High-resolution x-ray monochromatic imaging for laser plasma diagnostics based on toroidal crystal

Monochromatic x-ray imaging is an essential method for plasma diagnostics related to density information.Large-field high-resolution monochromatic imaging of a He-like iron(Fe XXV)Kαcharacteristic line(6.701 keV)for laser plasma diagnostics was achieved using a developed toroidal crystal x-ray imager.A high-index crystal orientation Ge(531)wafer with a Bragg angle of 75.37°and the toroidal substrate were selected to obtain sufficient diffraction efficiency and compensate for astigmatism under oblique incidence.A precise offline assembly method of the toroidal crystal imager based on energy substitution was proposed,and a spatial resolution of 3-7μm was obtained by toroidal crystal imaging of a 600 line-pairs/inch Au grid within an object field of view larger than 1.0 mm.The toroidal crystal x-ray imager has been successfully tested via side-on backlight imaging experiments of the sinusoidal modulation target and a 1000 line-pairs/inch Au grid with a linewidth of 5μm using an online alignment method based on dual positioning balls to indicate the target and backlighter.This paper describes the optical design,adjustment method,and experimental results of a toroidal crystal system in a laboratory and laser facility.

Soft x-ray Diode-array Diagnostic System for HT-7 Superconducting Tokamak

A diagnostic system of soft x-ray diode-array was set up for HT-7 superconducting tokamak. The system consists of two slot-aperture cameras and is capable of measuring the soft x-ray emission from the plasma on HT-7 device with a high resolution in space and a high response in time. Both cameras, located separately in a horizontal port and a vertical port each with thirty-seven detectors of An-Si surface-barrier diode (SBD) can view the same toroidal cross-section of the plasma from different poloidal chords. In this paper, the structure, principle and performance of the diagnostic system are described and some experimental results observed are presented.

Diagnostic challenges in alcohol use disorder and alcoholic liver disease

Alcohol use disorders represent a heterogeneous spectrum of clinical manifestations that have been defined by the Diagnostic and Statistical Manual of Mental Disorders-5. Excessive alcohol intake can lead to damage of various organs, including the liver. Alcoholic liver disease includes different injuries ranging from steatosis to cirrhosis and implicates a diagnostic assessment of the liver disease and of its possible complications. There is growing interest in the possible different tools for assessing previous alcohol consumption and for establishing the severity of liver injury, especially by noninvasive methods.

Self Consistent Calibration of Detectors and Sources for Hard and Soft X-Ray Diagnostics

X-Ray sources, detectors and optical components are now used in a wide range of applications. What is crucial is the absolute calibration of such devices to permit a quantitative assessment of the system under study. A new X-ray laboratory has been built in Frascati (ENEA) to develop diagnostics for nuclear fusion experiments and study applications of these X-ray techniques in other domains, like new material science, non destructive tests and so on. An in-house developed selfconsistent calibration procedure is described that permits the absolute calibration of sources (X-ray emitted fluxes) and detectors (detection efficiencies) as function of the X-ray photon energy, in the range 2 - 120 keV. The calibration procedure involves the use of an in-house developed code that also predicts the spectral response of any detector in any experimental condition that can be setup in the laboratory. The procedure has been then applied for the calibration and characterisation of gas and solid state imaging detectors, such as Medipix-2, GEM gas detector, CCD camera, Cd-Te C-MOS imager, demonstrating the versatility of the method developed here.

Development of a fast electron bremsstrahlung diagnostic system based on LYSO and silicon photomultipliers during lower hybrid current drive for tokamak

A novel real time fast electron bremsstrahlung (FEB) diagnostic system based on the lutetium yttrium oxyorthosilicate scintillators (LYSO) and silicon photomultipliers (SiPM) has been developed for tokamak.The diagnostic system is dedicated to study the FEB emission in the hard x-ray (HXR) energy range between 10 and 200 keV during the lower hybrid current drive.The system consists of a detection module and three data acquisition and processing (DAP)boards.The detection module consists of annulus LYSO-SiPM detector array and a 12-channel preamplifier module.The DAP boards upload the data to the host computer for displaying and storing through PXI bus.The time and space resolutions of the system are 10 ms and 4 cm,respectively.The experimental results can show the evolution over time and the spatial distribution of FEB.This paper presents the system performance and typical discharge results.

Diagnostic accuracy of thoracic imaging modalities for the detection of COVID-19

The ongoing coronavirus disease 2019(COVID-19)pandemic continues to present diagnostic challenges.The use of thoracic radiography has been studied as a method to improve the diagnostic accuracy of COVID-19.The‘Living’Cochrane Systematic Review on the diagnostic accuracy of imaging tests for COVID-19 is continuously updated as new information becomes available for study.In the most recent version,published in March 2021,a meta-analysis was done to determine the pooled sensitivity and specificity of chest X-ray(CXR)and lung ultrasound(LUS)for the diagnosis of COVID-19.CXR gave a sensitivity of 80.6%(95%CI:69.1-88.6)and a specificity of 71.5%(95%CI:59.8-80.8).LUS gave a sensitivity rate of 86.4%(95%CI:72.7-93.9)and specificity of 54.6%(95%CI:35.3-72.6).These results differed from the findings reported in the recent article in this journal where they cited the previous versions of the study in which a metaanalysis for CXR and LUS could not be performed.Additionally,the article states that COVID-19 could not be distinguished,using chest computed tomography(CT),from other respiratory diseases.However,the latest review version identifies chest CT as having a specificity of 80.0%(95%CI:74.9-84.3),which is much higher than the previous version which indicated a specificity of 61.1%(95%CI:42.3-77.1).Therefore,CXR,chest CT and LUS have the potential to be used in conjunction with other methods in the diagnosis of COVID-19.

The Calibration and Use of a New Ring-Shaped Ionization Chamber for Monitoring and Dosimetry of X-Ray Beams

Today, dosimeters are used generally for dosimetry of the diagnostic X-ray beam. Ionization chambers are appropriate instruments for monitoring and also the dosimetry of X-ray beam in medical diagnostic equipment. The present work introduces design and investigation of a new ring-shaped monitor chamber with a PMMA body, graphite-coated PMMA windows (0.5 mm thick), a special graphite-foil central electrode (0.1 mm thick, 0.7 g/cm3 dense) that creating two sensitive volumes and a central hole for crossing the radiation beam with less attenuation. The results of performance tests conducted at the Nuclear Science and Technology Research Institute, AEOI in Karaj- Iran proved the high short and long-term stability, the very low leakage current, the low directional dependence and very high ion collection efficiency through the special design of the collecting electrode. Moreover, the FLUKA Monte Carlo simulations certified the negligible effect of central electrode on this new ring-shaped monitor chamber. According to the results of the performance tests, the new monitor chamber can be used as a standard dosimeter in order to monitor X-ray beam in primary standard dosimetry laboratories.

Optimized online filter stack spectrometer for ultrashort X-ray pulses

Currently,with the advent of high-repetition-rate laser-plasma experiments,the demand for online diagnosis for the X-ray spectrum is increasing because the laser-plasma-generated X-ray spectrum is very important for characterizing electron dynamics and applications.In this study,scintillators and silicon PIN(P-type–intrinsic-N-type semiconductor)diodes were used to construct a wideband online filter stack spectrometer.The X-ray sensor and filter arrangement was optimized using a genetic algorithm to minimize the condition number of the response matrix.Consequently,the unfolding error was significantly reduced based on numerical experiments.The detector responses were quantitatively calibrated by irradiating the scintillator and PIN diode with various nuclides and comparing the measuredγ-ray peaks.A prototype 15-channel spectrometer was developed by integrating an X-ray detector with front-and back-end electronics.The prototype spectrometer could record X-ray pulse signals at a repetition rate of 1 kHz.Furthermore,an optimized spectrometer was employed to record the real-time spectra of laser-driven bremsstrahlung sources.This optimized spectrometer offers a compact solution for spectrum diagnostics of ultrashort X-ray pulses,exhibiting improved accuracy in terms of spectrum measurements and repetition rates,and could be widely used in next-generation high-repetition-rate high-power laser facilities.

Establishment of Local Diagnostic Reference Levels in Conventional Radiography: A Pilot Study in Dakar, Senegal

Diagnostic Reference Levels (DRLs) are indicators that allow assessing the quality of equipment and procedures from the point of view of the doses delivered to patients and subsequently initiate corrective actions if necessary. The purpose of this study is to encourage health professionals to investigate patient radiation doses and to determine whether those doses comply with the principles of radiation protection in medical fields so as to improve practices by reducing patient exposure without reducing clinical effectiveness. To perform this work, we have investigated patient doses for different radiological examinations from six (6) medical centers in Dakar, including the following nine routine types: chest (PA), abdomen (AP), pelvis (AP), cervical spine (AP), lumbar spine (AP, Lat), hip (AP), thoracic spine (AP, Lat). Three types of data were collected, i.e., X-ray tube machine data, patient data and output measurements. The data were analyzed statistically and the median, minimum, maximum, and third quartile values were calculated and displayed throughout boxplots graphs for all exams and medical centers. The two sigma range (95% confidence interval) was also checked. Comparison of third quartiles of Entrance Surface Dose (ESD) and Dose Area Product (DAP) by type of examination with recommended international DRLs was performed. The third quartile of ESD for pelvis (AP) and thoracic spine (AP) was up to 16% and 38% higher, respectively than their corresponding DRLs in the European Commission Report RP 180 Part 2. For all exams, except thoracic spine (lat), the third quartiles of the dose area product were higher than the corresponding DRLs in the above report. The source of dose variability between medical centers was related to many parameters such as poor radiographic techniques, lack of modern X-ray machines and adequately documented radiation protection practices. The results show the need to develop protocols for dose measurement as well as to carry out quality assurance programs and dose optimization in Senegal.

Land use and landscape pattern change: a linkage to the construction of the Qinghai-Xizang Highway

Based on digital land use data from 1995 to 2000 and road data, the land use and landscape changes of Golmud, Qumaleb and Zhidoi are studied on a macro-scale. Land use and landscape changes in highway buffer zones and city expansion are special subjects. A new formula is used to define the exact degree of dynamic land use. To adequately define land use and landscape pattern changes, the buffer zones, illustrating the changes at different distances from the road, are recognized with ArcGIS 8.1 software. Prominent changes took place in land use and landscape patterns from 1995 to 2000, and the area of built-up land increased by 323.8%. The comprehensive degree of dynamic land use is 2.25, and the degree of dynamic land use of built-up land is the highest, followed by cultivated land. Woodland has the lowest value. The used degree index of land resources declined by 38.8 from 1995 to 2000. Landscape changed dramatically which influenced ecological processes immensely. Different from the corridor effect of other traffic routes, the corridor effect of this section of road is not obvious and its “point” radiation effect can be easily seen. The expanding range of Golmud City is confined to a 3 km buffer, while for Wudaoliang, it is 1 km. No land use change happened in the Nanshankou buffer.

Electrogastrography: Poor correlation with antro-duodenal manometry and doubtful clinical usefulness in adults

AIM: To investigate if there is a correlation between electrical activity measured by electrogastrography (EGG) and contractile activity of the stomach as measured by antroduodenal manometry (ADM). We also studied whether the underlying motility disorder could be predicted from EGG parameters. METHODS: We compared 21 parameters measured from EGG with 8 parameters measured from ADM. The ability of EGG to identify the underlying diagnosis was tested by comparing EGG parameters for each diagnosis group against other patients. The study comprised recordings from 148 patients and 125 females. Their median age was 45 (range 17-76) years. RESULTS: We found few and weak correlations between EGG and ADM. Specifically the correlation between parameters reflecting the response to meal was poor (r = -0.07, P = 0.39). The discriminatory power of EGG for underlying motility disorder was also low. Patients with slow transit constipation (STC) showed a lower postprandial power in normogastric (3.7 ± 0.5 vs 4.0 ± 0.5) and tachygastric (3.5 ± 0.4 vs 3.7 ± 0.4) regions, a lower percentage of time with normogastria [87.2 (56.5-100)% vs 95.7 (0-100)%], and a higher percentage of time with tachygastria [9.3 (0-33)% vs 3.5 (0-100)%] and bradygastria [1.8 (0-20)% vs 0 (0-17.1)%]. Patients with irritable bowel syndrome had a higher percentage of time with normogastria [96.5 (62.5-100)% vs 93.3 (0-100)%] and a less unstable dominant frequency as measured by the instability coefficient [15 (3-77) vs 24 (2-72)]. CONCLUSION: EGG and ADM seem to measure different aspects of gastric motor activity but cannot show a spatial correlation. The diagnostic value of EGG is poor, but EGG may have some value for the identification of patients with STC.

Laser-produced plasma helium-like titanium Kα x-ray source and its application to Rayleigh-Taylor instability study

Several experiments are performed on the ShenGuang-Ⅱ laser facility to investigate an x-ray source and test radiography concepts. X-ray lines emitted from laser-produced plasmas are the most practical means of generating these high intensity sources. By using a time-integrated space-resolved keV spectroscope and pinhole camera, potential helium-like titanium Kα x-ray backlighting （radiography） line source is studied as a function of laser wavelength, ratio of pre-pulse intensity to main pulse intensity, and laser intensity （from 7.25 to ～ 11.3 × 10^15 W/cm2）. One-dimensional radiography using a grid consisting of 5 #m Au wires on 16 μm period and the pinhole-assisted point projection is tested. The measurements show that the size of the helium-like titanium Ka source from a simple foil target is larger than 100 ~m, and relative x-ray line emission conversion efficiency ~x from the incident laser light energy to helium- like titanium K-shell spectrum increases significantly with pre-pulse intensity increasing, increases rapidly with laser wavelength decreasing, and increases moderately with main laser intensity increasing. It is also found that a gold gird foils can reach an imaging resolution better than 5-μm featured with high contrast. It is further demonstrated that the pinhole-assisted point projection at such a level will be a novel two-dimensional imaging diagnostic technique for inertial confinement fusion experiments.

Ab initio Structure Determination of [Co(NH_3)_5Br]Br_2 Using Conventional X-ray Powder Diffraction

The crystal structure of [Co(NH3)5Br]Br2 has been determined ab initio from the conventional X-ray powder diffraction data. The approximate structure with all 7 indeyendent non-H atoms was solved by direct methods. The final orthorhombic unit-cell parameters after Rietveld refinement are: a=13.6927, b=10.7071, c=6.9400A, V=1017.47A3, F30=93(0.0075,43), M20=49, Z=4. Space group is Pnma. The structure agreement factors are: Rp=0.066,Rwp=0.090, RF=0.041, RB=0.042.

Measurement of impurity lines with two-crystal x-ray spectrometers on EAST

To simultaneously measure the He-like and H-like argon spectra, a two-crystal assembly has been deployed to replace the previous single crystal on the tangential x-ray crystal spectrometer.By selecting appropriate crystals with similar Bragg angles, plasma temperature in the range of 0.5 keV≤Te≤10 keV and rotation can be diagnosed based on the He-like and H-like argon spectra. However, due to the added complexity in the two-crystal assembly in which the spectra might be diffracted by two crystals, some additional impurity lines were identified. For example,tungsten（W） lines in different ionization states were diffracted by the He-like and H-like crystal.Additional molybdenum（Mo） lines in the wavelength range of He-like and H-like argon spectra lines were also summarized. The existence of these additional lines caused the fitted temperature to be different from the true values. This paper presents the identified lines through a comparison with available database, which should be included in the fitting procedure.

Reducing Radiation Dose by Using Pulse X-Ray Apparatus

Pulse X-ray diagnostics is capable of reducing the radiation exposure considerably. As for pulse X-ray diagnostic machines, which form pulses with the duration of 0.1 μs, using them one can get outstanding results in this area. This fact can be explained by the long period of luminophor persistence in intensifying X-ray luminescent screens. In this paper we present experimental data, comparing radiation doses, measured at pulse X-ray apparatus and apparatus of constant radiation.

Phase Imaging Using Laser-produced X-ray Sources

A possible novel application of hard x-ray emitted during laser-plasma interaction was discussed. We established an Optical Transform Function to study the joint effect of the spectral distribution and temporal profile of the laser-produced x-ray on x-ray phase imaging. Though the laser-produced x-ray pulse duration is short and incoherent, the analysis confirms that the current x-ray phase imaging theory still holds for laser-produced x-ray phase imaging.

X-ray detection of ingested non-metallic foreign bodies

AIM: To determine the utility of X-ray in identifying non-metallic foreign body(FB) and assess inter-radiologist agreement in identifying non-metal FB. METHODS: Focus groups of nurses, fellows, and attending physicians were conducted to determine commonly ingested objects suitable for inclusion. Twelve potentially ingested objects(clay, plastic bead, crayon, plastic ring, plastic army figure, glass bead, paperclip, drywall anchor, eraser, Lego?, plastic triangle toy, and barrette) were embedded in a gelatin slab placed on top of a water-equivalent phantom to simulate density of a child's abdomen. The items were selected due to wide availability and appropriate size for accidental pediatric ingestion. Plain radiography of the embedded FBs was obtained. Five experienced radiologists blinded to number and types of objects were asked to identify the FBs. The radiologist was first asked to count thenumber of items that were visible then to identify the shape of each item and describe it to a study investigator who recorded all responses. Overall inter-rater reliability was analyzed using percent agreement and κ coefficient. We calculated P value to assess the probability of error involved in accepting the κ value.RESULTS: Fourteen objects were radiographed including 12 original objects and 2 duplicates. The model's validity was supported by clear identification of a radiolucent paperclip as a positive control, and lack of identification of plastic beads(negative control) despite repeated inclusion. Each radiologist identified 7-9 of the 14 objects(mean 8, 67%). Six unique objects(50%) were identified by all radiologists and four unique objects(33%) were not identified by any radiologist(plastic bead, LegoTM, plastic triangle toy, and barrette). Identification of objects that were not present, false-positives, occurred 1-2 times per radiologist(mean 1.4). An additional 17% of unique objects were identified by less than half of the radiologists. Agreement between radiologists was considered almost perfect(kappa 0.86 ± 0.08, P < 0.0001).CONCLUSION: We demonstrate potential non-identification of commonly ingested non-metal FBs in children. A registry for radiographic visibility of ingested objects should be created to improve clinical decision-making.

X-Ray and VUV Spectra from the Laser Plasma Produced with “Kanal-2” Facility

The paper presents experimental results obtained on “Kanal-2” facility. Laser radiation focusing on the surface of plane magnesium targets created the high temperature plasma, which emitted X-ray and vacuum ultraviolet (VUV) radiation. This radiation spectrum was investigated with two spectrographs: the mica crystal spectrograph (working range 8.2 ? - 9.6 ?) and the grazing incidence VUV spectrograph (working rage 30 ? - 130 ?). A set of beryllium stepwise attenuators appended the diagnostic complex and allowed us to get an approximated picture of a continuous spectrum within the range of 2.2 ? - 6.2 ?. The estimation of the plasma electron temperature Te from the ratio between the intensity of the dielectronic satellites and the resonance line gives Te ~ 180 eV. The ratio between the intensity of the resonance and intercombination lines gives the electron density of the emitting zone ne ~ 2 × 1019 cm-3. Some lines observed within the spectral range of 8.5 ? - 9.1 ? belong to none of the transitions of Mg ions. Perhaps the observed spectrum is determined by the transitions in so-called hollow ions of Mg, i.e. in the ions with unfilled inner shells. The spectra obtained with the grazing incidence spectrograph and with the minimum-directioned discrepancy iteration method of spectrum reconstruction from the attenuation curve in the beryllium stepwise attenuators are also presented.

Construction of a predictive model for gastric cancer neuroaggression and clinical validation analysis: A single-center retrospective study

BACKGROUND This study investigated the construction and clinical validation of a predictive model for neuroaggression in patients with gastric cancer.Gastric cancer is one of the most common malignant tumors in the world,and neuroinvasion is the key factor affecting the prognosis of patients.However,there is a lack of systematic analysis on the construction and clinical application of its prediction model.This study adopted a single-center retrospective study method,collected a large amo-unt of clinical data,and applied statistics and machine learning technology to build and verify an effective prediction model for neuroaggression,with a view to providing scientific basis for clinical treatment decisions and improving the tr-eatment effect and survival rate of patients with gastric cancer.AIM To investigate the value of a model based on clinical data,spectral computed to-mography(CT)parameters and image omics characteristics for the preoperative prediction of nerve invasion in patients with gastric cancer.METHODS A retrospective analysis was performed on 80 gastric cancer patients who under-went preoperative energy spectrum CT at our hospital between January 2022 and August 2023,these patients were divided into a positive group and a negative group according to their pathological results.Clinicopathological data were collected,the energy spectrum parameters of primary gastric cancer lesions were measured,and single factor analysis was performed.A total of 214 image omics features were extracted from two-phase mixed energy images,and the features were screened by single factor analysis and a support vector machine.The variables with statist-ically significant differences were included in logistic regression analysis to construct a prediction model,and the performance of the model was evaluated using the subject working characteristic curve.There were statistically significant differences in sex,carbohydrate antigen 199 expression,tumor thickness,Lauren classification and Borrmann classification between the two groups(all P<0.05).Among the energy spectrum parameters,there were statistically significant differences in the single energy values(CT60-CT110 keV)at the arterial stage between the two groups(all P<0.05)and statistically significant differences in CT values,iodide group values,standardized iodide group values and single energy values except CT80 keV at the portal vein stage between the two groups(all P<0.05).The support vector machine model with the largest area under the curve was selected by image omics analysis,and its area under the curve,sensitivity,specificity,accuracy,P value and pa-rameters were 0.843,0.923,0.714,0.925,<0.001,and c:g 2.64:10.56,respectively.Finally,based on the logistic regression algorithm,a clinical model,an energy spectrum CT model,an imaging model,a clinical+energy spe-ctrum model,a clinical+imaging model,an energy spectrum+imaging model,and a clinical+energy spectrum+imaging model were established,among which the clinical+energy spectrum+imaging model had the best efficacy in diagnosing gastric cancer nerve invasion.The area under the curve,optimal threshold,Youden index,sensitivity and specificity were 0.927(95%CI:0.850-1.000),0.879,0.778,0.778,and 1.000,respectively.CONCLUSION The combined model based on clinical features,spectral CT parameters and imaging data has good value for the preoperative prediction of gastric cancer neuroinvasion.