Biomedical Imaging Division, VT / WFU SBES
Publications
AAAS EurekAlert! Interview with Dr. Ge Wang
5 months ago
Dr. Ge Wang was interviewed by The American Association for the Advancement of Science (AAAS) regarding Omni-Tomography. The article can be found at the following link.
Dr. Ge Wang Featured on VT Engineering Website
7 months ago
Dr. Ge Wang’s research on has been featured by Virginia Tech’s Engineering Department website.
Omni-Tomography Featured by MedicalPhysicsWeb
7 months ago
“Towards Omni-Tomography—Grand Fusion of Multiple Modalities for Simultaneous Interior Tomography” has been featured by MedicalPhysicsWeb.
Omni-Tomography Paper Published in PLoSONE
10 months ago
Paper can be freely accessed at PLoSONE website.
Abstract:
We recently elevated interior tomography from its origin in computed tomography (CT) to a general tomographic principle, and proved its validity for other tomographic modalities including SPECT, MRI, and others. Here we propose “omni-tomography”, a novel concept for the grand fusion of multiple tomographic modalities for simultaneous data acquisition in a region of interest (ROI). Omni-tomography can be instrumental when physiological processes under investigation are multi-dimensional, multi-scale, multi-temporal and multi-parametric. Both preclinical and clinical studies now depend on in vivo tomography, often requiring separate evaluations by different imaging modalities. Over the past decade, two approaches have been used for multimodality fusion: Software based image registration and hybrid scanners such as PET-CT, PET-MRI, and SPECT-CT among others. While there are intrinsic limitations with both approaches, the main obstacle to the seamless fusion of multiple imaging modalities has been the bulkiness of each individual imager and the conflict of their physical (especially spatial) requirements. To address this challenge, omni-tomography is now unveiled as an emerging direction for biomedical imaging and systems biomedicine.
Call for Papers: SPIE 2012 – Developments in X-Ray Tomography
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Developments in X-Ray Tomography VIII (OP325)
Part of the SPIE International Symposium on SPIE Optical Engineering + Applications
12–16 August 2012 • San Diego Convention Center • San Diego, CA United States
Conference Chairs: Stuart R. Stock, Northwestern Univ. (United States)
Program Committee: Felix Beckmann, Helmholtz-Zentrum Geesthacht (Germany); Graham R. Davis, Queen
Mary, Univ. of London (United Kingdom); Atsushi Momose, The Univ. of Tokyo (Japan); Bert Müller, Univ.
Basel (Switzerland); Andrew G. Peele, Australian Synchrotron (Australia) and La Trobe Univ. (Australia); Erik
L. Ritman, Mayo Clinic (United States); Mark L. Rivers, The Univ. of Chicago (United States); Ge Wang,
Virginia Polytechnic Institute and State Univ. (United States)
NSF CAREER Award Winner: Dr. Hengyong Yu
01 year ago
We are pleased to announce a 2012 NSF CAREER Award Winner: Dr. Hengyong Yu
While classic computed tomography (CT) theory targets exact reconstruction of a whole cross-section or entire volume from complete projections, biomedical applications often focus on relatively small internal region-of-interests (ROIs). However, traditional CT theory cannot exactly reconstruct an internal ROI only from truncated projections associated with x-rays through the ROI because this interior problem does not have a unique solution in an unconstrained setting. In 2007, the PI and his collaborators proved that the interior problem can be exactly and stably solved if a sub-region is known inside the ROI. Inspired by the compressive sensing (CS) theory, in 2009 the PI proposed the concept of CS-based interior tomography and proved that exact interior reconstruction is achievable with an interior scan if the ROI is piecewise constant, which is subsequently extended to the case of piecewise polynomial ROI.
The goal of this CAREER proposal is to advance the CS-based interior tomography theory and algorithms, and make a paradigm shift from traditional global filtered back-projection (FBP) to contemporary interior reconstruction.
The three objectives are to 1) perform mathematical analysis on a general scarcity constraint model to establish uniqueness, exactness and stability, as well as the properties of the corresponding discrete scheme; 2) develop and optimize novel interior reconstruction algorithms in a general POCS framework incorporating the split-Bregman and statistical reconstruction methods; 3) verify the theoretical findings and validate the proposed algorithms via numerical simulation, and demonstrate its utility by solving the big patient problem.
The research will be closely integrated with educational and outreach activities including creating a Medical Image Reconstruction course at both graduate and undergraduate levels at the Virginia Tech-Wake Forest University School of Biomedical Engineering and Sciences (SBES).
US Patent Issued: Systems and Methods for Bioluminescent CT Reconstruction
1 year ago
Dr. Ge Wang was recently issued US Patent No. 8.090,431 on 1/3/2012. Click here for full PDF.
Yang J, Vannier M, Wang F, Deng Y, Ou F, Bennett J, Liu Y, Wang G: Scientific Productivity, Research Funding, Race and Ethnicity. arXiv:1112.3944, 2011
01 year ago
In a recent study by Ginther et al., the probability of receiving a U.S. National Institutes of Health (NIH) RO1 award
was related to the applicant’s race/ethnicity. The results indicate black/African-American applicants were 10% less
likely than white peers to receive an award, after controlling for background and qualifications. It has generated a
widespread debate regarding the unfairness of the NIH grant review process and its correction. In this paper, the
work by Ginther et al. was augmented by pairing analysis, axiomatically-individualized productivity and normalized
funding success measurement. Although there are racial differences in R01 grant success rates, normalized figures
of merit for funding success explain the discrepancy. The suggested “leverage points for policy intervention” are in
question and require deeper and more thorough investigations. Further adjustments in policies to remove racial
disparity should be made more systematically for equal opportunity, rather than being limited to the NIH review
process. Click here for full article…
Shen H, Wang G: Reply to “Comment on ‘A study on tetrahedron-based inhomogeneous Monte-Carlo optical simulation’”
02 years ago
Abstract: We compare the accuracy of TIM-OS and MMCM in response to the recent analysis made by Fang [Biomed. Opt. Express 2, 1258 (2011)]. Our results show that the tetrahedron-based energy deposition algorithm used in TIM-OS is more accurate than the node-based energy deposition algorithm used in MMCM.
Website: https://sites.google.com/a/imaging.sbes.vt.edu/tim-os/home
Shen H, Wang G: A study on tetrahedron-based inhomogeneous Monte-Carlo optical simulation. Biomedical Optics Express, 2(1): 44-57 (2011).
02 years ago
Monte Carlo (MC) simulation is widely recognized as a gold standard in biophotonics for its high accuracy. Here we analyze several issues associated with tetrahedron-based optical Monte Carlo simulation in the context of TIM-OS, MMCM, MCML, and CUDAMCML in terms of accuracy and efficiency. Our results show that TIM-OS has significant better performance in the complex geometry cases and has comparable performance with CUDAMCML in the multi-layered tissue model.
Website: https://sites.google.com/a/imaging.sbes.vt.edu/tim-os/home
Cong W, Wang G, Higher-order phase shift reconstruction approach, Med. Phys. 37, 5238-5242, 2010
02 years ago
Biological soft tissues encountered in clinical and preclinical imaging mainly consists of atoms of light elements with low atomic numbers and their elemental composition is nearly uniform with little density variation. Hence, x-ray attenuation contrast is relatively poor and cannot achieve satisfactory sensitivity and specificity. In contrast, x-ray phase-contrast provides a new mechanism for soft tissue imaging. The x-ray phase shift of soft tissues is about a thousand times greater than the x-ray absorption over the diagnostic x-ray energy range, yielding a higher signal-to-noise ratio than the attenuation contrast counterpart. Thus, phase-contrast imaging is a promising technique to
reveal detailed structural variation in soft tissues, offering a high contrast resolution between healthy and malignant tissues. Here the authors develop a novel phase retrieval method to reconstruct the phase image on the object plane from the intensity measurements. The reconstructed phase image is a projection of the phase shift induced by an object and serves as input to reconstruct the 3D refractive index distribution inside the object using a tomographic reconstruction algorithm. Such x-ray refractive index images can reveal structural features in soft tissues, with excellent resolution differentiating healthy and malignant tissues.Click here for full article…
Axiomatic Index for Teamwork
02 years ago
The number of publications and the number of co-authors become increasingly larger, and the competition for academic resources has intensified over the past years. To optimize the resource allocation, fair, sensitive and quick assessment of individual research productivity is highly desirable and being actively studied. However, the current indices, such as the number of papers, the number of citations, the h-factor and its variants have serious limitations. The primary shortcoming of these indices is their inability to quantify co-authors’ credits. Recently, we established an axiomatic system and derived the measure that is referred to as the a-index for quantification of co-authors’ credits. We believe that our methodology could play a significant role in the recruitment, promotion, funding and other evaluative processes. The a-index technology is patent-pending. Click here for full presentation….
Current collaborators include Dr. Jiansheng Yang, Mr. Ivan Ye, and Dr. Michael Vannier.
Background
In the NY Times best seller, “The Black Swan”, the author (Nassim Nicholas Taleb) defines a Black Swan as an event that has three characteristics: it is an outlier; it carries an extreme impact; it has retrospective predictability. He further makes a claim that our world is dominated by Black Swans. This seminar series will provide an environment in which engineers, scientists and humanists from different disciplines can come together to move beyond the predictable and incremental advances in the current technologies to the disruptive technologies of the future – a breeding ground for future Black Swans.
Lu Y, Zhu B, Shen H, Rasmussen J, Wang G, Sevick-Muraca E: A parallel adaptive finite element simplified spherical harmonics approximation solver for frequency domain fluorescence molecular imaging. Phy. Med. Bio., 55, 4625-4645, 2010
02 years ago
Fluorescence molecular imaging/tomography may play an important future role in preclinical research and clinical diagnostics. Time- and frequency-domain fluorescence imaging can acquire more measurement information than the continuous wave (CW) counterpart, improving the image quality of fluorescence molecular tomography. Although diffusion approximation (DA) theory has been extensively applied in optical molecular imaging, high-order photon migration models need to be further investigated to match quantitation provided by nuclear imaging. In this paper, a frequency-domain parallel adaptive finite element solver is developed with simplified spherical harmonics (SPN) approximations. To fully evaluate the performance of the SPN approximations, a fast time-resolved tetrahedron-based Monte Carlo fluorescence simulator suitable for complex heterogeneous geometries is developed using a convolution strategy to realize the simulation of the fluorescence excitation and emission. The validation results show that high-order SPN can effectively correct the modeling errors of the diffusion equation, especially when the tissues have high absorption characteristics or when high modulation frequency measurements are used. Furthermore, the parallel adaptive mesh evolution strategy improves the modeling precision and the simulation speed significantly on a realistic digital mouse phantom. This solver is a promising platform for fluorescence molecular tomography using high-order approximations to the radiative transfer equation.
Website: https://sites.google.com/a/imaging.sbes.vt.edu/tim-os/home
Hengyong Yu, Changguo Ji, and Ge Wang, SART-Type Image Reconstruction from Overlapped Projections, International Journal of Biomedical Imaging, vol. 2011, Article ID 549537, 7 pages, 2010 [PMCID: PMC2943093]
02 years ago
To maximize the time-integrated X-ray flux from multiple X-ray sources and shorten the data acquisition process, a promising way is to allow overlapped projections from multiple sources being simultaneously on without involving the source multiplexing technology. The most challenging task in this configuration is to perform image reconstruction effectively and efficiently from overlapped projections. Inspired by the single-source simultaneous algebraic reconstruction technique (SART), we hereby develop a multisource SART-type reconstruction algorithm regularized by a sparsity-oriented constraint in the soft-threshold filtering framework to reconstruct images from overlapped projections. Our numerical simulation results verify the correctness of the proposed algorithm and demonstrate the advantage of image reconstruction from overlapped projections.Click here for full article…
Yuchuan Wei, Hengyong Yu, and Ge Wang, Inverse Fourier Transform in the Gamma Coordinate System, International Journal of Biomedical Imaging, vol. 2011, Article ID 285130, 16 pages, 2010 [PMCID: PMC2964910]
02 years ago
This paper provides auxiliary results for our general scheme of computed tomography. In 3D parallel-beam geometry, we first demonstrate that the inverse Fourier transform in different coordinate systems leads to different reconstruction formulas and explain why the Radon formula cannot directly work with truncated projection data. Also, we introduce a gamma coordinate system, analyze its properties, compute the Jacobian of the coordinate transform, and define weight functions for the inverse Fourier transform assuming a simple scanning model. Then, we generate Orlov’s theorem and a weighted Radon formula from the inverse Fourier transform in the new system. Furthermore, we present the motion equation of the frequency plane and the conditions for sharp points of the instantaneous rotation axis. Our analysis on the motion of the frequency plane is related to the Frenet-Serret theorem in the differential geometry.Click here for full article…
Lu Y, Yu H, Cao G, Zhao J, Wang G, Zhou O: Multi-beam field emission x-ray system and its reconstruction algorithm. Medical Physics 37:3773-3781, 2010
02 years ago
In this article, the authors propose a multibeam field emission x-ray MBFEX system along with a half-scan fan-beam reconstruction algorithm. The proposed system consists of a linear CNT-based MBFEX source array, a single large
area detector that is divided into same number of segments as the number of x-ray beams, a multihole collimator that aligns each beam with a corresponding detector segment, and a sample rotation stage. The collimator is placed between the source and the object to restrict the x-ray radiations through the target object only. In this design, all the x-ray beams are activated simultaneously to provide multiple projection views of the object. The detector is virtually segmented and synchronized with the x-ray exposure and the physiological signals when gating is involved. The
transmitted x-ray intensity from each beam is collected by the corresponding segment on the detector. After each exposure, the object is rotated by a step angle until sufficient data set is collected. The half-scan reconstruction formula for MBFEX system is derived from the conventional filtered backprojection algorithm. To demonstrate the advantages of the system and method in reducing motion artifacts, the authors performed simulations with both standard and dynamic Shepp–Logan phantoms.Click here for full article…
Yu H, Wang G, A soft-threshold filtering approach for reconstruction from a limited number of projections, Physics in Medicine and Biology, vol. 55, pg 3905-3916, 2010
02 years ago
In the medical imaging field, discrete gradient transform (DGT) is widely used as a sparsifying operator to define the total variation (TV). Recently, TV minimization has become a hot topic in image reconstruction and is usually
implemented using the steepest descent method (SDM). Since TV minimization with the SDM takes a long computational time, here we construct a pseudoinverse of the DGT and adapt a soft-threshold filtering algorithm, whose convergence and efficiency have been theoretically proven. Also, we construct a pseudo-inverse of the discrete difference transform (DDT) and design an algorithm for L1 minimization of the total difference. These two methods are evaluated in numerical simulation. The results demonstrate the merits of the proposed techniques.
Biomedical Mathematics: Promising Directions in Imaging, Therapy Planning and Inverse Problems
02 years ago
This book brings together 27 state-of-the-art, refereed and subsequently revised, research and review papers, by leading experts and practitioners in mathematical methods in biomedical imaging, in intensity-modulated radiation therapy (IMRT) and in optimization and inverse problems. The emphasis is on trying to discover relations and connections between these fields that will enhance progress in each of them. As this volume shows, applicable mathematical work in these fields goes hand-in-hand with real-world applications and the mutual “technology transfers” between them leads to further progress.
Li L, Chen Z, Jin X, Yu H, Wang G, Experimental measurement of human head motion for high-resolution computed tomography system design, Optical Engineering, vol. 49, n. 6, 2010
02 years ago
Human head motion has been experimentally measured for high-resolution computed tomography (CT) design using a Canon digital camera. Our goal is to identify the minimal movements of the human head under ideal conditions without rigid fixation. In our experiments, all the 19 healthy volunteers were lying down with strict self-control. All of them were asked to be calm without pressures. Our results showed that the mean absolute value of the measured translation excursion was about 0.35 mm, which was much less than the measurements on real patients. Furthermore, the head motions in different directions were correlated. These results are useful for the design of the new instant CT system for in vivo high-resolution imaging (about 40 µm). Click here for full article….