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- 摘要
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- 实验方案
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[IEEE 2019 International Topical Meeting on Microwave Photonics (MWP) - Ottawa, ON, Canada (2019.10.7-2019.10.10)] 2019 International Topical Meeting on Microwave Photonics (MWP) - On-chip Photonic Method for Doppler Frequency Shift Measurement
摘要： 4-D-computed tomography (4DCT) provides not only a new dimension of patient-specific information for radiation therapy planning and treatment, but also a challenging scale of data volume to process and analyze. Manual analysis using existing 3-D tools is unable to keep up with vastly increased 4-D data volume, automated processing and analysis are thus needed to process 4DCT data effectively and efficiently. In this paper, we applied ideas and algorithms from image/signal processing, computer vision, and machine learning to 4DCT lung data so that lungs can be reliably segmented in a fully automated manner, lung features can be visualized and measured on the fly via user interactions, and data quality classifications can be computed in a robust manner. Comparisons of our results with an established treatment planning system and calculation by experts demonstrated negligible discrepancies (within ±2%) for volume assessment but one to two orders of magnitude performance enhancement. An empirical Fourier-analysis-based quality measure-delivered performances closely emulating human experts. Three machine learners are inspected to justify the viability of machine learning techniques used to robustly identify data quality of 4DCT images in the scalable manner. The resultant system provides a toolkit that speeds up 4-D tasks in the clinic and facilitates clinical research to improve current clinical practice.
关键词： Biomedical image processing,machine learning algorithms,classification algorithms,data visualization,computed tomography,morphological operations,image analysis
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE PES Asia-Pacific Power and Energy Engineering Conference (APPEEC) - Macao, Macao (2019.12.1-2019.12.4)] 2019 IEEE PES Asia-Pacific Power and Energy Engineering Conference (APPEEC) - A Single-Stage Flyback LED Driver Based On Energy Distribution Without Electrolytic Capacitor
摘要： The lp (0 < p < 1) regularization has attracted a great attention in the compressive sensing field, because it can obtain sparser solutions than the well-known l1 regularization. Recently, we developed an approximate general analytic thresholding representation for any lp regularization with 0 < p < 1. The derived thresholding representations are exact for the well-known soft-threshold filtering for l1 regularization and the hard-threshold filtering for l0 regularization. Because the lp regularization is a nonconvex problem, an iterative algorithm can only converge to local optima instead of the global optimum. In this paper, we propose an alternating iteration algorithm for computed tomography reconstruction in a thresholding form based on our general analytic thresholding representation for better convergent properties. The alternating iteration algorithm alternatively minimizes one l1 and one lp (0 < p < 1) regularized objective functions. While the lp regularization can help to find a sparser solution, the l1 regularization can help to monitor the solution not away from the global optimum. Both numerical simulations and phantom experiments are performed to evaluate the proposed alternating iteration algorithm. Compared with the lp (0 < p < 1) regularization using a single p, the proposed alternating iteration algorithm reduces more data measurements for accurate reconstruction and is more robust for projection noise.
关键词： image reconstruction,Compressive sensing,least square solution,computed tomography,alternating iteration,lp regularization
更新于2025-09-23 15:19:57
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Modular Synthesis of Waveguide Bandpass Filters Using Dual-Mode Resonators
摘要： We present a new decomposition approach for dual-energy computed tomography (DECT) called SIRZ that provides precise and accurate material description, independent of the scanner, over diagnostic energy ranges (30 to 200 keV). System independence is achieved by explicitly including a scanner-specific spectral description in the decomposition method, and a new X-ray-relevant feature space. The feature space consists of electron density, and a new effective atomic number, which is based on published X-ray cross sections. Reference materials are used in conjunction with the system spectral response so that additional beam-hardening correction is not necessary. The technique is tested against other methods on DECT data of known specimens scanned by diverse spectra and systems. Uncertainties in accuracy and precision are less than 3% and 2% respectively for the results compared to prior methods that are inaccurate and imprecise (over 9%).
关键词： system-independent CT,Beam-hardening correction,electron density,effective atomic number,quantitative x-ray characterization,dual-energy computed tomography,photoelectric-compton decomposition
更新于2025-09-23 15:19:57
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Accuracy and reliability of measurements performed using two different software programs on digital models generated using laser and computed tomography plaster model scanners
摘要： Objective: The aim of this study was to compare the accuracy and reliability of measurements performed using two different software programs on digital models generated using two types of plaster model scanners (a laser scanner and a computed tomography [CT] scanner). Methods: Thirty plaster models were scanned with a 3Shape laser scanner and with a Flash CT scanner. Two examiners performed measurements on plaster models by using digital calipers and on digital models by using Ortho Analyzer (3Shape) and Digimodel? (OrthoProof) software programs. Forty-two measurements, including tooth diameter, crown height, overjet, overbite, intercanine and intermolar distances, and sagittal relationship, were obtained. Results: Statistically significant differences were not found between the plaster and digital model measurements (ANOVA); however, some discrepancies were clinically relevant. Plaster and digital model measurements made using the two scanning methods showed high intraclass coefficient correlation values and acceptable 95% limits of agreement in the Bland-Altman analysis. The software used did not influence the accuracy of measurements. Conclusions: Digital models generated from plaster casts by using laser and CT scanning and measured using two different software programs are accurate, and the measurements are reliable. Therefore, both fabrication methods and software could be used interchangeably.
关键词： Computed tomography,Three-dimensional diagnosis and treatment planning,Digital models,Three-dimensional scanner
更新于2025-09-23 15:19:57
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Pulverized coal combustion application of laser-based temperature sensing system using computed tomography a?? Tunable diode laser absorption spectroscopy (CT-TDLAS)
摘要： The investigation of combustion phenomena in pulverized coal flames is significant for combustion optimization related to energy conservation and emission reduction. Real-time two dimensional (2D) temperature and concentration distributions play an important role for combustion analysis. The non-contact and fast response 2D temperature and concentration distribution measurement method was developed in this study. The method is based on a combination of computed tomography (CT) and tunable diode laser absorption spectroscopy (TDLAS). The accuracy evaluation of developed 32-path CT-TDLAS demonstrated its feasibility of 2D temperature measurement. 32-path CT-TDLAS was applied to CH4 and 5 kg/h coal combustion fields for 2D temperature measurement. The time-series 2D temperature distribution in coal combustion furnace was measured using 32-path CT-TDLAS measurement cell with kHz time resolution. The transient temperature field of combustion flame directly reflects the combustion mode and combustion stability. The measurement results demonstrate its applicability of CT-TDLAS to various types of combustor, especially the combustion fields with coal and ash particles. CT-TDLAS method with kHz response time enables the real-time 2D temperature measurement to be applicable for combustion analysis.
关键词： 2D temperature measurement,Computed tomography (CT),Tunable diode laser absorption spectroscopy (TDLAS),Time-series distribution,Coal combustion
更新于2025-09-23 15:19:57
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Prior-Guided Metal Artifact Reduction for Iterative X-Ray Computed Tomography
摘要： High-attenuation materials pose significant challenges to computed tomographic (CT) imaging. Formed of high mass-density and high atomic number elements, they cause more severe beam hardening and scattering artifacts than do water-like materials. Pre-corrected line-integral density measurements are no longer linearly proportional to the path lengths, leading to reconstructed image suffering from streaking artifacts extending from metal, often along highest-density directions. In this paper, a novel prior-based iterative approach is proposed to reduce metal artifacts. It combines the superiority of statistical methods with the benefits of sinogram completion methods to estimate and correct metal-induced biases. Preliminary results show minimized residual artifacts and significantly improved image quality.
关键词： statistical reconstruction,metal artifact reduction,beam hardening correction,computed tomography,iterative reconstruction
更新于2025-09-23 15:19:57
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Computed tomography criteria for the use of advanced localization techniques in minimally invasive thoracoscopic lung resection
摘要： Background: The significant improvement of patient outcomes from minimally invasive lung surgery has led to the development of advanced lung nodule localization techniques to help manage patients with small suspicious lung nodules or to help resect patients with small pulmonary metastases. However, there are no clear computed tomography (CT) criteria to guide the use of advanced localization techniques for this group of patients. Methods: We conducted a retrospective chart review of patients who had undergone initial wedge resection of single or multiple lung nodules. We collected demographics, surgical information and surgical outcomes as well as CT scan features. Multiple logistic regression was performed to determine which factors were most predictive of the need for advanced localization techniques. Results: A total of 45 patients (73%) were resected by direct identification alone while 17 patients (27%) required advanced localization techniques. Of those requiring advanced localization, 11 patients had cone beam CT, 3 patients had transbronchial localization using electromagnetic navigation and 3 patients had preoperative CT guided wire localization. Patients requiring advanced localization had significantly smaller lung nodules at 0.8 cm compared to 1.4 cm (P=0.01), nodules that were further away from the pleura at 1.3 cm compared 0.1 cm (P<0.001) and were more likely to have ground glass nodules (P=0.01) compared to patients who were resected by direct identification alone. Multiple logistic regression confirmed that nodule size, distance to pleura and ground glass attenuation were predictive factors for requiring advanced localizing techniques. Every patient was treated with minimally invasive lung resection. A 1.3-cm or greater solitary pulmonary nodule less than 5 mm from the pleura can be removed without advanced techniques with a 96% success rate. Conclusions: Overall, in patients undergoing resection of a suspicious primary or metastatic lung nodule, advanced localization techniques should be considered in those with small non-solid nodules, which are not near the pleural surface on CT scan.
关键词： computed tomography guided localization (CT guided localization),navigation bronchoscopy,cone beam computed tomography (cone beam CT),lung cancer,Lung nodule
更新于2025-09-19 17:15:36
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Diagnostic performance of fluorine-18 fluorodeoxyglucose positron emission tomography in the management of solitary pulmonary nodule: a meta-analysis
摘要： Background: In the setting of solitary pulmonary nodules (SPNs), fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) is considered a useful non-invasive diagnostic tool though false positive (FP) and false negative (FN) results affects accuracy due to different conditions, such as inflammatory diseases or low-uptake neoplasms. Aim of this study is to evaluate overall diagnostic performance of 18F-FDG-PET/CT for malignant pulmonary nodules. Methods: A computerized research, including published articles from 2012 and 2017, was carried out. 18F-FDG-PET/CT overall sensitivity (Se), specificity (Spe), positive likelihood ratio (PLR), negative likelihood ratio (NLR), positive predictive value (PPV), negative predictive value (NPV), diagnostic index and odds ratio were pooled. No selection-bias were found according to asymmetry test. Results: A total of twelve studies were included in the meta-analysis. The pooled Se, Spe, PLR, NLR, PPV, NPV and accuracy index (AI) with relative 95% confidence intervals (CI) were 0.819 (95% CI: 0.794–0.843), 0.624 (95% CI: 0.582–0.665), 2.190 (95% CI: 1.950–2.440), 0.290 (95% CI: 0.250–0.330), 0.802 (95% CI: 0.783–0.819), 0.652 (95% CI: 0.618–0.684) and 0.649 (95% CI: 0.625–0.673), respectively. The diagnostic odds ratio (DOR) was 7.049 with a relative 95% CI between 5.550 and 8.944. Conclusions: The results suggest 18F-FDG-PET/CT has good diagnostic accuracy in SPNs evaluation; but, it should not be considered as a discriminatory test rather than a method to be included in a clinical and diagnostic pathway.
关键词： Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT),solitary pulmonary nodules (SPNs),lung cancer
更新于2025-09-19 17:15:36
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Bayesian 3D X-Ray Computed Tomography with a Hierarchical Prior Model for Sparsity in Haar Transform Domain
摘要： In this paper, a hierarchical prior model based on the Haar transformation and an appropriate Bayesian computational method for X-ray CT reconstruction are presented. Given the piece-wise continuous property of the object, a multilevel Haar transformation is used to associate a sparse representation for the object. The sparse structure is enforced via a generalized Student-t distribution (S tg), expressed as the marginal of a normal-inverse Gamma distribution. The proposed model and corresponding algorithm are designed to adapt to specific 3D data sizes and to be used in both medical and industrial Non-Destructive Testing (NDT) applications. In the proposed Bayesian method, a hierarchical structured prior model is proposed, and the parameters are iteratively estimated. The initialization of the iterative algorithm uses the parameters of the prior distributions. A novel strategy for the initialization is presented and proven experimentally. We compare the proposed method with two state-of-the-art approaches, showing that our method has better reconstruction performance when fewer projections are considered and when projections are acquired from limited angles.
关键词： Haar transformation,X-ray computed tomography,generalized Student-t distribution,hierarchical structure,inverse problem,sparsity
更新于2025-09-19 17:15:36
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CT/MRI-Guided Synergistic Radiotherapy and X-ray Inducible Photodynamic Therapy Using Tb-Doped Gd-W-Nanoscintillators
摘要： The use of X-rays instead of UV/Vis light to trigger photodynamic therapy, named X-ray inducible photodynamic therapy, holds tremendous promise due to a high penetration capacity in tissues and is worthy of in-depth study. In this study, a novel multifunctional nanoagent based on Merocyanine 540-coupled Gd2(WO4)3:Tb nanoscintillators and the vitalization of its abilities for dual-modal computed tomography and the magnetic-resonance-imaging-guided synergistic radio-/X-ray inducible photodynamic therapy of tumors is reported. Synergistic therapies show a higher tumor growth inhibition efficiency at a lower X-ray dose than radiotherapy alone. Through this proof-of-concept work, a way to tactfully understand and utilize nanoscintillators for cancer theranostics is shown.
关键词： nanoscintillators,radiotherapy,magnetic resonance imaging,computed tomography,X-ray inducible photodynamic therapy
更新于2025-09-19 17:15:36