Application Of Tomography Research Articles

Prototype Cherenkov detector characterization for muon tomography applications

Muography is an innovative imaging technique using naturally produced elementary particles – atmospheric muons – used to determine the distribution of density inside massive objects. The modification of the particles flux – by scattering or absorption – reflects the contrasts in density within the medium and therefore offers the possibility for an image of the crossed volumes. In most muography setups the imaging process is based on the tracking of the particles which accounts for the absorption or the scattering of the muons trajectories. Neither the energy nor the identity of the particles (the so-called PID) is exploited since this information traditionally relies on the use of calorimeters and/or high intensity magnetic fields. Both these techniques hinder detector portability which in the case of muography is important and this renders them impractical for its purpose. In this paper we characterize the performance of a simple and small water Cherenkov detector capable of providing some insights on the energy of muons and the PID for the crossing particles that could potentially improve the background rejection for a muography survey when operating in conjunction with a muon telescope. We tested a prototype of such water Cherenkov detector in combination with two small muon hodoscopes. Both systems are using the same opto-electronics chain – optical fibers and pixellized photosensors – and the same data acquisition (DAQ) readout system which ensures an easy integration and implementation within presently running systems. This article presents the test setup, the detector response to cosmic muons and its performance evaluation against a basic simulation of its geometry and detection principle.

Informationally overcomplete measurements from generalized equiangular tight frames

Informationally overcomplete measurements find important applications in quantum tomography and quantum state estimation. The most popular are maximal sets of mutually unbiased bases, for which trace relations between measurement operators are well known. In this paper, we introduce a more general class of informationally overcomplete positive, operator-valued measure (POVMs) that are generated by equiangular tight frames of arbitrary rank. This class provides a generalization of equiangular measurements to non-projective POVMs, which include rescaled mutually unbiased measurements and bases. We provide a method of their construction, analyze their symmetry properties, and provide examples for highly symmetric cases. In particular, we find a wide class of generalized equiangular measurements that are conical two-designs, which allows us to derive the index of coincidence. Our results show benefits of considering a single informationally overcomplete measurement over informationally complete collections of POVMs.

Modelling of UV Picosecond Laser Interaction with Nanotips for Application in Atom Probe Tomography

Modelling of UV Picosecond Laser Interaction with Nanotips for Application in Atom Probe Tomography

Synthesis and evaluation of bifunctional DFO2K: a modular chelator with ideal properties for zirconium-89 chelation.

The synthesis and evaluation of the newest generation of our DFO2 chelator family-DFO2K-is described. DFO2K was designed with a simple synthetic route to access different bifunctional derivatives, with each derivative having similar metal ion coordination spheres and high denticity (up to 12 coordinate) to ensure stable coordination of zirconium-89. The high denticity could potentially enhance stability with other large oxophilic radiometals. Zirconium-89 is the most popular radionuclide to pair with large macromolecules such as antibodies (immunoPET) for positron emission tomography applications. Although clinically successful, the stability of the "gold standard" chelator desferrioxamine B (DFO) can be improved as significant bone uptake is observed in animal models, despite no obvious stability issues in humans. Following the synthesis of DFO2K we assessed its radiolabeling efficiency with zirconium-89 and compared with DFO, which revealed rapid and nearly identical radiolabeling kinetics to DFO. The resultant [89Zr]Zr-DFO2K complex showed improved stability over [89Zr]Zr-DFO in different in vitro stability assays such as hydroxyapatite and 1000-fold molar excess EDTA challenges. Furthermore, biodistribution studies of the non-bifunctional chelators in healthy mice showed that [89Zr]Zr-DFO2K had a similar distribution profile and clearance to [89Zr]Zr-DFO. The bifunctional derivative p-SCN-Ph-DFO2K was conjugated to a non-specific human IgG antibody and evaluated after 2 weeks circulating in healthy female CD1 mice. Mice administered [89Zr]Zr-DFO2K-IgG showed substantially lower bone uptake in PET-CT images than [89Zr]Zr-DFO-IgG, with PET ROI data and ex vivo biodistribution revealing a statistically significantly lower bone uptake for DFO2K. Overall, owing to its high denticity, ease of synthesis, improved solubility over DFO2 and DFO2p, and stable chelation of zirconium-89, DFO2K appears to be an improved alternative chelator to DFO for zirconium-89 chelation.

Analysis of Water Ice in Nanoporous Copper Needles Using Cryo Atom Probe Tomography.

The application of atom probe tomography (APT) to frozen liquids is limited by difficulties in specimen preparation. Here, we report on the use of nanoporous Cu needles as a physical framework to hold water ice for investigation using APT. Nanoporous Cu needles are prepared by electropolishing and dealloying Cu-Mn matchstick precursors. Cryogenic scanning electron microscopy and focused ion beam milling reveal a hierarchical, dendritic, highly wettable microstructure. The atom probe mass spectrum is dominated by peaks of Cu+ and H(H2O)n+ up to n ≤ 3, and the reconstructed volume shows the protrusion of a Cu ligament into an ice-filled pore. The continuous Cu ligament network electrically connects the apex to the cryostage, leading to an enhanced electric field at the apex and increased cooling, both of which simplify the mass spectrum compared to previous reports.

Ge-Se-Te based penrose photonic quasi-crystal fiber for SCG covering 2–21 μm MIR regime

This work proposes a Penrose-based photonic quasi-crystal fiber (PQF) composed of Arsenic-free, non-toxic chalcogenide glass for Supercontinuum (SC) generation consisting of quasi-crystal lattice of air holes having eight-fold rotational symmetry. Following optimizing the structural parameters, the proposed PQF offers zero dispersion wavelength (ZDW) at around 3.8 μm, an effective mode area of 30 μm2, and a respective high nonlinearity of 824 W−1Km−1 at 2 μm wavelength. By injecting a secant hyperbolic optical pulse having a central wavelength of 4 μm with 20 kW peak power and pulse width of 50 fs, a broadband SC of 2–21 μm is generated, which mostly covers the transparency range of the proposed material as well as Mid-IR regime. To the best of our understanding, this particular type of PQF for broadband SC generation has been proposed for the first time, serving as the novelty factor. Apart from novelty, the wide-band SC assists the proposed PQF in becoming a better counterpart for applications like optical coherence tomography (OCT), frequency metrology, and other Mid-IR applications.

Broadband and fabrication-tolerant 3-dB couplers with topological valley edge modes

3-dB couplers, which are commonly used in photonic integrated circuits for on-chip information processing, precision measurement, and quantum computing, face challenges in achieving robust performance due to their limited 3-dB bandwidths and sensitivity to fabrication errors. To address this, we introduce topological physics to nanophotonics, developing a framework for topological 3-dB couplers. These couplers exhibit broad working wavelength range and robustness against fabrication dimensional errors. By leveraging valley-Hall topology and mirror symmetry, the photonic-crystal-slab couplers achieve ideal 3-dB splitting characterized by a wavelength-insensitive scattering matrix. Tolerance analysis confirms the superiority on broad bandwidth of 48 nm and robust splitting against dimensional errors of 20 nm. We further propose a topological interferometer for on-chip distance measurement, which also exhibits robustness against dimensional errors. This extension of topological principles to the fields of interferometers, may open up new possibilities for constructing robust wavelength division multiplexing, temperature-drift-insensitive sensing, and optical coherence tomography applications.

Application of optical coherence tomography in cardiovascular diseases: bibliometric and meta-analysis.

Since the advent of Optical Coherence Tomography (OCT) two decades ago, there has been substantial advancement in our understanding of intravascular biology. Identifying culprit lesion pathology through OCT could precipitate a paradigm shift in the treatment of patients with Acute Coronary Syndrome. Given the technical prowess of OCT in the realm of cardiology, bibliometric analysis can reveal trends and research focal points in the application of OCT for cardiovascular diseases. Concurrently, meta-analyses provide a more comprehensive evidentiary base, supporting the clinical efficacy of OCT-guided Percutaneous Coronary Intervention (PCI). This study employs a dual approach of Bibliometric and Meta-analysis. Relevant literature from 2003 to 2023 was extracted from the Web of Science Core Collection (WoSCC) and analyzed using VOSviewer, CiteSpace, and R for publication patterns, countries, institutions, authors, and research hotspots. The study compares OCT-guided and coronary angiography-guided PCI in treating adult coronary artery disease through randomized controlled trials (RCTs) and observational studies. The study has been reported in the line with PRISMA and AMSTAR Guidelines. Adhering to inclusion and exclusion criteria, 310 publications were incorporated, demonstrating a continual rise in annual output. Chinese researchers contributed the most studies, while American research wielded greater influence. Analysis of trends indicated that research on OCT and angiography-guided PCI has become a focal topic in recent cohort studies and RCTs. In 11 RCTs (n = 5,277), OCT-guided PCI was not significantly associated with a reduction in the risk of Major Adverse Cardiac Events (MACE) (Odds ratio 0.84, 95% CI 0.65-1.10), cardiac death (0.61, 0.36-1.02), all-cause death (0.7, 0.49-1.02), myocardial infarction (MI) (0.88, 0.69-1.13), target lesion revascularization (TLR) (0.94, 0.7-1.27), target vessel revascularization (TVR) (1.04, 0.76-1.43), or stent thrombosis (0.72, 0.38-1.38). However, in 7 observational studies (n = 4,514), OCT-guided PCI was associated with a reduced risk of MACE (0.66, 0.48-0.91) and TLR (0.39, 0.22-0.68). Our comprehensive review of OCT in cardiovascular disease literature from 2004 to 2023, encompassing country and institutional origins, authors, and publishing journals, suggests that OCT-guided PCI does not demonstrate significant clinical benefits in RCTs. Nevertheless, pooled results from observational studies indicate a reduction in MACE and TLR.

Seeing Double: Can We Reduce The Number Of Cameras In Tomo-PTV?

In this work, we explore the possibility of reducing the number of cameras for tomographic particle tracking velocimetry (PTV) by using beamsplitters to project multiple viewpoints on a single camera sensor. This optical train allows a trade-off between particle seeding density and number of cameras, which enables the reduction of camera cost at the highest end of high-speed tomographic PTV applications where camera cost is considerable. Results are presented with synthetically-generated images for unmodified versions of state-of-the-art PTV algorithms (OpenLPT and DaVis 10.1), and a modification is implemented to the OpenLPT algorithm to include the knowledge that the views are multiplied, enabling the removal of more particles at every iteration of the iterative particle reconstruction (IPR) step. We observe that incorporating the knowledge of the image-multiplied projection brings the performance of the OpenLPT PTV algorithm very close to the baseline performance for equivalent particle seeding density values. However, when using real doubled experimental images we note a major challenge when performing volume self-calibration. The volume self-calibration process is significantly affected by the image doubling, and the knowledge of image doubling has to also be incorporated into the volume self-calibration process, which is left as future work.

Clinical Applications of Handheld Middle Ear Optical Coherence Tomography (ME-OCT) With Live Volumetric Visualization: Clinical Applications of 4D ME-OCT.

Clinical Applications of Handheld Middle Ear Optical Coherence Tomography (ME-OCT) With Live Volumetric Visualization: Clinical Applications of 4D ME-OCT.

A review of Electrical Resistivity Tomography (ERT) applications in non-destructive evaluation of construction materials

A review of Electrical Resistivity Tomography (ERT) applications in non-destructive evaluation of construction materials

Engineering geophysical investigations using electrical resistivity tomography for groundwater exploration in the Bodaibo district of the Irkutsk region

Relevance. The need in technical groundwater exploration to construct a groundwater well for water supply of the rotation village of the mining and processing plant "Svetlovsky" in the Bodaibo district of the Irkutsk region. The electrical resistivity tomography is a common method for studying the upper part of a cross section and is widely used in mineral prospecting, geological mapping, engineering surveys, hydrological and environmental studies. The application of electrical resistivity tomography in these conditions will allow substantiating the location of hydrogeological wells and boreholes. Aim. Assessment of the geological and hydrogeological conditions of the area of work for the prospect of extracting groundwater for technical water supply for the needs of the rotational camp. Objects. Bedrocks, which are characterized by high resistance values and are aquicludes; permeable low-resistance zones that are water-bearing rocks. Methods. Ground-based geophysical surveys using electrical resistivity tomography; two-dimensional inversion of ERT data and their interpretation taking into account engineering and geological data of drilling and the GIS complex. As a result of the engineering and hydrogeological surveys performed using ground-based geophysical surveys by electrical resistivity tomography, it was established that the aquifer system of fissured rocks of the Imnyakh suite of the Proterozoic sediment complex (PR2-3im) is represented by fissured limestones of various colours from grey to blueish, with bands of mica schist. Analysis of the study results showed that the thickness of the exposed sediments is up to 50 m, the groundwater level of the operating horizon is opened at depths from 21 to 28 m. They are covered with a complex of low-permeability sediments of thickness from 5 to 11 m that are presented by interbedding of dense grey limestones and black metasandstones.

Joint reconstruction algorithm: combining synchrotron radiation with conventional X-ray computed tomography for improved imaging

Synchrotron radiation (SR) is an excellent light source for micro-CT (micro-computed tomography) applications due to its monochromaticity and high brightness, which are crucial for achieving high-resolution imaging. However, when scanning larger objects, the limited field of view (FOV) of SR will lead to data truncation, limiting its utilization efficiency. To address this limitation, this paper proposed a method to integrate conventional X-ray CT data to supplement the truncated SR data for joint reconstruction to improve imaging. We first employ a polynomial transformation to match the image gray levels from the two distinct light sources and then resample these to form joint data. Subsequently, the method derives noise images from the noise characteristics of the projection data to construct image weight constraint that accurately reflects different data quality from two sources. The flexibility of the image weight constraint also allows for its combination with various denoisers to further enhance the reconstruction quality. Experimental results demonstrate that the proposed method can leverage the strengths of both imaging modalities to facilitate larger scale and high-resolution imaging.

Efficient Guided Wave Modelling for Tomographic Corrosion Mapping via One-Way Wavefield Extrapolation

Mapping corrosion depths along pipeline sections using guided-wave-based tomographic methods is a challenging task. Accurate defect sizing depends heavily on the precision of the forward model in guided wave tomography. This model is fitted to measured data using inversion techniques. This study evaluates the effectiveness of a recursive extrapolation scheme for tomography applications and full waveform inversion. It employs a table-driven approach, with precomputed extrapolation operators stored across a spectrum of wavenumbers. This enables fast modelling for extensive pipe sections, approaching the speed of ray tracing while accurately handling complex velocity models within the full frequency band. This ensures an accurate representation of diffraction phenomena. The study examines the assumptions underlying the extrapolation approach, namely, the negligible reflection and conversion of modes at defects. In our tomography approach, we intend to use multiple wave modes—A0, S0, and SH1—and helical paths. The acoustic extrapolation method is validated through numerical studies for different wave modes, solving the 3D elastodynamic wave equation. Comparison with an experimentally measured single-mode wavefield from an aluminium plate with an artificial defect reveals good agreement.

Application of ambient noise tomography to coastal granite islands: A case study of Wuzhizhou Island in Hainan, China

Application of ambient noise tomography to coastal granite islands: A case study of Wuzhizhou Island in Hainan, China

A high sensitivity wide bandwidth spectral system for multiple K-edge imaging

Spectral K-edge subtraction (SKES) is an imaging technique that takes advantage of the sharp rise in the mass attenuation coefficient of specific elements within an object at their K-edge to produce separate and quantifiable distributions of each element. In this paper, a high-sensitivity and wide bandwidth SKES imaging system for computed tomography applications on biological samples is presented. X-ray images are acquired using a wide and continuous energy spectrum that encompasses the absorption edges of the target materials. System characterization shows that high energy resolution (approximately 3×10−3 ) and unprecedented large energy bandwidth (around 15%) are achieved over a field-of-view of several centimeters. Imaging results obtained on contrast elements relevant for biomedical applications, namely silver, iodine, xenon, and barium, demonstrate the system sensitivity to concentrations down to 0.5 mg ml−1. The achievement of a large energy bandwidth allowed the simultaneous imaging of the K-edges of iodine, xenon, and barium and provided an accurate concentration estimation and distinction of co-localized contrast elements, leading the way for future simultaneous cardiovascular (iodine), pulmonary (xenon), and gastrointestinal/inflammatory (barium) imaging applications.

In silico intravascular optical coherence tomography (IVOCT) for quality assured imaging with reduced intervention

In the clinical application of intravascular optical coherence tomography (IVOCT), it is necessary to flush opaque blood during image acquisition. However, there are no specific standards for how to perform low-dose but effective flushing. In this study, computational fluid dynamics (CFD) and optical models were integrated to numerically simulate the complete process of IVOCT, which includes blood flushing with normal saline followed by image acquisition. Moreover, an intermittent injection scheme was proposed, and its advantages over the conventionally adopted scheme of continuous injection were verified. The results show that intermittent injection can significantly reduce the dosage of normal saline (reduced by 44.4%) with only a slight sacrifice of image quality (reduced by 8.7%, but still acceptable). The developed model and key findings in this work can help surgeons practice optimized IVOCT operations and potentially lead to improved designs of the IVOCT equipment.

Three-Dimension Epithelial Segmentation in Optical Coherence Tomography of the Oral Cavity Using Deep Learning.

This paper aims to simplify the application of optical coherence tomography (OCT) for the examination of subsurface morphology in the oral cavity and reduce barriers towards the adoption of OCT as a biopsy guidance device. The aim of this work was to develop automated software tools for the simplified analysis of the large volume of data collected during OCT. Imaging and corresponding histopathology were acquired in-clinic using a wide-field endoscopic OCT system. An annotated dataset (n = 294 images) from 60 patients (34 male and 26 female) was assembled to train four unique neural networks. A deep learning pipeline was built using convolutional and modified u-net models to detect the imaging field of view (network 1), detect artifacts (network 2), identify the tissue surface (network 3), and identify the presence and location of the epithelial-stromal boundary (network 4). The area under the curve of the image and artifact detection networks was 1.00 and 0.94, respectively. The Dice similarity score for the surface and epithelial-stromal boundary segmentation networks was 0.98 and 0.83, respectively. Deep learning (DL) techniques can identify the location and variations in the epithelial surface and epithelial-stromal boundary in OCT images of the oral mucosa. Segmentation results can be synthesized into accessible en face maps to allow easier visualization of changes.

ECT in a large scale industrial pneumatic conveying system

The application of electrical capacitance tomography (ECT) for monitoring of industrial processes has been studied and proposed by many researchers. Examples can be found in monitoring of multiphase flows or mixing processes in reactors. Demonstrations of the functionality based on lab and test rig measurements have proven the potential of the proposed principles. This paper discusses the application of an ECT system in a heavy industries application. The harsh operating conditions in the industrial environment pose several challenges for the application of sophisticated measurement technology. This work addresses key aspects for the application of an ECT measurement system in such an environment. Specifically the electrical system design and the influence of the temperature are addressed. Relevant parameters and possible solutions are discussed. Furthermore the application of ECT as instrument for mass flow metering in pneumatic conveying processes is addressed. Supportive measurement studies from test rig experiments and comparative simulation studies are presented. Therefore, the paper provides a concise discussion on the application of ECT under harsh operating conditions, as well as the use of ECT as a measurement device for process measurement. The work concludes with a presentation of a measurement system in an industrial plant in which the proposed concepts were succesfully implemented.

Advances in the Use of Positronic Radiomolecular Imaging Agents in the Diagnosis of Parkinson's Disease

The objective of this study was to examine the potential of positron radioactive molecular imaging agents for the diagnosis of Parkinson's disease (PD). With the increasing prevalence of aging and the rising incidence of PD, early diagnosis is of paramount importance to enhance the quality of life of patients. In terms of research methods, this study analyzed the application of positron emission tomography (PET) and computed tomography (CT) technology and its combination with positron radioactive molecular imaging agents in the diagnosis of Parkinson's disease (PD), with particular emphasis on the use of glucose metabolism imaging agents, including 18F-fluoro-2-deoxy-D-glucose (18F-FDG). The findings of the study demonstrate that the integration of PET/CT technology with positron radioactive molecular imaging agents offers a comprehensive approach to the diagnosis of PD. This approach provides valuable functional and metabolic information about the brain of PD patients, and enables the accurate localization of lesions with high specificity and sensitivity, making it a highly effective and well-tolerated diagnostic tool. The utilization of positron radioactive molecular imaging agents in the diagnosis of PD has the potential to significantly enhance the accuracy and efficiency of diagnosis, thereby facilitating early detection and treatment of PD.