scholarly journals Employing temporal self-similarity across the entire time domain in computed tomography reconstruction

2015 ◽  
Vol 373 (2043) ◽  
pp. 20140389 ◽  
Author(s):  
D. Kazantsev ◽  
G. Van Eyndhoven ◽  
W. R. B. Lionheart ◽  
P. J. Withers ◽  
K. J. Dobson ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Spatial Resolution ◽  
Temporal Resolution ◽  
Imaging Modality ◽  
Time Lapse ◽  
Frame Rate ◽  
Acquisition Time ◽  
Dynamic Features ◽  
Penalty Term ◽  
Computational Performance

There are many cases where one needs to limit the X-ray dose, or the number of projections, or both, for high frame rate (fast) imaging. Normally, it improves temporal resolution but reduces the spatial resolution of the reconstructed data. Fortunately, the redundancy of information in the temporal domain can be employed to improve spatial resolution. In this paper, we propose a novel regularizer for iterative reconstruction of time-lapse computed tomography. The non-local penalty term is driven by the available prior information and employs all available temporal data to improve the spatial resolution of each individual time frame. A high-resolution prior image from the same or a different imaging modality is used to enhance edges which remain stationary throughout the acquisition time while dynamic features tend to be regularized spatially. Effective computational performance together with robust improvement in spatial and temporal resolution makes the proposed method a competitive tool to state-of-the-art techniques.

scholarly journals Development of Low-Cost Fast Photoacoustic Computed Tomography: System Characterization and Phantom Study

2019 ◽  
Vol 9 (3) ◽  
pp. 374 ◽  
Author(s):  
Mohsin Zafar ◽  
Karl Kratkiewicz ◽  
Rayyan Manwar ◽  
Mohammad Avanaki
Keyword(s):  
Computed Tomography ◽  
Spatial Resolution ◽  
Temporal Resolution ◽  
High Performance ◽  
Low Cost ◽  
Single Element ◽  
Tomography System ◽  
System Characterization ◽  
2D Images ◽  
Fast Rotating

A low-cost Photoacoustic Computed Tomography (PACT) system consisting of 16 single-element transducers has been developed. Our design proposes a fast rotating mechanism of 360o rotation around the imaging target, generating comparable images to those produced by large-number-element (e.g., 512, 1024, etc.) ring-array PACT systems. The 2D images with a temporal resolution of 1.5 s and a spatial resolution of 240 µm were achieved. The performance of the proposed system was evaluated by imaging complex phantom. The purpose of the proposed development is to provide researchers a low-cost alternative 2D photoacoustic computed tomography system with comparable resolution to the current high performance expensive ring-array PACT systems.

scholarly journals Effect of Filtered Back-Projection Filters to Low-Contrast Object Imaging in Ultra-High-Resolution (UHR) Cone-Beam Computed Tomography (CBCT)

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6416
Author(s):  
Sunghoon Choi ◽  
Chang-Woo Seo ◽  
Bo Kyung Cha
Keyword(s):  
Computed Tomography ◽  
High Resolution ◽  
Spatial Frequency ◽  
Spatial Resolution ◽  
Cone Beam Computed Tomography ◽  
Cone Beam ◽  
Acquisition Time ◽  
Imaging Protocol ◽  
Low Contrast ◽  
Smoothing Window

In this study, the effect of filter schemes on several low-contrast materials was compared using standard and ultra-high-resolution (UHR) cone-beam computed tomography (CBCT) imaging. The performance of the UHR-CBCT was quantified by measuring the modulation transfer function (MTF) and the noise power spectrum (NPS). The MTF was measured at the radial location around the cylindrical phantom, whereas the NPS was measured in the eight different homogeneous regions of interest. Six different filter schemes were designed and implemented in the CT sinogram from each imaging configuration. The experimental results indicated that the filter with smaller smoothing window preserved the MTF up to the highest spatial frequency, but larger NPS. In addition, the UHR imaging protocol provided 1.77 times better spatial resolution than the standard acquisition by comparing the specific spatial frequency (f50) under the same conditions. The f50s with the flat-top window in UHR mode was 1.86, 0.94, 2.52, 2.05, and 1.86 lp/mm for Polyethylene (Material 1, M1), Polystyrene (M2), Nylon (M3), Acrylic (M4), and Polycarbonate (M5), respectively. The smoothing window in the UHR protocol showed a clearer performance in the MTF according to the low-contrast objects, showing agreement with the relative contrast of materials in order of M3, M4, M1, M5, and M2. In conclusion, although the UHR-CBCT showed the disadvantages of acquisition time and radiation dose, it could provide greater spatial resolution with smaller noise property compared to standard imaging; moreover, the optimal window function should be considered in advance for the best UHR performance.

scholarly journals Focused X-ray Luminescence Computed Tomography using a Continuous Scanning Scheme

2021 ◽  
Author(s):  
Michael C. Lun ◽  
Yile Fang ◽  
Changqing Li
Keyword(s):  
Computed Tomography ◽  
Imaging System ◽  
Imaging Modality ◽  
Experimental Studies ◽  
Acquisition Time ◽  
Step Size ◽  
Excitation Scheme ◽  
X Ray ◽  
Continuous Scanning ◽  
Scanning Scheme

AbstractX-ray luminescence computed tomography (XLCT) imaging is a hybrid molecular imaging modality combining the merits of both conventional x-ray imaging (high spatial resolution) and optical imaging (high measurement sensitivity). The narrow x-ray beam based XLCT imaging has been shown to be promising. However due to the selective excitation scheme, the imaging speed is slow thus limiting its practical applications for in vivo imaging. In this work, we have introduced a continuous scanning scheme to acquire data for each angular projection in one motion, eliminating the previous stepping scheme and reducing the data acquisition time, which makes it feasible for multiple transverse scans for three-dimensional (3D) imaging. We have introduced a high accuracy vertical stage to our focused x-ray beam based XLCT imaging system to perform high-resolution and 3D XLCT imaging. We have also included a scintillator crystal coupled to a PMT to act as a single-pixel detector for boundary detection purposes to replace our previous flat panel x-ray detector. We have verified the feasibility of our proposed scanning scheme and imaging system by performing phantom experimental studies. A phantom was embedded with a set of cylindrical targets with 200 µm edge-to-edge distance and was scanned in our imaging system with the proposed method. To test the feasibility for 3D scanning, we took measurements from 4 transverse slices with a vertical step size of 1 mm. The results of the experiments verified the feasibility of our proposed method to perform 3D XLCT imaging using a narrow x-ray beam in a reasonable time.

Design of a Calibration Phantom for Measuring the Temporal Resolution of a Tomographic Imaging Device

2007 ◽  
Vol 1 (3) ◽  
pp. 225-232
Author(s):  
Alexander H. Slocum ◽  
Stephen E. Jones ◽  
Rajiv Gupta
Keyword(s):  
Spatial Resolution ◽  
Temporal Resolution ◽  
Planetary Gear ◽  
Tomographic Imaging ◽  
Spatial Modulation ◽  
Acquisition Time ◽  
Input Frequency ◽  
Modulation Transfer ◽  
Imaging Device ◽  
Calibration Phantom

This paper describes the design and development of a calibration phantom to be used to aid in the calculation of the temporal resolution of tomographic imaging devices. Current practice for characterizing the dynamic response of a tomographic imaging device, such as a computed tomography or magnetic resonance imaging machine, uses image acquisition time as a surrogate for temporal resolution. At present, no standard method for describing the temporal resolution of a tomographic imaging device exists. Similar to the spatial modulation transfer function (MTF) used for characterizing spatial resolution, the concept of temporal MTF (t-MTF) can be used to enable characterization of temporal resolution. A scanner’s t-MTF represents the percentage amplitude modulation transfer in the image as a function of the input frequency. The calibration phantom uses slotted disks, each mounted to the rotating ring gear of a planetary gear assembly. The sun gears of each planetary gear set are driven from a common shaft to create differential speed sectors, allowing for about two decades of input frequencies to be obtained using a single motor and driveshaft. Preliminary results show a monotonic decline in the modulation transfer as the input frequency is increased. As expected, there is more modulation transfer at lower frequency and less modulation transfer at high frequency. Analogous to the spatial resolution, one can define the frequency for which there is 10% modulation transfer as the temporal resolution of a scanner.

scholarly journals Deep-Learning Super-Resolution Microscopy Reveals Nanometer-Scale Intracellular Dynamics at the Millisecond Temporal Resolution

2021 ◽  
Author(s):  
Rong Chen ◽  
Xiao Tang ◽  
Zeyu Shen ◽  
Yusheng Shen ◽  
Tiantian Li ◽  
...  
Keyword(s):  
Deep Learning ◽  
Spatial Resolution ◽  
Temporal Resolution ◽  
Single Molecule ◽  
Super Resolution ◽  
Live Cell ◽  
Acquisition Time ◽  
Microtubule Network ◽  
Single Frame ◽  
Super Resolution Microscopy

AbstractSingle-molecule localization microscopy (SMLM) can be used to resolve subcellular structures and achieve a tenfold improvement in spatial resolution compared to that obtained by conventional fluorescence microscopy. However, the separation of single-molecule fluorescence events in thousands of frames dramatically increases the image acquisition time and phototoxicity, impeding the observation of instantaneous intracellular dynamics. Based on deep learning networks, we develop a single-frame super-resolution microscopy (SFSRM) approach that reconstructs a super-resolution image from a single frame of a diffraction-limited image to support live-cell super-resolution imaging at a ∼20 nm spatial resolution and a temporal resolution of up to 10 ms over thousands of time points. We demonstrate that our SFSRM method enables the visualization of the dynamics of vesicle transport at a millisecond temporal resolution in the dense and vibrant microtubule network in live cells. Moreover, the well-trained network model can be used with different live-cell imaging systems, such as confocal and light-sheet microscopes, making super-resolution microscopy accessible to nonexperts.

Multidetector-row Computed Tomography in the Assessment of Coronary Artery Disease – New Techniques and Insights

2010 ◽  
Vol 6 (2) ◽  
pp. 43 ◽  
Author(s):  
Andreas H Mahnken ◽  
Keyword(s):  
Computed Tomography ◽  
Coronary Artery Disease ◽  
Coronary Artery ◽  
Data Acquisition ◽  
Temporal Resolution ◽  
High Temporal Resolution ◽  
Multidetector Row ◽  
Ct Scanners ◽  
Artery Disease ◽  
Cardiac Mdct

Over the last decade, cardiac computed tomography (CT) technology has experienced revolutionary changes and gained broad clinical acceptance in the work-up of patients suffering from coronary artery disease (CAD). Since cardiac multidetector-row CT (MDCT) was introduced in 1998, acquisition time, number of detector rows and spatial and temporal resolution have improved tremendously. Current developments in cardiac CT are focusing on low-dose cardiac scanning at ultra-high temporal resolution. Technically, there are two major approaches to achieving these goals: rapid data acquisition using dual-source CT scanners with high temporal resolution or volumetric data acquisition with 256/320-slice CT scanners. While each approach has specific advantages and disadvantages, both technologies foster the extension of cardiac MDCT beyond morphological imaging towards the functional assessment of CAD. This article examines current trends in the development of cardiac MDCT.

Incidence of Cerebral Hemorrhage in Traumatic Patients using Computed Tomography in Tabuk City, Saudi Arabia

2020 ◽  
Vol 5 (10) ◽  
pp. 460-463
Author(s):  
Amna Mohamed Ahmed ◽  
Towmader Awad ◽  
Hajer Yousif ◽  
Reem Nahari ◽  
Omnia Abdelrhman ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Saudi Arabia ◽  
Head Trauma ◽  
Subdural Hematoma ◽  
Cerebral Hemorrhage ◽  
Imaging Modality ◽  
Common Type ◽  
Radiology Department ◽  
Age Group ◽  
Ct Finding

Computed Tomography (CT) is the most commonly used imaging modality in the evaluation of cerebral hemorrhage in the head trauma patients. Objective: To study the incidence of a cerebral hemorrhage in traumatic patients using computed tomography. Method: This retrospective study was conducted at King Khalid hospital in Tabuk city, Saudi Arabia, in the radiology department, in the period from September 2018 to April 2020. The study was done by collecting 471 CT reports of patients all of them were exposed to head trauma with deferent reasons. The data were analyzed by Statistical Package for the Social Sciences (SPSS) program (ver. 20) and presented in tables and graphs according to the checklist which includes: patient age, gender, type of trauma, CT finding, and type of hemorrhage. Results: The most age group suffered from head trauma was less than 20 years percentage (55%), The male patients more exposed to head trauma than female patients with percentage (84.5%), the road traffic accident (RTA) is the most common type of trauma by percentage (63.5%), according to the CT finding; the cerebral hemorrhage represented (15.5%) with the highest percentage in a subdural hematoma (31.2%), the fracture represented (2.8%) while the normal appearance represented (81.7%) as the highest percentage. Conclusion: Most of the traumatic brain injury in patients caused cerebral hemorrhage and the CT scan reports show that: the common type of cerebral hemorrhage is subdural hematoma and it is common in males which exposed to (RTA) in the age group (21 - 40) years old.

Fault Localization and Functional Testing of ICs by Lock-in Thermography

2002 ◽  
Author(s):  
O. Breitenstein ◽  
J.P. Rakotoniaina ◽  
F. Altmann ◽  
J. Schulz ◽  
G. Linse
Keyword(s):  
Spatial Resolution ◽  
Electronic Device ◽  
Imaging Techniques ◽  
Heat Diffusion ◽  
Acquisition Time ◽  
Temperature Modulation ◽  
Heat Sources ◽  
Ir Camera ◽  
Free Running ◽  
Lock In

Abstract In this paper new thermographic techniques with significant improved temperature and/or spatial resolution are presented and compared with existing techniques. In infrared (IR) lock-in thermography heat sources in an electronic device are periodically activated electrically, and the surface is imaged by a free-running IR camera. By computer processing and averaging the images over a certain acquisition time, a surface temperature modulation below 100 µK can be resolved. Moreover, the effective spatial resolution is considerably improved compared to stead-state thermal imaging techniques, since the lateral heat diffusion is suppressed in this a.c. technique. However, a serious limitation is that the spatial resolution is limited to about 5 microns due to the IR wavelength range of 3 -5 µm used by the IR camera. Nevertheless, we demonstrate that lock-in thermography reliably allows the detection of defects in ICs if their power exceeds some 10 µW. The imaging can be performed also through the silicon substrate from the backside of the chip. Also the well-known fluorescent microthermal imaging (FMI) technique can be be used in lock-in mode, leading to a temperature resolution in the mK range, but a spatial resolution below 1 micron.

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