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Littérature scientifique sur le sujet « X-ray tube current reduction »

Auteur : Grafiati

Publié le 4 juin 2021

Mis à jour le 1 février 2022

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Articles de revues sur le sujet "X-ray tube current reduction"

Vodovatov, A. V. « Evaluation of the dose reduction capabilities in digital radiography of the chest using contrast-detail phantom ». Radiatsionnaya Gygiena = Radiation Hygiene 12, n^o 1 (27 mars 2019) : 62–73. http://dx.doi.org/10.21514/1998-426x-2019-12-1-62-73.

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Assessment of the quality of the images obtained using optimized (low-dose) protocols is the inherent part of the optimization in X-ray diagnostics. To perform the objective quantitative image quality assessment one can use dedicated test-objects, including several components for the simultaneous measurement of the different physical image characteristics (contrast and spatial resolution). The use of such test objects allows estimating and assessing the relations between the patient dose, parameter of the X-ray examination and image quality. That is especially important for the optimization of the digital radiographic examinations performed with automated exposure control. The aim of the current study was to evaluate the possibilities of the patient dose reduction using “contrast-detail” test-object for the digital radiography of the chest in posterior-anterior projection performed with automated exposure control. The study was performed in St-Petersburg Mariinsky hospital on a digital X-ray unit “ARC-Electron” with a flat-panel detector. The combination of a test-object and a tissue-equivalent phantom were imaged on a range of chest X-ray protocols: on a 60–150 kV tube voltage range with automated exposure control; and using fixed 90 kV tube voltage on a range of 2–100 mAs tube current-exposure time product. Dose-area product (cGy×cm2) was measured for each exposure; effective dose (mSv) was estimated for each exposure based on dose-area product. A dedicated software was developed for the automated image quality assessment. The results of the study indicate that the use of a high tube voltage (140–150 kV) with current automated exposure control settings would lead to 60% and 95% reduction of the dose-area product and effective dose, respectively, compared to the standard protocol. The adjustment of the current automated exposure control settings with the reduction of the tube current-exposure time product from 11,2 mAs to the 4,2 mAs for the tube voltage of 90 kV would lead to the reduction of both the dose-area product and effective dose up to a factor of three, compared to the standard protocol. For both scenarios image quality characteristics decreased by less than 15%. The proposed low-dose protocols are under the clinical approbation at Mariinsky hospital. The proposed method of image quality assessment and development of low-dose protocols is recommended for inclusion in the quality assurance program for the radiography examinations.

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FALCINELLI, CRISTINA, ENRICO SCHILEO, FABIO BARUFFALDI, LUCA CRISTOFOLINI et FULVIA TADDEI. « THE EFFECT OF COMPUTED TOMOGRAPHY CURRENT REDUCTION ON PROXIMAL FEMUR SUBJECT-SPECIFIC FINITE ELEMENT MODELS ». Journal of Mechanics in Medicine and Biology 17, n^o 01 (février 2017) : 1750012. http://dx.doi.org/10.1142/s0219519417500129.

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Many studies have addressed the modulation of computed tomography (CT) parameters, and particularly of tube current, to obtain a good compromise between the X-ray dose to the patient and the image quality for diagnostic applications. This study aimed at evaluating the influence of dose reduction by means of tube current reduction on the CT-based subject-specific finite element (FE) modeling. To this aim, CT scans at stepwise reduced values of tube current from 180[Formula: see text]mAs to 80[Formula: see text]mAs were performed on: (i) a densitometric phantom, to quantify the changes in the calibration equation; (ii) a fresh-frozen, water submersed, human cadaver femur, to quantify changes in geometry reconstruction and material mapping from CT, as well as strain prediction accuracy, based on the in vitro strain measurements available; (iii) a fresh-frozen human cadaver thigh with soft tissues attached, to quantify FE results changes in conditions similar to those found in vivo. The results showed that the tube current reduction does not affect the 3D modeling and the femur FE analysis. Our pilot study highlights the possibility of performing CT scans with reduced dose to generate biomechanical models, although a confirmation by performing larger studies with clinical CT data is needed.

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Abbeyquaye, D., S. Inkoom, N. B. Hammond, J. J. Fletcher et B. O. Botwe. « PATIENT DOSE ASSESSMENT AND OPTIMISATION OF PELVIC RADIOGRAPHY WITH COMPUTED RADIOGRAPHY SYSTEMS ». Radiation Protection Dosimetry 195, n^o 1 (juin 2021) : 41–49. http://dx.doi.org/10.1093/rpd/ncab111.

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Abstract Digital radiography systems can reduce radiation dose, this capability was harnessed to explore dose and image quality (IQ) optimisation strategies. Entrance surface dose (ESD), effective dose (ED) and organ doses were determined by the indirect method for patients undergoing pelvic anteroposterior X-ray examinations with computed radiography systems. The IQ of patients’ radiographs was assessed in terms of signal-to-noise ratio (SNR). An anthropomorphic phantom was exposed with varying tube potential (kVp), tube current-time product (mAs), and focus-to-detector distance (FDD) to determine phantom-entrance dose for the optimisation studies. SNR of each phantom radiograph was determined. Patients’ mean ESD of 2.38 ± 0.60 mGy, ED of 0.25 ± 0.07 mSv and SNR of 8.5 ± 2.2 were obtained. After optimisation, entrance dose was reduced by 29.2% with 5 cm increment in FDD, and 5 kVp reduction in tube potential. kVp and/or mAs reduction with an increment in FDD reduced entrance dose without adversely compromising radiographic-IQ.

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Richards, Caryl E., et Daniel R. Obaid. « Low-Dose Radiation Advances in Coronary Computed Tomography Angiography in the Diagnosis of Coronary Artery Disease ». Current Cardiology Reviews 15, n^o 4 (19 août 2019) : 304–15. http://dx.doi.org/10.2174/1573403x15666190222163737.

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Background: Coronary computed tomography angiography (CCTA) is now widely used in the diagnosis of coronary artery disease since it is a rapid, minimally invasive test with a diagnostic accuracy comparable to coronary angiography. However, to meet demands for increasing spatial and temporal resolution, higher x-ray radiation doses are required to circumvent the resulting increase in image noise. Exposure to high doses of ionizing radiation with CT imaging is a major health concern due to the potential risk of radiation-associated malignancy. Given its increasing use, a number of dose saving algorithms have been implemented to CCTA to minimize radiation exposure to “as low as reasonably achievable (ALARA)” without compromising diagnostic image quality. Objective: The purpose of this review is to outline the most recent advances and current status of dose saving techniques in CCTA. Methods: PubMed, Medline, EMBASE and Scholar databases were searched to identify feasibility studies, clinical trials, and technology guidelines on the technical advances in CT scanner hardware and reconstruction software. Results: Sub-millisievert (mSv) radiation doses have been reported for CCTA due to a combination of strategies such as prospective electrocardiogram-gating, high-pitch helical acquisition, tube current modulation, tube voltage reduction, heart rate reduction, and the most recent novel adaptive iterative reconstruction algorithms. Conclusion: Advances in radiation dose reduction without loss of image quality justify the use of CCTA as a non-invasive alternative to coronary catheterization in the diagnosis of coronary artery disease.

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Seifert, H., H. J. Jesberger, G. Schneider, L. Rein, G. Blass, H. G. Limbach, M. Niewald, F. C. Sitzmann et B. Kramann. « Dose reduction in thorax radiography in simulated neonates with additional filtration and digital luminescence radiography ». Acta Radiologica 39, n^o 5 (septembre 1998) : 514–19. http://dx.doi.org/10.1080/02841859809172217.

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Purpose: to determine the minimum acceptable radiation dose for an adequate image quality in thorax a.p. radiographs of neonates using mobile X-ray equipment Material and Methods: the influence of additional filtration (1.0 mm Al+0.1 mm Cu) on image quality and radiation dose was determined for the speed class 400 screen-film system (SFS) and digital luminescence radiography (DLR) by making radiographs of a test phantom. Conventional and digital thorax a.p. radiographs of a rabbit were produced using various tube current-time products. the quality of the rabbit radiographs was judged by eight radiologists applying image quality criteria according to the German guidelines and the recommendations of the European Community Results: the added filter resulted in a dose reduction of 39% at 66 kV. DLR gave a further dose reduction of 25% in comparison to the speed class 400 SFS while maintaining adequate image quality, i. e. the radiographs were clinically acceptable with regard to quality criteria Conclusion: the radiation dose resulting from thorax a.p. radiographs of neonates can be reduced by approximately 50% with the use of additional filtration and DLR

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Pauwels, Ruben, Keith Horner, Jenia Vassileva et Madan M. Rehani. « Thyroid shielding in cone beam computed tomography : recommendations towards appropriate use ». Dentomaxillofacial Radiology 48, n^o 7 (octobre 2019) : 20190014. http://dx.doi.org/10.1259/dmfr.20190014.

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The objective of this paper is to provide recommendations towards the appropriate use of thyroid shielding in dental cone beam CT (CBCT). Based on current evidence of thyroid radiosensitivity, dosimetric data in the presence and absence of shielding, and a depiction of potential adverse effects of thyroid shielding, a concise set of recommendations was prepared. According to current risk models, thyroid sensitivity is particularly high at a young age, and much higher for females. In the literature, involving adult male, female and paediatric reference phantoms, the use of a tightly fitted thyroid collar with a lead-equivalent thickness of at least 0.25 mm has consistently shown a significant reduction (average: 45.9%) of the equivalent dose to the thyroid. It can therefore be recommended that thyroid shielding should be routinely used for children undergoing CBCT scanning and is recommended for adults up to the age of 50. The increase of the X-ray tube current from automatic exposure control systems due to thyroid shielding can be avoided by placing the shielding collar after acquiring the scout images. Should real-time tube current modulation be implemented in dental CBCT imaging in the future, perspectives regarding the appropriate use of shielding may change according to current trends in CT. In view of the manifestation of metal artefacts, shielding is best avoided if radiological evaluation of tissues below the lower border of the mandible is needed.

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Seifitokaldani, A., M. Perrier et O. Savadogo. « Oxygen Reduction Reaction (ORR) on a Mixed Titanium and Tantalum Oxy-nitride Catalyst Prepared by the Urea-based Sol-gel Method ». Journal of New Materials for Electrochemical Systems 17, n^o 2 (9 mai 2014) : 055–65. http://dx.doi.org/10.14447/jnmes.v17i2.424.

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The electrochemical stability and activity of different compositions of titanium and tantalum oxy-nitride nano-catalysts were investigated for the oxygen reduction reaction (ORR). A new sol-gel method was used to produce a nano-powder mixture of Ti and Ta oxynitride from their alkoxides using urea as a nitrogen source. The precursors prepared by the sol-gel method were annealed in a N2 + 3% H2 atmosphere at determined temperatures (500, 700 and 900 °C) inside a silica tube furnace. X-ray diffraction results proved that by using this method a considerable amount of nitrogen was inserted into the catalyst structure at a relatively low temperature. Energy dispersive spectroscopy showed that the prepared catalyst should be oxidized carbonitride of titanium and/or tantalum. Heat treatment had a major effect on the onset potential by changing the crystallinity of the catalyst, so that the onset potential of titanium oxynitride increased from ca. 0.05 V to 0.65 V vs. NHE by increasing the temperature from 500 to 700 °C. Increasing the Ta concentration also led to a higher onset potential but lower ORR current. For instance, the onset potential for the ORR for tantalum oxynitride heat treated at 700 °C was ca. 0.85 V vs. NHE while this value was ca. 0.65 V vs. NHE for titanium oxynitride. However, the ORR current was 100 times smaller in tantalum oxynitride, most likely because of a low electrochemically active surface area. Electrochemical measurements suggested that an appropriate composition of titanium and tantalum was required to have both a good onset potential and ORR current by improving the catalytic activity and increasing the active surface area and electrical conductivity.

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Jakobs, Tobias F., Christoph R. Becker, Bernd Ohnesorge, Thomas Flohr, Christoph Suess, Uwe J. Schoepf et Maximilian F. Reiser. « Multislice helical CT of the heart with retrospective ECG gating : reduction of radiation exposure by ECG-controlled tube current modulation ». European Radiology 12, n^o 5 (21 février 2002) : 1081–86. http://dx.doi.org/10.1007/s00330-001-1278-x.

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Kamyshanskaya, I. G., V. M. Cheremisin, A. V. Vodovatov et A. N. Boriskina. « Results of the clinical evaluation of the low-dose protocols of the digital linear tomography of the chest ». Radiatsionnaya Gygiena = Radiation Hygiene 13, n^o 1 (31 mars 2020) : 47–59. http://dx.doi.org/10.21514/1998-426x-2020-13-1-47-59.

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High levels of tuberculosis morbidity in the Russian Federation lead to the extensive use of X-ray diagnostics for the tuberculosis screening and assessment of the effectiveness of treatment. Digital radiography and computed tomography are traditionally used for the diagnostics of tuberculosis. These methods are associated with significant drawbacks: low specificity for radiography, high costs per examination, significant patient doses, and limited availability for computed tomography. As an additional method for the assessment of the effectiveness of the tuberculosis treatment it is possible to use linear tomography performed on the digital X-ray units. The aim of the current study was to evaluate the possibility of utilization of the digital linear tomography for the control of the effectiveness of tuberculosis treatment in a dedicated antitubercular medical facility. The study was divided in two stages. The first stage was aimed at the assessment of the diagnostic image quality of the digital linear tomograms obtained using the previously developed low-dose imaging protocols. Image quality assessment was performed using an anthropomorphic chest phantom and dedicated imitators of the lung lesions. Image quality was assessed by the experts (radiologists) based on the developed image quality criteria. Results of the first stage of the study indicate that all low-dose protocols allow obtaining images with at least acceptable image quality. Hence it was possible to propose low-dose protocols for clinical evaluations. The second stage of the study was performed as a prospective cohort survey aimed at the evaluation of the structure of X-ray examinations, patient doses and clinical image quality of the digital linear tomograms in antitubercular early treatment center. The cohort survey included two patient samples, uniform by age and gender composition, anthropometric characteristics and structure of diagnosis. One of the samples was imaged using standard (vendor) digital linear protocols, other – using the proposed low-dose protocols. Dose data collection (measurement of dose-area product and subsequent calculation of effective dose) and expert image quality assessment was performed for each patient. The results of the second stage of the study indicate that the use of the low-dose protocols allow reducing the patient effective doses per examination up to a factor of 6–8 (0.56 – 5.9 mSv for standard protocols; 0.2 – 1.15 mSv for low-dose protocols) due to the reduction in tube current-time product (126 mean mAs and 11 mean mAs, respectively). The dose reduction is accompanied by the reduction in the image quality of the linear tomograms (from “excellent” or “good” for standard protocols to “acceptable” for low-dose protocols). However, that dose not hinder the conclusion decision and identification of pathologies. Results of the study indicate that digital linear tomography can be used for the evaluation of the dynamics of the pathological process in the lungs with the previously defined localization of the pathology. The presented low-dose protocols were implemented into radiological practice of the antitubercular early treatment center. Currently, the proposed low-dose protocols are under evaluation for the large-scale study on the base of general practice hospitals

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Kupferer, Astrid, Michael Mensing, Jan Lehnert, Stephan Mändl et Stefan Mayr. « Carbon and Neon Ion Bombardment Induced Smoothing and Surface Relaxation of Titania Nanotubes ». Nanomaterials 11, n^o 9 (21 septembre 2021) : 2458. http://dx.doi.org/10.3390/nano11092458.

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Titania nanotube arrays with their enormous surface area are the subject of much attention in diverse fields of research. In the present work, we show that not only 60 keV and 150 keV ion bombardment of amorphous titania nanotube arrays yields defect creation within the tube walls, but it also changes the surface morphology: the surface relaxes and smoothens in accordance with a curvature-driven surface material’s transport mechanism, which is mediated by radiation-induced viscous flow or radiation-enhanced surface diffusion, while the nanotubes act as additional sinks for the particle surface currents. These effects occur independently of the ion species: both carbon and neon ion bombardments result in comparable surface relaxation responses initiated by an ion energy of 60 keV at a fluence of 1 × 1016 ions/cm2. Using atomic force microscopy and contact angle measurements, we thoroughly study the relaxation effects on the surface topography and surface free energy, respectively. Moreover, surface relaxation is accompanied by further amorphization in surface-near regions and a reduction in the mass density, as demonstrated by Raman spectroscopy and X-ray reflectivity. Since ion bombardment can be performed on global and local scales, it constitutes a versatile tool to achieve well-defined and tunable topographies and distinct surface characteristics. Hence, different types of nanotube arrays can be modified for various applications.

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Thèses sur le sujet "X-ray tube current reduction"

Gerstenmaier, Jan Frank. « Public health implications of medical diagnostic radiation exposure ». Diss., 2012. http://hdl.handle.net/10500/6085.

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Radiation from Computed Tomography (CT) is now the major contributor to population radiation dose. Despite controversy around the dose-effect relationship of radiation from CT, the linear non-threshold (LNT) theory is endorsed by many authorities, and constitutes the basis of cancer risk estimates. The purpose of this study was (1) a literature review of radiobiological theories, and methods of dose saving stategies in CT; (2) to highlight the importance of dose saving in CT, and to demonstrate how dose can be saved in a radiology department: Following a 40% reduction in reference X-ray tube current for a CT of the urinary tract, the effecitve dose and estimated lifetime attributable risk of incident cancer due to this CT in a group (n=103) were reduced by 37% and 38% in an age and sex-matched group respectively. The literature review showed that the public health implications of CT radiation exposure remain uncertain.
Health Studies
M.A. (Public Health)

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Chapitres de livres sur le sujet "X-ray tube current reduction"

« was gathered in one stack, it would occupy a space of 1.25 m3, the size of a small office desk. AECL deposited and Nordion deposits radioactive waste material at their Chalk River disposal site. For transport from the supplier to the user (and back to the supplier when most of the source strength is exhausted) ^C o and I37Cs are shipped in special steel casks. These are designed to survive severe traffic accidents, fire, or other disasters. In order to minimize corrosion of cobalt pins or cesium capsules in the irradiation facility, the water of the source storage pool is constantly recirculated through a deionizer. A sensitive radiation monitor close to the deionizer is used to detect any radioactivity in case the water should be contaminated by a leak in the source. Nordion estimated in 1991 that 17 MCi of 60Co was in service worldwide, installed in 170 irradiators in 45 countries. Many of these facilities have been in operation for more than 20 years. They are mostly used for radiation sterilization of medical disposables, and only in some countries are they also used for irradiation of foodstuffs. Details on the design of various types of gamma irradiation facilities can be found in a number of review articles and book chapters ( -). Some of the earliest systematic studies on food irradiation were carried out with x-ray machines. X-rays are produced when matter is bombarded by electrons of sufficiently high kinetic energy. An x-ray tube (Fig. 5) consists basically of an evacuated glass bulb containing a wire filament which can be heated and opposite it a piece of metal, usually tungsten, which can be cooled. The filament is given a negative charge (cathode) and the metal a positive charge (anode, or anticathode). When the cathode filament is heated by passing an electric current through it, it emits electrons. When these hit the anode, x-rays are produced. The anode must be cooled because in a typical x-ray tube about 99% of the energy carried by the electrons may be converted to heat, and only about % appears in the form of ». Dans Safety of Irradiated Foods, 36–37. CRC Press, 1995. http://dx.doi.org/10.1201/9781482273168-28.

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Actes de conférences sur le sujet "X-ray tube current reduction"

Luo, Weitao, et Xu Wang. « Abnormal Acoustic Noise Reduction in X-Ray Tube Single-Phase Motor ». Dans 2009 2nd International Conference on Biomedical Engineering and Informatics. IEEE, 2009. http://dx.doi.org/10.1109/bmei.2009.5304871.

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Chipiga, L. A., A. V. Vodovatov, T. V. Grigorieva et L. A. Ivanova. « Evaluation of tube current modulation programs for the optimization of chest computed tomography protocols ». Dans 6TH INTERNATIONAL CONFERENCE ON X-RAY, ELECTROVACUUM AND BIOMEDICAL TECHNIQUE. AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0013272.

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Obodovskiy, A. V., V. B. Bessonov et I. A. Larionov. « Temperature deflection of the anode part of x-ray tube with imposition anode during tomography ». Dans CURRENT TRENDS IN RENEWABLE AND ALTERNATE ENERGY. Author(s), 2019. http://dx.doi.org/10.1063/1.5095744.

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Jeong, Taewon, Do-Yoon Kim, Shanghyeun Park, Ilhwan Kim et YongChurl Kim. « Modyfying device structure for high emission current for x-ray tube application from triode-type carbon nanotube cathode ». Dans 2012 25th International Vacuum Nanoelectronics Conference (IVNC). IEEE, 2012. http://dx.doi.org/10.1109/ivnc.2012.6316905.

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Choi, Sungyoul, Jun-Tae Kang, Jin-Woo Jeong, Jae-Woo Kim, Seungjoon Ahn et Yoon-Ho Song. « Advanced active-current control for fast and stable operation of a carbon nanotube field-emission X-ray tube ». Dans 2014 IEEE International Vacuum Electronics Conference (IVEC). IEEE, 2014. http://dx.doi.org/10.1109/ivec.2014.6857724.

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Berliner, Leonard, Kui-Ming Chen, Shenq-Rong Hwang, Alfonso Buffa, Martin Darms et Andrew Jeffries. « Preliminary evaluation of transmission x-ray tube system with a flat-detector DR system : image quality and dose reduction ». Dans SPIE Medical Imaging, sous la direction de Robert M. Nishikawa et Bruce R. Whiting. SPIE, 2013. http://dx.doi.org/10.1117/12.2003232.

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Agazar, Mohamed, Denis Perrillat, Hanane Saadeddine, Christophe Robert, Laurence Casteignau et Dominique Fortune. « Study of non-invasive instruments for the measurement of pulsed X-ray high voltage tube ». Dans 19th International Congress of Metrology (CIM2019), sous la direction de Sandrine Gazal. Les Ulis, France : EDP Sciences, 2019. http://dx.doi.org/10.1051/metrology/201902002.

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Non-invasive instruments (kVp meters) are widely used in radiology with diagnostic and guidance systems. Placed in the x-ray beam, they combine detectors and filters, to determine X-ray tube voltage and exposure time, which are the most important quantities in radiology and diagnostic quality control. Calibration of these instruments were limited by reference bench capabilities. General Electric Medical System France and LNE (The national metrology institute in France) have developed a reference bench for the characterization of kVp meters. The set up includes a fast high voltage generator associated with its internal measuring systems and an X-ray tube. The measurements are compared with an invasive reference standard. The set-up is installed in a Faraday cage, precautions have been taken in order to carry out accurate measurements and special adaptations have been made to avoid stray capacitances, which affect the dynamic performance of the generator. Results have shown a good agreement with the internal measuring system of the generator but the kVp meters have shown both good and bad results depending the exposure time, the current and the positioning.

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Calderón-Colón, Xiomara, et Otto Zhou. « Development of Carbon Nanotube Field Emitters for X-Ray Source ». Dans ASME 2007 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2007. http://dx.doi.org/10.1115/sbc2007-175998.

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Carbon Nanotubes (CNTs) have been shown excellent field emission emitters due to their unique properties. CNTs are a stable form of carbon; a graphite sheet rolls up forming a cylindrical shape with high aspect ratio, low turn-on field, high current density, high strength (1) and can generate quality x-ray radiation (2). These properties make carbon nanotubes very attractive for field emission applications. Field emission cathodes are the central part of field emission displays (FED) and carbon nanotubes field emission x-ray source. FED is a new flat panel display technology; this technology enables much thinner, lighter, and highest resolution displays than the cathode ray tubes (CRT). CNTs field emission x-ray source technology has applications in medical imaging and homeland security (2–7). The current thermionic cathodes have several disadvantages over CNT based field emission x-ray source such as slow response time, high power consumption, high operation temperature that reduces the lifetime of the x-ray tube (4) and large device size (3). Also CNT based field emission x-ray source offers improvement in high temporal resolution and capabilities for spatial and temporal modulation (7). CNT field emission x-ray source technology is available in single- and multi-beam imaging system. Multi-beam imaging system offers image of an object from multiple projection angles without mechanical motion (7).

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Russ, M., A. Shankar, S. V. Setlur Nagesh, C. N. Ionita, D. R. Bednarek et S. Rudin. « Focal spot size reduction using asymmetric collimation to enable reduced anode angles with a conventional angiographic x-ray tube for use with high resolution detectors ». Dans SPIE Medical Imaging, sous la direction de Thomas G. Flohr, Joseph Y. Lo et Taly Gilat Schmidt. SPIE, 2017. http://dx.doi.org/10.1117/12.2253724.

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Sasabe, Takashi, Shohji Tsushima, Shuichiro Hirai, Katsunori Minami et Keiji Yada. « Liquid Water Visualization in an Operating PEMFC by Soft X-Ray Radiography ». Dans ASME 2009 7th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2009. http://dx.doi.org/10.1115/fuelcell2009-85135.

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Liquid water distribution in the operational PEMFC was visualized by soft X-ray radiography. To achieve a maximum sensitivity towards liquid water, low electron beam energy in soft X-ray range was chosen. As a result, the spatial resolution of 1 μm and the temporal resolution of 0.5 sec were obtained. In addition, a correlation between the accumulation of water and the reduction of performance in higher current density range was observed. At low current densities, liquid water accumulation was observed under the ribs, because the longer diffusion length for the rib area conduced to a less effective water removal into the vapor phase. With increase of current density, liquid water was also observed under the channels and the reduction of performance with time was observed. These results suggested that the current density under the rib is much less than under the channel and the anisotropy of GDL and the geometry of flow field had a heavy impact on the liquid water distribution and the cell performance.

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