Dual-energy Technique Research Articles

Dual Energy X-ray Methods for the Characterization, Quantification and Imaging of Calcification Minerals and Masses in Breast

Dual energy (DE) technique has been used by numerous studies in order to detect breast cancer in early stages. Although mammography is the gold standard, the dual energy technique offers the advantage of the suppression of the contrast between adipose and glandular tissues and reveals pathogenesis that is not present in conventional mammography. Both dual energy subtraction and dual energy contrast enhanced techniques were used in order to study the potential of dual energy technique to assist in detection or/and visualization of calcification minerals, masses and lesions obscured by overlapping tissue. This article reviews recent developments in this field, regarding: i) simulation studies carried out for the optimizations of the dual energy technique used in order to characterize and quantify calcification minerals or/and visualize suspected findings, and ii) the subsequent experimental verifications, and finally, the adaptation of the dual energy technique in clinical practice.

Evaluation of soft-plaque stenoses in coronary artery stents using conventional and monoenergetic images: first in-vitro experience and comparison of two different dual-energy techniques.

Non-invasive coronary imaging after stent placement remains challenging. Favorable results for dual-energy computed tomography (DECT) derived monoenergetic (MonoE) images have been reported for this purpose. Nowadays, there are different dual-energy techniques available, each with specific advantages and disadvantages. However, for the evaluation of coronaries after stent implantation there is no systematic comparison between different dual-energy techniques. Therefore, the aim of our study was to compare two widely used DECT systems using an in-stent restenosis (ISR) phantom setup. Soft-plaque-like stenoses (~50% of lumen) were inserted into ten coronary stents embedded in contrast-filled vessel phantoms. A dual-source CT (DSCT) and a dual-layer CT (DLCT) with comparable acquisition and reconstruction parameters were used. Conventional polyenergetic (PolyE) and MonoE images with 9 different levels (40-120 keV) were calculated. ISR assessability was evaluated by subjective scoring using a 5-point scale and by the following quantitative parameters: image noise, visible lumen diameter (VLD) and ISR contrast-to-noise ratio (CNR). A non-significant trend towards larger VLD in DLCT images was observed. Highest noise was found in low-keV MonoE with significantly higher values for DSCT than for DLCT. Conversely, noise was significantly lower for DSCT at higher-keV MonoE. Peak ISR CNR values were found at low-keV MonoE with no significant difference between both systems. However, for PolyE and mid-energy MonoE, CNRs were significantly higher for DSCT. Subjective image quality was significantly better for PolyE and low-keV MonoE than for high-keV MonoE, also without significant difference between both systems. Conspicuity of ISR benefits from DECT. Peak CNRs were comparable for both DECT systems and low-keV MonoE offered the highest CNR values and best subjective image quality. In contrast, high-keV MonoE cannot be recommended for stent evaluation due to poor CNR values and therefore significantly limited visualization of stenoses.

ROLE OF CONTRAST ENHANCED DIGITAL MAMMOGRAPHY IN BREAST LESIONS

Back ground: Breast cancer in women is major public health problem throughout the world, Mammography is basic breast imaging modality for early detection and diagnosis of breast cancer, mammography has its own limitations so contrast enhanced digital mammography is new advanced application using intravenous injection of contrast under development of subtraction and dual energy technique to improve detection of breast cancer. Aim of the Work: To investigate the potential of using intravenous contrast material with full field digital mammography to facilitate the detection and characterization of lesions in the breast. Patients and Methods: This study was conducted on 40 patients with mammographic clinical findings that warranted biopsy recruited from department of Radio-Diagnosis, Ain Shams University hospitals. A technique for demonstrating breast cancers, dualenergy contrast agent–enhanced digital subtraction mammography, was performedfor the 40female patients. The technique consists of high energy and low-energy digital mammography after administration of iodinated contrast agent. Weighted subtraction of the logarithmic transform of these images is then performed to obtain an image that preferentially shows iodine. Results: Of the40 subjects, twenty eight of these tumors enhanced strongly, proved carcinoma, in the other 12 patients, benign tissue enhanced diffusely in two and weakly ocally in two. These results indicate that the technique is feasible and worthy of further study. Conclusion: Contrast-enhanced digital mammography is a new breast imaging technique using full-field digital mammography in conjunction with the injection of an iodinated contrast medium. Dualenergy CEDM also allows shorter acquisition duration and does notrequire prolonged breast compression. This could result in better acceptance from patients and fewer technical problems, such as misregistration of subtracted images.

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.

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.

Synchrotron MicroCT Reveals the Potential of the Dual Contrast Technique for Quantitative Assessment of Human Articular Cartilage Composition.

ABSTRACTDual contrast micro computed tomography (CT) shows potential for detecting articular cartilage degeneration. However, the performance of conventional CT systems is limited by beam hardening, low image resolution (full‐body CT), and long acquisition times (conventional microCT). Therefore, to reveal the full potential of the dual contrast technique for imaging cartilage composition we employ the technique using synchrotron microCT. We hypothesize that the above‐mentioned limitations are overcome with synchrotron microCT utilizing monochromatic X‐ray beam and fast image acquisition. Human osteochondral samples (n = 41, four cadavers) were immersed in a contrast agent solution containing two agents (cationic CA4+ and non‐ionic gadoteridol) and imaged with synchrotron microCT at an early diffusion time point (2 h) and at diffusion equilibrium (72 h) using two monochromatic X‐ray energies (32 and 34 keV). The dual contrast technique enabled simultaneous determination of CA4+ (i.e., proteoglycan content) and gadoteridol (i.e., water content) partitions within cartilage. Cartilage proteoglycan content and biomechanical properties correlated significantly (0.327 < r < 0.736, p < 0.05) with CA4+ partition in superficial and middle zones at both diffusion time points. Normalization of the CA4+ partition with gadoteridol partition within the cartilage significantly (p < 0.05) improved the detection sensitivity for human osteoarthritic cartilage proteoglycan content, biomechanical properties, and overall condition (Mankin, Osteoarthritis Research Society International, and International Cartilage Repair Society grading systems). The dual energy technique combined with the dual contrast agent enables assessment of human articular cartilage proteoglycan content and biomechanical properties based on CA4+ partition determined using synchrotron microCT. Additionally, the dual contrast technique is not limited by the beam hardening artifact of conventional CT systems. © 2019 The Authors. Journal of Orthopaedic Research® published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 38:563–573, 2020

Quantitative assessment of three vendor’s metal artifact reduction techniques for CT imaging using a customized phantom

A metal implant was placed in an acrylic phantom to enable quantitative analysis of the metal artifact reduction techniques used in computed tomography (CT) scanners from three manufacturers. Two titanium rods were placed in a groove in a cylindrical phantom made by acrylic, after which the groove was filled with water. The phantom was scanned using three CT scanners (Toshiba, GE, Siemens) under the abdomen CT setting. CT number accuracy, contrast-to-noise ratio, area of the metal rods in the images, and fraction of affected pixel area of water were measured using ImageJ. Different iterative reconstruction, dual energy, and metal artifact reduction techniques were compared within three vendors. The highest contrast-to-noise ratio of three scanners were 85.7 ± 8.4 (Toshiba), 85.9 ± 11.7 (GE), and 55.0 ± 14.8 (Siemens); and the most correct results of metal area were 157.1 ± 1.4 mm2 (Toshiba), 155.0 ± 1.0 (GE), and 170.6 ± 5.3 (Siemens). The fraction of affected pixel area obtained using single-energy metal artifact reduction of Toshiba scanner was 2.2% ± 0.7%, which is more favorable than 4.1% ± 0.7% obtained using metal artifact reduction software of GE scanner (p = 0.002). Among all quantitative results, the estimations with fraction of affected pixel areas matched the effect of metal artifact reduction in the actual images. Therefore, the single-energy metal artifact reduction technique of Toshiba scanner had a desirable effect. The metal artifact reduction software of GE scanner effectively reduced the effect of metal artifacts; however, it underestimated the size of the metal rods. The monoenergetic and dual energy composition techniques of Siemens scanner could not effectively reduce metal artifacts.

Feasibility and utility of dual-energy chest CTA for preoperative planning in pediatric pulmonary artery reconstruction.

The purpose of this study was to assess in pediatric pulmonary artery (PA) reconstruction candidates the feasibility and added utility of preoperative chest computed tomography angiography (CTA) using dual-energy technique, from which perfused blood volume (PBV)/iodine maps can be generated as a surrogate of pulmonary perfusion. Pediatric PA reconstruction patients were prospectively recruited for a new dose-neutral dual-energy CTA protocol. For each case, the severity of anatomic PA obstruction was graded by two pediatric cardiovascular radiologists in consensus using a modified Qanadli index. PBV maps were qualitatively reviewed and auto-segmented using Siemens syngo.via software. Associations between Qanadli scores and PBV were assessed with Spearman correlation (r) and ROC analysis. Effective radiation doses were estimated from dose-length product and ICRP 103k-factors, using cubic Hermite spline interpolation. 19 patients were recruited with mean (SD) age of 6.0 (5.1), 11 (57.9%) female, 11 (73.7%) anesthetized. Higher QS correlated with lower PBV, both on a whole lung (r = - 0.54, p < 0.001) and lobar (r = - 0.50, p < 0.001) basis. The lung with lowest absolute PBV was predictive of the lung with highest Qanadli score, with AUC of 0.70 (95% CI 0.47-0.93). Qualitatively, PBV maps were heterogeneous, corresponding to multifocal PA stenoses, with decreased iodine content in areas of most severe obstruction. In conclusion, dual-energy chest CTA is feasible for pediatric PA reconstruction candidates. PBV maps show deficits in regions of more severe anatomic obstruction and may serve as a novel biomarker in this population.

Proposing an intelligent approach for measuring the thickness of metal sheets independent of alloy type

Radiation based gauges have been widely utilized as a nondestructive and robust tool for measuring the thickness of metal sheets in industry. The typical radiation thickness meter can just work accurately when the composition of the material is fixed during the measurement process. In conditions that material composition may differ substantially from the nominal composition, such as manufacturing rolled metals factories, the thickness measurements would be along with errors. The purpose of the present research is resolving the problem of measuring the thickness of metal sheets with various alloys. The aluminum is investigated in this work as a case study but the procedure can be applied for other types of metals. As the first step, the performance of various arrangements of two main detection techniques, named dual energy and dual modality, were investigated using MCNPX code to obtain optimum technique and arrangement. The simulation results indicated that a binary combination of 241Am-60Co isotopes as the source and one transmission detector in dual energy technique is the most appropriate choice. After then, an experimental setup based on the obtained optimal technique from simulation investigations was established. The aluminum sheets with 4 alloy types of 1050, 3105, 5052 and 6061 and thicknesses in the range of 0.2–4 cm with a step of 0.2 cm were tested and the obtained data were implemented for testing and training the artificial neural network (ANN). The proposed methodology could predict the thickness of aluminum sheet independent of its alloy type with an error of less than 0.04 cm in experiments.

Abstract P5-01-02: Glandular dose in contrast-enhanced dual-energy mammography

Abstract INTRODUCTION Estimation of the Average Glandular Dose (AGD) absorbed by the breast during x-ray based examination is an established part of quality control procedures for breast imaging, both for standard mammography and new techniques as digital breast tomosynthesis (DBT) and contrast enhanced digital mammography (CEDM). It is however fundamental that every optimization program obtains an adequate imaging quality. In our study we evaluated the AGD absorbed by the breast, during CEDM examinations, performed with Dual Energy (DE) technique in our Department. MATERIALS AND METHODS We retrospectively evaluated 37 DE mammograms; we reported and analyzed AGD, Entrance Skin Exposure (ESE), anode/filter combinations, breast thickness, kV (kilovolt), mAs (milliAmpere per second), and compression in daN (decaNewton) values, for each mammography view obtained on high and low energy. In 10 Patients, it was possible to compare DE with a recent standard mammography performed on the same mammography unit. RESULTS AGD values for the entire DE study, in craniocaudal and mediolateral oblique views, resulted between 4.23 mGy and 13.44 mGy; based on the breast thickness (27-79 mm) and on the anod/filter combination. We found out a significantly lower AGD for small breast thicknesses and Mo/Rh and Mo/Cu combination compared to Rh/Rh and Rh/Cu. In the whole study evaluation, the AGD percentage report due to low and high energy acquisitions resulted between 76.8% and 81.6%, and between 18.4% and 23.2%, respectively. For the 10 Patients in which was possible a direct comparison with the data obtained with recent standard mammography, resulted a ratio between DE AGD and standard mammography AGD variable from 1.43 to 2.48 (mean value: 2.0), again with lower AGD values obtained with Mo/Rh - Mo/Cu combination and for small breast thicknesses. AGD ratio between low energy and standard mammography acquisition resulted between 1.23 and 3.31. DISCUSSION CEDM is proving to have all the potential to get a definite role in diagnosis and breast tumor staging, providing a direct correlation between morphologic and functional imaging. In our study we assessed the dosimetry to determine if an additional x-ray exposure will be a limit to DE use and, if that is the case, in which measure. Data in the literature on DE dosimetry are still spare and extremely heterogenous. In any case, the increase of delivered dose could be justifiable when compared to the great benefits given by this technique in breast cancer early diagnosis and staging, especially in dense breast tissue, in the follow-up of Patients with breast cancer history and in case of MRI incompatibility. Furthermore, when compared to MRI, CEDM is an easy-access, low-cost, fast and well accepted exam by the patient. CONCLUSIONS Although the risk of induced carcinogenesis associated with x-ray breast modalities is small, dosimetric aspects should be considered both for the risk evaluation and for optimization of acquisition systems; with the advance of the technologies we will be able to have a dose reduction by maintaining high quality standards. Results obtained from this preliminary study needs to be extended by a larger case study to get a complete evaluation and comprehension of the phenomenon. Citation Format: Cossu E, Castellani F, Fiaschetti V, Mariateresa M, Tiziana R, Angelo T. Glandular dose in contrast-enhanced dual-energy mammography [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-01-02.

An investigation of radiation damage in rat lungs following dual-energy micro-CT imaging

Dual-energy micro-CT imaging techniques have been developed to enable accurate identification and segmentation of different tissues. Using dual-energy techniques for thoracic imaging requires obtaining images at multiple respiratory or cardiac phases, and may require images obtained pre- and post-contrast enhancement for each energy. In this study, we investigated if the multiple images obtained during dual-energy imaging resulted in an x-ray dose sufficiently high to interfere with or mask symptoms of respiratory disease. We performed a dual-energy micro-CT study (5 images in a single session, with a cumulative entrance dose of 0.47 Gy) to image the thorax of healthy male Brown Norway rats at 8 weeks of age. Groups of 5 rats were euthanized at 1 day, 1, 2, 3, and 4-weeks post-exposure and the lungs were excised and examined by histology (H&E stained slides). Positive controls were exposed to an entrance dose of 1.5 Gy and euthanized at 2 weeks and negative controls were not exposed to x-rays. There was no evidence of alveolar damage or inflammation for any of the animals exposed to the dual-energy imaging session compared with the negative control group. Inflammation was evident for the positive controls. This study concludes that the dual-energy imaging protocol developed in this study does not contribute to lung tissue damage. For preclinical respiratory research, these results show that any inflammation and alveolar damage observed in the lungs would be attributed to the disease model under investigation, and not be affected by obtaining 3D dual-energy micro-CT images.

Interscanner and Intrascanner Comparison of Virtual Unenhanced Attenuation Values Derived From Twin Beam Dual-Energy and Dual-Source, Dual-Energy Computed Tomography

The aim of the current study was to evaluate the reliability and comparability of virtual unenhanced (VUE) attenuation values derived from scans of a single-source, dual-energy computed tomography using a split-filter (tbDECT) to a dual-source dual-energy CT (dsDECT). In this retrospective study, comparisons for tbDECT and dsDECT were made within and between different dual-energy platforms. For the interscanner comparison, 126 patients were scanned with both scanners within a time interval of 224 ± 180 days; for the intrascanner comparison, another 90 patients were scanned twice with the same scanner within a time interval of 136 ± 140 days. Virtual unenhanced images were processed off of venous phase series. Attenuation values of 7 different tissues were recorded. Disagreement for VUE HU measurements greater than 10 HU between 2 scans was defined as inadequate. The interscanner analysis showed significant difference between tbDE and dsDE VUE CT values (P < 0.01) for 6 of 7 organs. Percentage of cases that had more than 10 HU difference between tbDE and dsDE for an individual patient ranged between 15% (left kidney) and 62% (spleen).The intrascanner analysis showed no significant difference between repeat scans for both tbDECT and dsDECT (P > 0.05). However, intrascanner disagreements for the VUE HU measurements greater than 10 HU were recorded in 10% of patients scanned on the tbDECT and 0% of patients scanned on the dsDECT. The organs with the highest portion of greater than 10 HU errors were the liver and the aorta (both 20%). Dual-energy techniques vary in reproducibility of VUE attenuation values. In the current study, tbDECT demonstrated higher variation in VUE HU measurements in comparison to a dsDECT. Virtual unenhanced HU measurements cannot be reliably compared on follow-up CT, if these 2 different dual-energy CT platforms are used.

71. Contrast-enhanced spectral mammography. Analysis of region of interest based on gray levels: a preliminary multi-center study in Puglia (Italy)

Purpose Contrast-Enhanced Spectral Mammography (CESM) allows the acquisition of low- and high-energy digital mammograms with Dual-Energy technique after a single injection of iodinated contrast medium (CM) obtaining the production of recombined mammographic images [1] , [2] . The aim of this paper is to characterize ROI and measure the gray-level parenchymal background in order to improve the lesion detection in CESM. Methods We have selected 42 patients positive to the methodic for the presence of at least one findings after histological examination.We have evaluated 65 lesions (52 malignant and 13 benign) from 0.5 to 13.5 cm. Primary and secondary (if present) lesions have been identified and their diameters have been measured in axial projection. Regions including the parenchymal background and the non-contrasted background were also marked in both low-energy and recombined images.For each region the statistical parameters of gray levels were recorded by CESM instrumentation and have been elaborated by multivariate statistics and machine learning techniques in order to characterize each region and define a background intensity indicator, not yet defined objectively. Results The analysis on our available dataset seems to underline significant differences between ROIs with lesions and regions marked on the parenchymal background with respect to the coefficient of variation, i.e. standard deviation of the gray levels of the marked area compared to the mean value of the same) in recombined images.We have found an increase of the coefficient of ROIs greater than 20% with respect to the coefficient of the regions marked on parenchymal background in 57 lesions. Conclusions As preliminary results, an indicator to detect the parenchymal background can be identified as the coefficient of variation. Data collection is currently ongoing because a more massive data sample will be useful to increase the sensitivity in the lesion detection by CESM device, even in patients with a medium-high value of background.

Histogram-based comparison between dynamic and static lung perfused blood volume images using dual energy CT

ObjectiveThe purpose of this study was to compare the results of a histogram-based analysis of static and dynamic lung perfused blood volume (LPBV) images. MethodsSixty-five patients (mean age: 61.3 years, 36 male) underwent dynamic and static LPBV for evaluation of pulmonary vascular diseases (n = 11), lung carcinoma (n = 27) or pulmonary thromboembolism (PTE: n = 27). Seven sets of dynamic sequential scans were performed at the pulmonary trunk using dual-energy technique before the static LPBV scan. The image of lung parenchyma that showed the greatest mean attenuation in dynamic series was defined as the peak dynamic LPBV image. The differences and correlations in the mean attenuation, image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), histogram skewness and histogram kurtosis were evaluated according to the type of disease in static and dynamic LPBV images. ResultsStatic LPBV images showed significantly larger mean attenuation (Rt:24.2, Lt: 24.2), SNR (Rt:2.31, Lt:2.30), and CNR (Rt:2.40, Lt:2.39), and smaller kurtosis values (Rt:1.06, Lt:0.61) values in comparison to dynamic LPBV images (p < 0.001); however, with the exception of kurtosis of the left lung (r = 0.17), these values were well-corrected with that of the dynamic LPBV images in these values (r = 0.4–0.77, p ≤ 0.001) without kurtosis of left lung (r = 0.17) in all patients. The histogram kurtosis of static LPBV image showed a good correlation with that of dynamic LPBV (r = 0.41–0.77, p < 0.05), especially in patients with PTE. ConclusionIn patients with PTE, the static LPBV image valueswere well correlated with the peak dynamic LPBV images which demonstrated pulmonary artery-dominant flow.

Optimisation of DECT Spectral Separation for Quantitative Evaluation of Clinical Contrast Agent

This study is focusing on the evaluation and optimization of the spectral separation of clinical contrast agents in DECT imaging. Based on previous literatures, the two most important methods to evaluate the DECT systems are the evaluation of the DE ratio and the contrast to noise ratio. In the first study, abdomen CT phantom was used with an insertion of three contrast media: iodine, gadolinium and milk. The phantom was scanned using abdomen routine protocols for both single and dual energy CT. The scanner was then switched from DECT to SECT to scan the phantom with single energy ranges such as 80 kV, 100 kV, 120 kV and 140 kV. The MATLAB was used to fuse the images by weighted averaging 30 % low energy and 70 % high energy. The collected data were analysed using the Weasis software. Statistical analyses were then performed to compare the contrast to noise ratio with different tube voltage combinations. The MATLAB was again used to fuse the images. The results showed that 80/140 kV is the best spectral separation for evaluation of the clinical contrast medium. In addition, the results displayed significant CNR effect (p < 0.05) for all DECT images. The dual energy technique improved the contrast to noise ratio and dual energy ratio for the DECT images.

Theoretical study of a simplified implementation model of a dual-energy technique for computed tomography

The article describes a theoretical study of the simplified implementation of dual energy technique (DET) for computed tomography (CT). The implementation is based on the X-ray pre-filter. Two sets of projections, acquired for two maximal X-ray energies, are transformed to the projections of DET parameters. The density and effective atomic number of the test object fragments are estimated after a separate recovery of the internal structure of the test object for each of the DET parameters. The choice of pre-filter thickness is discussed. An example of the initial projections simulation and the estimation of the internal structure of cylindrical objects are shown.

Comparison study of noise reduction algorithms in dual energy chest digital tomosynthesis

Dual energy chest digital tomosynthesis (CDT) is a recently developed medical technique that takes advantage of both tomosynthesis and dual energy X-ray images. However, quantum noise, which occurs in dual energy X-ray images, strongly interferes with diagnosis in various clinical situations. Therefore, noise reduction is necessary in dual energy CDT. In this study, noise-compensating algorithms, including a simple smoothing of high-energy images (SSH) and anti-correlated noise reduction (ACNR), were evaluated in a CDT system. We used a newly developed prototype CDT system and anthropomorphic chest phantom for experimental studies. The resulting images demonstrated that dual energy CDT can selectively image anatomical structures, such as bone and soft tissue. Among the resulting images, those acquired with ACNR showed the best image quality. Both coefficient of variation and contrast to noise ratio (CNR) were the highest in ACNR among the three different dual energy techniques, and the CNR of bone was significantly improved compared to the reconstructed images acquired at a single energy. This study demonstrated the clinical value of dual energy CDT and quantitatively showed that ACNR is the most suitable among the three developed dual energy techniques, including standard log subtraction, SSH, and ACNR.

Inline multi-material identification via dual energy radiographic measurements

In the waste recycling industry, material separation is of key importance. In this paper, we present a new material identification method, based on dual-energy X-ray radiographic images, developed in the context of waste recycling industry. The algorithm is based on a dual energy technique and allows to estimate the effective atomic number of the sample under investigation. A projection simulator with high accuracy that allows to simulate realistic measurements of a wide range of materials is used. The resulting virtual measurements are then used in an identification tool, which achieves the identification by comparing the virtual and actual measurements. Via this procedure, an extensive range of materials and thicknesses can be analyzed and identified. Finally, an optimization scheme has been developed, which allows the selection of an ideal setting for the scanner, in order to optimize the identification process.

Application of Dual-Energy CT Non-Linear Fusion Technology in Improving CTA Image Quality of Renal Cancer

Objective: To explore the significance of dual-energy CT non-linear fusion technique in improving the quality of CTA image of renal cancer. Methods: The CTA images of 100 patients who had been confirmed by pathology as renal cancer were collected and were randomly divided into experimental group and control group with 50 cases respectively. The two groups of patients were treated with iodine concentration of 300 mg/ml and 350 mg/ml non-ionic contrast agent, with a dosage of 1.5 ml/kg and an injection rate of 4 ml/s. The contrast agent intelligently tracking method was adopted bolus. The control group used the conventional CTA scanning, with a reference tube voltage/tube current of 100 kv/ref150 mas. The experimental group adopted the double energy scanning, with ball tube A and ball tube B. The reference tube voltage/tube current was 100 kv/ref250 mas and sn150 kv/ref125 mas respectively. The images of the experimental group were non-linear fused to obtain the Mono+ 55 kev single-energy images. The CT value, SNR contrast ratio of the abdominal aorta, renal artery and tumor tissue of the experimental group images and the 100 KV images and the Mono+ 55 kev images of the control group were compared. The objective evaluation and subjective evaluation of the image quality of the three groups of images was performed. Results: The results showed that the 100 kV images of the experimental group were statistically different from those of the control group (P05) in CT value, SNR and CNR (P 0.05). The subjective evaluation of image quality showed that there was no significant difference between Mono+ 55 kev images and control group images, and the quality of Mono+ 55 kev images was higher than that of experimental group 100 kV images. Conclusion: The dual-energy CT non-linear fusion technique can improve the quality of CTA image in patients with renal cancer, and it is possible to obtain high quality CTA images with low iodine concentration contrast agent.