W-CBTI: A CIR Shift-Based W-Combination Model of Tomography Imaging Method Using a Moving Single Anchor in UWB Systems

A coherence scanning tomographic imaging system with an innovative signal correction method is presented for a critical dimension (CD) measurement of thin film transistor liquid crystal display patterns having multiple focus positions within a single field of view. To facilitate the analyzing of coherence signals, a simulation model based on fast Fourier transform method is proposed, and its simulated result is compared with the coherence signals from the actual experiments. The comparison shows that the majority of frequency characteristics from simulation modeling results are matched with the experimental results. However, in many edge regions, discrepancies in frequency characteristics between the two results are observed. For the interpretation of signals, those are different from the simulation modelling, in that the intensity of its pixels has been corrected by an innovatively proposed connected neighborhoods window method with multiple window sizes. By using this combination of tomographic imaging and edge correction methods, the repeatability of the CD measurement of multiple focus position samples is significantly enhanced compared to the results with a plain two-dimensional optics. The proposed method is also compared with the autofocus methods including gradient magnitude method and frequency domain method and other tomographic imaging methods, including the phase shift method and the Hilbert transform method to show the advantages in the processing time.

This thesis presents a new tomographic imaging method using multiple wavelengths in digital holographic microscopy. It is based on the addition of several reconstructed wavefronts measured at different wavelengths. The resulting diffraction tomographic visibility is then enhanced and the position of the interfaces is determined with ultrahigh precision. Digital holographic microscopy is a method enabling the recording of complex wavefronts and its numerical reconstruction. In our case, it is based on the recording, in off-axis geometry, of the interference between a reference wave and an object wave reflected by a microscopic specimen and magnified by a microscope objective. A couple charged device (CCD) camera records consecutively the resulting holograms at several wavelengths equally separated in the frequency domain. An adapted reconstruction algorithm has been developed to perform an achromatic reconstruction of the different wavefronts. Tomography is then performed by adding the reconstructed wavefronts. Each wavefront phase is individually adjusted to be equal in a given plane of interest. The result of this operation is a constructive addition of complex waves in the selected plane and destructive addition in the others. The amplitude image is attenuated according to a function, called filter function. For perfectly constructive phases no attenuation is present. Varying the plane of interest enables the scan of the object in depth. The obtained diffraction tomographic resolution is better than the one obtained in OCT, with an equivalent spectral width, in low-coherence or short-pulse lasers in optical coherence tomography. Nevertheless, no axial scanning is needed and the shape of the spectrum can be post acquisition tailored. A method is then proposed to enhance the visibility and to precisely determine the position of the interfaces. An axial scan allows the extraction of depth profiles. The maxima detection and a least square fit algorithm are used to perform this enhancement. Moreover, weights are introduced in the addition of the wavefronts, in order to tailor the filter function. Different weights distributions are discussed in terms of separation limit and precision on the interface position. It is shown that position resolution increases for higher separation limit. Finally, the tomographic method has been simplified for cases of a total reflective surface to perform topography. This allows measurements on specimen of several microns high without phase ambiguities. The results are directly measured in optical pathlengths. Experimental measurements have been performed on a specifically designed and homemade target, as well as on a multilayer specimen. Twenty wavelengths in the range of 480-700 nm have been used, resulting in tomographic sections of 725 nm. It is shown that the experimental results perfectly correspond the simulations. Enhanced tomographic results show a separation limit of 725 nm with a position resolution under 130 nm. Measures performed using the Kaiser weight distribution allow a position resolution of a few nanometers, for an increasing separation limit to 3 µm.

Cardiac applications of SPECT or PET imaging and Gated technique have a wide area of use in the field of nuclear cardiology. Throughout the last decade, rapid technological developments have occurred, and additional contributions to the patient administration and the cost-effectiveness of these radionuclide imaging methods have been shown. Regarding single or hybride cardiac imaging, including SPECT and PET methods with or without ECG-gated technique in field of nuclear cardiology with an extensive review, this article presents the current status in the technical background of nuclear tomographic imaging and in the areas of clinical practice, and intends to predict future developments on related patent forms.

Magnetic Particle Imaging (MPI) is a tomographic imaging method that uses magnetic nanoparticles (MNPs) as a tracer. MNPs are made up of unique superparamagnetic behaviour of iron oxide nanoparticle modelled by the Langevin theory. MPI is differed from the structural imaging methods such as Magnetic Resonance Imaging (MRI), Computed Tomographic (CT), Sonography and X-ray. Instead, it is the tracer imaging method like Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT). MPI is a promising potential imaging method for various applications including vascular imaging, cell tracking, hyperthermia, oncology and many more. MPI was first invented in 2005 and now undergoing rapid development by many researchers for clinically use. In this paper, the variability of excitation coil design and performance in MPI will be reviewed. Several issues will be discussed and the new concept of the excitation coil system will be recommended to be explored for future work in MPI.

Interior tomography has been recognized as one of the most effective approaches in computed tomography (CT) to reduce radiation dose rendered to patients. In this work, the authors propose and evaluate an imaging method of radial differential interior tomography. In interior tomography, an x-ray beam is collimated to only irradiate the region of interest (ROI) with suspected lesions while the surrounding area∕volume of normal tissues∕organs is spared. In the proposed imaging method of radial differential interior tomography, the outcome is a ROI image that has gone through a radial differential filtering. The image reconstruction algorithm for the radial differential interior tomography is kept in the fashion of differentiated backprojection and projection onto convex sets, but the required a priori knowledge in a small round area becomes zero and may be more readily available in practice. Using the projection data simulated by computer and acquired by CT scanner, the authors evaluate and verify the performance of the proposed radial differential interior tomography method and its associated image reconstruction algorithm. The preliminary results show that the proposed imaging method can generate an image that is the radial differentiation of a conventional tomographic image and is robust over noise that inevitably exist in practice. It is believed that the proposed imaging method may find its utility in advanced clinical applications wherein a ROI-based image processing and analysis is required for lesion visualization, characterization, and diagnosis.

The metalloexopeptidase CD13/aminopeptidase N (APN) has been shown to be involved in cancer angiogenesis, invasion, and metastasis. Therefore, a CD13/APN-targeted NGR-peptide was labeled with the cyanine dye Cy 5.5 and applied to image tumor xenografts with different APN-expression levels using both planar and tomographic optical imaging methods. In vitro, the peptide-dye conjugate showed a clear binding affinity to APN-positive HT-1080 cells, while negative MCF-7 cells and predosing with the free NGR-peptide revealed little to no fluorescence. In vivo, tumor xenografts (n>or=5) were clearly visualized by two-dimensional (2-D) planar fluorescence reflectance imaging (FRI) and three-dimensional (3-D) fluorescence mediated tomography (FMT) up to 24 h after injection. FMT also allowed us to quantify fluorochrome distribution in deeper tissue sections, showing an average fluorochrome concentration of 306.7+/-54.3 nM Cy 5.5 (HT-1080) and 116.0+/-18.3 nM Cy 5.5 (MCF-7) in the target tissue after 5 h. Competition with the free NGR-peptide resulted in a reduction of fluorochrome concentration in HT-1080 tumor tissue (195.3+/-21.9 nM; 5 h). We thus conclude that NGR-Cy 5.5 combined with novel tomographic optical imaging methods allows us to image and quantify tumor-associated CD13/APN expression noninvasively. This may be a promising strategy for a sensitive evaluation of tumor angiogenesis in vivo.

Optical imaging would be desirable for cancer diagnostics since it can potentially resolve relevant oncological target structures in vivo. We therefore synthesised an alpha v beta(3) targeted fluorochrome and imaged tumour xenografts with different alpha v beta(3) expression levels using both planar and tomographic optical imaging methods. An alpha v beta(3)-targeted RGD peptide was labelled with a cyanine dye (Cy 5.5). Binding of the optical tracer was tested on M21 melanoma (n=5), HT-1080 fibrosarcoma (n=6) and MCF-7 adenocarcinoma (n=5) cells and their tumour xenografts. All optical imaging studies were performed using two-dimensional planar fluorescence reflectance imaging (FRI) technology and three-dimensional fluorescence-mediated tomography (FMT). In vitro, the peptide-dye conjugate showed a clear binding affinity to alpha v beta(3)-positive M21 and HT-1080 cells while alpha v beta(3)-negative MCF-7 cells and pre-dosing with the free RGD peptide revealed little to no fluorescence. In vivo, tumour xenografts were clearly visualised by FRI and FMT up to 24 h post injection. FMT allowed quantification of the fluorochrome distribution in deeper tissue sections showing an average fluorochrome concentration of 417.61 +/- 105.82 nM Cy 5.5 (M21), 353.68 +/- 54.02 nM Cy 5.5 (HT-1080) and 262.83 +/- 155.36 nM Cy 5.5 (MCF-7) in the target tissue 60 min after tracer administration. Competition with the free RGD peptide resulted in a reduction in the fluorochrome concentration in M21 tumour tissue (294.35 +/- 84.27 nM). RGD-Cy 5.5 combined with novel tomographic optical imaging methods allows non-invasive imaging of tumour-associated alpha v beta(3) expression and may thus be a promising strategy for sensitive evaluation of tumour target expression.

Abstract. Introduction. Midface lesions caused by fungal infections are one of the most challenging tasks in modern clinical practice in terms of diagnosis and treatment. In recent years, against the backdrop of increasing cases of invasive fungal diseases, such as mucormycosis, the importance of accurate and timely diagnosis has increased significantly. These infections, often developing in immunocompromised patients, affect both soft tissues and bone structures, making diagnosis particularly important. The aim of the study was to determine the diagnostic value of computed tomography and magnetic resonance imaging methods in the detection and differential diagnosis of midface complications caused by fungal infections, considering their spread to soft tissues and bone structures. Materials and Methods. During a two-year observation period, 40 cases of fungal sinusitis were diagnosed clinically. Among the patients, there were 22 men (55%) and 18 women (45%), aged 47 ± 2 years on average. Standard CT protocols were used for diagnosing with the slice thickness of 1.25 mm, including axial and coronal slices with contrast enhancement. Assessment of disease dynamics was based on changes in the volume of inflammatory processes, bone structure, and surrounding tissues. Magnetic resonance imaging diagnostics were performed on a 1.5 Tesla scanner using standard coils for head and neck. The protocol included axial T1WI, T2WI, T2GRE, FLAIR, and DWI images, as well as contrast-enhanced magnetic resonance angiography to assess vascular changes and pathologies. Results and Discussion. The study analyzed 40 cases of fungal sinusitis confirmed by computed tomography, magnetic resonance imaging, and histological examination. Clinical manifestations, the nature of paranasal sinus involvement, radiological signs, and the frequency of complications were evaluated. The most common pathogens identified were Aspergillus spp. and Penicillium spp., predominantly affecting the maxillary sinus. On computed tomography and magnetic resonance imaging methods, thickening of the mucous membrane, bone destruction, and changes in tissue density were observed. Complications, including osteomyelitis and abscesses, required differential diagnosis with malignant tumors. Conclusions. Computed tomography and magnetic resonance imaging are important diagnostic methods for fungal sinusitis, allowing the identification of changes in sinus structures, bones, and soft tissues, as well as the assessment of the infection spread, which helps prevent complications and improve treatment outcomes.

A method of tomographic imaging is proposed in which two-wave mixing in a photorefractive crystal is used with wavelength scanning of a laser diode and phase modulation of the pump beam. This method provides full optical processing and is effective for weak light from objects because of the use of two-wave mixing. The depth resolution of the method was ~1 cm when the wavelength-scanning width was ~0.02 nm .

The method of tomographic imaging using multi-simultaneous measurements (TIMes) for flame emission reconstructions is presented. Measurements of the peak natural CH* chemiluminescence in the flame and luminescence from different vaporised alkali metal salts that were seeded in a multi-annulus burner were used. An array of 29 CCD cameras around the Cambridge-Sandia burner was deployed, with 3 sets of cameras each measuring a different colour channel using bandpass optical filters. The three-dimensional instantaneous and time-averaged fields of the individual measured channels were reconstructed and superimposed for two new operating conditions, with differing cold flow Reynolds numbers. The contour of the reconstructed flame front followed the interface between the burnt side of the flame, where the alkali salt luminescence appears, and the cold gas region. The increased mixing between different reconstructed channels in the downstream direction that is promoted by the higher levels of turbulence in the larger Reynolds number case was clearly demonstrated. The TIMes method enabled combustion zones originating from different streams and the flame front to be distinguished and their overlap regions to be identified, in the entire volume.

This paper considers a time domain ultrasonic tomographic imaging method in a multi-static configuration using the propagation and backpropagation (PBP) method. Under this imaging configuration, ultrasonic excitation signals from the sources probe the object imbedded in the surrounding medium. The scattering signals are recorded by the receivers. Starting from the nonlinear ultrasonic wave propagation equation and using the recorded time domain signals from all the receiver sensors, the object is to be reconstructed. The conventional PBP method is a modified version of the Kaczmarz method that iteratively updates the estimates of the object acoustical potential distribution within the image area. Each source takes turns to excite the acoustical field until all the sources are used. The proposed multi-static image reconstruction method utilizes a significantly reduced number of sources that are simultaneously excited. We consider two imaging scenarios with regard to source positions. In the first scenario, sources are uniformly positioned on the perimeter of the imaging area. In the second scenario, sources are randomly positioned. By numerical experiments we demonstrate that the proposed multi-static tomographic imaging method using the multiple source excitation schemes results in fast reconstruction and achieves high resolution imaging quality.

This paper develops a fast ultrasonic tomographic imaging method in a multiple-input multiple-output (MIMO) configuration using the propagation and backpropagation (PBP) method. By this method, ultrasonic excitation signals from multiple sources are transmitted simultaneously to probe the objects immersed in the medium. The scattering signals are recorded by multiple receivers. Utilizing the nonlinear ultrasonic wave propagation equation and the received time domain scattered signals, the objects are to be reconstructed iteratively in three steps. First, the propagation step calculates the predicted acoustic potential data at the receivers using an initial guess. Second, the difference signal between the predicted value and the measured data is calculated. Third, the backpropagation step computes updated acoustical potential data by backpropagating the difference signal to the same medium computationally. Unlike the conventional PBP method for tomographic imaging where each source takes turns to excite the acoustical field until all the sources are used, the developed MIMO-PBP method achieves faster image reconstruction by utilizing multiple source simultaneous excitation. Furthermore, we develop an orthogonal waveform signaling method using a waveform delay scheme to reduce the impact of speckle patterns in the reconstructed images. By numerical experiments we demonstrate that the proposed MIMO-PBP tomographic imaging method results in faster convergence and achieves superior imaging quality.

FIB-SEM tomography in catalysis and electrochemistry

In this article, we present an X-ray tomographic imaging method that is well suited for pulmonary disease studies in animal models to resolve the full pathway from gas intake to gas exchange. Current state-of-the-art synchrotron-based tomographic phase-contrast imaging methods allow for three-dimensional microscopic imaging data to be acquired non-destructively in scan times of the order of seconds with good soft tissue contrast. However, when studying multi-scale hierarchically structured objects, such as the mammalian lung, the overall sample size typically exceeds the field of view illuminated by the X-rays in a single scan and the necessity for achieving a high spatial resolution conflicts with the need to image the whole sample. Several image stitching and calibration techniques to achieve extended high-resolution fields of view have been reported, but those approaches tend to fail when imaging non-stable samples, thus precluding tomographic measurements of large biological samples, which are prone to degradation and motion during extended scan times. In this work, we demonstrate a full-volume three-dimensional reconstruction of an intact rat lung under immediate post-mortem conditions and at an isotropic voxel size of (2.75 µm)3. We present the methodology for collecting multiple local tomographies with 360° extended field of view scans followed by locally non-rigid volumetric stitching. Applied to the lung, it allows to resolve the entire pulmonary structure from the trachea down to the parenchyma in a single dataset. The complete dataset is available online (https://doi.org/10.16907/7eb141d3-11f1-47a6-9d0e-76f8832ed1b2).

The Earth Occultation Technique (EOT) has been applied to Fermi's Gamma-ray Burst Monitor (GBM) to perform all-sky monitoring for a predetermined catalog of hard X-ray/soft gamma-ray sources. In order to search for sources not in the catalog, thus completing the catalog and reducing a source of systematic error in EOT, an imaging method has been developed -- Imaging with a Differential filter using the Earth Occultation Method (IDEOM). IDEOM is a tomographic imaging method that takes advantage of the orbital precession of the Fermi satellite. Using IDEOM, all-sky reconstructions have been generated for ~sim 4 years of GBM data in the 12-50 keV, 50-100 keV and 100-300 keV energy bands in search of sources otherwise unmodeled by the GBM occultation analysis. IDEOM analysis resulted in the detection of 57 sources in the 12-50 keV energy band, 23 sources in the 50-100 keV energy band, and 7 sources in the 100-300 keV energy band. Seventeen sources were not present in the original GBM-EOT catalog and have now been added. We also present the first joined averaged spectra for four persistent sources detected by GBM using EOT and by the Large Area Telescope (LAT) on Fermi: NGC 1275, 3C 273, Cen A, and the Crab.