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Di Dong

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University of California, Santa Barbara

University of British Columbia

University College Cork

Kansas State University

Armando Marques-Guedes

UNL - New University of Lisbon

Ucla

Iolanda Craifaleanu

Technical University Of Civil Engineering, Bucharest

Fabián Hoyos Patiño

Universidad Nacional de Colombia (National University of Colombia)

Dimitris P. Drakoulis

Aristotle University of Thessaloniki

University of Sarajevo

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Papers by Di Dong

Non-invasive genotype prediction of chromosome 1p/19q co-deletion by development and validation of an MRI-based radiomics signature in lower-grade gliomas

Journal of neuro-oncology, Jan 10, 2018

To perform radiomics analysis for non-invasively predicting chromosome 1p/19q co-deletion in Worl... more To perform radiomics analysis for non-invasively predicting chromosome 1p/19q co-deletion in World Health Organization grade II and III (lower-grade) gliomas. This retrospective study included 277 patients histopathologically diagnosed with lower-grade glioma. Clinical parameters were recorded for each patient. We performed a radiomics analysis by extracting 647 MRI-based features and applied the random forest algorithm to generate a radiomics signature for predicting 1p/19q co-deletion in the training cohort (n = 184). The clinical model consisted of pertinent clinical factors, and was built using a logistic regression algorithm. A combined model, incorporating both the radiomics signature and related clinical factors, was also constructed. The receiver operating characteristics curve was used to evaluate the predictive performance. We further validated the predictability of the three developed models using a time-independent validation cohort (n = 93). The radiomics signature was ...

Stripe artifact elimination based on nonsubsampled contourlet transform for light sheet fluorescence microscopy

Journal of biomedical optics, Oct 1, 2016

Stripe artifacts, caused by high-absorption or high-scattering structures in the illumination lig... more Stripe artifacts, caused by high-absorption or high-scattering structures in the illumination light path, are a common drawback in both unidirectional and multidirectional light sheet fluorescence microscopy (LSFM), significantly deteriorating image quality. To circumvent this problem, we present an effective multidirectional stripe remover (MDSR) method based on nonsubsampled contourlet transform (NSCT), which can be used for both unidirectional and multidirectional LSFM. In MDSR, a fast Fourier transform (FFT) filter is designed in the NSCT domain to shrink the stripe components and eliminate the noise. Benefiting from the properties of being multiscale and multidirectional, MDSR succeeds in eliminating stripe artifacts in both unidirectional and multidirectional LSFM. To validate the method, MDSR has been tested on images from a custom-made unidirectional LSFM system and a commercial multidirectional LSFM system, clearly demonstrating that MDSR effectively removes most of the str...

A new Pansharp based method for PET/CT image fusion

2014 IEEE 11th International Symposium on Biomedical Imaging (ISBI), 2014

PET/CT image fusion has emerged as a new and promising research area in recent years, whereas the... more PET/CT image fusion has emerged as a new and promising research area in recent years, whereas the current standard method for PET/CT fusion, Alpha-blending, often blurs fine anatomical structure. In this paper, a new fusion method based on the Pansharp model is presented. Our proposed method consists of first up-scaling the PET image to the resolution of the CT data by bilinear interpolation and registering them with mutual information, then integrating the anatomical information into the original PET image and transforming it to a multi-channel RGB image using a color table, and then simulating the panchromatic image with multiple regression analysis, and finally obtaining the fused image according to the Pansharp model. Our method is verified based on 45 real data sets and both qualitative and quantitative analyses of the fusion results demonstrate the effectiveness and robustness of the proposed method.

Three-dimensional multi bioluminescent sources reconstruction based on adaptive finite element method

Medical Imaging 2011: Biomedical Applications in Molecular, Structural, and Functional Imaging, 2011

Among many optical molecular imaging modalities, bioluminescence imaging (BLI) has more and more ... more Among many optical molecular imaging modalities, bioluminescence imaging (BLI) has more and more wide application in tumor detection and evaluation of pharmacodynamics, toxicity, pharmacokinetics because of its noninvasive molecular and cellular level detection ability, high sensitivity and low cost in comparison with other imaging technologies. However, BLI can not present the accurate location and intensity of the inner bioluminescence sources such as in the bone, liver or lung etc. Bioluminescent tomography (BLT) shows its advantage in determining the bioluminescence source distribution inside a small animal or phantom. Considering the deficiency of two-dimensional imaging modality, we developed three-dimensional tomography to reconstruct the information of the bioluminescence source distribution in transgenic mOC-Luc mice bone with the boundary measured data. In this paper, to study the osteocalcin (OC) accumulation in transgenic mOC-Luc mice bone, a BLT reconstruction method based on multilevel adaptive finite element (FEM) algorithm was used for localizing and quantifying multi bioluminescence sources. Optical and anatomical information of the tissues are incorporated as a priori knowledge in this method, which can reduce the ill-posedness of BLT. The data was acquired by the dual modality BLT and Micro CT prototype system that was developed by us. Through temperature control and absolute intensity calibration, a relative accurate intensity can be calculated. The location of the OC accumulation was reconstructed, which was coherent with the principle of bone differentiation. This result also was testified by ex vivo experiment in the black 96-plate well using the BLI system and the chemiluminescence apparatus.

Large Scale Characteristics and Capacity Evaluation of Outdoor Relay Channels at 2.35 GHz

2009 IEEE 70th Vehicular Technology Conference Fall, 2009

Abstract In this paper we present single antenna relay channel measurements conducted in an urban... more

Non-effectively grounded system line selection device based on ARM

2008 China International Conference on Electricity Distribution, 2008

Abstract A hardware and software platform based on ARM (advanced RISC machines) is designed to me... more

<title>Ultrasound-directed robotic system for thermal ablation of liver tumors: a preliminary report</title>

Medical Imaging 2010: Ultrasonic Imaging, Tomography, and Therapy, 2010

Thermal ablation has been proved safe and effective as the treatment for liver tumors that are no... more Thermal ablation has been proved safe and effective as the treatment for liver tumors that are not suitable for resection. Currently, manually performed thermal ablation is greatly dependent on the surgeon's acupuncture manipulation against hand tremor. Besides that, inaccurate or inappropriate placement of the applicator will also directly decrease the final treatment effect. In order to reduce the influence of hand tremor, and provide an accurate and appropriate guidance for a better treatment, we develop an ultrasound-directed robotic system for thermal ablation of liver tumors. In this paper, we will give a brief preliminary report of our system. Especially, three innovative techniques are proposed to solve the critical problems in our system: accurate ultrasound calibration when met with artifacts, realtime reconstruction with visualization using Graphic Processing Unit (GPU) acceleration and 2D-3D ultrasound image registration. To reduce the error of point extraction with artifacts, we propose a novel point extraction method by minimizing an error function which is defined based on the geometric property of our N-fiducial phantom. Then realtime reconstruction with visualization using GPU acceleration is provided for fast D ultrasound volume acquisition with dynamic display of reconstruction progress. After that, coarse 2D-3D ultrasound image registration is performed based on landmark points correspondences, followed by accurate 2D-3D ultrasound image registration based on Euclidean distance transform (EDT). The effectiveness of our proposed techniques is demonstrated in phantom experiments.

Coherent noise remover for optical projection tomography

Medical Imaging 2015: Biomedical Applications in Molecular, Structural, and Functional Imaging, 2015

Optical Projection Tomography (OPT) is a 3-Dimentional (3D) imaging technique for small specimens... more Optical Projection Tomography (OPT) is a 3-Dimentional (3D) imaging technique for small specimens between 1mm and 10mm in size. Due to its high resolution and whole-body imaging ability, OPT has been widely used for imaging of small specimens such as murine embryos, murine organs, zebra fish, and plant sections. During an OPT imaging experiment, the ring artifacts are very common which severely impact the image quality of OPT. A ring artifact is caused by a bad pixel on the camera, or impurities on surface of lens and index matching vessel. Here we term these noises as coherent noise because they stay in the same image region during an OPT experiment. Currently, there is still no effective method to remove coherent noises. To address this problem, we propose a novel method to suppress the coherent noises before 3D OPT reconstruction. Our method consists of two steps: 1) find bad pixel positions on a blank image without specimen by using threshold segmentation, then fix the bad pixels on the projection image by using average of their neighbor pixels, 2) remove remained coherent noises on the sinogram by using Variational Coherent noise Remover (VSNR) method. After the two steps, lots of method can be used to generate the tomographic slices from the modified sinograms. We apply our method to a mouse heart imaging with our home-made OPT system. The experimental results show that our method has a good suppression on coherent noise and greatly improves the image quality. The innovation of our method is that we remove coherent noise automatically from both projection image and sinogram and they complement each other.

Investigation on Flow Field in Shaped Governing Va lve of Steam Tu rbine

AIP Conference Proceedings, 2010

The fluid flow inside turbine governing valve is 3D unsteady turbulence. The interaction between ... more The fluid flow inside turbine governing valve is 3D unsteady turbulence. The interaction between the structure of the valve and the fluid flow may induce vibration of valve disc and valve rod, even more damage. In this article, 3D modeling of the shaped governing valve is established. In the valve calculation and experiment, variation regularity of the flow parameters is

Helical optical projection tomography

Optics Express, 2013

A new technique termed Helical Optical Projection Tomography (hOPT) has been developed with the a... more A new technique termed Helical Optical Projection Tomography (hOPT) has been developed with the aim to overcome some of the limitations of current 3D optical imaging techniques. hOPT is based on Optical Projection Tomography (OPT) with the major difference that there is a translation of the sample in the vertical direction during the image acquisition process, requiring a new approach to image reconstruction. Contrary to OPT, hOPT makes possible to obtain 3D-optical images of intact long samples without imposing limits on the sample length. This has been tested using hOPT to image long murine tissue samples such as spinal cords and large intestines. Moreover, 3D-reconstructed images of the colon of DSS-treated mice, a model for Inflammatory Bowel Disease, allowed the identification of the structural alterations. Finally, the geometry of the hOPT device facilitates the addition of a Selective Plane Illumination Microscopy (SPIM) arm, providing the possibility of delivering high resolution images of selected areas together with complete volumetric information.

Automated Recovery of the Center of Rotation in Optical Projection Tomography in the Presence of Scattering

IEEE Journal of Biomedical and Health Informatics, 2013

Finding the center of rotation is an essential step for accurate 3-D reconstruction in optical pr... more Finding the center of rotation is an essential step for accurate 3-D reconstruction in optical projection tomography. Unfortunately, current methods are not convenient since they require either prior scanning of a reference phantom, small structures of high intensity existing in the specimen, or active participation during the centering procedure. To solve these problems this paper proposes a fast and automatic center of rotation search method making use of parallel programming in graphics processing units. Our method is based on a two step search approach making use only of those sections of the image with high signal-to-noise ratio. We have tested this method both in nonscattering ex vivo samples and in in vivo specimens with a considerable contribution of scattering such as Drosophila melanogaster pupae, recovering in all cases the center of rotation with a precision 1/4 pixel or less.

Analysis of the rotational center location method in Optical Projection Tomography

Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2013

In Optical Projection Tomography (OPT), if the rotational center deviates from the central line o... more In Optical Projection Tomography (OPT), if the rotational center deviates from the central line of the image and this offset is not corrected during the reconstruction, serious blurring will happen in the final 3-dimensional (3D) result. Therefore, the high-precision rotational center location method is very important for OPT. However, existing methods are inconvenient because they need active participation during the location process. Thus, the automated and fast rotational center location method is in great demand. In preliminary work, we proposed an automated rotational center location method which consisted of a high Specimen Signal Intensity (SSI) sinogram selection and a coarse-fine search. Our method had an accuracy of about 1/4 pixel. However, further robustness analysis of our method is lacking. In this paper, we have investigated its location errors on sinograms with various SSIs and analyzed whether it was effective to use high SSI sinograms for rotational center location. Moreover, we have also discussed the relationship between location errors and the starting rotational angles. The experimental results showed that our coarse-fine method was robust under different starting angles. Meanwhile, the high SSI sinogram selection scheme improved the location precision.

Numerical simulation of flow characteristic in three-dimensional bend pipes

Variety of pipes with different types of layout is widely used in enterprise. Flow resistance and... more Variety of pipes with different types of layout is widely used in enterprise. Flow resistance and turbulence is increased by irrational layout of the pipes and flow conditions, and even the pipe system vibration will occur induced probably by fluid disturbance. In this paper, three typical bend pipes in three‐dimension are analyzed from pressure loss and streamline by numerical simulation. The straight and bend section of the pipe is generated and meshed by the hexahedral elements. The quality of meshes is good, and the grid cells are about 300,000. Calculation shows that the first type with the inlet and outlet in opposite direction in one plane has the least resistance coefficient. Therefore, adopting plain layout may be the best choice of the three types mentioned in the paper.

Vertically scanned laser sheet microscopy

Journal of biomedical optics, 2014

Laser sheet microscopy is a widely used imaging technique for imaging the three-dimensional distr... more Laser sheet microscopy is a widely used imaging technique for imaging the three-dimensional distribution of a fluorescence signal in fixed tissue or small organisms. In laser sheet microscopy, the stripe artifacts caused by high absorption or high scattering structures are very common, greatly affecting image quality. To solve this problem, we report here a two-step procedure which consists of continuously acquiring laser sheet images while vertically displacing the sample, and then using the variational stationary noise remover (VSNR) method to further reduce the remaining stripes. Images from a cleared murine colon acquired with a vertical scan are compared with common stitching procedures demonstrating that vertically scanned light sheet microscopy greatly improves the performance of current light sheet microscopy approaches without the need for complex changes to the imaging setup and allows imaging of elongated samples, extending the field of view in the vertical direction.

Preliminary design of a multimodality molecular imaging system

2014 IEEE 11th International Symposium on Biomedical Imaging (ISBI), 2014

We have designed a multimodality molecular imaging system for small animals. The aim is to develo... more We have designed a multimodality molecular imaging system for small animals. The aim is to develop a system which can perform functional imaging, structural imaging, and molecular imaging. Our multimodality system contains five imaging modalities which are Bioluminescence Tomography (BLT), Fluorescence Molecular Tomography (FMT), Cerenkov Luminescence Tomography (CLT), X-ray Computed Tomography (CT), and Positron Emission Tomography (PET). We have designed both the hardware structure and software to make sure multimodality imaging can be achieved. Here we will report the overall design and work flow of the system.

Investigation on the photocatalytic degradation of pyrene on soil surfaces using nanometer anatase TiO2 under UV irradiation

Journal of Hazardous Materials, 2010

Photocatalytic degradation of pyrene on soil surfaces was investigated in the presence of nanomet... more Photocatalytic degradation of pyrene on soil surfaces was investigated in the presence of nanometer anatase TiO 2 under a variety of conditions. After being spiked with pyrene, soil samples loaded with different amounts of TiO 2 (0%, 1%, 2%, 3%, and 4%, w/w) were exposed to UV irradiation for 25 h. The results indicated that the photocatalytic degradation of pyrene followed pseudo-first-order kinetics. TiO 2 accelerated the degradation of pyrene generally as indicated by the half-life reduction from 45.90 to 31.36 h, corresponding to the TiO 2 amounts from 0% to 4%, respectively. The effects of H 2 O 2 , light intensity and humic acids on the degradation of pyrene were also investigated. The degradation of pyrene increased along with increasing the concentration of H 2 O 2 , light intensity and the concentration of humic acids. All results indicated that the photocatalytic method in the presence of nanometer anatase TiO 2 was an advisable choice for the treatments of PAHs polluted soil in the future.

Automated Motion Correction for In Vivo Optical Projection Tomography

IEEE Transactions on Medical Imaging, 2012

In in vivo optical projection tomography (OPT), object motion will significantly reduce the quali... more In in vivo optical projection tomography (OPT), object motion will significantly reduce the quality and resolution of the reconstructed image. Based on the well-known Helgason-Ludwig consistency condition (HLCC), we propose a novel method for motion correction in OPT under parallel beam illumination. The method estimates object motion from projection data directly and does not require any other additional information, which results in a straightforward implementation. We decompose object movement into translation and rotation, and discuss how to correct for both translation and general motion simultaneously. Since finding the center of rotation accurately is critical in OPT, we also point out that the system's geometrical offset can be considered as object translation and therefore also calibrated through the translation estimation method. In order to verify the algorithm effectiveness, both simulated and in vivo OPT experiments are performed. Our results demonstrate that the proposed approach is capable of decreasing movement artifacts significantly thus providing high quality reconstructed images in the presence of object motion.

Fast Katsevich Algorithm Based on GPU for Helical Cone-Beam Computed Tomography

IEEE Transactions on Information Technology in Biomedicine, 2010

Katsevich reconstruction algorithm represents a breakthrough for helical cone-beam computed tomog... more Katsevich reconstruction algorithm represents a breakthrough for helical cone-beam computed tomography (CT) reconstruction, because it is the first exact cone-beam reconstruction algorithm of filtered backprojection (FBP) type with 1-D shiftinvariant filtering. Although FBP-type reconstruction algorithm is effective, 3-D CT reconstruction is time-consuming, and the accelerations of Katsevich algorithm on CPU or cluster have been widely studied. In this paper, Katsevich algorithm is accelerated by using graphics processing unit, including flat-detector and curveddetector geometry in the case of helical orbit. An overscan formula is derived, which helps to avoid unnecessary overscan in practical CT scanning. Based on the overscan formula, a volume-blocking method in device memory is proposed. One advantage of the blocking method is that it can reconstruct large volume with high speed. Index Terms-Computed tomography (CT), graphics processing unit (GPU), Katsevich algorithm, overscan. F ELDKAMP et al. [1] first proposed a 3-D computed to- mography (CT) algorithm of filtered backprojection (FBP) type, which is popular even now because of its efficiency. But it is an approximate algorithm, and it introduces image artifacts that will be aggravated with the increase of cone-beam angle. In 1993, a generalized Feldkamp algorithm was proposed by Wang et al. in the case of helical cone-beam CT, and it is also an approximate algorithm. In recent years, several exact algorithms have been developed, including Katsevich Manuscript

Real-Time Visualized Freehand 3D Ultrasound Reconstruction Based on GPU

IEEE Transactions on Information Technology in Biomedicine, 2010

Visualized freehand 3D ultrasound reconstruction offers to image incremental reconstruction durin... more Visualized freehand 3D ultrasound reconstruction offers to image incremental reconstruction during acquisition and guide users to scan interactively for high quality volumes. We originally used the Graphics Processing Unit (GPU) to develop a visualized reconstruction algorithm that achieves real-time level. Each newly acquired image was transferred to the memory of the GPU and inserted into the reconstruction volume on the GPU. The partially reconstructed volume was then rendered using GPU based incremental ray-casting. After visualized reconstruction, hole-filling was performed on the GPU to fill remaining empty voxels in the reconstruction volume. We examine the real-time nature of the algorithm using in vitro and in vivo data sets. The algorithm can image incremental reconstruction at speed of 26∼58 frames/s and complete 3D imaging in the acquisition time for the conventional freehand 3D ultrasound.

Propagation Characteristics of Wideband Relay Channels in Urban Micro-Cell Environment

IEEE Antennas and Wireless Propagation Letters, 2010

In order to evaluate the performance of a relay system, propagation characteristics of relay chan... more In order to evaluate the performance of a relay system, propagation characteristics of relay channels are necessary, especially in urban micro-cell (UMi) environment. We conducted wideband relay channel measurements at 2.35 GHz in two UMi sites in China by employing a real-time channel sounder. Three types of links-base station to mobile station (BS-MS), relay station to mobile station (RS-MS), and base station to relay station (BS-RS)-were measured separately at three sites. Statistical propagation characteristics are presented and compared in this letter, including path loss (PL), root mean square (rms) delay spread (DS), and angular spread (AS). These results are informative for the technical research and evaluation of the relay system. Index Terms-Angular spread (AS), delay spread (DS), multipleinput-multiple-output (MIMO), path loss (PL), relay, wideband channel measurement.

Non-invasive genotype prediction of chromosome 1p/19q co-deletion by development and validation of an MRI-based radiomics signature in lower-grade gliomas

Journal of neuro-oncology, Jan 10, 2018

To perform radiomics analysis for non-invasively predicting chromosome 1p/19q co-deletion in Worl... more To perform radiomics analysis for non-invasively predicting chromosome 1p/19q co-deletion in World Health Organization grade II and III (lower-grade) gliomas. This retrospective study included 277 patients histopathologically diagnosed with lower-grade glioma. Clinical parameters were recorded for each patient. We performed a radiomics analysis by extracting 647 MRI-based features and applied the random forest algorithm to generate a radiomics signature for predicting 1p/19q co-deletion in the training cohort (n = 184). The clinical model consisted of pertinent clinical factors, and was built using a logistic regression algorithm. A combined model, incorporating both the radiomics signature and related clinical factors, was also constructed. The receiver operating characteristics curve was used to evaluate the predictive performance. We further validated the predictability of the three developed models using a time-independent validation cohort (n = 93). The radiomics signature was ...

Stripe artifact elimination based on nonsubsampled contourlet transform for light sheet fluorescence microscopy

Journal of biomedical optics, Oct 1, 2016

Stripe artifacts, caused by high-absorption or high-scattering structures in the illumination lig... more Stripe artifacts, caused by high-absorption or high-scattering structures in the illumination light path, are a common drawback in both unidirectional and multidirectional light sheet fluorescence microscopy (LSFM), significantly deteriorating image quality. To circumvent this problem, we present an effective multidirectional stripe remover (MDSR) method based on nonsubsampled contourlet transform (NSCT), which can be used for both unidirectional and multidirectional LSFM. In MDSR, a fast Fourier transform (FFT) filter is designed in the NSCT domain to shrink the stripe components and eliminate the noise. Benefiting from the properties of being multiscale and multidirectional, MDSR succeeds in eliminating stripe artifacts in both unidirectional and multidirectional LSFM. To validate the method, MDSR has been tested on images from a custom-made unidirectional LSFM system and a commercial multidirectional LSFM system, clearly demonstrating that MDSR effectively removes most of the str...

A new Pansharp based method for PET/CT image fusion

2014 IEEE 11th International Symposium on Biomedical Imaging (ISBI), 2014

PET/CT image fusion has emerged as a new and promising research area in recent years, whereas the... more PET/CT image fusion has emerged as a new and promising research area in recent years, whereas the current standard method for PET/CT fusion, Alpha-blending, often blurs fine anatomical structure. In this paper, a new fusion method based on the Pansharp model is presented. Our proposed method consists of first up-scaling the PET image to the resolution of the CT data by bilinear interpolation and registering them with mutual information, then integrating the anatomical information into the original PET image and transforming it to a multi-channel RGB image using a color table, and then simulating the panchromatic image with multiple regression analysis, and finally obtaining the fused image according to the Pansharp model. Our method is verified based on 45 real data sets and both qualitative and quantitative analyses of the fusion results demonstrate the effectiveness and robustness of the proposed method.

Three-dimensional multi bioluminescent sources reconstruction based on adaptive finite element method

Medical Imaging 2011: Biomedical Applications in Molecular, Structural, and Functional Imaging, 2011

Among many optical molecular imaging modalities, bioluminescence imaging (BLI) has more and more ... more Among many optical molecular imaging modalities, bioluminescence imaging (BLI) has more and more wide application in tumor detection and evaluation of pharmacodynamics, toxicity, pharmacokinetics because of its noninvasive molecular and cellular level detection ability, high sensitivity and low cost in comparison with other imaging technologies. However, BLI can not present the accurate location and intensity of the inner bioluminescence sources such as in the bone, liver or lung etc. Bioluminescent tomography (BLT) shows its advantage in determining the bioluminescence source distribution inside a small animal or phantom. Considering the deficiency of two-dimensional imaging modality, we developed three-dimensional tomography to reconstruct the information of the bioluminescence source distribution in transgenic mOC-Luc mice bone with the boundary measured data. In this paper, to study the osteocalcin (OC) accumulation in transgenic mOC-Luc mice bone, a BLT reconstruction method based on multilevel adaptive finite element (FEM) algorithm was used for localizing and quantifying multi bioluminescence sources. Optical and anatomical information of the tissues are incorporated as a priori knowledge in this method, which can reduce the ill-posedness of BLT. The data was acquired by the dual modality BLT and Micro CT prototype system that was developed by us. Through temperature control and absolute intensity calibration, a relative accurate intensity can be calculated. The location of the OC accumulation was reconstructed, which was coherent with the principle of bone differentiation. This result also was testified by ex vivo experiment in the black 96-plate well using the BLI system and the chemiluminescence apparatus.

Large Scale Characteristics and Capacity Evaluation of Outdoor Relay Channels at 2.35 GHz

2009 IEEE 70th Vehicular Technology Conference Fall, 2009

Abstract In this paper we present single antenna relay channel measurements conducted in an urban... more

Non-effectively grounded system line selection device based on ARM

2008 China International Conference on Electricity Distribution, 2008

Abstract A hardware and software platform based on ARM (advanced RISC machines) is designed to me... more

<title>Ultrasound-directed robotic system for thermal ablation of liver tumors: a preliminary report</title>

Medical Imaging 2010: Ultrasonic Imaging, Tomography, and Therapy, 2010

Thermal ablation has been proved safe and effective as the treatment for liver tumors that are no... more Thermal ablation has been proved safe and effective as the treatment for liver tumors that are not suitable for resection. Currently, manually performed thermal ablation is greatly dependent on the surgeon's acupuncture manipulation against hand tremor. Besides that, inaccurate or inappropriate placement of the applicator will also directly decrease the final treatment effect. In order to reduce the influence of hand tremor, and provide an accurate and appropriate guidance for a better treatment, we develop an ultrasound-directed robotic system for thermal ablation of liver tumors. In this paper, we will give a brief preliminary report of our system. Especially, three innovative techniques are proposed to solve the critical problems in our system: accurate ultrasound calibration when met with artifacts, realtime reconstruction with visualization using Graphic Processing Unit (GPU) acceleration and 2D-3D ultrasound image registration. To reduce the error of point extraction with artifacts, we propose a novel point extraction method by minimizing an error function which is defined based on the geometric property of our N-fiducial phantom. Then realtime reconstruction with visualization using GPU acceleration is provided for fast D ultrasound volume acquisition with dynamic display of reconstruction progress. After that, coarse 2D-3D ultrasound image registration is performed based on landmark points correspondences, followed by accurate 2D-3D ultrasound image registration based on Euclidean distance transform (EDT). The effectiveness of our proposed techniques is demonstrated in phantom experiments.

Coherent noise remover for optical projection tomography

Medical Imaging 2015: Biomedical Applications in Molecular, Structural, and Functional Imaging, 2015

Optical Projection Tomography (OPT) is a 3-Dimentional (3D) imaging technique for small specimens... more Optical Projection Tomography (OPT) is a 3-Dimentional (3D) imaging technique for small specimens between 1mm and 10mm in size. Due to its high resolution and whole-body imaging ability, OPT has been widely used for imaging of small specimens such as murine embryos, murine organs, zebra fish, and plant sections. During an OPT imaging experiment, the ring artifacts are very common which severely impact the image quality of OPT. A ring artifact is caused by a bad pixel on the camera, or impurities on surface of lens and index matching vessel. Here we term these noises as coherent noise because they stay in the same image region during an OPT experiment. Currently, there is still no effective method to remove coherent noises. To address this problem, we propose a novel method to suppress the coherent noises before 3D OPT reconstruction. Our method consists of two steps: 1) find bad pixel positions on a blank image without specimen by using threshold segmentation, then fix the bad pixels on the projection image by using average of their neighbor pixels, 2) remove remained coherent noises on the sinogram by using Variational Coherent noise Remover (VSNR) method. After the two steps, lots of method can be used to generate the tomographic slices from the modified sinograms. We apply our method to a mouse heart imaging with our home-made OPT system. The experimental results show that our method has a good suppression on coherent noise and greatly improves the image quality. The innovation of our method is that we remove coherent noise automatically from both projection image and sinogram and they complement each other.

Investigation on Flow Field in Shaped Governing Va lve of Steam Tu rbine

AIP Conference Proceedings, 2010

The fluid flow inside turbine governing valve is 3D unsteady turbulence. The interaction between ... more The fluid flow inside turbine governing valve is 3D unsteady turbulence. The interaction between the structure of the valve and the fluid flow may induce vibration of valve disc and valve rod, even more damage. In this article, 3D modeling of the shaped governing valve is established. In the valve calculation and experiment, variation regularity of the flow parameters is

Helical optical projection tomography

Optics Express, 2013

A new technique termed Helical Optical Projection Tomography (hOPT) has been developed with the a... more A new technique termed Helical Optical Projection Tomography (hOPT) has been developed with the aim to overcome some of the limitations of current 3D optical imaging techniques. hOPT is based on Optical Projection Tomography (OPT) with the major difference that there is a translation of the sample in the vertical direction during the image acquisition process, requiring a new approach to image reconstruction. Contrary to OPT, hOPT makes possible to obtain 3D-optical images of intact long samples without imposing limits on the sample length. This has been tested using hOPT to image long murine tissue samples such as spinal cords and large intestines. Moreover, 3D-reconstructed images of the colon of DSS-treated mice, a model for Inflammatory Bowel Disease, allowed the identification of the structural alterations. Finally, the geometry of the hOPT device facilitates the addition of a Selective Plane Illumination Microscopy (SPIM) arm, providing the possibility of delivering high resolution images of selected areas together with complete volumetric information.

Automated Recovery of the Center of Rotation in Optical Projection Tomography in the Presence of Scattering

IEEE Journal of Biomedical and Health Informatics, 2013

Finding the center of rotation is an essential step for accurate 3-D reconstruction in optical pr... more Finding the center of rotation is an essential step for accurate 3-D reconstruction in optical projection tomography. Unfortunately, current methods are not convenient since they require either prior scanning of a reference phantom, small structures of high intensity existing in the specimen, or active participation during the centering procedure. To solve these problems this paper proposes a fast and automatic center of rotation search method making use of parallel programming in graphics processing units. Our method is based on a two step search approach making use only of those sections of the image with high signal-to-noise ratio. We have tested this method both in nonscattering ex vivo samples and in in vivo specimens with a considerable contribution of scattering such as Drosophila melanogaster pupae, recovering in all cases the center of rotation with a precision 1/4 pixel or less.

Analysis of the rotational center location method in Optical Projection Tomography

Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2013

In Optical Projection Tomography (OPT), if the rotational center deviates from the central line o... more In Optical Projection Tomography (OPT), if the rotational center deviates from the central line of the image and this offset is not corrected during the reconstruction, serious blurring will happen in the final 3-dimensional (3D) result. Therefore, the high-precision rotational center location method is very important for OPT. However, existing methods are inconvenient because they need active participation during the location process. Thus, the automated and fast rotational center location method is in great demand. In preliminary work, we proposed an automated rotational center location method which consisted of a high Specimen Signal Intensity (SSI) sinogram selection and a coarse-fine search. Our method had an accuracy of about 1/4 pixel. However, further robustness analysis of our method is lacking. In this paper, we have investigated its location errors on sinograms with various SSIs and analyzed whether it was effective to use high SSI sinograms for rotational center location. Moreover, we have also discussed the relationship between location errors and the starting rotational angles. The experimental results showed that our coarse-fine method was robust under different starting angles. Meanwhile, the high SSI sinogram selection scheme improved the location precision.

Numerical simulation of flow characteristic in three-dimensional bend pipes

Variety of pipes with different types of layout is widely used in enterprise. Flow resistance and... more Variety of pipes with different types of layout is widely used in enterprise. Flow resistance and turbulence is increased by irrational layout of the pipes and flow conditions, and even the pipe system vibration will occur induced probably by fluid disturbance. In this paper, three typical bend pipes in three‐dimension are analyzed from pressure loss and streamline by numerical simulation. The straight and bend section of the pipe is generated and meshed by the hexahedral elements. The quality of meshes is good, and the grid cells are about 300,000. Calculation shows that the first type with the inlet and outlet in opposite direction in one plane has the least resistance coefficient. Therefore, adopting plain layout may be the best choice of the three types mentioned in the paper.

Vertically scanned laser sheet microscopy

Journal of biomedical optics, 2014

Laser sheet microscopy is a widely used imaging technique for imaging the three-dimensional distr... more Laser sheet microscopy is a widely used imaging technique for imaging the three-dimensional distribution of a fluorescence signal in fixed tissue or small organisms. In laser sheet microscopy, the stripe artifacts caused by high absorption or high scattering structures are very common, greatly affecting image quality. To solve this problem, we report here a two-step procedure which consists of continuously acquiring laser sheet images while vertically displacing the sample, and then using the variational stationary noise remover (VSNR) method to further reduce the remaining stripes. Images from a cleared murine colon acquired with a vertical scan are compared with common stitching procedures demonstrating that vertically scanned light sheet microscopy greatly improves the performance of current light sheet microscopy approaches without the need for complex changes to the imaging setup and allows imaging of elongated samples, extending the field of view in the vertical direction.

Preliminary design of a multimodality molecular imaging system

2014 IEEE 11th International Symposium on Biomedical Imaging (ISBI), 2014

We have designed a multimodality molecular imaging system for small animals. The aim is to develo... more We have designed a multimodality molecular imaging system for small animals. The aim is to develop a system which can perform functional imaging, structural imaging, and molecular imaging. Our multimodality system contains five imaging modalities which are Bioluminescence Tomography (BLT), Fluorescence Molecular Tomography (FMT), Cerenkov Luminescence Tomography (CLT), X-ray Computed Tomography (CT), and Positron Emission Tomography (PET). We have designed both the hardware structure and software to make sure multimodality imaging can be achieved. Here we will report the overall design and work flow of the system.

Investigation on the photocatalytic degradation of pyrene on soil surfaces using nanometer anatase TiO2 under UV irradiation

Journal of Hazardous Materials, 2010

Photocatalytic degradation of pyrene on soil surfaces was investigated in the presence of nanomet... more Photocatalytic degradation of pyrene on soil surfaces was investigated in the presence of nanometer anatase TiO 2 under a variety of conditions. After being spiked with pyrene, soil samples loaded with different amounts of TiO 2 (0%, 1%, 2%, 3%, and 4%, w/w) were exposed to UV irradiation for 25 h. The results indicated that the photocatalytic degradation of pyrene followed pseudo-first-order kinetics. TiO 2 accelerated the degradation of pyrene generally as indicated by the half-life reduction from 45.90 to 31.36 h, corresponding to the TiO 2 amounts from 0% to 4%, respectively. The effects of H 2 O 2 , light intensity and humic acids on the degradation of pyrene were also investigated. The degradation of pyrene increased along with increasing the concentration of H 2 O 2 , light intensity and the concentration of humic acids. All results indicated that the photocatalytic method in the presence of nanometer anatase TiO 2 was an advisable choice for the treatments of PAHs polluted soil in the future.

Automated Motion Correction for In Vivo Optical Projection Tomography

IEEE Transactions on Medical Imaging, 2012

In in vivo optical projection tomography (OPT), object motion will significantly reduce the quali... more In in vivo optical projection tomography (OPT), object motion will significantly reduce the quality and resolution of the reconstructed image. Based on the well-known Helgason-Ludwig consistency condition (HLCC), we propose a novel method for motion correction in OPT under parallel beam illumination. The method estimates object motion from projection data directly and does not require any other additional information, which results in a straightforward implementation. We decompose object movement into translation and rotation, and discuss how to correct for both translation and general motion simultaneously. Since finding the center of rotation accurately is critical in OPT, we also point out that the system's geometrical offset can be considered as object translation and therefore also calibrated through the translation estimation method. In order to verify the algorithm effectiveness, both simulated and in vivo OPT experiments are performed. Our results demonstrate that the proposed approach is capable of decreasing movement artifacts significantly thus providing high quality reconstructed images in the presence of object motion.

Fast Katsevich Algorithm Based on GPU for Helical Cone-Beam Computed Tomography

IEEE Transactions on Information Technology in Biomedicine, 2010

Katsevich reconstruction algorithm represents a breakthrough for helical cone-beam computed tomog... more Katsevich reconstruction algorithm represents a breakthrough for helical cone-beam computed tomography (CT) reconstruction, because it is the first exact cone-beam reconstruction algorithm of filtered backprojection (FBP) type with 1-D shiftinvariant filtering. Although FBP-type reconstruction algorithm is effective, 3-D CT reconstruction is time-consuming, and the accelerations of Katsevich algorithm on CPU or cluster have been widely studied. In this paper, Katsevich algorithm is accelerated by using graphics processing unit, including flat-detector and curveddetector geometry in the case of helical orbit. An overscan formula is derived, which helps to avoid unnecessary overscan in practical CT scanning. Based on the overscan formula, a volume-blocking method in device memory is proposed. One advantage of the blocking method is that it can reconstruct large volume with high speed. Index Terms-Computed tomography (CT), graphics processing unit (GPU), Katsevich algorithm, overscan. F ELDKAMP et al. [1] first proposed a 3-D computed to- mography (CT) algorithm of filtered backprojection (FBP) type, which is popular even now because of its efficiency. But it is an approximate algorithm, and it introduces image artifacts that will be aggravated with the increase of cone-beam angle. In 1993, a generalized Feldkamp algorithm was proposed by Wang et al. in the case of helical cone-beam CT, and it is also an approximate algorithm. In recent years, several exact algorithms have been developed, including Katsevich Manuscript

Real-Time Visualized Freehand 3D Ultrasound Reconstruction Based on GPU

IEEE Transactions on Information Technology in Biomedicine, 2010

Visualized freehand 3D ultrasound reconstruction offers to image incremental reconstruction durin... more Visualized freehand 3D ultrasound reconstruction offers to image incremental reconstruction during acquisition and guide users to scan interactively for high quality volumes. We originally used the Graphics Processing Unit (GPU) to develop a visualized reconstruction algorithm that achieves real-time level. Each newly acquired image was transferred to the memory of the GPU and inserted into the reconstruction volume on the GPU. The partially reconstructed volume was then rendered using GPU based incremental ray-casting. After visualized reconstruction, hole-filling was performed on the GPU to fill remaining empty voxels in the reconstruction volume. We examine the real-time nature of the algorithm using in vitro and in vivo data sets. The algorithm can image incremental reconstruction at speed of 26∼58 frames/s and complete 3D imaging in the acquisition time for the conventional freehand 3D ultrasound.

Propagation Characteristics of Wideband Relay Channels in Urban Micro-Cell Environment

IEEE Antennas and Wireless Propagation Letters, 2010

In order to evaluate the performance of a relay system, propagation characteristics of relay chan... more In order to evaluate the performance of a relay system, propagation characteristics of relay channels are necessary, especially in urban micro-cell (UMi) environment. We conducted wideband relay channel measurements at 2.35 GHz in two UMi sites in China by employing a real-time channel sounder. Three types of links-base station to mobile station (BS-MS), relay station to mobile station (RS-MS), and base station to relay station (BS-RS)-were measured separately at three sites. Statistical propagation characteristics are presented and compared in this letter, including path loss (PL), root mean square (rms) delay spread (DS), and angular spread (AS). These results are informative for the technical research and evaluation of the relay system. Index Terms-Angular spread (AS), delay spread (DS), multipleinput-multiple-output (MIMO), path loss (PL), relay, wideband channel measurement.