High-energy Images Research Articles

Development of a non-linear dual-energy technique in chest radiography

The dual-energy (DE) technique is useful in chest radiography because it can separate anatomical structures, such as bone and soft tissue. The standard log subtraction, simple smoothing of the high-energy image, anti-correlated noise reduction, and general linear noise reduction algorithms have been used as conventional DE techniques to separate bone and soft tissue. However, conventional DE techniques cannot accurately decompose anatomical structures because these techniques are based on the assumption that X-ray imaging proceeds in a linear relationship. This relationship can cause quantum noise, as well as anatomical loss of normal tissue and difficulty in detecting lesions. In this study, we propose a non-linear DE technique that requires the calculation of the coefficient in advance by using a calibration phantom. The calibration phantom is composed of aluminium and PMMA to calculate non-linear coefficients using the quadratic fitting model for soft tissue and bone. The results demonstrated that the non-linear DE technique exhibited a higher contrast-to-noise ratio, signal-to-noise ratio, and figure of merit at 60/70 kVp and 130 kVp. In addition, it demonstrated better performance and image quality than conventional DE techniques in terms of material decomposition capability. In conclusion, diagnostic accuracy in chest radiography is expected to increase through the non-linear DE technique.

The potential of utilizing mid-energy X-rays for in-line phase sensitive breast cancer imaging

The objective of this study is to demonstrate the potential of utilizing mid-energy x-rays for in-line phase-sensitive breast cancer imaging by phantom studies. The midenergy (50-80kV) in-line phase sensitive imaging prototype was used to acquire images of the contrast-detail mammography (CDMAM) phantom, an ACR accreditation phantom, and an acrylic edge phantom. The low-dose mid-energy phase-sensitive images were acquired at 60 kV with a radiation dose of 0.9 mGy, while the high-energy phase-sensitive images were acquired at 90 kV with a radiation dose of 1.2 mGy. The Phase-Attenuation Duality (PAD) principle for soft tissue was used for the phase retrieval. A blind observer study was conducted and paired-sample T-test were performed to compare the mean differences in the two imaging systems. The correct detection ratio for the CDMAM phantom for phase-contrast images acquired by the low-dose mid-energy system was 56.91%, whereas images acquired by the high-energy system correctly revealed only 40.97% of discs. The correct detection ratios were 57.88% and 43.41% for phase-retrieved images acquired by the low-dose mid-energy and high-energy imaging systems, respectively. The reading scores for all three groups of objects in the ACR phantom were higher for the mid energy imaging system as compared to the high-energy system for both phase-contrast and phase- retrieved images. The calculated edge enhancement index (EEI) from the acrylic edge phantom image for the mid-energy system was higher than that calculated for the high-energy imaging system. The quantitative analyses showed a higher Contrast to Noise Ratio (CNR) as well as a higher Figure of Merit (FOM) in images acquired by the low-dose mid-energy imaging system. The PAD based retrieval method can be applied in mid-energy system without remarkably affecting the image quality, and in fact, it improves the lesion detectability with a patient dose saving of 25%.

Non-Destructive Examination Development for the JHR Material Testing Reactor

The Jules Horowitz Reactor (JHR) is a European material testing reactor (MTR) under construction at the CEA Cadarache centre. It will be dedicated to material and fuel irradiation tests, as well as to the production of medical isotopes. Gamma and X-Ray benches will be implemented in the reactor pool (RER), the irradiated component storage pool (EPI) and in a shielded hot cell for measuring either the whole underwater test device still containing the experimental sample or just the experimental sample before its extraction in the hot cell. The CEA/Cadarache Nuclear Measurement Laboratory (LMN) has been working in collaboration with VTT (Technical Research Centre in Finland Ltd.) since 2008 under a Finnish in-kind contribution agreement. This agreement focuses on the development of NDE systems implementing gamma-ray spectroscopy and high-energy X-ray imaging of the sample and irradiation device with the highest definition possible (resolution of 100 μm). The CEA-VTT technical specifications led to a European call for tenders launched by VTT. The contract was awarded to the Spanish company IDOM for the design, manufacturing, assembly and commissioning of: - Underwater gamma and X-ray (UGXR) mechanical benches and their associated gamma and X-ray collimation systems for the RER and EPI pools - Hot cell gamma and X-ray (HGXR) bench in the JHR NDE hot cell. The Final Design Reviews (FDR) of the UGXR and HGXR systems were completed in 2016. The design phase has been an iterative process in order to manage interfacing specifications and constraints: - Challenging experimental requirements, mainly to cover the wide diversity of sample shapes, sample activity levels and measurement processes, but also to achieve a level of mechanical accuracy to reach the ambitious geometrical resolution target in X-ray imaging, - Environmental constraints (immersion, radiation, compactness, limited accessibility for maintenance), - Nuclear safety constraints (seism, radiation protection). The whole design process has produced a number of elaborate and innovative mechatronic systems, which is rather unusual in nuclear applications since the resulting solutions have benefited from IDOM’s technological expertise in designing and commissioning large telescopes for the astronomy sector. Once the manufacturing phase and assembly finalised, the site acceptance tests for the UGXR and HGXR mechanical systems will be performed in 2019-2020 in the TOTEM facility at the CEA Cadarache center. The underwater benches will be tested in the CESARINE pool to check their requirements.

Assessment of Image Quality of Dual Energy 256 MDCT Technique Focused on keV Changes for MCA Stroke in Cerebral Angiography : Single Energy CT Standard Reference Mode

The purpose of this study was to evaluate the usefulness of cerebral angiography in each energy level by using dual energy technique in CT. Methods were performed on 15 DE images and SE images of CT angiography. For the analysis of images, mean value, standard deviation, SNR and CNR value were determined by setting ROI on MCA, brain parenchyma tissue, and back ground. As a result of concurrent visual evaluation with Likert 5 point scale, the clearest MCA image was confirmed at DE 40 keV and SE 120 kVp(p>0.05). The SNR value of the SE image was measured to be similar to the 40 keV energy level of the DE image. The low energy level image of 40 keV and 50 keV was measured with a high SNR and the contrast ratio was higher than that of the high energy image.

Equivocal and Suspicious Breast Lesions: Can Contrast Enhanced Spectral Mammography Alter their BIRADS Categorization?

Abstract Background: Contrast Enhanced Spectral Mammography (CESM) is an advanced technique to detect the tumor neoan-giogenesis by using the dual energy technique with acquisition of a pair of low and high-energy images only after contrast medium injection. The potential clinical applications are the clarification of mammographically equivocal lesions, the detection of occult lesions on standard mammography, partic-ularly in dense breast, the determination of the extent of disease, the assessment of recurrent disease and the monitoring of the response to chemotherapy. Aim of Study: To assess the potential of Contrast Enhanced Spectral Mammography (CESM) to upstage/downdstage the BIRADS category of equivocal and suspicious breast lesions. Patients and Methods: Thirty female patients with 44 equivocal and suspicious breast lesions, were enrolled in the study, age ranged from 20 to 76 years. All patients underwent conventional mammography and ultrasound then CESM. Results: Mammography + Ultrasound categorized 40/44 lesions (90.9%) lesions to be malignant (BIRADS 4,5) and 4/44 lesions (9.1%) to be benign (BIRADS 1,3). CESM cate-gorized 35/44 lesions (79.5%) to be malignant (BIRADS 4,5) and 9/44 lesions (20.5%) to be benign (BIRADS1,3). Disa-greement about BIRADS category was observed in 25% of the examined lesions including upgraded and downgraded lesions in 11.36% and 13.6% respectively. 100% of up/down graded lesions also proved CESM to be correct in reference to the final diagnosis. Conclusion: CESM has better diagnostic performance than mammography plus Ultrasound and provides a valuable tool to accurately evaluate equivocal and suspicious breast lesions.

85 CyberKnife quality assurance - A manufacturor-independent tools based on a portative high energy imager

85 CyberKnife quality assurance - A manufacturor-independent tools based on a portative high energy imager

Visualization of protein crystals by high-energy phase-contrast X-ray imaging.

For the extraction of the best possible X-ray diffraction data from macromolecular crystals, accurate positioning of the crystals with respect to the X-ray beam is crucial. In addition, information about the shape and internal defects of crystals allows the optimization of data-collection strategies. Here, it is demonstrated that the X-ray beam available on the macromolecular crystallography beamline P14 at the high-brilliance synchrotron-radiation source PETRA III at DESY, Hamburg, Germany can be used for high-energy phase-contrast microtomography of protein crystals mounted in an optically opaque lipidic cubic phase matrix. Three-dimensional tomograms have been obtained at X-ray doses that are substantially smaller and on time scales that are substantially shorter than those used for diffraction-scanning approaches that display protein crystals at micrometre resolution. Adding a compound refractive lens as an objective to the imaging setup, two-dimensional imaging at sub-micrometre resolution has been achieved. All experiments were performed on a standard macromolecular crystallography beamline and are compatible with standard diffraction data-collection workflows and apparatus. Phase-contrast X-ray imaging of macromolecular crystals could find wide application at existing and upcoming low-emittance synchrotron-radiation sources.

Adding the merits of contrast to the ease of mammography; can we highlight what\u2019s behind breast asymmetries?

BackgroundBreast symmetry is one of the major things that radiologists assess when looking at mammograms and is one of the most challenging mammographic findings to evaluate. Contrast-enhanced spectral mammography (CESM) is an emerging mammography technique that has shown comparable sensitivity and specificity to MRI. The purpose of this study is to assess the value of CESM in characterization of breast asymmetries (BAs) and if it should be incorporated in its diagnostic work-up.ResultsThree hundred sixty-five patients with mean age of 47 years were included in the study. CESM was performed aiming for characterization of 380 suspicious or indeterminate breast asymmetries. Assessment of subtracted high-energy images (HEI) markedly improves the overall accuracy reaching 88.4%. Further improvement of the overall accuracy was achieved on combined assessment of the low-energy images (LEI), subtracted high-energy images (HEI), and ultrasound reaching 91.3%.ConclusionCESM is considered as a valuable complementary imaging tool considering the evaluation of breast asymmetries and should be incorporated in its diagnostic work-up in cases not resolved on an initial combined mammography and targeted ultrasound study especially in the presence of a heterogeneous dense breast parenchyma. Yet, this may be hindered in the presence of inflammatory signs because of the overlapping imaging criteria.

Simultaneous vacuum evaporation for CZT thin film fabrication

ABSTRACTTernary semiconductor Cd1-xZnxTe is a solid-state material for high energy radiation detection. This has wide and tunable bandgap (1.45–2.25 eV). It has high resistivity and low noise generation. This can be used for room temperature radiation detection. It has improved charge collection efficiency and very good radiation absorption power for high energy radiations. High energy imaging for diagnostic and surveillance science demands for large area detectors. Large area imaging can only be addressed in thin film form. Thin films of ternary semiconductor can be deposited by various methods like PVD, CVD, MOCVD, Liquid Phase Epitaxy (LPE), Closed Space Sublimation (CSS), Magnetron Sputtering, etc. In this paper, fabrication of thin film of Cd1-xZnxTe by simultaneous vacuum evaporation and fusion of CdTe and ZnTe powders from the same vacuum evaporation unit is presented. Fabricated film is then subjected to structural and optical characterisation studies. CZT thin films have immense applications in imaging areas and such thin films using PVD coating is fabricated in this work with simultaneous fusion of two constituent compounds.

High-Energy X-Ray Compton Scattering Imaging of 18650-Type Lithium-Ion Battery Cell

High-energy synchrotron X-ray Compton scattering imaging was applied to a commercial 18650-type cell, which is a cylindrical lithium-ion battery in wide current use. By measuring the Compton scattering X-ray energy spectrum non-destructively, the lithiation state in both fresh and aged cells was obtained from two different regions of the cell, one near the outer casing and the other near the center of the cell. Our technique has the advantage that it can reveal the lithiation state with a micron-scale spatial resolution even in large cells. The present method enables us to monitor the operation of large-scale cells and can thus accelerate the development of advanced lithium-ion batteries.

Atomic-resolution imaging of carbonyl sulfide by laser-induced electron diffraction.

Measurements on the strong-field ionization of carbonyl sulfide molecules by short, intense, 2 µm wavelength laser pulses are presented from experiments where angle-resolved photoelectron distributions were recorded with a high-energy velocity map imaging spectrometer, designed to reach a maximum kinetic energy of 500 eV. The laser-field-free elastic-scattering cross section of carbonyl sulfide was extracted from the measurements and is found in good agreement with previous experiments, performed using conventional electron diffraction. By comparing our measurements to the results of calculations, based on the quantitative rescattering theory, the bond lengths and molecular geometry were extracted from the experimental differential cross sections to a precision better than ±5 pm and in agreement with the known values.

In-situ characterization and quantification of melt pool variation under constant input energy density in laser powder bed fusion additive manufacturing process

Size and shape of a melt pool play a critical role in determining the microstructure in additively manufactured metals. However, it is very challenging to directly characterize the size and shape of the melt pool beneath the surface of the melt pool during the additive manufacturing process. Here, we report the direct observation and quantification of melt pool variation during the laser powder bed fusion (LPBF) additive manufacturing process under constant input energy density by in-situ high-speed high-energy x-ray imaging. We show that the melt pool can undergo different melting regimes and both the melt pool dimension and melt pool volume can have orders-of-magnitude change under a constant input energy density. Our analysis shows that the significant melt pool variation cannot be solely explained by the energy dissipation rate. We found that energy absorption changes significantly under a constant input energy density, which is another important cause of melt pool variation. Our further analysis reveals that the significant change in energy absorption originates from the separate roles of laser power and scan speed in depression zone development. The results reported here are important for understanding the laser powder bed fusion additive manufacturing process and guiding the development of better metrics for processing parameter design.

Dual-Energy Computed Tomography in Loosening of Revision Hip Prosthesis: A Comparison Between MARS and non-MARS Images

The aim of the study was to assess potential endoprosthesis loosening in patients after revision total hip arthroplasty, based on monochromatic dual-energy computed tomography (DECT) images obtained with and without metal artifact reduction software (MARS) and comparison with the clinical examination and hip function. Twenty-five consecutive patients underwent DECT examinations. Two monochromatic data sets were generated: with MARS (75-keV MARS) and without MARS (140-keV non-MARS) and evaluated for signs of loosening, using a dedicated radiological score. The Harris Hip Score (HHS) was used to evaluate patients' hip function. The mean radiological score for loosening in the non-MARS group was 16.2, in the MARS group 17.0 and was significantly higher (P < 0.001). Radiological loosening evaluation in non-MARS images correlated with the HHS score (ρ = 0.43, P = 0.03), whereas there was no correlation between MARS images and HHS (ρ = 0.15, P = 0.47). New MARS-related artifacts, which hinder implant-bone interface evaluation, were found in 75-keV MARS images ("pseudo-loosening" in 33 of 34 prostheses, "ground-glass blurring" in 20 of 32). High-energy monochromatic DECT images are superior to low-energy DECT MARS images in assessment of the potential loosening and correlate better with the clinical examination outcomes. For revision total hip arthroplasty evaluation, 2 data sets should be assessed inseparably because of extra artifacts in MARS images.

Evaluation of photon-counting spectral mammography for classification of breast microcalcifications

The purpose of this study was to evaluate the feasibility of spectral mammography using a dual-energy method to non-invasively distinguish between type I (calcium oxalate) and type II (calcium hydroxyapatite) microcalcifications. These two types of microcalcifications are difficult to differentiate owing to their similar linear attenuation coefficients. To improve the detection efficiency regarding microcalcifications, a photon-counting detector with energy discrimination capability was used, and the microcalcifications were classified using the optimal dual-energy spectrum. Two energy bins were used to obtain dual-energy images. In this study, a photon-counting spectral mammography system was simulated using Geant4 Application for Tomographic Emission (GATE) simulation tools. A cadmium zinc telluride detector with a high quantum efficiency was used in this study. The effects of classification on the density and thickness of the breast phantom were investigated. Microcalcifications of various sizes, ranging from 130 to 550 μm, were embedded in the phantom. For statistical analysis, the microcalcifications were classified as calcium hydroxyapatite or calcium oxalate based on a score calculation using the dual-energy images. According to the results, the measured contrast-to-noise ratio (CNR) of the calcium hydroxyapatite was higher than that of calcium oxalate in a single-energy image. The calcium hydroxyapatite had a higher attenuation coefficient and slightly higher contrast compared with calcium oxalate. In addition, the microcalcifications were classified into the optimal energy bin in the dual-energy images. This classification showed better performance with a high energy of 50 kVp and an energy threshold of 30 keV. This study demonstrated that using the dual-energy method could improve classification performance because the microcalcifications are affected by the density and thickness of the breast phantom. These results indicate that the classification accuracy was improved when the difference between the low-energy image and high-energy image was used. The dual-energy method can reduce the frequency of the need for biopsies and discriminate between different types of microcalcifications in mammography. These results can improve the efficiency of early breast cancer diagnosis.

A novel dual high-energy X-ray imaging method for materials discrimination

Abstract Dual high energy X-rays have been used for scanning large and dense cargo containers because of their high penetration depth of several meters. Low dependence of attenuation coefficient to the atomic number of materials at high energy X-rays makes the material discrimination so sophisticated in large containers. In this study, a linear function versus the material atomic number is introduced to identify the materials of large container, by involving the response of material attenuation at two energy spectra. Results verify the possibility of separating atomic numbers of materials with a unit resolution using the proposed method.

Prototype system for interventional dual-energy subtraction angiography.

Dual-energy subtraction angiography (DESA) using fast kV switching has received attention for its potential to reduce misregistration artifacts in thoracic and abdominal imaging where patient motion is difficult to control; however, commercial interventional solutions are not currently available. The purpose of this work was to adapt an x-ray angiography system for 2D and 3D DESA. The platform for the dual-energy prototype was a commercially available x-ray angiography system with a flat panel detector and an 80 kW x-ray tube. Fast kV switching was implemented using custom x-ray tube control software that follows a user-defined switching program during a rotational acquisition. Measurements made with a high temporal resolution kV meter were used to calibrate the relationship between the requested and achieved kV and pulse width. To enable practical 2D and 3D imaging experiments, an automatic exposure control algorithm was developed to estimate patient thickness and select a dual-energy switching technique (kV and ms switching) that delivers a user-specified task CNR at the minimum air kerma to the interventional reference point. An XCAT-based simulation study conducted to evaluate low and high energy image registration for the scenario of 30-60 frame/s pulmonary angiography with respiratory motion found normalized RMSE values ranging from 0.16% to 1.06% in tissue-subtracted DESA images, depending on respiratory phase and frame rate. Initial imaging in a porcine model with a 60 kV, 10 ms, 325 mA / 120 kV, 3.2 ms, 325 mA switching technique demonstrated an ability to form tissue-subtracted images from a single contrast-enhanced acquisition.

High-energy industrial 2D X-ray imaging system with effective nonlocal means denoising for nondestructive testing

High-energy industrial X-ray imaging systems are widely used in the field of nondestructive testing for the detection of defects in mechanical material. To improve the defect detection ratio, it is highly important to reduce the amount of noise in this process. The purpose of this study is to develop a nonlocal means denoising algorithm in order to evaluate noise characteristics in a 450 kVp high-energy industrial X-ray imaging system. The analysis approach is tested on two phantom images, and image performance is evaluated by visual assessment, as well as the normalized noise power spectrum, contrast to noise ratio, and coefficient of variation. Improvement in image performance is attributed to the use of NLM denoising algorithm on high-energy industrial X-ray images, and results demonstrate that the proposed algorithm effectively reduces image noise.

A novel simulation and analysis algorithm for high resolution optical transition radiation imaging.

The use of optical transition radiation (OTR) for charged particle beam imaging is a well-established and commonly used technique. As such, simulations of the images expected from an arbitrary transverse beam profile are important in both the design of such OTR imaging systems and the analysis of the data. However OTR image simulations of high-energy, low-emittance particle beams, that are becoming commonplace within accelerator physics, can be extremely challenging to produce and limited in their account of practical factors. In this paper we systematically show how high-energy OTR image simulations can be carried out using low-energy parameters, whilst providing little deviation in the resulting transverse beam profiles. Simulations require significantly less resources and can be combined with further analysis techniques, which would otherwise be too costly to be practically viable. Using this methodology as a basis for OTR simulations, we present a new method of analyzing OTR transverse beam profile data for high-energy, low-emittance beams. In contrast to previous work, this algorithm includes the effects of a finite bandwidth and directly allows the inclusion of optical effects, such as chromatic aberration.

Revealing particle-scale powder spreading dynamics in powder-bed-based additive manufacturing process by high-speed x-ray imaging

Powder spreading is a key step in the powder-bed-based additive manufacturing process, which determines the quality of the powder bed and, consequently, affects the quality of the manufactured part. However, powder spreading behavior under additive manufacturing condition is still not clear, largely because of the lack of particle-scale experimental study. Here, we studied particle-scale powder dynamics during the powder spreading process by using in-situ high-speed high-energy x-ray imaging. Evolution of the repose angle, slope surface speed, slope surface roughness, and the dynamics of powder clusters at the powder front were revealed and quantified. Interactions of the individual metal powders, with boundaries (substrate and container wall), were characterized, and coefficients of friction between the powders and boundaries were calculated. The effects of particle size on powder flow dynamics were revealed. The particle-scale powder spreading dynamics, reported here, are important for a thorough understanding of powder spreading behavior in the powder-bed-based additive manufacturing process, and are critical to the development and validation of models that can more accurately predict powder spreading behavior.

Food commercials do not affect energy intake in a laboratory meal but do alter brain responses to visual food cues in children

Food commercials promote snack intake and alter food decision-making, yet the influence of exposure to food commercials on subsequent neural processing of food cues and intake at a meal is unclear. This study tested whether exposing children to food or toy commercials altered subsequent brain response to high- and low-energy dense food cues and influenced laboratory intake at a multi-item, ad libitum meal. Forty-one 7-9-year-old children (25 healthy weight; 16 with overweight/obesity) completed five visits as part of a within-subjects design where they consumed multi-item test-meals under three conditions: no exposure, food commercial exposure, and toy commercial exposure. On the fourth and fifth visits, functional magnetic resonance imaging (fMRI) was performed while children viewed low- and high-energy dense food images following exposure to either food or toy commercials. Linear mixed models tested for differences in meal energy intake by commercial condition. A whole-brain analysis was conducted to compare differences in response by commercial condition and child weight status. Meal intake did not differ by commercial condition (p = 0.40). Relative to toy commercials, food commercials reduced brain response to high-energy food stimuli in cognitive control regions, including bilateral superior temporal gyri, middle temporal gyrus, and inferior frontal gyrus. Commercial condition * weight status interactions were observed in orbitofrontal cortex, fusiform gyrus, and supramarginal gyrus. Children with overweight/obesity showed increased response in these regions to high-energy stimuli following food commercials. Food commercial exposure affected children's subsequent processing of food cues by reducing engagement of the prefrontal cortex, a region implicated in cognitive control. Even though food commercial exposure did not increase intake at a meal, the effect of reduced prefrontal cortical engagement on a broader range of consumption patterns warrants investigation.