosphors were often reported, there has not been sufficient attention paid to the use of 'active' solid-state detectors

  19. Feasibility Study of an Active Sandwich Detector for duel-energy imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dongwoon; Han, Jongchul; Kim, Hokyung [Pusan National Univ., Busan, (Korea, Republic of)

    2013-10-15

    In this study, we investigate a feasibility of sandwich detector based on flat-panel detectors for dual-energy x-ray imaging, particularly for industry application such as a foreign substance detection in noodles. Dual-energy (DE) imaging can remove overlapping background structures that obscure the detection and characterization of target object in radiographs. Although the theoretical framework describing DE imaging had been initialized in the late of 1970s, its renewed interest has been in the spotlight since large area flat-panel detectors capable of real-time imaging with high detective quantum efficiency had been commercially available. DE x-ray imaging based on the fast kVp-switching technique (also known as 'double shot or double-exposure' DE imaging), which acquires low- and high-energy projections in successive exposures, is therefore now available in clinic. Figure 1(a), (b) and (c) show preparations of 'single shot or single-exposure' DE imaging detector, which acquires low- and high-energy projections simultaneously from two detectors arranged in upper and lower layers. Since two detectors are doubly layered, we named it 'the sandwich detector'. While sandwich-detector configurations based on 'passive' film-screen combinations or storage phosphors were often reported, there has not been sufficient attention paid to the use of 'active' solid-state detectors.

  20. Geotechnical risk analysis by flat dilatometer (DMT)

    Science.gov (United States)

    Amoroso, Sara; Monaco, Paola

    2015-04-01

    In the last decades we have assisted at a massive migration from laboratory testing to in situ testing, to the point that, today, in situ testing is often the major part of a geotechnical investigation. The State of the Art indicates that direct-push in situ tests, such as the Cone Penetration Test (CPT) and the Flat Dilatometer Test (DMT), are fast and convenient in situ tests for routine site investigation. In most cases the DMT estimated parameters, in particular the undrained shear strength su and the constrained modulus M, are used with the common design methods of Geotechnical Engineering for evaluating bearing capacity, settlements etc. The paper focuses on the prediction of settlements of shallow foundations, that is probably the No. 1 application of the DMT, especially in sands, where undisturbed samples cannot be retrieved, and on the risk associated with their design. A compilation of documented case histories that compare DMT-predicted vs observed settlements, was collected by Monaco et al. (2006), indicating that, in general, the constrained modulus M can be considered a reasonable "operative modulus" (relevant to foundations in "working conditions") for settlement predictions based on the traditional linear elastic approach. Indeed, the use of a site investigation method, such as DMT, that improve the accuracy of design parameters, reduces risk, and the design can then center on the site's true soil variability without parasitic test variability. In this respect, Failmezger et al. (1999, 2015) suggested to introduce Beta probability distribution, that provides a realistic and useful description of variability for geotechnical design problems. The paper estimates Beta probability distribution in research sites where DMT tests and observed settlements are available. References Failmezger, R.A., Rom, D., Ziegler, S.R. (1999). "SPT? A better approach of characterizing residual soils using other in-situ tests", Behavioral Characterics of Residual Soils, B

  1. Flat plate electrohydrodynamic heat pipe experiments

    Energy Technology Data Exchange (ETDEWEB)

    Loehrke, R.I.; Sebits, D.R.

    1975-07-01

    Performance capabilities of electrohydrodynamic (EHD) flat heat pipes were investigated using Freon 113 and Freon 11 as working fluids. All of the pipes employed straight rod electrodes to form axial liquid flow channels and tranverse grooves for capillary surface wetting. Results show: (1) the EHD pipe will prime under load; (2) voltage controlled conductance can be achieved by varying the active area of the evaporator; and (3) the average evaporator conductances measured in these experiments were consistent with those obtained in other experiments with heat pipes of similar surface geometry using the same or similar working fluids.

  2. Evolution of multidimensional flat anisotropic cosmological models

    International Nuclear Information System (INIS)

    We study the dynamics of a flat multidimensional anisotropic cosmological model filled with an anisotropic fluidlike medium. By an appropriate choice of variables, the dynamical equations reduce to a two-dimensional dynamical system. We present a detailed analysis of the time evolution of this system and the conditions of the existence of spacetime singularities. We investigate the conditions under which violent, exponential, and power-law inflation is possible. We show that dimensional reduction cannot proceed by anti-inflation (rapid contraction of internal space). Our model indicates that it is very difficult to achieve dimensional reduction by classical means

  3. Flexible Polyhedral Surfaces with Two Flat Poses

    Directory of Open Access Journals (Sweden)

    Hellmuth Stachel

    2015-05-01

    Full Text Available We present three types of polyhedral surfaces, which are continuously flexible and have not only an initial pose, where all faces are coplanar, but pass during their self-motion through another pose with coplanar faces (“flat pose”. These surfaces are examples of so-called rigid origami, since we only admit exact flexions, i.e., each face remains rigid during the motion; only the dihedral angles vary. We analyze the geometry behind Miura-ori and address Kokotsakis’ example of a flexible tessellation with the particular case of a cyclic quadrangle. Finally, we recall Bricard’s octahedra of Type 3 and their relation to strophoids.

  4. Prunus hybrids rootstocks for flat peach

    OpenAIRE

    Pilar Legua; Jorge Pinochet; María Ángeles Moreno; Juan José Martínez; Francisca Hernández

    2012-01-01

    Peach (Prunus persica L.) is the most important stone fruit tree grown in Spain and is the second most important fruit crop in Europe. The influence of eight Prunus rootstocks (GF-677, Krymsk® 86, PADAC 97-36, PADAC 99-05, PADAC 9912-03, PADAC 0024-01, PAC 0021-01 and PAC 0022-01) on vigor, yield and fruit quality traits of 'UFO 3' flat peach cultivar was studied. The highest trunk cross sectional area was exhibited by GF-677 and the lowest by PADAC 99-05, while intermediate values were found...

  5. Comment on "Conformally flat stationary axisymmetric metrics"

    CERN Document Server

    Barnes, A; Senovilla, José MM

    2003-01-01

    Garcia and Campuzano claim to have found a previously overlooked family of stationary and axisymmetric conformally flat spacetimes, contradicting an old theorem of Collinson. In both these papers it is tacitly assumed that the isometry group is orthogonally transitive. Under the same assumption, we point out here that Collinson's result still holds if one demands the existence of an axis of symmetry on which the axial Killing vector vanishes. On the other hand if the assumption of orthogonal transitivity is dropped, a wider class of metrics is allowed and it is possible to find explicit counterexamples to Collinson's result.

  6. Conformally flat anisotropic spheres in general relativity

    CERN Document Server

    Herrera, L; Ospina, J F; Fuenmayor, E

    2001-01-01

    The condition for the vanishing of the Weyl tensor is integrated in the spherically symmetric case. Then, the resulting expression is used to find new, conformally flat, interior solutions to Einstein equations for locally anisotropic fluids. The slow evolution of these models is contrasted with the evolution of models with similar energy density or radial pressure distribution but non-vanishing Weyl tensor, thereby bringing out the different role played by the Weyl tensor, the local anisotropy of pressure and the inhomogeneity of the energy density in the collapse of relativistic spheres.

  7. Euler angles as torsional flat spaces

    Science.gov (United States)

    Trejo-Mandujano, Hector A.

    In this work we use general tensor calculus to compare the geodesic equation of motion and Newton's first law for force-free classical systems that are described by an arbitrary number of generalized coordinates in spaces with and without torsion. We choose as objects of study the flat torsional Euler angle metric spaces for rigid rotators. We tested the equivalence of the two motion equations using computational software that allowed algebraic manipulation. The main result is that the equivalence only holds for torsion-free spaces, and for isotropic force-free rotators. We present analytical calculations for the isotropic case and computational results for the general case.

  8. Ultrabarrier Flexible Substrates for Flat Panel Displays

    Energy Technology Data Exchange (ETDEWEB)

    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.

  9. The evolution of scintillating medical detectors

    International Nuclear Information System (INIS)

    The principle of scintillation detectors has been among the first realizations of radiation detectors. Despite ongoing attempts to switch to direct converting detectors, scintillators have shown great persistence in the field of medical imaging. In radiography, computer tomography and nuclear medicine, a variety of scintillating devices are the 'workhorses' of the clinician today. For radiography, flat X-ray detectors (FDs) with evaporated scintillation layers are at the level of product introduction. However, X-ray image intensifier tubes (XIIs) are competitive and still have features that will be hard to beat in the near future. Although XIIs have disadvantages, they have experienced a significant evolution in robust image quality and cost reduction over the decades. The so-called 'offline' detectors from film to storage phosphors seemed to have reached a plateau since the late 1970s. However, the distinction between on- and offline may soften in the future, because of new readout concepts. Detectors in computer tomography (CT) have evolved from scintillators to gaseous direct converters back to scintillators. Extreme timing requirements and detector modularity have ruled out designs that would rank as 'high performance' in other fields. Modern ultra-fast ceramic scintillation detectors are a prerequisite of subsecond CT and leave breathing room for future scan times even below 0.5 s. The field of nuclear medicine is a good example of how difficult it is, to replace a cheap and reliable technology. Since many years, direct converters like CdTe and the likes are discussed to overthrow the regime of NaI:Tl in combination with photomultipliers (PMTs). Both components are well known since the 1950s and have shown remarkable staying power. Still the scintillator with the highest light output, NaI:Tl in combination with the basically noiseless PMT is almost unbeatable in low cost. In combination with modern digital electronics, drawbacks of analog circuitry like

  10. Risk, media, and stigma at Rocky Flats

    International Nuclear Information System (INIS)

    Public responses to nuclear technologies are often strongly negative. Events, such as accidents or evidence of unsafe conditions at nuclear facilities, receive extensive and dramatic coverage by the news media. These news stories affect public perceptions of nuclear risks and the geographic areas near nuclear facilities. One result of these perceptions, avoidance behavior, is a form of technological stigma that leads to losses in property values near nuclear facilities. The social amplification of risk is a conceptual framework that attempts to explain how stigma is created through media transmission of information about hazardous places and public perceptions and decisions. This paper examines stigma associated with the US Department of energy's Rocky Flats facility, a major production plant in the nation's nuclear weapons complex, located near Denver, Colorado. This study, based upon newspaper analyses and a survey of Denver area residents, finds that the social amplification theory provides a reasonable framework for understanding the events and public responses that took place in regard to Rocky Flats during a 6-year period, beginning with an FBI raid of the facility in 1989

  11. Maxey Flats in situ waste grouting demonstration

    International Nuclear Information System (INIS)

    The Maxey Flats Disposal Site located in Fleming County, Kentucky was added to the US EPA National Priority List in 1986 and is currently being evaluated for remediation and closure under the CERCLA/Superfund program. The Commonwealth of Kentucky has cosponsored a program with the US DOE Low Level Waste Management Program to demonstrate various remedial technologies which may be applied to source containment at the Maxey Flats site. This paper describes the field demonstration of in-situ waste grouting using a particulate (cement) grout. This demonstration is a follow-on to a similar demonstration using a solution grout. Both programs were designed to develop injection techniques, to assess the ability of the grout to fill the accessible voids within the waste/backfill matrix, to measure the reduction in the hydraulic conductivity of the waste/backfill matrix, and to determine the operational difficulties in implementing a site-wide grouting program. The paper concludes with lessons-learned during the project and estimated costs for full scale implementation

  12. Cosmological consequences of supersymmetric flat directions

    CERN Document Server

    Riva, Francesco; Sarkar, Subir; Giudice, Gian

    In this work we analyze various implications of the presence of large field vacum expectation values (VEVs) along supersymmetric flat direct ions during the early universe. First, we discuss supersymmetric leptogenesis and the grav itino bound. Supersym- metric thermal leptogenesis with a hierarchical right-han ded neutrino mass spectrum normally requires the mass of the lightest right-handed neu trino to be heavier than about 10 9 GeV. This is in conflict with the upper bound on the reheating t empera- ture which is found by imposing that the gravitinos generate d during the reheating stage after inflation do not jeopardize successful nucleosy nthesis. We show that a solution to this tension is actually already incorporated i n the framework, because of the presence of flat directions in the supersymmetric scalar potential. Massive right- handed neutrinos are efficiently produced non-thermally and the observed baryon asymmetry can be explained even for a reheating temperature respecting the grav- itino bound...

  13. Pond fractals in a tidal flat.

    Science.gov (United States)

    Cael, B B; Lambert, Bennett; Bisson, Kelsey

    2015-11-01

    Studies over the past decade have reported power-law distributions for the areas of terrestrial lakes and Arctic melt ponds, as well as fractal relationships between their areas and coastlines. Here we report similar fractal structure of ponds in a tidal flat, thereby extending the spatial and temporal scales on which such phenomena have been observed in geophysical systems. Images taken during low tide of a tidal flat in Damariscotta, Maine, reveal a well-resolved power-law distribution of pond sizes over three orders of magnitude with a consistent fractal area-perimeter relationship. The data are consistent with the predictions of percolation theory for unscreened perimeters and scale-free cluster size distributions and are robust to alterations of the image processing procedure. The small spatial and temporal scales of these data suggest this easily observable system may serve as a useful model for investigating the evolution of pond geometries, while emphasizing the generality of fractal behavior in geophysical surfaces. PMID:26651668

  14. Investigation of the optical fields of flat-spectrum radio sources to faint limiting magnitudes

    International Nuclear Information System (INIS)

    A deep optical survey of the fields of 16 flat-spectrum radio sources has been carried out using the Hale 5-m telescope, with a prototype charge-coupled device as a detector. These sources are members of a complete sample, selected as having S(2.7 GHz) > 1.5 Jy, and were either unidentified, or were identified with very faint objects on the prints of the Palomar Sky Survey. Identifications are found for 12 of these objects; six are galaxies and six are stellar objects. Identifications for the 2.7-GHz sample are therefore now 96 per cent complete, allowing much improved redshift distributions to be derived. Values of V/Vsub(max) for the sample members have also been calculated, with the result that for the flat-spectrum quasars is 0.68, rather than the values nearer 0.5 derived from studies of deeper samples. This result indicates that both the steep-spectrum and flat-spectrum quasars undergo similar degrees of cosmological evolution. (author)

  15. Trophic relationships in tidal flat areas: To what extent are tidal flats dependent on imported food?

    Science.gov (United States)

    Asmus, Harald; Asmus, Ragnhild M.

    In four intertidal areas of 'Königshafen' (island of Sylt, FRG), biomass and production of macrozoobenthos were measured monthly in 1980 and 1984. The areas were characterized by different macrofauna assemblages ( Nereis-Corophium belt, seagrass bed, Arenicola flat and mussel bed). Biomass and production of macrofauna were partitioned with regard to food preference of single species as well as to the food availability within their habitat. In the Nereis-Corophium belt, seagrass bed and the Arenicola flat, most of the secondary production of the macrofauna was formed by grazing animals. Secondary production of mussel beds was nearly 10 times higher than in the other three assemblages. The suspension feeder assemblage depended on planktonic food imported from outside the bay. Considering the secondary production of the total tidal flat area, suspension feeders dominated the other trophic groups, indicating a key position of this group relative to the other macrofaunal assemblages. Mussel beds regulate the seston input to other communities situated further landward. Because of this dominance of the suspension feeder group, the energy and material flow of the total tidal flat is strongly dependent on the seston input from the coastal waters of the North Sea or from other parts of the Wadden Sea.

  16. Unsharpness characteristics of digital detectors for industrial radiographic imaging

    International Nuclear Information System (INIS)

    The investigation of imaging properties of new digital detectors such as imaging plates (used in computed radiography, CR) or flat panels (used as film replacement or in computed tomography, CT) showed energy dependent unsharpness effects. This image unsharpness has essential influences on applications in NDT. Particularly, in CT the precise knowledge of the detector unsharpness characteristics is critical for the evaluation of resulting images in NDT applications. For this reason edge response functions have been determined in dependence on radiation energy as a measure of imaging unsharpness. This analysis reveals a superposition of two distinct unsharpness effects: one effective within a short range (low unsharpness) and another one covering a larger area (high unsharpness). This has considerable consequences to quantitative analysis of unsharpness, as determined either by edge or slit imaging or by MTF calculations. Particularly at lower spatial frequencies the MTF decay is influenced, i. e. the unsharpness is spreading over a larger distance in the X-ray image. At higher spatial frequencies the MTF decay of the detectors does not show any peculiarity. Spatial resolution as measured by line pair or duplex wire IQIs is dominated by the short distance effect. The long distance one can hardly be detected visibly in film images. However, the long range component is clearly measurable for digitised films, for imaging plates and also for flat panel detectors. The long range unsharpness is also one of the major effects, which are responsible for distortions in 3D-CT. MTF and edge response measurements are described for determination of additional unsharpness functions by scattered radiation from material adjacent to the detector layer, e.g. flat panel casings, film and CR cassettes

  17. Virtual detector characterisation with Monte-Carlo simulations

    Science.gov (United States)

    Sukowski, F.; Yaneu Yaneu, J. F.; Salamon, M.; Ebert, S.; Uhlmann, N.

    2009-08-01

    In the field of X-ray imaging flat-panel detectors which convert X-rays into electrical signals, are widely used. For different applications, detectors differ in several specific parameters that can be used for characterizing the detector. At the Development Center X-ray Technology EZRT we studied the question how well these characteristics can be determined by only knowing the layer composition of a detector. In order to determine the required parameters, the Monte-Carlo (MC) simulation program ROSI [J. Giersch et al., Nucl. Instr. and Meth. A 509 (2003) 151] was used while taking into account all primary and secondary particle interactions as well as the focal spot size of the X-ray tube. For the study, the Hamamatsu C9311DK [Technical Datasheet Hamamatsu C9311DK flat panel sensor, Hamamatsu Photonics, ( www.hamamatsu.com)], a scintillator-based detector, and the Ajat DIC 100TL [Technical description of Ajat DIC 100TL, Ajat Oy Ltd., ( www.ajat.fi)], a direct converting semiconductor detector, were used. The layer compositions of the two detectors were implemented into the MC simulation program. The following characteristics were measured [N. Uhlmann et al., Nucl. Instr. and Meth. A 591 (2008) 46] and compared to simulation results: The basic spatial resolution (BSR), the modulation transfer function (MTF), the contrast sensitivity (CS) and the specific material thickness range (SMTR). To take scattering of optical photons into account DETECT2000 [C. Moisan et al., DETECT2000—A Program for Modeling Optical Properties of Scintillators, Department of Electrical and Computer Engineering, Laval University, Quebec City, 2000], another Monte-Carlo simulation was used.

  18. The HERMES recoil detector

    Energy Technology Data Exchange (ETDEWEB)

    Van Hulse, Charlotte, E-mail: charlotte@inwfsun1.UGent.b [Gent University Department of Subatomic and Radiation Physics, Proeftuinstraat 86, 9000 Gent (Belgium)

    2010-11-01

    In order to allow for the detection of low momentum particles, originating from the scattering of a 27.6 GeV lepton beam off a fixed gaseous target at the HERMES experiment at DESY in Hamburg (Germany), a dedicated recoil detector was installed. It consists of a silicon strip detector, located inside the beam vacuum, a scintillating fiber tracker and a photon detector, around a 150 mm long target cell made out of a 75{mu}m thick aluminum tube. The full detector assembly is mounted inside a 1 T super-conducting solenoid and is able to detect protons and pions with momenta up to 1.40 GeV/c and photons in the region surrounding the target cell. The detector has been operational from February 2006 until June 2007. The commissioning and performance of the detector are presented in this paper.

  19. The HERMES Recoil Detector

    Science.gov (United States)

    Kaiser, R.

    2006-07-01

    The HERMES Collaboration is installing a new Recoil Detector to upgrade the spectrometer for measurements of hard exclusive electron/positron scattering reactions, in particular deeply virtual Compton scattering. These measurements will provide access to generalised parton distributions and hence to the localisation of quarks inside hadrons and to their orbital angular momentum. The HERMES Recoil Detector consists of three active components: a silicon detector surrounding the target cell inside the beam vacuum, a scintillating fibre tracker and a photon detector consisting of three layers of tungsten/scintillator. All three detectors are located inside a solenoidal magnetic field of 1 Tesla. The Recoil Detector was extensively tested with cosmic muons over the summer of 2005 and is being installed in the winter of 2005/6 for data taking until summer 2007.

  20. The HERMES Recoil Detector

    International Nuclear Information System (INIS)

    The HERMES Collaboration is installing a new Recoil Detector to upgrade the spectrometer for measurements of hard exclusive electron/positron scattering reactions, in particular deeply virtual Compton scattering. These measurements will provide access to generalised parton distributions and hence to the localisation of quarks inside hadrons and to their orbital angular momentum. The HERMES Recoil Detector consists of three active components: a silicon detector surrounding the target cell inside the beam vacuum, a scintillating fibre tracker and a photon detector consisting of three layers of tungsten/scintillator. All three detectors are located inside a solenoidal magnetic field of 1 Tesla. The Recoil Detector was extensively tested with cosmic muons over the summer of 2005 and is being installed in the winter of 2005/6 for data taking until summer 2007

  1. Intelligent detector design

    International Nuclear Information System (INIS)

    As the complexity and resolution of imaging detectors increases, the need for detailed simulation of the experimental setup also becomes more important. Designing the detectors requires efficient tools to simulate the detector response and reconstruct the events. We have developed efficient and flexible tools for detailed physics and detector response simulation as well as event reconstruction and analysis. The primary goal has been to develop a software toolkit and computing infrastructure to allow physicists from universities and labs to quickly and easily conduct physics analyses and contribute to detector research and development. The application harnesses the full power of the Geant4 toolkit without requiring the end user to have any experience with either Geant4 or C++, thereby allowing the user to concentrate on the physics of the detector system.

  2. Intelligent Detector Design

    International Nuclear Information System (INIS)

    As the complexity and resolution of imaging detectors increases, the need for detailed simulation of the experimental setup also becomes more important. Designing the detectors requires efficient tools to simulate the detector response and reconstruct the events. We have developed efficient and flexible tools for detailed physics and detector response simulation as well as event reconstruction and analysis. The primary goal has been to develop a software toolkit and computing infrastructure to allow physicists from universities and labs to quickly and easily conduct physics analyses and contribute to detector research and development. The application harnesses the full power of the Geant4 toolkit without requiring the end user to have any experience with either Geant4 or C++, thereby allowing the user to concentrate on the physics of the detector system.

  3. Neutrino factory near detector

    OpenAIRE

    Bogomilov, M.; Y. Karadzhov; Matev, R.; Tsenov, R.; Laing, A.; F.J.P. Soler

    2013-01-01

    The neutrino factory is a facility for future precision studies of neutrino oscillations. A so-called near detector is essential for reaching the required precision for a neutrino oscillation analysis. The main task of the near detector is to measure the flux of the neutrino beam. Such a high intensity neutrino source like a neutrino factory provides also the opportunity for precision studies of various neutrino interaction processes in the near detector. We discuss the design concepts of suc...

  4. Study on Silicon detectors

    International Nuclear Information System (INIS)

    Prototypes of Silicon microstrip detectors and Silicon large area detectors (3x2 cm2), realized directly by our group, either by ion implantation or by diffusion are presented. The physical detector characteristics and their performances determined by exposing them to different radioactive sources and the results of extensive tests on passivation, where new technological ways have been investigated, are discussed. The calculation of the different terms contributing to the total dark current is reported

  5. The atlas detector

    International Nuclear Information System (INIS)

    The ATLAS detector, one of the two multi-purpose detectors at the Large Hadron Collider at CERN, is currently being built in order to meet the first proton-proton collisions in time. A description of the detector components will be given, corresponding to the most up to date design and status of construction, completed with test beam results and performances of the first serial modules. (author)

  6. ALFA Detector Control System

    CERN Document Server

    Oleiro Seabra, Luis Filipe; The ATLAS collaboration

    2015-01-01

    ALFA (Absolute Luminosity For ATLAS) is one of the sub-detectors of ATLAS (A Toroidal LHC Apparatus). The ALFA system is composed by four stations installed in the LHC tunnel 240 m away from the ATLAS interaction point. Each station has a vacuum and ventilation system, movement control and all the required electronics for signal processing. The Detector Control System (DCS) provides control and monitoring of several components and ensures the safe operation of the detector contributing to good Data Quality. This paper describes the ALFA DCS system including a detector overview, operation aspects and hardware control through a SCADA system, WinCC OA.

  7. ALFA Detector Control System

    CERN Document Server

    Oleiro Seabra, Luis Filipe; The ATLAS collaboration

    2015-01-01

    ALFA (Absolute Luminosity For ATLAS) is one of the sub-detectors of ATLAS/LHC. The ALFA system is composed by two stations installed in the LHC tunnel 240 m away from each side of the ATLAS interaction point. Each station has a vacuum and ventilation system, movement control and all the required electronic for signal processing. The Detector Control System (DCS) provides control and monitoring of several components and ensures the safe operation of the detector contributing to good Data Quality. This paper describes the ALFA DCS system including a detector overview, operation aspects and hardware control through a SCADA system, WinCC OA.

  8. Detector support head

    International Nuclear Information System (INIS)

    The support head of detectors for densitometric measurements of the regional function of lungs using gamma radiation consists of a group of detectors placed in a common rack. The detectors are placed on holders with adjustable height which allow side movement. The holders are slidably connected to the converging quide rail on the frame via arms. Between the holders and the rack is fitted the drive mechanism consisting of a screw. The design allows the stable adjustment of detectors on the lung field during examination and thereby allows the comparison of results of measurements carried out at different times. (J.B.). 2 figs

  9. Superconducting quantum interference detector

    International Nuclear Information System (INIS)

    The detector is made of a lead foil whose surface is finished with mineral acids. Coiling the foil wh+ch is inductively bonded to a resonance oscillating circuit forms a system of Josephson tunnel contacts. The detector signal was experimentally shown to be many times higher than signals from niobium detectors with point contacts. The detector described is suitable for measuring voltages in the order of 10-14 to 10-15 V, currents of the same order, magnetic fields, etc. (J.B.)

  10. Photocapacitive MIS infrared detectors

    Science.gov (United States)

    Sher, A.; Lu, S. S.-M.; Moriarty, J. A.; Crouch, R. K.; Miller, W. E.

    1978-01-01

    A new class of room-temperature infrared detectors has been developed through use of metal-insulator-semiconductor (MIS) or metal-insulator-semiconductor-insulator-metal (MISIM) slabs. The detectors, which have been fabricated from Si, Ge and GaAs, rely for operation on the electrical capacitance variations induced by modulated incident radiation. The peak detectivity for a 1000-A Si MISIM detector is comparable to that of a conventional Si detector functioning in the photovoltaic mode. Optimization of the photocapacitive-mode detection sensitivity is discussed.

  11. LHCb Detector Performance

    CERN Document Server

    AUTHOR|(CDS)2075808; Adeva, Bernardo; Adinolfi, Marco; Affolder, Anthony; Ajaltouni, Ziad; Akar, Simon; Albrecht, Johannes; Alessio, Federico; Alexander, Michael; Ali, Suvayu; Alkhazov, Georgy; Alvarez Cartelle, Paula; Alves Jr, Antonio Augusto; Amato, Sandra; Amerio, Silvia; Amhis, Yasmine; An, Liupan; Anderlini, Lucio; Anderson, Jonathan; Andreassen, Rolf; Andreotti, Mirco; Andrews, Jason; Appleby, Robert; Aquines Gutierrez, Osvaldo; Archilli, Flavio; Artamonov, Alexander; Artuso, Marina; Aslanides, Elie; Auriemma, Giulio; Baalouch, Marouen; Bachmann, Sebastian; Back, John; Badalov, Alexey; Baesso, Clarissa; Baldini, Wander; Barlow, Roger; Barschel, Colin; Barsuk, Sergey; Barter, William; Batozskaya, Varvara; Battista, Vincenzo; Bay, Aurelio; Beaucourt, Leo; Beddow, John; Bedeschi, Franco; Bediaga, Ignacio; Belogurov, Sergey; Belous, Konstantin; Belyaev, Ivan; Ben-Haim, Eli; Bencivenni, Giovanni; Benson, Sean; Benton, Jack; Berezhnoy, Alexander; Bernet, Roland; Bettler, Marc-Olivier; van Beuzekom, Martinus; Bien, Alexander; Bifani, Simone; Bird, Thomas; Bizzeti, Andrea; Bjørnstad, Pål Marius; Blake, Thomas; Blanc, Frédéric; Blouw, Johan; Blusk, Steven; Bocci, Valerio; Bondar, Alexander; Bondar, Nikolay; Bonivento, Walter; Borghi, Silvia; Borgia, Alessandra; Borsato, Martino; Bowcock, Themistocles; Bowen, Espen Eie; Bozzi, Concezio; Brambach, Tobias; Bressieux, Joël; Brett, David; Britsch, Markward; Britton, Thomas; Brodzicka, Jolanta; Brook, Nicholas; Brown, Henry; Bursche, Albert; Buytaert, Jan; Cadeddu, Sandro; Calabrese, Roberto; Calvi, Marta; Calvo Gomez, Miriam; Campana, Pierluigi; Campora Perez, Daniel; Carbone, Angelo; Carboni, Giovanni; Cardinale, Roberta; Cardini, Alessandro; Carson, Laurence; Carvalho Akiba, Kazuyoshi; Casse, Gianluigi; Cassina, Lorenzo; Castillo Garcia, Lucia; Cattaneo, Marco; Cauet, Christophe; Cenci, Riccardo; Charles, Matthew; Charpentier, Philippe; Chefdeville, Maximilien; Chen, Shanzhen; Cheung, Shu-Faye; Chiapolini, Nicola; Chrzaszcz, Marcin; Ciba, Krzystof; Cid Vidal, Xabier; Ciezarek, Gregory; Clarke, Peter; Clemencic, Marco; Cliff, Harry; Closier, Joel; Coco, Victor; Cogan, Julien; Cogneras, Eric; Cogoni, Violetta; Cojocariu, Lucian; Collazuol, Gianmaria; Collins, Paula; Comerma-Montells, Albert; Contu, Andrea; Cook, Andrew; Coombes, Matthew; Coquereau, Samuel; Corti, Gloria; Corvo, Marco; Counts, Ian; Couturier, Benjamin; Cowan, Greig; Craik, Daniel Charles; Crocombe, Andrew; Cruz Torres, Melissa Maria; Cunliffe, Samuel; Currie, Robert; D'Ambrosio, Carmelo; Dalseno, Jeremy; David, Pascal; David, Pieter; Davis, Adam; De Bruyn, Kristof; De Capua, Stefano; De Cian, Michel; De Miranda, Jussara; De Paula, Leandro; De Silva, Weeraddana; De Simone, Patrizia; Decamp, Daniel; Deckenhoff, Mirko; Del Buono, Luigi; Déléage, Nicolas; Derkach, Denis; Deschamps, Olivier; Dettori, Francesco; Di Canto, Angelo; Dijkstra, Hans; Donleavy, Stephanie; Dordei, Francesca; Dorigo, Mirco; Dosil Suárez, Alvaro; Dossett, David; Dovbnya, Anatoliy; Dreimanis, Karlis; Dujany, Giulio; Dupertuis, Frederic; Durante, Paolo; Dzhelyadin, Rustem; Dziurda, Agnieszka; Dzyuba, Alexey; Easo, Sajan; Egede, Ulrik; Egorychev, Victor; Eidelman, Semen; Eisenhardt, Stephan; Eitschberger, Ulrich; Ekelhof, Robert; Eklund, Lars; El Rifai, Ibrahim; Elsasser, Christian; Ely, Scott; Esen, Sevda; Evans, Hannah Mary; Evans, Timothy; Falabella, Antonio; Färber, Christian; Farinelli, Chiara; Farley, Nathanael; Farry, Stephen; Fay, Robert; Ferguson, Dianne; Fernandez Albor, Victor; Ferreira Rodrigues, Fernando; Ferro-Luzzi, Massimiliano; Filippov, Sergey; Fiore, Marco; Fiorini, Massimiliano; Firlej, Miroslaw; Fitzpatrick, Conor; Fiutowski, Tomasz; Fol, Philip; Fontana, Marianna; Fontanelli, Flavio; Forty, Roger; Francisco, Oscar; Frank, Markus; Frei, Christoph; Frosini, Maddalena; Fu, Jinlin; Furfaro, Emiliano; Gallas Torreira, Abraham; Galli, Domenico; Gallorini, Stefano; Gambetta, Silvia; Gandelman, Miriam; Gandini, Paolo; Gao, Yuanning; García Pardiñas, Julián; Garofoli, Justin; Garra Tico, Jordi; Garrido, Lluis; Gascon, David; Gaspar, Clara; Gauld, Rhorry; Gavardi, Laura; Geraci, Angelo; Gersabeck, Evelina; Gersabeck, Marco; Gershon, Timothy; Ghez, Philippe; Gianelle, Alessio; Gianì, Sebastiana; Gibson, Valerie; Giubega, Lavinia-Helena; Gligorov, Vladimir; Göbel, Carla; Golubkov, Dmitry; Golutvin, Andrey; Gomes, Alvaro; Gotti, Claudio; Grabalosa Gándara, Marc; Graciani Diaz, Ricardo; Granado Cardoso, Luis Alberto; Graugés, Eugeni; Graverini, Elena; Graziani, Giacomo; Grecu, Alexandru; Greening, Edward; Gregson, Sam; Griffith, Peter; Grillo, Lucia; Grünberg, Oliver; Gui, Bin; Gushchin, Evgeny; Guz, Yury; Gys, Thierry; Hadjivasiliou, Christos; Haefeli, Guido; Haen, Christophe; Haines, Susan; Hall, Samuel; Hamilton, Brian; Hampson, Thomas; Han, Xiaoxue; Hansmann-Menzemer, Stephanie; Harnew, Neville; Harnew, Samuel; Harrison, Jonathan; He, Jibo; Head, Timothy; Heijne, Veerle; Hennessy, Karol; Henrard, Pierre; Henry, Louis; Hernando Morata, Jose Angel; van Herwijnen, Eric; Heß, Miriam; Hicheur, Adlène; Hill, Donal; Hoballah, Mostafa; Hombach, Christoph; Hulsbergen, Wouter; Hunt, Philip; Hussain, Nazim; Hutchcroft, David; Hynds, Daniel; Idzik, Marek; Ilten, Philip; Jacobsson, Richard; Jaeger, Andreas; Jalocha, Pawel; Jans, Eddy; Jaton, Pierre; Jawahery, Abolhassan; Jing, Fanfan; John, Malcolm; Johnson, Daniel; Jones, Christopher; Joram, Christian; Jost, Beat; Jurik, Nathan; Kandybei, Sergii; Kanso, Walaa; Karacson, Matthias; Karbach, Moritz; Karodia, Sarah; Kelsey, Matthew; Kenyon, Ian; Ketel, Tjeerd; Khanji, Basem; Khurewathanakul, Chitsanu; Klaver, Suzanne; Klimaszewski, Konrad; Kochebina, Olga; Kolpin, Michael; Komarov, Ilya; Koopman, Rose; Koppenburg, Patrick; Korolev, Mikhail; Kozlinskiy, Alexandr; Kravchuk, Leonid; Kreplin, Katharina; Kreps, Michal; Krocker, Georg; Krokovny, Pavel; Kruse, Florian; Kucewicz, Wojciech; Kucharczyk, Marcin; Kudryavtsev, Vasily; Kurek, Krzysztof; Kvaratskheliya, Tengiz; La Thi, Viet Nga; Lacarrere, Daniel; Lafferty, George; Lai, Adriano; Lambert, Dean; Lambert, Robert W; Lanfranchi, Gaia; Langenbruch, Christoph; Langhans, Benedikt; Latham, Thomas; Lazzeroni, Cristina; Le Gac, Renaud; van Leerdam, Jeroen; Lees, Jean-Pierre; Lefèvre, Regis; Leflat, Alexander; Lefrançois, Jacques; Leo, Sabato; Leroy, Olivier; Lesiak, Tadeusz; Leverington, Blake; Li, Yiming; Likhomanenko, Tatiana; Liles, Myfanwy; Lindner, Rolf; Linn, Christian; Lionetto, Federica; Liu, Bo; Lohn, Stefan; Longstaff, Iain; Lopes, Jose; Lopez-March, Neus; Lowdon, Peter; Lucchesi, Donatella; Luo, Haofei; Lupato, Anna; Luppi, Eleonora; Lupton, Oliver; Machefert, Frederic; Machikhiliyan, Irina V; Maciuc, Florin; Maev, Oleg; Malde, Sneha; Malinin, Alexander; Manca, Giulia; Mancinelli, Giampiero; Mapelli, Alessandro; Maratas, Jan; Marchand, Jean François; Marconi, Umberto; Marin Benito, Carla; Marino, Pietro; Märki, Raphael; Marks, Jörg; Martellotti, Giuseppe; Martens, Aurelien; Martín Sánchez, Alexandra; Martinelli, Maurizio; Martinez Santos, Diego; Martinez Vidal, Fernando; Martins Tostes, Danielle; Massafferri, André; Matev, Rosen; Mathe, Zoltan; Matteuzzi, Clara; Mazurov, Alexander; McCann, Michael; McCarthy, James; McNab, Andrew; McNulty, Ronan; McSkelly, Ben; Meadows, Brian; Meier, Frank; Meissner, Marco; Merk, Marcel; Milanes, Diego Alejandro; Minard, Marie-Noelle; Moggi, Niccolò; Molina Rodriguez, Josue; Monteil, Stephane; Morandin, Mauro; Morawski, Piotr; Mordà, Alessandro; Morello, Michael Joseph; Moron, Jakub; Morris, Adam Benjamin; Mountain, Raymond; Muheim, Franz; Müller, Katharina; Mussini, Manuel; Muster, Bastien; Naik, Paras; Nakada, Tatsuya; Nandakumar, Raja; Nasteva, Irina; Needham, Matthew; Neri, Nicola; Neubert, Sebastian; Neufeld, Niko; Neuner, Max; Nguyen, Anh Duc; Nguyen, Thi-Dung; Nguyen-Mau, Chung; Nicol, Michelle; Niess, Valentin; Niet, Ramon; Nikitin, Nikolay; Nikodem, Thomas; Novoselov, Alexey; O'Hanlon, Daniel Patrick; Oblakowska-Mucha, Agnieszka; Obraztsov, Vladimir; Oggero, Serena; Ogilvy, Stephen; Okhrimenko, Oleksandr; Oldeman, Rudolf; Onderwater, Gerco; Orlandea, Marius; Otalora Goicochea, Juan Martin; Owen, Patrick; Oyanguren, Maria Arantza; Pal, Bilas Kanti; Palano, Antimo; Palombo, Fernando; Palutan, Matteo; Panman, Jacob; Papanestis, Antonios; Pappagallo, Marco; Pappalardo, Luciano; Parkes, Christopher; Parkinson, Christopher John; Passaleva, Giovanni; Patel, Girish; Patel, Mitesh; Patrignani, Claudia; Pearce, Alex; Pellegrino, Antonio; Penso, Gianni; Pepe Altarelli, Monica; Perazzini, Stefano; Perret, Pascal; Perrin-Terrin, Mathieu; Pescatore, Luca; Pesen, Erhan; Pessina, Gianluigi; Petridis, Konstantin; Petrolini, Alessandro; Picatoste Olloqui, Eduardo; Pietrzyk, Boleslaw; Pilař, Tomas; Pinci, Davide; Pistone, Alessandro; Playfer, Stephen; Plo Casasus, Maximo; Polci, Francesco; Poluektov, Anton; Polyakov, Ivan; Polycarpo, Erica; Popov, Alexander; Popov, Dmitry; Popovici, Bogdan; Potterat, Cédric; Price, Eugenia; Price, Joseph David; Prisciandaro, Jessica; Pritchard, Adrian; Prouve, Claire; Pugatch, Valery; Puig Navarro, Albert; Punzi, Giovanni; Qian, Wenbin; Rachwal, Bartolomiej; Rademacker, Jonas; Rakotomiaramanana, Barinjaka; Rama, Matteo; Rangel, Murilo; Raniuk, Iurii; Rauschmayr, Nathalie; Raven, Gerhard; Redi, Federico; Reichert, Stefanie; Reid, Matthew; dos Reis, Alberto; Ricciardi, Stefania; Richards, Sophie; Rihl, Mariana; Rinnert, Kurt; Rives Molina, Vincente; Robbe, Patrick; Rodrigues, Ana Barbara; Rodrigues, Eduardo; Rodriguez Perez, Pablo; Roiser, Stefan; Romanovsky, Vladimir; Romero Vidal, Antonio; Rotondo, Marcello; Rouvinet, Julien; Ruf, Thomas; Ruiz, Hugo; Ruiz Valls, Pablo; Saborido Silva, Juan Jose; Sagidova, Naylya; Sail, Paul; Saitta, Biagio; Salustino Guimaraes, Valdir; Sanchez Mayordomo, Carlos; Sanmartin Sedes, Brais; Santacesaria, Roberta; Santamarina Rios, Cibran; Santovetti, Emanuele; Sarti, Alessio; Satriano, Celestina; Satta, Alessia; Saunders, Daniel Martin; Savrina, Darya; Schiller, Manuel; Schindler, Heinrich; Schlupp, Maximilian; Schmelling, Michael; Schmidt, Burkhard; Schneider, Olivier; Schopper, Andreas; Schune, Marie Helene; Schwemmer, Rainer; Sciascia, Barbara; Sciubba, Adalberto; Semennikov, Alexander; Sepp, Indrek; Serra, Nicola; Serrano, Justine; Sestini, Lorenzo; Seyfert, Paul; Shapkin, Mikhail; Shapoval, Illya; Shcheglov, Yury; Shears, Tara; Shekhtman, Lev; Shevchenko, Vladimir; Shires, Alexander; Silva Coutinho, Rafael; Simi, Gabriele; Sirendi, Marek; Skidmore, Nicola; Skillicorn, Ian; Skwarnicki, Tomasz; Smith, Anthony; Smith, Edmund; Smith, Eluned; Smith, Jackson; Smith, Mark; Snoek, Hella; Sokoloff, Michael; Soler, Paul; Soomro, Fatima; Souza, Daniel; Souza De Paula, Bruno; Spaan, Bernhard; Sparkes, Ailsa; Spradlin, Patrick; Sridharan, Srikanth; Stagni, Federico; Stahl, Marian; Stahl, Sascha; Steinkamp, Olaf; Stenyakin, Oleg; Stevenson, Scott; Stoica, Sabin; Stone, Sheldon; Storaci, Barbara; Stracka, Simone; Straticiuc, Mihai; Straumann, Ulrich; Stroili, Roberto; Subbiah, Vijay Kartik; Sun, Liang; Sutcliffe, William; Swientek, Krzysztof; Swientek, Stefan; Syropoulos, Vasileios; Szczekowski, Marek; Szczypka, Paul; Szumlak, Tomasz; T'Jampens, Stephane; Teklishyn, Maksym; Tellarini, Giulia; Teubert, Frederic; Thomas, Christopher; Thomas, Eric; van Tilburg, Jeroen; Tisserand, Vincent; Tobin, Mark; Tolk, Siim; Tomassetti, Luca; Tonelli, Diego; Topp-Joergensen, Stig; Torr, Nicholas; Tournefier, Edwige; Tourneur, Stephane; Tran, Minh Tâm; Tresch, Marco; Tsaregorodtsev, Andrei; Tsopelas, Panagiotis; Tuning, Niels; Ubeda Garcia, Mario; Ukleja, Artur; Ustyuzhanin, Andrey; Uwer, Ulrich; Vacca, Claudia; Vagnoni, Vincenzo; Valenti, Giovanni; Vallier, Alexis; Vazquez Gomez, Ricardo; Vazquez Regueiro, Pablo; Vázquez Sierra, Carlos; Vecchi, Stefania; Velthuis, Jaap; Veltri, Michele; Veneziano, Giovanni; Vesterinen, Mika; Viaud, Benoit; Vieira, Daniel; Vieites Diaz, Maria; Vilasis-Cardona, Xavier; Vollhardt, Achim; Volyanskyy, Dmytro; Voong, David; Vorobyev, Alexey; Vorobyev, Vitaly; Voß, Christian; de Vries, Jacco; Waldi, Roland; Wallace, Charlotte; Wallace, Ronan; Walsh, John; Wandernoth, Sebastian; Wang, Jianchun; Ward, David; Watson, Nigel; Websdale, David; Whitehead, Mark; Wicht, Jean; Wiedner, Dirk; Wilkinson, Guy; Williams, Matthew; Williams, Mike; Wilschut, Hans; Wilson, Fergus; Wimberley, Jack; Wishahi, Julian; Wislicki, Wojciech; Witek, Mariusz; Wormser, Guy; Wotton, Stephen; Wright, Simon; Wyllie, Kenneth; Xie, Yuehong; Xing, Zhou; Xu, Zhirui; Yang, Zhenwei; Yuan, Xuhao; Yushchenko, Oleg; Zangoli, Maria; Zavertyaev, Mikhail; Zhang, Liming; Zhang, Wen Chao; Zhang, Yanxi; Zhelezov, Alexey; Zhokhov, Anatoly; Zhong, Liang; Zvyagin, Alexander

    2015-01-01

    The LHCb detector is a forward spectrometer at the Large Hadron Collider (LHC) at CERN. The experiment is designed for precision measurements of CP violation and rare decays of beauty and charm hadrons. In this paper the performance of the various LHCb sub-detectors and the trigger system are described, using data taken from 2010 to 2012. It is shown that the design criteria of the experiment have been met. The excellent performance of the detector has allowed the LHCb collaboration to publish a wide range of physics results, demonstrating LHCb's unique role, both as a heavy flavour experiment and as a general purpose detector in the forward region.

  12. Holography of 3D Asymptotically Flat Black Holes

    CERN Document Server

    Fareghbal, Reza

    2014-01-01

    We study the asymptotically flat rotating hairy black hole solution of a three-dimensional gravity theory which is given by taking flat-space limit (zero cosmological constant limit) of New Massive Gravity (NMG). We propose that the dual field theory of the flat-space limit of NMG can be described by a Contracted Conformal Field Theory (CCFT). Using Flat/CCFT correspondence we construct a stress tensor which yields the conserved charges of the asymptotically flat black hole solution. Furthermore, by taking appropriate limit of the Cardy formula in the parent CFT, we find a Cardy-like formula which reproduces the Wald's entropy of the 3D asymptotically flat black hole.

  13. Knitting Force Measurement on Flat Knitting Machines

    Directory of Open Access Journals (Sweden)

    A. Fouda

    2014-01-01

    Full Text Available Knittability can be defined as the ability of yarns to run on knitting machines without problems. Knittability can be achieved when less stress is applied on the knitting machine parts by the knitting yarns. This paper presents a novel measuring system for the knitting force needed to perform knitting yarns on flat knitting machine based on data acquisition system (DAS. The proposed system is used to measure the knitting force at different machine settings and different properties of the knitting yarns to determine the optimal production conditions. For this reason, three types of knitted fabric structures (single jersey, Rib 1 × 1, and full cardigan with three different loop lengths and five different twists of ply yarn were produced. The obtained results showed the optimal yarn ply twist factor (αe which gave minimum knitting force (less stress on needles or knitting yarns at different loop lengths for each structure.

  14. Traversable asymptotically flat wormholes in Rastall gravity

    CERN Document Server

    Moradpour, H

    2016-01-01

    Having introduced the Rastall gravitational theory, and by virtue of the fact that this theory has two unknown parameters, we take the Newtonian limit to define a new parameter for Rastall gravitational theory; a useful dimensionless parameter for simplifying calculations in the Rastall framework. Equipped with basics of the theory, we study the properties of traversable asymptotically flat wormholes in Rastall framework. Then, we investigate the possibility of supporting such geometries by a source with the same state parameter as that of the baryonic matters. Our survey indicates that the parameters of Rastall theory affect the wormhole parameters. It also shows the weak energy condition is violated for all of the studied cases. We then come to investigate the possibility of supporting such geometries by a source of negative energy density and the same state parameter as that of dark energy. Such dark energy-like sources have positive radial and transverse pressures.

  15. A quantum kinematics for asymptotically flat spacetimes

    CERN Document Server

    Campiglia, Miguel

    2014-01-01

    We construct a quantum kinematics for asymptotically flat spacetimes based on the Koslowski-Sahlmann (KS) representation. The KS representation is a generalization of the representation underlying Loop Quantum Gravity (LQG) which supports, in addition to the usual LQG operators, the action of `background exponential operators' which are connection dependent operators labelled by `background' $su(2)$ electric fields. KS states have, in addition to the LQG state label corresponding to 1 dimensional excitations of the triad, a label corresponding to a `background' electric field which describes 3 dimensional excitations of the triad. Asymptotic behaviour in quantum theory is controlled through asymptotic conditions on the background electric fields which label the {\\em states} and the background electric fields which label the {\\em operators}. Asymptotic conditions on the triad are imposed as conditions on the background electric field state label while confining the LQG spin net graph labels to compact sets. We...

  16. Flat tensile specimen design for advanced composites

    Science.gov (United States)

    Worthem, Dennis W.

    1990-01-01

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

  17. Pulsar Magnetospheres: Beyond the Flat Spacetime Dipole

    CERN Document Server

    Gralla, Samuel E; Philippov, Alexander

    2016-01-01

    Most studies of the pulsar magnetosphere have assumed a pure magnetic dipole in flat spacetime. However, recent work suggests that the effects of general relativity are in fact of vital importance and that realistic pulsar magnetic fields may have a significant nondipolar component. We introduce a general analytical method for studying the axisymmetric force-free magnetosphere of a slowly-rotating star of arbitrary magnetic field, mass, radius and moment of inertia, including all the effects of general relativity. We confirm that spacelike current is generically present in the polar caps (suggesting a pair production region), irrespective of the stellar magnetic field. We show that general relativity introduces a ~60% correction to the formula for the dipolar component of the surface magnetic field inferred from spindown. Finally, we show that the location and size of the polar caps can be modified dramatically by even modestly strong higher moments. This can affect emission processes occurring near the star ...

  18. Performance of low-cost X-ray area detectors with consumer digital cameras

    International Nuclear Information System (INIS)

    We constructed X-ray detectors using consumer-grade digital cameras coupled to commercial X-ray phosphors. Several detector configurations were tested against the Varian PaxScan 3024M (Varian 3024M) digital flat panel detector. These include consumer cameras (Nikon D800, Nikon D700, and Nikon D3X) coupled to a green emission phosphor in a back-lit, normal incidence geometry, and in a front-lit, oblique incidence geometry. We used the photon transfer method to evaluate detector sensitivity and dark noise, and the edge test method to evaluate their spatial resolution. The essential specifications provided by our evaluation include discrete charge events captured per mm2 per unit exposure surface dose, dark noise in equivalents of charge events per pixel, and spatial resolution in terms of the full width at half maximum (FWHM) of the detector's line spread function (LSF). Measurements were performed using a tungsten anode X-ray tube at 50 kVp. The results show that the home-built detectors provide better sensitivity and lower noise than the commercial flat panel detector, and some have better spatial resolution. The trade-off is substantially smaller imaging areas. Given their much lower costs, these home-built detectors are attractive options for prototype development of low-dose imaging applications

  19. Rigidity of noncompact complete Bach-flat manifolds

    Science.gov (United States)

    Kim, Seongtag

    2010-04-01

    Let (M,g) be a noncompact complete Bach-flat manifold with positive Yamabe constant. We prove that (M,g) is flat if (M,g) has zero scalar curvature and sufficiently small L2 bound of curvature tensor. When (M,g) has nonconstant scalar curvature, we prove that (M,g) is conformal to the flat space if (M,g) has sufficiently small L2 bound of curvature tensor and L bound of scalar curvature.

  20. Geometric origin of superfluidity in the Lieb lattice flat band

    OpenAIRE

    Julku, Aleksi; Peotta, Sebastiano; Vanhala, Tuomas; Kim, Dong-Hee; Törmä, Päivi

    2016-01-01

    The ground state and transport properties of the Lieb lattice flat band in the presence of an attractive Hubbard interaction are considered. It is shown that the superfluid weight can be large even for an isolated and strictly flat band. Moreover the superfluid weight is proportional to the interaction strength and to the quantum metric, a band structure invariant obtained from the flat-band Bloch functions. These predictions are amenable to verification with ultracold gases and may explain t...

  1. Flat connection, conformal field theory and quantum group

    International Nuclear Information System (INIS)

    General framework of linear first order differential equation for four-point conformal block is studied by using flat connection. Integrability and SL2 invariance restrict possible form of flat connection. Under a special ansatz classical Yang-Baxter equation appears as an integrability condition and the WZW model turns to be unique conformal field theory in that case. Monodromy property of conformal block can be easily determined by the flat connection. 11 refs

  2. Hyperbolic groups have flat-rank at most 1

    CERN Document Server

    Baumgartner, Udo; Willis, George A

    2009-01-01

    The flat-rank of a totally disconnected, locally compact group G is an integer, which is an invariant of G as a topological group. We generalize the concept of hyperbolic groups to the topological context and show that a totally disconnected, locally compact, hyperbolic group has flat-rank at most 1. It follows that the simple totally disconnected locally compact groups constructed by Paulin and Haglund have flat-rank at most 1.

  3. Transverse modes for flat inter-bunch wakes

    CERN Document Server

    Burov, Alexey

    2013-01-01

    If inter-bunch wake fields are flat, i.e. their variations over a bunch length can be neglected, all coherent modes have the same coupled-bunch structure, provided the bunches can be treated as identical by their inner qualities (train theorem). If a flat feedback is strong enough, the transverse modes are single-bunch, provided the inter-bunch wakes are also flat (damper theorem).

  4. TRANSVERSE MODES FOR FLAT INTER-BUNCH WAKES*

    CERN Document Server

    Burov, A

    2013-01-01

    If inter-bunch wake fields are flat, i.e. their variations over a bunch length can be neglected, all coherent modes have the same coupled-bunch structure, provided the bunches can be treated as identical by their inner qualities (train theorem). If a flat feedback is strong enough, the transverse modes are single-bunch, provided the inter-bunch wakes are also flat (damper theorem).

  5. Treatment field specific IMRT QA using flat panel

    International Nuclear Information System (INIS)

    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

  6. Creation Of Constructed Tidal Flats Using Ocean Dredged Sediment

    Science.gov (United States)

    Park, S.; Yi, B.; Lee, I.; Sung, K.

    2007-12-01

    The enforcement of London dumping convention (1972) and protocols (1996) which are comprehensive assessment system for ocean dumping wastes needs environmentally sound treatment and/or reuse of dredged sediment. Creation of constructed tidal flats using dredged sediments could be one of the useful alternatives among other dredged sediment treatments. In this study, the pilot-scale constructed tidal flats with 4 different mixing ratio of ocean dredged sediment were constructed in Nakdong river estuary, Korea. The reed was transplanted from the adjacent reed community after construction, and then the survival and growth rate of the planted reed was measured. Also the changes of Chemical Oxygen Demand (COD), Ignition loss (IL), and the heterotrophic microbial numbers were monitored. The survival rate of the planted reed decreased as the mixing ratio of dredged sediment increased. The survival rate of reed in the constructed tidal flat with 100% dredged sediment was 54% while that in the tidal flat with 0% dredged sediment (original soil of Nakdong river estuary) was 90%. There was little difference of length and diameter of the reed shoot among the 4 different constructed tidal flats. 30% of COD and 9% of IL in the tidal flat with 100% dredged sediment decreased after 202 day, however, the consistent tendency in the change of COD and IL in the other tidal flats was not found possibly due to the open system. It was suggested that the construction of tidal flats using ocean dredged sediment can be possible considering the growth rate of transplanted reeds and the contaminated ocean dredged sediment might be biologically remediated considering the results of decrease of organic matter and increased heterotrophic microbial number in the tidal flat with 100% dredged sediment. However, the continuous monitoring on the vegetation and various environmental factors in the constructed tidal flats should be necessary to evaluate the success of creation of constructed flats using

  7. Rocky Flats Closure Unit Cost Data

    International Nuclear Information System (INIS)

    The Rocky Flats Closure Project has completed the process of stabilizing residual nuclear materials, decommissioning nuclear facilities, remediating environmental media and closing the Rocky Flats Site (Site). The project cost approximately $4.1 B and included the decommissioning of over 700 structures including 5 major plutonium facilities and 5 major uranium facilities, shipping over 14,600 cubic meters of transuranic and 565,000 cubic meters of low level radioactive waste, and remediating a 385-acre industrial area and the surrounding land. Actual costs were collected for a large variety of closure activities. These costs can be correlated with metrics associated with the facilities and environmental media to capture cost factors from the project that could be applicable to a variety of other closure projects both within and outside of the Department of Energy's weapons complex. The paper covers four general topics: the process to correlate the actual costs and metrics, an example of the correlated data for one large sub-project, a discussion of the results, and the additional activities that are planned to correlate and make this data available to the public. The process to collect and arrange the project control data of the Closure Project relied on the actual Closure Project cost information. It was used to correlate these actual costs with the metrics for the physical work, such as building area or waste generated, to support the development of parametric cost factors. The example provides cost factors for the Industrial Sites Project. The discussion addresses the strengths and weaknesses of the data, followed by a section identifying future activities to improve and extend the analyses and integrate it within the Department's Environmental Cost Analysis System. (authors)

  8. Constitution method of flat-band. Harmony played by molecules

    International Nuclear Information System (INIS)

    This paper introduces the constitution method of a tight-binding model where flat-band appears. Firstly, it describes the display of tight-binding model using the second quantization, as well as the constitution of the eigenstate, graph, and hopping matrix. Then, it takes up the flat-band that robustly appears regardless of the details of elements of the hopping matrix, and introduces the constitution method of flat-band for each of bipartite graph and non-bipartite graph. This type of flat-band in the case of bipartite depends on difference in the number of the sites of A sublattice and B sublattice. On the other hand, the flat-band that depends on the details of elements of the hopping matrix appears when the energy levels of molecules embedded on the lattice resonate. The following are described on this type of flat-band: (1) system where rings with magnetic flux that are seemingly not related to flat-band combine, (2) flat-band of decorated square lattice, and (3) relationship between flat-band and localization state. (A.O.)

  9. The ATLAS pixel detector

    OpenAIRE

    Cristinziani, M.

    2007-01-01

    After a ten years planning and construction phase, the ATLAS pixel detector is nearing its completion and is scheduled to be integrated into the ATLAS detector to take data with the first LHC collisions in 2007. An overview of the construction is presented with particular emphasis on some of the major and most recent problems encountered and solved.

  10. ALICE Photon Multiplicity Detector

    CERN Multimedia

    Nayak, T

    2013-01-01

    Photon Multiplicity Detector (PMD) measures the multiplicity and spatial distribution of photons in the forward region of ALICE on a event-by-event basis. PMD is a pre-shower detector having fine granularity and full azimuthal coverage in the pseudo-rapidity region 2.3 < η < 3.9.

  11. The TESLA Detector

    OpenAIRE

    Moenig, Klaus

    2001-01-01

    For the superconducting linear collider TESLA a multi purpose detector has been designed. This detector is optimised for the important physics processes expected at a next generation linear collider up to around 1 TeV and is designed for the specific environment of a superconducting collider.

  12. Alkali ionization detector

    Science.gov (United States)

    Hrizo, John; Bauerle, James E.; Witkowski, Robert E.

    1982-01-01

    A calibration filament containing a sodium-bearing compound is included in combination with the sensing filament and ion collector plate of a sodium ionization detector to permit periodic generation of sodium atoms for the in-situ calibration of the detector.

  13. Borner Ball Neutron Detector

    Science.gov (United States)

    2002-01-01

    The Bonner Ball Neutron Detector measures neutron radiation. Neutrons are uncharged atomic particles that have the ability to penetrate living tissues, harming human beings in space. The Bonner Ball Neutron Detector is one of three radiation experiments during Expedition Two. The others are the Phantom Torso and Dosimetric Mapping.

  14. Drift chamber detectors

    International Nuclear Information System (INIS)

    A review of High Energy Physics detectors based on drift chambers is presented. The ionization, drift diffusion, multiplication and detection principles are described. Most common drift media are analysied, and a classification of the detectors according to its geometry is done. Finally the standard read-out methods are displayed and the limits of the spatial resolution are discussed. (Author)

  15. Pixel detector readout chip

    CERN Multimedia

    1991-01-01

    Close-up of a pixel detector readout chip. The photograph shows an aera of 1 mm x 2 mm containing 12 separate readout channels. The entire chip contains 1000 readout channels (around 80 000 transistors) covering a sensitive area of 8 mm x 5 mm. The chip has been mounted on a silicon detector to detect high energy particles.

  16. ALICE Silicon Strip Detector

    CERN Multimedia

    Nooren, G

    2013-01-01

    The Silicon Strip Detector (SSD) constitutes the two outermost layers of the Inner Tracking System (ITS) of the ALICE Experiment. The SSD plays a crucial role in the tracking of the particles produced in the collisions connecting the tracks from the external detectors (Time Projection Chamber) to the ITS. The SSD also contributes to the particle identification through the measurement of their energy loss.

  17. The LDC detector concept

    Indian Academy of Sciences (India)

    Ties Behnke; LDC Concept Group

    2007-11-01

    In preparation of the experimental program at the international linear collider (ILC), the large detector concept (LDC) is being developed. The main points of the LDC are a large volume gaseous tracking system, combined with high precision vertex detector and an extremely granular calorimeter. The main design force behind the LDC is the particle flow concept.

  18. LHCb detector performance

    NARCIS (Netherlands)

    Aaij, R.; Adeva, B.; Adinol, M.; Affolder, A.; Ajaltouni, Z.; Akar, S.; Albrecht, J.; Alessio, F.; Alexander, M.; Ali, S.; Alkhazov, G.; Alvarez Cartelle, P.; Alves, A. A.; Amato, S.; Amerio, S.; Amhis, Y.; An, L.; Anderlini, L.; Anderson, J.; Andreassen, R.; Andreotti, M.; Andrews, J. E.; Appleby, R. B.; Gutierrez, O. Aquines; Archilli, F.; Artamonov, A.; Artuso, M.; Aslanides, E.; Auriemma, G.; Baalouch, M.; Bachmann, S.; Back, J. J.; Badalov, A.; Baesso, C.; Baldini, W.; Barlow, R. J.; Barschel, C.; Barsuk, S.; Barter, W.; Batozskaya, V.; Battista, V.; Bay, A.; Beaucourt, L.; Beddow, J.; Bedeschi, F.; Bediaga, I.; Belogurov, S.; Belous, K.; Belyaev, I.; Ben-Haim, E.; Bencivenni, G.; Benson, S.; Benton, J.; Berezhnoy, A.; Bernet, R.; Bettler, M. -O.; van Beuzekom, M.; Bien, A.; Bifani, S.; Bird, T.; Bizzeti, A.; Bjornstad, P. M.; Blake, T.; Blanc, F.; Blouw, J.; Blusk, S.; Bocci, V.; Bondar, A.; Bondar, N.; Bonivento, W.; Borghi, S.; Borgia, A.; Borsato, M.; Bowcock, T. J. V.; Bowen, E.; Bozzi, C.; Brambach, T.; Bressieux, J.; Brett, D.; Britsch, M.; Britton, T.; Brodzicka, J.; Brook, N. H.; Brown, H.; Bursche, A.; Buytaert, J.; Cadeddu, S.; Calabrese, R.; Calvi, M.; Calvo Gomez, M.; Campana, P.; Perez, D. Campora; Carbone, A.; Carboni, G.; Cardinale, R.; Cardini, A.; Carson, L.; Akiba, K. Carvalho; Casse, G.; Cassina, L.; Garcia, L. Castillo; Cattaneo, M.; Cauet, Ch.; Cenci, R.; Charles, M.; Charpentier, Ph.; Chefdeville, M.; Chen, S.; Cheung, S. -F.; Chiapolini, N.; Chrzaszcz, M.; Ciba, K.; Vidal, X. Cid; Ciezarek, G.; Clarke, P. E. L.; Clemencic, M.; Cliff, H. V.; Closier, J.; Coco, V.; Cogan, J.; Cogneras, E.; Cogoni, V.; Cojocariu, L.; Collazuol, G.; Collins, P.; Comerma-Montells, A.; Contu, A.; Cook, A.; Coombes, M.; Coquereau, S.; Corti, G.; Corvo, M.; Counts, I.; Couturier, B.; Cowan, G. A.; Craik, D. C.; Crocombe, A. C.; Torres, M. Cruz; Cunliffe, S.; Currie, R.; D'Ambrosio, C.; Dalseno, J.; David, P.; David, P. N. Y.; Davis, A.; De Bruyn, K.; De Capua, S.; De Cian, M.; De Miranda, J. M.; De Paula, L.; De Silva, W.; De Simone, P.; Decamp, D.; Deckenhoff, M.; Del Buono, L.; Deleage, N.; Derkach, D.; Deschamps, O.; Dettori, F.; Di Canto, A.; Dijkstra, H.; Donleavy, S.; Dordei, F.; Dorigo, M.; Dosil Suarez, A.; Dossett, D.; Dovbnya, A.; Dreimanis, K.; Dujany, G.; Dupertuis, F.; Durante, P.; Dzhelyadin, R.; Dziurda, A.; Dzyuba, A.; Easo, S.; Egede, U.; Egorychev, V.; Eidelman, S.; Eisenhardt, S.; Eitschberger, U.; Ekelhof, R.; Eklund, L.; El Rifai, I.; Elsasser, Ch.; Ely, S.; Esen, S.; Evans, H. M.; Evans, T.; Falabella, A.; Faerber, C.; Farinelli, C.; Farley, N.; Farry, S.; Fay, R.; Ferguson, D.; Fernandez Albor, V.; Rodrigues, F. Ferreira; Ferro-Luzzi, M.; Filippov, S.; Fiore, M.; Fiorini, M.; Firlej, M.; Fitzpatrick, C.; Fiutowski, T.; Fol, P.; Fontana, M.; Fontanelli, F.; Forty, R.; Francisco, O.; Frank, M.; Frei, C.; Frosini, M.; Fu, J.; Furfaro, E.; Gallas Torreira, A.; Galli, D.; Gallorini, S.; Gambetta, S.; Gandelman, M.; Gandini, P.; Gao, Y.; Garcia Pardinas, J.; Garofoli, J.; Tico, J. Garra; Garrido, L.; Gascon, D.; Gaspar, C.; Gauld, R.; Gavardi, L.; Geraci, A.; Gersabeck, E.; Gersabeck, M.; Gershon, T.; Ghez, Ph.; Gianelle, A.; Giani, S.; Gibson, V.; Giubega, L.; Gligorov, V. V.; Goebel, C.; Golubkov, D.; Golutvin, A.; Gomes, A.; Gotti, C.; Gandara, M. Grabalosa; Graciani Diaz, R.; Cardoso, L. A. Granado; Grauges, E.; Graverini, E.; Graziani, G.; Grecu, A.; Greening, E.; Gregson, S.; Griffith, P.; Grillo, L.; Gruenberg, O.; Gui, B.; Gushchin, E.; Guz, Yu.; Gys, T.; Hadjivasiliou, C.; Haefeli, G.; Haen, C.; Haines, S. C.; Hall, S.; Hamilton, B.; Hampson, T.; Han, X.; Hansmann-Menzemer, S.; Harnew, N.; Harnew, S. T.; Harrison, J.; He, J.; Head, T.; Heijne, V.; Hennessy, K.; Henrard, P.; Henry, L.; Hernando Morata, J. A.; van Herwijnen, E.; Hess, M.; Hicheur, A.; Hill, D.; Hoballah, M.; Hombach, C.; Hulsbergen, W.; Hunt, P.; Hussain, N.; Hutchcroft, D.; Hynds, D.; Idzik, M.; Ilten, P.; Jacobsson, R.; Jaeger, A.; Jalocha, J.; Jans, E.; Jaton, P.; Jawahery, A.; Jing, F.; John, M.; Johnson, D.; Jones, C. R.; Joram, C.; Jost, B.; Jurik, N.; Kandybei, S.; Kanso, W.; Karacson, M.; Karbach, T. M.; Karodia, S.; Kelsey, M.; Kenyon, I. R.; Ketel, T.; Khanji, B.; Khurewathanakul, C.; Klaver, S.; Klimaszewski, K.; Kochebina, O.; Kolpin, M.; Komarov, I.; Koopman, R. F.; Koppenburg, P.; Korolev, M.; Kozlinskiy, A.; Kravchuk, L.; Kreplin, K.; Kreps, M.; Krocker, G.; Krokovny, P.; Kruse, F.; Kucewicz, W.; Kucharczyk, M.; Kudryavtsev, V.; Kurek, K.; Kvaratskheliya, T.; La Thi, V. N.; Lacarrere, D.; Lafferty, G.; Lai, A.; Lambert, D.; Lambert, R. W.; Lanfranchi, G.; Langenbruch, C.; Langhans, B.; Latham, T.; Lazzeroni, C.; Le Gac, R.; van Leerdam, J.; Lees, J. -P.; Lefevre, R.; Leflat, A.; Lefrancois, J.; Leo, S.; Leroy, O.; Lesiak, T.; Leverington, B.; Li, Y.; Likhomanenko, T.; Liles, M.; Lindner, R.; Linn, C.; Lionetto, F.; Liu, B.; Lohn, S.; Longstaff, I.; Lopes, J. H.; Lopez-March, N.; Lowdon, P.; Lucchesi, D.; Luo, H.; Lupato, A.; Luppi, E.; Lupton, O.; Machefert, F.; Machikhiliyan, I. V.; Maciuc, F.; Maev, O.; Malde, S.; Malinin, A.; Manca, G.; Mancinelli, G.; Mapelli, A.; Maratas, J.; Marchand, J. F.; Marconi, U.; Marin Benito, C.; Marino, P.; Maerki, R.; Marks, J.; Martellotti, G.; Martens, A.; Sanchez, A. Martin; Martinelli, M.; Santos, D. Martinez; Martinez Vidal, F.; Tostes, D. Martins; Massafferri, A.; Matev, R.; Mathe, Z.; Matteuzzi, C.; Mazurov, A.; McCann, M.; McCarthy, J.; McNab, A.; McNulty, R.; McSkelly, B.; Meadows, B.; Meier, F.; Meissner, M.; Merk, M.; Milanes, D. A.; Minard, M. -N.; Moggi, N.; Rodriguez, J. Molina; Monteil, S.; Morandin, M.; Morawski, P.; Morda, A.; Morello, M. J.; Moron, J.; Morris, A. -B.; Mountain, R.; Muheim, F.; Mueller, K.; Mussini, M.; Muster, B.; Naik, P.; Nakada, T.; Nandakumar, R.; Nasteva, I.; Needham, M.; Neri, N.; Neubert, S.; Neufeld, N.; Neuner, M.; Nguyen, A. D.; Nguyen, T. D.; Nguyen-Mau, C.; Nicol, M.; Niess, V.; Niet, R.; Nikitin, N.; Nikodem, T.; Novoselov, A.; O'Hanlon, D. P.; Oblakowska-Mucha, A.; Obraztsov, V.; Oggero, S.; Ogilvy, S.; Okhrimenko, O.; Oldeman, R.; Onderwater, C. J. G.; Orlandea, M.; Goicochea, J. M. Otalora; Owen, P.; Oyanguren, A.; Pal, B. K.; Palano, A.; Palombo, F.; Palutan, M.; Panman, J.; Papanestis, A.; Pappagallo, M.; Pappalardo, L. L.; Parkes, C.; Parkinson, C. J.; Passaleva, G.; Patel, G. D.; Patel, M.; Patrignani, C.; Pearce, A.; Pellegrino, A.; Penso, G.; Altarelli, M. Pepe; Perazzini, S.; Perret, P.; Perrin-Terrin, M.; Pescatore, L.; Pesen, E.; Pessina, G.; Petridis, K.; Petrolini, A.; Picatoste Olloqui, E.; Pietrzyk, B.; Pilar, T.; Pinci, D.; Pistone, A.; Playfer, S.; Casasus, M. Plo; Polci, F.; Poluektov, A.; Polyakov, I.; Polycarpo, E.; Popov, A.; Popov, D.; Popovici, B.; Potterat, C.; Price, E.; Price, J. D.; Prisciandaro, J.; Pritchard, A.; Prouve, C.; Pugatch, V.; Navarro, A. Puig; Punzi, G.; Qian, W.; Rachwal, B.; Rademacker, J. H.; Rakotomiaramanana, B.; Rama, M.; Rangel, M. S.; Raniuk, I.; Rauschmayr, N.; Raven, G.; Redi, F.; Reichert, S.; Reid, M. M.; dos Reis, A. C.; Ricciardi, S.; Richards, S.; Rihl, M.; Rinnert, K.; Rives Molina, V.; Robbe, P.; Rodrigues, A. B.; Rodrigues, E.; Perez, P. Rodriguez; Roiser, S.; Romanovsky, V.; Romero Vidal, A.; Rotondo, M.; Rouvinet, J.; Ruf, T.; Ruiz, H.; Valls, P. Ruiz; Saborido Silva, J. J.; Sagidova, N.; Sail, P.; Saitta, B.; Guimaraes, V. Salustino; Sanchez Mayordomo, C.; Sanmartin Sedes, B.; Santacesaria, R.; Santamarina Rios, C.; Santovetti, E.; Sarti, A.; Satriano, C.; Satta, A.; Saunders, D. M.; Savrina, D.; Schiller, M.; Schindler, H.; Schlupp, M.; Schmelling, M.; Schmidt, B.; Schneider, O.; Schopper, A.; Schune, M. -H.; Schwemmer, R.; Sciascia, B.; Sciubba, A.; Semennikov, A.; Sepp, I.; Serra, N.; Serrano, J.; Sestini, L.; Seyfert, P.; Shapkin, M.; Shapoval, I.; Shcheglov, Y.; Shears, T.; Shekhtman, L.; Shevchenko, V.; Shires, A.; Coutinho, R. Silva; Simi, G.; Sirendi, M.; Skidmore, N.; Skillicorn, I.; Skwarnicki, T.; Smith, N. A.; Smith, E.; Smith, E.; Smith, J.; Smith, M.; Snoek, H.; Sokoloff, M. D.; Soler, F. J. P.; Soomro, F.; Souza, D.; De Paula, B. Souza; Spaan, B.; Sparkes, A.; Spradlin, P.; Sridharan, S.; Stagni, F.; Stahl, M.; Stahl, S.; Steinkamp, O.; Stenyakin, O.; Stevenson, S.; Stoica, S.; Stone, S.; Storaci, B.; Stracka, S.; Straticiuc, M.; Straumann, U.; Stroili, R.; Subbiah, V. K.; Sun, L.; Sutcliffe, W.; Swientek, K.; Swientek, S.; Syropoulos, V.; Szczekowski, M.; Szczypka, P.; Szumlak, T.; T'Jampens, S.; Teklishyn, M.; Tellarini, G.; Teubert, F.; Thomas, C.; Thomas, E.; van Tilburg, J.; Tisserand, V.; Tobin, M.; Tolk, S.; Tomassetti, L.; Tonelli, D.; Topp-Joergensen, S.; Torr, N.; Tournefier, E.; Tourneur, S.; Tran, M. T.; Tresch, M.; Tsaregorodtsev, A.; Tsopelas, P.; Tuning, N.; Garcia, M. Ubeda; Ukleja, A.; Ustyuzhanin, A.; Uwer, U.; Vacca, C.; Vagnoni, V.; Valenti, G.; Vallier, A.; Gomez, R. Vazquez; Vazquez Regueiro, P.; Vazzquez Sierra, C.; Vecchi, S.; Velthuis, J. J.; Veltri, M.; Veneziano, G.; Vesterinen, M.; Viaud, B.; Vieira, D.; Vieites Diaz, M.; Vilasis-Cardona, X.; Vollhardt, A.; Volyanskyy, D.; Voong, D.; Vorobyev, A.; Vorobyev, V.; Voss, C.; de Vries, J. A.; Waldi, R.; Wallace, C.; Wallace, R.; Walsh, J.; Wandernoth, S.; Wang, J.; Ward, D. R.; Watson, N. K.; Websdale, D.; Whitehead, M.; Wicht, J.; Wiedner, D.; Wilkinson, G.; Williams, M. P.; Williams, M.; Wilschut, H. W.; Wilson, F. F.; Wimberley, J.; Wishahi, J.; Wislicki, W.; Witek, M.; Wormser, G.; Wotton, S. A.; Wright, S.; Wyllie, K.; Xie, Y.; Xing, Z.; Xu, Z.; Yang, Z.; Yuan, X.; Yushchenko, O.; Zangoli, M.; Zavertyaev, M.; Zhang, L.; Zhang, W. C.; Zhang, Y.; Zhelezov, A.; Zhokhov, A.; Zhong, L.; Zvyagin, A.

    2015-01-01

    The LHCb detector is a forward spectrometer at the Large Hadron Collider (LHC) at CERN. The experiment is designed for precision measurements of CP violation and rare decays of beauty and charm hadrons. In this paper the performance of the various LHCb sub-detectors and the trigger system are descri

  19. CMS Detector Posters

    CERN Multimedia

    2016-01-01

    CMS Detector posters (produced in 2000): CMS installation CMS collaboration From the Big Bang to Stars LHC Magnetic Field Magnet System Trackering System Tracker Electronics Calorimetry Eletromagnetic Calorimeter Hadronic Calorimeter Muon System Muon Detectors Trigger and data aquisition (DAQ) ECAL posters (produced in 2010, FR & EN): CMS ECAL CMS ECAL-Supermodule cooling and mechatronics CMS ECAL-Supermodule assembly

  20. Delay-line detectors for the UVCS and SUMER instruments on the SOHO Satellite

    Science.gov (United States)

    Siegmund, Oswald H.; Stock, Joseph M.; Marsh, Daniel R.; Gummin, Mark A.; Raffanti, Richard; Hull, Jeffrey; Gaines, Geoffrey A.; Welsh, Barry Y.; Donakowski, B.; Jelinsky, Patrick N.; Sasseen, Timothy; Tom, James L.; Higgins, B.; Magoncelli, T.; Hamilton, Jon W.; Battel, Steven J.; Poland, Arthur I.; Jhabvala, Murzy D.; Sizemore, K.; Shannon, J.

    1994-09-01

    Microchannel plate based detectors with cross delay line image readout have been rapidly implemented for the SUMER and UVCS instruments aboard the Solar Orbiting Heliospheric Observatory (SOHO) mission to be launched in July 1995. In October 1993 a fast track program to build and characterize detectors and detector control electronics was initiated. We present the detector system design for the SOHO UVCS and SUMER detector programs, and results from the detector test program. Two deliverable detectors have been built at this point, a demonstration model for UVCS, and the flight Ly (alpha) detector for UVCS, both of which are to be delivered in the next few weeks. Test results have also been obtained with one other demonstration detector system. The detector format is 26mm x 9mm, with 1024 x 360 digitized pixels,using a low resistance Z stack of microchannel plates (MCP's) and a multilayer cross delay line anode (XDL). This configuration provides gains of approximately equals 2 X 10(superscript 7) with good pulse height distributions (4 X 10(superscript 5) events sec(superscript -1)). Flat field images are dominated by MCP fixed pattern noise and are stable, but the MCP multifiber modulation usually expected is uncharacteristically absent. The detector and electronics have also successfully passed both thermal vacuum and vibration tests.