scholarly journals A Single Simulation Platform for Hybrid Photoacoustic and RF-Acoustic Computed Tomography

2018 ◽  
Vol 8 (9) ◽  
pp. 1568 ◽  
Author(s):  
Christopher Fadden ◽  
Sri-Rajasekhar Kothapalli
Keyword(s):  
Computed Tomography ◽  
Numerical Models ◽  
Imaging Systems ◽  
Reconstruction Algorithms ◽  
Finite Element Software ◽  
Thermoacoustic Imaging ◽  
Electromagnetic Absorption ◽  
Breast Phantom ◽  
Molecular Information ◽  
Absorption Contrast

In recent years, multimodal thermoacoustic imaging has demonstrated superior imaging quality compared to other emerging modalities. It provides functional and molecular information, arising due to electromagnetic absorption contrast, at ultrasonic resolution using inexpensive and non-ionizing imaging methods. The development of optical- as well as radio frequency (RF)-induced thermoacoustic imaging systems would benefit from reliable numerical simulations. To date, most numerical models use a combination of different software in order to model the hybrid thermoacoustic phenomenon. Here, we demonstrate the use of a single open source finite element software platform (ONELAB) for photo- and RF-acoustic computed tomography. The solutions of the optical diffusion equation, frequency domain Maxwell’s equations, and time-domain wave equation are used to solve the optical, electromagnetic, and acoustic propagation problems, respectively, in ONELAB. The results on a test homogeneous phantom and an approximate breast phantom confirm that ONELAB is a very effective software for both photo- and RF-acoustic simulations, and invaluable for developing new reconstruction algorithms and hardware systems.

scholarly journals Manual kidney stone size measurements in computed tomography are most accurate using multiplanar image reformatations and bone window settings

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Robert Peter Reimer ◽  
Konstantin Klein ◽  
Miriam Rinneburger ◽  
David Zopfs ◽  
Simon Lennartz ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Treatment Decision ◽  
Reconstruction Algorithm ◽  
Slice Thickness ◽  
Reconstruction Algorithms ◽  
Stone Size ◽  
Bone Window ◽  
3D Printed ◽  
Measurement Strategies ◽  
Digital Caliper

AbstractComputed tomography in suspected urolithiasis provides information about the presence, location and size of stones. Particularly stone size is a key parameter in treatment decision; however, data on impact of reformatation and measurement strategies is sparse. This study aimed to investigate the influence of different image reformatations, slice thicknesses and window settings on stone size measurements. Reference stone sizes of 47 kidney stones representative for clinically encountered compositions were measured manually using a digital caliper (Man-M). Afterwards stones were placed in a 3D-printed, semi-anthropomorphic phantom, and scanned using a low dose protocol (CTDIvol 2 mGy). Images were reconstructed using hybrid-iterative and model-based iterative reconstruction algorithms (HIR, MBIR) with different slice thicknesses. Two independent readers measured largest stone diameter on axial (2 mm and 5 mm) and multiplanar reformatations (based upon 0.67 mm reconstructions) using different window settings (soft-tissue and bone). Statistics were conducted using ANOVA ± correction for multiple comparisons. Overall stone size in CT was underestimated compared to Man-M (8.8 ± 2.9 vs. 7.7 ± 2.7 mm, p < 0.05), yet closely correlated (r = 0.70). Reconstruction algorithm and slice thickness did not significantly impact measurements (p > 0.05), while image reformatations and window settings did (p < 0.05). CT measurements using multiplanar reformatation with a bone window setting showed closest agreement with Man-M (8.7 ± 3.1 vs. 8.8 ± 2.9 mm, p < 0.05, r = 0.83). Manual CT-based stone size measurements are most accurate using multiplanar image reformatation with a bone window setting, while measurements on axial planes with different slice thicknesses underestimate true stone size. Therefore, this procedure is recommended when impacting treatment decision.

Analysis of Pipe-Soil Interaction for a Miniature Pipejacking

2006 ◽  
Vol 22 (3) ◽  
pp. 213-220 ◽  
Author(s):  
K. J. Shou ◽  
F. W. Chang
Keyword(s):  
Finite Element ◽  
Failure Mechanism ◽  
Physical Modeling ◽  
Driving Force ◽  
Numerical Models ◽  
Surface Subsidence ◽  
Finite Element Software

AbstractIn this study, physical and numerical models were used to analyze pipe-soil interaction during pipejacking work. After calibrating with the physical modeling results, the finite element software ABAQUS [1] was used to study the pipejacking related behavior, such as surface subsidence, failure mechanism, pipe-soil interaction, etc. The results show that the driving force in the tunnelling face is very important and critical for pipejacking. Surface subsidence is mainly due to the lack of driving force, however, excessive driving force could cause the unfavorable surface heaving problem. It also suggests that the depth of the pipe is critical to determine a proper driving force to stabilize the tunnelling face.

Isotope computed tomography using cone-beam geometry: a comparison of two reconstruction algorithms

1987 ◽  
Vol 32 (10) ◽  
pp. 1221-1235 ◽  
Author(s):  
A Horsman ◽  
J Sutcliffe ◽  
L Burkinshaw ◽  
P Wild ◽  
J Skilling ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Cone Beam ◽  
Reconstruction Algorithms ◽  
Beam Geometry

scholarly journals Combining Acceleration Techniques for Low-Dose X-Ray Cone Beam Computed Tomography Image Reconstruction

2017 ◽  
Vol 2017 ◽  
pp. 1-10
Author(s):  
Hsuan-Ming Huang ◽  
Ing-Tsung Hsiao
Keyword(s):  
Computed Tomography ◽  
Image Reconstruction ◽  
Low Dose ◽  
Computational Cost ◽  
Reconstruction Algorithm ◽  
Reconstruction Algorithms ◽  
Acceleration Techniques ◽  
Reconstruction Methods ◽  
Speed Up ◽  
Phantom Studies

Background and Objective. Over the past decade, image quality in low-dose computed tomography has been greatly improved by various compressive sensing- (CS-) based reconstruction methods. However, these methods have some disadvantages including high computational cost and slow convergence rate. Many different speed-up techniques for CS-based reconstruction algorithms have been developed. The purpose of this paper is to propose a fast reconstruction framework that combines a CS-based reconstruction algorithm with several speed-up techniques.Methods. First, total difference minimization (TDM) was implemented using the soft-threshold filtering (STF). Second, we combined TDM-STF with the ordered subsets transmission (OSTR) algorithm for accelerating the convergence. To further speed up the convergence of the proposed method, we applied the power factor and the fast iterative shrinkage thresholding algorithm to OSTR and TDM-STF, respectively.Results. Results obtained from simulation and phantom studies showed that many speed-up techniques could be combined to greatly improve the convergence speed of a CS-based reconstruction algorithm. More importantly, the increased computation time (≤10%) was minor as compared to the acceleration provided by the proposed method.Conclusions. In this paper, we have presented a CS-based reconstruction framework that combines several acceleration techniques. Both simulation and phantom studies provide evidence that the proposed method has the potential to satisfy the requirement of fast image reconstruction in practical CT.

scholarly journals Evaluation of Algebraic Iterative Image Reconstruction Methods for Tetrahedron Beam Computed Tomography Systems

2013 ◽  
Vol 2013 ◽  
pp. 1-14
Author(s):  
Joshua Kim ◽  
Huaiqun Guan ◽  
David Gersten ◽  
Tiezhi Zhang
Keyword(s):  
Computed Tomography ◽  
Iterative Reconstruction ◽  
Cone Angle ◽  
Iterative Algorithms ◽  
Projection Data ◽  
Reconstruction Algorithms ◽  
Reconstruction Methods ◽  
Large Cone Angle ◽  
Using Data ◽  
Dual Detector

Tetrahedron beam computed tomography (TBCT) performs volumetric imaging using a stack of fan beams generated by a multiple pixel X-ray source. While the TBCT system was designed to overcome the scatter and detector issues faced by cone beam computed tomography (CBCT), it still suffers the same large cone angle artifacts as CBCT due to the use of approximate reconstruction algorithms. It has been shown that iterative reconstruction algorithms are better able to model irregular system geometries and that algebraic iterative algorithms in particular have been able to reduce cone artifacts appearing at large cone angles. In this paper, the SART algorithm is modified for the use with the different TBCT geometries and is tested using both simulated projection data and data acquired using the TBCT benchtop system. The modified SART reconstruction algorithms were able to mitigate the effects of using data generated at large cone angles and were also able to reconstruct CT images without the introduction of artifacts due to either the longitudinal or transverse truncation in the data sets. Algebraic iterative reconstruction can be especially useful for dual-source dual-detector TBCT, wherein the cone angle is the largest in the center of the field of view.

scholarly journals Dual-Modality Imaging of Cancer with SPECT/CT

2002 ◽  
Vol 1 (6) ◽  
pp. 449-458 ◽  
Author(s):  
Bruce H. Hasegawa ◽  
Kenneth H. Wong ◽  
Koji Iwata ◽  
William C. Barber ◽  
Andrew B. Hwang ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Em Algorithm ◽  
Photon Emission ◽  
Imaging Systems ◽  
Patient Specific ◽  
Emission Computed Tomography ◽  
Functional Information ◽  
Dual Modality ◽  
Photon Attenuation ◽  
Dual Modality Imaging

Dual-modality imaging is an in vivo diagnostic technique that obtains structural and functional information directly from patient studies in a way that cannot be achieved with separate imaging systems alone. Dual-modality imaging systems are configured by combining computed tomography (CT) with radionuclide imaging (using positron emission tomography (PET) or single-photon emission computed tomography (SPECT)) on a single gantry which allows both functional and structural imaging to be performed during a single imaging session without having the patient leave the imaging system. A SPECT/CT system developed at UCSF is being used in a study to determine if dual-modality imaging offers advantages for assessment of patients with prostate cancer using111 In-ProstaScint®, a radiolabeled antibody for the prostate-specific membrane antigen.111 In-ProstaScint® images are reconstructed using an iterative maximum-likelihood expectation-maximization (ML-EM) algorithm with correction for photon attenuation using a patient-specific map of attenuation coefficients derived from CT. The ML-EM algorithm accounts for the dual-photon nature of the111 In-labeled radionuclide, and incorporates correction for the geometric response of the radionuclide collimator. The radionuclide image then can be coregistered and overlaid in color on a grayscale CT image for improved localization of the functional information from SPECT. Radionuclide images obtained with SPECT/CT and reconstructed using ML-EM with correction for photon attenuation and collimator response improve image quality in comparison to conventional radionuclide images obtained with filtered backprojection reconstruction. These results illustrate the potential advantages of dual-modality imaging for improving the quality and the localization of radionuclide uptake for staging disease, planning treatment, and monitoring therapeutic response in patients with cancer.

A feasibility study of time of flight cone beam computed tomography imaging

2021 ◽  
pp. 1-14
Author(s):  
Ignacio O. Romero ◽  
Changqing Li
Keyword(s):  
Computed Tomography ◽  
Cone Beam Computed Tomography ◽  
Time Of Flight ◽  
Cone Beam ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Effects ◽  
Breast Phantom ◽  
Scatter Reduction ◽  
Strong Scattering

BACKGROUND: The time of flight (TOF) cone beam computed tomography (CBCT) was recently shown to reduce the X-ray scattering effects by 95%and improve the image CNR by 110%for large volume objects. The advancements in X-ray sources like in compact Free Electron Lasers (FEL) and advancements in detector technology show potential for the TOF method to be feasible in CBCT when imaging large objects. OBJECTIVE: To investigate feasibility and efficacy of TOF CBCT in imaging smaller objects with different targets such as bones and tumors embedded inside the background. METHODS: The TOF method used in this work was verified using a 24cm phantom. Then, the GATE software was used to simulate the CBCT imaging of an 8 cm diameter cylindrical water phantom with two bone targets using a modeled 20 keV quasi-energetic FEL source and various TOF resolutions ranging from 1 to 1000 ps. An inhomogeneous breast phantom of similar size with tumor targets was also imaged using the same system setup. RESULTS: The same results were obtained in the 24cm phantom, which validated the applied CBCT simulation approach. For the case of 8cm cylindrical phantom and bone target, a TOF resolution of 10 ps improved the image contrast-to-noise ratio (CNR) by 57%and reduced the scatter-to-primary ratio (SPR) by 8.63. For the case of breast phantom and tumor target, image CNR was enhanced by 12%and SPR was reduced by 1.35 at 5 ps temporal resolution. CONCLUSIONS: This study indicates that a TOF resolution below 10 ps is required to observe notable enhancements in the image quality and scatter reduction for small objects around 8cm in diameter. The strong scattering targets such as bone can result in substantial improvements by using TOF CBCT.

scholarly journals Muon Tracing and Image Reconstruction Algorithms for Cosmic Ray Muon Computed Tomography

2019 ◽  
Vol 28 (1) ◽  
pp. 426-435 ◽  
Author(s):  
Zhengzhi Liu ◽  
Stylianos Chatzidakis ◽  
John M. Scaglione ◽  
Can Liao ◽  
Haori Yang ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Image Reconstruction ◽  
Cosmic Ray ◽  
Reconstruction Algorithms ◽  
Image Reconstruction Algorithms

scholarly journals Development of a digital breast phantom for photoacoustic computed tomography

2021 ◽  
Vol 12 (3) ◽  
pp. 1391
Author(s):  
Youwei Bao ◽  
Handi Deng ◽  
Xuanhao Wang ◽  
Hongzhi Zuo ◽  
Cheng Ma
Keyword(s):  
Computed Tomography ◽  
Breast Phantom
Sign in / Sign up

Export Citation Format

Share Document