EFFECT OF THE BEAM PATTERN ON THE QUALITY OF OBJECT IMAGE RECONSTRUCTION IN CIRCULAR APERTURE SYNTHESIS

2016 ◽  
2020 ◽  
Vol 58 (11) ◽  
pp. 7720-7733
Author(s):  
Yufang Li ◽  
Qingxia Li ◽  
Liangqi Gui ◽  
Li Feng ◽  
Haofeng Dou ◽  
...  

2020 ◽  
Vol 6 (4) ◽  
pp. 18 ◽  
Author(s):  
Sophia Bethany Coban ◽  
Felix Lucka ◽  
Willem Jan Palenstijn ◽  
Denis Van Loo ◽  
Kees Joost Batenburg

In tomographic imaging, the traditional process consists of an expert and an operator collecting data, the expert working on the reconstructed slices and drawing conclusions. The quality of reconstructions depends heavily on the quality of the collected data, except that, in the traditional process of imaging, the expert has very little influence over the acquisition parameters, experimental plan or the collected data. It is often the case that the expert has to draw limited conclusions from the reconstructions, or adapt a research question to data available. This method of imaging is static and sequential, and limits the potential of tomography as a research tool. In this paper, we propose a more dynamic process of imaging where experiments are tailored around a sample or the research question; intermediate reconstructions and analysis are available almost instantaneously, and expert has input at any stage of the process (including during acquisition) to improve acquisition or image reconstruction. Through various applications of 2D, 3D and dynamic 3D imaging at the FleX-ray Laboratory, we present the unexpected journey of exploration a research question undergoes, and the surprising benefits it yields.


2006 ◽  
Author(s):  
Karl-Heinz Hofmann ◽  
Stefan Kraus ◽  
Bruno Lopez ◽  
Gerd Weigelt ◽  
Sebastian Wolf

2020 ◽  
Vol 93 (1110) ◽  
pp. 20190675
Author(s):  
Takuya Ishikawa ◽  
Shigeru Suzuki ◽  
Yoshiaki Katada ◽  
Tomoko Takayanagi ◽  
Rika Fukui ◽  
...  

Objective: The purpose of this study was to evaluate the image quality in virtual monochromatic imaging (VMI) at 40 kilo-electron volts (keV) with three-dimensional iterative image reconstruction (3D-IIR). Methods: A phantom study and clinical study (31 patients) were performed with dual-energy CT (DECT). VMI at 40 keV was obtained and the images were reconstructed using filtered back projection (FBP), 50% adaptive statistical iterative reconstruction (ASiR), and 3D-IIR. We conducted subjective and objective evaluations of the image quality with each reconstruction technique. Results: The image contrast-to-noise ratio and image noise in both the clinical and phantom studies were significantly better with 3D-IIR than with 50% ASiR, and with 50% ASiR than with FBP (all, p < 0.05). The standard deviation and noise power spectra of the reconstructed images decreased in the order of 3D-IIR to 50% ASiR to FBP, while the modulation transfer function was maintained across the three reconstruction techniques. In most subjective evaluations in the clinical study, the image quality was significantly better with 3D-IIR than with 50% ASiR, and with 50% ASiR than with FBP (all, p < 0.001). Regarding the diagnostic acceptability, all images using 3D-IIR were evaluated as being fully or probably acceptable. Conclusions: The quality of VMI at 40 keV is improved by 3D-IIR, which allows the image noise to be reduced and structural details to be maintained. Advances in knowledge: The improvement of the image quality of VMI at 40 keV by 3D-IIR may increase the subjective acceptance in the clinical setting.


2020 ◽  
Vol 12 (10) ◽  
pp. 1645 ◽  
Author(s):  
Roger Oliva ◽  
Manuel Martín-Neira ◽  
Ignasi Corbella ◽  
Josep Closa ◽  
Albert Zurita ◽  
...  

After more than 10 years in orbit, the SMOS team has started a new reprocessing campaign for the SMOS measurements, which includes the changes in calibration and image reconstruction that have been made to the Level 1 Operational Processor (L1OP) during the past few years. The current L1 processor, version v620, was used for the second mission reprocessing in 2014. The new version, v724, is the one run in the third mission reprocessing and will become the new operational processor. The present paper explains the major changes applied and analyses the quality of the data with different metrics. The results have been obtained with numerous individual tests that have confirmed the benefits of the evolutions and an end-to-end processing campaign involving three years of data used to assess the improvements of the SMOS measurements quantitatively.


1979 ◽  
Vol 49 ◽  
pp. 67-82
Author(s):  
J.E. Baldwin ◽  
P.J. Warner

Much ingenuity has been devoted to the determination of mutual coherence functions at radio wavelengths. Measurements of the amplitude and phase of the interference fringes with uncertainties of only 1 percent are now attainable. Unfortunately the atmosphere intervenes between the measured quantities and the mutual coherence function itself and the phase uncertainties introduced by the ionospheric and tropospheric irregularities are often the factor limiting the quality of radioastronomical maps.


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