- 标题
- 摘要
- 关键词
- 实验方案
- 产品
过滤筛选
- 2017
- spectral reconstruction
- interference
- polarization
- transform
- imaging spectrometer
- Optoelectronic Information Science and Engineering
- BITTT
- Zhejiang University
- Guilin University of Aerospace Technology
-
[IEEE 2018 International Conference on Radar (RADAR) - Brisbane, Australia (2018.8.27-2018.8.31)] 2018 International Conference on Radar (RADAR) - High-Resolution Radar Imaging with Unknown Noise
摘要： This paper addresses the problem of high-resolution radar imaging in complex environments with unknown noise in a Bayesian framework. In the new statistical model, the noise obeys Gaussian mixture distribution, and the weights are governed by the sparsity-promoting Gamma-Gaussian hierarchical prior. Then, the weights are estimated via the maximum a posterior-expectation maximization (MAP-EM) technique. Experiments have shown that the proposed method provides an effective way of high-resolution radar imaging in complex environments such as barrage jamming.
关键词： Radar imaging,jamming suppression,Bayesian learning,MAP-EM,GMM
更新于2025-09-23 15:22:29
-
A multipurpose X-ray fluorescence scanner developed for in situ analysis
摘要： Over the time, instrument transportability has become more and more important, especially in Cultural Heritage, as often artworks cannot be moved from their site, either because of the size or due to problems with permission issues, or simply because moving them to a laboratory is physically impossible, as e.g. in the case of mural paintings. For this reason, the INFN-CHNet, the network for Cultural Heritage studies of the Italian National Institute of Nuclear Physics (INFN), has developed an XRF scanner for in situ analyses. The instrument is the result of a wide collaboration, where different units of the network have been developing the diverse parts, then merged in a single system. The XRF scanner has been designed to be a four-season and green instrument. The control/acquisition/analysis software has been fully developed by our group, using only open-source software. Other strong points of the system are easiness of use, high portability, good performances and ultra-low radiation dispersion, which allows us to use even when the public can be present. It can run both with mains or on batteries, in the latter case with a maximum runtime longer than 10 h. It has a very low cost, when compared to commercial systems with equivalent performances, and easily replaceable components, which makes it accessible for a much wider portion of the interested community. The system has been thought and designed as an open system, suitable for further development/improvements, that can result interesting for non-conventional XRF analysis. The CHNet XRF scanner has proved to be really very well suited for applications in the Cultural Heritage field, as testified by the many recent applications. This paper describes the present version of our instrument and reports on the tests performed to characterise its main features.
关键词： Transportable instrument,XRF imaging,Acquisition,In situ analysis,Cultural heritage,XRF scanner
更新于2025-09-23 15:22:29
-
A unified framework for plasma data modelling in dynamic Positron Emission Tomography studies
摘要： Objective: Full quantification of dynamic PET data requires the knowledge of tracer concentration in the arterial plasma. However, its accurate measurement is challenging due to the presence of radiolabeled metabolites and measurement noise. Mathematical models are fitted to the plasma data for both radiometabolite correction and data denoising. However, the models used are generally not physiologically informed and not consistently applied across studies even when quantifying the kinetics of the same radiotracer, introducing methodological variability affecting the results interpretation. The aim of this study was to develop and validate a unified framework for the arterial data modelling to achieve an accurate and fully-automated description of the plasma tracer kinetics. Methods: The proposed pipeline employs basis pursuit techniques for estimating both radiometabolites and parent concentration models from the raw plasma measurements, allowing the resulting algorithm to be both robust and flexible to the different quality of data available. The pipeline was tested on four PET tracers ([11C]PBR28, [11C]MePPEP, [11C]WAY-100635 and [11C]PIB) with continuous and discrete blood sampling. Results: Compared to the standard procedure, the pipeline provided similar fit of the parent fraction but yielded a better description of the total plasma radioactivity, which in turn allowed a more accurate fit of the tissue PET data. Conclusion: The new method showed superior fits compared to the standard pipeline, for both continuous and discrete arterial sampling protocol, yielding to better description of PET data. Significance: The proposed pipeline has the potential to standardize the blood data modeling in dynamic PET studies given its robustness, flexibility and easiness of use.
关键词： Kinetic modelling,Positron Emission Tomography,Input function,Receptor imaging
更新于2025-09-23 15:22:29
-
Visualizing Interactions of Circulating Tumor Cell and Dendritic Cell in the Blood Circulation Using In Vivo Imaging Flow Cytometry
摘要： Objective: Visualizing cell interactions in blood circulation is of great importance in studies of anticancer immunotherapy or drugs. However, the lack of a suitable imaging system hampers progress in this field. Methods: In this work, we built a dual-channel in vivo imaging flow cytometer to visualize the interactions of circulating tumor cells (CTCs) and dendritic cells (DCs) simultaneously in the bloodstream. Two artificial neural networks were trained to identify blood vessels and cells in the acquired images. Results and Conclusion: Using this technique, single CTCs and CTC clusters were readily distinguished by their morphology. Interactions of CTCs and DCs were identified, while their moving velocities were analyzed. The CTC-DC clusters moved at a slower velocity than that of single CTCs or DCs. This may provide new insights into tumor metastasis and blood rheology. Significance: This in vivo imaging flow cytometry system holds great potential for assessing the efficiency of targeting CTCs with anticancer immune cells or drugs.
关键词： Cell Interaction,Circulating Tumor Cell,In Vivo Imaging Flow Cytometry,Artificial Neural Network,Dendritic Cell
更新于2025-09-23 15:22:29
-
PET Counting Response Variability Depending on Tumor Location, Activity, and Patient Obesity: A Feasibility Study of Solitary Pulmonary Nodule Using Monte Carlo
摘要： We aim to investigate the counting response variations of Positron Emission Tomography (PET) scanners with different detector configurations in the presence of Solitary Pulmonary Nodule (SPN). Using experimentally validated Monte Carlo simulations, the counting performance of four different scanner models with varying tumor activity, location, and patient obesity is represented using NECR (Noise Equivalent Count Rate). NECR is a well-established quantitative metric which has positive correlation with clinically perceived image quality. The combined effect of tumor displacement and increased activity shows a linear ascending trend for NECR with slope ranges of (12.5–18.2)*10-3 (kBq/cm3)-1 for three-ring (3R) scanners and (15.3–21.5)*10-3 (kBq/cm3)-1 for four-ring (4R). The trend for the combined effect of tumor displacement and patient obesity is exponential decay with 3R configurations weakly dependent on the patient obesity if the tumor is located at the center of the field-of-view with exponent’s range of (6.6-33.8)*10-2 cm-1. The dependency is stronger for 4R scanners (9.6–38.5)*10 -2 cm-1. The analysis indicates that quantitative PET data from the same SPN patient possibly examined in different time points (e.g. during staging or for the evaluation of treatment response) are affected by the different detector configurations and need to be normalized with patient weight, activity, and tumor location to reduce unwanted bias of the diagnosis. Our work provides also with a proof of concept for the ability of properly tuned simulations to provide additional insights into the counting response variability especially in tumor types where often borderline decisions have to be made regarding their characterization.
关键词： image quality assessment,nuclear imaging,lung
更新于2025-09-23 15:22:29
-
Simultaneous Axial Multifocal Imaging using a Single Acoustical Transmission: a Practical Implementation
摘要： Standard ultrasound imaging techniques rely on sweeping a focused beam across a field of view; however, outside the transmission focal depth, image resolution and contrast are degraded. High-quality deep tissue in vivo imaging requires focusing the emitted field at multiple depths, yielding high resolution and high contrast ultrasound images but at the expense of a loss in frame rate. Recent developments in ultrasound technologies have led to user-programmable systems, which enable real-time dynamic control over the phase and apodization of each individual element in the imaging array. In this paper, we present a practical implementation of a method to achieve simultaneous axial multifoci using a single acoustical transmission. Our practical approach relies on the superposition of axial multifoci waveforms in a single transmission. The delay in transmission between different elements is set such that pulses constructively interfere at multiple focal depths. The proposed method achieves lateral resolution similar to successive focusing, but with an enhanced frame rate. The proposed method uses standard dynamic receive beamforming, identical to two-way focusing, and does not require additional post-processing. Thus, the method can be implemented in real-time on programmable ultrasound systems that allow different excitation signals for each element. The proposed method is described analytically and validated by laboratory experiments in phantoms and ex vivo biological samples.
关键词： beamforming,frame rate,multifoci,ultrasound imaging
更新于2025-09-23 15:22:29
-
[IEEE 2018 IEEE International Ultrasonics Symposium (IUS) - Kobe, Japan (2018.10.22-2018.10.25)] 2018 IEEE International Ultrasonics Symposium (IUS) - Feasibility Study of a Coherent Multi-Transducer US Imaging System
摘要： Ultrasound images can be difficult to assess, because of the limited resolution and view-dependent artefacts that are inherent to the small aperture transducers used clinically. An extended aperture has the potential to greatly improve imaging performance. This work introduces a fully coherent multi-transducer ultrasound imaging system, formed by two ultrasound transducers that are synchronized, freely located in space with a common field of view and transmit plane waves. Through coherent combination of the different transducers, a larger effective aperture is obtained and then an improved final image. First phantom images produced using this technique are presented here.
关键词： Large Aperture,Beamforming,Image Resolution,Plane Waves,Ultrasound Imaging
更新于2025-09-23 15:22:29
-
Directionality properties of the nGEM detector of the CNESM diagnostic system for SPIDER
摘要： The ITER project requires additional heating by two neutral beam injectors, each accelerating up to 1 MV a 40 A beam of negative deuterium ions for one hour. Such requirements have never been reached, so it was decided to build in Padova a facility (PRIMA) that hosts two experimental devices: SPIDER, a 100 kV negative H/D RF beam source, and MITICA, a full-scale injector for the ITER NBI. SPIDER has begun operation in 2018, while MITICA is expected to start after 2020. In both devices the accelerated deuterium beam impinges on an actively cooled beam dump used to stop the deuterons. Detection of fusion neutrons produced between beam–deuterons and dump-embedded deuterons will be used as a means to resolve the horizontal beam intensity profile. A neutron detection system called Close-contact Neutron Emission Surface Mapping (CNESM) is installed right behind the SPIDER beam dump, with the aim to provide the neutron emission map of the beam dump surface. The core of this diagnostic system is an nGEM (neutron-Gas Electron Multiplier) detector which will be able to reconstruct the fast neutron beam profile with an efficiency of about 10?4. A crucial point in order to correctly reconstruct the profile of the deposited D? power is the directionality discrimination capability of the detector. This paper reports on the results of the characterization of the nGEM directionality capabilities, performed at the Frascati Neutron Generator (FNG) using 2.5 MeV neutrons, before installation of the detector inside the SPIDER vacuum vessel.
关键词： Neutral beam injector,Directionality,Neutron imaging,GEM detectors,Deuterium map
更新于2025-09-23 15:22:29
-
A correction method for range walk error in time-correlated single-photon counting using photomultiplier tube
摘要： Time-correlated single-photon counting (TCSPC) is one of the most active technologies for optical time-of-flight ranging and three-dimensional (3D) imaging. It has attracted much attention because of its high sensitivity, high ranging accuracy and excellent resolution. TCSPC is applicable for the cases of detecting weak signals, usually for the cases when the detection probability is not higher than 0.01 to 0.1 photons per signal period. However, the reflectivity of the targets to be measured varies greatly in practical applications. Usually the energy of the retuned signal from targets varies over two orders of magnitude. It is unrealistic to dynamically regulate the energy of the laser source at a high frequency to match the reflectivity of targets. A phenomenon of photon pile-up will occur in detecting strong signals, which will lead to a range walk error. The error is particular serious if the pulse width of the laser is relatively wide, such as a nanosecond laser which is extensively used in practical applications. Therefore, investigation of TCSPC under strong returned signal conditions has important significance to extend the application domains of the TCSPC lidar systems. In this paper, ranging accuracy under conditions of different signal intensities using PMT and one-stop TDC is focused on. The photon pile-up caused by the change of amplitude and distortion of reconstructed laser waveform are theoretically analyzed. A correction method for the range walk errors under strong signal situations is proposed and validated in a laser ranging experiment. The results show that, using the correction method, ranging errors can be reduced from 183 mm to 6 mm for the case when the average number of photon is 9.6. The applicable returned signal domain of the TCSPC technique is extended by two orders of magnitude compared to the conventional weak signals. The accuracy and flexibility of TCSPC ranging system will be greatly improved using the proposed error correction method under strong signal conditions.
关键词： Three-dimensional imaging,Lidar,Laser ranging,Photon counting
更新于2025-09-23 15:22:29
-
[IEEE 2018 Wave Electronics and its Application in Information and Telecommunication Systems (WECONF) - Saint-Petersburg, Russia (2018.11.26-2018.11.30)] 2018 Wave Electronics and its Application in Information and Telecommunication Systems (WECONF) - Temperature Measurement Using Endoscopic Acousto-Optical Spectral Imaging System
摘要： The problem of measuring spatial temperature distribution over the surface of hard-to-reach objects with a non-uniform emissivity distribution is considered. We propose to solve it using acousto-optical spectral imaging system. This approach enables precise non-contact temperature measurements as well as contrast visualization in arbitrary narrow spectral bands. The temperature measurement of filament lamp using rigid borescope and acousto-optic imaging filter is presented.
关键词： endoscopy,non-destructive testing,spectral imaging,temperature measurement,acousto-optical tunable filter
更新于2025-09-23 15:22:29