Articles de revues : « X-ray tube current reduction »

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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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Dahlman, P., L. Jangland, M. Segelsjö et A. Magnusson. « Optimization of computed tomography urography protocol, 1997 to 2008 : Effects on radiation dose ». Acta Radiologica 50, n^o 4 (mai 2009) : 446–54. http://dx.doi.org/10.1080/02841850902821757.

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Background: Since computed tomography (CT) urography began to replace excretory urography as the primary imaging technique in uroradiology, the collective radiation dose to the patients has increased. Purpose: To examine the changes in the CT urography protocol for investigating suspected urinary tract malignancy between the years 1997 and 2008, and how these changes have influenced the mean effective dose. Material and Methods: The study was based on 102 patients (mean age 66.1±14.8 years, range 31–89 years; 30 female, 72 male) divided into five groups (groups A–E) corresponding to the time points at which changes were made to the CT urography protocol. The mean effective doses were estimated using the ImPACT CT Patient Dosimetry Calculator. Results: The number of scan phases at CT urography was reduced from four to three in 1999, resulting in a reduction of the mean effective dose from 29.9/22.5 (female [F]/male [M]) mSv (group A) to 26.1/18.9 (F/M) mSv (group B). In 2001, mAs settings were adapted to patient size, and the mean effective dose was reduced to 16.8/12.0 (F/M) mSv (group C). In 2005, scans were performed with a multidetector-row CT equipped with automatic tube current modulation in the x- and y-axis (CARE Dose). The effective mAs was also lowered in the unenhanced and excretory phase, yet the mean effective dose increased to 18.2/13.1 (F/M) mSv (group D), since the effective mAs had to be increased in the corticomedullary phase to maintain image quality. In 2008, as tube current modulation in the x-, y-, and z-axis was introduced (CARE Dose4D), the mean effective dose was reduced to 11.7/8.8 (F/M) mSv (group E). Conclusion: This study shows that the individual mean effective dose to patients undergoing CT urography has decreased by 60%, from 29.9/22.5 (F/M) mSv in 1997 to 11.7/8.8 (F/M) mSv in 2008.

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Atherton, J. V., et E. L. Nickoloff. « Noninvasive x-ray tube current measurement ». Medical Physics 14, n^o 2 (mars 1987) : 258–61. http://dx.doi.org/10.1118/1.596080.

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Sano, Richard R. « X‐ray tube noise and vibration reduction ». Journal of the Acoustical Society of America 98, n^o 6 (décembre 1995) : 3026. http://dx.doi.org/10.1121/1.413836.

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Stolyarov, I. N. « Reduction of the Working Temperature of X-Ray Tube Bearings ». Biomedical Engineering 46, n^o 5 (janvier 2013) : 206–8. http://dx.doi.org/10.1007/s10527-013-9306-0.

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Stern, Christoph, Stefan Sommer, Christoph Germann, Julien Galley, Christian W. A. Pfirrmann, Benjamin Fritz et Reto Sutter. « Pelvic bone CT : can tin-filtered ultra-low-dose CT and virtual radiographs be used as alternative for standard CT and digital radiographs ? » European Radiology 31, n^o 9 (12 mars 2021) : 6793–801. http://dx.doi.org/10.1007/s00330-021-07824-x.

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Abstract Objectives To compare ultra-low-dose CT (ULD-CT) of the osseous pelvis with tin filtration to standard clinical CT (CT), and to assess the quality of computed virtual pelvic radiographs (VRs). Methods CT protocols were optimized in a phantom and three pelvic cadavers. Thirty prospectively included patients received both standard CT (automated tube voltage selection and current modulation) and tin-filtered ULD-CT of the pelvis (Sn140kV/50mAs). VRs of ULD-CT data were computed using an adapted cone beam–based projection algorithm and were compared to digital radiographs (DRs) of the pelvis. CT and DR dose parameters and quantitative and qualitative measures (1 = worst, 4 = best) were compared. CT and ULD-CT were assessed for osseous pathologies. Results Dose reduction of ULD-CT was 84% compared to CT, with a median effective dose of 0.38 mSv (quartile 1–3: 0.37–0.4 mSv) versus 2.31 mSv (1.82–3.58 mSv; p < .001), respectively. Mean dose of DR was 0.37 mSv (± 0.14 mSv). The median signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of bone were significantly higher for CT (64.3 and 21.5, respectively) compared to ULD-CT (50.4 and 18.8; p ≤ .01), while ULD-CT was significantly more dose efficient (figure of merit (FOM) 927.6) than CT (FOM 167.6; p < .001). Both CT and ULD-CT were of good image quality with excellent depiction of anatomy, with a median score of 4 (4–4) for both methods (p = .1). Agreement was perfect between both methods regarding the prevalence of assessed osseous pathologies (p > .99). VRs were successfully calculated and were equivalent to DRs. Conclusion Tin-filtered ULD-CT of the pelvis at a dose equivalent to standard radiographs is adequate for assessing bone anatomy and osseous pathologies and had a markedly superior dose efficiency than standard CT. Key Points • Ultra-low-dose pelvic CT with tin filtration (0.38 mSv) can be performed at a dose of digital radiographs (0.37 mSv), with a dose reduction of 84% compared to standard CT (2.31 mSv). • Tin-filtered ultra-low-dose CT had lower SNR and CNR and higher image noise than standard CT, but showed clear depiction of anatomy and accurate detection of osseous pathologies. • Virtual pelvic radiographs were successfully calculated from ultra-low-dose CT data and were equivalent to digital radiographs.

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Sharma, Anju, Preeth Sivakumar, Andrew Feigel, In Tae Bae, Lawrence P. Lehman, Joseph Gregor, James Cash et Joseph Kolly. « Effects of x-ray exposure on NOR and NAND flash memories during high-resolution 2D and 3D x-ray inspection ». International Symposium on Microelectronics 2016, n^o 1 (1 octobre 2016) : 000660–65. http://dx.doi.org/10.4071/isom-2016-thp53.

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Abstract In this paper, we present a detailed study on the effects of x-ray exposure on data corruption in commercially available NOR and NAND flash memory devices during x-ray inspection with a high-resolution Phoenix Nanomex system from GE. We investigated role of the x-ray tube voltage, tube current, device orientation, x-ray filters and photon energy. We explored the low exposure regime in detail when the first byte errors start occurring and also determined the absorbed dose for 100% byte errors. No data corruption was observed after the normal 2D x-ray inspection and CT scans of the NOR and NAND flash memory devices under study. However, increase in the tube voltage, tube current and/or the x-ray beam size resulted in byte errors which increased exponentially with the exposure time. The byte error rate was found to be much more sensitive to the tube voltage than the tube current. It was also affected by the device orientation with respect to the x-ray beam. The NAND flash memories were found to be more susceptible to data corruption from x-ray exposure than the NOR devices examined in this work. Some NOR devices were irradiated with the monochromatic x-rays from the CHESS synchrotron facility at Cornell University. Of all the photon energies used in this study, 12 keV x-ray irradiation resulted in the highest byte error rate. In this paper, we thus present a direct proof that it is the low-energy photon absorption that plays a major role in introducing bit errors in flash memories. Commonly available low-energy x-ray filters such as Cu and Al foils were found to be effective in preventing data corruption in such devices for long exposure time. Use of lower tube voltage, lower tube current, smaller x-ray spot size, short exposure time and low-energy x-ray filters, is recommended to prevent data corruption during 2D and 3D x-ray inspection of flash memory devices and other semiconductor devices in general.

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He, W., W. Huda, D. Magill, E. Tavrides et H. Yao. « X-ray tube current modulation and patient doses in chest CT ». Radiation Protection Dosimetry 143, n^o 1 (9 novembre 2010) : 81–87. http://dx.doi.org/10.1093/rpd/ncq291.

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Oseberg, Mikael, Vanessa Tran, Kim Hoang, Hilde Lauvhaug et Hung Thai Phero Nguyen. « CT Thorax lavdose - En sammenligning av et organdosemodulerings program X-CARE og vismut beskyttelse ». Radiography Open 3, n^o 1 (31 mars 2017) : 10. http://dx.doi.org/10.7577/radopen.1996.

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InnledningComputertomografi (CT) er en hyppig utført undersøkelse i Norge. Både mammae og thyroidea er strålefølsomme organer som eksponeres ved en CT thorax undersøkelse. For å få ned inngangsdosen (ESD) til slike strålefølsomme organer kan man enten benytte seg av en organspesifikk adaptiv dose reduksjons protokoll (X-CARE) eller isteden legge vismut beskyttelse over de strålefølsomme organene ved CT-undersøkelsen. I denne studien sammenligner vi huddosen (ESD) over mamma, samt bildekvalitet, ved bruk av disse to metodene ved en CT thorax lavdose undersøkelse?Material og metode30 spiral skanninger, hvorav ti standard lavdose, ti med vismut beskyttelse og ti med X-CARE, ble utført på et Alderson fantom, kombinert med Care Dose 4D, på en Siemens SOMATOM Definition Edge 128 CT maskin. ESD ble målt, CTDIvol og Dose-lengde-produkt (DLP) ble hentet ut fra doserapporten. Den objektive bildekvaliteten ble analysert, og vurdert ved hjelp av tre Region Of Interest (ROI), plassert hhv i luft, i lungeparenkymet og i pleura parietale. Signal til støyforhold (SNR) og kontrast til støyforhold (CNR) ble regnet ut ifra ROI verdiene.ResultaterESD til mamma viste dosereduksjon sammenlignet med en standard CT thorax lavdose; hhv 16,5 % dosereduksjon ved bruk av vismut beskyttelse, og 0,44 % ved X-CARE. Det var ingen forskjell i CTDIvol og DLP ved standard lavdose skanningen eller skanningen med vismut beskyttelse. Skanningen med X-CARE ga en økning i CTDIvol og DLP på omtrent 12 %. SNR og CNR i lungeparenkymet og pleura parietale var høyest ved standard lavdose undersøkelsen. Bildestøyen økte 48 % ved vismut og 26,4 % ved X-CARE.KonklusjonESD ble markant redusert ved CT thorax lavdose undersøkelsen med vismut beskyttelse, men ga samtidig en markant økning i bildestøyen. X-CARE reduserte ESD minimalt sammenlignet med standard lavdose skanningen, men ga økt bildestøy. Den mest effektive måten å oppnå en optimal lavdose undersøkelse på, er ved å utføre en standard CT thorax lavdose protokoll. AbstractIntroductionComputed tomography (CT) is a frequent examination conducted in Norway. Mammae and thyroid gland are both dose sensitive body organs, which are being exposed during a thoracic CT examination. Therefore, an optimization of protocols is necessary and X-CARE (organ-based tube current modulation) or bismuth protection may be applied during a CT examination. Will the two methods give a difference in the entrance surface dose (ESD) to mamma and the image quality of a low-dose thoracic CT examination?Materials and methodsThirty spiral CT scans of which ten was standard low-dose, ten with bismuth shielding and ten with X-CARE was performed on an Alderson phantom, combined with CARE Dose 4D and carried out on a Siemens SOMATOM Definition Edge 128. Measures as ESD, CTDIvol and Dose-length-product (DLP) were obtained from the dose report. The image quality was analysed objectively and assessed using three Region of Interest (ROI), placed in air, lung parenchyma and parietal pleura. Signal to noise ratio (SNR) and contrast to noise ratio (CNR) were calculated from the ROI results.ResultsESD to the mammary gland demonstrated a dose reduction compared to a standard thoracic CT low dose. Respectively; 16.5 % dose reduction with bismuth shielding and 0.44 % with X-CARE. There was no difference in CTDIvol and DLP between the standard low-dose scans and the scans with bismuth shielding. The CT scans with X-CARE gave an increase in CTDIvol and DLP by approximately 12 %. SNR and CNR in the lung parenchyma and parietal pleura were highest during the standard low-dose scans. Bismuth shielding increased the noise with 48 % and X-CARE with 26,4 %.ConclusionESD was significantly reduced during the CT thoracic low-dose examination using bismuth shielding, however notably the bismut increased the image noise. X-CARE reduced the ESD minimally compared to the CT low-dose scans, and it also increased the image noise. The most efficient way to achieve an optimal thoracic CT examination is to use a standard low-dose protoco

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Kunimura, Shinsuke, Yugo Sugawara et Shumpei Kudo. « Reduction of Spectral Interference between X-ray Peaks Originating from an X-ray Tube and X-ray Fluorescence Peaks in Total Reflection X-ray Fluorescence Analysis ». ISIJ International 57, n^o 5 (2017) : 953–55. http://dx.doi.org/10.2355/isijinternational.isijint-2016-729.

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Kim, Sung-Chul. « Feasibility of Using the Clamp Meter in Measuring X-Ray Tube Current ». International Journal of Contents 9, n^o 1 (28 mars 2013) : 38–41. http://dx.doi.org/10.5392/ijoc.2013.9.1.038.

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Miyake, Syusaku, Yujiro Suzuki, yuji Aoki et Nobutoshi Sato. « 374 Development of X-ray Analyzer with function of tube current measurement ». Japanese Journal of Radiological Technology 51, n^o 10 (1995) : 1444. http://dx.doi.org/10.6009/jjrt.kj00001353145.

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Katoh, Yoh, Hitoshi Sato, Toru Negishi, Kuniko Takagi, Shinji Abe et Izumi Ogura. « X-ray Spectrum Calculated from Dynamic Data (Tube Voltege and Current Values) ». Japanese Journal of Radiological Technology 52, n^o 2 (1996) : 216. http://dx.doi.org/10.6009/jjrt.kj00001354138.

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Matsubara, K., H. Koshida, T. Takata, J. Horii, H. Iida, K. Koshida, O. Matsui et A. Fukuda. « SU-D-217BCD-02 : Online Angular Tube Current Modulation in X-Ray Computed Tomography : Can Tube Current Be Modulated Appropriately ? » Medical Physics 39, n^o 6Part3 (juin 2012) : 3619. http://dx.doi.org/10.1118/1.4734693.

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Nazemi, Ehsan, Nathanaël Six, Domenico Iuso, Björn De Samber, Jan Sijbers et Jan De Beenhouwer. « Monte-Carlo-Based Estimation of the X-ray Energy Spectrum for CT Artifact Reduction ». Applied Sciences 11, n^o 7 (1 avril 2021) : 3145. http://dx.doi.org/10.3390/app11073145.

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Beam hardening and scattering effects can seriously degrade image quality in polychromatic X-ray CT imaging. In recent years, polychromatic image reconstruction techniques and scatter estimation using Monte Carlo simulation have been developed to compensate for beam hardening and scattering CT artifacts, respectively. Both techniques require knowledge of the X-ray tube energy spectrum. In this work, Monte Carlo simulations were used to calculate the X-ray energy spectrum of FleXCT, a novel prototype industrial micro-CT scanner, enabling beam hardening and scatter reduction for CT experiments. Both source and detector were completely modeled by Monte Carlo simulation. In order to validate the energy spectra obtained via Monte Carlo simulation, they were compared with energy spectra obtained via a second method. Here, energy spectra were calculated from empirical measurements using a step wedge sample, in combination with the Maximum Likelihood Expectation Maximization (MLEM) method. Good correlation was achieved between both approaches, confirming the correct modeling of the FleXCT system by Monte Carlo simulation. After validation of the modeled FleXCT system through comparing the X-ray spectra for different tube voltages inside the detector, we calculated the X-ray spectrum of the FleXCT X-ray tube, independent of the flat panel detector response, which is a prerequisite for beam hardening and scattering CT artifacts.

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CHIDA, KOICHI, TATSUO NAGASAKA, HIROKI ISHIYA, HIROYUKI SATO, MASAHIRO SAI et MASATOSHI SASAKI. « Accuracy of a Monitoring Unit for X-ray Tube Voltage and Current in X-ray High-Voltage Generator ». Japanese Journal of Radiological Technology 53, n^o 2 (1997) : 265–71. http://dx.doi.org/10.6009/jjrt.kj00003109745.

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Sakurai, Kenji. « New Rotating Anode X-Ray Generator For XAFS Experiments ». Advances in X-ray Analysis 39 (1995) : 149–53. http://dx.doi.org/10.1154/s0376030800022552.

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A high-power X-ray generator equipped with a lanthanum hexaboride cathode has been developed for X-ray absorption fine structure experiments. A high tube-current of more than 1,000 mA can be provided when operated at low tube-voltage of less than 20 kV. In addition, the focal width is narrow enough (less than 0.1 mm) to ensure good energy resolution. Extremely intense monochromatic X-rays (106 ∼ 107 counts/(sec.mm2) at the sample position), which are completely free from higher order harmonics and tungsten contamination lines, are available, when a Johansson-type spectrometer is employed. The filament life has been significantly prolonged by the high vacuum specification of the tube.

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An, Mou, et Yaoqin Xie. « A Novel CT Imaging System with Adjacent Double X-Ray Sources ». Computational and Mathematical Methods in Medicine 2013 (2013) : 1–6. http://dx.doi.org/10.1155/2013/391212.

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Current computed tomography (CT) scanners rotate fast to reduce motion artifact. X-ray tube must work in a high power to make the image clear under short exposure time. However, the life span of such a tube may be shortened. In this paper, we propose a novel double sources CT imaging system, which puts two of the same X-ray sources closely with each other. The system is different from current dual source CT with orthogonal X-ray sources. In our system, each projection is taken twice by these two sources to enhance the exposure value and then recovered to a single source projection for image reconstruction. The proposed system can work like normal single source CT system, while halving down the working power for each tube.

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Odeh, Ahmad Sharief. « The reduction of Si diodes dark current for X-ray dosimetry ». Radiation Physics and Chemistry 44, n^o 1-2 (juillet 1994) : 57–59. http://dx.doi.org/10.1016/0969-806x(94)90103-1.

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Kubota, Hideaki, Yoshiaki Ozaki, Masao Matsumoto et Hitoshi Kanamori. « Effects of x-ray tube-voltage ripple and current mode on patient dose ». Medical Physics 20, n^o 4 (juillet 1993) : 1023–28. http://dx.doi.org/10.1118/1.596999.

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Timofeev, G. A., N. N. Potrakhov et A. Yu Gryaznov. « Data Transmission in the X-Ray Emission Frequency Range of Electromagnetic Radiation ». Journal of the Russian Universities. Radioelectronics 24, n^o 2 (29 avril 2021) : 6–17. http://dx.doi.org/10.32603/1993-8985-2021-24-2-6-17.

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Introduction. Data transmission systems using the X-ray frequency range of electromagnetic radiation – X-ray communication system (XCS) have a number of advantages in comparison with radio or optical communication systems. The most significant advantages for practical use are their higher stealth and external interferences resistance, as well as stability against interception and decryption. It is of importance to develop a method for calculating the main parameters of an X-ray communication system: the range and speed of data transmission. In addition, the construction design and results of experimental research of the current X-ray communication system should be provided.Aim. To develop physical and technical foundations of data transmission systems using the X-ray frequency range of electromagnetic radiation.Materials and methods. We used an original method of calculating the X-ray emission spectrum, taking into account the attenuation coefficient in the propagation medium.Results. A technique for data transmission using the X-ray frequency range of electromagnetic radiation was suggested, including a method for calculating basic parameters e.g. the transmission range and speed, as well as the construction design of the current X-ray communication system model. Relations between these parameters and the operating modes of the X-ray tube were shown. The calculated and experimental data were in good agreement, sufficient for practical use. On their basis, it can be expected that at a voltage across the X-ray tube of 200 kV and the tube current of 1A in a 1-μs pulse, data transmission range in free air will be about 250 m. The maximum possible data transmission rate when using the developed X-ray tube will be 5 Mbit/s.Conclusions. The results of analytical and experimental investigations showed that the range and rate of data transmission of the XCS are exclusively determined by the transmitter energetic capabilities: by voltage and average the X-ray tube current during the generation of packages (series) of the X-ray pulses, as well as by the duration of a single X-ray pulse. It is concluded that the prospects of XCS depend on the development of specialized X-ray sources generating a series of pulses with the minimum possible duration of every single pulse in a series. Taking into account the specific features, XCS can become an alternative to conventional radio and optical systems for communication and navigation.

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Parsons, D., et J. Robar. « OC-0159 : X-ray tube current modulation with dynamic blade collimation for CBCT guidance ». Radiotherapy and Oncology 119 (avril 2016) : S73—S74. http://dx.doi.org/10.1016/s0167-8140(16)31408-6.

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Zuhaira Ismail, Farrah, Mohamad Nidzam Rahmat et Norishahaini M. Ishak. « A Study on Absorption Coefficient of Sustainable Acoustic Panels from Rice Husks and Sugarcane Baggase ». Advanced Materials Research 1113 (juillet 2015) : 198–203. http://dx.doi.org/10.4028/www.scientific.net/amr.1113.198.

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Noise has detrimental effects on human lives and it is a nuisance to the environment. As many of the available sound reduction materials in the current market are hazardous, there are demands for alternative sustainable materials to reduce the noise problem. Therefore, the aim of this research is to study the potential of using an agricultural waste as sound absorption panel. For the purpose of this study, the combination of two materials was under studied; rice husks and sugarcane baggase. There were two main objective of the research; first is to develop absorption panels from the combination of rice husks and sugarcane baggase at different percentage of mixture. Second objective is to identify the absorption rate of the panels. The study encompasses the fabrication of the sustainable sound panels using the rice husk and sugarcane fibre and bond using Phenol formaldehyde (PF). Five panels of sized 12 inch x 12 inch and 12 mm thick were fabricated. The absorption coefficient of the samples was done at the acoustic lab, Faculty of Engineering & Build Environment, Universiti Kebangsaan Malaysia (UKM), Bangi. The panels were tested using an impedance tube. The procedure of the test was carried out in accordance with ISO 10534-2:1998 standards. Based on the results, sample 1 gave the highest absorption coefficient compared to sample 2, 3, 4 and 5. It can be concluded that the acoustic panel made from a mixture of 100% rice husks had higher absorption co-efficient compared to the performance of the other samples given the fact that the characteristic of the rice husks which has air gap in every single piece of rice husk. The spongy properties of the sample 1 panel has created many void spaces which encouraged more sound absorption capability due to the porous surface of the panel. Sound absorption is very much affected by the availability of porosity level of the panel. Thus, further studies on other potential materials from waste should be conducted.Keywords. Noise, Agriculture waste, sound, absorption panels, absorption co-efficient

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Kanematsu, Masayuki, Hiroshi Kondo, Toshiharu Miyoshi, Satoshi Goshima, Yoshifumi Noda, Yukichi Tanahashi et Kyongtae T. Bae. « Whole-body CT with high heat-capacity X-ray tube and automated tube current modulation—Effect of tube current limitation on contrast enhancement, image quality and radiation dose ». European Journal of Radiology 84, n^o 5 (mai 2015) : 877–83. http://dx.doi.org/10.1016/j.ejrad.2015.01.019.

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Bryant, Keith, et Ragnar Vaga. « Recent Advances in X-ray for Semicon Applications ». International Symposium on Microelectronics 2019, n^o 1 (1 octobre 2019) : 000573–83. http://dx.doi.org/10.4071/2380-4505-2019.1.000573.

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Abstract Taking x-ray images goes back over 100 years. Since then, there have been numerous advances in x-ray technology and these have been increasingly applied in helping the manufacturing of electronic components and assemblies, as well as in their failure analysis. Most recently, this has been rapidly driven by the reduction in device and feature size and the movement to using newer, lower density materials within the structures, such as copper wire replacing gold wire as the interconnection material of choice within components. Another driver for developments is the engineering of single 3D packages with multiple chips stacked vertically one on top of the other, which results in smaller and more efficient packaging of devices. In order to meet these challenges and those in the future, there have been a number of recent key improvements to the vital components within x-ray systems. The choice of available technologies, however, means selecting the tube/detector combination, which is optimum for a particular electronics inspection application, is no longer so clear-cut. For example, one configuration may provide certain benefits that are applicable for one area of electronics inspection, whilst being less valid for others. This paper will review the various x-ray tube and detector types that are available and explain the implications of these choices for electronics inspection in terms of what they provide for inspection regarding image resolution, magnification, tube power, detector pixel size and the effects of detector radiation damage, amongst others. This paper will also look in detail at the capabilities of high end CT systems to inspect wafer bumps, copper pillars and TSV's, new designs are reducing key dimensions of all of these interconnections challenging x-ray systems to produce clear images.

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Belev, G., et S. O. Kasap. « Reduction of the dark current in stabilized a-Se based X-ray detectors ». Journal of Non-Crystalline Solids 352, n^o 9-20 (juin 2006) : 1616–20. http://dx.doi.org/10.1016/j.jnoncrysol.2005.11.086.

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Alkhazishvili, Alexander V., Yuri N. Potrakhov, Aleksandr S. Misyurin, Alexandr V. Vodovatov et Aleksey Y. Skripnik. « А mobile microfocal x-ray diagnostic complex in the imaging of premature newborns ». Journal of Clinical Practice 12, n^o 2 (23 juillet 2021) : 30–38. http://dx.doi.org/10.17816/clinpract65148.

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Background: In the modern clinical practice, providing fast, mobile and high-quality bedside X-ray imaging is important for managing newborn children . Thus, the development of new devices with all these features and their clinical application are of considerable significance. Aims: Estimation of the diagnostic capabilities of a microfocal X-ray diagnostic complex for the imaging of premature newborns. Methods: The study was performed at the facilities of Almazov National Medical Research Centre. The study included X-ray examinations of 156 premature newborns using the method of microfocus radiography: 139 X-ray images of the chest, 17 X-ray images of the abdomen. The imaging was performed using the projection magnification technique with a patient positioned close to the X-ray source. Results: The microfocal X-ray images showed the necessary quality for the diagnosis of pathological changes in the chest and abdomen in infants. The patient dose estimation was based on the radiation output of the X-ray unit and the tube current-time product. For the maximum values of the tube voltage, tube current and exposure time, the effective doses did not exceed 0.02 mSv, corresponding to the negligible radiation risk category. Conclusions: Microfocal radiography allows performing informative X-ray examinations of premature newborns, especially using the projection magnification technique. The use of a microfocal X-ray diagnostic complex allows reducing patient doses, increasing the mobility and usability of the X-ray equipment. The first experience of clinical application of microfocal radiography in neonatology and pediatrics with the projection magnification of an X-ray image was found successful. The implementation of this device in pediatric clinical practice will optimize the tactics of managing premature newborns.

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Zhan, Xiaohong, Xing Bu, Tao Qin, Haisong Yu, Jie Chen et Yanhong Wei. « X-ray online detection for laser welding T-joint of Al–Li alloy ». Modern Physics Letters B 31, n^o 14 (18 mai 2017) : 1750154. http://dx.doi.org/10.1142/s0217984917501548.

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In order to detect weld defects in laser welding T-joint of Al–Li alloy, a real-time X-ray image system is set up for quality inspection. Experiments on real-time radiography procedure of the weldment are conducted by using this system. Twin fillet welding seam radiographic arrangement is designed according to the structural characteristics of the weldment. The critical parameters including magnification times, focal length, tube current and tube voltage are studied to acquire high quality weld images. Through the theoretical and data analysis, optimum parameters are settled and expected digital images are captured, which is conductive to automatic defect detection.

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Fajrin, Hanifah Rahmi, Zaipul Rahmat et Djoko Sukwono. « Kilovolt Peak Meter Design as a Calibrator of X-Ray Machine ». International Journal of Electrical and Computer Engineering (IJECE) 9, n^o 4 (1 août 2019) : 2328. http://dx.doi.org/10.11591/ijece.v9i4.pp2328-2335.

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This research aimed to design the KvP meter for checking the error of output voltage from X-Ray machine with the range of 50-70 KvP. It used Arduino Gelatino microcontroller programmed with Arduino IDE software as data processor of detector result. The detector was designed based on the physics principle using material attenuation coefficient namely aluminum whose good effect in reducing the energy level of X-ray photons. Thus, the photodiode sensor only read the effective energy of the X-ray energy. Based on the radiation intensity ratio through the aluminum filter with 0.25 mm and 0.5 mm thickness, it is better to measure X-ray tube voltage non-invasively The KvP Meter was tested by setting duration of X-ray exposure that was 0.3 second, tube current was 10 mA, and KvP Meter distance from collimator was 90 cm. A prototype unit was made, and the performance was tested in terms of error and precision. After testing and analyzing the data, the error result was less than 5.1% with the highest measurement precision of ± 1.50. It is generally concluded that this equipment can be used to measure the voltage of the X-ray tube.

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Hassan, Fatiheea F. « Assessment of X-Ray Tube Technical Factors : Tube Voltage and Exposure Time in Erbil Medical Imaging Centers ». Disease and Diagnosis 9, n^o 4 (30 décembre 2020) : 144–47. http://dx.doi.org/10.34172/ddj.2020.03.

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Background: An evaluation of certain radiographic factors affecting patient exposure during medical imaging was carried out. Factors considered included selection of tube kilovoltage and time exposure combination. An increase in X-ray tube voltage increases the amount of radiation coming out of the X-ray tube, as well as the amount of skin dose in the image. This study aimed to assess the possibility of reducing the voltage and exposure time in medical imaging centers. The study indeed intended to protect patients from the risk of developing cancer with excessive radiation dose. Materials and Methods: This study was performed in Erbil hospitals, Iraq. NOMEX multimeter (Finland, PTW) was used to measure radiation dose (mGy), total voltage, current (mA), exposure time (s), and total filtration in 150 patients undergoing different X-ray examinations. Results: The results showed that the highest output was obtained in the age group of 42-70 years (dose range: 52.43–19.46 mGy), followed by the age group of 50-70 years (dose range: 39.9–25.63 mGy) and the age group of 10–40 years (dose range: 30.35–10.55 mGy). Conclusion: The high voltage (kVp) and high exposure time to be important factors to increase patient doses via increasing the exposure dose. Thus, optimization of exposure time and voltage is recommended for all cancer patients undergoing medical imaging with high voltage and long exposure time.

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Jiang, Ming, Christopher Lee Wyatt et Ge Wang. « X-Ray Phase-Contrast Imaging with Three 2D Gratings ». International Journal of Biomedical Imaging 2008 (2008) : 1–8. http://dx.doi.org/10.1155/2008/827152.

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X-ray imaging is of paramount importance for clinical and preclinical imaging but it is fundamentally restricted by the attenuation-based contrast mechanism, which has remained essentially the same since Roentgen's discovery a century ago. Recently, based on the Talbot effect, groundbreaking work was reported using 1D gratings for X-ray phase-contrast imaging with a hospital-grade X-ray tube instead of a synchrotron or microfocused source. In this paper, we report an extension using 2D gratings that reduces the imaging time and increases the accuracy and robustness of phase retrieval compared to current grating-based phase-contrast techniques. Feasibility is demonstrated via numerical simulation.

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Chida, K., T. Nagasaka, M. Sai, H. Satoh, T. Shimizu, A. Honma et M. Sasaki. « 375 Accuracy of monitoring unit of tube voltage and current in X-ray high voltage generator ». Japanese Journal of Radiological Technology 51, n^o 10 (1995) : 1445. http://dx.doi.org/10.6009/jjrt.kj00001353146.

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Wu, Qi Zhou, Jing Zhou et Bin Liu. « A Study on the X-Ray Image Quality Evaluation Method Based on Weighted Local Entropy ». Key Engineering Materials 467-469 (février 2011) : 462–68. http://dx.doi.org/10.4028/www.scientific.net/kem.467-469.462.

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In X-ray imaging system, with the change of parameters in material quality, volume, object distance and else of the target objects, manual adjustments of tube voltage and tube current are often needed to get ideal imaging results. Whereas human interventions are often subjective that cannot meet the automation development of X-ray detection system. In view of the above problems, a method for objective quality evaluation in images which is based on weighted local entropy is presented in the paper. Parameters adaptive adjustment in X-ray detection system can be based on this method. The validity of the approach is proved by experiment and comparative analysis with the traditional image quality evaluation function.

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Grabska, Iwona, Ewa Fabiszewska, Katarzyna Pasicz et Witold Skrzyński. « Estimation of the effective focal spot sizes in medical diagnostic X-ray tube assemblies ». Polish Journal of Medical Physics and Engineering 22, n^o 2 (1 juin 2016) : 25–33. http://dx.doi.org/10.1515/pjmpe-2016-0006.

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Abstract For evaluation of the effective focal spot sizes (EFSS), a method suggested by the EN 60336:2005 standard (standard) could be used. In this study we checked whether it is possible to make some deviations from the requirements of the standard without a significant effect on the result. An image receptor with one intensifying screen or two intensifying screens may be used, but the optical value of the slit image shall be in the range of 1.0÷1.4 and the X-ray tube power shall be ranged of about 30%÷50% of the nominal anode input power. A precision scaled magnifier (magnification of 5÷10x and scale of 0.1 mm) may be used for the slit radiogram width measurement instead of a time-consuming scanning of the slit radiogram. These deviations from the requirements of the EN 60336:2005 standard allows to shorten measurement time and to decrease tube current value during X-ray exposures, which reduces the risk of the Xray tube damage.

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Begum, Mahfuza, AS Mollah, MA Zaman, M. Haq et AKM Mizanur Rahman. « A Study on Some Physical Parameters Related to Image Quality and Radiation Safety in Diagnostic Radiology ». Journal of Bangladesh Academy of Sciences 35, n^o 1 (8 juillet 2011) : 7–17. http://dx.doi.org/10.3329/jbas.v35i1.7967.

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Different essential radiographic parameters were studied in order to assess radiographic image quality ensuring reduction of radiation exposure in some diagnostic X-ray facilities of Bangladesh. Different parameters for developing and fixing liquid were investigated in order to eliminate improper film processing techniques. General information about intensifying screen, radiography and mammography film was also collected. X-ray tube voltage, output radiation dose and exposure time for diagnostic X-ray machines were tested to achieve significant dose reduction without loss of diagnostic information. It is found that output radiation dose varies in different diagnostic X-ray installations. 70% X-ray installations achieve the recommended value for tube voltage while 87.5% measure the exposure time appropriately. Radiation dose level at patient waiting room, dark room and around control panel was also measured. About 92.5, 85 and 77.5% installations show their results within the acceptance limit at these positions respectively which provide radiation safety for patients, workers and public in diagnostic radiology.DOI: http://dx.doi.org/10.3329/jbas.v35i1.7967Journal of Bangladesh Academy of Sciences, Vol.35, No.1, 7-17, 2011

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Tavares, Tiago Rodrigues, José Paulo Molin, Lidiane Cristina Nunes, Elton Eduardo Novais Alves, Fábio L. Melquiades, Hudson Wallace Pereira de Carvalho et Abdul Mounem Mouazen. « Effect of X-Ray Tube Configuration on Measurement of Key Soil Fertility Attributes with XRF ». Remote Sensing 12, n^o 6 (17 mars 2020) : 963. http://dx.doi.org/10.3390/rs12060963.

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The successful use of energy-dispersive X-ray fluorescence (ED-XRF) sensors for soil analysis requires the selection of an optimal procedure of data acquisition and a simple modelling approach. This work aimed at assessing the performance of a portable XRF (XRF) sensor set up with two different X-ray tube configurations (combinations of voltage and current) to predict nine key soil fertility attributes: (clay, organic matter (OM), cation exchange capacity (CEC), pH, base saturation (V), and extractable nutrients (P, K, Ca, and Mg). An XRF, operated at a voltage of 15 kV (and current of 23 μA) and 35 kV (and current of 7 μA), was used for analyzing 102 soil samples collected from two agricultural fields in Brazil. Two different XRF data analysis scenarios were used to build the predictive models: (i) 10 emission lines of 15 keV spectra (EL-15), and (ii) 12 emission lines of 35 keV spectra (EL-35). Multiple linear regressions (MLR) were used for model calibration, and the models’ prediction performance was evaluated using different figures of merit. The results show that although X-ray tube configuration affected the intensity of the emission lines of the different elements detected, it did not influence the prediction accuracy of the studied key fertility attributes, suggesting that both X-ray tube configurations tested can be used for future analyses. Satisfactory predictions with residual prediction deviation (RPD) ≥ 1.54 and coefficient of determination (R2) ≥ 0.61 were obtained for eight out of the ten studied soil fertility attributes (clay, OM, CEC, V, and extractable K, Ca, and Mg). In addition, simple MLR models with a limited number of emission lines was effective for practical soil analysis of the key soil fertility attributes (except pH and extractable P) using XRF. The simple and transparent methodology suggested also enables future researches that seek to optimize the XRF scanning time in order to speed up the XRF analysis in soil samples.

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Gonçalves Filho, Luiz C., David S. Monte, Fabio R. Barros et Luiz A. P. Santos. « Radiation dose response of N channel MOSFET submitted to filtered X-ray photon beam ». EPJ Web of Conferences 170 (2018) : 09010. http://dx.doi.org/10.1051/epjconf/201817009010.

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MOSFET can operate as a radiation detector mainly in high-energy photon beams, which are normally used in cancer treatments. In general, such an electronic device can work as a dosimeter from threshold voltage shift measurements. The purpose of this article is to show a new way for measuring the dose-response of MOSFETs when they are under X-ray beams generated from 100kV potential range, which is normally used in diagnostic radiology. Basically, the method consists of measuring the MOSFET drain current as a function of the radiation dose. For this the type of device, it has to be biased with a high value resistor aiming to see a substantial change in the drain current after it has been irradiated with an amount of radiation dose. Two types of N channel device were used in the experiment: a signal transistor and a power transistor. The delivered dose to the device was varied and the electrical curves were plotted. Also, a sensitivity analysis of the power MOSFET response was made, by varying the tube potential of about 20%. The results show that both types of devices have responses very similar, the shift in the electrical curve is proportional to the radiation dose. Unlike the power MOSFET, the signal transistor does not provide a linear function between the dose rate and its drain current. We also have observed that the variation in the tube potential of the X-ray equipment produces a very similar dose-response.

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Ishikawa, Tetsuya. « Accelerator-based X-ray sources : synchrotron radiation, X-ray free electron lasers and beyond ». Philosophical Transactions of the Royal Society A : Mathematical, Physical and Engineering Sciences 377, n^o 2147 (29 avril 2019) : 20180231. http://dx.doi.org/10.1098/rsta.2018.0231.

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The evolution of synchrotron radiation (SR) sources and related sciences is discussed to explain the ‘generation’ of the SR sources. Most of the contemporary SR sources belong to the third generation, where the storage rings are optimized for the use of undulator radiation. The undulator development allowed to reduction of the electron energy of the storage ring necessary for delivering 10 keV X-rays from the initial 6–8 GeV to the current 3 Gev. Now is the transitional period from the double-bend-achromat lattice-based storage ring to the multi-bend-achromat lattice to achieve much smaller electron beam emittance. Free electron lasers are the other important accelerator-based light sources which recently reached hard X-ray regime by using self-amplified spontaneous emission scheme. Future accelerator-based X-ray sources should be continuous wave X-ray free electron lasers and pulsed X-ray free electron lasers. Some pathways to reach the future case are discussed. This article is part of the theme issue ‘Fifty years of synchrotron science: achievements and opportunities’.

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Naji, A. T., M. S. Jaafar, E. A. Ali et S. K. J. Al-Ani. « Effect of Backscattered Radiation on X-Ray Image Contrast ». Applied Physics Research 9, n^o 1 (31 janvier 2017) : 105. http://dx.doi.org/10.5539/apr.v9n1p105.

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This paper assesses the effect of backscattered radiation on X-ray image contrast by evaluating the effect of backscatter reduction on X-ray image contrast. Contrast test tool RMI Densitometer, and different types of fabricated anti backscattered grids have been utilized in this study. The measurements are recorded at different exposure parameters such as X-ray tube peak voltage (kVp), and X-rays intensities (mAs). For each exposure, the contrast of the image is evaluated by measuring the variation in optical densities for aluminium steps wedge. The results showed that the x-ray image contrast can be enhanced by decreasing the amount of backscattered radiation, also the fabricated anti backscattered grids have a remarkable effect in the improvement of X-ray image contrast according to grid’s capability in reducing backscattered radiation. In addition, the effectiveness of fabricated grids in improving image contrast depends on the grid’s material and the geometrical design, as well as the radiation exposure parameters. The image contrast enhancements increased up to 36% with the use of crossed iron steel grid which placed under the film screen combination during exposure.

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Yape, Erlinda O., et Nathaniel M. Anacleto. « Carbothermic Reduction of Misamis Oriental Chromite Ores ». Key Engineering Materials 718 (novembre 2016) : 110–14. http://dx.doi.org/10.4028/www.scientific.net/kem.718.110.

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This study was conducted to determine the non-isothermal and isothermal reduction of chromium ores in the solid-state by reductants like solid carbon under argon and hydrogen-argon atmosphere. Two different chromite ores from local sources , sandy chromite ore from Opol, Misamis Oriental (SCO) and lumpy chromite ore from Manticao, Misamis Oriental (LCM) were used in the study. Isothermal and non-isothermal experiments were conducted in a fixed bed reactor heated in a vertical tube furnace in the temperature range 800 to 1000°C. Raw chromite and reduced samples were subjected to phase analysis and morphology characterization using X-ray flourescence (XRF), X-ray diffraction (XRD), and energy dispersive x-ray spectroscopy (EDX). It was found that reduction does not go to completion at this temperature range. The early stage of reduction of iron was controlled by nucleation and the later by nucleation or chemical reaction or both. The activation energy at the early stage of reduction is estimated to be 44.76 kJ/mol and the later stage of reduction is 144 kJ/mol for SCO and 76.5 kJ/mol for LCM. The reduction of chromium was controlled by chemical reaction.

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Hoehne, Francesca, Maria Ozaeta et Ray Chung. « Routine Chest X-ray after Percutaneous Tracheostomy is Unnecessary ». American Surgeon 71, n^o 1 (janvier 2005) : 51–53. http://dx.doi.org/10.1177/000313480507100109.

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Percutaneous tracheostomy (PT) is an increasingly common procedure in the management of critically ill patients. Current practice for both open and percutaneous tracheostomies is a post-procedure chest X-ray to rule out potentially life-threatening complications such as a pneumothorax or tube malposition. Our study evaluated the utility of chest X-ray after PT. A retrospective chart review was conducted for patients undergoing PT at Kern Medical Center between January 1999 and December 2003. Charts were reviewed for age, sex, and clinical outcome as well as the radiologist's interpretation of the postprocedure chest X-ray. A total of 73 procedures were completed in 47 men and 26 women. The majority of the tracheostomies were in trauma patients who needed prolonged ventilatory support. There were no complications identified on postprocedure chest X-ray. A single patient was converted to an open procedure secondary to bleeding. We conclude that routine chest X-ray after PT is unnecessary.

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