La2Hf2O7:Ti4+ ceramic scintillator for x-ray imaging

2005 ◽  
Vol 20 (3) ◽  
pp. 567-570 ◽  
Author(s):  
Yaming Ji ◽  
Danyu Jiang ◽  
Jianlin Shi
Keyword(s):  
Incident Light ◽  
Synthesis Method ◽  
Light Output ◽  
Optical Transmittance ◽  
Broad Emission Band ◽  
X Rays ◽  
X Ray ◽  
X Ray Imaging ◽  
Charge Transfer Transitions ◽  
Relative Light Output

Transparent ceramic scintillators of La2Hf2O7:Ti4+ were developed by a novel combustion synthesis method. The optical transmittance for a 1.0-mm-thick specimen is about 60% of the incident light, and the x-ray stopping power is also quiet high. The broad emission band centered at 475 nm originates from the oxide-Ti4+ charge-transfer transitions, which renders fast decay time on the order of 10 μs. The highest relative light output has reached about 1.5 times that of Bi4Ge3O12 (BGO) single crystal when excited by 120 kV x-rays.

Defects of Platelet Function Recognized by X-Ray Imaging and Scanning Electron Microscopy

1985 ◽  
Vol 43 ◽  
pp. 610-613
Author(s):  
M.G. Baldini ◽  
S. Morinaga ◽  
D. Minasian ◽  
R. Feder ◽  
D. Sayre ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Cell Biology ◽  
Imaging Technique ◽  
Human Platelets ◽  
X Rays ◽  
X Ray ◽  
X Ray Imaging ◽  
Complex Phenomena ◽  
Scanning Electron

Contact X-ray imaging is presently developing as an important imaging technique in cell biology. Our recent studies on human platelets have demonstrated that the cytoskeleton of these cells contains photondense structures which can preferentially be imaged by soft X-ray imaging. Our present research has dealt with platelet activation, i.e., the complex phenomena which precede platelet appregation and are associated with profound changes in platelet cytoskeleton. Human platelets suspended in plasma were used. Whole cell mounts were fixed and dehydrated, then exposed to a stationary source of soft X-rays as previously described. Developed replicas and respective grids were studied by scanning electron microscopy (SEM).

An investigation into the extent of Lodox imaging usage in South Africa: Radiographer’s perspective

2021 ◽  
Author(s):  
Julius Muchui Thambura ◽  
Jeanette G.E du Plessis ◽  
Cheryl M E McCrindle ◽  
Tanita Cronje
Keyword(s):  
South Africa ◽  
Waiting Times ◽  
Cross Sectional Study ◽  
Trauma Patients ◽  
X Rays ◽  
Online Questionnaire ◽  
Cross Sectional ◽  
Imaging Protocol ◽  
X Ray ◽  
X Ray Imaging

Abstract Introduction Anecdotal evidence suggests that medical professionals in trauma units are requesting additional regional images using conventional x-ray systems, even after trauma patients have undergone full-body Lodox scans. Patients are then exposed to additional radiation, additional waiting times and an increased medical bill. This study aimed at investigating the extent to which Lodox systems were used in trauma units (n=28) in South Africa. Method In this descriptive cross-sectional study, the researcher invited one radiographer from the 28 hospitals in South Africa that use Lodox systems. Radiographers who were most experienced in using the Lodox system completed an online questionnaire. Results Twenty (71.43% n=20) out of twenty-eight radiographers responded. Most hospitals (90%, n=18) were referring patients for additional conventional x-ray images. Radiographers indicated that conventional x-rays were requested for the chest (27.80%, 10/36), the abdomen (16.67%, 6/36), the spine (13.89%, 5/36) and the extremities and skull (19.44%, 7/36). Additionally, radiographers reported using Lodox to perform procedures and examinations usually performed on conventional x-ray systems when conventional x-ray systems were not operational. Conclusion Currently, it is not clear if the use of conventional x-ray imaging following Lodox is necessary, but the results suggest that the practice is commonplace, with healthcare workers in most hospitals (90%, n=18) requesting additional x-ray imaging. The researcher thus recommends that an imaging protocol for Lodox imaging systems should be developed to guide the referral of the patients for further imaging.

scholarly journals Truncated Inception Net: COVID-19 Outbreak Screening using Chest X-rays

2020 ◽  
Author(s):  
Dipayan Das ◽  
KC Santosh ◽  
Umapada Pal
Keyword(s):  
Neural Network ◽  
World Wide ◽  
Imaging Techniques ◽  
Imaging Systems ◽  
Ct Scans ◽  
X Rays ◽  
X Ray ◽  
X Ray Imaging ◽  
Proposed Model ◽  
Different Types

Abstract Since December 2019, the Coronavirus Disease (COVID-19) pandemic has caused world-wide turmoil in less than a couple of months, and the infection, caused by SARS-CoV-2, is spreading at an unprecedented rate. AI-driven tools are used to identify Coronavirus outbreaks as well as forecast their nature of spread, where imaging techniques are widely used, such as CT scans and chest X-rays (CXRs). In this paper, motivated by the fact that X-ray imaging systems are more prevalent and cheaper than CT scan systems, a deep learning-based Convolutional Neural Network (CNN) model, which we call Truncated Inception Net, is proposed to screen COVID-19 positive CXRs from other non-COVID and/or healthy cases. To validate our proposal, six different types of datasets were employed by taking the following CXRs: COVID-19 positive, Pneumonia positive, Tuberculosis positive, and healthy cases into account. The proposed model achieved an accuracy of 99.96% (AUC of 1.0) in classifying COVID- 19 positive cases from combined Pneumonia and healthy cases. Similarly, it achieved an accuracy of 99.92% (AUC of 0.99) in classifying COVID-19 positive cases from combined Pneumonia, Tuberculosis and healthy CXRs. To the best of our knowledge, as of now, the achieved results outperform the existing AI-driven tools for screening COVID-19 using CXRs.

scholarly journals Megavoltage X-Ray Imaging Based on Cerenkov Effect: A New Application of Optical Fibres to Radiation Therapy

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
A. Teymurazyan ◽  
G. Pang
Keyword(s):  
Optical Fibres ◽  
X Rays ◽  
Modulation Transfer ◽  
Imaging Device ◽  
Active Matrix ◽  
X Ray ◽  
X Ray Imaging ◽  
Order Of Magnitude ◽  
Detection Quantum Efficiency ◽  
Cerenkov Effect

A Monte Carlo simulation was used to study imaging and dosimetric characteristics of a novel design of megavoltage (MV) X-ray detectors for radiotherapy applications. The new design uses Cerenkov effect to convert X-ray energy absorbed in optical fibres into light for MV X-ray imaging. The proposed detector consists of a matrix of optical fibres aligned with the incident X rays and coupled to an active matrix flat-panel imager (AMFPI) for image readout. Properties, such as modulation transfer function, detection quantum efficiency (DQE), and energy response of the detector, were investigated. It has been shown that the proposed detector can have a zero-frequency DQE more than an order of magnitude higher than that of current electronic portal imaging device (EPID) systems and yet a spatial resolution comparable to that of video-based EPIDs. The proposed detector is also less sensitive to scattered X rays from patients than current EPIDs.

scholarly journals Optimization of the energy for Breast monochromatic absorption X-ray Computed Tomography

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Pasquale Delogu ◽  
Vittorio Di Trapani ◽  
Luca Brombal ◽  
Giovanni Mettivier ◽  
Angelo Taibi ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Imaging Techniques ◽  
Fixed Dose ◽  
X Rays ◽  
Reconstruction Algorithms ◽  
Contrast Resolution ◽  
X Ray ◽  
X Ray Imaging ◽  
X Ray Computed ◽  
Dose Levels

Abstract The limits of mammography have led to an increasing interest on possible alternatives such as the breast Computed Tomography (bCT). The common goal of all X-ray imaging techniques is to achieve the optimal contrast resolution, measured through the Contrast to Noise Ratio (CNR), while minimizing the radiological risks, quantified by the dose. Both dose and CNR depend on the energy and the intensity of the X-rays employed for the specific imaging technique. Some attempts to determine an optimal energy for bCT have suggested the range 22 keV–34 keV, some others instead suggested the range 50 keV–60 keV depending on the parameters considered in the study. Recent experimental works, based on the use of monochromatic radiation and breast specimens, show that energies around 32 keV give better image quality respect to setups based on higher energies. In this paper we report a systematic study aiming at defining the range of energies that maximizes the CNR at fixed dose in bCT. The study evaluates several compositions and diameters of the breast and includes various reconstruction algorithms as well as different dose levels. The results show that a good compromise between CNR and dose is obtained using energies around 28 keV.

X-Ray Detection of Fissures in Rough Rice Kernels

2017 ◽  
Vol 33 (5) ◽  
pp. 721-728 ◽  
Author(s):  
Zephania R. Odek ◽  
Bhagwati Prakash ◽  
Terry J. Siebenmorgen
Keyword(s):  
Rice Yield ◽  
X Rays ◽  
Milled Rice ◽  
Substantial Impact ◽  
X Ray ◽  
X Ray Imaging ◽  
Head Rice ◽  
Rough Rice ◽  
Head Rice Yield ◽  
Rice Drying

Abstract. X-ray imaging is a viable method of fissure detection in rough rice kernels owing to the ability of X-rays to penetrate hulls, thus allowing visualization of internal rice kernel structure. Traditional methods of fissure detection are only applicable for brown and milled rice, and therefore cannot be used to study fissures developed during rough rice drying. In this study, the fissure detection capability of an X-ray system was evaluated and the relationship between head rice yield (HRY), as measured through laboratory milling, and the percentage of fissured rough rice kernels was determined. Long-grain rice lots of various cultivars were dried using heated air at 60°C, 10% relative humidity (RH) for five drying durations to produce different degrees of fissuring, and then milled to determine HRY. A strong linear correlation (R2 = 0.95) between HRY and the percentage of fissured rough rice kernels after drying was determined. This correlation confirms the substantial impact that kernel fissures have on milling yields. Overall, these findings show the effectiveness of X-ray imaging in rough rice fissure detection, which could allow for drying research that may provide a better understanding of kernel fissuring kinetics. Keywords: Fissures, Grainscope, Head rice yield, Rice drying, X-ray imaging.

scholarly journals Hard X-Ray Imaging Observations by Yohkoh of the 15 November, 1991 Flare

1993 ◽  
Vol 141 ◽  
pp. 258-262
Author(s):  
Taro Sakao
Keyword(s):  
Magnetic Fields ◽  
Energy Release ◽  
Impulsive Phase ◽  
Time Profile ◽  
X Rays ◽  
X Ray ◽  
Precipitation Model ◽  
X Ray Imaging ◽  
Coronal Magnetic Fields ◽  
The Individual

AbstractWe present hard X-ray imaging observations by Yohkoh of the 15 November, 1991 flare. The pre-impulsive and the impulsive phase observations are summarized as follows: (1) Hard X-ray sources in the precursor (or pre–impulsive) phase appear in a much wider area compared with the impulsive phase sources and they show clear evolution just before the onset of the impulsive phase. This suggests that some global re-structuring of coronal magnetic fields led to the impulsive energy release. (2) In the impulsive phase, at the peaks of the individual spikes of the time profile, the bulk of the hard X-ray emission (above 20 keV) originates from the footpoints of the flaring loop. At the valleys between the spikes, X-rays below 30 keV are emitted from near the loop top, while higher energy ones (above 30 keV) are still emitted from the footpoints. Such behavior of hard X-ray sources can be explained by the partial precipitation model.

scholarly journals NuSTAR reveals that the heavily obscured nucleus of NGC 2785 was the contaminant of IRAS 09104+4109 in the BeppoSAX/PDS hard X-rays

2018 ◽  
Vol 619 ◽  
pp. A16
Author(s):  
C. Vignali ◽  
P. Severgnini ◽  
E. Piconcelli ◽  
G. Lanzuisi ◽  
R. Gilli ◽  
...  
Keyword(s):  
X Rays ◽  
X Ray ◽  
Star Forming ◽  
Physical Description ◽  
Enhanced Sensitivity ◽  
X Ray Imaging ◽  
First Time ◽  
In Virtue Of

Context. The search for heavily obscured active galactic nuclei has been revitalized in the last five years by NuSTAR, which has provided a good census and spectral characterization of a population of such objects, mostly at low redshift, thanks to its enhanced sensitivity above 10 keV compared to previous X-ray facilities, and its hard X-ray imaging capabilities. Aims. We aim at demonstrating how NGC 2785, a local (z = 0.009) star-forming galaxy, is responsible, in virtue of its heavily obscured active nucleus, for significant contamination in the non-imaging BeppoSAX/PDS data of the relatively nearby (≈17′) quasar IRAS 09104+4109 (z = 0.44), which was originally mis-classified as Compton thick. Methods. We analyzed ≈71 ks NuSTAR data of NGC 2785 using the MYTorus model and provided a physical description of the X-ray properties of the source for the first time. Results. We found that NGC 2785 hosts a heavily obscured (NH ≈ 3 × 1024 cm−2) nucleus. The intrinsic X-ray luminosity of the source, once corrected for the measured obscuration (L2−10keV ≈ 1042 erg s−1), is consistent within a factor of a few with predictions based on the source mid-infrared flux using widely adopted correlations from the literature. Conclusions. Based on NuSTAR data and previous indications from the Neil Gehrels Swift Observatory (BAT instrument), we confirm that NGC 2785, because of its hard X-ray emission and spectral shape, was responsible for at least one third of the 20–100 keV emission observed using the PDS instrument onboard BeppoSAX, originally completely associated with IRAS 09104+4109. Such emission led to the erroneous classification of this source as a Compton-thick quasar, while it is now recognized as Compton thin.

scholarly journals Measurement of Carbon Ion Photoabsorption Cross Sections Using Laser Plasmas

1990 ◽  
Vol 115 ◽  
pp. 53-56
Author(s):  
B. Wargelin ◽  
S.M. Kahn ◽  
W. Craig ◽  
R. London
Keyword(s):  
Cross Sections ◽  
Grazing Incidence ◽  
X Rays ◽  
Carbon Ion ◽  
X Ray ◽  
Laser Plasmas ◽  
X Ray Imaging ◽  
Low Temperature Plasmas ◽  
Ion Species ◽  
High Column

AbstractLaser plasmas are well-suited to studies of ionic photoabsorption because they can provide highly ionized, low temperature plasmas of high column density, as well as bright, compact continuum X-ray sources which can illuminate the plasma under study. In our experiment, continuum X-rays from a gold laser plasma are partially absorbed as they traverse a carbon plasma and are then dispersed by a grazing incidence reflection grating. An X-ray imaging camera records both the absorbed and unabsorbed spectra simultaneously for later computer analysis to determine the photoabsorption cross sections for each carbon ion species.

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