WorldWideScience
 
 
1

3D biopsy for tomosynthesis: simulation of prior information based reconstruction for dose and artifact reduction  

Science.gov (United States)

Accurately targeting of small lesions for success is crucial in breast biopsy. In this paper, we proposed a new 3D tomobased biopsy, which is characterized in being more accurate, easier to perform, lower in dose, and free of metal artifact. In the scout phase, a conventional tomosynthesis scan is performed, and the reconstructed 3D image is then used for radiologists to accurately localize target volume and determine optimized needle path. In the prefire phase, two prefire stereotactic images are obtained at +24° and -24° angular levels for retrieving needle and shifted lesion locations. By combining the reconstructed 3D tomosynthesis image, needle location and lesion location, synthetic prefire and postfire images are generated for radiologists' reference before firing the real needle. The proposed scheme not only improves the biopsy accuracy but also reduces dose by 3.7-5.6 times compared to conventional mammo-based stereotactic biopsy. A simulation using anthropomorphic phantom was conducted to verify our method. Both needle and lesion were precisely recovered just based on two tomo angled images. For the needle registration, the sum of translation discrepancy is less than 3 pixels, and the sum of rotation discrepancy is less than 3 degrees. For the lesion registration, the sum of coordinate discrepancy is less than 4 pixels. The predicted 3D prefire and postfire images exhibited more intuitive spatial relationship of the shifted lesion and biopsy needle tip than mammo-based stereotactic biopsy.

Lin, Yuan; Ghate, Sujata; Lo, Joseph; Samei, Ehsan

2012-03-01

2

Parallelizable 3D statistical reconstruction for C-arm tomosynthesis system  

Science.gov (United States)

Clinical diagnosis and security detection tasks increasingly require 3D information which is difficult or impossible to obtain from 2D (two dimensional) radiographs. As a 3D (three dimensional) radiographic and non-destructive imaging technique, digital tomosynthesis is especially fit for cases where 3D information is required while a complete projection data is not available. Nowadays, FBP (filtered back projection) is extensively used in industry for its fast speed and simplicity. However, it is hard to deal with situations where only a limited number of projections from constrained directions are available, or the SNR (signal to noises ratio) of the projections is low. In order to deal with noise and take into account a priori information of the object, a statistical image reconstruction method is described based on the acquisition model of X-ray projections. We formulate a ML (maximum likelihood) function for this model and develop an ordered-subsets iterative algorithm to estimate the unknown attenuation of the object. Simulations show that satisfied results can be obtained after 1 to 2 iterations, and after that there is no significant improvement of the image quality. An adaptive wiener filter is also applied to the reconstructed image to remove its noise. Some approximations to speed up the reconstruction computation are also considered. Applying this method to computer generated projections of a revised Shepp phantom and true projections from diagnostic radiographs of a patient"s hand and mammography images yields reconstructions with impressive quality. Parallel programming is also implemented and tested. The quality of the reconstructed object is conserved, while the computation time is considerably reduced by almost the number of threads used.

Wang, Beilei; Barner, Kenneth; Lee, Denny

2005-04-01

3

Compressed-sensing (CS)-based digital breast tomosynthesis (DBT) reconstruction for low-dose, accurate 3D breast X-ray imaging  

Science.gov (United States)

In practical applications of three-dimensional (3D) tomographic techniques, such as digital breast tomosynthesis (DBT), computed tomography (CT), etc., there are often challenges for accurate image reconstruction from incomplete data. In DBT, in particular, the limited-angle and few-view projection data are theoretically insufficient for exact reconstruction; thus, the use of common filtered-backprojection (FBP) algorithms leads to severe image artifacts, such as the loss of the average image value and edge sharpening. One possible approach to alleviate these artifacts may employ iterative statistical methods because they potentially yield reconstructed images that are in better accordance with the measured projection data. In this work, as another promising approach, we investigated potential applications to low-dose, accurate DBT imaging with a state-of-the-art reconstruction scheme based on compressed-sensing (CS) theory. We implemented an efficient CS-based DBT algorithm and performed systematic simulation works to investigate the imaging characteristics. We successfully obtained DBT images of substantially very high accuracy by using the algorithm and expect it to be applicable to developing the next-generation 3D breast X-ray imaging system.

Park, Yeonok; Cho, Hyosung; Je, Uikyu; Hong, Daeki; Lee, Minsik; Park, Chulkyu; Cho, Heemoon; Choi, Sungil; Koo, Yangseo

2014-08-01

4

An object-oriented simulator for 3D digital breast tomosynthesis imaging system.  

Science.gov (United States)

Digital breast tomosynthesis (DBT) is an innovative imaging modality that provides 3D reconstructed images of breast to detect the breast cancer. Projections obtained with an X-ray source moving in a limited angle interval are used to reconstruct 3D image of breast. Several reconstruction algorithms are available for DBT imaging. Filtered back projection algorithm has traditionally been used to reconstruct images from projections. Iterative reconstruction algorithms such as algebraic reconstruction technique (ART) were later developed. Recently, compressed sensing based methods have been proposed in tomosynthesis imaging problem. We have developed an object-oriented simulator for 3D digital breast tomosynthesis (DBT) imaging system using C++ programming language. The simulator is capable of implementing different iterative and compressed sensing based reconstruction methods on 3D digital tomosynthesis data sets and phantom models. A user friendly graphical user interface (GUI) helps users to select and run the desired methods on the designed phantom models or real data sets. The simulator has been tested on a phantom study that simulates breast tomosynthesis imaging problem. Results obtained with various methods including algebraic reconstruction technique (ART) and total variation regularized reconstruction techniques (ART+TV) are presented. Reconstruction results of the methods are compared both visually and quantitatively by evaluating performances of the methods using mean structural similarity (MSSIM) values. PMID:24371468

Seyyedi, Saeed; Cengiz, Kubra; Kamasak, Mustafa; Yildirim, Isa

2013-01-01

5

Inter-plane artifact suppression in tomosynthesis using 3D CT image data  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Despite its superb lateral resolution, flat-panel-detector (FPD based tomosynthesis suffers from low contrast and inter-plane artifacts caused by incomplete cancellation of the projection components stemming from outside the focal plane. The incomplete cancellation of the projection components, mostly due to the limited scan angle in the conventional tomosynthesis scan geometry, often makes the image contrast too low to differentiate the malignant tissues from the background tissues with confidence. Methods In this paper, we propose a new method to suppress the inter-plane artifacts in FPD-based tomosynthesis. If 3D whole volume CT images are available before the tomosynthesis scan, the CT image data can be incorporated into the tomosynthesis image reconstruction to suppress the inter-plane artifacts, hence, improving the image contrast. In the proposed technique, the projection components stemming from outside the region-of-interest (ROI are subtracted from the measured tomosynthesis projection data to suppress the inter-plane artifacts. The projection components stemming from outside the ROI are calculated from the 3D whole volume CT images which usually have lower lateral resolution than the tomosynthesis images. The tomosynthesis images are reconstructed from the subtracted projection data which account for the x-ray attenuation through the ROI. After verifying the proposed method by simulation, we have performed both CT scan and tomosynthesis scan on a phantom and a sacrificed rat using a FPD-based micro-CT. Results We have measured contrast-to-noise ratio (CNR from the tomosynthesis images which is an indicator of the residual inter-plane artifacts on the focal-plane image. In both cases of the simulation and experimental imaging studies of the contrast evaluating phantom, CNRs have been significantly improved by the proposed method. In the rat imaging also, we have observed better visual contrast from the tomosynthesis images reconstructed by the proposed method. Conclusions The proposed tomosynthesis technique can improve image contrast with aids of 3D whole volume CT images. Even though local tomosynthesis needs extra 3D CT scanning, it may find clinical applications in special situations in which extra 3D CT scan is already available or allowed.

Kim Jae G

2011-12-01

6

3D lesion insertion in digital breast tomosynthesis images  

Science.gov (United States)

Digital breast tomosynthesis (DBT) is a new volumetric breast cancer screening modality. It is based on the principles of computed tomography (CT) and shows promise for improving sensitivity and specificity compared to digital mammography, which is the current standard protocol. A barrier to critically evaluating any new modality, including DBT, is the lack of patient data from which statistically significant conclusions can be drawn; such studies require large numbers of images from both diseased and healthy patients. Since the number of detected lesions is low in relation to the entire breast cancer screening population, there is a particular need to acquire or otherwise create diseased patient data. To meet this challenge, we propose a method to insert 3D lesions in the DBT images of healthy patients, such that the resulting images appear qualitatively faithful to the modality and could be used in future clinical trials or virtual clinical trials (VCTs). The method facilitates direct control of lesion placement and lesion-to-background contrast and is agnostic to the DBT reconstruction algorithm employed.

Vaz, Michael S.; Besnehard, Quentin; Marchessoux, Cédric

2011-03-01

7

The simulation of 3D microcalcification clusters in 2D digital mammography and breast tomosynthesis  

International Nuclear Information System (INIS)

''Poor'' agreement would reflect radiologists' confusion between simulated and real clusters, i.e., lesions not systematically evaluated in both modalities as either simulated or real, and would therefore be interpreted as a success of the present models. Results: The area under the ROC curve, averaged over the observers, was 0.55 (95% confidence interval [0.44, 0.66]) for the 2D study, and 0.46 (95% confidence interval [0.29, 0.64]) for the tomosynthesis study, indicating no statistically significant difference between real and simulated lesions (p > 0.05). Agreement between allocated lesion scores for 2D mammography and those for the tomosynthesis series was poor. Conclusions: The realistic appearance of the 3D models of microcalcification clusters, whether malignant or benign clusters, was confirmed for 2D digital mammography images and the breast tomosynthesis datasets; this database of clusters is suitable for use in future observer performance studies related to the detectability of microcalcification clusters. Such studies include comparing 2D digital mammography to breast tomosynthesis and comparing different reconstruction algorithms.

8

Filter calculation for x-ray tomosynthesis reconstruction  

International Nuclear Information System (INIS)

Filtered backprojection reconstruction is an efficient image reconstruction method which is widely used in CT and 3D x-ray imaging. The way data have to be filtered depends on the acquisition geometry and the number of projections (views) which were acquired. For standard geometries like circle or helix it is known how to effectively filter the data. But there are acquisition geometries for which the application of standard filters yields poor results, e.g. in situations where the number of views is very small or for a limited angular range. In tomosynthesis, both conditions apply, i.e. the number of projections is typically very small and, moreover, the angular coverage is much less than 180°. This paper proposes a new method to design effective filters which are specific for the acquisition geometry. Examples from x-ray tomosynthesis are utilized to demonstrate the excellent performance of the proposed method. (paper)

9

Filter calculation for x-ray tomosynthesis reconstruction  

Science.gov (United States)

Filtered backprojection reconstruction is an efficient image reconstruction method which is widely used in CT and 3D x-ray imaging. The way data have to be filtered depends on the acquisition geometry and the number of projections (views) which were acquired. For standard geometries like circle or helix it is known how to effectively filter the data. But there are acquisition geometries for which the application of standard filters yields poor results, e.g. in situations where the number of views is very small or for a limited angular range. In tomosynthesis, both conditions apply, i.e. the number of projections is typically very small and, moreover, the angular coverage is much less than 180°. This paper proposes a new method to design effective filters which are specific for the acquisition geometry. Examples from x-ray tomosynthesis are utilized to demonstrate the excellent performance of the proposed method.

Nielsen, Tim; Hitziger, Sebastian; Grass, Michael; Iske, Armin

2012-06-01

10

Application of boundary detection information in breast tomosynthesis reconstruction  

International Nuclear Information System (INIS)

Digital tomosynthesis mammography (DTM) is one of the most promising techniques that can potentially improve early detection of breast cancers. DTM can provide three-dimensional (3D) structural information by reconstructing the whole imaged volume from a sequence of projection-view (PV) mammograms that are acquired at a small number of projection angles over a limited angular range. Our previous study showed that simultaneous algebraic reconstruction technique (SART) can produce satisfactory tomosynthesized image quality compared to maximum likelihood-type algorithms. To improve the efficiency of DTM reconstruction and address the problem of boundary artifacts, we have developed methods to incorporate both two-dimensional (2D) and 3D breast boundary information within the SART reconstruction algorithm in this study. A second generation GE prototype tomosynthesis mammography system with a stationary digital detector was used for PV image acquisition from 21 angles in 3 deg. increments over a ±30 deg. angular range. The 2D breast boundary curves on all PV images were obtained by automated segmentation and were used to restrict the SART reconstruction to be performed only within the breast volume. The computation time of SART reconstruction was reduced by 76.3% and 69.9% for cranio-caudal and mediolateral oblique views, respectively, for the chosen example. In addition, a 3D conical trimming method was developed in which the 2D breast boundary curves from all PVs were back projected to generate the 3D breast surface. This 3D surface was then used to eliminate the multiple breast shadows outside the breast volume due to reconstruction by setting these voxels to a constant background value. Our study demonstrates that, by using the 2D and 3D breast boundary information, all breast boundary and most detector boundary artifacts can be effectively removed on all tomosynthesized slices

11

Breast tomosynthesis reconstruction with a multi-beam x-ray source  

Science.gov (United States)

As a new three-dimensional breast imaging technique, breast tomosynthesis allows the reconstruction of an arbitrary set of planes in the breast from a limited-angle series of x-ray projection images. The breast tomosynthesis technique has been demonstrated as promising to improve early breast cancer detection. This paper represents a preliminary phantom study and computer simulation results of different breast tomosynthesis reconstruction algorithms with a novel carbon nanotube based multi-beam x-ray source. Five representative tomosynthesis reconstruction algorithms, including back projection (BP), filtered back projection (FBP), matrix inversion tomosynthesis (MITS), maximum likelihood expectation maximization (MLEM), and simultaneous algebraic reconstruction technique (SART) were investigated. Tomosynthesis projection images of a phantom were acquired with the stationary multi-beam x-ray tomosynthesis system. Reconstruction results from different algorithms were studied. A computer simulation study was further done to investigate the sharpness of reconstructed in-plane structures and to see how effective each algorithm is at removing out-of-plane blur with parallel-imaging geometries. Datasets with 9 and 25 projection images of a defined 3D spherical object were simulated with a total view angle of 50 degrees. Results showed that the multi-beam x-ray system is capable to generate 3D tomosynthesis images with faster speed compared with current commercial prototype systems. With simulated parallel-imaging geometry, MITS and FBP showed edge enhancement in-plane performance. BP, FBP and MLEM performed better at out-of-plane structure removal with larger number of projection images.

Chen, Ying; Zhou, Weihua; Yang, Guang; Qian, Xin; Lu, Jianping; Zhou, Otto

2009-02-01

12

3D statistical facial reconstruction  

CERN Document Server

The aim of craniofacial reconstruction is to produce a likeness of a face from the skull. Few works in computerized assisted facial reconstruction have been done in the past, due to poor machine performances and data availability, and major works are manually reconstructions. In this paper, we present an approach to build 3D statistical models of the skull and the face with soft tissues from the skull of one individual. Results on real data are presented and seem promising.

Berar, M; Bailly, G; Payan, Y; Berar, Maxime; Desvignes, Michel; Payan, Yohan

2005-01-01

13

Oblique reconstructions in tomosynthesis. II. Super-resolution  

International Nuclear Information System (INIS)

Purpose: In tomosynthesis, super-resolution has been demonstrated using reconstruction planes parallel to the detector. Super-resolution allows for subpixel resolution relative to the detector. The purpose of this work is to develop an analytical model that generalizes super-resolution to oblique reconstruction planes.Methods: In a digital tomosynthesis system, a sinusoidal test object is modeled along oblique angles (i.e., “pitches”) relative to the plane of the detector in a 3D divergent-beam acquisition geometry. To investigate the potential for super-resolution, the input frequency is specified to be greater than the alias frequency of the detector. Reconstructions are evaluated in an oblique plane along the extent of the object using simple backprojection (SBP) and filtered backprojection (FBP). By comparing the amplitude of the reconstruction against the attenuation coefficient of the object at various frequencies, the modulation transfer function (MTF) is calculated to determine whether modulation is within detectable limits for super-resolution. For experimental validation of super-resolution, a goniometry stand was used to orient a bar pattern phantom along various pitches relative to the breast support in a commercial digital breast tomosynthesis system.Results: Using theoretical modeling, it is shown that a single projection image cannot resolve a sine input whose frequency exceeds the detector alias frequency. The high frequency input is correctly visualized in SBP or FBP reconstruction using a slice along the pitch of the object. The Fourier transform of this reconstructed slice is maximized at the input frequency as proof that the object is resolved. Consistent with the theoretical results, experimental images of a bar pattern phantom showed super-resolution in oblique reconstructions. At various pitches, the highest frequency with detectable modulation was determined by visual inspection of the bar patterns. The dependency of the highest detectable frequency on pitch followed the same trend as the analytical model. It was demonstrated that super-resolution is not achievable if the pitch of the object approaches 90°, corresponding to the case in which the test frequency is perpendicular to the breast support. Only low frequency objects are detectable at pitches close to 90°.Conclusions: This work provides a platform for investigating super-resolution in oblique reconstructions for tomosynthesis. In breast imaging, this study should have applications in visualizing microcalcifications and other subtle signs of cancer

14

Fast reconstruction of digital tomosynthesis using on-board images  

Science.gov (United States)

Digital tomosynthesis (DTS) is a method to reconstruct pseudo three-dimensional (3D) volume images from two-dimensional x-ray projections acquired over limited scan angles. Compared with cone-beam computed tomography, which is frequently used for 3D image guided radiation therapy, DTS requires less imaging time and dose. Successful implementation of DTS for fast target localization requires the reconstruction process to be accomplished within tight clinical time constraints (usually within 2 min). To achieve this goal, substantial improvement of reconstruction efficiency is necessary. In this study, a reconstruction process based upon the algorithm proposed by Feldkamp, Davis, and Kress was implemented on graphics hardware for the purpose of acceleration. The performance of the novel reconstruction implementation was tested for phantom and real patient cases. The efficiency of DTS reconstruction was improved by a factor of 13 on average, without compromising image quality. With acceleration of the reconstruction algorithm, the whole DTS generation process including data preprocessing, reconstruction, and DICOM conversion is accomplished within 1.5 min, which ultimately meets clinical requirement for on-line target localization. PMID:18561691

Yan, Hui; Godfrey, Devon J.; Yin, Fang-Fang

2008-01-01

15

Simulation of 3D objects into breast tomo-synthesis images  

International Nuclear Information System (INIS)

Digital breast tomo-synthesis is a new three-dimensional (3D) breast-imaging modality that produces images of cross-sectional planes parallel to the detector plane from a limited number of X-ray projections over a limited angular range. Several technical and clinical parameters have not yet been completely optimised. Some of the open questions could be addressed experimentally; other parameter settings cannot be easily realised in practice and the associated optimisation process requires therefore a theoretical approach. Rather than simulating the complete 3D imaging chain, it is hypothesised that the simulation of small lesions into clinical (or test object) images can be of help in the optimisation process. In the present study, small 3D objects have been simulated into real projection images. Subsequently, these hybrid projection images are reconstructed using the routine clinical reconstruction tools. In this study, the validation of this simulation framework is reported through the comparison between simulated and real objects in reconstructed planes. The results confirm that there is no statistically significant difference between the simulated and the real objects. This suggests that other small mathematical or physiological objects could be simulated with the same approach. (authors)

16

Truncation artifact and boundary artifact reduction in breast tomosynthesis reconstruction  

Science.gov (United States)

Digital Tomosynthesis Mammography (DTM) is an emerging technique that has the potential to improve breast cancer detection. DTM acquires low-dose mammograms at a number of projection angles over a limited angular range and reconstructs the 3D breast volume. Due to the limited number of projections within a limited angular range and the finite size of the detector, DTM reconstruction contains boundary and truncation artifacts that degrade the image quality of the tomosynthesized slices, especially that of the boundary and truncated regions. In this work, we developed artifact reduction methods that make use of both 2D and 3D breast boundary information and local intensity-equalization and tissue-compensation techniques. A breast phantom containing test objects and a selected DTM patient case were used to evaluate the effects of artifact reduction. The contrast-to-noise ratio (CNR), the normalized profiles of test objects, and a non-uniformity error index were used as performance measures. A GE prototype DTM system was used to acquire 21 PVs in 3° increments over a +/-30° angular range. The Simultaneous Algebraic Reconstruction Technique (SART) was used for DTM reconstruction. Our results demonstrated that the proposed methods can improve the image quality both qualitatively and quantitatively, resulting in increased CNR value, background uniformity and an overall reconstruction quality comparable to that without truncation. For the selected DTM patient case, the obscured breast structural information near the truncated regions was essentially recovered. In addition, restricting SART reconstruction to be performed within the estimated 3D breast volume increased the computation efficiency.

Zhang, Yiheng; Chan, Heang-Ping; Wu, Yi-Ta; Sahiner, Berkman; Zhou, Chuan; Wei, Jun; Ge, Jun; Hadjiiski, Lubomir M.; Shi, Jiazheng

2008-03-01

17

Optimized image acquisition for breast tomosynthesis in projection and reconstruction space  

International Nuclear Information System (INIS)

Breast tomosynthesis has been an exciting new development in the field of breast imaging. While the diagnostic improvement via tomosynthesis is notable, the full potential of tomosynthesis has not yet been realized. This may be attributed to the dependency of the diagnostic quality of tomosynthesis on multiple variables, each of which needs to be optimized. Those include dose, number of angular projections, and the total angular span of those projections. In this study, the authors investigated the effects of these acquisition parameters on the overall diagnostic image quality of breast tomosynthesis in both the projection and reconstruction space. Five mastectomy specimens were imaged using a prototype tomosynthesis system. 25 angular projections of each specimen were acquired at 6.2 times typical single-view clinical dose level. Images at lower dose levels were then simulated using a noise modification routine. Each projection image was supplemented with 84 simulated 3 mm 3D lesions embedded at the center of 84 nonoverlapping ROIs. The projection images were then reconstructed using a filtered backprojection algorithm at different combinations of acquisition parameters to investigate which of the many possible combinations maximizes the performance. Performance was evaluated in terms of a Laguerre-Gauss channelized Hotelling observer model-based measure of lesion detectability. The analysis was also performed without reconstruction by combining the model results froruction by combining the model results from projection images using Bayesian decision fusion algorithm. The effect of acquisition parameters on projection images and reconstructed slices were then compared to derive an optimization rule for tomosynthesis. The results indicated that projection images yield comparable but higher performance than reconstructed images. Both modes, however, offered similar trends: Performance improved with an increase in the total acquisition dose level and the angular span. Using a constant dose level and angular span, the performance rolled off beyond a certain number of projections, indicating that simply increasing the number of projections in tomosynthesis may not necessarily improve its performance. The best performance for both projection images and tomosynthesis slices was obtained for 15-17 projections spanning an angular arc of ?45 deg. - the maximum tested in our study, and for an acquisition dose equal to single-view mammography. The optimization framework developed in this framework is applicable to other reconstruction techniques and other multiprojection systems.

18

Optimized image acquisition for breast tomosynthesis in projection and reconstruction space  

Energy Technology Data Exchange (ETDEWEB)

Breast tomosynthesis has been an exciting new development in the field of breast imaging. While the diagnostic improvement via tomosynthesis is notable, the full potential of tomosynthesis has not yet been realized. This may be attributed to the dependency of the diagnostic quality of tomosynthesis on multiple variables, each of which needs to be optimized. Those include dose, number of angular projections, and the total angular span of those projections. In this study, the authors investigated the effects of these acquisition parameters on the overall diagnostic image quality of breast tomosynthesis in both the projection and reconstruction space. Five mastectomy specimens were imaged using a prototype tomosynthesis system. 25 angular projections of each specimen were acquired at 6.2 times typical single-view clinical dose level. Images at lower dose levels were then simulated using a noise modification routine. Each projection image was supplemented with 84 simulated 3 mm 3D lesions embedded at the center of 84 nonoverlapping ROIs. The projection images were then reconstructed using a filtered backprojection algorithm at different combinations of acquisition parameters to investigate which of the many possible combinations maximizes the performance. Performance was evaluated in terms of a Laguerre-Gauss channelized Hotelling observer model-based measure of lesion detectability. The analysis was also performed without reconstruction by combining the model results from projection images using Bayesian decision fusion algorithm. The effect of acquisition parameters on projection images and reconstructed slices were then compared to derive an optimization rule for tomosynthesis. The results indicated that projection images yield comparable but higher performance than reconstructed images. Both modes, however, offered similar trends: Performance improved with an increase in the total acquisition dose level and the angular span. Using a constant dose level and angular span, the performance rolled off beyond a certain number of projections, indicating that simply increasing the number of projections in tomosynthesis may not necessarily improve its performance. The best performance for both projection images and tomosynthesis slices was obtained for 15-17 projections spanning an angular arc of {approx}45 deg. - the maximum tested in our study, and for an acquisition dose equal to single-view mammography. The optimization framework developed in this framework is applicable to other reconstruction techniques and other multiprojection systems.

Chawla, Amarpreet S.; Lo, Joseph Y.; Baker, Jay A.; Samei, Ehsan [Department of Radiology and Department of Biomedical Engineering, Duke Advanced Imaging Laboratories, Duke University, Durham, North Carolina 27705 (United States); Department of Radiology, Department of Medical Physics, and Department of Biomedical Engineering, Duke Advanced Imaging Laboratories, Duke University Durham, North Carolina 27705 (United States); Department of Radiology, Duke Advanced Imaging Laboratories, Duke University Durham, North Carolina 27705 (United States); Department of Radiology, Department of Medical Physics, and Department of Biomedical Engineering, Duke Advanced Imaging Laboratories, Duke University Durham, North Carolina 27705 (United States)

2009-11-15

19

Digital breast tomosynthesis reconstruction with an adaptive voxel grid  

Science.gov (United States)

In digital breast tomosynthesis (DBT) volume datasets are typically reconstructed with an anisotropic voxel size, where the in-plane voxel size usually reflects the detector pixel size (e.g., 0.1 mm), and the slice separation is generally between 0.5-1.0 mm. Increasing the tomographic angle is expected to give better 3D image quality; however, the slice spacing in the reconstruction should be reduced, otherwise one may risk losing fine-scale image detail (e.g., small microcalcifications). An alternative strategy consists of reconstructing on an adaptive voxel grid, where the voxel height at each location is adapted based on the backprojected data at this location, with the goal to improve image quality for microcalcifications. In this paper we present an approach for generating such an adaptive voxel grid. This approach is based on an initial reconstruction step that is performed at a finer slice-spacing combined with a selection of an "optimal" height for each voxel. This initial step is followed by a (potentially iterative) reconstruction acting now on the adaptive grid only.

Claus, Bernhard; Chan, Heang-Ping

2014-03-01

20

A novel approach to digital breast tomosynthesis for simultaneous acquisition of 2D and 3D images  

Energy Technology Data Exchange (ETDEWEB)

The complexity of anatomical structure within the breast represents the ultimate limit to signal detection on a mammogram. To increase lesion conspicuity Digital Breast Tomosynthesis (DBT) has been recently proposed and several manufacturers are currently performing clinical trials. In this study we investigate the potential of DBT with variable dose distribution by using a phantom in which details of interest are within a heterogeneous background. To compare the performance of a commercial digital mammography unit and a DBT prototype, 2D and 3D images of the breast phantom were obtained at similar dose levels. As expected, DBT showed superior performance over digital mammography. Although certain details of interest are not detectable with digital mammography, DBT can reveal their signal by reducing the complexity of tissue structures. Additionally, the potential of the central projection in variable dose DBT is similar to the standard projection obtained with digital mammography. Finally, the uniform and variable dose approaches provided almost identical reconstructed slices. This preliminary investigation demonstrates that breast tomosynthesis acquired with variable dose distribution exhibits inherent 3D reconstruction advantages for structure noise removal and provides a 2D projection with a physical image quality close to that of standard mammography. (orig.)

Vecchio, Sara [University of Bologna, Department of Physics, Bologna (Italy); Albanese, Achille; Vignoli, Paolo [Internazionale Medico Scientifica S.r.l., Pontecchio Marconi, BO (Italy); Taibi, Angelo [University of Ferrara, Department of Physics, Ferrara (Italy)

2011-06-15

 
 
 
 
21

A novel approach to digital breast tomosynthesis for simultaneous acquisition of 2D and 3D images  

International Nuclear Information System (INIS)

The complexity of anatomical structure within the breast represents the ultimate limit to signal detection on a mammogram. To increase lesion conspicuity Digital Breast Tomosynthesis (DBT) has been recently proposed and several manufacturers are currently performing clinical trials. In this study we investigate the potential of DBT with variable dose distribution by using a phantom in which details of interest are within a heterogeneous background. To compare the performance of a commercial digital mammography unit and a DBT prototype, 2D and 3D images of the breast phantom were obtained at similar dose levels. As expected, DBT showed superior performance over digital mammography. Although certain details of interest are not detectable with digital mammography, DBT can reveal their signal by reducing the complexity of tissue structures. Additionally, the potential of the central projection in variable dose DBT is similar to the standard projection obtained with digital mammography. Finally, the uniform and variable dose approaches provided almost identical reconstructed slices. This preliminary investigation demonstrates that breast tomosynthesis acquired with variable dose distribution exhibits inherent 3D reconstruction advantages for structure noise removal and provides a 2D projection with a physical image quality close to that of standard mammography. (orig.)

22

Forensic 3D Scene Reconstruction  

International Nuclear Information System (INIS)

Traditionally law enforcement agencies have relied on basic measurement and imaging tools, such as tape measures and cameras, in recording a crime scene. A disadvantage of these methods is that they are slow and cumbersome. The development of a portable system that can rapidly record a crime scene with current camera imaging, 3D geometric surface maps, and contribute quantitative measurements such as accurate relative positioning of crime scene objects, would be an asset to law enforcement agents in collecting and recording significant forensic data. The purpose of this project is to develop a feasible prototype of a fast, accurate, 3D measurement and imaging system that would support law enforcement agents to quickly document and accurately record a crime scene

23

Forensic 3D Scene Reconstruction  

Energy Technology Data Exchange (ETDEWEB)

Traditionally law enforcement agencies have relied on basic measurement and imaging tools, such as tape measures and cameras, in recording a crime scene. A disadvantage of these methods is that they are slow and cumbersome. The development of a portable system that can rapidly record a crime scene with current camera imaging, 3D geometric surface maps, and contribute quantitative measurements such as accurate relative positioning of crime scene objects, would be an asset to law enforcement agents in collecting and recording significant forensic data. The purpose of this project is to develop a feasible prototype of a fast, accurate, 3D measurement and imaging system that would support law enforcement agents to quickly document and accurately record a crime scene.

LITTLE,CHARLES Q.; PETERS,RALPH R.; RIGDON,J. BRIAN; SMALL,DANIEL E.

1999-10-12

24

A task-based comparison of two reconstruction algorithms for digital breast tomosynthesis  

Science.gov (United States)

Digital breast tomosynthesis (DBT) generates 3-D reconstructions of the breast by taking X-Ray projections at various angles around the breast. DBT improves cancer detection as it minimizes tissue overlap that is present in traditional 2-D mammography. In this work, two methods of reconstruction, filtered backprojection (FBP) and the Newton-Raphson iterative reconstruction were used to create 3-D reconstructions from phantom images acquired on a breast tomosynthesis system. The task based image analysis method was used to compare the performance of each reconstruction technique. The task simulated a 10mm lesion within the breast containing iodine concentrations between 0.0mg/ml and 8.6mg/ml. The TTF was calculated using the reconstruction of an edge phantom, and the NPS was measured with a structured breast phantom (CIRS 020) over different exposure levels. The detectability index d' was calculated to assess image quality of the reconstructed phantom images. Image quality was assessed for both conventional, single energy and dual energy subtracted reconstructions. Dose allocation between the high and low energy scans was also examined. Over the full range of dose allocations, the iterative reconstruction yielded a higher detectability index than the FBP for single energy reconstructions. For dual energy subtraction, detectability index was maximized when most of the dose was allocated to the high energy image. With that dose allocation, the performance trend for reconstruction algorithms reversed; FBP performed better than the corresponding iterative reconstruction. However, FBP performance varied very erratically with changing dose allocation. Therefore, iterative reconstruction is preferred for both imaging modalities despite underperforming dual energy FBP, as it provides stable results.

Mahadevan, Ravi; Ikejimba, Lynda C.; Lin, Yuan; Samei, Ehsan; Lo, Joseph Y.

2014-03-01

25

Comparison of reconstruction algorithms for digital breast tomosynthesis  

CERN Document Server

Digital breast tomosynthesis (DBT) is an emerging modality for breast imaging. A typical tomosynthesis image is reconstructed from projection data acquired at a limited number of views over a limited angular range. In general, the quantitative accuracy of the image can be significantly compromised by severe artifacts and non-isotropic resolution resulting from the incomplete data. Nevertheless, it has been demonstrated that DBT may yield useful information for detection/classification tasks and thus is considered a promising breast imaging modality currently undergoing pre-clinical evaluation trials. The purpose of this work is to conduct a preliminary, but systematic, investigation and evaluation of the properties of reconstruction algorithms that have been proposed for DBT. We use a breast phantom designed for DBT evaluation to generate analytic projection data for a typical DBT configuration, which is currently undergoing pre-clinical evaluation. The reconstruction algorithms under comparison include (i) f...

Reiser, I; Nishikawa, R M; Sidky, E Y; Pan, X

2009-01-01

26

Development of model observers applied to 3D breast tomosynthesis microcalcifications and masses  

Science.gov (United States)

The development of model observers for mimicking human detection strategies has followed from symmetric signals in simple noise to increasingly complex backgrounds. In this study we implement different model observers for the complex task of detecting a signal in a 3D image stack. The backgrounds come from real breast tomosynthesis acquisitions and the signals were simulated and reconstructed within the volume. Two different tasks relevant to the early detection of breast cancer were considered: detecting an 8 mm mass and detecting a cluster of microcalcifications. The model observers were calculated using a channelized Hotelling observer (CHO) with dense difference-of-Gaussian channels, and a modified (Partial prewhitening [PPW]) observer which was adapted to realistic signals which are not circularly symmetric. The sustained temporal sensitivity function was used to filter the images before applying the spatial templates. For a frame rate of five frames per second, the only CHO that we calculated performed worse than the humans in a 4-AFC experiment. The other observers were variations of PPW and outperformed human observers in every single case. This initial frame rate was a rather low speed and the temporal filtering did not affect the results compared to a data set with no human temporal effects taken into account. We subsequently investigated two higher speeds at 5, 15 and 30 frames per second. We observed that for large masses, the two types of model observers investigated outperformed the human observers and would be suitable with the appropriate addition of internal noise. However, for microcalcifications both only the PPW observer consistently outperformed the humans. The study demonstrated the possibility of using a model observer which takes into account the temporal effects of scrolling through an image stack while being able to effectively detect a range of mass sizes and distributions.

Diaz, Ivan; Timberg, Pontus; Zhang, Sheng; Abbey, Craig; Verdun, Francis; Bochud, François O.

2011-03-01

27

Computer-aided detection of clustered microcalcifications in digital breast tomosynthesis: A 3D approach  

Science.gov (United States)

Purpose: To design a computer-aided detection (CADe) system for clustered microcalcifications in reconstructed digital breast tomosynthesis (DBT) volumes and to perform a preliminary evaluation of the CADe system. Methods: IRB approval and informed consent were obtained in this study. A data set of two-view DBT of 72 breasts containing microcalcification clusters was collected from 72 subjects who were scheduled to undergo breast biopsy. Based on tissue sampling results, 17 cases had breast cancer and 55 were benign. A separate data set of two-view DBT of 38 breasts free of clustered microcalcifications from 38 subjects was collected to independently estimate the number of false-positives (FPs) generated by the CADe system. A radiologist experienced in breast imaging marked the biopsied cluster of microcalcifications with a 3D bounding box using all available clinical and imaging information. A CADe system was designed to detect microcalcification clusters in the reconstructed volume. The system consisted of prescreening, clustering, and false-positive reduction stages. In the prescreening stage, the conspicuity of microcalcification-like objects was increased by an enhancement-modulated 3D calcification response function. An iterative thresholding and 3D object growing method was used to detect cluster seed objects, which were used as potential centers of microcalcification clusters. In the cluster detection stage, microcalcification candidates were identified using a second iterative thresholding procedure, which was applied to the signal-to-noise ratio (SNR) enhanced image voxels with a positive calcification response. Starting with each cluster seed object as the initial cluster center, a dynamic clustering algorithm formed a cluster candidate by including microcalcification candidates within a 3D neighborhood of the cluster seed object that satisfied the clustering criteria. The number, size, and SNR of the microcalcifications in a cluster candidate and the cluster shape were used to reduce the number of FPs. Results: The prescreening stage detected a cluster seed object in 94% of the biopsied microcalcification clusters at a threshold of 100 cluster seed objects per DBT volume. After clustering, the detection sensitivity was 90% at 15 marks per DBT volume. After FP reduction, at 85% sensitivity, the average number of FPs estimated using the data set containing microcalcification clusters was 3.8 per DBT volume, and that estimated using the data set free of microcalcification clusters was 3.4. The detection performance for malignant microcalcification clusters was superior to that for benign clusters. Conclusions: Our study indicates the feasibility of the 3D approach to the detection of clustered microcalcifications in DBT and that the newly designed enhancement-modulated 3D calcification response function is promising for prescreening. Further work is needed to assess the generalizability of our approach and to improve its performance. PMID:22225272

Sahiner, Berkman; Chan, Heang-Ping; Hadjiiski, Lubomir M.; Helvie, Mark A.; Wei, Jun; Zhou, Chuan; Lu, Yao

2012-01-01

28

3-D image reconstruction in radiology  

International Nuclear Information System (INIS)

In this course, we present highlights on fully 3-D image reconstruction algorithms used in 3-D X-ray Computed Tomography (3-D-CT) and 3-D Rotational Radiography (3-D-RR). We first consider the case of spiral CT with a one-row detector. Starting from the 2-D fan-beam inversion formula for a circular trajectory, we introduce spiral CT 3-D image reconstruction algorithm using axial interpolation for each transverse slice. In order to improve the X-ray detection efficiency and to speed the acquisition process, the future is to use multi-row detectors associated with small angle cone-beam geometry. The generalization of the 2-D fan-beam image reconstruction algorithm to cone beam defined direct inversion formula referred as Feldkamp's algorithm for a circular trajectory and Wang's algorithm for a spiral trajectory. However, large area detectors does exist such as Radiological Image Intensifiers or in a near future solid state detectors. To get a larger zoom effect, it defines a cone-beam geometry associated with a large aperture angle. For this case, we introduce indirect image reconstruction algorithm by plane re-binning in the Radon domain. We will present some results from a prototype MORPHOMETER device using the RADON reconstruction software. Lastly, we consider the special case of 3-D Rotational Digital Subtraction Angiography with a restricted number of views. We introduce constraint optimization algorithm using quadratic, entropic or half-quadratic constraints. Generalized ART (Algebraic Reconstruction Technique) iterative reconstruction algorithm can be derived from the Bregman algorithm. We present reconstructed vascular trees from a prototype MORPHOMETER device. (author)

29

Multiview 3D reconstruction in geosciences  

Science.gov (United States)

Multiview three-dimensional (3D) reconstruction is a technology that allows the creation of 3D models of a given scenario from a series of overlapping pictures taken using consumer-grade digital cameras. This type of 3D reconstruction is facilitated by freely available software, which does not require expert-level skills. This technology provides a 3D working environment, which integrates sample/field data visualization and measurement tools. In this study, we test the potential of this method for 3D reconstruction of decimeter-scale objects of geological interest. We generated 3D models of three different outcrops exposed in a marble quarry and two solids: a volcanic bomb and a stalagmite. Comparison of the models obtained in this study using the presented method with those obtained using a precise laser scanner shows that multiview 3D reconstruction yields models that present a root mean square error/average linear dimensions between 0.11 and 0.68%. Thus this technology turns out to be an extremely promising tool, which can be fruitfully applied in geosciences.

Favalli, M.; Fornaciai, A.; Isola, I.; Tarquini, S.; Nannipieri, L.

2012-07-01

30

Numerical Methods for Coupled Reconstruction and Registration in Digital Breast Tomosynthesis  

CERN Document Server

Digital Breast Tomosynthesis (DBT) provides an insight into the fine details of normal fibroglandular tissues and abnormal lesions by reconstructing a pseudo-3D image of the breast. In this respect, DBT overcomes a major limitation of conventional X-ray mammography by reducing the confounding effects caused by the superposition of breast tissue. In a breast cancer screening or diagnostic context, a radiologist is interested in detecting change, which might be indicative of malignant disease. To help automate this task image registration is required to establish spatial correspondence between time points. Typically, images, such as MRI or CT, are first reconstructed and then registered. This approach can be effective if reconstructing using a complete set of data. However, for ill-posed, limited-angle problems such as DBT, estimating the deformation is complicated by the significant artefacts associated with the reconstruction, leading to severe inaccuracies in the registration. This paper presents a mathemati...

Yang, Guang; Hawkes, David J; Arridge, Simon R

2013-01-01

31

The development of an 'on-belt tomosynthesis' system for cost-effective (3D) baggage screening  

Science.gov (United States)

This study describes a cost-effective check-in baggage screening system, based on `on-belt tomosynthesis' (ObT) and close-range photogrammetry, which is designed to address the limitations of the most common method of baggage screening, conventional projection radiography. The latter's limitations can lead to loss of information and an increase in baggage handling time, as baggage is manually searched or screened with more advanced systems. This project proposes a system that overcomes such limitations creating a cost-effective automated pseudo-3D imaging system, by combining x-ray and optical imaging to form digital tomograms. Tomosynthesis is the creation of pseudo-3D images from a number of 2D projections which are acquired at a range of orientations around a static object. In the ObT system, instead of moving the source and detectors around the object, as in conventional CT, the movement of bags around bends in the baggage transport system provides the required relative motion between source, object and a fan configuration of stripdetectors. For image reconstruction it is necessary to accurately establish the sequential position and orientation of each bag as it is imaged. For this, a low-cost photogrammetric solution is used, based on geometrically calibrated web- cameras positioned around the bends where the bags are imaged. This paper describes a study demonstrating the feasibility of implementing close-range photogrammetry to a potential ObT system, for accurate determination of the object location. After this, an optimum ObT system is designed and built, the process of which is presented in this paper.

Kolokytha, S.; Speller, Robert; Robson, Stuart

2013-06-01

32

Comparison of power spectra for tomosynthesis projections and reconstructed images  

International Nuclear Information System (INIS)

Burgess et al. [Med. Phys. 28, 419-437 (2001)] showed that the power spectrum of mammographic breast background follows a power law and that lesion detectability is affected by the power-law exponent ? which measures the amount of structure in the background. Following the study of Burgess et al., the authors measured and compared the power-law exponent of mammographic backgrounds in tomosynthesis projections and reconstructed slices to investigate the effect of tomosynthesis imaging on background structure. Our data set consisted of 55 patient cases. For each case, regions of interest (ROIs) were extracted from both projection images and reconstructed slices. The periodogram of each ROI was computed by taking the squared modulus of the Fourier transform of the ROI. The power-law exponent was determined for each periodogram and averaged across all ROIs extracted from all projections or reconstructed slices for each patient data set. For the projections, the mean ? averaged across the 55 cases was 3.06 (standard deviation of 0.21), while it was 2.87 (0.24) for the corresponding reconstructions. The difference in ? for a given patient between the projection ROIs and the reconstructed ROIs averaged across the 55 cases was 0.194, which was statistically significant (p<0.001). The 95% CI for the difference between the mean value of ? for the projections and reconstructions was [0.170, 0.218]. The results are consistent with the observation that the amount of breast structure in the tomosynthesis slice is reduced compared to projection mammography and that this may lead to improved lesion detectability.

33

The development of a pseudo-3D imaging system (tomosynthesis) for security screening of passenger baggage  

International Nuclear Information System (INIS)

This paper describes a study investigating the potential of tomosynthesis as a post check-in baggage scanning system. A laboratory system has been constructed consisting of a moveable source and detector, arranged around a mini 90o bend conveyor system, from which multiple projection images can be collected. Simulation code has been developed to allow the optimum source and detector positions to be determined. Reconstruction methods are being developed to modify the Shift-And-Add (SAA) algorithm to accommodate the non-typical imaging geometry.

34

Reproducibility of 3D chromatin configuration reconstructions.  

Science.gov (United States)

It is widely recognized that the three-dimensional (3D) architecture of eukaryotic chromatin plays an important role in processes such as gene regulation and cancer-driving gene fusions. Observing or inferring this 3D structure at even modest resolutions had been problematic, since genomes are highly condensed and traditional assays are coarse. However, recently devised high-throughput molecular techniques have changed this situation. Notably, the development of a suite of chromatin conformation capture (CCC) assays has enabled elicitation of contacts-spatially close chromosomal loci-which have provided insights into chromatin architecture. Most analysis of CCC data has focused on the contact level, with less effort directed toward obtaining 3D reconstructions and evaluating the accuracy and reproducibility thereof. While questions of accuracy must be addressed experimentally, questions of reproducibility can be addressed statistically-the purpose of this paper. We use a constrained optimization technique to reconstruct chromatin configurations for a number of closely related yeast datasets and assess reproducibility using four metrics that measure the distance between 3D configurations. The first of these, Procrustes fitting, measures configuration closeness after applying reflection, rotation, translation, and scaling-based alignment of the structures. The others base comparisons on the within-configuration inter-point distance matrix. Inferential results for these metrics rely on suitable permutation approaches. Results indicate that distance matrix-based approaches are preferable to Procrustes analysis, not because of the metrics per se but rather on account of the ability to customize permutation schemes to handle within-chromosome contiguity. It has recently been emphasized that the use of constrained optimization approaches to 3D architecture reconstruction are prone to being trapped in local minima. Our methods of reproducibility assessment provide a means for comparing 3D reconstruction solutions so that we can discern between local and global optima by contrasting solutions under perturbed inputs. PMID:24519450

Segal, Mark R; Xiong, Hao; Capurso, Daniel; Vazquez, Mariel; Arsuaga, Javier

2014-07-01

35

Convergence of iterative image reconstruction algorithms for Digital Breast Tomosynthesis  

DEFF Research Database (Denmark)

Most iterative image reconstruction algorithms are based on some form of optimization, such as minimization of a data-fidelity term plus an image regularizing penalty term. While achieving the solution of these optimization problems may not directly be clinically relevant, accurate optimization solutions can aid in iterative image reconstruction algorithm design. This issue is particularly acute for iterative image reconstruction in Digital Breast Tomosynthesis (DBT), where the corresponding data model IS particularly poorly conditioned. The impact of this poor conditioning is that iterative algorithms applied to this system can be slow to converge. Recent developments in first-order algorithms are now beginning to allow for accurate solutions to optimization problems of interest to tomographic imaging in general. In particular, we investigate an algorithm developed by Chambolle and Pock (2011 J. Math. Imag. Vol. 40, pgs 120-145) and apply it to iterative image reconstruction in DBT.

JØrgensen, Jakob Heide

2012-01-01

36

Fully 3D GPU PET reconstruction  

Energy Technology Data Exchange (ETDEWEB)

Fully 3D iterative tomographic image reconstruction is computationally very demanding. Graphics Processing Unit (GPU) has been proposed for many years as potential accelerators in complex scientific problems, but it has not been used until the recent advances in the programmability of GPUs that the best available reconstruction codes have started to be implemented to be run on GPUs. This work presents a GPU-based fully 3D PET iterative reconstruction software. This new code may reconstruct sinogram data from several commercially available PET scanners. The most important and time-consuming parts of the code, the forward and backward projection operations, are based on an accurate model of the scanner obtained with the Monte Carlo code PeneloPET and they have been massively parallelized on the GPU. For the PET scanners considered, the GPU-based code is more than 70 times faster than a similar code running on a single core of a fast CPU, obtaining in both cases the same images. The code has been designed to be easily adapted to reconstruct sinograms from any other PET scanner, including scanner prototypes.

Herraiz, J.L., E-mail: joaquin@nuclear.fis.ucm.es [Grupo de Fisica Nuclear, Departmento Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid (Spain); Espana, S. [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Cal-Gonzalez, J. [Grupo de Fisica Nuclear, Departmento Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid (Spain); Vaquero, J.J. [Departmento de Bioingenieria e Ingenieria Espacial, Universidad Carlos III, Madrid (Spain); Desco, M. [Departmento de Bioingenieria e Ingenieria Espacial, Universidad Carlos III, Madrid (Spain); Unidad de Medicina y Cirugia Experimental, Hospital General Universitario Gregorio Maranon, Madrid (Spain); Udias, J.M. [Grupo de Fisica Nuclear, Departmento Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid (Spain)

2011-08-21

37

Fully 3D GPU PET reconstruction  

International Nuclear Information System (INIS)

Fully 3D iterative tomographic image reconstruction is computationally very demanding. Graphics Processing Unit (GPU) has been proposed for many years as potential accelerators in complex scientific problems, but it has not been used until the recent advances in the programmability of GPUs that the best available reconstruction codes have started to be implemented to be run on GPUs. This work presents a GPU-based fully 3D PET iterative reconstruction software. This new code may reconstruct sinogram data from several commercially available PET scanners. The most important and time-consuming parts of the code, the forward and backward projection operations, are based on an accurate model of the scanner obtained with the Monte Carlo code PeneloPET and they have been massively parallelized on the GPU. For the PET scanners considered, the GPU-based code is more than 70 times faster than a similar code running on a single core of a fast CPU, obtaining in both cases the same images. The code has been designed to be easily adapted to reconstruct sinograms from any other PET scanner, including scanner prototypes.

38

Dose reduction in digital breast tomosynthesis using a penalized maximum likelihood reconstruction  

Science.gov (United States)

Digital breast tomosynthesis (DBT) is a 3D imaging modality with limited angle projection data. The ability of tomosynthesis systems to accurately detect smaller microcalcifications is debatable. This is because of the higher noise in the projection data (lower average dose per projection), which is then propagated through the reconstructed image . Reconstruction methods that minimize the propagation of quantum noise have potential to improve microcalcification detectability using DBT. In this paper we show that penalized maximum likelihood (PML) reconstruction in DBT yields images with an improved resolution/noise tradeoff as compared to conventional filtered backprojection (FBP). Signal to noise ratio (SNR) using PML was observed to be higher than that obtained using the standard FBP algorithm. Our results indicate that for microcalcifications, using the PML algorithm, reconstructions obtained with a mean glandular dose (MGD) of 1.5 mGy yielded better SNR than that those obtained with FBP using a 4mGy total dose. Thus perhaps total dose could be reduced to one-third or lower with same microcalcification detectability, if PML reconstruction is used instead of FBP. Visibility of low contrast masses with various contrast levels were studied using a contrast-detail phantom in a breast shape structure with an average breast density. Images generated using various dose levels indicate that visibility of low contrast masses generated using PML reconstructions are significantly better than those generated using FBP. SNR measurements in the low-contrast study did not appear to correlate with the visual subjective analysis of the reconstruction indicating that SNR is not a good figure of merit to be used.

Das, Mini; Gifford, Howard; O'Connor, Michael; Glick, Stephen J.

2009-02-01

39

Multiaperture telecentric lens for 3D reconstruction.  

Science.gov (United States)

We present a telecentric lens that is able to gain 3D information. The proposed lens system has multiple aperture stops, which enable it to capture multidirectional parallel light rays, while a conventional telecentric lens has only one aperture stop and can capture only light rays that are perpendicular to the lens. We explain the geometry of the multiaperture telecentric system and show that correspondences fall on a line like those in a conventional stereo. As it is a single-lens sensor, we also introduce the principles of 3D reconstruction. Unlike a conventional stereo camera, the disparity of a scene point measured by the proposed lens system is linearly proportional to the depth of a scene point. PMID:21478979

Kim, Jun-Sik; Kanade, Takeo

2011-04-01

40

A 3D linear system model for the optimization of dual-energy contrast-enhanced digital breast tomosynthesis  

Science.gov (United States)

Digital breast tomosynthesis (DBT) is a three-dimensional (3D) x-ray imaging modality that has been shown to decrease the obscuring effect of breast structural noise, thereby increasing lesion conspicuity. To further improve breast cancer detection, much recent work has been devoted to the development of contrast enhanced DBT (CEDBT). Taking advantage of angiogenesis in malignant tissue, CEDBT involves the injection of radio-opaque material (i.e. iodine) and measures the relative increase in uptake of contrast in breast cancer. Either temporal or dual energy subtraction techniques may be used to implement CEDBT. Our present work is to develop a cascaded linear system model for DBT with a CEDBT option to calculate the ideal observer signal to noise ratio (SNR) of lesions in the presence of structural noise, evaluate the efficacy of CEDBT in the removal of structural noise, and examine the associated increase in x-ray quantum noise. Our model will include the effects of dual energy subtraction on signal and noise transfer, and transfer of power-law form anatomical noise through a DBT system using a modified filtered backprojection (FBP) algorithm. This model will be used for the optimization of x-ray techniques and reconstruction filters in CEDBT.

Hu, Yue-Houng; Zhao, Wei

2011-03-01

 
 
 
 
41

3D reconstruction of tensors and vectors  

Energy Technology Data Exchange (ETDEWEB)

Here we have developed formulations for the reconstruction of 3D tensor fields from planar (Radon) and line-integral (X-ray) projections of 3D vector and tensor fields. Much of the motivation for this work is the potential application of MRI to perform diffusion tensor tomography. The goal is to develop a theory for the reconstruction of both Radon planar and X-ray or line-integral projections because of the flexibility of MRI to obtain both of these type of projections in 3D. The development presented here for the linear tensor tomography problem provides insight into the structure of the nonlinear MRI diffusion tensor inverse problem. A particular application of tensor imaging in MRI is the potential application of cardiac diffusion tensor tomography for determining in vivo cardiac fiber structure. One difficulty in the cardiac application is the motion of the heart. This presents a need for developing future theory for tensor tomography in a motion field. This means developing a better understanding of the MRI signal for diffusion processes in a deforming media. The techniques developed may allow the application of MRI tensor tomography for the study of structure of fiber tracts in the brain, atherosclerotic plaque, and spine in addition to fiber structure in the heart. However, the relations presented are also applicable to other fields in medical imaging such as diffraction tomography using ultrasound. The mathematics presented can also be extended to exponential Radon transform of tensor fields and to other geometric acquisitions such as cone beam tomography of tensor fields.

Defrise, Michel; Gullberg, Grant T.

2005-02-17

42

Breast mass detection using slice conspicuity in 3D reconstructed digital breast volumes  

Science.gov (United States)

In digital breast tomosynthesis, the three dimensional (3D) reconstructed volumes only provide quasi-3D structure information with limited resolution along the depth direction due to insufficient sampling in depth direction and the limited angular range. The limitation could seriously hamper the conventional 3D image analysis techniques for detecting masses because the limited number of projection views causes blurring in the out-of-focus planes. In this paper, we propose a novel mass detection approach using slice conspicuity in the 3D reconstructed digital breast volumes to overcome the above limitation. First, to overcome the limited resolution along the depth direction, we detect regions of interest (ROIs) on each reconstructed slice and separately utilize the depth directional information to combine the ROIs effectively. Furthermore, we measure the blurriness of each slice for resolving the degradation of performance caused by the blur in the out-of-focus plane. Finally, mass features are extracted from the selected in focus slices and analyzed by a support vector machine classifier to reduce the false positives. Comparative experiments have been conducted on a clinical data set. Experimental results demonstrate that the proposed approach outperforms the conventional 3D approach by achieving a high sensitivity with a small number of false positives.

Kim, Seong Tae; Kim, Dae Hoe; Ro, Yong Man

2014-09-01

43

3D density estimation in digital breast tomosynthesis: application to needle path planning for breast biopsy  

Science.gov (United States)

Needle insertion planning for digital breast tomosynthesis (DBT) guided biopsy has the potential to improve patient comfort and intervention safety. However, a relevant planning should take into account breast tissue deformation and lesion displacement during the procedure. Deformable models, like finite elements, use the elastic characteristics of the breast to evaluate the deformation of tissue during needle insertion. This paper presents a novel approach to locally estimate the Young's modulus of the breast tissue directly from the DBT data. The method consists in computing the fibroglandular percentage in each of the acquired DBT projection images, then reconstructing the density volume. Finally, this density information is used to compute the mechanical parameters for each finite element of the deformable mesh, obtaining a heterogeneous DBT based breast model. Preliminary experiments were performed to evaluate the relevance of this method for needle path planning in DBT guided biopsy. The results show that the heterogeneous DBT based breast model improves needle insertion simulation accuracy in 71% of the cases, compared to a homogeneous model or a binary fat/fibroglandular tissue model.

Vancamberg, Laurence; Geeraert, Nausikaa; Iordache, Razvan; Palma, Giovanni; Klausz, Rémy; Muller, Serge

2011-03-01

44

3D reconstruction of coronary artery using biplane angiography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper, we present a new method for the 3D reconstruction and visualization of coronary arteries in biplane angiography. The proposed method performs direct reconstruction of 3D coronary artery pathways without computing the 2D or 3D vessel centerlines. A front propagation algorithm is used to reconstruct the coronary artery pathways in 3D space. Starting from one or more 3D points, the front is expanded with a propagation speed controlled by the combined image information from two 2D ...

Law, Kwa; Zhu, H.; Chan, Fhy

2003-01-01

45

Multiscale regularized reconstruction for enhancing microcalcification in digital breast tomosynthesis  

Science.gov (United States)

Digital breast tomosynthesis (DBT) holds strong promise for improving the sensitivity of detecting subtle mass lesions. Detection of microcalcifications is more difficult because of high noise and subtle signals in the large DBT volume. It is important to enhance the contrast-to-noise ratio (CNR) of microcalcifications in DBT reconstruction. A major challenge of implementing microcalcification enhancement or noise regularization in DBT reconstruction is to preserve the image quality of masses, especially those with ill-defined margins and subtle spiculations. We are developing a new multiscale regularization (MSR) method for the simultaneous algebraic reconstruction technique (SART) to improve the CNR of microcalcifications without compromising the quality of masses. Each DBT slice is stratified into different frequency bands via wavelet decomposition and the regularization method applies different degrees of regularization to different frequency bands to preserve features of interest and suppress noise. Regularization is constrained by a characteristic map to avoid smoothing subtle microcalcifications. The characteristic map is generated via image feature analysis to identify potential microcalcification locations in the DBT volume. The MSR method was compared to the non-convex total pvariation (TpV) method and SART with no regularization (NR) in terms of the CNR and the full width at half maximum of the line profiles intersecting calcifications and mass spiculations in DBT of human subjects. The results demonstrated that SART regularized by the MSR method was superior to the TpV method for subtle microcalcifications in terms of CNR enhancement. The MSR method preserved the quality of subtle spiculations better than the TpV method in comparison to NR.

Lu, Yao; Chan, Heang-Ping; Wei, Jun; Hadjiiski, Lubomir; Zhou, Chuan

2012-03-01

46

Singular-value decomposition of a tomosynthesis system  

Science.gov (United States)

Tomosynthesis is an emerging technique with potential to replace mammography, since it gives 3D information at a relatively small increase in dose and cost. We present an analytical singular-value decomposition of a tomosynthesis system, which provides the measurement component of any given object. The method is demonstrated on an example object. The measurement component can be used as a reconstruction of the object, and can also be utilized in future observer studies of tomosynthesis image quality. PMID:20940966

Burvall, Anna; Barrett, Harrison H.; Myers, Kyle J.; Dainty, Christopher

2010-01-01

47

Singular-value decomposition of a tomosynthesis system  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Tomosynthesis is an emerging technique with potential to replace mammography, since it gives 3D information at a relatively small increase in dose and cost. We present an analytical singular-value decomposition of a tomosynthesis system, which provides the measurement component of any given object. The method is demonstrated on an example object. The measurement component can be used as a reconstruction of the object, and can also be utilized in future observer studies of tomosynthesis image ...

Burvall, Anna; Barrett, Harrison H.; Myers, Kyle J.; Dainty, Christopher

2010-01-01

48

Euclidean 3D Reconstruction of Unknown Objects from Multiple Images  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, we are interested in the problem of Euclidean 3D reconstruction of unknown objects by passive stereo vision method. Our method is based on the combination between Harris and Sift interest point detectors, to take advantage of the power of these two detectors, which will be useful when matching step, as a key step for 3D reconstruction, In order to have a sufficient number of matches distributed on the images. These matches will be used to estimate the 3D points (the projection matrices will be estimated after calibration using 3D Calibration Pattern. Finally, a 3D mesh is constructed by 3D Delaunay triangulation, applied to the 3D points reconstructed. Experimental results prove that this method is practical and gives satisfying results without going through the propagation step.

Soulaiman El Hazzat

2014-02-01

49

Generalization of Desargues Theorem for Sparse 3-D Reconstruction  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Visual perception for walking machines needs to handle more degrees of freedom than for wheeled robots. For humanoids, four or six legged robots, camera motion is a 6- D one instead of 3-D or planar motions. Classical 3-D reconstruction methods cannot be applied directly because explicit sensor motion is needed. In this paper, we propose an algorithm for 3-D reconstruction of an unstructured environment using a motion- free uncalibrated single camera. Computer vision techniques are employed t...

Fremont, Vincent; Chellali, Ryad; Fontaine, Jean-guy

2009-01-01

50

MMSE Reconstruction for 3D Freehand Ultrasound Imaging  

Directory of Open Access Journals (Sweden)

Full Text Available The reconstruction of 3D ultrasound (US images from mechanically registered, but otherwise irregularly positioned, B-scan slices is of great interest in image guided therapy procedures. Conventional 3D ultrasound algorithms have low computational complexity, but the reconstructed volume suffers from severe speckle contamination. Furthermore, the current method cannot reconstruct uniform high-resolution data from several low-resolution B-scans. In this paper, the minimum mean-squared error (MMSE method is applied to 3D ultrasound reconstruction. Data redundancies due to overlapping samples as well as correlation of the target and speckle are naturally accounted for in the MMSE reconstruction algorithm. Thus, the reconstruction process unifies the interpolation and spatial compounding. Simulation results for synthetic US images are presented to demonstrate the excellent reconstruction.

Yibin Zheng

2008-03-01

51

Fully Automatic 3D Reconstruction of Histological Images  

CERN Document Server

In this paper, we propose a computational framework for 3D volume reconstruction from 2D histological slices using registration algorithms in feature space. To improve the quality of reconstructed 3D volume, first, intensity variations in images are corrected by an intensity standardization process which maps image intensity scale to a standard scale where similar intensities correspond to similar tissues. Second, a subvolume approach is proposed for 3D reconstruction by dividing standardized slices into groups. Third, in order to improve the quality of the reconstruction process, an automatic best reference slice selection algorithm is developed based on an iterative assessment of image entropy and mean square error of the registration process. Finally, we demonstrate that the choice of the reference slice has a significant impact on registration quality and subsequent 3D reconstruction.

Bagci, Ulas

2009-01-01

52

The PRISM3D paleoenvironmental reconstruction  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Pliocene Research, Interpretation and Synoptic Mapping (PRISM) paleoenvironmental reconstruction is an internally consistent and comprehensive global synthesis of a past interval of relatively warm and stable climate. It is regularly used in model studies that aim to better understand Pliocene climate, to improve model performance in future climate scenarios, and to distinguish model-dependent climate effects. The PRISM reconstruction is constantly evolving in order to incorporate additio...

Dowsett, H.; Robinson, M.; Haywood, A. M.; Salzmann, U.; Hill, Daniel; Sohl, L. E.; Chandler, M.; Williams, Mark; Foley, K.; Stoll, D. K.

2010-01-01

53

Breast mass characterization using 3D automated ultrasound as an adjunct to digital breast tomosynthesis: A pilot study  

Science.gov (United States)

Objective To retrospectively evaluate the effect of 3D automated ultrasound (3D-AUS) as an adjunct to digital breast tomosynthesis (DBT) on radiologists’ performance and confidence in discriminating malignant and benign breast masses. Methods Two-view DBT (CC and MLO or Lateral) and single-view 3D-AUS were acquired on 51 patients with (subsequently) biopsy-proven masses (13 malignant, 38 benign). Six experienced radiologists rated, on a 13-point scale, the likelihood of malignancy of an identified mass, first by reading the DBT alone, followed immediately by reading the DBT with automatically co-registered 3D-AUS. The diagnostic performance of each method was measured using ROC analysis. and changes in sensitivity and specificity with the McNemar test. After each reading, radiologists took a survey to rate their confidence level in using DBT alone vs combined DBT/3D-AUS as potential screening modalities. Results The six radiologists had an average area under the ROC curve of 0.92 for both modalities (range 0.89–0.97 for DBT, 0.90–0.94 for DBT/3D-AUS). With BI-RADS rating of 4 as the threshold for biopsy recommendation, the average sensitivity of the radiologists increased from 96% to 100% (p>0.08) with 3D-AUS, while the specificity decreased from 33% to 25% (p>0.28). Survey responses indicated an increased confidence in potentially using DBT for screening when 3D-AUS was added (p<0.05 for each reader). Conclusions In this initial reader study, no significant difference in ROC performance was found with the addition of 3D-AUS to DBT. However, a trend to an improved discrimination of malignancy was observed when adding 3D-AUS. Radiologists’ confidence also improved with DBT/3DAUS compared to DBT alone. PMID:23269714

Padilla, Frederic; Roubidoux, Marilyn A.; Paramagul, Chintana; Sinha, Sumedha P.; Goodsitt, Mitchell M.; Le Carpentier, Gerald L.; Chan, Heang-Ping; Hadjiiski, Lubomir M.; Fowlkes, Brian J.; Joe, Annette D.; Klein, Katherine A.; Nees, Alexis V.; Noroozian, Mitra; Patterson, Stephanie K.; Pinsky, Renee W.; Hooi, Fong Ming; Carson, Paul L.

2013-01-01

54

ECG gated tomographic reconstruction for 3-D rotational coronary angiography  

Science.gov (United States)

A method is proposed for 3-D reconstruction of coronary from a limited number of projections in rotational angiography. A Bayesian maximum a posteriori (MAP) estimation is applied with a Poisson distributed projection to reconstruct the 3D coronary tree at a given instant of the cardiac cycle. Several regularizers are investigated L0-norm, L1 and L2 -norm in order to take into account the sparsity of the data. Evaluations are reported on simulated data obtained from a 3D dynamic sequence acquired on a 64-slice GE LightSpeed CT scan. A performance study is conducted to evaluate the quality of the reconstruction of the structures. PMID:21096844

Hu, Yining; Xie, Lizhe; Nunes, Jean Claude; Bellanger, Jean Jacques; Bedossa, Marc; Toumoulin, Christine

2010-01-01

55

A novel digital tomosynthesis (DTS) reconstruction method using a deformation field map  

International Nuclear Information System (INIS)

We developed a novel digital tomosynthesis (DTS) reconstruction method using a deformation field map to optimally estimate volumetric information in DTS images. The deformation field map is solved by using prior information, a deformation model, and new projection data. Patients' previous cone-beam CT (CBCT) or planning CT data are used as the prior information, and the new patient volume to be reconstructed is considered as a deformation of the prior patient volume. The deformation field is solved by minimizing bending energy and maintaining new projection data fidelity using a nonlinear conjugate gradient method. The new patient DTS volume is then obtained by deforming the prior patient CBCT or CT volume according to the solution to the deformation field. This method is novel because it is the first method to combine deformable registration with limited angle image reconstruction. The method was tested in 2D cases using simulated projections of a Shepp-Logan phantom, liver, and head-and-neck patient data. The accuracy of the reconstruction was evaluated by comparing both organ volume and pixel value differences between DTS and CBCT images. In the Shepp-Logan phantom study, the reconstructed pixel signal-to-noise ratio (PSNR) for the 60 deg. DTS image reached 34.3 dB. In the liver patient study, the relative error of the liver volume reconstructed using 60 deg. projections was 3.4%. The reconstructed PSNR for the 60 deg. DTS image reached 23.5 dB. In the head-and-neck patient study, the new method using 60 deg. projections was able to reconstruct the 8.1 deg. rotation of the bony structure with 0.0 deg. error. The reconstructed PSNR for the 60 deg. DTS image reached 24.2 dB. In summary, the new reconstruction method can optimally estimate the volumetric information in DTS images using 60 deg. projections. Preliminary validation of the algorithm showed that it is both technically and clinically feasible for image guidance in radiation therapy

56

3D Beam Reconstruction by Fluorescence Imaging  

CERN Document Server

We present a technique for mapping the complete 3D spatial intensity profile of a laser beam from its fluorescence in an atomic vapour. We propagate shaped light through a rubidium vapour cell and record the resonant scattering from the side. From a single measurement we obtain a camera limited resolution of 200 x 200 transverse points and 659 longitudinal points. In constrast to invasive methods in which the camera is placed in the beam path, our method is capable of measuring patterns formed by counterpropagating laser beams. It has high resolution in all 3 dimensions, is fast and can be completely automated. The technique has applications in areas which require complex beam shapes, such as optical tweezers, atom trapping and pattern formation.

Radwell, Neal; Franke-Arnold, Sonja

2013-01-01

57

A comparative study of limited-angle cone-beam reconstruction methods for breast tomosynthesis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Digital tomosynthesis mammography (DTM) is a promising new modality for breast cancer detection. In DTM, projection-view images are acquired at a limited number of angles over a limited angular range and the imaged volume is reconstructed from the two-dimensional projections, thus providing three-dimensional structural information of the breast tissue. In this work, we investigated three representative reconstruction methods for this limited-angle cone-beam tomographic problem, including the ...

Zhang, Yiheng; Chan, Heang-ping; Sahiner, Berkman; Wei, Jun; Goodsitt, Mitchell M.; Hadjiiski, Lubomir M.; Ge, Jun; Zhou, Chuan

2006-01-01

58

ECG gated tomographic reconstruction for 3-D rotational coronary angiography.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A method is proposed for 3-D reconstruction of coronary from a limited number of projections in rotational angiography. A Bayesian maximum a posteriori (MAP) estimation is applied with a Poisson distributed projection to reconstruct the 3D coronary tree at a given instant of the cardiac cycle. Several regularizers are investigated L0-norm, L1 and L2 -norm in order to take into account the sparsity of the data. Evaluations are reported on simulated data obtained from a 3D dynamic sequence acqu...

Hu, Yining; Xie, Lizhe; Nunes, Jean Claude; Bellanger, Jean Jacques; Bedossa, Marc; Toumoulin, Christine

2010-01-01

59

3D fast reconstruction in positron emission tomography  

International Nuclear Information System (INIS)

The issue of long reconstruction times in positron emission tomography (PET) has been addressed from several points of view, resulting in an affordable dedicated system capable of handling routine 3D reconstructions in a few minutes per frame : on the hardware side using fast processors and a parallel architecture, and on the software side, using efficient implementation of computationally less intensive algorithms

60

Strategy for 3D Reconstruction of Industrial Rubber Part  

Directory of Open Access Journals (Sweden)

Full Text Available The motivation for this paper comes from problems involved with the 3D surface reconstruction of the black components in rubber industry. In this paper, a stereo vision system made by two low-cost cameras, a multi-media projector is explained at first. In order to calibrate cameras, an algorithm based on quaternion attitude description is applied to simplify initial values achieving procedure and overcome the correlation problems of the least square estimation based on 2D planar pattern. A method combined with gray code and epipolar geometry is adopted to deal with the matching problem without texture. The whole mathematical algorithms for 3D space coordinates are proposed based on the linear computation and nonlinear space intersection from stereo vision. The experimental results shows that the relative accuracy for 3D reconstruction could reach 1/10000. This indicated that the methods used in this paper were feasible for 3D reconstruction of textureless objects.

Hongxia Cui

2012-02-01

 
 
 
 
61

Tomographic compressive holographic reconstruction of 3D objects  

Science.gov (United States)

Compressive holography with multiple projection tomography is applied to solve the inverse ill-posed problem of reconstruction of 3D objects with high axial accuracy. To visualize the 3D shape, we propose Digital Tomographic Compressive Holography (DiTCH), where projections from more than one direction as in tomographic imaging systems can be employed, so that a 3D shape with better axial resolution can be reconstructed. We compare DiTCH with single-beam holographic tomography (SHOT) which is based on Fresnel back-propagation. A brief theory of DiTCH is presented, and experimental results of 3D shape reconstruction of objects using DITCH and SHOT are compared.

Nehmetallah, G.; Williams, L.; Banerjee, P. P.

2012-10-01

62

3D Reconstruction of an Erupting Prominence  

Science.gov (United States)

A bright prominence associated with a CME was seen erupting from the Sun on April 9, 2008. This prominence was tracked in both the STEREO EUVI and COR1 telescopes, and was seen to undergo complex churning motions as it erupted. Although the STEREO separation was 48 degrees, it was possible to match some sharp features in the later part of the eruption as seen in the 304 A line in EUVI by both STEREO Ahead and Behind. These features could then be traced out in three-dimensional space, and reprojected into a view in which the eruption is directed towards the observer. The reconstructed view shows that the alignment of the prominence rotates as it rises through the EUVI field-of-view out to 1.4 solar radii, and then remains constant as seen by COR1. The final alignment differed by about 140 degrees from the original filament orientation.

Thompson, W. T.

2008-12-01

63

New 3D reconstruction approach for 3D object recognition in intelligent assembly system  

Science.gov (United States)

In this paper, a new 3D reconstruction approach for 3D object recognition in neuro-vision system is presented. First, a phase based stereo matching using Hopfield neural network approach is presented. The stereo matching problems are treated in frequency domain by using local phase. Instead of matching feature or texture of images, the stereo matching process is performed by using local phases of left image and right image in stereo image pair. By using the windowed Fourier transform, the windowed Fourier phases can be calculated. Through the variable window Gabor filter, the local phases of image can also be obtained. The Hopfield neural network is adopted to implement the stereo matching process. A suitable architecture of neural network is established, so that the computation can be implemented efficiently in parallel. A suitable matching function is created by using the local phase property. The energy function for neural network is constructed with satisfying some necessary constraints. The stereo matching process then is carried to find the minimum energy corresponding to the solution of the problem. Second, a 3D object reconstruction neural network is constructed by using BP neural network. So the 3D configuration and shape can be reconstructed by this neural network. With multiple neural networks the 3D reconstruction processes can be performed in parallel. The examples for both synthetic and real images are shown in the experiment, and good results are obtained.

Xiong, Yingen; Zhang, Guangzhao

1998-03-01

64

3D refraction-corrected transmission reconstruction for 3D ultrasound computer tomography  

Science.gov (United States)

Speed of sound imaging is an important modality used in medical ultrasound applications. We developed a 3D ultrasound computer tomograph (3D USCT) which is capable of reflection and transmission tomography. Most 3D tomography reconstruction methods like the algebraic reconstruction technique rely on the assumption that the transmission rays propagate straightly from emitter to receiver, which is not valid for ultrasound. Due to refractions in the tissue the rays are bent rather than straight. To overcome this problem we use a 3D Eikonal solver that calculates the bent ray paths for the transmission pulses and include it into our Compressive Sampling reconstruction framework. Using an iterative scheme we show results for synthetic and real data. The shape and the outline of the phantoms reconstructed with the bent-ray method match the reflection reconstructions better and for synthetic data the speed of sound is closer to the speed of sound in the phantom by approximately 1.2 m/s.

Dapp, Robin; Gemmeke, Hartmut; Ruiter, Nicole

2012-03-01

65

Reconstruction of High Resolution 3D Objects from Incomplete Images and 3D Information  

Directory of Open Access Journals (Sweden)

Full Text Available To this day, digital object reconstruction is a quite complex area that requires many techniques and novel approaches, in which high-resolution 3D objects present one of the biggest challenges. There are mainly two different methods that can be used to reconstruct high resolution objects and images: passive methods and active methods. This methods depend on the type of information available as input for modeling 3D objects. The passive methods use information contained in the images and the active methods make use of controlled light sources, such as lasers. The reconstruction of 3D objects is quite complex and there is no unique solution- The use of specific methodologies for the reconstruction of certain objects it’s also very common, such as human faces, molecular structures, etc. This paper proposes a novel hybrid methodology, composed by 10 phases that combine active and passive methods, using images and a laser in order to supplement the missing information and obtain better results in the 3D object reconstruction. Finally, the proposed methodology proved its efficiency in two complex topological complex objects.

Alexander Pacheco

2014-05-01

66

3D Equilibrium Reconstruction in Stellarators and Tokamaks with STELLOPT  

Science.gov (United States)

The ability to model and predict the behavior of stellarators and tokamaks requires an ability to match simulation parameters with experimental measurements. This process, known as experimental reconstruction, has been used extensively with 2D axisymmetric codes for Tokamaks. These codes, such as EFIT, lack the ability to model the 3D nature of stellarators and the emerging 3D nature of Tokamaks. Phenomena such as, shielding of islands by neoclassical flows and the suppression of edge localized modes through application of 3D fields, highlight the need for such 3D tools. The stellarator optimizer code STELLOPT has been modified to match 3D VMEC equilibria to experimental measurements. This has allowed 3D experimental reconstructions to be preformed on W7-AS, LHD, and DIII-D devices. The free boundary VMEC equilibria are matched to Thomson profiles (ne and Te), charge exchange measurements (Ti), MSE (polarization angle), and magnetic diagnostics (B-probes, flux loops, Rogowski coils). Three dimensional reconstructed equilibria are presented alongside confidence metrics for the reconstruction process.

Lazerson, Samuel; Pablant, Novimir; Gates, David; Neilson, Hutch; Nazikian, Raffi; Suzuki, Yasuhiro; Watanabe, Kiyomasa; Ida, Katsumi; Sakakibara, Satoru

2012-10-01

67

Sensorless reconstruction of unconstrained freehand 3D ultrasound data.  

Science.gov (United States)

Freehand 3D ultrasound can be acquired without a position sensor by finding the separations of pairs of frames using information in the images themselves. Previous work has not considered how to reconstruct entirely freehand data, which can exhibit irregularly spaced frames, intersecting frames, nonmonotonic out-of-plane probe motion and significant in-plane motion. This paper presents reconstruction methods that overcome these limitations and are able to robustly reconstruct unconstrained freehand data. The methods are assessed on freehand data sets and compared with reconstructions obtained with a position sensor. PMID:17280771

Housden, R James; Gee, Andrew H; Treece, Graham M; Prager, Richard W

2007-03-01

68

Sensorless reconstruction of freehand 3D ultrasound data.  

Science.gov (United States)

Freehand 3D ultrasound can be acquired without a position sensor by finding the separations of pairs of frames using information in the images themselves. Previous work has not considered how to reconstruct entirely freehand data, which can exhibit irregularly spaced frames, non-monotonic out-of-plane probe motion and significant inplane motion. This paper presents reconstruction methods that overcome these limitations and are able to robustly reconstruct freehand data. The methods are assessed on freehand data sets and compared to reconstructions obtained using a position sensor. PMID:17354792

Housden, R James; Gee, Andrew H; Treece, Graham M; Prager, Richard W

2006-01-01

69

3D reconstruction for the detection of cranial anomalies  

International Nuclear Information System (INIS)

There is a growing interest in the use of three-dimensional (3D) cranial reconstruction from CT scans for surgical planning. A low-cost imaging system has been developed, which provides pseudo-3D images which may be manipulated to reveal the craniofacial skeleton as a whole or any particular component region. The contrast between congenital (hydrocephalic), normocephalic and acquired (carcinoma of the maxillary sinus) anomalous cranial forms demonstrates the potential of this system

70

3D DICOM IMAGES RECONSTRUCTION USING LAB VIEW  

Directory of Open Access Journals (Sweden)

Full Text Available Three dimensional image reconstruction based on two dimensional images has excellent utilities, analyzing the defects in the medical field. 2D image does not have accurate information but 3D have more accuracy. 3D image techniques have been mostly used in DICOM images and also used in image processing applications. In this paper 2D images were taken by using computed tomography, MRI scanners have excellent characteristics and reconstruct the 3D image by using surface rendering technique by implementing the marching cubes algorithm in Lab VIEW based platform. Analysis using 2- D images have certain drawbacks such as intensity and color of the same physical positions may vary considerably across series of images. In this paper implements two things. First one is 2D image registration using image read and second one is create iso-surfaces , iso-normals using marching cubes algorithm and finally reconstruct the 3d image. In this applied series of 2D images such as DICOM images from MRI scanner and developed 3D reconstructed image. Developed code for that using Lab VIEW software which is of lower cost and of acceptable performance.

K. SUDHARANI

2014-01-01

71

3D surface reconstruction multi-scale hierarchical approaches  

CERN Document Server

3D Surface Reconstruction: Multi-Scale Hierarchical Approaches presents methods to model 3D objects in an incremental way so as to capture more finer details at each step. The configuration of the model parameters, the rationale and solutions are described and discussed in detail so the reader has a strong understanding of the methodology. Modeling starts from data captured by 3D digitizers and makes the process even more clear and engaging. Innovative approaches, based on two popular machine learning paradigms, namely Radial Basis Functions and the Support Vector Machines, are also introduced

Bellocchio, Francesco; Ferrari, Stefano; Piuri, Vincenzo

2012-01-01

72

NeuralNetwork Based 3D Surface Reconstruction  

CERN Document Server

This paper proposes a novel neural-network-based adaptive hybrid-reflectance three-dimensional (3-D) surface reconstruction model. The neural network combines the diffuse and specular components into a hybrid model. The proposed model considers the characteristics of each point and the variant albedo to prevent the reconstructed surface from being distorted. The neural network inputs are the pixel values of the two-dimensional images to be reconstructed. The normal vectors of the surface can then be obtained from the output of the neural network after supervised learning, where the illuminant direction does not have to be known in advance. Finally, the obtained normal vectors can be applied to integration method when reconstructing 3-D objects. Facial images were used for training in the proposed approach

Joseph, Vincy

2009-01-01

73

Using simulated annealing for 3D reconstruction of orthopedic fracture  

International Nuclear Information System (INIS)

Three-dimensional (3D) reconstruction from two orthogonal images has been realized, and a Monte Carlo program MCNP4B has been applied to simulate the x-ray images. These two approaches can be applied to reconstruction of orthopedic fractures, using computed radiography images. The purpose of this paper is to utilize the information from pairs of orthogonal images at different stages of healing to generate a 3D reconstruction of the callus which builds up during the treatment, thus facilitating understanding and enabling assessment of the process of fracture healing. The reconstruction from Monte Carlo simulated images and x-ray images shows that this approach may be feasible in clinical practice

74

Pre-computed backprojection based penalized-likelihood (PPL) reconstruction with an edge-preserved regularizer for stationary Digital Breast Tomosynthesis  

Science.gov (United States)

Stationary Digital Breast Tomosynthesis (sDBT) is a carbon nanotube based breast imaging device with fast data acquisition and decent projection resolution to provide three dimensional (3-D) volume information. To- mosynthesis 3-D image reconstruction is faced with the challenges of the cone beam geometry and the incomplete and nonsymmetric sampling due to the sparse views and limited view angle. Among all available reconstruction methods, statistical iterative method exhibits particular promising since it relies on an accurate physical and statistical model with prior knowledge. In this paper, we present the application of an edge-preserved regularizer to our previously proposed precomputed backprojection based penalized-likelihood (PPL) reconstruction. By using the edge-preserved regularizer, our experiments show that through tuning several parameters, resolution can be retained while noise is reduced significantly. Compared to other conventional noise reduction techniques in image reconstruction, less resolution is lost in order to gain certain noise reduction, which may benefit the research of low dose tomosynthesis.

Xu, Shiyu; Inscoe, Christy R.; Lu, Jianping; Zhou, Otto; Chen, Ying

2014-03-01

75

Filtering of measurement noise with the 3D reconstruction algorithm  

DEFF Research Database (Denmark)

Two different antenna models are set up in GRASP and CHAMP, and noise is added to the radiated field. The noisy field is then given as input to the 3D reconstruction of DIATOOL and the SWE coefficients and the far-field radiated by the reconstructed currents are compared with the noise-free results coming from GRASP and CHAMP. The obtained results are presented and discussed.

Cappellin, Cecilia; Pivnenko, Sergey

2014-01-01

76

Software for 3D diagnostic image reconstruction and analysis  

International Nuclear Information System (INIS)

Recent advances in computer technologies have opened new frontiers in medical diagnostics. Interesting possibilities are the use of three-dimensional (3D) imaging and the combination of images from different modalities. Software prepared in our laboratories devoted to 3D image reconstruction and analysis from computed tomography and ultrasonography is presented. In developing our software it was assumed that it should be applicable in standard medical practice, i.e. it should work effectively with a PC. An additional feature is the possibility of combining 3D images from different modalities. The reconstruction and data processing can be conducted using a standard PC, so low investment costs result in the introduction of advanced and useful diagnostic possibilities. The program was tested on a PC using DICOM data from computed tomography and TIFF files obtained from a 3D ultrasound system. The results of the anthropomorphic phantom and patient data were taken into consideration. A new approach was used to achieve spatial correlation of two independently obtained 3D images. The method relies on the use of four pairs of markers within the regions under consideration. The user selects the markers manually and the computer calculates the transformations necessary for coupling the images. The main software feature is the possibility of 3D image reconstruction from a series of two-dimensional (2D) images. The reconstructed 3D image can be: (1) viewed with the most popular mcan be: (1) viewed with the most popular methods of 3D image viewing, (2) filtered and processed to improve image quality, (3) analyzed quantitatively (geometrical measurements), and (4) coupled with another, independently acquired 3D image. The reconstructed and processed 3D image can be stored at every stage of image processing. The overall software performance was good considering the relatively low costs of the hardware used and the huge data sets processed. The program can be freely used and tested (source code and program available at http://www.biofizyka.cm-uj.krakow.pl). Improvements allowing the processing of new data types and new procedures can be implemented for specific demands. (author)

77

QUANTITATIVE 3D RECONSTRUCTIONS AS IDENTIFICATION TOOL IN HEART DEVELOPMENT  

Directory of Open Access Journals (Sweden)

Full Text Available A method for displaying quantitative information in 3D reconstructions of the embryonic heart was developed to investigate spatial distributions of cell division and cell density. The method utilizes serial sections to extract morphological as well as quantitative data. The morphological data are used to reconstruct the embryonic heart and the quantitative data are classified and superimposed on the resulting reconstruction. The bias, which would result from size differences between cell populations, was investigated. If present, it would influence the absolute number of particles (nuclei per volume, although the classification applied on the reconstruction displaying the mitotic fraction remains unchanged. Although the reconstruction displaying the local densities is influenced by the bias, less than 2.5% of the regions is misclassified.

Alexandre T Soufan

2011-05-01

78

Improvement of geometrical measurements from 3D-SEM reconstructions  

DEFF Research Database (Denmark)

The quantification of 3D geometry at the nanometric scale is a major metrological challenge. In this work geometrical measurements on cylindrical items obtained with a 3D-SEM were investigated. Two items were measured: a wire gauge having a 0.25 mm nominal diameter and a hypodermic needle having an external diameter of 0.26mm. A series of measurements were performed to determine the accuracy of 3D reconstructions obtained using stereo-photogrammetry methods, finding a procedure to determine the optimum number of rotations of the object for an acceptable measuring uncertainty. It was determined that the diameter estimation performed using the 3D-SEM leads to an overestimation of approx. 7% compared to the reference values obtained using a 1-D length measuring machine. Standard deviation of SEM measurements performed on the wire gauge is approx. 1.5 times lower than the one performed on the hypodermic needle.

Carli, Lorenzo Technical University of Denmark,

2009-01-01

79

Exposing digital image forgeries by 3D reconstruction technology  

Science.gov (United States)

Digital images are easy to tamper and edit due to availability of powerful image processing and editing software. Especially, forged images by taking from a picture of scene, because of no manipulation was made after taking, usual methods, such as digital watermarks, statistical correlation technology, can hardly detect the traces of image tampering. According to image forgery characteristics, a method, based on 3D reconstruction technology, which detect the forgeries by discriminating the dimensional relationship of each object appeared on image, is presented in this paper. This detection method includes three steps. In the first step, all the parameters of images were calibrated and each crucial object on image was chosen and matched. In the second step, the 3D coordinates of each object were calculated by bundle adjustment. In final step, the dimensional relationship of each object was analyzed. Experiments were designed to test this detection method; the 3D reconstruction and the forged image 3D reconstruction were computed independently. Test results show that the fabricating character in digital forgeries can be identified intuitively by this method.

Wang, Yongqiang; Xu, Xiaojing; Li, Zhihui; Liu, Haizhen; Li, Zhigang; Huang, Wei

2009-11-01

80

Twenty-fold acceleration of 3D projection reconstruction MPI  

Science.gov (United States)

We experimentally demonstrate a 20-fold improvement in acquisition time in projection reconstruction (PR) magnetic particle imaging (MPI) relative to the state-of-the-art PR MPI imaging results. We achieve this acceleration in our imaging system by introducing an additional Helmholtz electromagnet pair, which creates a slow shift (focus) field. Because of magnetostimulation limits in humans, we show that scan time with three-dimensional (3D) PR MPI is theoretically within the same order of magnitude as 3D MPI with a field free point; however, PR MPI has an order of magnitude signal-to-noise ratio gain. PMID:23940058

Goodwill, Patrick W.; Saritas, Emine Ulku; Zheng, Bo; Lu, Kuan; Conolly, Steven M.

2014-01-01

 
 
 
 
81

Deformable Surface 3D Reconstruction from Monocular Images  

CERN Document Server

Being able to recover the shape of 3D deformable surfaces from a single video stream would make it possible to field reconstruction systems that run on widely available hardware without requiring specialized devices. However, because many different 3D shapes can have virtually the same projection, such monocular shape recovery is inherently ambiguous. In this survey, we will review the two main classes of techniques that have proved most effective so far: The template-based methods that rely on establishing correspondences with a reference image in which the shape is already known, and non-rig

Salzmann, Matthieu

2010-01-01

82

3-D Equilibrium Reconstruction in the HSX Stellarator  

Science.gov (United States)

Axisymmetric toroidal devices reconstruct the MHD equilibrium properties from measured pressure, magnetic field components, external field coil currents, and other diagnostics, by solving the Grad-Shafranov equation. For modern toroidal systems including advanced stellarators and tokamaks with asymmetric fields, such as those that arise from finite toroidal ripple or ferromagnetic blanket materials, a 3-D equilibrium reconstruction is required to account for non-axisymmetric effects and accurately determine the plasma profiles. The 3-D equilibrium reconstruction of plasma current and pressure profiles in the quasi-helically symmetric stellarator HSX is presented. The equilibrium currents in the HSX stellarator are measured with a set of magnetic diagnostics, which includes Rogowski coils, diamagnetic loops, two poloidal `belts' that are separated by 1/3 of a field period, and internal coils. Each belt consists of 16 3-axis magnetic pick-up coils to measure the local magnetic field, and 15 internal coils measure the poloidal field. V3FIT [1], a 3-D equilibrium reconstruction code, is used to reconstruct the pressure and current profile from the measured fields and fluxes. Reconstructions based on the external diagnostics confirm that the Pfirsch-Schl"uter current is helical due to the lack of toroidal curvature in HSX. The reconstruction of the pressure profile and stored energy based on the internal poloidal array agrees well with that measured by Thomson scattering and the flux loop. Later in time, the measurements are dominated by the bootstrap current which rises on a timescale comparable to the length of the discharge. The reconstruction of the current profile is consistent with the neoclassical bootstrap current when the effects of momentum conservation between plasma species [2] and the 3-D inductive response of the plasma column [3] are considered. The magnitude of the Pfirsch-Schl"uter and bootstrap currents are reduced by the high effective transform (˜3), which is characteristic of quasi-helically symmetric systems. The level of uncertainty in the reconstructed pressure and current profiles is largest near the core of the plasma. [4pt] [1] J.D. Hanson, et al, Nucl. Fusion 49 (2009) 075031. [0pt] [2] D.A. Spong, Phys. Plasmas 12, (2005) 056114. [0pt] [3] P.I Strand and W.A. Houlberg, Phys. Plasmas 8 (2001) 2782.

Schmitt, J. C.

2011-11-01

83

2D and 3D registration methods for dual-energy contrast-enhanced digital breast tomosynthesis  

Science.gov (United States)

Contrast-enhanced digital breast tomosynthesis (CE-DBT) uses an iodinated contrast agent to image the threedimensional breast vasculature. The University of Pennsylvania is conducting a CE-DBT clinical study in patients with known breast cancers. The breast is compressed continuously and imaged at four time points (1 pre-contrast; 3 postcontrast). A hybrid subtraction scheme is proposed. First, dual-energy (DE) images are obtained by a weighted logarithmic subtraction of the high-energy and low-energy image pairs. Then, post-contrast DE images are subtracted from the pre-contrast DE image. This hybrid temporal subtraction of DE images is performed to analyze iodine uptake, but suffers from motion artifacts. Employing image registration further helps to correct for motion, enhancing the evaluation of vascular kinetics. Registration using ANTS (Advanced Normalization Tools) is performed in an iterative manner. Mutual information optimization first corrects large-scale motions. Normalized cross-correlation optimization then iteratively corrects fine-scale misalignment. Two methods have been evaluated: a 2D method using a slice-by-slice approach, and a 3D method using a volumetric approach to account for out-of-plane breast motion. Our results demonstrate that iterative registration qualitatively improves with each iteration (five iterations total). Motion artifacts near the edge of the breast are corrected effectively and structures within the breast (e.g. blood vessels, surgical clip) are better visualized. Statistical and clinical evaluations of registration accuracy in the CE-DBT images are ongoing.

Lau, Kristen C.; Roth, Susan; Maidment, Andrew D. A.

2014-03-01

84

Clinical Performance Metrics of 3D Digital Breast Tomosynthesis Compared With 2D Digital Mammography for Breast Cancer Screening in Community Practice.  

Science.gov (United States)

OBJECTIVE. The objective of our study was to assess the clinical performance of combined 2D-3D digital breast tomosynthesis (DBT), referred to as "3D DBT," compared with 2D digital mammography (DM) alone for screening mammography in a community-based radiology practice. MATERIALS AND METHODS. Performance outcomes measures were assessed for 14 radiologists who interpreted more than 500 screening mammography 3D DBT studies after the initiation of tomosynthesis. Outcomes from screening mammography during the study period between August 9, 2011, and November 30, 2012, using 3D DBT (n = 23,149 patients) versus 2D DM (n = 54,684 patients) were compared. RESULTS. For patients screened with 3D DBT, the relative change in recall rate was 16.1% lower than for patients screened with 2D DM (p > 0.0001). The overall cancer detection rate (CDR), expressed as number of cancers per 1000 patients screened, was 28.6% greater (p = 0.035) for 3D DBT (6.3/1000) compared with 2D DM (4.9/1000). The CDR for invasive cancers with 3D DBT (4.6/1000) was 43.8% higher (p = 0.0056) than with 2D DM (3.2/1000). The positive predictive value for recalls from screening (PPV1) was 53.3% greater (p = 0.0003) for 3D DBT (4.6%) compared with 2D DM (3.0%). No significant difference in the positive predictive value for biopsy (PPV3) was found for 3D DBT versus 2D DM (22.8% and 23.8%, respectively) (p = 0.696). CONCLUSION. In community-based radiology practice, mammography screening with 3D DBT yielded lower recall rates, an increased CDR for cancer overall, and an increased CDR for invasive cancer compared with 2D DM. The PPV1 was significantly greater in the group screened using 3D DBT. PMID:24918774

Greenberg, Julianne S; Javitt, Marcia C; Katzen, Jason; Michael, Sara; Holland, Agnes E

2014-09-01

85

3D Reconstruction of Extensive Air Showers from Fluorescence Data  

CERN Document Server

A new method to reconstruct the 3-dimensional structure of extensive air showers, seen by fluorescence detectors, is proposed. The observation of the shower is done in 2-dimensional pixels, for consecutive time bins. Time corresponds to a third dimension. Assuming that the cosmic ray shower propagates as a plane wave front moving at the speed of light, a complex 3D volume in space can be associated to each measured charge (per pixel and time bin). The 3D description in space allows a simultaneous access to the longitudinal and lateral profiles of each shower. In the case that several eyes observe the same shower, the method gives a straight-forward combination of all the information. This method is in an early phase of development and is not used for the general reconstruction of the Auger data.

Andringa, S; Pimenta, M

2007-01-01

86

Reconstruction 3d Des Artères Coronaires En Imagerie Rotationnelle Rx  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Nous présentons une méthode de reconstruction 3D des artères coronaires à partir de 4 projections acquises en imagerie rotationnelle R-X. L'approche retenue considère un problème d'optimisation d'une fonction "objectif", en se basant sur un estimateur Bayésien (MAP : Maximum à postériori) et un modèle de distribution des données de projection de type Poisson. Le problème étant sous déterminé, nous introduisons un a priori afin d'améliorer la convergence de l'algorithme. Trois ...

Oukili, Ahmed; Hu, Yining; Nunes, Jean-claude; Bedossa, Marc; Luo, Limin; Toumoulin, Christine

2011-01-01

87

Projective 3D-reconstruction of Uncalibrated Endoscopic Images  

Directory of Open Access Journals (Sweden)

Full Text Available The most common medical diagnostic method for urinary bladder cancer is cystoscopy. This inspection of the bladder is performed by a rigid endoscope, which is usually guided close to the bladder wall. This causes a very limited field of view; difficulty of navigation is aggravated by the usage of angled endoscopes. These factors cause difficulties in orientation and visual control. To overcome this problem, the paper presents a method for extracting 3D information from uncalibrated endoscopic image sequences and for reconstructing the scene content. The method uses the SURF-algorithm to extract features from the images and relates the images by advanced matching. To stabilize the matching, the epipolar geometry is extracted for each image pair using a modified RANSAC-algorithm. Afterwards these matched point pairs are used to generate point triplets over three images and to describe the trifocal geometry. The 3D scene points are determined by applying triangulation to the matched image points. Thus, these points are used to generate a projective 3D reconstruction of the scene, and provide the first step for further metric reconstructions.

P. Faltin

2010-01-01

88

Weighted simultaneous algebraic reconstruction technique for tomosynthesis imaging of objects with high-attenuation features  

International Nuclear Information System (INIS)

Purpose: This paper introduces a nonlinear weighting scheme into the backprojection operation within the simultaneous algebraic reconstruction technique (SART). It is designed for tomosynthesis imaging of objects with high-attenuation features in order to reduce limited angle artifacts. Methods: The algorithm estimates which projections potentially produce artifacts in a voxel. The contribution of those projections into the updating term is reduced. In order to identify those projections automatically, a four-dimensional backprojected space representation is used. Weighting coefficients are calculated based on a dissimilarity measure, evaluated in this space. For each combination of an angular view direction and a voxel position an individual weighting coefficient for the updating term is calculated. Results: The feasibility of the proposed approach is shown based on reconstructions of the following real three-dimensional tomosynthesis datasets: a mammography quality phantom, an apple with metal needles, a dried finger bone in water, and a human hand. Datasets have been acquired with a Siemens Mammomat Inspiration tomosynthesis device and reconstructed using SART with and without suggested weighting. Out-of-focus artifacts are described using line profiles and measured using standard deviation (STD) in the plane and below the plane which contains artifact-causing features. Artifacts distribution in axial direction is measured using an artifact spread function (ASF). Tusing an artifact spread function (ASF). The volumes reconstructed with the weighting scheme demonstrate the reduction of out-of-focus artifacts, lower STD (meaning reduction of artifacts), and narrower ASF compared to nonweighted SART reconstruction. It is achieved successfully for different kinds of structures: point-like structures such as phantom features, long structures such as metal needles, and fine structures such as trabecular bone structures. Conclusions: Results indicate the feasibility of the proposed algorithm to reduce typical tomosynthesis artifacts produced by high-attenuation features. The proposed algorithm assigns weighting coefficients automatically and no segmentation or tissue-classification steps are required. The algorithm can be included into various iterative reconstruction algorithms with an additive updating strategy. It can also be extended to computed tomography case with the complete set of angular data.

89

Characterization of a constrained paired-view technique in iterative reconstruction for breast tomosynthesis  

International Nuclear Information System (INIS)

Purpose: The order in which the projection views are employed in the reconstruction of tomosynthesis by iterative algorithms, such as simultaneous algebraic reconstruction technique and maximum likelihood, has a strong effect on the rate of convergence, accuracy, and the edge-blurring artifacts in the reconstructed image. The purpose of this investigation was to characterize and evaluate the effects of ordering schemes on image quality for breast tomosynthesis reconstruction and to explore a new constrained paired-view technique that could provide reduction of reconstruction artifacts. In this work, the authors compared several different ordering schemes and characterized the image quality and the formation of out-of-plane artifacts. Furthermore, a new normalization method is presented. It produces more accurate reconstructions with reduced artifacts comparing to the standard method of sequential ordering.Methods: In addition to visual assessment of image quality, several indices such as the signal-difference-to-noise ratio, the artifact-spread function, and the lesion detectability (d?) were computed to quantitatively evaluate the effect of ordering scheme. The sets of breast tomosynthesis projection images were simulated for reconstruction; one set had uniform background (white noise only) and the other two contained both anatomic background and quantum noise. Clinical breast images were also studied for comparison.Results: The authors have quantified the image quality in reconstructed slices for a range of tumor sizes. The authors’ proposed method provides better performance for all of the metrics tested (contrast, d?, and the level of artifacts) both for the uniform phantom case and in the presence of anatomical structure.Conclusions: The paired projection normalization provides better performance in the image quality of the reconstructed slices, and results in a lower level of artifacts in the Z direction. This implies that even a relatively simple method like the “side-to-side” sequence, which pairs two symmetrical projections with equal angular distance from the central projection, would achieve better reconstructed image quality than the conventional “step-by-step” method, which uses sequential projections one after another

90

Characterization of a constrained paired-view technique in iterative reconstruction for breast tomosynthesis  

Energy Technology Data Exchange (ETDEWEB)

Purpose: The order in which the projection views are employed in the reconstruction of tomosynthesis by iterative algorithms, such as simultaneous algebraic reconstruction technique and maximum likelihood, has a strong effect on the rate of convergence, accuracy, and the edge-blurring artifacts in the reconstructed image. The purpose of this investigation was to characterize and evaluate the effects of ordering schemes on image quality for breast tomosynthesis reconstruction and to explore a new constrained paired-view technique that could provide reduction of reconstruction artifacts. In this work, the authors compared several different ordering schemes and characterized the image quality and the formation of out-of-plane artifacts. Furthermore, a new normalization method is presented. It produces more accurate reconstructions with reduced artifacts comparing to the standard method of sequential ordering.Methods: In addition to visual assessment of image quality, several indices such as the signal-difference-to-noise ratio, the artifact-spread function, and the lesion detectability (d{sup ?}) were computed to quantitatively evaluate the effect of ordering scheme. The sets of breast tomosynthesis projection images were simulated for reconstruction; one set had uniform background (white noise only) and the other two contained both anatomic background and quantum noise. Clinical breast images were also studied for comparison.Results: The authors have quantified the image quality in reconstructed slices for a range of tumor sizes. The authors’ proposed method provides better performance for all of the metrics tested (contrast, d{sup ?}, and the level of artifacts) both for the uniform phantom case and in the presence of anatomical structure.Conclusions: The paired projection normalization provides better performance in the image quality of the reconstructed slices, and results in a lower level of artifacts in the Z direction. This implies that even a relatively simple method like the “side-to-side” sequence, which pairs two symmetrical projections with equal angular distance from the central projection, would achieve better reconstructed image quality than the conventional “step-by-step” method, which uses sequential projections one after another.

Wu, Gang; Yaffe, Martin J. [Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada and Sunnybrook Research Institute, S-657, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 Canada (Canada); Mainprize, James G. [Sunnybrook Research Institute, S-657, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada)

2013-10-15

91

A new algorithm for 3D reconstruction from support functions  

DEFF Research Database (Denmark)

We introduce a new algorithm for reconstructing an unknown shape from a finite number of noisy measurements of its support function. The algorithm, based on a least squares procedure, is very easy to program in standard software such as Matlab and allows, for the first time, good 3D reconstructions to be performed on an ordinary PC. Under mild conditions, theory guarantees that outputs of the algorithm will converge to the input shape as the number of measurements increases. Reconstructions may be obtained without any pre- or post-processing steps and with no restriction on the sets of measurement directions except their number, a limitation dictated only by computing time. In addition we offer a linear program version of the new algorithm that is much faster and better, or at least comparable, in performance at low levels of noise and reasonably small numbers of measurements. Another modification of the algorithm, suitable for use in a ``focus of attention'' scheme, is also described.

Gardner, Richard; Kiderlen, Markus

2009-01-01

92

Real-Time Camera Guidance for 3d Scene Reconstruction  

Science.gov (United States)

We propose a framework for operator guidance during the image acquisition process for reliable multi-view stereo reconstruction. Goal is to achieve full coverage of the object and sufficient overlap. Multi-view stereo is a commonly used method to reconstruct both camera trajectory and 3D object shape. After determining an initial solution, a globally optimal reconstruction is usually obtained by executing a bundle adjustment involving all images. Acquiring suitable images, however, still requires an experienced operator to ensure accuracy and completeness of the final solution. We propose an interactive framework for guiding unexperienced users or possibly an autonomous robot. Using approximate camera orientations and object points we estimate point uncertainties within a sliding bundle adjustment and suggest appropriate camera movements. A visual feedback system communicates the decisions to the user in an intuitive way. We demonstrate the suitability of our system with a virtual image acquisition simulation as well as in real-world scenarios. We show that when following the camera movements suggested by our system, the proposed framework is able to generate good approximate values for the bundle adjustment, leading to accurate results compared to ground truth after few iterations. Possible applications are non-professional 3D acquisition systems on low-cost platforms like mobile phones, autonomously navigating robots as well as online flight planning of unmanned aerial vehicles.

Schindler, F.; Förstner, W.

2012-07-01

93

Three-dimensional image reconstruction by digital tomo-synthesis using inverse filtering.  

Science.gov (United States)

Conventional X-ray tomosynthesis with film can provide a sagittal slice image with a single scan. This technique has the advantage of enabling reconstruction of a sagittal slice which is difficult to obtain from the X-ray CT system. However, only an image on the focal plane is obtained by a single scan. Furthermore, the image is degraded by superimpositions of the structures outside of the focal plane. A new three-dimensional image reconstruction method is proposed. This method utilizes a three-dimensional convolution process with an inverse filter function which is derived analytically by the point spread function of the projection and backprojection geometry. A digital tomosynthesis system has also been constructed for the purpose of evaluating the proposed method. This system was used in phantom experiments and clinical evaluations, and it was confirmed that the proposed method was able to reconstruct a better three-dimensional image with less artifacts from outside of the focused slice. PMID:18218419

Matsuo, H; Iwata, A; Horiba, I; Suzumura, N

1993-01-01

94

3D reconstruction of porous electrodes and microstructure modelling  

Energy Technology Data Exchange (ETDEWEB)

The performance of a solid oxide fuel cell (SOFC) is limited by electrode polarisation processes, depending both on material composition and microstructure characteristics. To understand and improve electrode performance, a detailed knowledge of the electrode microstructure is essential. Recent developments in 3D image reconstruction combined with Focused Ion Beam (FIB) and Scanning Electron Microscopy (SEM) techniques proved a way to achieve highly detailed microstructural data. From this data the determination of valuable microstructural parameters is possible. The microstructure is commonly described by parameters as volume/porosity fraction, tortuosity of pores/materal (or: tortuosity of electronic and ionic transport in 2-phase materials), three-phase boundary length (electronic conducting electrodes) or electrode surface area (mixed conducting electrodes). Based on these parameters and with the help of adequate models, the electrode performance can be estimated. It is obvious that the accurateness of the model prediction depends on the quality of the parameters. Different groups reported first trials in the reconstruction of SOFC electrodes by FIB/SEM methods. They all used the reconstruction to calculate microstructural parameters. But nevertheless a lot of questions remain, primarily questions concerning the accuracy of the reconstruction or the minimum size of the volume that has to be reconstructed to obtain meaningful results. In this contribution, a ZEISS 1540XB CrossBeam {sup registered} was used to provide over 700 consecutive images of a porous LSCF (La{sub 0.58}Sr{sub 0.4}CO{sub 0.2.}Fe{sub 0.8}O{sub 3-{delta}})-cathode. The calculation of the key microstructural parameters (i) volume/porosity fraction (ii) electrode surface area and (iii) tortuosity of pores and material from 3D FIB/SEM-data will be presented. Additionally the influence of the reconstruction-volume on the calculated parameters will be discussed. Also the presented technique is applied on a SOFC electrode it constitutes a general method for the 3D characterization of complex multiple-phase materials including battery electrodes. (orig.)

Joos, Jochen; Rueger, Bernd; Weber, Andre; Ivers-Tiffee, Ellen [Karlsruher Institute fuer Technologie (KIT), Karlsruhe (DE). Inst. fuer Werkstoffe der Elektrotechnik (IWE); Carraro, Thomas [Heidelberg Univ. (Germany). Inst. fuer Angewandte Mathematik

2010-07-01

95

Reconstruction of hidden 3D shapes using diffuse reflections.  

Science.gov (United States)

We analyze multi-bounce propagation of light in an unknown hidden volume and demonstrate that the reflected light contains sufficient information to recover the 3D structure of the hidden scene. We formulate the forward and inverse theory of secondary scattering using ideas from energy front propagation and tomography. We show that using Fresnel approximation greatly simplifies this problem and the inversion can be achieved via a backpropagation process. We study the invertibility, uniqueness and choices of space-time-angle dimensions using synthetic examples. We show that a 2D streak camera can be used to discover and reconstruct hidden geometry. Using a 1D high speed time of flight camera, we show that our method can be used recover 3D shapes of objects "around the corner". PMID:23038550

Gupta, Otkrist; Willwacher, Thomas; Velten, Andreas; Veeraraghavan, Ashok; Raskar, Ramesh

2012-08-13

96

GLIMPSE: Accurate 3D weak lensing reconstructions using sparsity  

CERN Document Server

We present GLIMPSE - Gravitational Lensing Inversion and MaPping with Sparse Estimators - a new algorithm to generate density reconstructions in three dimensions from photometric weak lensing measurements. This is an extension of earlier work in one dimension aimed at applying compressive sensing theory to the inversion of gravitational lensing measurements to recover 3D density maps. Using the assumption that the density can be represented sparsely in our chosen basis - 2D transverse wavelets and 1D line of sight dirac functions - we show that clusters of galaxies can be identified and accurately localised and characterised using this method. Throughout, we use simulated data consistent with the quality currently attainable in large surveys. We present a thorough statistical analysis of the errors and biases in both the redshifts of detected structures and their amplitudes. The GLIMPSE method is able to produce reconstructions at significantly higher resolution than the input data; in this paper we show reco...

Leonard, Adrienne; Starck, Jean-Luc

2013-01-01

97

Digital Reconstruction of 3D Polydisperse Dry Foam  

Science.gov (United States)

Dry foam is a disordered packing of bubbles that distort into familiar polyhedral shapes. We have implemented a method that uses optical axial tomography to reconstruct the internal structure of a dry foam in three dimensions. The technique consists of taking a series of photographs of the dry foam against a uniformly illuminated background at successive angles. By summing the projections we create images of the foam cross section. Image analysis of the cross sections allows us to locate Plateau borders and vertices. The vertices are then connected according to Plateau's rules to reconstruct the internal structure of the foam. Using this technique we are able to visualize a large number of bubbles of real 3D foams and obtain statistics of faces and edges.

Chieco, A.; Feitosa, K.; Roth, A. E.; Korda, P. T.; Durian, D. J.

2012-02-01

98

Digital 3D facial reconstruction of George Washington  

Science.gov (United States)

PRISM is a focal point of interdisciplinary research in geometric modeling, computer graphics and visualization at Arizona State University. Many projects in the last ten years have involved laser scanning, geometric modeling and feature extraction from such data as archaeological vessels, bones, human faces, etc. This paper gives a brief overview of a recently completed project on the 3D reconstruction of George Washington (GW). The project brought together forensic anthropologists, digital artists and computer scientists in the 3D digital reconstruction of GW at 57, 45 and 19 including detailed heads and bodies. Although many other scanning projects such as the Michelangelo project have successfully captured fine details via laser scanning, our project took it a step further, i.e. to predict what that individual (in the sculpture) might have looked like both in later and earlier years, specifically the process to account for reverse aging. Our base data was GWs face mask at Morgan Library and Hudons bust of GW at Mount Vernon, both done when GW was 53. Additionally, we scanned the statue at the Capitol in Richmond, VA; various dentures, and other items. Other measurements came from clothing and even portraits of GW. The digital GWs were then milled in high density foam for a studio to complete the work. These will be unveiled at the opening of the new education center at Mt Vernon in fall 2006.

Razdan, Anshuman; Schwartz, Jeff; Tocheri, Mathew; Hansford, Dianne

2006-02-01

99

Digital tomosynthesis of hands using simultaneous algebraic reconstruction technique with distance driven projector  

International Nuclear Information System (INIS)

Digital tomosynthesis (DT) is an X-ray tomographic technique for producing a three-dimensional stack of crosssectional images, based on a limited number of low-dose two-dimensional projections, acquired over a limited angular range. Currently, DT has mainly been investigated for the breast and chest imaging. Another application of DT may be an orthopaedic imaging of hands. A three-dimensional reconstruction with a high in-plane resolution, a low dose and potentially low costs make DT attractive for hand imaging comparing with the planar radiography or computed tomography. However, it should be noted that an accurate image reconstruction in DT is a challenging task due to the high degree of data incompleteness. Images are affected by the residual blur of structures that are located above and below the plane of interest. A human hand consists of 27 bones and therefore the artifact problem becomes even more acute in this case, since the magnitude of artifacts is related not only to the chosen reconstruction type but also to the size and contrast of the artifact-generating object. The study presented in the current work has been performed to show a capability of Simultaneous Algebraic Reconstruction Technique (SART) for hand visualization in tomosynthesis. A distance-driven type for the projector and backprojector operator has been used to make the calculation fast and accurate. Studies have been carried out on a phantom with an uniform background and millimeter-sized balniform background and millimeter-sized balls, a dried finger bone and an in toto hand phantom. A Siemens Mammomat Inspiration device has been used to acquire the projection data. Experimental results show that SART is able to reduce out-of-plane artifacts caused by bone tissue. It provides reconstruction with acceptable quality in only one iteration with the recovered visibility of the obscured trabecular structures as well as the joint spaces and the margins. (orig.)

100

Digital tomosynthesis of hands using simultaneous algebraic reconstruction technique with distance driven projector  

Energy Technology Data Exchange (ETDEWEB)

Digital tomosynthesis (DT) is an X-ray tomographic technique for producing a three-dimensional stack of crosssectional images, based on a limited number of low-dose two-dimensional projections, acquired over a limited angular range. Currently, DT has mainly been investigated for the breast and chest imaging. Another application of DT may be an orthopaedic imaging of hands. A three-dimensional reconstruction with a high in-plane resolution, a low dose and potentially low costs make DT attractive for hand imaging comparing with the planar radiography or computed tomography. However, it should be noted that an accurate image reconstruction in DT is a challenging task due to the high degree of data incompleteness. Images are affected by the residual blur of structures that are located above and below the plane of interest. A human hand consists of 27 bones and therefore the artifact problem becomes even more acute in this case, since the magnitude of artifacts is related not only to the chosen reconstruction type but also to the size and contrast of the artifact-generating object. The study presented in the current work has been performed to show a capability of Simultaneous Algebraic Reconstruction Technique (SART) for hand visualization in tomosynthesis. A distance-driven type for the projector and backprojector operator has been used to make the calculation fast and accurate. Studies have been carried out on a phantom with an uniform background and millimeter-sized balls, a dried finger bone and an in toto hand phantom. A Siemens Mammomat Inspiration device has been used to acquire the projection data. Experimental results show that SART is able to reduce out-of-plane artifacts caused by bone tissue. It provides reconstruction with acceptable quality in only one iteration with the recovered visibility of the obscured trabecular structures as well as the joint spaces and the margins. (orig.)

Levakhina, Y.M. [Luebeck Univ. (Germany). Graduate School for Computing in Medicine and Life Sciences; Luebeck Univ. (Germany). Inst. of Medical Engineering; Duschka, R.L.; Barkhausen, J. [Universitaetsklinikum Schleswig-Holstein, Luebeck (Germany). Klinik fuer Radiologie und Nuklearmedizin; Buzug, T.M. [Luebeck Univ. (Germany). Inst. of Medical Engineering

2011-07-01

 
 
 
 
101

Robust 3D reconstruction with an RGB-D camera.  

Science.gov (United States)

We present a novel 3D reconstruction approach using a low-cost RGB-D camera such as Microsoft Kinect. Compared with previous methods, our scanning system can work well in challenging cases where there are large repeated textures and significant depth missing problems. For robust registration, we propose to utilize both visual and geometry features and combine SFM technique to enhance the robustness of feature matching and camera pose estimation. In addition, a novel prior-based multicandidates RANSAC is introduced to efficiently estimate the model parameters and significantly speed up the camera pose estimation under multiple correspondence candidates. Even when serious depth missing occurs, our method still can successfully register all frames together. Loop closure also can be robustly detected and handled to eliminate the drift problem. The missing geometry can be completed by combining multiview stereo and mesh deformation techniques. A variety of challenging examples demonstrate the effectiveness of the proposed approach. PMID:25203988

Wang, Kangkan; Zhang, Guofeng; Bao, Hujun

2014-11-01

102

3D Lunar Terrain Reconstruction from Apollo Images  

Science.gov (United States)

Generating accurate three dimensional planetary models is becoming increasingly important as NASA plans manned missions to return to the Moon in the next decade. This paper describes a 3D surface reconstruction system called the Ames Stereo Pipeline that is designed to produce such models automatically by processing orbital stereo imagery. We discuss two important core aspects of this system: (1) refinement of satellite station positions and pose estimates through least squares bundle adjustment; and (2) a stochastic plane fitting algorithm that generalizes the Lucas-Kanade method for optimal matching between stereo pair images.. These techniques allow us to automatically produce seamless, highly accurate digital elevation models from multiple stereo image pairs while significantly reducing the influence of image noise. Our technique is demonstrated on a set of 71 high resolution scanned images from the Apollo 15 mission

Broxton, Michael J.; Nefian, Ara V.; Moratto, Zachary; Kim, Taemin; Lundy, Michael; Segal, Alkeksandr V.

2009-01-01

103

Reconstructing 3D radioactive distribution from 2D gamma camera images  

International Nuclear Information System (INIS)

As the development of the nuclear industry, the monitoring and measuring of nuclear facilities and radioactive sources are widely needed. An approach to reconstruct radioactive 3D distribution from 2D ? camera images was proposed. The whole process was divided into two parts: restore ? images to perfect pinhole condition and then using restored image to reconstruct 3D distribution, or namely, image restoration and image reconstruction. According to reconstruction results on simulated and experimental images, proposed radioactive 3D distribution reconstruction scheme worked well. It is possible to acquire accurate radioactive 3D position and intensity distribution based on a few ? camera images using statistical reconstruction method. (author)

104

Experimental PSF modeling for fully 3-D PET reconstruction  

International Nuclear Information System (INIS)

Studies have shown that incorporating measurement-derived point spread functions (PSFs) in reconstruction significantly improves the image quality of positron emission tomography (PET). However, measuring the complete image grids and storing the whole system model are not feasible in practice. We measured the PSFs on a sparse grid and used a parameterization technique to estimate the PSFs at locations that were not measured. Symmetries of the PET scanner and a factorized matrix approach were used to address the storage problem. Our rotator-based algorithm was used to exploit radial symmetries on rectangular voxels. The overall system responses were factorized as a product of a geometric component and a projection space blurring component. The geometric component was also used to determine the axial peak locations of the measured PSFs. An initial implementation of our method was presented, which yielded a compact fully 3-D system model (less than 250 MB). The image quality in terms of resolution (> 1300%) and contrast noise trade-offs (> 15%) was considerably improved compared to the reconstruction of the scanner's standard algorithm. (orig.)

105

Clinical implementation of a digital tomosynthesis-based seed reconstruction algorithm for intraoperative postimplant dose evaluation in low dose rate prostate brachytherapy  

International Nuclear Information System (INIS)

Purpose: The low dose rate brachytherapy procedure would benefit from an intraoperative postimplant dosimetry verification technique to identify possible suboptimal dose coverage and suggest a potential reimplantation. The main objective of this project is to develop an efficient, operator-free, intraoperative seed detection technique using the imaging modalities available in a low dose rate brachytherapy treatment room. Methods: This intraoperative detection allows a complete dosimetry calculation that can be performed right after an I-125 prostate seed implantation, while the patient is still under anesthesia. To accomplish this, a digital tomosynthesis-based algorithm was developed. This automatic filtered reconstruction of the 3D volume requires seven projections acquired over a total angle of 60 deg. with an isocentric imaging system. Results: A phantom study was performed to validate the technique that was used in a retrospective clinical study involving 23 patients. In the patient study, the automatic tomosynthesis-based reconstruction yielded seed detection rates of 96.7% and 2.6% false positives. The seed localization error obtained with a phantom study is 0.4±0.4 mm. The average time needed for reconstruction is below 1 min. The reconstruction algorithm also provides the seed orientation with an uncertainty of 10 deg. ±8 deg. The seed detection algorithm presented here is reliable and was efficiently used in the clinic. Conclusions: When combined with an aic. Conclusions: When combined with an appropriate coregistration technique to identify the organs in the seed coordinate system, this algorithm will offer new possibilities for a next generation of clinical brachytherapy systems.

106

A Comparison of Reconstruction Algorithms Regarding Exposure Dose Reductions during Digital Breast Tomosynthesis  

Directory of Open Access Journals (Sweden)

Full Text Available This study compared reconstruction algorithms [filtered back projection (FBP and simultaneous iterative reconstruction technique (SIRT] with respect to radiation doses and image quality and suggested the possibility of decreasing the exposure dose in digital breast tomosynthesis (DBT. These two existing algorithms were implemented using a DBT system and experimentally evaluated using contrast-detail (CD phantom measurements, such as contrast-to-noise ratio (CNR, root mean square error (RMSE, intensity profile, and artifact spread function (ASF, and the results obtained with FBP and SIRT were compared. The potential dose reduction, contrast improvement, quantum noise reduction, and artifact reduction in DBT were evaluated using different exposures and the two reconstruction techniques. The effectiveness of each technique for enhancing the visibility of a CD phantom was quantified with respect to CNR and RMSE, and artifact reduction was quantified with respect to the intensity profile and ASF. SIRT produced reconstructed images with CNR values indicative of high-contrast detection. Image error was smaller in the in-focus plane SIRT images, and artifacts were decreased in these images according to the determined intensity profiles and ASF. These results suggest that when using SIRT, the exposure dose could possibly be decreased to half.

Tsutomu Gomi

2014-06-01

107

On 3D reconstruction of bubbles in volcanic ash particles  

Science.gov (United States)

Bubbles in volcanic ash particles are primarily represented by the remnants of films and plateau borders from disrupting foam. Without preservation of complete bubbles, measuring bubble size distributions a challenging task, but one for which we have taken a novel approach. Concavities in ash particles retain a record of bubble sizes in the curvature of their concave surfaces that resulted from bubble fragmentation and quenching during energetic magma eruptions. We have used two methods to measure bubble fragment curvature on the basis of 3D reconstruction of ash particle surfaces. One is based on High Resolution X-Ray Tomography (HRXRT) and the second one is based on stereo images from tilting Scattered Electron Microscopy (SEM). Both methods allow the creation of Digital Elevation Model (DEM) datasets of the ash particle surfaces which in turn are used to identify and measure vertical cross-sectional profiles of the individual bubble fragments ("craters"). Function fit analysis for circular or elliptical functions are applied to each bubble cross sectional profile in two orthogonal directions to reconstruct sizes of the original, complete bubbles. The method allows measurement of submicron (SEM; XUM), micron or larger (HRXRT) bubbles in ash particles. The bubble size distributions so obtained can provide valuable insights regarding magma dynamics and vesiculation that lead to explosive eruptions, as well as the processes of fragmentation in eruption columns. There are no previous systematic information/databases of vesiculation metrics for explosive silicic eruptions, but this new method can be used to produce these and thus provide better insights into prehistoric eruption styles for volcanic hazard assessment.

Proussevitch, A.; Sahagian, D.; Mulukutla, G.; Kiely, C.

2007-12-01

108

Image artifacts in digital breast tomosynthesis: Investigation of the effects of system geometry and reconstruction parameters using a linear system approach  

International Nuclear Information System (INIS)

Digital breast tomosynthesis (DBT) is a three-dimensional (3D) x-ray imaging modality that reconstructs image slices parallel to the detector plane. Image acquisition is performed using a limited angular range (less than 50 degrees) and a limited number of projection views (less than 50 views). Due to incomplete data sampling, image artifacts are unavoidable in DBT. In this preliminary study, the image artifacts in DBT were investigated systematically using a linear system approximation. A cascaded linear system model of DBT was developed to calculate the 3D presampling modulation transfer function (MTF) with different image acquisition geometries and reconstruction filters using a filtered backprojection (FBP) algorithm. A thin, slanted tungsten (W) wire was used to measure the presampling MTF of the DBT system in the cross-sectional plane defined by the thickness (z-) and tube travel (x-) directions. The measurement was in excellent agreement with the calculation using the model. A small steel bead was used to calculate the artifact spread function (ASF) of the DBT system. The ASF was correlated with the convolution of the two-dimensional (2D) point spread function (PSF) of the system and the object function of the bead. The results showed that the cascaded linear system model can be used to predict the magnitude of image artifacts of small, high-contrast objects with different image acquisition geometry and reconstruction filters.

109

Effects of point configuration on the accuracy in 3D reconstruction from biplane images  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Two or more angiograms are being used frequently in medical imaging to reconstruct locations in three-dimensional (3D) space, e.g., for reconstruction of 3D vascular trees, implanted electrodes, or patient positioning. A number of techniques have been proposed for this task. In this simulation study, we investigate the effect of the shape of the configuration of the points in 3D (the “cloud” of points) on reconstruction errors for one of these techniques developed in our laboratory. Five ...

Dmochowski, Jacek; Hoffmann, Kenneth R.; Singh, Vikas; Xu, Jinhui; Nazareth, Daryl P.

2005-01-01

110

Comparative Study of Two 3D Reconstruction Methods for Underwater Archaeology  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The underwater 3D reconstruction cartography has made great progress in the last decade. The work presented in this paper is about the analysis and 3D reconstruction of archeological objects. Using a calibrated single camera and an uncalibrated system, we propose to describe a method to perform the Euclidian 3D reconstruction of unknown objects. A comparison of two methods is presented and tested on synthetic and real underwater pictures. Filters are proposed to simulate underwater environmen...

Meline, Arnaud; Triboulet, Jean; Jouvencel, Bruno

2012-01-01

111

Adaptive diffusion regularization for enhancement of microcalcifications in digital breast tomosynthesis (DBT) reconstruction  

Science.gov (United States)

Digital breast tomosynthesis (DBT) has been shown to increase mass detection. Detection of microcalcifications in DBT is challenging because of the small, subtle signals to be searched in the large breast volume and the noise in the reconstructed volume. We developed an adaptive diffusion (AD) regularization method that can differentially regularize noise and potential signal regions during reconstruction based on local contrast-to-noise ratio (CNR) information. This method adaptively applies different degrees of regularity to signal and noise regions, as guided by a CNR map for each DBT slice within the image volume, such that potential signals will be preserved while noise is suppressed. DBT scans of an American College of Radiology phantom and the breast of a subject with biopsy-proven calcifications were acquired with a GE prototype DBT system at 21 angles in 3° increments over a +/-30° range. Simultaneous algebraic reconstruction technique (SART) was used for DBT reconstruction. The AD regularization method was compared to the non-convex total p-variation (TpV) method and SART with no regularization (NR) in terms of the CNR and the full width at half maximum (FWHM) of the central gray-level line profile in the focal plane of a calcification. The results demonstrated that the SART regularized by the AD method enhanced the CNR and preserved the sharpness of microcalcifications compared to reconstruction without regularization. The AD regularization was superior to the TpV method for subtle microcalcifications in terms of the CNR while the FWHM was comparable. The AD regularized reconstruction has the potential to improve the CNR of microcalcifications in DBT for human or machine detection.

Lu, Yao; Chan, Heang-Ping; Fessler, Jeffrey A.; Hadjiiski, Lubomir; Wei, Jun; Goodsitt, Mitchell M.

2011-03-01

112

A diffusion-based truncated projection artifact reduction method for iterative digital breast tomosynthesis reconstruction  

Science.gov (United States)

Digital breast tomosynthesis (DBT) has strong promise to improve sensitivity for detecting breast cancer. DBT reconstruction estimates the breast tissue attenuation using projection views (PVs) acquired in a limited angular range. Because of the limited field of view (FOV) of the detector, the PVs may not completely cover the breast in the x-ray source motion direction at large projection angles. The voxels in the imaged volume cannot be updated when they are outside the FOV, thus causing a discontinuity in intensity across the FOV boundaries in the reconstructed slices, which we refer to as the truncated projection artifact (TPA). Most existing TPA reduction methods were developed for the filtered backprojection method in the context of computed tomography. In this study, we developed a new diffusion-based method to reduce TPAs during DBT reconstruction using the simultaneous algebraic reconstruction technique (SART). Our TPA reduction method compensates for the discontinuity in background intensity outside the FOV of the current PV after each PV updating in SART. The difference in voxel values across the FOV boundary is smoothly diffused to the region beyond the FOV of the current PV. Diffusion-based background intensity estimation is performed iteratively to avoid structured artifacts. The method is applicable to TPA in both the forward and backward directions of the PVs and for any number of iterations during reconstruction. The effectiveness of the new method was evaluated by comparing the visual quality of the reconstructed slices and the measured discontinuities across the TPA with and without artifact correction at various iterations. The results demonstrated that the diffusion-based intensity compensation method reduced the TPA while preserving the detailed tissue structures. The visibility of breast lesions obscured by the TPA was improved after artifact reduction.

Lu, Yao; Chan, Heang-Ping; Wei, Jun; Hadjiiski, Lubomir M.

2013-02-01

113

A diffusion-based truncated projection artifact reduction method for iterative digital breast tomosynthesis reconstruction  

Science.gov (United States)

Digital breast tomosynthesis (DBT) has strong promise to improve sensitivity for detecting breast cancer. DBT reconstruction estimates the breast tissue attenuation using projection views (PVs) acquired in a limited angular range. Because of the limited field of view (FOV) of the detector, the PVs may not completely cover the breast in the x-ray source motion direction at large projection angles. The voxels in the imaged volume cannot be updated when they are outside the FOV, thus causing a discontinuity in intensity across the FOV boundaries in the reconstructed slices, which we refer to as the truncated projection artifact (TPA). Most existing TPA reduction methods were developed for the filtered backprojection method in the context of computed tomography. In this study, we developed a new diffusion-based method to reduce TPAs during DBT reconstruction using the simultaneous algebraic reconstruction technique (SART). Our TPA reduction method compensates for the discontinuity in background intensity outside the FOV of the current PV after each PV updating in SART. The difference in voxel values across the FOV boundary is smoothly diffused to the region beyond the FOV of the current PV. Diffusion-based background intensity estimation is performed iteratively to avoid structured artifacts. The method is applicable to TPA in both the forward and backward directions of the PVs and for any number of iterations during reconstruction. The effectiveness of the new method was evaluated by comparing the visual quality of the reconstructed slices and the measured discontinuities across the TPA with and without artifact correction at various iterations. The results demonstrated that the diffusion-based intensity compensation method reduced the TPA while preserving the detailed tissue structures. The visibility of breast lesions obscured by the TPA was improved after artifact reduction. PMID:23318346

Lu, Yao; Chan, Heang-Ping; Wei, Jun; Hadjiiski, Lubomir M

2014-01-01

114

Reconstruction of quadratic curves in 3-D from two or more perspective views  

Directory of Open Access Journals (Sweden)

Full Text Available The issues involved in the reconstruction of a quadratic curve in 3-D space from arbitrary perspective projections are described in this paper. Correspondence between the projections of the curve on the image planes is assumed to be established. Equations for reconstruction of the 3-D curve, which give the parameters of the 3-D quadratic curve are determined. Uniqueness of the solution in the process of reconstruction is addressed and solved using additional constraints. As practical examples, reconstruction of circles, parabolas and pair of straight lines in 3-D space are demonstrated.

Balasubramanian R.

2002-01-01

115

3D reconstruction method based on time-division multiplexing using multiple depth cameras  

Science.gov (United States)

This article proposes a 3D reconstruction method using multiple depth cameras. Since the depth camera acquires the depth information from a single viewpoint, it's inadequate for 3D reconstruction. In order to solve this problem, we used multiple depth cameras. For 3D scene reconstruction, the depth information is acquired from different viewpoints with multiple depth cameras. However, when using multiple depth cameras, it's difficult to acquire accurate depth information because of interference among depth cameras. To solve this problem, in this research, we propose Time-division multiplexing method. The depth information was acquired from different cameras sequentially. After acquiring the depth images, we extracted features using Fast Point Feature Histogram (FPFH) descriptor. Then, we performed 3D registration with Sample Consensus Initial Alignment (SAC-IA). We reconstructed 3D human bodies with our system and measured body sizes for evaluating the accuracy of 3D reconstruction.

Kang, Ji-Hoon; Lee, Dong-Su; Park, Min-Chul; Lee, Kwang-Hoon

2014-06-01

116

Statistical iterative reconstruction using fast optimization transfer algorithm with successively increasing factor in Digital Breast Tomosynthesis  

Science.gov (United States)

Statistical iterative reconstruction exhibits particularly promising since it provides the flexibility of accurate physical noise modeling and geometric system description in transmission tomography system. However, to solve the objective function is computationally intensive compared to analytical reconstruction methods due to multiple iterations needed for convergence and each iteration involving forward/back-projections by using a complex geometric system model. Optimization transfer (OT) is a general algorithm converting a high dimensional optimization to a parallel 1-D update. OT-based algorithm provides a monotonic convergence and a parallel computing framework but slower convergence rate especially around the global optimal. Based on an indirect estimation on the spectrum of the OT convergence rate matrix, we proposed a successively increasing factor- scaled optimization transfer (OT) algorithm to seek an optimal step size for a faster rate. Compared to a representative OT based method such as separable parabolic surrogate with pre-computed curvature (PC-SPS), our algorithm provides comparable image quality (IQ) with fewer iterations. Each iteration retains a similar computational cost to PC-SPS. The initial experiment with a simulated Digital Breast Tomosynthesis (DBT) system shows that a total 40% computing time is saved by the proposed algorithm. In general, the successively increasing factor-scaled OT exhibits a tremendous potential to be a iterative method with a parallel computation, a monotonic and global convergence with fast rate.

Xu, Shiyu; Zhang, Zhenxi; Chen, Ying

2014-03-01

117

Toward a dose reduction strategy using model-based reconstruction with limited-angle tomosynthesis  

Science.gov (United States)

Model-based iterative reconstruction (MBIR) is an emerging technique for several imaging modalities and appli- cations including medical CT, security CT, PET, and microscopy. Its success derives from an ability to preserve image resolution and perceived diagnostic quality under impressively reduced signal level. MBIR typically uses a cost optimization framework that models system geometry, photon statistics, and prior knowledge of the recon- structed volume. The challenge of tomosynthetic geometries is that the inverse problem becomes more ill-posed due to the limited angles, meaning the volumetric image solution is not uniquely determined by the incom- pletely sampled projection data. Furthermore, low signal level conditions introduce additional challenges due to noise. A fundamental strength of MBIR for limited-views and limited-angle is that it provides a framework for constraining the solution consistent with prior knowledge of expected image characteristics. In this study, we analyze through simulation the capability of MBIR with respect to prior modeling components for limited-views, limited-angle digital breast tomosynthesis (DBT) under low dose conditions. A comparison to ground truth phantoms shows that MBIR with regularization achieves a higher level of fidelity and lower level of blurring and streaking artifacts compared to other state of the art iterative reconstructions, especially for high contrast objects. The benefit of contrast preservation along with less artifacts may lead to detectability improvement of microcalcification for more accurate cancer diagnosis.

Haneda, Eri; Tkaczyk, J. E.; Palma, Giovanni; Iordache, R?zvan; Zelakiewicz, Scott; Muller, Serge; De Man, Bruno

2014-03-01

118

Image reconstruction for digital breast tomosynthesis (DBT) by using projection-angle-dependent filter functions  

Science.gov (United States)

Digital breast tomosynthesis (DBT) is considered in clinics as a standard three-dimensional imaging modality, allowing the earlier detection of cancer. It typically acquires only 10-30 projections over a limited angle range of 15-60° with a stationary detector and typically uses a computationally-efficient filtered-backprojection (FBP) algorithm for image reconstruction. However, a common FBP algorithm yields poor image quality resulting from the loss of average image value and the presence of severe image artifacts due to the elimination of the dc component of the image by the ramp filter and to the incomplete data, respectively. As an alternative, iterative reconstruction methods are often used in DBT to overcome these difficulties, even though they are still computationally expensive. In this study, as a compromise, we considered a projection-angle-dependent filtering method in which one-dimensional geometry-adapted filter kernels are computed with the aid of a conjugate-gradient method and are incorporated into the standard FBP framework. We implemented the proposed algorithm and performed systematic simulation works to investigate the imaging characteristics. Our results indicate that the proposed method is superior to a conventional FBP method for DBT imaging and has a comparable computational cost, while preserving good image homogeneity and edge sharpening with no serious image artifacts.

Park, Yeonok; Park, Chulkyu; Cho, Hyosung; Je, Uikyu; Hong, Daeki; Lee, Minsik; Cho, Heemoon; Choi, Sungil; Koo, Yangseo

2014-09-01

119

Digital breast tomosynthesis geometry calibration  

Science.gov (United States)

Digital Breast Tomosynthesis (DBT) is a 3D x-ray technique for imaging the breast. The x-ray tube, mounted on a gantry, moves in an arc over a limited angular range around the breast while 7-15 images are acquired over a period of a few seconds. A reconstruction algorithm is used to create a 3D volume dataset from the projection images. This procedure reduces the effects of tissue superposition, often responsible for degrading the quality of projection mammograms. This may help improve sensitivity of cancer detection, while reducing the number of false positive results. For DBT, images are acquired at a set of gantry rotation angles. The image reconstruction process requires several geometrical factors associated with image acquisition to be known accurately, however, vibration, encoder inaccuracy, the effects of gravity on the gantry arm and manufacturing tolerances can produce deviations from the desired acquisition geometry. Unlike cone-beam CT, in which a complete dataset is acquired (500+ projections over 180°), tomosynthesis reconstruction is challenging in that the angular range is narrow (typically from 20°-45°) and there are fewer projection images (~7-15). With such a limited dataset, reconstruction is very sensitive to geometric alignment. Uncertainties in factors such as detector tilt, gantry angle, focal spot location, source-detector distance and source-pivot distance can produce several artifacts in the reconstructed volume. To accurately and efficiently calculate the location and angles of orientation of critical components of the system in DBT geometry, a suitable phantom is required. We have designed a calibration phantom for tomosynthesis and developed software for accurate measurement of the geometric parameters of a DBT system. These have been tested both by simulation and experiment. We will present estimates of the precision available with this technique for a prototype DBT system.

Wang, Xinying; Mainprize, James G.; Kempston, Michael P.; Mawdsley, Gordon E.; Yaffe, Martin J.

2007-03-01

120

Methodology for 3D reconstruction of objects for teaching virtual restoration  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, we propose a methodology for 3D virtual reconstruction of objects that can be applied to virtual restoration. The methodology is based on an image-based modelling technique and allows generating a textured 3D mesh from a set of images. The proposed methodology consists in the following actions: obtain images of the object, processing of the images, 3D reconstruction of the object, finishing and completing details, restoration of the 3D virtual model. First, we review several frameworks and toolkits that can be used for image-based modelling and then a detail example of 3D reconstruction is presented. The advantage of this methodology for 3D virtual reconstruction is the use of inexpensive equipment, because only common video and computing devices are needed.

Silviu Butnariu

2013-01-01

 
 
 
 
121

Fully 3D Monte Carlo reconstruction in SPECT: proof of concept and is it worthwhile?  

International Nuclear Information System (INIS)

In Single Photon Emission Computed Tomography (SPECT) with parallel hole collimation, image reconstruction is usually performed as a set of 2D analytical or iterative reconstructions. This approach ignores the 3D nature of scatter and detector response function that affect the detected signal. To deal with the 3D nature of the image formation process, iterative reconstruction can be used by considering a 3D projector modeling the 3D spread of photons. This has already been studied using approximate analytical models for the 3D projector. In this paper, we investigate the value of using accurate Monte Carlo simulations to determine the 3D projector including all physical effects affecting the imaging process (attenuation, scatter, camera point spread function) used in a fully 3D Monte Carlo (F3DMC) reconstruction approach. Given the 3D projector, the reconstruction problem is solved using the maximum likelihood expectation maximization (MLEM) algorithm. To validate the concept, 2 small datasets were simulated and 4 reconstruction strategies were compared: filtered backprojection, MLEM without attenuation correction, MLEM including all corrections with approximate analytical models (MLEMC) and F3DMC. Results suggest that F3DMC multiplies imaging sensitivity by about 103, increases signal-to-noise ratio by 25 to 70% compared to MLEMC and improves spatial resolution. The practical feasibility of the approach on real data sets is discussed. Index Terms - Image reconstruction, Monte Carlo simulations, SPECT. (authors)

122

Quantifying Uncertainties for Prostate Image-Guided Radiotherapy: A 3D Organ Reconstruction and Registration Method  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The purpose of this paper is to present a method for volumetric reconstruction, registration and margin assignation applicable to both conventional CT scans and on board CT imaging. This method does not depend on the shape of the organs, the bony anatomy or the use of markers, and we apply it to prostate and bladder. 3D reconstructions are performed by means of spline surfaces and the 3D reconstructed surfaces are registered to a planning surface, using a multidimensional alignmen...

Gual Arnau, Ximo; Maso?, Rube?n; Lliso, Franc?oise; Lo?pez Tarjuelo, Juan

2009-01-01

123

Enhanced imaging of microcalcifications in digital breast tomosynthesis through improved image-reconstruction algorithms  

CERN Document Server

PURPOSE: We develop a practical, iterative algorithm for image-reconstruction in under-sampled tomographic systems, such as digital breast tomosynthesis (DBT). METHOD: The algorithm controls image regularity by minimizing the image total $p$-variation (TpV), a function that reduces to the total variation when $p=1.0$ or the image roughness when $p=2.0$. Constraints on the image, such as image positivity and estimated projection-data tolerance, are enforced by projection onto convex sets (POCS). The fact that the tomographic system is under-sampled translates to the mathematical property that many widely varied resultant volumes may correspond to a given data tolerance. Thus the application of image regularity serves two purposes: (1) reduction of the number of resultant volumes out of those allowed by fixing the data tolerance, finding the minimum image TpV for fixed data tolerance, and (2) traditional regularization, sacrificing data fidelity for higher image regularity. The present algorithm allows for this...

Sidky, Emil Y; Reiser, Ingrid S; Nishikawa, Robert M; Moore, Richard H; Kopans, Daniel B

2009-01-01

124

Optimized lesion detection in digital breast tomosynthesis  

Science.gov (United States)

While diagnostic improvement via breast tomosynthesis has been notable, the full potential of tomosynthesis has not yet been realized. This is because of the complex task of optimizing multiple parameters that constitute image acquisition and thus affect tomosynthesis performance. Those parameters include dose, number of angular projections, and the total angular span of those projections. In this study, we investigated the effects of acquisition parameters, independent of each other, on the overall diagnostic image quality of tomosynthesis. Five mastectomy specimens were imaged using a prototype tomosynthesis system. 25 angular projections of each specimen were acquired at 6.2 times typical single-view mammographic dose level. Images at lower dose levels were then simulated using a noise modification routine. Each projection image was supplemented with 84 simulated 3 mm 3D lesions embedded at the center of 84 non-overlapping ROIs. The projection images were then reconstructed using a filtered-back projection (FBP) algorithm at 224 different combinations of acquisition parameters to investigate which one of the many possible combinations maximized performance. Performance was evaluated in terms of a Laguerre-Gauss channelized Hotelling observer model-based measure of lesion detectability. Results showed that performance improved with an increase in the total acquisition dose level and the angular span. At a constant dose level and angular span, the performance rolled-off beyond a certain number of projections, indicating that simply increasing the number of projections in tomosynthesis may not necessarily improve its performance. The best performance was obtained with 15-17 projections spanning an angular arc of ~45° - the maximum tested in our study, and for an acquisition dose equal to single-view mammography. The optimization framework developed in this framework is applicable to other reconstruction techniques and other multi-projection systems.

Chawla, Amarpreet S.; Samei, Ehsan; Lo, Joseph Y.

2009-02-01

125

Digital tomosynthesis: technique.  

Science.gov (United States)

Digital breast tomosynthesis is an extension of digital mammography that produces quasi three-dimensional reconstructed images from a set of low-dose x-ray projections acquired over a limited angular range. The quality of the reconstructed image and the dose to the breast are dependent on the angular range and number of projections, the dose used per projection, and detector resolution and noise characteristics. This article discusses various aspects of tomosynthesis optimization. PMID:24792651

Yaffe, Martin J; Mainprize, James G

2014-05-01

126

3D Reconstruction and Visualization of Volume Data in Electrical Capacitance Tomography  

Directory of Open Access Journals (Sweden)

Full Text Available Electrical capacitance tomography (ECT is a non-invasive imaging technique that aims at visualization the permittivity distribution of dielectric materials based on the measured capacitances. In this paper, the 3D finite element models of a direct 3D ECT sensor with or without dielectric spheres inside the sensor are set up by using finite element modeling. The sensitivity analysis of the sensor is carried out by means of electric field intensity. A Landweber iteration method with non-zero threshold is presented to reconstruct 3D permittivity distributions directly. 3D visualization of the reconstructed result (volume data is achieved by iso-surface. 3D images reconstructed and error analysis show that the Landweber iteration method with non-zero threshold has much better reconstruction performance compared with the classic Landweber iteration method.

Hua Yan

2013-10-01

127

A methodology for testing for statistically significant differences between fully 3D PET reconstruction algorithms  

International Nuclear Information System (INIS)

We present a practical methodology for evaluating 3D PET reconstruction methods. It includes generation of random samples from a statistically described ensemble of 3D images resembling those to which PET would be applied in a medical situation, generation of corresponding projection data with noise and detector point spread function simulating those of a 3D PET scanner, assignment of figures of merit appropriate for the intended medical applications, optimization of the reconstruction algorithms on a training set of data, and statistical testing of the validity of hypotheses that say that two reconstruction algorithms perform equally well (from the point of view of a particular figure of merit) as compared to the alternative hypotheses that say that one of the algorithms outperforms the other. Although the methodology was developed with the 3D PET in mind, it can be used, with minor changes, for other 3D data collection methods, such as fully 3D CT or SPECT. (Author)

128

X-ray digital intra-oral tomosynthesis for quasi-three-dimensional imaging: system, reconstruction algorithm, and experiments  

Science.gov (United States)

At present, there are mainly three x-ray imaging modalities for dental clinical diagnosis: radiography, panorama and computed tomography (CT). We develop a new x-ray digital intra-oral tomosynthesis (IDT) system for quasi-three-dimensional dental imaging which can be seen as an intermediate modality between traditional radiography and CT. In addition to normal x-ray tube and digital sensor used in intra-oral radiography, IDT has a specially designed mechanical device to complete the tomosynthesis data acquisition. During the scanning, the measurement geometry is such that the sensor is stationary inside the patient's mouth and the x-ray tube moves along an arc trajectory with respect to the intra-oral sensor. Therefore, the projection geometry can be obtained without any other reference objects, which makes it be easily accepted in clinical applications. We also present a compressed sensing-based iterative reconstruction algorithm for this kind of intra-oral tomosynthesis. Finally, simulation and experiment were both carried out to evaluate this intra-oral imaging modality and algorithm. The results show that IDT has its potentiality to become a new tool for dental clinical diagnosis.

Li, Liang; Chen, Zhiqiang; Zhao, Ziran; Wu, Dufan

2013-01-01

129

3-D Virtual and Physical Reconstruction of Bendego Iron  

Science.gov (United States)

The use of 3D laser scanning to meteoritic to preserve the original shape of the meteorites before cutting and the facility of saved the datas in STL format (stereolithography) to print three-dimensional physical models and generate a digital replica.

Belmonte, S. L. R.; Zucolotto, M. E.; Fontes, R. C.; dos Santos, J. R. L.

2012-09-01

130

Cone-Convolution method for directly image reconstruction of cone-beam 3-D CT system  

International Nuclear Information System (INIS)

The theories and methods of directly 3-D image reconstruction from projections for 3-D CT system are the international front end research projects of modern CT technology. For the single circle source cone-beam 3-D CT system, which has both advantages in structure and disadvantages in incomplete projection data, a new 3-D direct image reconstruction method called 'Cone-Convolution' has been developed. The computer simulation shows that the new method can get much better result than traditional method. The fundamentals of the Cone-Convolution method, the approach steps and some related computer simulation results are expressed

131

RECONSTRUCCIÓN DE OBJETO 3D A PARTIR DE IMÁGENES CALIBRADAS 3D OBJECT RECONSTRUCTION WITH CALIBRATED IMAGES  

Directory of Open Access Journals (Sweden)

Full Text Available Este trabajo presenta el desarrollo de un sistema de reconstrucción de objeto 3D, a partir de una colección de vistas. El sistema se compone de dos módulos principales. El primero realiza el procesamiento de imagen, cuyo objetivo es determinar el mapa de profundidad en un par de vistas, donde cada par de vistas sucesivas sigue una secuencia de fases: detección de puntos de interés, correspondencia de puntos y reconstrucción de puntos; en el proceso de reconstrucción se determinan los parámetros que describen el movimiento (matriz de rotación R y el vector de traslación T entre las dos vistas. Esta secuencia de pasos se repite para todos los pares de vista sucesivas del conjunto. El segundo módulo tiene como objetivo crear el modelo 3D del objeto, para lo cual debe determinar el mapa total de todos los puntos 3D generados; en cada iteración del módulo anterior, una vez obtenido el mapa de profundidad total, genera la malla 3D, aplicando el método de triangulación de Delaunay [28]. Los resultados obtenidos del proceso de reconstrucción son modelados en un ambiente virtual VRML para obtener una visualización más realista del objeto.The system is composed of two main modules. The first one, carries out the image prosecution, whose objective is to determine the depth map of a pair of views where each pair of successive views continues a sequence of phases: interest points detection, points correspondence and points reconstruction; in the reconstruction process, is determined the parameters that describe the movement (rotation matrix R and the translation vector T between the two views. This an sequence of steps is repeated for all the peers of successive views of the set. The second module has as objective to create the 3D model of the object, for it should determine the total map of all the 3D points generated, by each iteration of the previous module, once obtained the map of total depth generates the 3D netting, applying the triangulation method of Delaunay [28]. The results obtained of the reconstruction process are shaped in a VRML virtual environment, to obtain a viewing more realist of the object.

Natividad Grandón-Pastén

2007-08-01

132

3D Tomographic Image Reconstruction using CUDA C  

International Nuclear Information System (INIS)

This paper presents the study and implementation of a software for three dimensional reconstruction of images obtained with a tomographic system using the capabilities of Graphic Processing Units(GPU). The reconstruction by filtered back-projection method was developed using the CUDA C, for maximum utilization of the processing capabilities of GPUs to solve computational problems with large computational cost and highly parallelizable. It was discussed the potential of GPUs and shown its advantages to solving this kind of problems. The results in terms of runtime will be compared with non-parallelized implementations and must show a great reduction of processing time. (Author)

133

3D Reconstruction of SPM Probes by Electron Tomography  

International Nuclear Information System (INIS)

Three-dimensional morphological and compositional structures of tungsten tips consisting of layered amorphous oxide shell and crystalline W core are reconstructed by electron tomography using both coherent and incoherent imaging modes. The fidelity of the reconstruction is dependent on three criteria, suppression of unwanted crystal orientation contrast in the crystalline core, nonlinear intensity-thickness relations above a certain thickness limit, and artefacts due to missing angular ranges when acquiring a tilt series of images. Annular dark field (ADF), and EDX chemical mapping are discussed as alternatives to standard bright field (BF) TEM imaging

134

An efficient Fourier method for 3-D radon inversion in exact cone-beam CT reconstruction.  

Science.gov (United States)

The radial derivative of the three-dimensional (3-D) radon transform of an object is an important intermediate result in many analytically exact cone-beam reconstruction algorithms. We briefly review Grangeat's approach for calculating radon derivative data from cone-beam projections and then present a new, efficient method for 3-D radon inversion, i.e., reconstruction of the image from the radial derivative of the 3-D radon transform, called direct Fourier inversion (DFI). The method is based directly on the 3-D Fourier slice theorem. From the 3-D radon derivative data, which is assumed to be sampled on a spherical grid, the 3-D Fourier transform of the object is calculated by performing fast Fourier transforms (FFT's) along radial lines in the radon space. Then, an interpolation is performed from the spherical to a Cartesian grid using a 3-D gridding step in the frequency domain. Finally, this 3-D Fourier transform is transformed back to the spatial domain via 3-D inverse FFT. The algorithm is computationally efficient with complexity in the order of N3 logN. We have done reconstructions of simulated 3-D radon derivative data assuming sampling conditions and image quality requirements similar to those in medical computed tomography (CT). PMID:9688156

Schaller, S; Flohr, T; Steffen, P

1998-04-01

135

The clinical application of 3D CT reconstruction technique in bone tumor  

International Nuclear Information System (INIS)

Objective: To evaluate the clinical application of 3D CT reconstruction technique in bone tumor. Methods: In total 20 cases with bone tumor were scanned in 2-3 mm collimation and at pitch of 1 using Toshiba Xpress/SX CT scanner. After the scan was completed, 3D reconstruction including SSD and MPR was performed at Sun Sparc station 20 workstation with software Toshiba Xtension 2.01. Results: Quality 3D images were obtained in all 20 cases. The stereoscopy of the tumor and surrounding anatomical structure was well demonstrated in 3D images. Conclusion: Besides axial images, the 3D CT reconstruction including SSD and MPR provides extra information, and helps the qualitative diagnosis of bone tumor. (authors)

136

Combinatorial clustering and Its Application to 3D Polygonal Traffic Sign Reconstruction From Multiple Images  

Science.gov (United States)

The 3D reconstruction of similar 3D objects detected in 2D faces a major issue when it comes to grouping the 2D detections into clusters to be used to reconstruct the individual 3D objects. Simple clustering heuristics fail as soon as similar objects are close. This paper formulates a framework to use the geometric quality of the reconstruction as a hint to do a proper clustering. We present a methodology to solve the resulting combinatorial optimization problem with some simplifications and approximations in order to make it tractable. The proposed method is applied to the reconstruction of 3D traffic signs from their 2D detections to demonstrate its capacity to solve ambiguities.

Vallet, B.; Soheilian, B.; Brédif, M.

2014-08-01

137

Multi-view 3D circular target reconstruction with uncertainty analysis  

Science.gov (United States)

The paper presents an algorithm for reconstruction of 3D circle from its apparition in n images. It supposes that camera poses are known up to an uncertainty. They will be considered as observations and will be refined during the reconstruction process. First, circle apparitions will be estimated in every individual image from a set of 2D points using a constrained optimization. Uncertainty of 2D points are propagated in 2D ellipse estimation and leads to covariance matrix of ellipse parameters. In 3D reconstruction process ellipse and camera pose parameters are considered as observations with known covariances. A minimal parametrization of 3D circle enables to model the projection of circle in image without any constraint. The reconstruction is performed by minimizing the length of observation residuals vector in a non linear Gauss-Helmert model. The output consists in parameters of the corresponding circle in 3D and their covariances. The results are presented on simulated data.

Soheilian, B.; Brédif, M.

2014-08-01

138

RECONSTRUCCIÓN DE OBJETO 3D A PARTIR DE IMÁGENES CALIBRADAS / 3D OBJECT RECONSTRUCTION WITH CALIBRATED IMAGES  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: Spanish Abstract in spanish Este trabajo presenta el desarrollo de un sistema de reconstrucción de objeto 3D, a partir de una colección de vistas. El sistema se compone de dos módulos principales. El primero realiza el procesamiento de imagen, cuyo objetivo es determinar el mapa de profundidad en un par de vistas, donde cada p [...] ar de vistas sucesivas sigue una secuencia de fases: detección de puntos de interés, correspondencia de puntos y reconstrucción de puntos; en el proceso de reconstrucción se determinan los parámetros que describen el movimiento (matriz de rotación R y el vector de traslación T) entre las dos vistas. Esta secuencia de pasos se repite para todos los pares de vista sucesivas del conjunto. El segundo módulo tiene como objetivo crear el modelo 3D del objeto, para lo cual debe determinar el mapa total de todos los puntos 3D generados; en cada iteración del módulo anterior, una vez obtenido el mapa de profundidad total, genera la malla 3D, aplicando el método de triangulación de Delaunay [28]. Los resultados obtenidos del proceso de reconstrucción son modelados en un ambiente virtual VRML para obtener una visualización más realista del objeto. Abstract in english The system is composed of two main modules. The first one, carries out the image prosecution, whose objective is to determine the depth map of a pair of views where each pair of successive views continues a sequence of phases: interest points detection, points correspondence and points reconstructio [...] n; in the reconstruction process, is determined the parameters that describe the movement (rotation matrix R and the translation vector T) between the two views. This an sequence of steps is repeated for all the peers of successive views of the set. The second module has as objective to create the 3D model of the object, for it should determine the total map of all the 3D points generated, by each iteration of the previous module, once obtained the map of total depth generates the 3D netting, applying the triangulation method of Delaunay [28]. The results obtained of the reconstruction process are shaped in a VRML virtual environment, to obtain a viewing more realist of the object.

Natividad, Grandón-Pastén; Diego, Aracena-Pizarro; Clésio Luis, Tozzi.

2007-08-01

139

Appearance of bony lesions on 3-D CT reconstructions: a case study in variable renderings  

Science.gov (United States)

This paper discusses conventional 3-D reconstruction for bone visualization and presents a case study to demonstrate the dangers of performing 3-D reconstructions without careful selection of the bone threshold. The visualization of midface bone lesions directly from axial CT images is difficult because of the complex anatomic relationships. Three-dimensional reconstructions made from the CT to provide graphic images showing lesions in relation to adjacent facial bones. Most commercially available 3-D image reconstruction requires that the radiologist or technologist identify a threshold image intensity value that can be used to distinguish bone from other tissues. Much has been made of the many disadvantages of this technique, but it continues as the predominant method in producing 3-D pictures for clinical use. This paper is intended to provide a clear demonstration for the physician of the caveats that should accompany 3-D reconstructions. We present a case of recurrent odontogenic keratocyst in the anterior maxilla where the 3-D reconstructions, made with different bone thresholds (windows), are compared to the resected specimen. A DMI 3200 computer was used to convert the scan data from a GE 9800 CT into a 3-D shaded surface image. Threshold values were assigned to (1) generate the most clinically pleasing image, (2) produce maximum theoretical fidelity (using the midpoint image intensity between average cortical bone and average soft tissue), and (3) cover stepped threshold intensities between these two methods. We compared the computer lesions with the resected specimen and noted measurement errors of up to 44 percent introduced by inappropriate bone threshold levels. We suggest clinically applicable standardization techniques in the 3-D reconstruction as well as cautionary language that should accompany the 3-D images.

Mankovich, Nicholas J.; White, Stuart C.

1992-05-01

140

3D reconstruction of the hemocyanin subunit dimer from the chiton Acanthochiton fascicularis.  

Science.gov (United States)

Procedures are presented for the purification of the subunit dimer from Acanthochiton fasicularis hemocyanin. Electron microscopy of negatively stained specimens revealed a uniform population of macromolecules possessing the characteristic "boat shape". A 3D reconstruction from this EM data generated a approximately 3 nm resolution model that correlates well with earlier data of the purported subunit dimer, extracted from the 3D reconstruction of the didecamer of Haliotis tuberculata hemocyanin type 1. PMID:15036283

Harris, J Robin; Meissner, Ulrich; Gebauer, Wolfgang; Markl, Jürgen

2004-01-01

 
 
 
 
141

Automated Reconstruction Algorithm for Identification of 3D Architectures of Cribriform Ductal Carcinoma In Situ  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Ductal carcinoma in situ (DCIS) is a pre-invasive carcinoma of the breast that exhibits several distinct morphologies but the link between morphology and patient outcome is not clear. We hypothesize that different mechanisms of growth may still result in similar 2D morphologies, which may look different in 3D. To elucidate the connection between growth and 3D morphology, we reconstruct the 3D architecture of cribriform DCIS from resected patient material. We produce a fully automated algorith...

Norton, Kerri-ann; Namazi, Sameera; Barnard, Nicola; Fujibayashi, Mariko; Bhanot, Gyan; Ganesan, Shridar; Iyatomi, Hitoshi; Ogawa, Koichi; Shinbrot, Troy

2012-01-01

142

Autonomous Planetary 3-D Reconstruction From Satellite Images  

DEFF Research Database (Denmark)

A common task for many deep space missions is autonomous generation of 3-D representations of planetary surfaces onboard unmanned spacecrafts. The basic problem for this class of missions is, that the closed loop time is far too long. The closed loop time is defined as the time from when a human operator detects an interesting object or feature on a, say, asteroid, to a command is issued to aim a science instrument at the feature. This delay may be in the range of hours for all except the objects closest to the Earth. Because the transit time of a typical interesting feature is in the range of seconds to a few minutes, the closed loop time effectively precludes active human control.The only way to circumvent this problem is to build an artificial feature extractor operating autonomously onboard the spacecraft.Different artificial feature extractors are presented and their efficiency is discussed.Based on such features, 3-D representations may be compiled from two or more 2-D satellite images. The main purposes of such a mapping system are extraction of landing sites, objects of scientific interest and general planetary surveying. All data processing is performed autonomously onboard in order to reduce data transfer to ground station and to eliminate the closed loop time delay.

Denver, Troelz

1999-01-01

143

Sound-speed image reconstruction in sparse-aperture 3-D ultrasound transmission tomography.  

Science.gov (United States)

The paper is focused on sound-speed image reconstruction in 3-D ultrasound transmission tomography. Along with ultrasound reflectivity and the attenuation coefficient, sound speed is an important parameter which is related to the type and pathological state of the imaged tissue. This is important in the intended application, breast cancer diagnosis. In contrast to 2-D ultrasound transmission tomography systems, a 3-D system can provide an isotropic spatial resolution in the x-, y-, and z-directions in reconstructed 3-D images of ultrasound parameters. Several challenges must, however, be addressed for 3-D systems-namely, a sparse transducer distribution, low signal-to-noise ratio, and higher computational complexity. These issues are addressed in terms of sound-speed image reconstruction, using edge-preserving regularized algebraic reconstruction in combination with synthetic aperture focusing. The critical points of the implementation are also discussed, because they are crucial to enable a complete 3-D image reconstruction. The methods were tested on a synthetic data set and on data sets measured with the Karlsruhe 3-D ultrasound computer tomography (USCT) I prototype using phantoms. The sound-speed estimates in the reconstructed volumes agreed with the reference values. The breast-phantom outlines and the lesion-mimicking objects were also detectable in the resulting sound-speed volumes. PMID:24626033

Jirík, Radovan; Peterlík, Igor; Ruiter, Nicole; Fousek, Jan; Dapp, Robin; Zapf, Michael; Jan, Jirí

2012-02-01

144

3D Fractal reconstruction of terrain profile data based on digital elevation model  

International Nuclear Information System (INIS)

Digital Elevation Model (DEM) often makes it difficult for terrain reconstruction and data storage due to the failure in acquisition of details with higher resolution. If original terrain of DEM can be simulated, resulting in geographical details can be represented precisely while reducing the data size, then an effective reconstruction scheme is essential. This paper adopts two sets of real-world 3D terrain profile data to proceed data reducing, i.e. data sampling randomly, then reconstruct them through 3D fractal reconstruction. Meanwhile, the quantitative and qualitative difference generated from different reduction rates were evaluated statistically. The research results show that, if 3D fractal interpolation method is applied to DEM reconstruction, the higher reduction rate can be obtained for DEM of larger data size with respect to that of smaller data size under the assumption that the entire terrain structure is still maintained.

145

Fully 3D Monte Carlo image reconstruction in SPECT using functional regions  

CERN Document Server

Image reconstruction in Single Photon Emission Computed Tomography (SPECT) is affected by physical effects such as photon attenuation, Compton scatter and detector response. These effects can be compensated for by modeling the corresponding spread of photons in 3D within the system matrix used for tomographic reconstruction. The fully 3D Monte Carlo (F3DMC) reconstruction technique consists in calculating this system matrix using Monte Carlo simulations. The inverse problem of tomographic reconstruction is then solved using conventional iterative algorithms such as maximum likelihood expectation maximization (MLEM). Although F3DMC has already shown promising results, its use is currently limited by two major issues: huge size of the fully 3D system matrix and long computation time required for calculating a robust and accurate system matrix. To address these two issues, we propose to calculate the F3DMC system matrix using a spatial sampling matching the functional regions to be reconstructed. In this approac...

Bitar, Z E; Coello, C; Breton, V; Hill, D; Buvat, I

2006-01-01

146

Assessing 3D tunnel position in ACL reconstruction using a novel single image 3D-2D registration  

Science.gov (United States)

The routinely used procedure for evaluating tunnel positions following anterior cruciate ligament (ACL) reconstructions based on standard X-ray images is known to pose difficulties in terms of obtaining accurate measures, especially in providing three-dimensional tunnel positions. This is largely due to the variability in individual knee joint pose relative to X-ray plates. Accurate results were reported using postoperative CT. However, its extensive usage in clinical routine is hampered by its major requirement of having CT scans of individual patients, which is not available for most ACL reconstructions. These difficulties are addressed through the proposed method, which aligns a knee model to X-ray images using our novel single-image 3D-2D registration method and then estimates the 3D tunnel position. In the proposed method, the alignment is achieved by using a novel contour-based 3D-2D registration method wherein image contours are treated as a set of oriented points. However, instead of using some form of orientation weighting function and multiplying it with a distance function, we formulate the 3D-2D registration as a probability density estimation using a mixture of von Mises-Fisher-Gaussian (vMFG) distributions and solve it through an expectation maximization (EM) algorithm. Compared with the ground-truth established from postoperative CT, our registration method in an experiment using a plastic phantom showed accurate results with errors of (-0.43°+/-1.19°, 0.45°+/-2.17°, 0.23°+/-1.05°) and (0.03+/-0.55, -0.03+/-0.54, -2.73+/-1.64) mm. As for the entry point of the ACL tunnel, one of the key measurements, it was obtained with high accuracy of 0.53+/-0.30 mm distance errors.

Kang, X.; Yau, W. P.; Otake, Y.; Cheung, P. Y. S.; Hu, Y.; Taylor, R. H.

2012-02-01

147

Selective-diffusion regularization for enhancement of microcalcifications in digital breast tomosynthesis reconstruction  

Energy Technology Data Exchange (ETDEWEB)

Purpose: Digital breast tomosynthesis (DBT) has been shown to improve mass detection. Detection of microcalcifications is more challenging because of the large breast volume to be searched for subtle signals. The simultaneous algebraic reconstruction technique (SART) was found to provide good image quality for DBT, but the image noise is amplified with an increasing number of iterations. In this study, the authors developed a selective-diffusion (SD) method for noise regularization with SART to improve the contrast-to-noise ratio (CNR) of microcalcifications in the DBT slices for human or machine detection. Methods: The SD method regularizes SART reconstruction during updating with each projection view. Potential microcalcifications are differentiated from the noisy background by estimating the local gradient information. Different degrees of regularization are applied to the signal or noise classes, such that the microcalcifications will be enhanced while the noise is suppressed. The new SD method was compared to several current methods, including the quadratic Laplacian (QL) method, the total variation (TV) method, and the nonconvex total p-variation (TpV) method for noise regularization with SART. A GE GEN2 prototype DBT system with a stationary digital detector was used for the acquisition of DBT scans at 21 angles in 3 deg. increments over a {+-}30 deg. range. The reconstruction image quality without regularization and that with the different regularization methods were compared using the DBT scans of an American College of Radiology phantom and a human subject. The CNR and the full width at half maximum (FWHM) of the line profiles of microcalcifications within the in-focus DBT slices were used as image quality measures. Results: For the comparison of large microcalcifications in the DBT data of the subject, the SD method resulted in comparable CNR to the nonconvex TpV method. Both of them performed better than the other two methods. For subtle microcalcifications, the SD method was superior to other methods in terms of CNR. In both the subject and phantom DBT data, for large microcalcifications, the FWHM of the SD method was comparable to that without regularization, which was wider than that of the TV type methods. For subtle microcalcifications, the SD method had comparable FWHM values to the TV type methods. All three regularization methods were superior to the QL method in terms of FWHM. Conclusions: The SART regularized by the selective-diffusion method enhanced the CNR and preserved the sharpness of microcalcifications. In comparison with three existing regularization methods, the selective-diffusion regularization was superior to the other methods for subtle microcalcifications.

Lu Yao; Chan, Heang-Ping; Wei Jun; Hadjiiski, Lubomir M. [Department of Radiology, University of Michigan, Ann Arbor, Michigan 48109 (United States)

2010-11-15

148

Preoperative Planning Using 3D Reconstructions and Virtual Endoscopy for Location of the Frontal Sinus  

Directory of Open Access Journals (Sweden)

Full Text Available Introduction: Computed tomography (TC generated tridimensional (3D reconstructions allow the observation of cavities and anatomic structures of our body with detail. In our specialty there have been attempts to carry out virtual endoscopies and laryngoscopies. However, such application has been practically abandoned due to its complexity and need for computers with high power of graphic processing. Objective: To demonstrate the production of 3D reconstructions from CTs of patients in personal computers, with a free specific program and compare them to the surgery actual endoscopic images. Method: Prospective study in which the CTs proper files of 10 patients were reconstructed with the program Intage Realia, version 2009, 0, 0, 702 (KGT Inc., Japan. The reconstructions were carried out before the surgeries and a virtual endoscopy was made to assess the recess and frontal sinus region. After this study, the surgery was digitally performed and stored. The actual endoscopic images of the recess and frontal sinus region were compared to the virtual images. Results: The 3D reconstruction and virtual endoscopy were made in 10 patients submitted to the surgery. The virtual images had a large resemblance with the actual surgical images. Conclusion: With relatively simple tools and personal computer, we demonstrated the possibility to generate 3D reconstructions and virtual endoscopies. The preoperative knowledge of the frontal sinus natural draining path location may generate benefits during the performance of surgeries. However, more studies must be developed for the evaluation of the real roles of such 3D reconstructions and virtual endoscopies.

Abreu, João Paulo Saraiva

2011-01-01

149

Digital Holographic Capture and Optoelectronic Reconstruction for 3D Displays  

Directory of Open Access Journals (Sweden)

Full Text Available The application of digital holography as a viable solution to 3D capture and display technology is examined. A review of the current state of the field is presented in which some of the major challenges involved in a digital holographic solution are highlighted. These challenges include (i the removal of the DC and conjugate image terms, which are features of the holographic recording process, (ii the reduction of speckle noise, a characteristic of a coherent imaging process, (iii increasing the angular range of perspective of digital holograms (iv and replaying captured and/or processed digital holograms using spatial light modulators. Each of these challenges are examined theoretically and several solutions are put forward. Experimental results are presented that demonstrate the validity of the theoretical solutions.

Malgorzata Kujawinska

2010-01-01

150

Reconstruction of 3D morphology of polyhedral nanoparticles  

Energy Technology Data Exchange (ETDEWEB)

The three-dimensional (3D) faceting morphology of ceria nanoparticles is analysed using transmission electron microscopy (TEM)-based computed tomography on the nanometre scale. A novel tomography mode of electron energy loss spectroscopic imaging using a single energy window for inelastically scattered electrons is introduced and found to be reliable and fast for freestanding nanoparticles. To compare the new tomographic method with other methods, we provide the first comprehensive application of three complementary TEM-based imaging techniques, including bright field TEM and annular dark field specific TEM (STEM). Traditional bright-field TEM tomography is found to be applicable, in spite of obvious artefacts, for crystalline particles of constant composition. However, the safest interpretation is achieved by a combined recording of bright field and spectroscopic images.

Xu Xiaojing; Saghi, Zineb; Gay, Ralph; Moebus, Guenter [Department of Engineering Materials, University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom)

2007-06-06

151

Reconstruction of 3D morphology of polyhedral nanoparticles  

International Nuclear Information System (INIS)

The three-dimensional (3D) faceting morphology of ceria nanoparticles is analysed using transmission electron microscopy (TEM)-based computed tomography on the nanometre scale. A novel tomography mode of electron energy loss spectroscopic imaging using a single energy window for inelastically scattered electrons is introduced and found to be reliable and fast for freestanding nanoparticles. To compare the new tomographic method with other methods, we provide the first comprehensive application of three complementary TEM-based imaging techniques, including bright field TEM and annular dark field specific TEM (STEM). Traditional bright-field TEM tomography is found to be applicable, in spite of obvious artefacts, for crystalline particles of constant composition. However, the safest interpretation is achieved by a combined recording of bright field and spectroscopic images

152

3D waveguides reconstruction with SDO/HMI magnetograms  

Science.gov (United States)

We developed a new method for obtain 3D height-spatial structure of magnetic tubes over sunspot atmosphere. The method based on dynamics of extrapolated magnetic surfaces (SDO/HMI magnetograms) and PWF technique. We calculate the 3D position of magnetic channels for active region NOAA 11131 on December 08, 2010 event. These structures can be interpreted as waveguides (magnetic bundles) that channel upward propagating slow MHD waves, responsible for 3-min oscillation. The footpoints of tubes anchored at under-photosphere level. Location of bundles individual for each sunspot. The bundles shows a cone-like structure with symmetrical base at the bottom (photosphere) and ring-like shape at upper level (transition region). Depend from bundles location inside umbra we can see different lines inclination: in center mainly there are open lines; near the umbra border there are mix of open and close lines with different inclination. Magnetic lines inclination are increasing to umbra/penumbra border. The shape of narrowband 3-min oscillation sources at photosphere level has a symmetrical circular structure and fill whole umbra up to its borders. At chromosphere and transition region helical twist of propagating 3-min wave fronts with their scattering on the umbra-penumbra boundary is observed. The wave sources is localized in the center of the sunspot umbra as a pulsating bright areas of small angular size. At the coronal level there are both expending symmetrical fronts and elongated structures located in the penumbra area coinciding with footpoints of magnetic field tubes with individual frequency behavior. To explain obtained results we can suggest about dependence between waves visibility and existing two effects: the cut-off frequency and direction magnetic lines in LOS to observer. We can conclude that observed quasi-helicity connected with interaction of magnetic bundles with different spatial localization, magnetic lines inclination and cut-off frequency effect.

Sych, Robert; Wang, Rui

153

Neurofunctional systems. 3D reconstructions with correlated neuroimaging  

International Nuclear Information System (INIS)

This book introduces, for the first time, computer-generated images of the neurofunctional systems of the human brain. These images are more accurate than drawings. The main views presented are of the medial lemniscus system, auditory system, visual system, basal ganglia, corticospinal system, and the limbic system. The arteries and sulci of the cerebral hemispheres are also illustrated by computer. These images provide a three-dimensional orientation of the intracranial space and help, for example, to assess vascular functional disturbance of the brain. Clinicians will find these images valuable for the spatial interpretation of magnetic resonance (MR), computed tomography (CT), and positron emission tomography (PET) images since many neurofunctional systems cannot be visualized as isolated structures in neuroimaging. Computer-assisted surface reconstructions of the neurofunctional systems and the cerebral arteries serve as a basis for constructing these computer-generated images. The surface reconstructions are anatomically realistic having been created from brain sections with minimal deformations. The method of computer graphics, known as ray tracing, produces digital images form these reconstructions. The computer-generated methods are explained. The computer-generated images are accompanied by illustrations and texts on neuroanatomy and clinical practice. The neurofunctional systems of the human brain are also shown in sections so that the reader can mentally reections so that the reader can mentally reconstruct the neurofunctional systems, thus facilitating the transformation of information into textbooks and atlantes of MR and CT imaging. The aim of this book is acquaint the reader with the three-dimensional aspects of the neurofunctional systems and the cerebral arteries of the human brain using methods of computer graphics. Computer scientists and those interested in this technique are provided with basic neuroanatomic and neurofunctional information. Physicians will have a clearer understanding of the limitations and possibilities of computer graphics in the field of medicine. The three-dimensional aspects of these neurofunctional systems should serve as a tool for clinicians and will appeal to neurologists, neurosurgeons, neuroradiologists, nuclear physicians, neurophysiologists, traumatologists and oncologists. Physicians and students with an interest in neurobiology will also find this an instructive and practical handbook. (orig.)

154

Neurofunctional systems. 3D reconstructions with correlated neuroimaging  

Energy Technology Data Exchange (ETDEWEB)

This book introduces, for the first time, computer-generated images of the neurofunctional systems of the human brain. These images are more accurate than drawings. The main views presented are of the medial lemniscus system, auditory system, visual system, basal ganglia, corticospinal system, and the limbic system. The arteries and sulci of the cerebral hemispheres are also illustrated by computer. These images provide a three-dimensional orientation of the intracranial space and help, for example, to assess vascular functional disturbance of the brain. Clinicians will find these images valuable for the spatial interpretation of magnetic resonance (MR), computed tomography (CT), and positron emission tomography (PET) images since many neurofunctional systems cannot be visualized as isolated structures in neuroimaging. Computer-assisted surface reconstructions of the neurofunctional systems and the cerebral arteries serve as a basis for constructing these computer-generated images. The surface reconstructions are anatomically realistic having been created from brain sections with minimal deformations. The method of computer graphics, known as ray tracing, produces digital images form these reconstructions. The computer-generated methods are explained. The computer-generated images are accompanied by illustrations and texts on neuroanatomy and clinical practice. The neurofunctional systems of the human brain are also shown in sections so that the reader can mentally reconstruct the neurofunctional systems, thus facilitating the transformation of information into textbooks and atlantes of MR and CT imaging. The aim of this book is acquaint the reader with the three-dimensional aspects of the neurofunctional systems and the cerebral arteries of the human brain using methods of computer graphics. Computer scientists and those interested in this technique are provided with basic neuroanatomic and neurofunctional information. Physicians will have a clearer understanding of the limitations and possibilities of computer graphics in the field of medicine. The three-dimensional aspects of these neurofunctional systems should serve as a tool for clinicians and will appeal to neurologists, neurosurgeons, neuroradiologists, nuclear physicians, neurophysiologists, traumatologists and oncologists. Physicians and students with an interest in neurobiology will also find this an instructive and practical handbook. (orig.)

Kretschmann, H.J.; Fiekert, W.; Gerke, M.; Vogt, H.; Weirich, D.; Wesemann, M. [Medizinische Hochschule Hannover (Germany). Abt. Neuroanatomie; Weinrich, W. [Staedtisches Krankenhaus Nordstadt, Hannover (Germany). Abt. fuer Neurologie

1998-12-31

155

Characterization of masses in digital breast tomosynthesis: Comparison of machine learning in projection views and reconstructed slices  

Energy Technology Data Exchange (ETDEWEB)

Purpose: In digital breast tomosynthesis (DBT), quasi-three-dimensional (3D) structural information is reconstructed from a small number of 2D projection view (PV) mammograms acquired over a limited angular range. The authors developed preliminary computer-aided diagnosis (CADx) methods for classification of malignant and benign masses and compared the effectiveness of analyzing lesion characteristics in the reconstructed DBT slices and in the PVs. Methods: A data set of MLO view DBT of 99 patients containing 107 masses (56 malignant and 51 benign) was collected at the Massachusetts General Hospital with IRB approval. The DBTs were obtained with a GE prototype system which acquired 11 PVs over a 50 deg. arc. The authors reconstructed the DBTs at 1 mm slice interval using a simultaneous algebraic reconstruction technique. The region of interest (ROI) containing the mass was marked by a radiologist in the DBT volume and the corresponding ROIs on the PVs were derived based on the imaging geometry. The subsequent processes were fully automated. For classification of masses using the DBT-slice approach, the mass on each slice was segmented by an active contour model initialized with adaptive k-means clustering. A spiculation likelihood map was generated by analysis of the gradient directions around the mass margin and spiculation features were extracted from the map. The rubber band straightening transform (RBST) was applied to a band of pixels around the segmented mass boundary. The RBST image was enhanced by Sobel filtering in the horizontal and vertical directions, from which run-length statistics texture features were extracted. Morphological features including those from the normalized radial length were designed to describe the mass shape. A feature space composed of the spiculation features, texture features, and morphological features extracted from the central slice alone and seven feature spaces obtained by averaging the corresponding features from three to 19 slices centered at the central slice were compared. For classification of masses using the PV approach, a feature extraction process similar to that described above for the DBT approach was performed on the ROIs from the individual PVs. Six feature spaces obtained from the central PV alone and by averaging the corresponding features from three to 11 PVs were formed. In each feature space for either the DBT-slice or the PV approach, a linear discriminant analysis classifier with stepwise feature selection was trained and tested using a two-loop leave-one-case-out resampling procedure. Simplex optimization was used to guide feature selection automatically within the training set in each leave-one-case-out cycle. The performance of the classifiers was evaluated by the area (A{sub z}) under the receiver operating characteristic curve. Results: The test A{sub z} values from the DBT-slice approach ranged from 0.87{+-}0.03 to 0.93{+-}0.02, while those from the PV approach ranged from 0.78{+-}0.04 to 0.84{+-}0.04. The highest test A{sub z} of 0.93{+-}0.02 from the nine-DBT-slice feature space was significantly (p=0.006) better than the highest test A{sub z} of 0.84{+-}0.04 from the nine-PV feature space. Conclusion: The features of breast lesions extracted from the DBT slices consistently provided higher classification accuracy than those extracted from the PV images.

Chan, Heang-Ping; Wu Yita; Sahiner, Berkman; Wei, Jun; Helvie, Mark A.; Zhang Yiheng; Moore, Richard H.; Kopans, Daniel B.; Hadjiiski, Lubomir; Way, Ted [Department of Radiology, University of Michigan, Ann Arbor, Michigan 48109 (United States); Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts 02114 (United States); Department of Radiology, University of Michigan, Ann Arbor, Michigan 48109 (United States)

2010-07-15

156

The study of femoral 3D reconstruction process based on anatomical parameters using a numerical method  

International Nuclear Information System (INIS)

Computer based three-dimensional (3D) reconstruction technique is widely used in clinical practices and its accuracy is still improving due to introducing of high resolution imaging modalities. Practically, two-dimensional X-ray image might be considered as one of major tools in orthopaedics, due to its lower cost and lower dose of radiation than computer tomography (CT). The purpose of the current study is generating 3D model of femoral bone using conventional X-ray images incorporating the anatomical parameters into a referential 3D model. For the 3D reconstruction, the 2D shape and specific parameters of bone were firstly measured from X-ray images. Then, the referential CT model was modified as follows: the axial scaling, shearing transformation and radial scaling. In this study, the 3D reconstruction algorithm was tested using femoral X-ray images from the 28 years old male. The current study showed that the 3D reconstruction technique by using X-ray images can be useful and feasible in clinical practices. It could easily generate 3D femoral model not only with saving time and costs, but also less radiation exposure to the patients. (author)

157

Experimental research on 3D reconstruction through range gated laser imaging  

Science.gov (United States)

A range gated laser imaging system has been designed and developed for high precision three-dimensional imaging. The system uses a Nd:YAG electro-optical Q-switched 532nm laser as transmitter, a double microchannel plate as gated sensor, and all the components are controlled by a trigger control unit with accuracy of subnanosecond. An experimental scheme is also designed to achieve high precision imaging; a sequence of 2D "slice" images are acquired in the experiment, and these images provide the basic data for 3D reconstruction. Basing on the centroid algorithm, we have developed the 3D reconstruction algorithm, and use it to reconstruct a 3D image of target from the experimental data. We compare the 3D image with the system performance model, and the results are corresponding.

Li, Sining; Lu, Wei; Zhang, Dayong; Li, Chao; Tu, Zhipeng

2014-09-01

158

Two approaches to 3D reconstruction in NMR zeugmatography  

International Nuclear Information System (INIS)

In nuclear magnetic resonance (NMR) zeugmatography, the primary data pertain to integrals of the unknown nuclear spin density f(x,y,z) over planes instead of lines in R3. Two natural approaches to reconstructing f from such data are: (1) By numerical implementation of the inverse Radon transform in three dimensions (the direct approach), and (2) by application, in two successive stages, of existing well-known algorithms for inverting the two-dimensional Radon transform (the two-stage approach). These two approaches are discussed and compared, both from a theoretical standpoint and through computer results obtained with real NMR data. For the cases studied to date the two methods appear to produce qualitatively similar results

159

Multiresolution 3-D reconstruction from side-scan sonar images.  

Science.gov (United States)

In this paper, a new method for the estimation of seabed elevation maps from side-scan sonar images is presented. The side-scan image formation process is represented by a Lambertian diffuse model, which is then inverted by a multiresolution optimization procedure inspired by expectation-maximization to account for the characteristics of the imaged seafloor region. On convergence of the model, approximations for seabed reflectivity, side-scan beam pattern, and seabed altitude are obtained. The performance of the system is evaluated against a real structure of known dimensions. Reconstruction results for images acquired by different sonar sensors are presented. Applications to augmented reality for the simulation of targets in sonar imagery are also discussed. PMID:17269632

Coiras, Enrique; Petillot, Yvan; Lane, David M

2007-02-01

160

3D reconstruction of histological sections: Application to mammary gland tissue.  

Science.gov (United States)

In this article, we present a novel method for the automatic 3D reconstruction of thick tissue blocks from 2D histological sections. The algorithm completes a high-content (multiscale, multifeature) imaging system for simultaneous morphological and molecular analysis of thick tissue samples. This computer-based system integrates image acquisition, annotation, registration, and three-dimensional reconstruction. We present an experimental validation of this tool using both synthetic and real data. In particular, we present the 3D reconstruction of an entire mouse mammary gland and demonstrate the integration of high-resolution molecular data. PMID:20232465

Arganda-Carreras, Ignacio; Fernández-González, Rodrigo; Muñoz-Barrutia, Arrate; Ortiz-De-Solorzano, Carlos

2010-10-01

 
 
 
 
161

Fully 3D PET image reconstruction with a 4D sinogram blurring kernel  

International Nuclear Information System (INIS)

Accurately modeling PET system response is essential for high-resolution image reconstruction. Traditionally, sinogram blurring effects are modeled as a 2D blur in each sinogram plane. Such 2D blurring kernel is insufficient for fully 3D PET data, which has four dimensions. In this paper, we implement a fully 3D PET image reconstruction using a 4D sinogram blurring kernel estimated from point source scans and perform phantom experiments to evaluate the improvements in image quality over methods with existing 2D blurring kernels. The results show that the proposed reconstruction method can achieve better spatial resolution and contrast recovery than existing methods. (orig.)

162

Symmetry-adapted spherical harmonics method for high-resolution 3D single-particle reconstructions.  

Science.gov (United States)

Three-dimensional (3D) reconstruction is the last and an essential step toward high-resolution structural determination in single-particle cryo-electron microscopy (cryoEM). We have implemented a new algorithm for reconstructing 3D structures of macromolecular complexes with icosahedral symmetry from cryoEM images. Icosahedral symmetry-adapted functions (ISAFs) are used to interpolate structural factors in the reciprocal space to generate a 3D reconstruction in spherical coordinates. In our implementation, we introduced a recursive method for deriving higher order ISAFs from three lower order seed functions. We demonstrate improvements of our new method in both the noise suppression and the effective resolution in 3D reconstruction over the commonly used Fourier-Bessel synthesis method introduced by Crowther et al. three decades ago. Our 3D reconstruction method can be extended to macromolecular complexes with other symmetry types and is thus likely to impact future high-resolution cryoEM single-particle reconstruction efforts in general. PMID:17977017

Liu, Hongrong; Cheng, Lingpeng; Zeng, Songjun; Cai, Canying; Zhou, Z Hong; Yang, Qibin

2008-01-01

163

Wide-angle breast tomosynthesis: initial comparative evaluation  

Science.gov (United States)

Conventional mammography is largely limited by superimposed anatomy which is alleviated by breast tomosynthesis and CT. Limited acquisition in tomosynthesis can result in significant out of plane artifacts while large angular acquisition span in CT can limit the imaging coverage of the chest wall near the breast. We propose a new breast imaging modality, wide-angle breast tomosynthesis (WBT), aimed to provide a practical compromise between 3D sampling and chest-wall coverage. This study compares lesion detection between conventional digital breast tomosynthesis, WBT, and breast CT (44°, 99°, and 198° total angle range, respectively) under equal patient dose conditions. A Monte Carlo (MC) code based on the Penelope package modeled a virtual flat-panel breast tomosynthesis system. The modalities were simulated at four breast compression levels. Glandular dose to the breast was estimated and the radiation flux was subsequently adjusted to achieve a constant mean glandular dose level of 1.5 mGy, independent of the breast thickness and acquisition geometry. Reconstructed volumes were generated using iterative reconstruction methods. Lesion detectability was estimated using contrast-to-noise-ratio. Results showed improved detection with increased angular span and compression. Evaluations also showed improved performance of WBT over DBT at lower compression levels, therefore highlighting potential for reduced breast compression when using a larger acquisition angle.

Thompson, John; Chen, Baiyu; Richard, Samuel; Bowsher, James; Samei, Ehsan

2010-04-01

164

Iterative 3-D reconstruction of vascular images from a few views: Phantom study results  

International Nuclear Information System (INIS)

Iterative 3-d reconstruction of images from a few projections for application in Digital Subtraction Angiography of cerebral blood vessels is investigated. The method reconstructs a 3-d vascular network in a series of 2-d sections by filtered back-projection and summation of the projections followed by non-linear iterative deconvolution of the filtered-summated image. The reconstruction method is tested on a 3-d wire phantom resembling vasculature. Four to eight projections are used as input, where each projection is separated by rotation and is assumed to represent a projected stack of mutually parallel axial sections. The results show that given at least 4 projections there is sufficient detail in the reconstructed phantom to determine the location of major structures

165

Comparison of 3D-OP-OSEM and 3D-FBP reconstruction algorithms for High-Resolution Research Tomograph studies: effects of randoms estimation methods  

Energy Technology Data Exchange (ETDEWEB)

The High-Resolution Research Tomograph (HRRT) is a dedicated human brain positron emission tomography (PET) scanner. Recently, a 3D filtered backprojection (3D-FBP) reconstruction method has been implemented to reduce bias in short duration frames, currently observed in 3D ordinary Poisson OSEM (3D-OP-OSEM) reconstructions. Further improvements might be expected using a new method of variance reduction on randoms (VRR) based on coincidence histograms instead of using the delayed window technique (DW) to estimate randoms. The goal of this study was to evaluate VRR in combination with 3D-OP-OSEM and 3D-FBP reconstruction techniques. To this end, several phantom studies and a human brain study were performed. For most phantom studies, 3D-OP-OSEM showed higher accuracy of observed activity concentrations with VRR than with DW. However, both positive and negative deviations in reconstructed activity concentrations and large biases of grey to white matter contrast ratio (up to 88%) were still observed as a function of scan statistics. Moreover 3D-OP-OSEM+VRR also showed bias up to 64% in clinical data, i.e. in some pharmacokinetic parameters as compared with those obtained with 3D-FBP+VRR. In the case of 3D-FBP, VRR showed similar results as DW for both phantom and clinical data, except that VRR showed a better standard deviation of 6-10%. Therefore, VRR should be used to correct for randoms in HRRT PET studies.

Velden, Floris H P van; Kloet, Reina W; Berckel, Bart N M van; Wolfensberger, Saskia P A; Lammertsma, Adriaan A; Boellaard, Ronald [Department of Nuclear Medicine and PET Research, VU University Medical Centre, PO Box 7057, 1007 MB Amsterdam (Netherlands)], E-mail: f.vvelden@vumc.nl

2008-06-21

166

Comparison of 3D-OP-OSEM and 3D-FBP reconstruction algorithms for High-Resolution Research Tomograph studies: effects of randoms estimation methods  

Science.gov (United States)

The High-Resolution Research Tomograph (HRRT) is a dedicated human brain positron emission tomography (PET) scanner. Recently, a 3D filtered backprojection (3D-FBP) reconstruction method has been implemented to reduce bias in short duration frames, currently observed in 3D ordinary Poisson OSEM (3D-OP-OSEM) reconstructions. Further improvements might be expected using a new method of variance reduction on randoms (VRR) based on coincidence histograms instead of using the delayed window technique (DW) to estimate randoms. The goal of this study was to evaluate VRR in combination with 3D-OP-OSEM and 3D-FBP reconstruction techniques. To this end, several phantom studies and a human brain study were performed. For most phantom studies, 3D-OP-OSEM showed higher accuracy of observed activity concentrations with VRR than with DW. However, both positive and negative deviations in reconstructed activity concentrations and large biases of grey to white matter contrast ratio (up to 88%) were still observed as a function of scan statistics. Moreover 3D-OP-OSEM+VRR also showed bias up to 64% in clinical data, i.e. in some pharmacokinetic parameters as compared with those obtained with 3D-FBP+VRR. In the case of 3D-FBP, VRR showed similar results as DW for both phantom and clinical data, except that VRR showed a better standard deviation of 6-10%. Therefore, VRR should be used to correct for randoms in HRRT PET studies.

van Velden, Floris H. P.; Kloet, Reina W.; van Berckel, Bart N. M.; Wolfensberger, Saskia P. A.; Lammertsma, Adriaan A.; Boellaard, Ronald

2008-06-01

167

Comparison of 3D-OP-OSEM and 3D-FBP reconstruction algorithms for High-Resolution Research Tomograph studies: effects of randoms estimation methods  

International Nuclear Information System (INIS)

The High-Resolution Research Tomograph (HRRT) is a dedicated human brain positron emission tomography (PET) scanner. Recently, a 3D filtered backprojection (3D-FBP) reconstruction method has been implemented to reduce bias in short duration frames, currently observed in 3D ordinary Poisson OSEM (3D-OP-OSEM) reconstructions. Further improvements might be expected using a new method of variance reduction on randoms (VRR) based on coincidence histograms instead of using the delayed window technique (DW) to estimate randoms. The goal of this study was to evaluate VRR in combination with 3D-OP-OSEM and 3D-FBP reconstruction techniques. To this end, several phantom studies and a human brain study were performed. For most phantom studies, 3D-OP-OSEM showed higher accuracy of observed activity concentrations with VRR than with DW. However, both positive and negative deviations in reconstructed activity concentrations and large biases of grey to white matter contrast ratio (up to 88%) were still observed as a function of scan statistics. Moreover 3D-OP-OSEM+VRR also showed bias up to 64% in clinical data, i.e. in some pharmacokinetic parameters as compared with those obtained with 3D-FBP+VRR. In the case of 3D-FBP, VRR showed similar results as DW for both phantom and clinical data, except that VRR showed a better standard deviation of 6-10%. Therefore, VRR should be used to correct for randoms in HRRT PET studies

168

Automated reconstruction algorithm for identification of 3D architectures of cribriform ductal carcinoma in situ.  

Science.gov (United States)

Ductal carcinoma in situ (DCIS) is a pre-invasive carcinoma of the breast that exhibits several distinct morphologies but the link between morphology and patient outcome is not clear. We hypothesize that different mechanisms of growth may still result in similar 2D morphologies, which may look different in 3D. To elucidate the connection between growth and 3D morphology, we reconstruct the 3D architecture of cribriform DCIS from resected patient material. We produce a fully automated algorithm that aligns, segments, and reconstructs 3D architectures from microscopy images of 2D serial sections from human specimens. The alignment algorithm is based on normalized cross correlation, the segmentation algorithm uses histogram equilization, Otsu's thresholding, and morphology techniques to segment the duct and cribra. The reconstruction method combines these images in 3D. We show that two distinct 3D architectures are indeed found in samples whose 2D histological sections are similarly identified as cribriform DCIS. These differences in architecture support the hypothesis that luminal spaces may form due to different mechanisms, either isolated cell death or merging fronds, leading to the different architectures. We find that out of 15 samples, 6 were found to have 'bubble-like' cribra, 6 were found to have 'tube-like' criba and 3 were 'unknown.' We propose that the 3D architectures found, 'bubbles' and 'tubes', account for some of the heterogeneity of the disease and may be prognostic indicators of different patient outcomes. PMID:22970156

Norton, Kerri-Ann; Namazi, Sameera; Barnard, Nicola; Fujibayashi, Mariko; Bhanot, Gyan; Ganesan, Shridar; Iyatomi, Hitoshi; Ogawa, Koichi; Shinbrot, Troy

2012-01-01

169

Optimization of PET image quality by means of 3D data acquisition and iterative image reconstruction  

International Nuclear Information System (INIS)

The experiments were performed at the latest-generation whole-body PET system ECAT EXACT HR+. For 2D data acquisition, a collimator of thin tungsten septa was positioned in the field-of-view. Prior to image reconstruction, the measured 3D data were sorted into 2D sinograms by using the Fourier rebinning (FORE) algorithm developed by M. Defrise. The standard filtered backprojection (FBP) method and an optimized ML/EM algorithm with overrelaxation for accelerated convergence were employed for image reconstruction. The spatial resolution of both methods as well as the convergence and noise properties of the ML/EM algorithm were studied in phantom measurements. Furthermore, patient data were acquired in the 2D mode as well as in the 3D mode and reconstructed with both techniques. At the same spatial resolution, the ML/EM-reconstructed images showed fewer and less prominent artefacts than the FBP-reconstructed images. The resulting improved detail conspicuously was achieved for the data acquired in the 2D mode as well as in the 3D mode. The best image quality was obtained by iterative 2D reconstruction of 3D data sets which were previously rebinned into 2D sinograms with help of the FORE algorithm. The phantom measurements revealed that 50 iteration steps with the otpimized ML/EM algorithm were sufficient to keep the relative quantitation error below 5%. (orig./MG)

170

A multiscale/multiframe approach to 3D PET data reconstruction  

International Nuclear Information System (INIS)

A multiscale/multiframe 3D reconstruction scheme for Positron Emission Tomography is presented. Usually the dimensions of the reconstructed volume or the projection space binning do not change during the image reconstruction process. In this paper we introduce the concept of time frame to the multiscale reconstruction proposed by Raheja et al. This approach can be used for the generation of images reconstructed in near real time using a suitable scale, taking full advantage of list mode reconstruction techniques. When compared with the Maximum Likelihood - Expectation Maximization algorithm (single scale ML-EM), the Multiscale/Multiframe proposed in this work improves the convergence speed in particular in cold regions, as well as performing a fast reconstruction. The generation of different image sequences at different spatial scales and times may be useful to optimize the acquisition clinical protocols on the fly. (orig.)

171

Using of Bezier Interpolation in 3D Reconstruction of Human Femur Bone  

Science.gov (United States)

The paper is focused on image acquisition and processing of CT scans of a human femur bone in order to obtain 3D reconstructions of the human femur. The objective of the presented study was to obtain 3D realistic model of the human femur bone. The reconstructed model provides useful data to the physician but more important are the data and 3D models that can be used for virtual testing of femoral implants and endoprosthesis. Using the B-spline patch a 3D volume model of the human femur bone can be achieved. This model can be easy imported in any CAD system, resulting a virtual femur model witch can be used in FEM analysis.

Toth-Tascau, Mirela; Pater, Flavius; Stoia, Dan Ioan; Menyhardt, Karoly; Rosu, Serban; Rusu, Lucian; Vigaru, Cosmina

2011-09-01

172

Morphological evolution of a 3D CME cloud reconstructed from three viewpoints  

CERN Document Server

The propagation properties of coronal mass ejections (CMEs) are crucial to predict its geomagnetic effect. A newly developed three dimensional (3D) mask fitting reconstruction method using coronagraph images from three viewpoints has been described and applied to the CME ejected on August 7, 2010. The CME's 3D localisation, real shape and morphological evolution are presented. Due to its interaction with the ambient solar wind, the morphology of this CME changed significantly in the early phase of evolution. Two hours after its initiation, it was expanding almost self-similarly. CME's 3D localisation is quite helpful to link remote sensing observations to in situ measurements. The investigated CME was propagating to Venus with its flank just touching STEREO B. Its corresponding ICME in the interplanetary space shows a possible signature of a magnetic cloud with a preceding shock in VEX observations, while from STEREO B only a shock is observed. We have calculated three principle axes for the reconstructed 3D ...

Feng, L; Wei, Y; Gan, W Q; Zhang, T L; Wang, M Y

2012-01-01

173

3D Reconstruction of the Retinal Arterial Tree Using Subject-Specific Fundus Images  

Science.gov (United States)

Systemic diseases, such as hypertension and diabetes, are associated with changes in the retinal microvasculature. Although a number of studies have been performed on the quantitative assessment of the geometrical patterns of the retinal vasculature, previous work has been confined to 2 dimensional (2D) analyses. In this paper, we present an approach to obtain a 3D reconstruction of the retinal arteries from a pair of 2D retinal images acquired in vivo. A simple essential matrix based self-calibration approach was employed for the "fundus camera-eye" system. Vessel segmentation was performed using a semi-automatic approach and correspondence between points from different images was calculated. The results of 3D reconstruction show the centreline of retinal vessels and their 3D curvature clearly. Three-dimensional reconstruction of the retinal vessels is feasible and may be useful in future studies of the retinal vasculature in disease.

Liu, D.; Wood, N. B.; Xu, X. Y.; Witt, N.; Hughes, A. D.; Samcg, Thom

174

3D Reconstruction of Ultrasonic Images Based on Matlab/Simulink  

Directory of Open Access Journals (Sweden)

Full Text Available In this study we use Matlab/Simulink as a user friendly interface to examine three recent works on UT image processing; furthermore a new method based on morphological features is proposed. A series of simulated 2D UT images of two known cysts are processed by the 4 different methods. They will serve as the input for 3D surface reconstruction package. A novel comparison way related to 2D and 3D features of cysts is provided. The weakness, the advantages and the deficiencies of each method are explained for cyst 3D reconstruction. It is shown that our novel morphological based method has good performance for online reconstruction specially.

Asad Babakhani

2006-01-01

175

Comparisons of CME morphological characteristics derived from five 3D reconstruction methods  

CERN Document Server

We compare different methods to reconstruct the three-dimensional (3D) CME morphology. The explored methods include geometric localisation, mask fitting, forward modeling, polarisation ratio and local correlation tracking plus triangulation. The five methods are applied to the same CME event, which occurred on August 7 2010. Their corresponding results are presented and compared, especially in their propagation direction and spatial extent in 3D. We find that mask fitting and geometric localisation method produce consistent results. Reconstructions including three-view observations are more precise than reconstructions done with only two views. Compared to the forward modeling method, in which a-priori shape of the CME geometry is assumed, mask fitting has more flexibility. Polarisation ratio method makes use of the Thomson scattering geometry. We find spatially the 3D CME derived from mask fitting lies mostly in the overlap region obtained with the polarisation method from COR2 A and B. In addition, mask fit...

Feng, Li; Marilena, Mierla

2012-01-01

176

GPU-Based 3D Cone-Beam CT Image Reconstruction for Large Data Volume  

Directory of Open Access Journals (Sweden)

Full Text Available Currently, 3D cone-beam CT image reconstruction speed is still a severe limitation for clinical application. The computational power of modern graphics processing units (GPUs has been harnessed to provide impressive acceleration of 3D volume image reconstruction. For extra large data volume exceeding the physical graphic memory of GPU, a straightforward compromise is to divide data volume into blocks. Different from the conventional Octree partition method, a new partition scheme is proposed in this paper. This method divides both projection data and reconstructed image volume into subsets according to geometric symmetries in circular cone-beam projection layout, and a fast reconstruction for large data volume can be implemented by packing the subsets of projection data into the RGBA channels of GPU, performing the reconstruction chunk by chunk and combining the individual results in the end. The method is evaluated by reconstructing 3D images from computer-simulation data and real micro-CT data. Our results indicate that the GPU implementation can maintain original precision and speed up the reconstruction process by 110–120 times for circular cone-beam scan, as compared to traditional CPU implementation.

Xing Zhao

2009-01-01

177

New techniques of determining focus position in gamma knife operation using 3D image reconstruction  

Science.gov (United States)

In this paper, new techniques of determining the focus of a disease position in a gamma knife operation are presented. In these techniques, the transparent 3D color image of the human body organ is reconstructed using a new three-dimensional reconstruction method, and then the position, the area, and the volume of focus of a disease such as cancer or a tumor are calculated. They are used in the gamma knife operation. The CT pictures are input into a digital image processing system. The useful information is extracted and the original data are obtained. Then the transparent 3D color image is reconstructed using these original data. By using this transparent 3D color image, the positions of the human body organ and the focus of a disease are determined in a coordinate system. While the 3D image is reconstructed, the area and the volume of human body organ and focus of a disease can be calculated at the same time. It is expressed through actual application that the positions of human body organ and focus of a disease can be determined exactly by using the transparent 3D color image. It is very useful in gamma knife operation or other surgical operation. The techniques presented in this paper have great application value.

Xiong, Yingen; Wang, Dezong; Zhou, Quan

1994-09-01

178

Gap filling strategies for 3-D-FBP reconstructions of High-Resolution Research Tomograph scans.  

Science.gov (United States)

The High-Resolution Research Tomograph (HRRT) is a dedicated human brain positron emission tomography scanner. Currently available iterative reconstruction algorithms show bias due to nonnegativity constraints. Consequently, implementation of 3-D filtered backprojection (3-D-FBP) is of interest. To apply 3-D-FBP all missing data including those due to gaps between detector heads need to be estimated. The aim of this study was to evaluate various gap filling strategies for 3-D-FBP reconstructions of HRRT data, such as linear and bilinear interpolation or constraint Fourier space gap filling (confosp). Furthermore, missing planes were estimated using segment 0 image data only (noniterative) or by using reconstructed images based on all previous segments (iterative method). Use of bilinear interpolation showed worst correspondence between reconstructed and true activity concentration, especially for small structures. Moreover, phantom data indicated that use of linear interpolation resulted in artifacts in planes located near the edge of the field-of-view. Use of confosp did not show these artifacts. Iterative estimations of the missing planes for |segments| 0 improved image quality at the cost of more computation time. Therefore, use of confosp for filling sinogram gaps with both iterative and noniterative estimation of missing planes are recommended for quantitative 3-D-FBP of HRRT studies. PMID:18599399

van Velden, Floris H P; Kloet, Reina W; van Berckel, Bart N M; Molthoff, Carla F M; Lammertsma, Adriaan A; Boellaard, Ronald

2008-01-01

179

3D Reconstruction and Restoration Monitoring of Sculptural Artworks by a Multi-Sensor Framework  

Directory of Open Access Journals (Sweden)

Full Text Available Nowadays, optical sensors are used to digitize sculptural artworks by exploiting various contactless technologies. Cultural Heritage applications may concern 3D reconstructions of sculptural shapes distinguished by small details distributed over large surfaces. These applications require robust multi-view procedures based on aligning several high resolution 3D measurements. In this paper, the integration of a 3D structured light scanner and a stereo photogrammetric sensor is proposed with the aim of reliably reconstructing large free form artworks. The structured light scanner provides high resolution range maps captured from different views. The stereo photogrammetric sensor measures the spatial location of each view by tracking a marker frame integral to the optical scanner. This procedure allows the computation of the rotation-translation matrix to transpose the range maps from local view coordinate systems to a unique global reference system defined by the stereo photogrammetric sensor. The artwork reconstructions can be further augmented by referring metadata related to restoration processes. In this paper, a methodology has been developed to map metadata to 3D models by capturing spatial references using a passive stereo-photogrammetric sensor. The multi-sensor framework has been experienced through the 3D reconstruction of a Statue of Hope located at the English Cemetery in Florence. This sculptural artwork has been a severe test due to the non-cooperative environment and the complex shape features distributed over a large surface.

Sandro Barone

2012-12-01

180

A parallel implementation of 3-d CT image reconstruction on a hypercube multiprocessor  

International Nuclear Information System (INIS)

In this paper, the authors describe how image reconstruction in computerized tomography (CT) can be parallelized on a message-passing multiprocessor. In particular, the results obtained from parallel implementation of 3-D CT image reconstruction for parallel beam geometries on the Intel hypercube, iPSC/2, are presented. A two stage pipelining approach is employed for filtering (convolution) and backprojection. The conventional sequential convolution algorithm is modified such that the symmetry of the filter kernel is fully utilized for parallelization. In the backprojection stage, the 3-D incremental algorithm, the authors' recently developed backprojection scheme which is shown to be faster than conventional algorithm, is parallelized

 
 
 
 
181

Clinical application of 3D reconstruction of tracheobronchial tree with electron beam CT  

International Nuclear Information System (INIS)

Objective: To explore the clinical promise of CT 3D reconstruction of tracheobronchial tree (TBT) by analyzing 73 cases retrospectively. Methods: All the 73 cases were collected from October 1997 to February 2000, who were scanned by EBCT with 130 kV and 630 mA. The scanning method was continuous volume scan, the slice thickness were 3 mm or 1.5 mm. All cross-sectional images were transmitted to the INSIGHT workstation and reconstructed with SSD (shaded surface display), and the threshold setting were -500 to -300 HU. Results: 3D reconstruction of TBT with EBCT could reveal the abnormal changes of TBT by many kinds of diseases including central cancer, inflammation, bronchiectasis, saber-sheath trachea, trachea cancer, congenital disorders, post-surgical changes of lung cancer, and stenoses by adjacent benign or malignant diseases. It could be used to locate the stenoses and measure stenotic extent. Of the 35 central cancer cases with 3D reconstruction, 6 cases were pestle obstructed, 15 cases cone obstructed, 5 cases interrupted irregularly, 8 cases with eccentric stenoses, and 1 case with right stem destroyed and right upper lobe bronchus obstructed. Conclusion: 3D reconstruction of TBT has characteristic sign in the diagnosis or differential diagnosis of central airway's benign or malignant stenoses, and it is of instructional value in clinical use

182

Blurring contact maps of thousands of proteins: what we can learn by reconstructing 3D structure  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background The present knowledge of protein structures at atomic level derives from some 60,000 molecules. Yet the exponential ever growing set of hypothetical protein sequences comprises some 10 million chains and this makes the problem of protein structure prediction one of the challenging goals of bioinformatics. In this context, the protein representation with contact maps is an intermediate step of fold recognition and constitutes the input of contact map predictors. However contact map representations require fast and reliable methods to reconstruct the specific folding of the protein backbone. Methods In this paper, by adopting a GRID technology, our algorithm for 3D reconstruction FT-COMAR is benchmarked on a huge set of non redundant proteins (1716 taking random noise into consideration and this makes our computation the largest ever performed for the task at hand. Results We can observe the effects of introducing random noise on 3D reconstruction and derive some considerations useful for future implementations. The dimension of the protein set allows also statistical considerations after grouping per SCOP structural classes. Conclusions All together our data indicate that the quality of 3D reconstruction is unaffected by deleting up to an average 75% of the real contacts while only few percentage of randomly generated contacts in place of non-contacts are sufficient to hamper 3D reconstruction.

Vassura Marco

2011-01-01

183

JULIDE: a software tool for 3D reconstruction and statistical analysis of autoradiographic mouse brain sections.  

Science.gov (United States)

In this article we introduce JULIDE, a software toolkit developed to perform the 3D reconstruction, intensity normalization, volume standardization by 3D image registration and voxel-wise statistical analysis of autoradiographs of mouse brain sections. This software tool has been developed in the open-source ITK software framework and is freely available under a GPL license. The article presents the complete image processing chain from raw data acquisition to 3D statistical group analysis. Results of the group comparison in the context of a study on spatial learning are shown as an illustration of the data that can be obtained with this tool. PMID:21124830

Ribes, Delphine; Parafita, Julia; Charrier, Rémi; Magara, Fulvio; Magistretti, Pierre J; Thiran, Jean-Philippe

2010-01-01

184

3D reconstruction of patient-specific femurs using Coherent Point Drift  

Directory of Open Access Journals (Sweden)

Full Text Available This paper dealt with the problem that the overlapping digital radiographs couldn`t reflect the 3D space information of the patient-specific femur in the orthopaedic surgery diagnosis. A 2D-3D non-rigid registration method based on Coherent Point Drift was proposed to realize the 3D reconstruction of the patient-specific femur before the surgery, which used biplanar digital radiographs of the patient-specific femur and the CT volume data of a generic femur. With the advantages of low cost, fast imaging speed and little radiation to the patients and doctors, this method provided more effective 3D imaging information for the femur diagnosis and preoperative plans. The registration experiments showed that the proposed method recovered the 3D model and the pose of the patient-specific femur effectively with a fast, accurate and robust registration result, which had satisfied the needs of clinical application.

Shaobin Sun

2013-02-01

185

The effect of image distortion on 3-D reconstruction of coronary bypass grafts from angiographic views.  

Science.gov (United States)

Three-dimensional (3-D) reconstructions of coronary bypass grafts performed from X-ray angiographic images may become increasingly important for the investigation of damaging mechanical stresses imposed to these vessels by the cyclic movement of the heart. Contrary to what we had experienced with coronary arteries, appreciable reconstruction artifacts frequently occur with grafts. In order to verify the hypothesis that those are caused by distortions present in the angiographic images (acquired with image intensifiers), we have implemented a grid correction technique in our 3-D reconstruction method and studied its efficiency with phantom experiments. In this article, the nature of the encountered artifacts and the way in which the dewarping correction eliminates them are illustrated by a phantom experiment and by the reconstruction of a real coronary bypass vein graft. PMID:11055790

Dorsaz, P A; Dorsaz, L; Doriot, P A

2000-07-01

186

Intermediate view reconstruction using adaptive disparity search algorithm for real-time 3D processing  

Science.gov (United States)

In this paper, intermediate view reconstruction (IVR) using adaptive disparity search algorithm (ASDA) is for realtime 3-dimensional (3D) processing proposed. The proposed algorithm can reduce processing time of disparity estimation by selecting adaptive disparity search range. Also, the proposed algorithm can increase the quality of the 3D imaging. That is, by adaptively predicting the mutual correlation between stereo images pair using the proposed algorithm, the bandwidth of stereo input images pair can be compressed to the level of a conventional 2D image and a predicted image also can be effectively reconstructed using a reference image and disparity vectors. From some experiments, stereo sequences of 'Pot Plant' and 'IVO', it is shown that the proposed algorithm improves the PSNRs of a reconstructed image to about 4.8 dB by comparing with that of conventional algorithms, and reduces the Synthesizing time of a reconstructed image to about 7.02 sec by comparing with that of conventional algorithms.

Bae, Kyung-hoon; Park, Changhan; Kim, Eun-soo

2008-03-01

187

A model-based reconstruction method for 3-D rotational coronary angiography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents a model-based reconstruction method of the coronary tree from a few number of projections in rotational angiography imaging. The reconstruction relies on projections acquired at a same cardiac phase and an energy function minimization that aims to lead the deformation of the 3D model to fit projection data whereas preserving coherence both in time and space. Some preliminary results are provided on simulated rotational angiograms.

Xie, Lizhe; Hu, Yining; Nunes, Jean-claude; Bellanger, Jean-jacques; Bedossa, Marc; Luo, Limin; Toumoulin, Christine

2010-01-01

188

A model-based reconstruction method for 3-D rotational coronary angiography  

Science.gov (United States)

This paper presents a model-based reconstruction method of the coronary tree from a few number of projections in rotational angiography imaging. The reconstruction relies on projections acquired at a same cardiac phase and an energy function minimization that aims to lead the deformation of the 3D model to fit projection data whereas preserving coherence both in time and space. Some preliminary results are provided on simulated rotational angiograms. PMID:21096600

Xie, Lizhe; Hu, Yining; Nunes, Jean-Claude; Bellanger, Jean-Jacques; Bedossa, Marc; Luo, Limin; Toumoulin, Christine

2010-01-01

189

The role of 3D Helical CT in the reconstructive treatment of maxillofacial cancers  

International Nuclear Information System (INIS)

Purpose of this work is to investigate the role of Helical CT and the usefulness of three-dimensional (3D) imaging for pre-operative planning and follow-up of reconstructive maxillofacial surgery with alloplastic material in neoplastic disease involving this region. From 1996 to 1999 eleven patients were examined with Helical CT and 3D images for planning of maxillofacial plastic and reconstructive surgery for advanced cancer of this anatomically complex region. A 3D-modulated titanium mesh (100%) or micro nets was used to rebuild the anterior surface of maxillary bone and the orbital floor. The mesh was cut to the appropriate size and shape and curved where necessary. Within the residual sinusal cavity a siliconed filling was used surmounting an acrylic prosthesis with dental arch to rebuild the palate. A rehydrated bovine pericardium was affixed and moduled on the borders in two cases only. Three-dimensionally reconstructed CT images were obtained preoperatively and at least 6 months postoperatively in all patients. The images were generated on a computer workstation using the shaded surface display (SSD) software with threshold values ranging 425 to 630 HU, and a more closed window for the imaging of titanium mesh/bone interface in the post surgical follow-up. It was obtained an excellent complete spatial depiction of maxillo facial region both before and after surgery, with no artefacts so important as to affect the 3D reconstruction process and the image quality.onstruction process and the image quality. Together with the head-neck surgical team it could be worked for preoperative planning through CT scans by different 3D points of view. The 3D reconstructed follow-up scans showed good filling of the defect in the area where the titanium mesh had been used. Then efficacious bone modelling and good biocompatibility of the alloplastic material were seen in all patients, with no inflammatory reactions. Titanium is a well-known material, which is widely used for cranioplasty. It is a radiolucent, non-ferrous metal of low atomic number that allows very clear CT and MR images to be obtained. Further Ti features are strength, biocompatibility and easy handling. 3D Helical CT scan has proven to be the most complete and accurate imaging technique for reconstructive plastic surgery with alloplastic material in advanced maxillofacial cancer, also considering the anatomic and functional complexity of his area. The prospect is provided to identify virtual 3D presurgical ablation planes. These may allow the surgeon to improve plastic reconstruction and shorten intervention time

190

Reconstruction of 3D ultrasound images based on Cyclic Regularized Savitzky-Golay filters.  

Science.gov (United States)

This paper presents a new three-dimensional (3D) ultrasound reconstruction algorithm for generation of 3D images from a series of two-dimensional (2D) B-scans acquired in the mechanical linear scanning framework. Unlike most existing 3D ultrasound reconstruction algorithms, which have been developed and evaluated in the freehand scanning framework, the new algorithm has been designed to capitalize the regularity pattern of the mechanical linear scanning, where all the B-scan slices are precisely parallel and evenly spaced. The new reconstruction algorithm, referred to as the Cyclic Regularized Savitzky-Golay (CRSG) filter, is a new variant of the Savitzky-Golay (SG) smoothing filter. The CRSG filter has been improved upon the original SG filter in two respects: First, the cyclic indicator function has been incorporated into the least square cost function to enable the CRSG filter to approximate nonuniformly spaced data of the unobserved image intensities contained in unfilled voxels and reduce speckle noise of the observed image intensities contained in filled voxels. Second, the regularization function has been augmented to the least squares cost function as a mechanism to balance between the degree of speckle reduction and the degree of detail preservation. The CRSG filter has been evaluated and compared with the Voxel Nearest-Neighbor (VNN) interpolation post-processed by the Adaptive Speckle Reduction (ASR) filter, the VNN interpolation post-processed by the Adaptive Weighted Median (AWM) filter, the Distance-Weighted (DW) interpolation, and the Adaptive Distance-Weighted (ADW) interpolation, on reconstructing a synthetic 3D spherical image and a clinical 3D carotid artery bifurcation in the mechanical linear scanning framework. This preliminary evaluation indicates that the CRSG filter is more effective in both speckle reduction and geometric reconstruction of 3D ultrasound images than the other methods. PMID:20696448

Toonkum, Pollakrit; Suwanwela, Nijasri C; Chinrungrueng, Chedsada

2011-02-01

191

HeinzelCluster: accelerated reconstruction for FORE and OSEM3D.  

Science.gov (United States)

Using iterative three-dimensional (3D) reconstruction techniques for reconstruction of positron emission tomography (PET) is not feasible on most single-processor machines due to the excessive computing time needed, especially so for the large sinogram sizes of our high-resolution research tomograph (HRRT). In our first approach to speed up reconstruction time we transform the 3D scan into the format of a two-dimensional (2D) scan with sinograms that can be reconstructed independently using Fourier rebinning (FORE) and a fast 2D reconstruction method. On our dedicated reconstruction cluster (seven four-processor systems, Intel PIII@700 MHz, switched fast ethernet and Myrinet, Windows NT Server), we process these 2D sinograms in parallel. We have achieved a speedup > 23 using 26 processors and also compared results for different communication methods (RPC, Syngo, Myrinet GM). The other approach is to parallelize OSEM3D (implementation of C Michel), which has produced the best results for HRRT data so far and is more suitable for an adequate treatment of the sinogram gaps that result from the detector geometry of the HRRT. We have implemented two levels of parallelization for four dedicated cluster (a shared memory fine-grain level on each node utilizing all four processors and a coarse-grain level allowing for 15 nodes) reducing the time for one core iteration from over 7 h to about 35 min. PMID:12200930

Vollmar, S; Michel, C; Treffert, J T; Newport, D F; Casey, M; Knöss, C; Wienhard, K; Liu, X; Defrise, M; Heiss, W D

2002-08-01

192

Some remarks concerning the influence of electron noise on 3D reconstruction  

International Nuclear Information System (INIS)

In a recent review Saxton has criticized our statement that a '3D reconstuction requires the same integral dose as a conventional 2D micrograph provided the level of significance and the resolution are identical' which has been deduced in a paper on election noise in 3D reconstruction. He states that this clain has been the subject of 'considerable discussion and confusion' and deduces from signal-to-noise considerations that this equivalence' is not borne out'. On the other hand, however, he agrees with our mathematical theory. The differences between Saxton and ourselves arise because he does not use our definition of significance. The comparison between the results of a 3D and a 2D analysis requires that the information delivered from both methods is of the same kind. There is not much sense in comparing directly the density of a 3D reconstruction with that of a projection because they are physically different. If, however, the information is concerned with structure features recognizable from a 3D reconstruction as well as from a projection, the comparison can be made. (orig.)

193

High speed stereoscopic shadowgraph imaging and its digital 3D reconstruction  

International Nuclear Information System (INIS)

A stereoscopic shadowgraph system has been developed based on the conventional z-type schlieren configuration. The test volume is set at the intersection of two inclined converging beams formed by two pairs of parabolic mirrors. Two synchronized high speed cameras are applied to record the shadowgraph image pairs simultaneously. A precisely etched metal mesh plate is used to calibrate the stereoscopic shadowgraph system. By combining the calibration parameters and coordinates of the matching points in stereo images, the depth information and the 3D view of the shadowgraph images are obtained. A crystal block with internal 3D images created by laser etching is used as a model for static object reconstruction and validation. The 3D coordinates obtained by the digital 3D reconstruction are in good agreement with the real dimensions. The developed stereoscopic technique is then applied to investigate the bursting dynamics of a bubble. The time resolved bubble-bursting process has been reconstructed successfully. The quantitative velocity measurement reveals that the bubble collapses at a constant velocity of around 7 m s?1, which corresponds to a high Weber number. As a result, finger-like structures are observable around the rim of the collapsing bubble. The stereoscopic shadowgraph technique has been shown to be effective for 3D visualization and quantitative measurement

194

High speed stereoscopic shadowgraph imaging and its digital 3D reconstruction  

Science.gov (United States)

A stereoscopic shadowgraph system has been developed based on the conventional z-type schlieren configuration. The test volume is set at the intersection of two inclined converging beams formed by two pairs of parabolic mirrors. Two synchronized high speed cameras are applied to record the shadowgraph image pairs simultaneously. A precisely etched metal mesh plate is used to calibrate the stereoscopic shadowgraph system. By combining the calibration parameters and coordinates of the matching points in stereo images, the depth information and the 3D view of the shadowgraph images are obtained. A crystal block with internal 3D images created by laser etching is used as a model for static object reconstruction and validation. The 3D coordinates obtained by the digital 3D reconstruction are in good agreement with the real dimensions. The developed stereoscopic technique is then applied to investigate the bursting dynamics of a bubble. The time resolved bubble-bursting process has been reconstructed successfully. The quantitative velocity measurement reveals that the bubble collapses at a constant velocity of around 7 m s-1, which corresponds to a high Weber number. As a result, finger-like structures are observable around the rim of the collapsing bubble. The stereoscopic shadowgraph technique has been shown to be effective for 3D visualization and quantitative measurement.

Wang, Q.; Zhang, Y.

2011-06-01

195

Encryption and volumetric 3D object reconstruction using multispectral computational integral imaging.  

Science.gov (United States)

This paper presents a new method for three-dimensional (3D) scene acquisition via reconstruction with multispectral information and its Fourier-based encryption using computational integral imaging, by which the field of view, resolution, and information security are increased, respectively. The color imaging sensors covered with a Bayer color filter array captures elemental images (EI) at different spectral bands (400 and 700 nm intervals in the visible spectrum). Subsequently, double random phase encryption (DRPE) in the Fourier domain is employed on Bayer formatted EI to encrypt the captured 3D scene. Proper 3D object reconstruction only can be achieved by applying inverse decryption and a geometric ray backpropagation algorithm on the encrypted EI. Further, the high-resolution multispectral 3D scene can be visualized by using various adaptive interpolation algorithms. To objectively evaluate our proposed method, we carried out computational experiments for 3D object sensing, reconstruction, and digital simulations for DRPE. Experiment results validate the feasibility and robustness of our proposed approach, even under severe degradation. PMID:25322135

Muniraj, Inbarasan; Kim, Byoungho; Lee, Byung-Guen

2014-09-20

196

Reconstructing photorealistic 3D models from image sequence using domain decomposition method  

Science.gov (United States)

In the fields of industrial design, artistic design and heritage conservation, physical objects are usually digitalized by reverse engineering through some 3D scanning methods. Structured light and photogrammetry are two main methods to acquire 3D information, and both are expensive. Even if these expensive instruments are used, photorealistic 3D models are seldom available. In this paper, a new method to reconstruction photorealistic 3D models using a single camera is proposed. A square plate glued with coded marks is used to place the objects, and a sequence of about 20 images is taken. From the coded marks, the images are calibrated, and a snake algorithm is used to segment object from the background. A rough 3d model is obtained using shape from silhouettes algorithm. The silhouettes are decomposed into a combination of convex curves, which are used to partition the rough 3d model into some convex mesh patches. For each patch, the multi-view photo consistency constraints and smooth regulations are expressed as a finite element formulation, which can be resolved locally, and the information can be exchanged along the patches boundaries. The rough model is deformed into a fine 3d model through such a domain decomposition finite element method. The textures are assigned to each element mesh, and a photorealistic 3D model is got finally. A toy pig is used to verify the algorithm, and the result is exciting.

Xiong, Hanwei; Pan, Ming; Zhang, Xiangwei

2009-11-01

197

3D Reconstruction of Locust Based on Improved Chan-vese Model for Biological Education  

Directory of Open Access Journals (Sweden)

Full Text Available The 3D reconstruction of infected locust is very important for the biological popular science education. Especially, the vector contour extraction of infected locust slice image is the key step in aspects of illuminating the interactive process between the locust organ and bio-pesticide. Some classic segmentation algorithms aren’t suitable for the locust image with complex topology and minimal gray scale difference which will make the 3D reconstruction incomplete, inaccurate and non-vectorial. This study applies a new adaptive multiphase segmentation method of microscopic image based on improved Chan-Vese model to the 3D reconstruction. Firstly, in order to improve the speed and accuracy of contour extraction, the complex background is removed by scanning the pixel value in horizontal and vertical direction. And a great deal of isolated noises are reduced by the decision window. Secondly, the C-V model parameters ?1, ?2 and curvature are optimized by neglecting the curvature and setting the dynamical proportion of ?1and ?2. The exact extraction of tissue contour in the locust coelom has established a good foundation for the 3D reconstruction and organ deformation parameters calculation of coelom based on the above vector data.

Qin Ma

2013-01-01

198

A Novel Image Compression Algorithm for High Resolution 3D Reconstruction  

Science.gov (United States)

This research presents a novel algorithm to compress high-resolution images for accurate structured light 3D reconstruction. Structured light images contain a pattern of light and shadows projected on the surface of the object, which are captured by the sensor at very high resolutions. Our algorithm is concerned with compressing such images to a high degree with minimum loss without adversely affecting 3D reconstruction. The Compression Algorithm starts with a single level discrete wavelet transform (DWT) for decomposing an image into four sub-bands. The sub-band LL is transformed by DCT yielding a DC-matrix and an AC-matrix. The Minimize-Matrix-Size Algorithm is used to compress the AC-matrix while a DWT is applied again to the DC-matrix resulting in LL2, HL2, LH2 and HH2 sub-bands. The LL2 sub-band is transformed by DCT, while the Minimize-Matrix-Size Algorithm is applied to the other sub-bands. The proposed algorithm has been tested with images of different sizes within a 3D reconstruction scenario. The algorithm is demonstrated to be more effective than JPEG2000 and JPEG concerning higher compression rates with equivalent perceived quality and the ability to more accurately reconstruct the 3D models.

Siddeq, M. M.; Rodrigues, M. A.

2014-06-01

199

A Smartphone Interface for a Wireless EEG Headset with Real-Time 3D Reconstruction  

DEFF Research Database (Denmark)

We demonstrate a fully functional handheld brain scanner consisting of a low-cost 14-channel EEG headset with a wireless connec- tion to a smartphone, enabling minimally invasive EEG monitoring in naturalistic settings. The smartphone provides a touch-based interface with real-time brain state decoding and 3D reconstruction.

Stopczynski, Arkadiusz; Larsen, Jakob Eg

2011-01-01

200

Array diagnostics, spatial resolution, and filtering of undesired radiation with the 3D reconstruction algorithm  

DEFF Research Database (Denmark)

This paper focuses on three important features of the 3D reconstruction algorithm of DIATOOL: the identification of array elements improper functioning and failure, the obtainable spatial resolution of the reconstructed fields and currents, and the filtering of undesired radiation and scattering to obtain a more accurate measured field. Results obtained by real measured data are presented. Special attention is given to the computational advantages given by the higher-order Method of Moments-based formulation of DIATOOL. Guidelines on the recommended measurement sampling and measured field truncation for achieving the best possible reconstruction results are also provided.

Pivnenko, Sergey

2013-01-01

 
 
 
 
201

3D reconstruction techniques made easy: know-how and pictures  

International Nuclear Information System (INIS)

Three-dimensional reconstructions represent a visual-based tool for illustrating the basis of three-dimensional post-processing such as interpolation, ray-casting, segmentation, percentage classification, gradient calculation, shading and illumination. The knowledge of the optimal scanning and reconstruction parameters facilitates the use of three-dimensional reconstruction techniques in clinical practise. The aim of this article is to explain the principles of multidimensional image processing in a pictorial way and the advantages and limitations of the different possibilities of 3D visualisation. (orig.)

202

3D reconstruction techniques made easy: know-how and pictures  

Energy Technology Data Exchange (ETDEWEB)

Three-dimensional reconstructions represent a visual-based tool for illustrating the basis of three-dimensional post-processing such as interpolation, ray-casting, segmentation, percentage classification, gradient calculation, shading and illumination. The knowledge of the optimal scanning and reconstruction parameters facilitates the use of three-dimensional reconstruction techniques in clinical practise. The aim of this article is to explain the principles of multidimensional image processing in a pictorial way and the advantages and limitations of the different possibilities of 3D visualisation. (orig.)

Luccichenti, Giacomo; Sabatini, Umberto [IRCCS Fondazione Santa Lucia, Department of Radiology, Rome (Italy); Cademartiri, Filippo; Krestin, Gabriel P. [University of Rotterdam, Department of Radiology, Erasmus Medical Center, Rotterdam (Netherlands); Pezzella, Francesca Romana [University of Rome La Sapienza, Department of Neurological Sciences, Rome (Italy); Runza, Giuseppe; Midiri, Massimo [University of Palermo, Department of Radiology, Palermo (Italy); Belgrano, Manuel [University of Trieste, Deparment of Radiology, Trieste (Italy); Bastianello, Stefano [University of Pavia, Department of Neuroradiology, Institute of Neurology, IRCCS Fondazione C. Mondino, Pavia (Italy)

2005-10-01

203

Non-periodic 3-D motion estimation and reconstruction of coronary stents  

International Nuclear Information System (INIS)

C-arm CT enables 3-D imaging at high spatial resolution. Image quality would be sufficient for coronary artery stents at rest. However, spatial resolution is severely degraded by cardiac motion which needs to be considered in the reconstruction step. Existing approaches are based on detecting markers in the projection images. Based on the exact marker locations in all images, motion estimation and compensation is performed in the 2-D projection image domain and thus no 3-D motion information of the stent is available. In this paper a novel method for computing the non-periodic location of the stent markers in 3-D is proposed. The motion estimation step comprises marker detection in 2-D, computation of periodic 3-D motion and computation of non-periodic 3-D motion. For motion compensation the 3- D marker positions are used to compute an affine motion model as input for a motion compensated FDK reconstruction algorithm. First clinical results suggest a high image quality and the possibility to compute physiological parameters e.g. velocity curves. (orig.)

204

Crime event 3D reconstruction based on incomplete or fragmentary evidence material - Case report.  

Science.gov (United States)

Using our own experience in 3D analysis, the authors will demonstrate the possibilities of 3D crime scene and event reconstruction in cases where originally collected material evidence is largely insufficient. The necessity to repeat forensic evaluation is often down to the emergence of new facts in the course of case proceedings. Even in cases when a crime scene and its surroundings have undergone partial or complete transformation, with regard to elements significant to the course of the case, or when the scene was not satisfactorily secured, it is still possible to reconstruct it in a 3D environment based on the originally-collected, even incomplete, material evidence. In particular cases when no image of the crime scene is available, its partial or even full reconstruction is still potentially feasible. Credibility of evidence for such reconstruction can still satisfy the evidence requirements in court. Reconstruction of the missing elements of the crime scene is still possible with the use of information obtained from current publicly available databases. In the study, we demonstrate that these can include Google Maps(®*), Google Street View(®*) and available construction and architecture archives. PMID:25132528

Maksymowicz, Krzysztof; Tunikowski, Wojciech; Ko?ciuk, Jacek

2014-09-01

205

Evaluation of a 3D point cloud tetrahedral tomographic reconstruction method  

Energy Technology Data Exchange (ETDEWEB)

Tomographic reconstruction on an irregular grid may be superior to reconstruction on a regular grid. This is achieved through an appropriate choice of the image space model, the selection of an optimal set of points and the use of any available prior information during the reconstruction process. Accordingly, a number of reconstruction-related parameters must be optimized for best performance. In this work, a 3D point cloud tetrahedral mesh reconstruction method is evaluated for quantitative tasks. A linear image model is employed to obtain the reconstruction system matrix and five point generation strategies are studied. The evaluation is performed using the recovery coefficient, as well as voxel- and template-based estimates of bias and variance measures, computed over specific regions in the reconstructed image. A similar analysis is performed for regular grid reconstructions that use voxel basis functions. The maximum likelihood expectation maximization reconstruction algorithm is used. For the tetrahedral reconstructions, of the five point generation methods that are evaluated, three use image priors. For evaluation purposes, an object consisting of overlapping spheres with varying activity is simulated. The exact parallel projection data of this object are obtained analytically using a parallel projector, and multiple Poisson noise realizations of these exact data are generated and reconstructed using the different point generation strategies. The unconstrained nature of point placement in some of the irregular mesh-based reconstruction strategies has superior activity recovery for small, low-contrast image regions. The results show that, with an appropriately generated set of mesh points, the irregular grid reconstruction methods can out-perform reconstructions on a regular grid for mathematical phantoms, in terms of the performance measures evaluated.

Pereira, N F; Sitek, A, E-mail: nfp4@bwh.harvard.ed, E-mail: asitek@bwh.harvard.ed [Department of Radiology, Brigham and Women' s Hospital-Harvard Medical School Boston, MA (United States)

2010-09-21

206

Evaluation of a 3D point cloud tetrahedral tomographic reconstruction method  

Science.gov (United States)

Tomographic reconstruction on an irregular grid may be superior to reconstruction on a regular grid. This is achieved through an appropriate choice of the image space model, the selection of an optimal set of points and the use of any available prior information during the reconstruction process. Accordingly, a number of reconstruction-related parameters must be optimized for best performance. In this work, a 3D point cloud tetrahedral mesh reconstruction method is evaluated for quantitative tasks. A linear image model is employed to obtain the reconstruction system matrix and five point generation strategies are studied. The evaluation is performed using the recovery coefficient, as well as voxel- and template-based estimates of bias and variance measures, computed over specific regions in the reconstructed image. A similar analysis is performed for regular grid reconstructions that use voxel basis functions. The maximum likelihood expectation maximization reconstruction algorithm is used. For the tetrahedral reconstructions, of the five point generation methods that are evaluated, three use image priors. For evaluation purposes, an object consisting of overlapping spheres with varying activity is simulated. The exact parallel projection data of this object are obtained analytically using a parallel projector, and multiple Poisson noise realizations of these exact data are generated and reconstructed using the different point generation strategies. The unconstrained nature of point placement in some of the irregular mesh-based reconstruction strategies has superior activity recovery for small, low-contrast image regions. The results show that, with an appropriately generated set of mesh points, the irregular grid reconstruction methods can out-perform reconstructions on a regular grid for mathematical phantoms, in terms of the performance measures evaluated.

Pereira, N. F.; Sitek, A.

2010-09-01

207

Evaluation of a 3D point cloud tetrahedral tomographic reconstruction method  

International Nuclear Information System (INIS)

Tomographic reconstruction on an irregular grid may be superior to reconstruction on a regular grid. This is achieved through an appropriate choice of the image space model, the selection of an optimal set of points and the use of any available prior information during the reconstruction process. Accordingly, a number of reconstruction-related parameters must be optimized for best performance. In this work, a 3D point cloud tetrahedral mesh reconstruction method is evaluated for quantitative tasks. A linear image model is employed to obtain the reconstruction system matrix and five point generation strategies are studied. The evaluation is performed using the recovery coefficient, as well as voxel- and template-based estimates of bias and variance measures, computed over specific regions in the reconstructed image. A similar analysis is performed for regular grid reconstructions that use voxel basis functions. The maximum likelihood expectation maximization reconstruction algorithm is used. For the tetrahedral reconstructions, of the five point generation methods that are evaluated, three use image priors. For evaluation purposes, an object consisting of overlapping spheres with varying activity is simulated. The exact parallel projection data of this object are obtained analytically using a parallel projector, and multiple Poisson noise realizations of these exact data are generated and reconstructed using the different point generation strategies. The unconstrained generation strategies. The unconstrained nature of point placement in some of the irregular mesh-based reconstruction strategies has superior activity recovery for small, low-contrast image regions. The results show that, with an appropriately generated set of mesh points, the irregular grid reconstruction methods can out-perform reconstructions on a regular grid for mathematical phantoms, in terms of the performance measures evaluated.

208

Combined constraints for efficient algebraic regularized methods in fully 3D reconstruction  

Science.gov (United States)

SPECT systems incorporate the use of one or more rotating gamma cameras which can be equipped with cone-beam collimators to improve the trade-off between spatial resolution and sensitivity. The geometry of the cone-beam collimators implies that a specific 3D reconstruction algorithm must be applied. Algebraic methods provide the possibility of including the physical characteristics, such as attenuation, Compton scatter and detector response, in the reconstruction process. However, the reconstruction problem is an ill-posed problem which should be regularized. This paper presents a 3D algebraic method that combines three regularizing constraints. These constraints deal respectively with penalizing negative voxels, local noise smoothing and missing data compensation. The results presented were obtained from imaging simulations, phantom data and from a thyroid clinical study of a normal volunteer.

Laurette, I.; Darcourt, J.; Blanc-Féraud, L.; Koulibaly, P. M.; Barlaud, M.

1998-04-01

209

Combined constraints for efficient algebraic regularized methods in fully 3D reconstruction  

International Nuclear Information System (INIS)

SPECT systems incorporate the use of one or more rotating gamma cameras which can be equipped with cone-beam collimators to improve the trade-off between spatial resolution and sensitivity. The geometry of the cone-beam collimators implies that a specific 3D reconstruction algorithm must be applied. Algebraic methods provide the possibility of including the physical characteristics, such as attenuation, Compton scatter and detector response, in the reconstruction process. However, the reconstruction problem is an ill-posed problem which should be regularized. This paper presents a 3D algebraic method that combines three regularizing constraints. These constraints deal respectively with penalizing negative voxels, local noise smoothing and missing data compensation. The results presented were obtained from imaging simulations, phantom data and from a thyroid clinical study of a normal volunteer. (author)

210

3D High Resolution l1-SPIRiT Reconstruction on Gadgetron based Cloud : no. 1882  

DEFF Research Database (Denmark)

Applying non-linear reconstruction to high resolution 3D MRI is challenging because of the lengthy computing time needed for those iterative algorithms. To achieve practical processing duration to enable clinical usage of non-linear reconstruction, we have extended previously published Gadgetron framework to support distributed computing in a cloud environment. This extension is named GT-Plus. A cloud version of 3D l1-SPIRiT was implemented on the GT-Plus framework. We demonstrate that a 3mins reconstruction could be achieved for 1mm3 isotropic resolution neuro scans with significantly improved image quality using two dimensional acceleration factors of R=3×2 and 3×3

Xue, Hui; Kelmann, Peter

211

Ab initio high-resolution single-particle 3D reconstructions: the symmetry adapted functions way.  

Science.gov (United States)

A protocol to attain high-resolution single-particle reconstructions is presented. The protocol is the concatenation of two procedures: one to obtain an ab initio low-resolution reconstruction, the other to determine a fixed point of the consecutive applications of fast projection matching and 3D reconstruction. It is a reciprocal space formulation where the Fourier coefficients of the 3D scattering density are expressed in terms of symmetry adapted functions and the 2D particle images are represented by their Fourier-Bessel transforms. The new protocol shows advantages in terms of speed and accuracy when compared to other methods currently in use. We illustrate its performance as applied to high-resolution cryo-electron micrographs of rotavirus. PMID:20599509

Estrozi, Leandro F; Navaza, Jorge

2010-12-01

212

Mutual information as a measure of reconstruction quality in 3D dynamic lung EIT  

Science.gov (United States)

We report on a pilot study with healthy subjects who had an MR scan in addition to EIT data acquired with the Manchester fEITER system. The MR images are used to inform the external shape of a 3D EIT reconstruction model of the thorax, and small changes in the boundary that occur during respiration are addressed by incorporating the sensitivity with respect to boundary shape into a robust reconstruction algorithm. A quantitative comparison of the image quality for different EIT reconstructions is achieved through calculation of their mutual information with a segmented MR image. A shape corrected reconstruction algorithm reduces boundary artefacts relative to a standard reconstruction, and has a greater mutual information of approximately 4% with the segmented MR image.

Crabb, M. G.; Davidson, J. L.; Little, R.; Wright, P.; Naish, J. H.; Parker, G. J. M.; Kikinis, R.; McCann, H.; Lionheart, W. R. B.

2013-04-01

213

AWE multi-axis radiographic facility: A review of 3D-reconstructions from limited data  

International Nuclear Information System (INIS)

This paper presents a 3D-reconstruction study carried out to address issues regarding the optimal number of radiographic views and their orientations in a new flash X-radiography facility. The results presented in this paper are taken from reconstructions with noiseless projection data simulated from a phantom. These idealized results have shown the relative improvements gained by adding additional views, as well as the impact of varying the view orientations and the effectiveness of various constraints to suppress reconstruction artefacts. It has been concluded that, given sufficient a priori knowledge to implement appropriate constraints, a limited number of views (as few as five in the new facility) can give reasonable reconstructions, and that the reconstruction is relatively insensitive to the view orientation

214

Recovery and Visualization of 3D Structure of Chromosomes from Tomographic Reconstruction Images  

Directory of Open Access Journals (Sweden)

Full Text Available The objectives of this work include automatic recovery and visualization of a 3D chromosome structure from a sequence of 2D tomographic reconstruction images taken through the nucleus of a cell. Structure is very important for biologists as it affects chromosome functions, behavior of the cell, and its state. Analysis of chromosome structure is significant in the detection of diseases, identification of chromosomal abnormalities, study of DNA structural conformation, in-depth study of chromosomal surface morphology, observation of in vivo behavior of the chromosomes over time, and in monitoring environmental gene mutations. The methodology incorporates thresholding based on a histogram analysis with a polyline splitting algorithm, contour extraction via active contours, and detection of the 3D chromosome structure by establishing corresponding regions throughout the slices. Visualization using point cloud meshing generates a 3D surface. The 3D triangular mesh of the chromosomes provides surface detail and allows a user to interactively analyze chromosomes using visualization software.

Tsap Leonid V

2006-01-01

215

Analytical calculation of volumes-of-intersection for iterative, fully 3-D PET reconstruction.  

Science.gov (United States)

Use of iterative algorithms to reconstruct three-dimensional (3-D) positron emission tomography (PET) data requires the computation of the system probability matrix. The pure geometrical contribution can easily be approximated by the length-of-intersection (LOI) between lines-of-response (LOR) and individual voxels. However, more accurate geometrical projectors are desirable. Therefore, we have developed a fast method for the analytical calculation of the 3-D shape and volume of volumes-of-intersection (VOI). This method provides an alternative robust projector with a uniformly continuous sampling of the image space. The enhanced calculation effort is facilitated by using several speedup techniques. Exploiting intrinsic symmetry relations and the sparseness of the system matrix allows to create an efficiently compressed matrix which can be precomputed and completely stored in memory. In addition, a new voxel addressing scheme has been implemented. This scheme avoids time-consuming symmetry transformations of voxel addresses by using an octant-wise symmetrically ordered field of voxels. The above methods have been applied for a fully 3-D, iterative reconstruction of 3-D sinograms recorded with a Siemens/CTI ECAT HR+ PET scanner. A comparison of the performance of the reconstruction using LOI weighting and VOI weighting is presented. PMID:17024839

Scheins, Jürgen J; Boschen, Fritz; Herzog, Hans

2006-10-01

216

A toolbox for ab initio 3-D reconstructions in single-particle electron microscopy.  

Science.gov (United States)

Structure determination of a novel macromolecular complex via single-particle electron microscopy depends upon overcoming the challenge of establishing a reliable 3-D reconstruction using only 2-D images. There are a variety of strategies that deal with this issue, but not all of them are readily accessible and straightforward to use. We have developed a "toolbox" of ab initio reconstruction techniques that provide several options for calculating 3-D volumes in an easily managed and tightly controlled work-flow that adheres to standard conventions and formats. This toolbox is designed to streamline the reconstruction process by removing the necessity for bookkeeping, while facilitating transparent data transfer between different software packages. It currently includes procedures for calculating ab initio reconstructions via random or orthogonal tilt geometry, tomograms, and common lines, all of which have been tested using the 50S ribosomal subunit. Our goal is that the accessibility of multiple independent reconstruction algorithms via this toolbox will improve the ease with which models can be generated, and provide a means of evaluating the confidence and reliability of the final reconstructed map. PMID:20018246

Voss, Neil R; Lyumkis, Dmitry; Cheng, Anchi; Lau, Pick-Wei; Mulder, Anke; Lander, Gabriel C; Brignole, Edward J; Fellmann, Denis; Irving, Christopher; Jacovetty, Erica L; Leung, Albert; Pulokas, James; Quispe, Joel D; Winkler, Hanspeter; Yoshioka, Craig; Carragher, Bridget; Potter, Clinton S

2010-03-01

217

Use of 3D MR reconstructions in the evaluation of glenoid bone loss: a clinical study  

Energy Technology Data Exchange (ETDEWEB)

To assess the ability of 3D MR shoulder reconstructions to accurately quantify glenoid bone loss in the clinical setting using findings at the time of arthroscopy as the gold standard. Retrospective review of patients with MR shoulder studies that included 3D MR reconstructions (3D MR) produced using an axial Dixon 3D-T1W-FLASH sequence at our institution was conducted with the following inclusion criteria: history of anterior shoulder dislocation, arthroscopy (OR) performed within 6 months of the MRI, and an estimate of glenoid bone loss made in the OR using the bare-spot method. Two musculoskeletal radiologists produced estimates of bone loss along the glenoid width, measured in mm and %, on 3D MR using the best-fit circle method, which were then compared to the OR measurements. There were a total of 15 patients (13 men, two women; mean age, 28, range, 19-51 years). There was no significant difference, on average, between the MRI (mean 3.4 mm/12.6 %; range, 0-30 %) and OR (mean, 12.7 %; range, 0-30 %) measurements of glenoid bone loss (p = 0.767). A 95 % confidence interval for the mean absolute error extended from 0.45-2.21 %, implying that, when averaged over all patients, the true mean absolute error of the MRI measurements relative to the OR measurements is expected to be less than 2.21 %. Inter-reader agreement between the two readers had an IC of 0.92 and CC of 0.90 in terms of percentage of bone loss. 3D MR reconstructions of the shoulder can be used to accurately measure glenoid bone loss. (orig.)

Gyftopoulos, Soterios; Beltran, Luis S.; Yemin, Avner; Recht, Michael P. [NYU Langone Medical Center, Department of Radiology, New York, NY (United States); Strauss, Eric; Meislin, Robert; Jazrawi, Laith [NYU Langone Medical Center, Center for Musculoskeletal Care, Department of Orthopaedic Surgery, New York, NY (United States)

2014-02-15

218

Accurate reconstruction of 3D cardiac geometry from coarsely-sliced MRI.  

Science.gov (United States)

We present a comprehensive validation analysis to assess the geometric impact of using coarsely-sliced short-axis images to reconstruct patient-specific cardiac geometry. The methods utilize high-resolution diffusion tensor MRI (DTMRI) datasets as reference geometries from which synthesized coarsely-sliced datasets simulating in vivo MRI were produced. 3D models are reconstructed from the coarse data using variational implicit surfaces through a commonly used modeling tool, CardioViz3D. The resulting geometries were then compared to the reference DTMRI models from which they were derived to analyze how well the synthesized geometries approximate the reference anatomy. Averaged over seven hearts, 95% spatial overlap, less than 3% volume variability, and normal-to-surface distance of 0.32 mm was observed between the synthesized myocardial geometries reconstructed from 8 mm sliced images and the reference data. The results provide strong supportive evidence to validate the hypothesis that coarsely-sliced MRI may be used to accurately reconstruct geometric ventricular models. Furthermore, the use of DTMRI for validation of in vivo MRI presents a novel benchmark procedure for studies which aim to substantiate their modeling and simulation methods using coarsely-sliced cardiac data. In addition, the paper outlines a suggested original procedure for deriving image-based ventricular models using the CardioViz3D software. PMID:24345413

Ringenberg, Jordan; Deo, Makarand; Devabhaktuni, Vijay; Berenfeld, Omer; Snyder, Brett; Boyers, Pamela; Gold, Jeffrey

2014-02-01

219

Intuitive terrain reconstruction using height observation-based ground segmentation and 3D object boundary estimation.  

Science.gov (United States)

Mobile robot operators must make rapid decisions based on information about the robot's surrounding environment. This means that terrain modeling and photorealistic visualization are required for the remote operation of mobile robots. We have produced a voxel map and textured mesh from the 2D and 3D datasets collected by a robot's array of sensors, but some upper parts of objects are beyond the sensors' measurements and these parts are missing in the terrain reconstruction result. This result is an incomplete terrain model. To solve this problem, we present a new ground segmentation method to detect non-ground data in the reconstructed voxel map. Our method uses height histograms to estimate the ground height range, and a Gibbs-Markov random field model to refine the segmentation results. To reconstruct a complete terrain model of the 3D environment, we develop a 3D boundary estimation method for non-ground objects. We apply a boundary detection technique to the 2D image, before estimating and refining the actual height values of the non-ground vertices in the reconstructed textured mesh. Our proposed methods were tested in an outdoor environment in which trees and buildings were not completely sensed. Our results show that the time required for ground segmentation is faster than that for data sensing, which is necessary for a real-time approach. In addition, those parts of objects that were not sensed are accurately recovered to retrieve their real-world appearances. PMID:23235454

Song, Wei; Cho, Kyungeun; Um, Kyhyun; Won, Chee Sun; Sim, Sungdae

2012-01-01

220

A method for brain 3D surface reconstruction from MR images  

Science.gov (United States)

Due to the encephalic tissues are highly irregular, three-dimensional (3D) modeling of brain always leads to complicated computing. In this paper, we explore an efficient method for brain surface reconstruction from magnetic resonance (MR) images of head, which is helpful to surgery planning and tumor localization. A heuristic algorithm is proposed for surface triangle mesh generation with preserved features, and the diagonal length is regarded as the heuristic information to optimize the shape of triangle. The experimental results show that our approach not only reduces the computational complexity, but also completes 3D visualization with good quality.

Zhao, De-xin

2014-09-01

 
 
 
 
221

Locating the Acupoint Baihui (GV20) Beneath the Cerebral Cortex with MRI Reconstructed 3D Neuroimages  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Baihui (GV20) is one of the most important acupoints of the Du meridian (the government vessel) and is commonly used in neurology and psychiatry and as a distal point of anorectal disorders by general practitioners. The anatomical relationship between the scalp region of the acupoint and the underlying corresponding cortex remains obscure. In this study, we first prepared the indicator for MRI scanning on a GE 1.5 T excite machine in a mode suitable for 3D reconstruction. The 3D Avizo softwar...

Yun-Yin Chen; Ming-Fan Lin; Fun-Jou Chen; Ein-Yiao Shen

2011-01-01

222

A Monitoring Approach for Surface Reconstruction from 3D Point Cloud  

Directory of Open Access Journals (Sweden)

Full Text Available This paper describes the surface reconstruction from 3D point cloud. The vertices of point cloud build a network of triangles using Delaunay Triangulation for 3D surface. DT plays an important role due to its guaranteed quality of triangular mesh generation. The process monitoring is emerging as a valuable tool and it is used to enhance operational efficiency. In this paper Delaunay algorithm monitors the various parameters of mesh generation and evaluates the performance of the algorithm by calculating parameters

Bharti Sood

2012-01-01

223

Artifact reduction method for improved visualization of 3D coronary artery reconstructions from rotational angiography acquisitions  

Science.gov (United States)

High quality and high resolution three dimensional reconstruction of the coronary arteries from clinically obtained rotational X-ray images during contrast injection has recently been attained through the use of advanced image processing techniques, including gating, optimal heart phase selection, motion compensation, and iterative reconstruction. While these strategies have produced excellent results despite severe angular under-sampling, the volumes that result from these techniques contain artifact/background signal features which impede both the qualitative as well as the quantitative analysis. This paper details a method for artifact removal from reconstructed 3D coronary angiograms that uses a priori image content information to maximize the background removal while minimizing influence on the reconstructed vessels. A variety of parameters are explored, and results indicate that this method can greatly improve visualization for use in the catheterization laboratory as well as reduce the impact of the visualization grey scale (window/level) on qualitative evaluation of the data.

Neubauer, Anne M.; Hansis, Eberhard; Carroll, John D.; Grass, Michael

2010-02-01

224

Microwave image reconstruction from 3-D fields coupled to 2-D parameter estimation.  

Science.gov (United States)

An efficient Gauss-Newton iterative imaging technique utilizing a three-dimensional (3-D) field solution coupled to a two-dimensional (2-D) parameter estimation scheme (3-D/2-D) is presented for microwave tomographic imaging in medical applications. While electromagnetic wave propagation is described fully by a 3-D vector field, a 3-D scalar model has been applied to improve the efficiency of the iterative reconstruction process with apparently limited reduction in accuracy. In addition, the image recovery has been restricted to 2-D but is generalizable to three dimensions. Image artifacts related primarily to 3-D effects are reduced when compared with results from an entirely two-dimensional inversion (2-D/2-D). Important advances in terms of improving algorithmic efficiency include use of a block solver for computing the field solutions and application of the dual mesh scheme and adjoint approach for Jacobian construction. Methods which enhance the image quality such as the log-magnitude/unwrapped phase minimization were also applied. Results obtained from synthetic measurement data show that the new 3-D/2-D algorithm consistently outperforms its 2-D/2-D counterpart in terms of reducing the effective imaging slice thickness in both permittivity and conductivity images over a range of inclusion sizes and background medium contrasts. PMID:15084072

Fang, Qianqian; Meaney, Paul M; Geimer, Shireen D; Streltsov, Anatoly V; Paulsen, Keith D

2004-04-01

225

3D reconstruction of hollow parts analyzing images acquired by a fiberscope  

Science.gov (United States)

A modified fiberscope used to reconstruct difficult-to-reach inner structures is presented. By substituting the fiberscope’s original illumination system, we can project a profile-revealing light line inside the object of study. The light line is obtained using a sandwiched power light-emitting diode (LED) attached to an extension arm on the tip of the fiberscope. Profile images from the interior of the object are then captured by a camera attached to the fiberscope’s eyepiece. Using a series of those images at different positions, the system is capable of generating a 3D reconstruction of the object with submillimeter accuracy. Also proposed is the use of a combination of known filters to remove the honeycomb structures produced by the fiberscope and the use of ring gages to obtain the extrinsic parameters of the camera attached to the fiberscope and the metrological traceability of the system. Several standard ring diameter measurements were compared against their certified values to improve the accuracy of the system. To exemplify an application, a 3D reconstruction of the interior of a refrigerator duct was conducted. This reconstruction includes accuracy assessment by comparing the measurements of the system to a coordinate measuring machine. The system, as described, is capable of 3D reconstruction of the interior of objects with uniform and non-uniform profiles from 10 to 60 mm in transversal dimensions and a depth of 1000 mm if the material of the walls of the object is translucent and allows the detection of the power LED light from the exterior through the wall. If this is not possible, we propose the use of a magnetic scale which reduces the working depth to 170 mm. The assessed accuracy is around ±0.15 mm in 2D cross-section reconstructions and ±1.3 mm in 1D position using a magnetic scale, and ±0.5 mm using a CCD camera.

Icasio-Hernández, Octavio; Gonzalez-Barbosa, José-Joel; Hurtado-Ramos, Juan B.; Viliesid-Alonso, Miguel

2014-07-01

226

CAVAREV-an open platform for evaluating 3D and 4D cardiac vasculature reconstruction  

Energy Technology Data Exchange (ETDEWEB)

The 3D reconstruction of cardiac vasculature, e.g. the coronary arteries, using C-arm CT (rotational angiography) is an active and challenging field of research. There are numerous publications on different reconstruction techniques. However, there is still a lack of comparability of achieved results for several reasons: foremost, datasets used in publications are not open to public and thus experiments are not reproducible by other researchers. Further, the results highly depend on the vasculature motion, i.e. cardiac and breathing motion patterns which are also not comparable across publications. We aim to close this gap by providing an open platform, called Cavarev (CArdiac VAsculature Reconstruction EValuation). It features two simulated dynamic projection datasets based on the 4D XCAT phantom with contrasted coronary arteries which was derived from patient data. In the first dataset, the vasculature undergoes a continuous periodic motion. The second dataset contains aperiodic heart motion by including additional breathing motion. The geometry calibration and acquisition protocol were obtained from a real-world C-arm system. For qualitative evaluation of the reconstruction results, the correlation of the morphology is used. Two segmentation-based quality measures are introduced which allow us to assess the 3D and 4D reconstruction quality. They are based on the spatial overlap of the vasculature reconstruction with the ground truth. The measures enable a comprehensive analysis and comparison of reconstruction results independent from the utilized reconstruction algorithm. An online platform (www.cavarev.com) is provided where the datasets can be downloaded, researchers can manage and publish algorithm results and download a reference C++ and Matlab implementation.

Rohkohl, Christopher; Hornegger, Joachim [Pattern Recognition Lab, Department of Computer Science, Friedrich-Alexander University Erlangen-Nuremberg, Martensstr. 3, 91058 Erlangen (Germany); Lauritsch, Guenter [Siemens AG, Healthcare Sector, Siemensstr. 1, 91301 Forchheim (Germany); Keil, Andreas, E-mail: christopher.rohkohl@informatik.uni-erlangen.d, E-mail: guenter.lauritsch@siemens.co, E-mail: andreas.keil@cs.tum.ed, E-mail: joachim.hornegger@informatik.uni-erlangen.d [Computer Aided Medical Procedures and Augmented Reality, TU Muenchen, Boltzmannstr. 3, 85748 Garching (Germany)

2010-05-21

227

Applicator reconstruction in MRI 3D image-based dose planning of brachytherapy for cervical cancer  

International Nuclear Information System (INIS)

Background and purpose: To elaborate a method for applicator reconstruction for MRI-based brachytherapy for cervical cancer. Materials and methods: Custom-made plastic catheters with a copper sulphate solution were made for insertion in the source channels of MR-CT compatible applicators: plastic and titanium tandem ring applicators, and titanium needles. The applicators were CT and MR scanned in a phantom for accurate 3D assessment of applicator visibility and geometry. A reconstruction method was developed and evaluated in 19 patient MR examinations with ring applicator (plastic: 14, titanium: 5). MR applicator reconstruction uncertainties related to inter-observer variation were evaluated. Results: The catheters were visible in the plastic applicator on T1-weighted images in phantom and in 14/14 clinical applications. On T2-weighted images, the catheters appeared weaker but still visible in phantom and in 13/14 MR clinical applications. In the titanium applicator, the catheters could not be separated from the artifacts from the applicator itself. However, these artifacts could be used to localize both titanium ring applicator (5/5 clinical applications) and needles (6/6 clinical applications). Standard deviations of inter-observer differences were below 2 mm in all directions. Conclusion: 3D applicator reconstruction based on MR imaging could be performed for plastic and titanium applicators. Plastic applicators proved well to be suited for MRI-based reconstruction to be suited for MRI-based reconstruction. For improved practicability of titanium applicator reconstruction, development of MR applicator markers is essential. Reconstruction of titanium applicator and needles at 1.5 T MR requires geometric evaluations in phantoms before using the applicator in patients.

228

Application of 3D Photo-reconstruction techniques in Geomorphology: Examples through different landforms and scales  

Science.gov (United States)

Recent developments made in tri-dimensional photo-reconstruction techniques (3D-PR), such as the use of Structure from Motion (SfM) and MultiView Stereo (MVS) techniques together, have allowed obtaining high resolution 3D point clouds. In order to achieve final point clouds with these techniques, only oblique images from consumer un-calibrated and non-metric cameras are needed. Here, these techniques are used in order to measure, monitor and quantify geomorphological features and processes. Three different applications through a range of scales and landforms are presented here. Firstly, five small gully headcuts located in a small catchment in SW Spain were monitored with the aim of estimating headcut retreat rates. During this field work, 3D models obtained by means of a Terrestrial Laser Scanner (TLS) were captured and used as benchmarks to analyze 3D-PR method accuracy. Results of this analysis showed centimeter-level accuracies with average distances between the 3D-PR model and the TLS model ranging from 0.009 to 0.025 m. Estimated soil loss ranged from -0.246 m3 to 0.114 m3 for a wet period (289 mm) of 54 days in 2013. Secondly, a calanchi type badland in Sicily (Italy) was photo-reconstructed and the quality of the 3D-PR model was analyzed using a Digital Elevation Model produced by classic digital photogrammetry with photos captured by an Unmanned Aerial Vehicle (UAV). In this case, sub-meter calculated accuracies (0.30) showed that it is possible to describe badland morphology using 3D-PR models but it is not feasible to use these models to quantify annual rates of soil erosion in badlands (10 mm eroded per year). Finally, a high-resolution model of the Veleta rock glacier (in SE Spain) was elaborated with 3D-PR techniques and compared with a 3D model obtained by means of a TLS. Results indicated that 3D-PR method can be applied to the micro-scale study of glacier morphologies and processes with average distances to the TLS point cloud of 0.21 m.

Gómez-Gutiérrez, Álvaro; Susanne, Schnabel; Conoscenti, Christian; Caraballo-Arias, Nathalie A.; Ferro, Vito; di Stefano, Constanza; Juan de Sanjosé, José; Berenguer-Sempere, Fernando; de Matías, Javier

2014-05-01

229

3D alternating direction TV-based cone-beam CT reconstruction with efficient GPU implementation.  

Science.gov (United States)

Iterative image reconstruction (IIR) with sparsity-exploiting methods, such as total variation (TV) minimization, claims potentially large reductions in sampling requirements. However, the computation complexity becomes a heavy burden, especially in 3D reconstruction situations. In order to improve the performance for iterative reconstruction, an efficient IIR algorithm for cone-beam computed tomography (CBCT) with GPU implementation has been proposed in this paper. In the first place, an algorithm based on alternating direction total variation using local linearization and proximity technique is proposed for CBCT reconstruction. The applied proximal technique avoids the horrible pseudoinverse computation of big matrix which makes the proposed algorithm applicable and efficient for CBCT imaging. The iteration for this algorithm is simple but convergent. The simulation and real CT data reconstruction results indicate that the proposed algorithm is both fast and accurate. The GPU implementation shows an excellent acceleration ratio of more than 100 compared with CPU computation without losing numerical accuracy. The runtime for the new 3D algorithm is about 6.8 seconds per loop with the image size of 256 × 256 × 256 and 36 projections of the size of 512 × 512. PMID:25045400

Cai, Ailong; Wang, Linyuan; Zhang, Hanming; Yan, Bin; Li, Lei; Xi, Xiaoqi; Guan, Min; Li, Jianxin

2014-01-01

230

Comparison of 3D Reconstructive Technologies Used for Morphometric Research and the Translation of Knowledge Using a Decision Matrix  

Science.gov (United States)

The use of three-dimensional (3D) models for education, pre-operative assessment, presurgical planning, and measurement have become more prevalent. With the increase in prevalence of 3D models there has also been an increase in 3D reconstructive software programs that are used to create these models. These software programs differ in…

Martin, Charys M.; Roach, Victoria A.; Nguyen, Ngan; Rice, Charles L.; Wilson, Timothy D.

2013-01-01

231

In-line monitoring and reverse 3D model reconstruction in additive manufacturing  

DEFF Research Database (Denmark)

Additive manufacturing allows for close-to unrestrained geometrical freedom in part design. The ability to manufacture geometries of such complexity is however limited by the fact that it proves difficult to verify tolerances of these parts. Tolerancs of featuress that are inaccessible with traditional measuring equipment such as Coordinate Measurement Machines (CMM's) can not easily be verified. This paradox is addresses by the proposal of an in-line reverse engineering and 3D reconstruction method that alows for a true to scale reconstruction of a part that is being additivelymanufactures on 3D printing (3DP), or Selective Laser Sintering (SLS) equipment. The system will be implemented and tested on a 3DP machine with modifications developed at the author's university.

Pedersen, David Bue Technical University of Denmark,

2010-01-01

232

Utility of reconstructed image from 3-D MRI in the region of oral cavity  

International Nuclear Information System (INIS)

The 3-D MRI with short TR was performed in the region of oral cavity, jaw and face, and utility of the reconstructed image was examined. Subjects were 8 healthy volunteers and 12 patients. The 3-D MRI was performed using SPGR with the following parameters; TR: 8 or 9 msec, TE: 2 or 3 msec, and FA: 20-30 degrees. Imaging direction was vertical to body axis. The matrix number was 256 x 192, slice thickness was 1 mm, slice interval was 0 and slice number was 128. The obtained image was reconstructed using software Reformat''. Detectability of temporomandibular joint disc was not enough in 8 of 20 cases. Detectability of mandibular canal was clear in 18 of 20 cases. In panorama MRI, soft tissue such as submandibular gland was detected. But, in hard tissue such as teeth or maxilla, there was a more little information in panorama MRI than in panorama X-ray photography. (K.H.)

233

Structured-Light Sensor Using Two Laser Stripes for 3D Reconstruction without Vibrations  

Directory of Open Access Journals (Sweden)

Full Text Available 3D reconstruction based on laser light projection is a well-known method that generally provides accurate results. However, when this method is used for inspection in uncontrolled environments, it is greatly affected by vibrations. This paper presents a structured-light sensor based on two laser stripes that provides a 3D reconstruction without vibrations. Using more than one laser stripe provides redundant information than is used to compensate for the vibrations. This work also proposes an accurate calibration process for the sensor based on standard calibration plates. A series of experiments are performed to evaluate the proposed method using a mechanical device that simulates vibrations. Results show excellent performance, with very good accuracy.

Rubén Usamentiaga

2014-10-01

234

Structured-Light Sensor Using Two Laser Stripes for 3D Reconstruction without Vibrations.  

Science.gov (United States)

3D reconstruction based on laser light projection is a well-known method that generally provides accurate results. However, when this method is used for inspection in uncontrolled environments, it is greatly affected by vibrations. This paper presents a structured-light sensor based on two laser stripes that provides a 3D reconstruction without vibrations. Using more than one laser stripe provides redundant information than is used to compensate for the vibrations. This work also proposes an accurate calibration process for the sensor based on standard calibration plates. A series of experiments are performed to evaluate the proposed method using a mechanical device that simulates vibrations. Results show excellent performance, with very good accuracy. PMID:25347586

Usamentiaga, Rubén; Molleda, Julio; Garcia, Daniel F

2014-01-01

235

The Isprs Benchmark on Urban Object Classification and 3d Building Reconstruction  

Science.gov (United States)

For more than two decades, many efforts have been made to develop methods for extracting urban objects from data acquired by airborne sensors. In order to make the results of such algorithms more comparable, benchmarking data sets are of paramount importance. Such a data set, consisting of airborne image and laserscanner data, has been made available to the scientific community. Researchers were encouraged to submit results of urban object detection and 3D building reconstruction, which were evaluated based on reference data. This paper presents the outcomes of the evaluation for building detection, tree detection, and 3D building reconstruction. The results achieved by different methods are compared and analysed to identify promising strategies for automatic urban object extraction from current airborne sensor data, but also common problems of state-of-the-art methods.

Rottensteiner, F.; Sohn, G.; Jung, J.; Gerke, M.; Baillard, C.; Benitez, S.; Breitkopf, U.

2012-07-01

236

3D RECONSTRUCTION AND ANALYSIS OF THE FRAGMENTED GRAINS IN A COMPOSITE MATERIAL  

Directory of Open Access Journals (Sweden)

Full Text Available X-ray microtomography from solid propellant allows studying the microstructure of fragmented grains in damaged samples. A new reconstruction algorithm of fragmented grains for 3D images is introduced. Based on a watershed transform of a morphological closing of the input image, the algorithm can be used  with different sets of markers. Two of them are compared. After the grain reconstruction, a multiscale segmentation  algorithm is used to extract each fragment of the damaged grains. This allows an original quantitative study of the  fragmentation of each grain in 3D. Experimental results on X-ray microtomographic images of a solid propellant fragmented under compression are presented and validated.

Luc Gillibert

2013-06-01

237

Robust Stereo-Vision Based 3D Object Reconstruction for the Assistive Robot FRIEND  

Directory of Open Access Journals (Sweden)

Full Text Available A key requirement of assistive robot vision is the robust 3D object reconstruction in complex environments for reliable autonomous object manipulation. In this paper the idea is presented of achieving high robustness of a complete robot vision system against external influences such as variable illumination by including feedback control of the object segmentation in stereo images. The approach used is to change the segmentation parameters in closed-loop so that object features extraction is driven to a desired result. Reliable feature extraction is necessary to fully exploit a neuro-fuzzy classifier which is the core of the proposed 2D object recognition method, predecessor of 3D object reconstruction. Experimental results on the rehabilitation assistive robotic system FRIEND demonstrate the effectiveness of the proposed method.

COJBASIC, Z.

2011-11-01

238

Estimation of solar prominence magnetic fields based on the reconstructed 3D trajectories of prominence knots  

CERN Document Server

We present an estimation of the lower limits of local magnetic fields in quiescent, activated, and active (surges) promineces, based on reconstructed 3-dimensional (3D) trajectories of individual prominence knots. The 3D trajectories, velocities, tangential and centripetal accelerations of the knots were reconstructed using observational data collected with a single ground-based telescope equipped with a Multi-channel Subtractive Double Pass imaging spectrograph. Lower limits of magnetic fields channeling observed plasma flows were estimated under assumption of the equipartition principle. Assuming approximate electron densities of the plasma n_e = 5*10^{11} cm^{-3} in surges and n_e = 5*10^{10} cm^{-3} in quiescent/activated prominences, we found that the magnetic fields channeling two observed surges range from 16 to 40 Gauss, while in quiescent and activated prominences they were less than 10 Gauss. Our results are consistent with previous detections of weak local magnetic fields in the solar prominences.

Zapiór, Maciej

2012-01-01

239

Estimation of Solar Prominence Magnetic Fields Based on the Reconstructed 3D Trajectories of Prominence Knots  

Science.gov (United States)

We present an estimation of the lower limits of local magnetic field strengths in quiescent, activated, and active (surges) prominences, based on reconstructed three-dimensional (3D) trajectories of individual prominence knots. The 3D trajectories, velocities, tangential and centripetal accelerations of the knots were reconstructed using observational data collected with a single ground-based telescope equipped with a Multi-channel Subtractive Double Pass imaging spectrograph. Lower limits of magnetic fields channeling observed plasma flows were estimated under assumption of the equipartition principle. Assuming approximate electron densities of the plasma n e=5×1011 cm-3 in surges and n e=5×1010 cm-3 in quiescent/activated prominences, we found that the magnetic fields channeling two observed surges range from 16 to 40 Gauss, while in quiescent and activated prominences they were less than 10 Gauss. Our results are consistent with previous detections of weak local magnetic fields in the solar prominences.

Zapiór, Maciej; Rudawy, Pawe?

2012-10-01

240

Practical implications of GPR investigation using 3D data reconstruction and transmission tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Non-destructive investigation using ground penetrating radar is becoming more popular in the inspection of civil structures. Currently, traditional 2D imaging is used as a preliminary tool to fi nd possible areas of interest for more detailed inspection, which can be accomplished by more advanced techniques like 3D image reconstruction or tomography. In this paper, a general overview of the work done at University of Minho regarding these techniques is presented, together wi...

Topczewski, Lukasz; Fernandes, Francisco M.; Cruz, Paulo J. S.; Lourenc?o, Paulo B.

2007-01-01

 
 
 
 
241

In-line monitoring and reverse 3D model reconstruction in additive manufacturing  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Additive manufacturing allows for close-to unrestrained geometrical freedom in part design. The ability to manufacture geometries of such complexity is however limited by the fact that it proves difficult to verify tolerances of these parts. Tolerancs of featuress that are inaccessible with traditional measuring equipment such as Coordinate Measurement Machines (CMM's) can not easily be verified. This paradox is addresses by the proposal of an in-line reverse engineering and 3D reconstruction...

Pedersen, David Bue; Hansen, Hans Nørgaard; Nielsen, Jakob Skov

2010-01-01

242

3D Reflectivity Reconstruction by Means of Spatially Distributed Kalman Filters  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In seismic, radar, and sonar imaging the exact determination of the reflectivity distribution is usually intractable so that approximations have to be applied. A method called synthetic aperture focusing technique (SAFT) is typically used for such applications as it provides a fast and simple method to reconstruct (3D) images. Nevertheless, this approach has several drawbacks such as causing image artifacts as well as offering no possibility to model system-specific uncertainties. In this pap...

Schwarzenberg, Gregor F.; Mayer, Uwe; Ruiter, Nicole V.; Hanebeck, Uwe D.

2008-01-01

243

Robust Stereo-Vision Based 3D Object Reconstruction for the Assistive Robot FRIEND  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A key requirement of assistive robot vision is the robust 3D object reconstruction in complex environments for reliable autonomous object manipulation. In this paper the idea is presented of achieving high robustness of a complete robot vision system against external influences such as variable illumination by including feedback control of the object segmentation in stereo images. The approach used is to change the segmentation parameters in closed-loop so that object features extraction ...

Cojbasic, Z.; Graser, A.; Grigorescu, S. M.; Ristic-durrant, D.; Nikolic, V.

2011-01-01

244

Sensor Fusion of Cameras and a Laser for City-Scale 3D Reconstruction  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a sensor fusion system of cameras and a 2D laser sensorfor large-scale 3D reconstruction. The proposed system is designed to capture data on afast-moving ground vehicle. The system consists of six cameras and one 2D laser sensor,and they are synchronized by a hardware trigger. Reconstruction of 3D structures is doneby estimating frame-by-frame motion and accumulating vertical laser scans, as in previousworks. However, our approach does not assume near 2D motion, but estimates free motion(including absolute scale in 3D space using both laser data and image features. In orderto avoid the degeneration associated with typical three-point algorithms, we present a newalgorithm that selects 3D points from two frames captured by multiple cameras. The problemof error accumulation is solved by loop closing, not by GPS. The experimental resultsshow that the estimated path is successfully overlaid on the satellite images, such that thereconstruction result is very accurate.

Yunsu Bok

2014-11-01

245

Regularization design in penalized maximum-likelihood image reconstruction for lesion detection in 3D PET  

Science.gov (United States)

Detecting cancerous lesions is a major clinical application in emission tomography. In previous work, we have studied penalized maximum-likelihood (PML) image reconstruction for the detection task and proposed a method to design a shift-invariant quadratic penalty function to maximize detectability of a lesion at a known location in a two dimensional image. Here we extend the regularization design to maximize detectability of lesions at unknown locations in fully 3D PET. We used a multiview channelized Hotelling observer (mvCHO) to assess the lesion detectability in 3D images to mimic the condition where a human observer examines three orthogonal views of a 3D image for lesion detection. We derived simplified theoretical expressions that allow fast prediction of the detectability of a 3D lesion. The theoretical results were used to design the regularization in PML reconstruction to improve lesion detectability. We conducted computer-based Monte Carlo simulations to compare the optimized penalty with the conventional penalty for detecting lesions of various sizes. Only true coincidence events were simulated. Lesion detectability was also assessed by two human observers, whose performances agree well with that of the mvCHO. Both the numerical observer and human observer results showed a statistically significant improvement in lesion detection by using the proposed penalty function compared to using the conventional penalty function.

Yang, Li; Zhou, Jian; Ferrero, Andrea; Badawi, Ramsey D.; Qi, Jinyi

2014-01-01

246

3D Coronal Density Reconstruction and Retrieving the Magnetic Field Structure during Solar Minimum  

Science.gov (United States)

Measurement of the coronal magnetic field is a crucial ingredient in understanding the nature of solar coronal phenomena at all scales. We employed STEREO/COR1 data obtained during a deep minimum of solar activity in February 2008 (Carrington Rotation CR 2066) to retrieve and analyze the three-dimensional (3D) coronal electron density in the range of heights from 1.5 to 4 R? using a tomography method. With this, we qualitatively deduced structures of the coronal magnetic field. The 3D electron-density analysis is complemented by the 3D STEREO/EUVI emissivity in the 195 Å band obtained by tomography for the same CR. A global 3D MHD model of the solar corona was used to relate the reconstructed 3D density and emissivity to open/closed magnetic-field structures. We show that the density-maximum locations can serve as an indicator of current-sheet position, while the locations of the density-gradient maximum can be a reliable indicator of coronal-hole boundaries. We find that the magnetic-field configuration during CR 2066 has a tendency to become radially open at heliocentric distances greater than 2.5 R?. We also find that the potential-field model with a fixed source surface is inconsistent with the boundaries between the regions with open and closed magnetic-field structures. This indicates that the assumption of the potential nature of the coronal global magnetic field is not satisfied even during the deep solar minimum. Results of our 3D density reconstruction will help to constrain solar coronal-field models and test the accuracy of the magnetic-field approximations for coronal modeling.

Kramar, M.; Airapetian, V.; Miki?, Z.; Davila, J.

2014-08-01

247

Reconstruction of 3d video from 2d real-life sequences  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: English Abstract in spanish En este artículo, se propone un método novedoso que permite generar secuencias de video en 3D usando secuencias de video reales en 2D. La reconstrucción de la secuencia de video en 3D se realiza usando el cálculo del mapa de profundidad y la síntesis de anaglifos. El mapa de profundidad es formado u [...] sando la técnica de correspondencia estéreo basada en la minimización de la energía de error global a partir de funciones de suavizado. La construcción del anaglifo es realizada usando la alineación del componente de color interpolándolo con el mapa de profundidad previamente formado. Adicionalmente, se emplea la transformación del mapa de profundidad para reducir el rango dinámico de los valores de disparidad, minimizando el efecto fantasma mejorando la preservación de color. Se usaron numerosas secuencias de video a color reales que contienen diferentes tipos de movimientos como traslacional, rotacional, acercamiento, y la combinación de los anteriores, demostrando buen funcionamiento visual de la reconstrucción de secuencias de video en 3D propuesta. Abstract in english In this paper, a novel method that permits to generate 3D video sequences using 2D real-life sequences is proposed. Reconstruction of 3D video sequence is realized using depth map computation and anaglyph synthesis. The depth map is formed employing the stereo matching technique based on global erro [...] r energy minimization with smoothing functions. The anaglyph construction is implemented using the red component alignment interpolating the previously formed depth map. Additionally, the depth map transformation is realized in order to reduce the dynamic range of the disparity values, minimizing ghosting and enhancing color preservation. Several real-life color video sequences that contain different types of motions, such as translational, rotational, zoom and combination of previous ones are used demonstrating good visual performance of the proposed 3D video sequence reconstruction.

Eduardo, Ramos Diaz; Volodymyr, Ponomaryov.

2010-12-01

248

3D reconstruction of a carotid bifurcation from 2D transversal ultrasound images.  

Science.gov (United States)

Visualizing and analyzing the morphological structure of carotid bifurcations are important for understanding the etiology of carotid atherosclerosis, which is a major cause of stroke and transient ischemic attack. For delineation of vasculatures in the carotid artery, ultrasound examinations have been widely employed because of a noninvasive procedure without ionizing radiation. However, conventional 2D ultrasound imaging has technical limitations in observing the complicated 3D shapes and asymmetric vasodilation of bifurcations. This study aims to propose image-processing techniques for better 3D reconstruction of a carotid bifurcation in a rat by using 2D cross-sectional ultrasound images. A high-resolution ultrasound imaging system with a probe centered at 40MHz was employed to obtain 2D transversal images. The lumen boundaries in each transverse ultrasound image were detected by using three different techniques; an ellipse-fitting, a correlation mapping to visualize the decorrelation of blood flow, and the ellipse-fitting on the correlation map. When the results are compared, the third technique provides relatively good boundary extraction. The incomplete boundaries of arterial lumen caused by acoustic artifacts are somewhat resolved by adopting the correlation mapping and the distortion in the boundary detection near the bifurcation apex was largely reduced by using the ellipse-fitting technique. The 3D lumen geometry of a carotid artery was obtained by volumetric rendering of several 2D slices. For the 3D vasodilatation of the carotid bifurcation, lumen geometries at the contraction and expansion states were simultaneously depicted at various view angles. The present 3D reconstruction methods would be useful for efficient extraction and construction of the 3D lumen geometries of carotid bifurcations from 2D ultrasound images. PMID:24965564

Yeom, Eunseop; Nam, Kweon-Ho; Jin, Changzhu; Paeng, Dong-Guk; Lee, Sang-Joon

2014-12-01

249

On the Performance Evaluation of 3D Reconstruction Techniques from a Sequence of Images  

Directory of Open Access Journals (Sweden)

Full Text Available The performance evaluation of 3D reconstruction techniques is not a simple problem to solve. This is not only due to the increased dimensionality of the problem but also due to the lack of standardized and widely accepted testing methodologies. This paper presents a unified framework for the performance evaluation of different 3D reconstruction techniques. This framework includes a general problem formalization, different measuring criteria, and a classification method as a first step in standardizing the evaluation process. Performance characterization of two standard 3D reconstruction techniques, stereo and space carving, is also presented. The evaluation is performed on the same data set using an image reprojection testing methodology to reduce the dimensionality of the evaluation domain. Also, different measuring strategies are presented and applied to the stereo and space carving techniques. These measuring strategies have shown consistent results in quantifying the performance of these techniques. Additional experiments are performed on the space carving technique to study the effect of the number of input images and the camera pose on its performance.

Aly Farag

2005-08-01

250

Noninterferometric tomographic reconstruction of 3D static and dynamic phase and amplitude objects  

Science.gov (United States)

Non-interferometric intensity based methods of phase retrieval such as the transport of intensity (TI) employs a simple experimental technique for amplitude and phase reconstruction of a static object by capturing several diffraction patterns at different observation planes. The purpose of this work is to numerically and experimentally extend this technique to moving phase and amplitude objects. The simulation part is done based on solving the TI equation (TIE) using the Fast Fourier Transform (FFT) method, and the amplitude and the calculated phase in the detection plane is numerically back-propagated to the object plane using the paraxial transfer function. Furthermore, we illustrate how a static 3D phase and/or amplitude object can also be reconstructed tomographically by illuminating it at multiple angles. For illustration purposes, the object is mounted on a rotating stage and multiple diffraction patterns are captured for different angles and at different observation planes. The reconstructed optical fields are tomographically recomposed to yield the final 3D shape using a simple multiplicative technique. The tomographic technique can be generalized for the case of 3D moving objects. Finally, we have used TIE to determine the phase induced in a liquid due to heating by a focused laser beam, which causes self-phase modulation of the beam.

Memarzadeh, S.; Nehmetallah, G. T.; Banerjee, P. P.

2014-06-01

251

3D shape reconstruction from relief calculation: application to human body  

Directory of Open Access Journals (Sweden)

Full Text Available In experimental mechanics especially in experimental biomechanics, evaluating a volume object is a major research axe. In mechanics, 3D reconstruction is made from different optical methods like stereovision [1] or structured light methods. In biomechanics, it is achieved from tomography techniques or from models which divide human body into 15, 16 and 17 polyarticulated solids [2][3]. Those solids are simple volumes (cylinders, spheres. In this review, a method of 3D reconstruction from two calculated relief is proposed. Then, the geometric parameters are extracted using an algorithm and compared to the real dimension of various objects. The first test consist in studying the feasibility of the 3D reconstruction using a real upper arm and a mannequin. In a second test an analysis of a sphere and two cylinders which have different dimensions is performed. The aim of those last tests is to evaluate the performances of the proposed method, to show distortion volume problems and to propose solutions.

Valle V.

2010-06-01

252

Applicator reconstruction in MRI 3D image-based dose planning of brachytherapy for cervical cancer  

DEFF Research Database (Denmark)

BACKGROUND AND PURPOSE: To elaborate a method for applicator reconstruction for MRI-based brachytherapy for cervical cancer. MATERIALS AND METHODS: Custom-made plastic catheters with a copper sulphate solution were made for insertion in the source channels of MR-CT compatible applicators: plastic and titanium tandem ring applicators, and titanium needles. The applicators were CT and MR scanned in a phantom for accurate 3D assessment of applicator visibility and geometry. A reconstruction method was developed and evaluated in 19 patient MR examinations with ring applicator (plastic: 14, titanium: 5). MR applicator reconstruction uncertainties related to inter-observer variation were evaluated. RESULTS: The catheters were visible in the plastic applicator on T1-weighted images in phantom and in 14/14 clinical applications. On T2-weighted images, the catheters appeared weaker but still visible in phantom and in 13/14 MR clinical applications. In the titanium applicator, the catheters could not be separated from the artifacts from the applicator itself. However, these artifacts could be used to localize both titanium ring applicator (5/5 clinical applications) and needles (6/6 clinical applications). Standard deviations of inter-observer differences were below 2mm in all directions. CONCLUSION: 3D applicator reconstruction based on MR imaging could be performed for plastic and titanium applicators. Plastic applicators proved well to be suited for MRI-based reconstruction. For improved practicability of titanium applicator reconstruction, development of MR applicator markers is essential. Reconstruction of titanium applicator and needles at 1.5T MR requires geometric evaluations in phantoms before using the applicator in patients.

Haack, SØren; Nielsen, SØren Kynde

2009-01-01

253

Reconstruction of 3D Human Facial Images Using Partial Differential Equations  

Directory of Open Access Journals (Sweden)

Full Text Available One of the challenging problems in geometric modeling and computer graphics is the construction of realistic human facial geometry. Such geometry are essential for a wide range of applications, such as 3D face recognition, virtual reality applications, facial expression simulation and computer based plastic surgery application. This paper addresses a method for the construction of 3D geometry of human faces based on the use of Elliptic Partial Differential Equations (PDE. Here the geometry corresponding to a human face is treated as a set of surface patches, whereby each surface patch is represented using four boundary curves in the 3-space that formulate the appropriate boundary conditions for the chosen PDE. These boundary curves are extracted automatically using 3D data of human faces obtained using a 3D scanner. The solution of the PDE generates a continuous single surface patch describing the geometry of the original scanned data. In this study, through a number of experimental verifications we have shown the efficiency of the PDE based method for 3D facial surface reconstruction using scan data. In addition to this, we also show that our approach provides an efficient way of facial representation using a small set of parameters that could be utilized for efficient facial data storage and verification purposes.

Eyad Elyan

2007-10-01

254

3D Coronal Density Reconstruction and Retrieving the Magnetic Field Structure during Solar Minimum  

CERN Document Server

Measurement of the coronal magnetic field is a crucial ingredient in understanding the nature of solar coronal phenomena at all scales. We employed STEREO/COR1 data obtained during a deep minimum of solar activity in February 2008 (Carrington rotation CR 2066) to retrieve and analyze the three-dimensional (3D) coronal electron density in the range of heights from 1.5 to 4 Rsun using a tomography method. With this, we qualitatively deduced structures of the coronal magnetic field. The 3D electron density analysis is complemented by the 3D STEREO/EUVI emissivity in the 195 A band obtained by tomography for the same CR. A global 3D MHD model of the solar corona was used to relate the reconstructed 3D density and emissivity to open/closed magnetic field structures. We show that the density maximum locations can serve as an indicator of current sheet position, while the locations of the density gradient maximum can be a reliable indicator of coronal hole boundaries. We find that the magnetic field configuration du...

Kramar, M; Miki?, Z; Davila, J

2014-01-01

255

3D spine reconstruction of postoperative patients from multi-level manifold ensembles.  

Science.gov (United States)

The quantitative assessment of surgical outcomes using personalized anatomical models is an essential task for the treatment of spinal deformities such as adolescent idiopathic scoliosis. However an accurate 3D reconstruction of the spine from postoperative X-ray images remains challenging due to presence of instrumentation (metallic rods and screws) occluding vertebrae on the spine. In this paper, we formulate the reconstruction problem as an optimization over a manifold of articulated spine shapes learned from pathological training data. The manifold itself is represented using a novel data structure, a multi-level manifold ensemble, which contains links between nodes in a single hierarchical structure, as well as links between different hierarchies, representing overlapping partitions. We show that this data structure allows both efficient localization and navigation on the manifold, for on-the-fly building of local nonlinear models (manifold charting). Our reconstruction framework was tested on pre- and postoperative X-ray datasets from patients who underwent spinal surgery. Compared to manual ground-truth, our method achieves a 3D reconstruction accuracy of 2.37 +/- 0.85 mm for postoperative spine models and can deal with severe cases of scoliosis. PMID:25320820

Kadoury, Samuel; Labelle, Hubert; Parent, Stefan

2014-01-01

256

3-D reconstruction of a human fetus with combined holoprosencephaly and cyclopia  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background The purpose of this study was to examine a human fetus with combined holoprosencephaly and cyclopia by means of histology and 3-D reconstruction to determine the internal structure and extent of the malformation. Methods The head from a human fetus at 20 weeks gestation and a diagnosis of holoprosencephaly and cyclopia was investigated histologically and three-dimensionally reconstructed with CAD techniques. The cranial bones, blood vessels, nerves, eye and brain anlagen were reconstructed. Results The 3-D reconstruction revealed both severe malformation and absence of the facial midline bones above the maxilla, and a malformation of the maxilla and sphenoid bone. The mandible, posterior cranial bones, cranial nerves and blood vessels were normal. A synophthalmic eye with two lenses was found. The prosencephalon was a single small protrusion above the diencephalon. No nasal cavity was present. Above the single eye a proboscis was found. Conclusion The absence of the facial midline bones above the maxilla and the presence of a proboscis as a nose-like structure above the cyclopic eye both mean that there was a developmental defect in the fronto-nasal facial process of this fetus.

Meiselbach Veronika

2009-06-01

257

Test of 3D CT reconstructions by EM + TV algorithm from undersampled data  

Energy Technology Data Exchange (ETDEWEB)

Computerized tomography (CT) plays an important role in medical imaging for diagnosis and therapy. However, CT imaging is connected with ionization radiation exposure of patients. Therefore, the dose reduction is an essential issue in CT. In 2011, the Expectation Maximization and Total Variation Based Model for CT Reconstruction (EM+TV) was proposed. This method can reconstruct a better image using less CT projections in comparison with the usual filtered back projection (FBP) technique. Thus, it could significantly reduce the overall dose of radiation in CT. This work reports the results of an independent numerical simulation for cone beam CT geometry with alternative virtual phantoms. As in the original report, the 3D CT images of 128 Multiplication-Sign 128 Multiplication-Sign 128 virtual phantoms were reconstructed. It was not possible to implement phantoms with lager dimensions because of the slowness of code execution even by the CORE i7 CPU.

Evseev, Ivan; Ahmann, Francielle; Silva, Hamilton P. da [Universidade Tecnologica Federal do Parana - UTFPR/FB, 85601-970, Caixa Postal 135, Francisco Beltrao - PR (Brazil); Schelin, Hugo R. [Universidade Tecnologica Federal do Parana-UTFPR/FB,85601-970,Caixa Postal 135,Francisco Beltrao-PR (Brazil) and Faculdades Pequeno Principe-FPP, Av. Iguacu, 333, Rebou (Brazil); Yevseyeva, Olga [Universidade Federal de Santa Catarina - UFSC/ARA, 88900-000, Rua Pedro Joao Pereira, 150, Ararangua - SC (Brazil); Klock, Margio C. L. [Universidade Federal do Parana - UFPR Litoral, 80230-901, Rua Jaguaraiva 512, Caioba, Matinhos - PR (Brazil)

2013-05-06

258

Test of 3D CT reconstructions by EM + TV algorithm from undersampled data  

International Nuclear Information System (INIS)

Computerized tomography (CT) plays an important role in medical imaging for diagnosis and therapy. However, CT imaging is connected with ionization radiation exposure of patients. Therefore, the dose reduction is an essential issue in CT. In 2011, the Expectation Maximization and Total Variation Based Model for CT Reconstruction (EM+TV) was proposed. This method can reconstruct a better image using less CT projections in comparison with the usual filtered back projection (FBP) technique. Thus, it could significantly reduce the overall dose of radiation in CT. This work reports the results of an independent numerical simulation for cone beam CT geometry with alternative virtual phantoms. As in the original report, the 3D CT images of 128×128×128 virtual phantoms were reconstructed. It was not possible to implement phantoms with lager dimensions because of the slowness of code execution even by the CORE i7 CPU.

259

Optical 3D Surface Reconstruction by a Multi-Period Phase Shift Method  

Directory of Open Access Journals (Sweden)

Full Text Available One problem of classical phase shifting for optical 3D surface reconstruction is the occurrence of ambiguities due to the use of fringe projection. We generally derive a number-theoretical approach to calculate absolute phase measurements which can be used as a base for a reliable surface reconstruction without any ambiguity. The essence of our method is the application of pattern sequences with different periods whereby we homogeneously use all pictures which were taken for the measurement. This leads to a higher average accuracy in the surface reconstruction. Furthermore we propose a technique to avoid typical calculation errors that are produced in classical phase shifting caused by discontinuities, occlusions and reflections on the surface.

Erik Lilienblum

2007-04-01

260

Comparative validation of single-shot optical techniques for laparoscopic 3-D surface reconstruction.  

Science.gov (United States)

Intra-operative imaging techniques for obtaining the shape and morphology of soft-tissue surfaces in vivo are a key enabling technology for advanced surgical systems. Different optical techniques for 3-D surface reconstruction in laparoscopy have been proposed, however, so far no quantitative and comparative validation has been performed. Furthermore, robustness of the methods to clinically important factors like smoke or bleeding has not yet been assessed. To address these issues, we have formed a joint international initiative with the aim of validating different state-of-the-art passive and active reconstruction methods in a comparative manner. In this comprehensive in vitro study, we investigated reconstruction accuracy using different organs with various shape and texture and also tested reconstruction robustness with respect to a number of factors like the pose of the endoscope as well as the amount of blood or smoke present in the scene. The study suggests complementary advantages of the different techniques with respect to accuracy, robustness, point density, hardware complexity and computation time. While reconstruction accuracy under ideal conditions was generally high, robustness is a remaining issue to be addressed. Future work should include sensor fusion and in vivo validation studies in a specific clinical context. To trigger further research in surface reconstruction, stereoscopic data of the study will be made publically available at www.open-CAS.com upon publication of the paper. PMID:24876109

Maier-Hein, L; Groch, A; Bartoli, A; Bodenstedt, S; Boissonnat, G; Chang, P-L; Clancy, N T; Elson, D S; Haase, S; Heim, E; Hornegger, J; Jannin, P; Kenngott, H; Kilgus, T; Müller-Stich, B; Oladokun, D; Röhl, S; Dos Santos, T R; Schlemmer, H-P; Seitel, A; Speidel, S; Wagner, M; Stoyanov, D

2014-10-01

 
 
 
 
261

3D reconstruction of internal structure of animal body using near-infrared light  

Science.gov (United States)

To realize three-dimensional (3D) optical imaging of the internal structure of animal body, we have developed a new technique to reconstruct CT images from two-dimensional (2D) transillumination images. In transillumination imaging, the image is blurred due to the strong scattering in the tissue. We had developed a scattering suppression technique using the point spread function (PSF) for a fluorescent light source in the body. In this study, we have newly proposed a technique to apply this PSF for a light source to the image of unknown light-absorbing structure. The effectiveness of the proposed technique was examined in the experiments with a model phantom and a mouse. In the phantom experiment, the absorbers were placed in the tissue-equivalent medium to simulate the light-absorbing organs in mouse body. Near-infrared light was illuminated from one side of the phantom and the image was recorded with CMOS camera from another side. Using the proposed techniques, the scattering effect was efficiently suppressed and the absorbing structure can be visualized in the 2D transillumination image. Using the 2D images obtained in many different orientations, we could reconstruct the 3D image. In the mouse experiment, an anesthetized mouse was held in an acrylic cylindrical holder. We can visualize the internal organs such as kidneys through mouse's abdomen using the proposed technique. The 3D image of the kidneys and a part of the liver were reconstructed. Through these experimental studies, the feasibility of practical 3D imaging of the internal light-absorbing structure of a small animal was verified.

Tran, Trung Nghia; Yamamoto, Kohei; Namita, Takeshi; Kato, Yuji; Shimizu, Koichi

2014-03-01

262

3D reconstruction of digitized histological sections for vasculature quantification in the mouse hind limb  

Science.gov (United States)

In contrast to imaging modalities such as magnetic resonance imaging and micro computed tomography, digital histology reveals multiple stained tissue features at high resolution (0.25?m/pixel). However, the two-dimensional (2D) nature of histology challenges three-dimensional (3D) quantification and visualization of the different tissue components, cellular structures, and subcellular elements. This limitation is particularly relevant to the vasculature, which has a complex and variable structure within tissues. The objective of this study was to perform a fully automated 3D reconstruction of histology tissue in the mouse hind limb preserving the accurate systemic orientation of the tissues, stained with hematoxylin and immunostained for smooth muscle ? actin. We performed a 3D reconstruction using pairwise rigid registrations of 5?m thick, paraffin-embedded serial sections, digitized at 0.25?m/pixel. Each registration was performed using the iterative closest points algorithm on blood vessel landmarks. Landmarks were vessel centroids, determined according to a signed distance map of each pixel to a decision boundary in hue-saturation-value color space; this decision boundary was determined based on manual annotation of a separate training set. Cell nuclei were then automatically extracted and corresponded to refine the vessel landmark registration. Homologous nucleus landmark pairs appearing on not more than two adjacent slides were chosen to avoid registrations which force curved or non-sectionorthogonal structures to be straight and section-orthogonal. The median accumulated target registration errors ± interquartile ranges for the vessel landmark registration, and the nucleus landmark refinement were 43.4+/-42.8?m and 2.9+/-1.7?m, respectively (p<0.0001). Fully automatic and accurate 3D rigid reconstruction of mouse hind limb histology imaging is feasible based on extracted vasculature and nuclei.

Xu, Yiwen; Pickering, J. Geoffrey; Nong, Zengxuan; Gibson, Eli; Ward, Aaron D.

2014-03-01

263

Ion track reconstruction in 3D using alumina-based fluorescent nuclear track detectors  

Science.gov (United States)

Fluorescent nuclear track detectors (FNTDs) based on Al2O3: C, Mg single crystal combined with confocal microscopy provide 3D information on ion tracks with a resolution only limited by light diffraction. FNTDs are also ideal substrates to be coated with cells to engineer cell-fluorescent ion track hybrid detectors (Cell-Fit-HD). This radiobiological tool enables a novel platform linking cell responses to physical dose deposition on a sub-cellular level in proton and heavy ion therapies. To achieve spatial correlation between single ion hits in the cell coating and its biological response the ion traversals have to be reconstructed in 3D using the depth information gained by the FNTD read-out. FNTDs were coated with a confluent human lung adenocarcinoma epithelial (A549) cell layer. Carbon ion irradiation of the hybrid detector was performed perpendicular and angular to the detector surface. In situ imaging of the fluorescently labeled cell layer and the FNTD was performed in a sequential read-out. Making use of the trajectory information provided by the FNTD the accuracy of 3D track reconstruction of single particles traversing the hybrid detector was studied. The accuracy is strongly influenced by the irradiation angle and therefore by complexity of the FNTD signal. Perpendicular irradiation results in highest accuracy with error of smaller than 0.10°. The ability of FNTD technology to provide accurate 3D ion track reconstruction makes it a powerful tool for radiobiological investigations in clinical ion beams, either being used as a substrate to be coated with living tissue or being implanted in vivo.

Niklas, M.; Bartz, J. A.; Akselrod, M. S.; Abollahi, A.; Jäkel, O.; Greilich, S.

2013-09-01

264

Computer-aided interactive surgical simulation for craniofacial anomalies based on 3-D surface reconstruction CT images  

Energy Technology Data Exchange (ETDEWEB)

We developed a computer-aided interactive surgical simulation system for craniofacial anomalies based on three-dimensional (3-D) surface reconstruction CT imaging. This system has four functions: (1) 3-D surface reconstruction display with an accelerated projection method; (2) Surgical simulation to cut, move, rotate, and reverse bone-blocks over the reference 3-D image on the CRT screen; (3) 3-D display of the simulated image in arbitrary views; and (4) Prediction of postoperative skin surface features displayed as 3-D images in arbitrary views. Retrospective surgical simulation has been performed on three patients who underwent the fronto-orbital advancement procedures for brachycephaly and two who underwent the reconstructive procedure for scaphocephaly. The predicted configurations of the cranium and skin surface were well simulated when compared to the postoperative images in 3-D arbitrary views. In practical use, this software might be used for an on-line system connected to a large scale general-purpose computer.

Fujioka, Mutsuhisa; Yokoi, Shigeki; Yasuda, Takami; Hashimoto, Yasuhiro; Toriwaki, Junnichiro; Nakajima, Hideo.

1988-10-01

265

3D MRI findings of anterior cruciate ligament reconstruction at follow-up  

International Nuclear Information System (INIS)

Objective: To investigate the postoperative 3D MRI appearances and their evolvement patterns of ACL grafts and bone tunnels at follow-up. Methods: There were 2,6 double bundles ACL reconstructions and 16 single bundle ACL reconstructions, and a total of 56 follow-up 3D MR Imaging. MR images were reconstructed with MPR technique to evaluate grafts, bone tunnels, fixers and associated complications. Proportions of grafts with hypointensity or hyperintensity and occurrence rates of marrow edema around bone tunnels were calculated respectively among groups of different periods after operation. Results: There were 2, 4 grafts of hypointensity and 32 grafts of hyperintensity. Grafts of 2 cases were suspended with cross pins within femoral tunnels, graft of 1 case was suspended with an endobutton within the femoral tunnel, and grafts of other sites were fixed with interference screws. In the three periods as 3 months, 6 to 9 months and over 12 months after cruciate ligament reconstruction, proportions of hypointensive grafts were 20/25, 0/14 and 4/10 respectively, while proportions of hyperintensive grafts were 5/25, 14/14 and 6/10 respectively, occurrence proportions of marrow edema around bone tunnels were 54/54, 10/32 and 4/26 respectively. There was 1 tear graft, 4 tibial tunnels placed anteriorly with ACL graft impingement on the intercondylar roof, 3 femoral tunnels placed anteriorly, and 2 bone tunnels with mismatching interference screws. Conclusion: 3D MRI can accurately demonstrate the state of ACL grafts, bone tunnels, fixers and associated complications. Intensity of grafts presented a rise and reduce pattern after operation. (authors)

266

Regularization approach for tomosynthesis X-ray inspection  

International Nuclear Information System (INIS)

X-ray inspection is intended to be used as an escalation technique for inspection of carbon fiber reinforced plastics (CFRP) in aerospace applications, especially in case of unclear indications from ultrasonic or other NDT modalities. Due to their large dimensions, most aerospace components cannot be scanned by conventional computed tomography. In such cases, X-ray Laminography may be applied, allowing a pseudo 3D slice-by-slice reconstruction of the sample with Tomosynthesis. However, due to the limited angle acquisition geometry, reconstruction artifacts arise, especially at surfaces parallel to the imaging plane. To regularize the Tomosynthesis approach, we propose an additional prescan of the object to detect outer sample surfaces. We recommend the use of contrasted markers which are temporarily attached to the sample surfaces. The depth position of the markers is then derived from that prescan. As long as the sample surface remains simple, few markers are required to fit the respective object surfaces. The knowledge about this surface may then be used to regularize the final Tomosynthesis reconstruction, performed with markerless projections. Eventually, it can also serve as prior information for an ART reconstruction or to register a CAD model of the sample. The presented work is carried out within the European FP7 project QUICOM. We demonstrate the proposed approach within a simulation study applying an acquisition geometry suited for CFRP part inspection. A practical verification of the approach is planned later in the project

267

Regularization approach for tomosynthesis X-ray inspection  

Energy Technology Data Exchange (ETDEWEB)

X-ray inspection is intended to be used as an escalation technique for inspection of carbon fiber reinforced plastics (CFRP) in aerospace applications, especially in case of unclear indications from ultrasonic or other NDT modalities. Due to their large dimensions, most aerospace components cannot be scanned by conventional computed tomography. In such cases, X-ray Laminography may be applied, allowing a pseudo 3D slice-by-slice reconstruction of the sample with Tomosynthesis. However, due to the limited angle acquisition geometry, reconstruction artifacts arise, especially at surfaces parallel to the imaging plane. To regularize the Tomosynthesis approach, we propose an additional prescan of the object to detect outer sample surfaces. We recommend the use of contrasted markers which are temporarily attached to the sample surfaces. The depth position of the markers is then derived from that prescan. As long as the sample surface remains simple, few markers are required to fit the respective object surfaces. The knowledge about this surface may then be used to regularize the final Tomosynthesis reconstruction, performed with markerless projections. Eventually, it can also serve as prior information for an ART reconstruction or to register a CAD model of the sample. The presented work is carried out within the European FP7 project QUICOM. We demonstrate the proposed approach within a simulation study applying an acquisition geometry suited for CFRP part inspection. A practical verification of the approach is planned later in the project.

Tigkos, Konstantinos; Hassler, Ulf; Holub, Wolfgang; Woerlein, Norbert; Rehak, Markus [Fraunhofer Development Center X-ray Technologies (EZRT), Dept. Application Specific Methods and Systems (AMS), Fraunhofer IIS, Flugplatzstraße 75, 90768 Fürth (Germany)

2014-02-18

268

Regularization approach for tomosynthesis X-ray inspection  

Science.gov (United States)

X-ray inspection is intended to be used as an escalation technique for inspection of carbon fiber reinforced plastics (CFRP) in aerospace applications, especially in case of unclear indications from ultrasonic or other NDT modalities. Due to their large dimensions, most aerospace components cannot be scanned by conventional computed tomography. In such cases, X-ray Laminography may be applied, allowing a pseudo 3D slice-by-slice reconstruction of the sample with Tomosynthesis. However, due to the limited angle acquisition geometry, reconstruction artifacts arise, especially at surfaces parallel to the imaging plane. To regularize the Tomosynthesis approach, we propose an additional prescan of the object to detect outer sample surfaces. We recommend the use of contrasted markers which are temporarily attached to the sample surfaces. The depth position of the markers is then derived from that prescan. As long as the sample surface remains simple, few markers are required to fit the respective object surfaces. The knowledge about this surface may then be used to regularize the final Tomosynthesis reconstruction, performed with markerless projections. Eventually, it can also serve as prior information for an ART reconstruction or to register a CAD model of the sample. The presented work is carried out within the European FP7 project QUICOM. We demonstrate the proposed approach within a simulation study applying an acquisition geometry suited for CFRP part inspection. A practical verification of the approach is planned later in the project.

Tigkos, Konstantinos; Hassler, Ulf; Holub, Wolfgang; Woerlein, Norbert; Rehak, Markus

2014-02-01

269

3D shape reconstruction of bone from two x-ray images using 2D/3D non-rigid registration based on moving least-squares deformation  

Science.gov (United States)

Several studies based on biplanar radiography technologies are foreseen as great systems for 3D-reconstruction applications for medical diagnoses. This paper proposes a non-rigid registration method to estimate a 3D personalized shape of bone models from two planar x-ray images using an as-rigid-as-possible deformation approach based on a moving least-squares optimization method. Based on interactive deformation methods, the proposed technique has the ability to let a user improve readily and with simplicity a 3D reconstruction which is an important step in clinical applications. Experimental evaluations of six anatomical femur specimens demonstrate good performances of the proposed approach in terms of accuracy and robustness when compared to CT-scan.

Cresson, T.; Branchaud, D.; Chav, R.; Godbout, B.; de Guise, J. A.

2010-03-01

270

Active illumination based 3D surface reconstruction and registration for image guided medialization laryngoplasty  

Science.gov (United States)

The medialization laryngoplasty is a surgical procedure to improve the voice function of the patient with vocal fold paresis and paralysis. An image guided system for the medialization laryngoplasty will help the surgeons to accurately place the implant and thus reduce the failure rates of the surgery. One of the fundamental challenges in image guided system is to accurately register the preoperative radiological data to the intraoperative anatomical structure of the patient. In this paper, we present a combined surface and fiducial based registration method to register the preoperative 3D CT data to the intraoperative surface of larynx. To accurately model the exposed surface area, a structured light based stereo vision technique is used for the surface reconstruction. We combined the gray code pattern and multi-line shifting to generate the intraoperative surface of the larynx. To register the point clouds from the intraoperative stage to the preoperative 3D CT data, a shape priori based ICP method is proposed to quickly register the two surfaces. The proposed approach is capable of tracking the fiducial markers and reconstructing the surface of larynx with no damage to the anatomical structure. We used off-the-shelf digital cameras, LCD projector and rapid 3D prototyper to develop our experimental system. The final RMS error in the registration is less than 1mm.

Jin, Ge; Lee, Sang-Joon; Hahn, James K.; Bielamowicz, Steven; Mittal, Rajat; Walsh, Raymond

2007-03-01

271

A parallel algorithm for 3D particle tracking and Lagrangian trajectory reconstruction  

Science.gov (United States)

Particle-tracking methods are widely used in fluid mechanics and multi-target tracking research because of their unique ability to reconstruct long trajectories with high spatial and temporal resolution. Researchers have recently demonstrated 3D tracking of several objects in real time, but as the number of objects is increased, real-time tracking becomes impossible due to data transfer and processing bottlenecks. This problem may be solved by using parallel processing. In this paper, a parallel-processing framework has been developed based on frame decomposition and is programmed using the asynchronous object-oriented Charm++ paradigm. This framework can be a key step in achieving a scalable Lagrangian measurement system for particle-tracking velocimetry and may lead to real-time measurement capabilities. The parallel tracking algorithm was evaluated with three data sets including the particle image velocimetry standard 3D images data set #352, a uniform data set for optimal parallel performance and a computational-fluid-dynamics-generated non-uniform data set to test trajectory reconstruction accuracy, consistency with the sequential version and scalability to more than 500 processors. The algorithm showed strong scaling up to 512 processors and no inherent limits of scalability were seen. Ultimately, up to a 200-fold speedup is observed compared to the serial algorithm when 256 processors were used. The parallel algorithm is adaptable and could be easily modified to use any sequential tracking algorithm, which inputs frames of 3D particle location data and outputs particle trajectories.

Barker, Douglas; Lifflander, Jonathan; Arya, Anshu; Zhang, Yuanhui

2012-02-01

272

Maxillary sinus 3D segmentation and reconstruction from cone beam CT data sets  

Energy Technology Data Exchange (ETDEWEB)

Purpose: Segmentation of the maxillary sinuses for three-dimensional (3D) reconstruction, visualization and volumetry is sought using an automated algorithm applied to cone beam computed tomographic (CBCT) data sets. Materials and methods: Cone beam computed tomography (CBCT) data sets of three subjects aged 9, 17, and 27 were used in 3D segmentation and reconstruction. The maxillary sinuses were obtained by propagation from one start point in the right sinus and one start point in the left sinus to the whole regions of both sinuses. The procedure was based on voxel intensity distributions and common anatomic structures, specifically each middle meatus of the nasal cavity. A program was written in C++ and VTK languages to demonstrate the surface topological shapes of the maxillary sinuses. Results: The developed segmentation algorithm separated maxillary sinuses successfully permitting accurate comparisons. It was robust and efficient. 3D morphological features of the maxillary sinuses were observed from three human subjects. Conclusions: Automated segmentation of maxillary sinuses from CBCT data sets is feasible using the proposed method. This tool might be useful for visualization, pathological diagnosis, and treatment planning of maxillary sinus disorders. (orig.)

Shi, Hongjian [Louisville Univ., KY (United States). Computer Vision and Image Processing Lab.; Scarfe, W.C.; Farman, A.G. [Louisville Univ., KY (United States). Div. of Radiology and Imaging Science

2006-08-15

273

Object-shape recognition and 3D reconstruction from tactile sensor images.  

Science.gov (United States)

This article presents a novel approach of edged and edgeless object-shape recognition and 3D reconstruction from gradient-based analysis of tactile images. We recognize an object's shape by visualizing a surface topology in our mind while grasping the object in our palm and also taking help from our past experience of exploring similar kind of objects. The proposed hybrid recognition strategy works in similar way in two stages. In the first stage, conventional object-shape recognition using linear support vector machine classifier is performed where regional descriptors features have been extracted from the tactile image. A 3D shape reconstruction is also performed depending upon the edged or edgeless objects classified from the tactile images. In the second stage, the hybrid recognition scheme utilizes the feature set comprising both the previously obtained regional descriptors features and some gradient-related information from the reconstructed object-shape image for the final recognition in corresponding four classes of objects viz. planar, one-edged object, two-edged object and cylindrical objects. The hybrid strategy achieves 97.62 % classification accuracy, while the conventional recognition scheme reaches only to 92.60 %. Moreover, the proposed algorithm has been proved to be less noise prone and more statistically robust. PMID:24469960

Khasnobish, Anwesha; Singh, Garima; Jati, Arindam; Konar, Amit; Tibarewala, D N

2014-04-01

274

3D Reconstruction: Novel Method for Finding of Corresponding Points using Pseudo Colors  

Directory of Open Access Journals (Sweden)

Full Text Available This paper deals with the reconstruction of spatial coordinates of an arbitrary point in a scene using two images scanned by a 3D camera or two displaced cameras. Calculations are based on the perspective geom-etry. Accurate determination of corresponding points is a fundamental step in this process. The usually used methods can have a problem with points, which lie in areas without sufficient contrast. This paper describes our proposed method based on the use of the relationship between the selected points and area feature points. The proposed method finds correspondence using a set of feature points found by SURF. An algorithm is proposed and described for quick removal of false correspondences, which could ruin the correct reconstruction. The new method, which makes use of pseudo color image representation (pseudo coloring has been proposed subsequently. By means of this method it is possible to significantly increase the color contrast of the surveyed image, and therefore add more information to find the correct correspondence. Reliability of the found correspondence can be verified by reconstruction of 3D position of selected points. Executed experiments confirm our assumptions

L. Bolecek

2013-04-01

275

Automatic urban 3D building reconstruction from multi-ray photogrammetry  

Science.gov (United States)

Over the last 20 years the use of, and demand for, three dimensional (3D) building models has meant there has been a vast amount of research conducted in automating the extraction and reconstruction of these models from airborne sensors. Whilst many different approaches have been suggested, full automation is yet to be achieved and research has suggested that the combination of data from multiple sources is required in order to achieve this. Developments in digital photogrammetry have delivered improvements in spatial resolution whilst higher image overlap to increase the number of pixel correspondents between images, giving the name multi-ray photogrammetry, has improved the resolution and quality of its by-products. In this paper the extraction of roof geometry from multiray photogrammetry will be covered, which underpins 3D building reconstruction. Using orthophotos, roof vertices are extracted using the Canny edge detector. Roof planes are detected from digital surface models (DSM) by extracting information from 2D cross sections and measuring height differences. To eliminate overhanging vegetation, the segmentation of trees is investigated by calculating the characteristics of a point within a local neighbourhood of the photogrammetric point cloud. The results highlight the complementary nature of these information sources, and a methodology for integration and reconstruction of roof geometry is proposed.

McClune, A. P.; Miller, P. E.; Mills, J. P.; Holland, D.

2014-08-01

276

Algorithm for Reconstruction of 3D Molecular Structure from Diffraction Patterns of Laser-Aligned Molecules  

Science.gov (United States)

Ultrafast electron diffraction from laser-aligned gas molecules is a promising method for the determination of 3D molecular structures. Reconstruction algorithms for diffraction patterns of perfectly aligned molecules have been widely studied theoretically. However, under experimental conditions only partial alignment can be achieved and the existing algorithms do not perform well when the alignment is not perfect. We develop a method to reconstruct the 3D structure of molecules with cylindrical symmetry from electron diffraction patterns of partially-aligned molecules. The evolutionary algorithm assumes a known angular distribution, which can be calculated numerically using existing theory for laser-alignment and verified by comparison with the data. Selecting CF3I as the cylindrically symmetric molecule, diffraction patterns from multiple alignment angles are used to reconstruct a single diffraction pattern corresponding to perfect alignment. The molecular structure can then be recovered from this pattern with no prior structural information required. Our results are in good agreement with previous models of CF3I structure.

Yang, Jie; Hensley, Christopher; Centurion, Martin

2012-06-01

277

3D Equilibrium Reconstruction with Improved Magnetic Diagnostics on the Compact Toroidal Hybrid  

Science.gov (United States)

Three-dimensional reconstruction of plasma equilibria is important for understanding the physics of both intrinsic 3D confinement in stellarators as well as axisymmetric plasmas in tokamaks. Equilibrium reconstructions using the V3FIT code [1] will be presented for current carrying plasma on the Compact Toroidal Hybrid (CTH) torsatron experiment. The CTH is a heliotron-type device, in which the magnetic configuration can be strongly modified by an ohmically-driven plasma current. These reconstructions use sets of recently upgraded magnetic diagnostics (44 channels), including segment and full Rogowski coils and new saddle coils. Reconstruction results with these new diagnostics, especially the time evolution of the reconstructed current density profile for a series of plasma conditions, will be presented and compared to previous ones using a smaller set of input magnetic signals. New modelling of the effects of eddy currents in the helical coil frame and vacuum vessel will also be discussed.[4pt] [1] J. D. Hanson, S. P. Hirshman, S. F. Knowlton, L. L. Lao, E. A. Lazarus, J. M. Shields, Nucl, Fusion49, 075031 (2009)

Ma, X.; Hanson, J. D.; Hartwell, G. J.; Knowlton, S. F.; Maurer, D. A.

2012-10-01

278

Track reconstruction using a 3-D map of the target magnetic field  

International Nuclear Information System (INIS)

Magnetic fields are often applied to the target zone of a particle beam to maintain the polarization of gaseous targets, as with the HERMES experiment. The same field bends the trajectories of charged particles, however, introducing errors in vertex reconstruction. This paper describes a method for accurately describing relativistic charged particle transport within a 3-dimensional (3-D), non-uniform magnetic field. The algorithm is tested on HERMES experimental data, and is shown to substantially improve the Ks0 resonance in the ?+?- invariant mass spectrum. Indeed, corrected data taken with target magnet switched on are as good as data taken with magnet switched off. The method can easily be applied to other experiments given a 3-D magnetic field map of the target region. The relevant code is provided in an Appendix.

279

Quantitative roughness characterization and 3D reconstruction of electrode surface using cyclic voltammetry and SEM image  

Science.gov (United States)

Area measurements from cyclic voltammetry (CV) and image from scanning electron microscopy (SEM) are used to characterize electrode statistical morphology, 3D surface reconstruction and its electroactivity. SEM images of single phased materials correspond to two-dimensional (2D) projections of 3D structures, leading to an incomplete characterization. Lack of third dimension information in SEM image is circumvented using equivalence between denoised SEM image and CV area measurements. This CV-SEM method can be used to estimate power spectral density (PSD), width, gradient, finite fractal nature of roughness and local morphology of the electrode. We show that the surface morphological statistical property like distribution function of gradient can be related to local electro-activity. Electrode surface gradient micrographs generated here can provide map of electro-activity sites. Finally, the densely and uniformly packed small gradient over the Pt-surface is the determining criterion for high intrinsic electrode activity.

Dhillon, Shweta; Kant, Rama

2013-10-01

280

3D Reconstruction of Coronal Loops by the Principal Component Analysis  

Directory of Open Access Journals (Sweden)

Full Text Available Knowing the three dimensional structure of plasma filaments in the uppermost part of the solar atmosphere, known as coronal loops, and especially their length, is an important parameter in the wave-based diagnostics of this part of the Sun. The combination of observations of the Sun from different points of observations in space, thanks to the most recent missions, including the Solar Dynamics Observatory (SDO and the Solar TErrestrial RElations Observatory (STEREO, allows us to infer information about the geometrical shape of coronal loops in 3D space. Here, we propose a new method to reconstruct the loop shape starting from stereoscopically determined 3D points, which sample the loop length, by principal component analysis. This method is shown to retrieve in an easy way the main parameters that define the loop, e.g., the minor and major axes, the loop plane, the azimuthal and inclination angles, for the special case of a coplanar loop.

Erwin Verwichte

2013-10-01

 
 
 
 
281

Robust affine-invariant feature points matching for 3D surface reconstruction of complex landslide scenes  

Science.gov (United States)

Multi-view stereo surface reconstruction from dense terrestrial photographs is being increasingly applied for geoscience applications such as quantitative geomorphology, and a number of different software solution and processing streamlines have been suggested. For image matching, camera self-calibration and bundle block adjustment, most approaches make use of scale-invariant feature transform (SIFT) to identify homologous points in multiple images. SIFT-like point matching is robust to apparent translation, rotation, and scaling of objects in multiple viewing geometries but the number of correctly identified matching points typically declines drastically with increasing angles between the viewpoints. For the application of multi-view stereo of complex landslide scenes, the viewing geometry is often constrained by the local topography and barriers such as rocks and vegetation occluding the target. Under such conditions it is not uncommon to encounter view angle differences of > 30% that hinder the image matching and eventually prohibit the joint estimation of the camera parameters from all views. Recently an affine invariant extension of the SIFT detector (ASIFT) has been demonstrated to provide more robust matches when large view-angle differences become an issue. In this study the ASIFT detector was adopted to detect homologous points in terrestrial photographs preceding 3D reconstruction of different parts (main scarp, toe) of the Super-Sauze landslide (Southern French Alps). 3D surface models for different time periods and different parts of the landslide were derived using the multi-view stereo framework implemented in MicMac (©IGN). The obtained 3D models were compared with reconstructions using the traditional SIFT detectors as well as alternative structure-from-motion implementations. An estimate of the absolute accuracy of the photogrammetric models was obtained through co-registration and comparison with high-resolution terrestrial LiDAR scans.

Stumpf, André; Malet, Jean-Philippe; Allemand, Pascal; Skupinski, Grzegorz; Deseilligny, Marc-Pierrot

2013-04-01

282

Fast 3D-EM reconstruction using Planograms for stationary planar positron emission mammography camera.  

Science.gov (United States)

At the University of Pisa we are building a PEM prototype, the YAP-PEM camera, consisting of two opposite 6 x 6 x 3 cm3 detector heads of 30 x 30 YAP:Ce finger crystals, 2 x 2 x 30 mm3 each. The camera will be equipped with breast compressors. The acquisition will be stationary. Compared with a whole body PET scanner, a planar Positron Emission Mammography (PEM) camera allows a better, easier and more flexible positioning around the breast in the vicinity of the tumor: this increases the sensitivity and solid angle coverage, and reduces cost. To avoid software rejection of data during the reconstruction, resulting in a reduced sensitivity, we adopted a 3D-EM reconstruction which uses all of the collected Lines Of Response (LORs). This skips the PSF distortion given by data rebinning procedures and/or Fourier methods. The traditional 3D-EM reconstruction requires several times the computation of the LOR-voxel correlation matrix, or probability matrix {p(ij)}; therefore is highly time-consuming. We use the sparse and symmetry properties of the matrix {p(ij)} to perform fast 3D-EM reconstruction. Geometrically, a 3D grid of cubic voxels (FOV) is crossed by several divergent 3D line sets (LORs). The symmetries occur when tracing different LORs produces the same p(ij) value. Parallel LORs of different sets cross the FOV in the same way, and the repetition of p(ij) values depends on the ratio between the tube and voxel sizes. By optimizing this ratio, the occurrence of symmetries is increased. We identify a nucleus of symmetry of LORs: for each set of symmetrical LORs we choose just one LOR to be put in the nucleus, while the others lie outside. All of the possible p(ij) values are obtainable by tracking only the LORs of this nucleus. The coordinates of the voxels of all of the other LORs are given by means of simple translation rules. Before making the reconstruction, we trace the LORs of the nucleus to find the intersecting voxels, whose p(ij) values are computed and stored with their voxel coordinates on a hard disk. Only the non-zero p(ij) are considered and their computation is performed just once. During the reconstruction, the stored values are loaded and are available in the random access memory for all of the operations of normalization, backprojection and projection: these are now performed rapidly, because the application of the translation rules is much faster than the probability computations. We tested the algorithm on Monte Carlo data fully simulating the typical YAP-PEM clinical condition. The adopted algorithm gives an excellent positioning capability for hot spots in the camera FOV. To use all of the possible skew LORs in the FOV avoids the software rejection of collected data. Reconstructed images indicate that a 5mm diameter tumor of 37 kBq/cm3, in an active breast with a 10:1 Tissue to Background ratio (T/B), with a 10 min acquisition, for a head distance of 5 cm, can be detected by the YAP-PEM with a SNR of 8.7+/-1.0. The obtained SNR values depend linearly on the tumor volume. The algorithm allows one to discriminate between two hot sources of 5.0 mm diameter if they do not lie on the same axis. The YAP-PEM is now in the assembly stage. PMID:16290284

Motta, A; Guerra, A Del; Belcari, N; Moehrs, S; Panetta, D; Righi, S; Valentini, D

2005-12-01

283

Cryptotomography: Reconstructing 3D Fourier Intensities from Randomly Oriented Single-Shot Diffraction Patterns  

International Nuclear Information System (INIS)

We reconstructed the 3D Fourier intensity distribution of monodisperse prolate nanoparticles using single-shot 2D coherent diffraction patterns collected at DESY's FLASH facility when a bright, coherent, ultrafast x-ray pulse intercepted individual particles of random, unmeasured orientations. This first experimental demonstration of cryptotomography extended the expansion-maximization-compression framework to accommodate unmeasured fluctuations in photon fluence and loss of data due to saturation or background scatter. This work is an important step towards realizing single-shot diffraction imaging of single biomolecules.

284

Complex cloacal malformations: use of rotational fluoroscopy and 3-D reconstruction in diagnosis and surgical planning.  

Science.gov (United States)

A cloacal malformation is a congenital malformation in which the urinary tract, gynecological system and distal rectum fail to separate and form a common channel with a single perineal opening. Precise anatomical information is required to plan surgery and predict prognosis for children with this abnormality. Conventional fluoroscopic studies provide limited information, primarily due to the overlap of structures and inability to make accurate measurements. Rotational fluoroscopy and 3-D reconstruction help clarify overlapping structures and allow for precise measurement of the common channel, thereby helping to predict the complexity of the surgical case as well as the long-term prognosis regarding bowel, bladder and sexual function. PMID:22072072

Patel, Manish N; Racadio, John M; Levitt, Marc A; Bischoff, Andrea; Racadio, Judy M; Peña, Alberto

2012-03-01

285

3D CAD model reconstruction of a human femur from MRI images  

Directory of Open Access Journals (Sweden)

Full Text Available Medical practice and life sciences take full advantage of progress in engineering disciplines, in particular the computer assisted placement technique in hip surgery. This paper describes the three dimensional model reconstruction of human femur from MRI images. The developed program enables to obtain digital shape of 3D femur recognized by all CAD software and allows an accurate placement of the femoral component. This technic provides precise measurement of implant alignment during hip resurfacing or total hip arthroplasty, thereby reducing the risk of component mal-positioning and femoral neck notching.

Benaissa EL FAHIME

2013-05-01

286

3D object reconstruction from Swissranger sensor data using a spring-mass model  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We register close-range depth images of objects using a Swissranger sensor and apply a spring-mass model for 3D object reconstruction. The Swissranger sensor delivers depth images in real time which have, compared with other types of sensors, such as laser scanners, a lower resolution and are af?icted with larger uncertainties. To reduce noise and remove outliers in the data, we treat the point cloud as a system of interacting masses connected via elastic forces. We investigate two models, ...

Dellen, Babette; Alenya?, Guillem; Foix, Sergi; Torras, Carme

2009-01-01

287

Applications of 3-D reconstruction and 3-D image analysis using computer graphics in surgery of the oral and maxillofacial regions  

International Nuclear Information System (INIS)

Using the 2-D data provided by CT-Tomography and MRI-tomography of oral and maxillofacial diseases (cyst, benign tumor, primary tumor and regional lymphnodes of malignant tumor), 3-D images were reconstructed and spatial analysis was attempted. We report the general concepts. The hardware used consisted of the Hewlett-Packard HP-9000/300, which utilizes a 16-bit CPU. A digitizer was used to construct 3-D images from serial CT-tomography and MRI-tomography images. Output was displayed on a color monitor and photographs. The 3 cases on which we used this technique included a 19-year-old male with plunging ranula, a 50-year-old male with maxillary pleomorphic adenoma, and a 58-year-old male with squamous cell carcinoma of the maxillary sinus (T3N3M0). As 3-D reconstruction can be done in any arbitrary direction or cross section, it is possible to spatially determine the position of the disease inside the body, its progression, and its relationship with adjacent organs. Through image analysis, it is possible to better understand the volume and surface area of the disease. 3-D image reconstruction is an effective tool in the determination of diagnosis, therapeutic guidelines, and surgical indications, as well as effectiveness of treatment. (author)

288

Simulation and reconstruction of photon patterns in the PANDA 3D Disc DIRC  

International Nuclear Information System (INIS)

The PANDA Disc DIRC is a novel type of Cherenkov detector, being developed to improve the charged particle identification of the upcoming PANDA experiment at the future FAIR facility. The detector has to cover the endcap region of the target spectrometer, resulting in a geometry that by now has never been applied to a DIRC detector. Additional complications are implied by tight space constraints at the foreseen position, interaction rates of 20 MHz up to 50 MHz and the experiments trigger-less readout scheme. To cope with the lack of experience, the development of detector concepts is driven by the development of computer simulations and dedicated reconstruction methods. The performance analysis of a preceding detector concept, presented at the DIRC workshop in 2009, showed several weaknesses which have been eliminated by revising the detector design. This publication summarizes the current status of the software, the reconstruction method and resulting detector performance of the improved design: the PANDA 3D Disc DIRC.

289

Reconstruction of 3D refractive index profiles of PM PANDA optical fiber using digital holographic method  

Science.gov (United States)

In this paper, the refractive indices distributions on the two birefringent axes of polarization maintaining (PM) PANDA type optical fiber are reconstructed. The local refraction of the incident rays crossing the PM optical fiber is considered. Off-axis digital holographic interferometric phase shifting arrangement is employed in this investigation. The recorded mutual phase shifted holograms, starts with 0° with steps of ?/4, are combined and numerically reconstructed in the image plane to obtain the optical interference phase map. Consequently, the optical phase differences due to the PM optical fiber are extracted after unwrapping and background subtraction of the enhanced optical interference phase map. The birefringence and the beat length in the two directions, fast and slow axes of PM optical fiber, of polarizations in the core region are calculated. This holographic technique and the advanced analysis of the phase shifting permit the calculation of the 3D refractive index distributions for PM PANDA optical fiber.

Wahba, H. H.

2014-10-01

290

3D-OSEM iterative image reconstruction for high-resolution PET using precalculated system matrix  

International Nuclear Information System (INIS)

An efficient iterative image reconstruction methodology is presented, adapted to high-resolution flat-head 3D positron emission tomography cameras. It is based on the ordered subsets expectation maximization algorithm and applies to systems with axial symmetry. The associated system matrix is calculated off-line, including a model of the ?-event detection in the crystal, taking into account photoelectric effect and Compton scattering interactions. The nonzero elements of the sparse system matrix are stored in disc in an efficient way that allows the fast sequential access to the matrix elements during the reconstruction. A detailed calculation is performed for the voxels corresponding to central plane within the field of view (FOV) of the camera and the remaining values of the system matrix are obtained via translations based on the symmetries of the system along the axial dimension. GATE-based simulations have been used for the validation of the results

291

Nonintrusive 3D reconstruction of human bone models to simulate their bio-mechanical response  

Science.gov (United States)

3D finite element models representing functional parts of the human skeletal system, have been repeatedly introduced over the last years, to simulate biomechanical response of anatomical characteristics or investigate surgical treatment. The reconstruction of geometrically accurate FEM models, poses a significant challenge for engineers and physicians, as recent advances in tissue engineering dictate highly customized implants, while facilitating the production of alloplast materials that are employed to restore, replace or supplement the function of human tissue. The premises of every accurate reconstruction method, is to encapture the precise geometrical characteristics of the examined tissue and thus the selection of a sufficient imaging technique is of the up-most importance. This paper reviews existing and potential applications related to the current state-of-the-art of medical imaging and simulation techniques. The procedures are examined by introducing their concepts; strengths and limitations, while the authors also present part of their recent activities in these areas. [Figure not available: see fulltext.

Alexander, Tsouknidas; Antonis, Lontos; Savvas, Savvakis; Nikolaos, Michailidis

2012-06-01

292

High resolution 3D image reconstruction in laminar optical tomography based on compressive sensing  

Science.gov (United States)

Laminar optical tomography (LOT) combines the advantages of diffuse optical tomography image reconstruction and a microscopy-based setup to allow non-contact imaging at depth up to a few millimeters. However, LOT image reconstruction paradigm is inherently an ill-posed and computationally expensive inverse problem. Herein, we cast the LOT inverse problem in the compressive sensing (CS) framework to exploit the sparsity of the fluorophore yield in the image domain and to address the ill-posedness of the LOT inverse problem. We apply this new approach to thick tissue engineering applications. We demonstrate the enhanced resolution of our method in 3-D numerical simulations of anatomically accurate microvasculature and using real data obtained from phantom experiments. Furthermore, CS is shown to be more robust against the reduction of measurements in comparison to the classic methods for such application. Potential benefits and shortcomings of the CS approach in the context of LOT are discussed.

Yang, Fugang; Ozturk, Mehmet S.; Cong, Wenxiang; Wang, Ge; Intes, Xavier

2014-02-01

293

Improved 3D reconstruction in smart-room environments using ToF imaging  

DEFF Research Database (Denmark)

This paper presents the use of Time-of-Flight (ToF) cameras in smart-rooms and how this leads to improved results in segmenting the people in the room from the background and consequently better 3D reconstruction of foreground objects. A calibrated rig consisting of one Swissranger SR3100 Time-of-Flight range camera and a high resolution standard CCD camera is set in a smart-room containing five other standard cameras. A probabilistic background model is used to segment each view and a shape from silhouette volume is reconstructed. It is shown that the presence of the range camera gives ways of eliminating regional artifacts and therefore creating a more robust input for higher level applications such as people tracking or human motion analysis.

Guðmundsson, Sigurjón Árni; Aanæs, Henrik

2010-01-01

294

Response to "Feasibility of 3D reconstruction from a single 2D diffraction measurement"  

CERN Document Server

We present our response to Pierre Thibault's article, titled "Feasibility of 3D reconstruction from a single 2D diffraction measurement" [1], in which he commented upon our recent ankylography paper [2]. While we appreciate Thibault's efforts in promoting further reflection on our paper, we found serious errors both in his understanding and analysis of ankylography: he inaccurately presented the oversampling scheme in ankylography, incorrectly described our reconstruction algorithm and our experiment, and formulated arguments based upon a flawed and overly-restrictive theoretical analysis. Therefore, we conclude that his main claims are either scientifically invalid or a misrepresentation of our claims about ankylography. Below is our detailed point-by-point response to his criticisms.

Miao, Jianwei

2009-01-01

295

GPS tomography: validation of reconstructed 3-D humidity fields with radiosonde profiles  

Directory of Open Access Journals (Sweden)

Full Text Available Water vapor plays an important role in meteorological applications; GeoForschungsZentrum (GFZ therefore developed a tomographic system to derive 3-D distributions of the tropospheric water vapor above Germany using GPS data from about 300 ground stations. Input data for the tomographic reconstructions are generated by the Earth Parameter and Orbit determination System (EPOS software of the GFZ, which provides zenith total delay (ZTD, integrated water vapor (IWV and slant total delay (STD data operationally with a temporal resolution of 2.5 min (STD and 15 min (ZTD, IWV. The water vapor distribution in the atmosphere is derived by tomographic reconstruction techniques. The quality of the solution is dependent on many factors such as the spatial coverage of the atmosphere with slant paths, the spatial distribution of their intersections and the accuracy of the input observations. Independent observations are required to validate the tomographic reconstructions and to get precise information on the accuracy of the derived 3-D water vapor fields. To determine the quality of the GPS tomography, more than 8000 vertical water vapor profiles at 13 German radiosonde stations were used for the comparison. The radiosondes were launched twice a day (at 00:00 UTC and 12:00 UTC in 2007. In this paper, parameters of the entire profiles such as the wet refractivity, and the zenith wet delay have been compared. Before the validation the temporal and spatial distribution of the slant paths, serving as a basis for tomographic reconstruction, as well as their angular distribution were studied. The mean wet refractivity differences between tomography and radiosonde data for all points vary from ?1.3 to 0.3, and the root mean square is within the range of 6.5–9. About 32% of 6803 profiles match well, 23% match badly and 45% are difficult to classify as they match only in parts.

M. Shangguan

2013-09-01

296

GPS tomography. Validation of reconstructed 3-D humidity fields with radiosonde profiles  

Energy Technology Data Exchange (ETDEWEB)

Water vapor plays an important role in meteorological applications; GeoForschungsZentrum (GFZ) therefore developed a tomographic system to derive 3-D distributions of the tropospheric water vapor above Germany using GPS data from about 300 ground stations. Input data for the tomographic reconstructions are generated by the Earth Parameter and Orbit determination System (EPOS) software of the GFZ, which provides zenith total delay (ZTD), integrated water vapor (IWV) and slant total delay (STD) data operationally with a temporal resolution of 2.5 min (STD) and 15 min (ZTD, IWV). The water vapor distribution in the atmosphere is derived by tomographic reconstruction techniques. The quality of the solution is dependent on many factors such as the spatial coverage of the atmosphere with slant paths, the spatial distribution of their intersections and the accuracy of the input observations. Independent observations are required to validate the tomographic reconstructions and to get precise information on the accuracy of the derived 3-D water vapor fields. To determine the quality of the GPS tomography, more than 8000 vertical water vapor profiles at 13 German radiosonde stations were used for the comparison. The radiosondes were launched twice a day (at 00:00 UTC and 12:00 UTC) in 2007. In this paper, parameters of the entire profiles such as the wet refractivity, and the zenith wet delay have been compared. Before the validation the temporal and spatial distribution of the slant paths, serving as a basis for tomographic reconstruction, as well as their angular distribution were studied. The mean wet refractivity differences between tomography and radiosonde data for all points vary from -1.3 to 0.3, and the root mean square is within the range of 6.5-9. About 32% of 6803 profiles match well, 23% match badly and 45% are difficult to classify as they match only in parts.

Shangguan, M.; Bender, M.; Ramatschi, M.; Dick, G.; Wickert, J. [Helmholtz Centre Potsdam, German Research Centre for Geosciences (GFZ), Potsdam (Germany); Raabe, A. [Leipzig Institute for Meteorology (LIM), Leipzig (Germany); Galas, R. [Technische Univ. Berlin (Germany). Dept. for Geodesy and Geoinformation Sciences

2013-11-01

297

Feasibility and value of fully 3D Monte Carlo reconstruction in single-photon emission computed tomography  

Science.gov (United States)

The accuracy of Single-Photon Emission Computed Tomography images is degraded by physical effects, namely photon attenuation, Compton scatter and spatially varying collimator response. The 3D nature of these effects is usually neglected by the methods used to correct for these effects. To deal with the 3D nature of the problem, a 3D projector modeling the spread of photons in 3D can be used in iterative tomographic reconstruction. The 3D projector can be estimated analytically with some approximations, or using precise Monte Carlo simulations. This latter approach has not been applied to fully 3D reconstruction yet due to impractical storage and computation time. The goal of this paper was to determine the gain to be expected from fully 3D Monte Carlo (F3DMC) modeling of the projector in iterative reconstruction, compared to conventional 2D and 3D reconstruction methods. As a proof-of-concept, two small datasets were considered. The projections of the two phantoms were simulated using the Monte Carlo simulation code GATE, as well as the corresponding projector, by taking into account all physical effects (attenuation, scatter, camera point spread function) affecting the imaging process. F3DMC was implemented by using this 3D projector in a maximum likelihood expectation maximization (MLEM) iterative reconstruction. To assess the value of F3DMC, data were reconstructed using four methods: filtered backprojection, MLEM without attenuation correction (MLEM), MLEM with attenuation correction, Jaszczak scatter correction and 3D correction for depth-dependent spatial resolution using an analytical model (MLEMC) and F3DMC. Our results suggest that F3DMC improves mainly imaging sensitivity and signal-to-noise ratio (SNR): sensitivity is multiplied by about 10 3 and SNR is increased by 20-70% compared to MLEMC. Computation of a more robust projector and application of the method on more realistic datasets are currently under investigation.

Lazaro, Delphine; Breton, Vincent; Buvat, Irène

2004-07-01

298

Towards the reconstruction of 3D orientation information from direction-sensitive X-ray projections  

Energy Technology Data Exchange (ETDEWEB)

For medical in vivo applications the resolution of a computed tomography (CT) scan is limited by the acceptable patient received dose. Thus it does not allow to image microstructures in the body. Novel X-ray contrast mechanisms provide two additional signal channels, phase contrast and dark-field contrast. In this study we report on our progress to use the dark-field signal to gain micro-structural information by reconstructing a tensor field describing the local sample scattering power. For that purpose we developed an experimental setup composed of an X-ray tube, a Talbot Lau interferometer, an Euler cradle to orient the sample and a detector. This setup allows a direct measurement of the sample scattering strength in all directions. The reconstruction of several test samples is done using filtered back-projection or the algebraic reconstruction technique. The definition of the physical model behind the reconstructed quantity is obtained from a second ansatz by using 3D density map (micro-CT) data as an input to a computer simulation of the whole setup. We consider this project important for diagnostic improvements in the case of bone pathologies. (orig.)

Malecki, Andreas; Biernath, Thomas; Bech, Martin; Potdevin, Guillaume; Pfeiffer, Franz [Technische Univ. Muenchen (Germany). Dept. of Physics (E17); Technische Univ. Muenchen (Germany). Inst. of Medical Engineering (IMETUM); Lasser, Tobias [Technische Univ. Muenchen (Germany). Chair for Computer Aided Medical Procedures and Augmented Reality (CAMP)

2011-07-01

299

3D Monte Carlo Reconstruction and Characterization of LiCoO2 Cathode  

Directory of Open Access Journals (Sweden)

Full Text Available Reconstruction and characterization of the porous composite electrode via experimental and numerical approaches are the basis and prerequisite of pore-scale modeling. The Monte Carlo approach was employed to reconstruct the LiCoO2 cathode of a Li-ion battery. The reconstructed electrode resolves sub-micrometer microstructure, thus evidently distinguishing the three individual phases: LiCoO2 as active material, pores (electrolyte, and additives. An extensive characterization was subsequently performed to calculate some important structural parameters and transport properties, including the geometrical connectivity and the specific surface area, etc. Particularly, a self-developed D3Q15 LB (Lattice Boltzmann model was used to calculate the effective thermal (or electric conductivity and the effective species diffusivity in electrolyte (or solid phase, and the tortuosity of an individual phase. The reconstructed 3D microstructure is consistent with the real cathode microstructure concerning several important statistical features including porosity, volume fraction of each phase, and two-point correlation functions etc. LB model predictions indicate that the effective transport coefficients are closely related to the micro-morphology in electrodes.

WU Wei, JIANG Fang-Ming, CHEN Zhi, WANG Ying, ZHAO Feng-Gang, ZENG Yu-Qun

2013-11-01

300

Real-time 3D computed tomographic reconstruction using commodity graphics hardware  

International Nuclear Information System (INIS)

The recent emergence of various types of flat-panel x-ray detectors and C-arm gantries now enables the construction of novel imaging platforms for a wide variety of clinical applications. Many of these applications require interactive 3D image generation, which cannot be satisfied with inexpensive PC-based solutions using the CPU. We present a solution based on commodity graphics hardware (GPUs) to provide these capabilities. While GPUs have been employed for CT reconstruction before, our approach provides significant speedups by exploiting the various built-in hardwired graphics pipeline components for the most expensive CT reconstruction task, backprojection. We show that the timings so achieved are superior to those obtained when using the GPU merely as a multi-processor, without a drop in reconstruction quality. In addition, we also show how the data flow across the graphics pipeline can be optimized, by balancing the load among the pipeline components. The result is a novel streaming CT framework that conceptualizes the reconstruction process as a steady flow of data across a computing pipeline, updating the reconstruction result immediately after the projections have been acquired. Using a single PC equipped with a single high-end commodity graphics board (the Nvidia 8800 GTX), our system is able to process clinically-sized projection data at speeds meeting and exceeding the typical flat-panel detector data production rates, enabling throughput rates of 40-50 prtes, enabling throughput rates of 40-50 projections s-1 for the reconstruction of 5123 volumes

 
 
 
 
301

3D surface reconstruction and FIB microscopy of worn alumina hip prostheses  

International Nuclear Information System (INIS)

Interest in alumina-on-alumina total hip replacements (THR) continues to grow for the young and active patient due to their superior wear performance and biocompatibility compared to the alternative traditional polymer/metal prostheses. While alumina on alumina bearings offer an excellent solution, a region of high wear, known as stripe wear, is commonly observed on retrieved alumina hip components that poses concern. These in-vivo stripe wear mechanisms can be replicated in vitro by the introduction of micro-separation during the simulated walking cycle in hip joint simulation. However, the understanding of the mechanisms behind the stripe wear processes is relatively poor. 3D topographic reconstructions of titled SEM stereo pairs from different zones have been obtained to determine the local worn surface topography. Focused ion beam (FIB) microscopy was applied to examine the subsurface damage across the stripe wear. The paper presents novel images of sub-surface microcracks in alumina along with 3D reconstructions of the worn ceramic surfaces and a classification of four distinct wear zones following microseparation in hip prostheses.

302

Moving beyond flat earth: dense 3D scene reconstruction from a single FL-LWIR camera  

Science.gov (United States)

In previous work an automatic detection system for locating buried explosive hazards in forward-looking longwave infrared (FL-LWIR) and forward-looking ground penetrating radar (FL-GPR) data was presented. This system consists of an ensemble of trainable size-contrast filters prescreener coupled with a secondary classification step which extracts cell-structured image space features, such as local binary patterns (LBP), histogram of oriented gradients (HOG), and edge histogram descriptors (EHD), from multiple looks and classifies the resulting feature vectors using a support vector machine. Previously, this system performed image space to UTM coordinate mapping under a flat earth assumption. This limited its applicability to flat terrain and short standoff distances. This paper demonstrates a technique for dense 3D scene reconstruction from a single vehicle mounted FL-LWIR camera. This technique utilizes multiple views and standard stereo vision algorithms such as polar rectification and optimal correction. Results for the detection algorithm using this 3D scene reconstruction approach on data from recent collections at an arid US Army test site are presented. These results are compared to those obtained under the flat earth assumption, with special focus on rougher terrain and longer standoff distance than in previous experiments. The most recent collection also allowed comparison between uncooled and cooled FL-LWIR cameras for buried explosive hazard detection.

Stone, K.; Keller, J. M.; Anderson, D. T.

2013-06-01

303

3D finite element model for reconstructed mixed-conducting cathodes: I. Performance quantification  

International Nuclear Information System (INIS)

The performance of a solid oxide fuel cell (SOFC) is strongly affected by electrode polarization losses, which are related to the composition and the microstructure of the porous materials. A model that can decouple the effects associated to the geometrical arrangement, shape and size of the particles together with material distribution on one side and the material properties on the other can give a relevant improvement in the understanding of the underlying processes. A porous mixed ionic–electronic conducting (MIEC) cathode was reconstructed by a tomography technique based on focused ion beam coupled with scanning electronic microscope (FIB/SEM). The detailed geometry of the microstructure is here used for 3D calculations of the electrochemical processes in the electrode. In addition, the area specific resistance (ASRcat) of the reconstructed porous cathode is calculated as a performance index. To this aim we have developed a model based on the finite element method (FEM), which numerical solution requires the use of high performance computing techniques (HPC) because of the detailed geometry. In this work we show the comparison of the 3D microstructure model with a well established 1D averaged model.

304

3D surface reconstruction and FIB microscopy of worn alumina hip prostheses  

Energy Technology Data Exchange (ETDEWEB)

Interest in alumina-on-alumina total hip replacements (THR) continues to grow for the young and active patient due to their superior wear performance and biocompatibility compared to the alternative traditional polymer/metal prostheses. While alumina on alumina bearings offer an excellent solution, a region of high wear, known as stripe wear, is commonly observed on retrieved alumina hip components that poses concern. These in-vivo stripe wear mechanisms can be replicated in vitro by the introduction of micro-separation during the simulated walking cycle in hip joint simulation. However, the understanding of the mechanisms behind the stripe wear processes is relatively poor. 3D topographic reconstructions of titled SEM stereo pairs from different zones have been obtained to determine the local worn surface topography. Focused ion beam (FIB) microscopy was applied to examine the subsurface damage across the stripe wear. The paper presents novel images of sub-surface microcracks in alumina along with 3D reconstructions of the worn ceramic surfaces and a classification of four distinct wear zones following microseparation in hip prostheses.

Zeng, P; Inkson, B J; Rainforth, W M [Department of Engineering Materials, Mappin St., University of Sheffield, Sheffield, S1 3JD (United Kingdom); Stewart, T [School of Mechanical Engineering, University of Leeds, Leeds, LS2 9JT (United Kingdom)], E-mail: m.rainforth@sheffield.ac.uk

2008-08-15

305

An Analytical Review of Stereovision Techniques to Reconstruct 3D Coordinates  

Directory of Open Access Journals (Sweden)

Full Text Available Stereovision based on 3D environment reconstruction provides a true picture of real world situations for detection of objects’ locations. This approach has specific use in the scenarios like identifying traffic jams on the roads, locating curves and bends on the roads, finding obstacles in the construction sites, etc. This paper describes different methods used in stereovision to detect images like use of trinocular stereovision, calculating correlation between left and right contours for achieving accuracy, use of prior information with intrinsic and extrinsic parameters, detection of side lane and 3D points of guardrails and fences, use of dense stereovision information, especially in urban environment. The paper also discusses Forward Collision Detection method that uses Elevation Map with Dense Stereovision, tracking of multiple objects using two-level approach and building an enhanced grid that involves obstacle cells. Hybrid dense stereo engine, which is used in urban detection scenarios is also discussed in the paper along with a solution of lane estimation in different situations using particle filtering method. Pattern matching using 3D image for pedestrian detection and lane estimation based on the particle filtering with greyscale images are also explored. The use of the rectangular digital elevation map for transforming stereo based information and the methodology used to enhance the sub pixel accuracy are also part of the paper.

Raheel Ahmed

2013-06-01

306

On the 3-D reconstruction of Coronal Mass Ejections using coronagraph data  

Directory of Open Access Journals (Sweden)

Full Text Available Coronal Mass ejections (CMEs are enormous eruptions of magnetized plasma expelled from the Sun into the interplanetary space, over the course of hours to days. They can create major disturbances in the interplanetary medium and trigger severe magnetic storms when they collide with the Earth's magnetosphere. It is important to know their real speed, propagation direction and 3-D configuration in order to accurately predict their arrival time at the Earth. Using data from the SECCHI coronagraphs onboard the STEREO mission, which was launched in October 2006, we can infer the propagation direction and the 3-D structure of such events. In this review, we first describe different techniques that were used to model the 3-D configuration of CMEs in the coronagraph field of view (up to 15 R?. Then, we apply these techniques to different CMEs observed by various coronagraphs. A comparison of results obtained from the application of different reconstruction algorithms is presented and discussed.

M. Mierla

2010-01-01

307

A System for an Accurate 3D Reconstruction in Video Endoscopy Capsule  

Directory of Open Access Journals (Sweden)

Full Text Available Since few years, the gastroenterologic examinations could have been realised by wireless video capsules. Although the images make it possible to analyse some diseases, the diagnosis could be improved by the use of the 3D Imaging techniques implemented in the video capsule. The work presented here is related to Cyclope, an embedded active vision system that is able to give in real time both 3D information and texture. The challenge is to realise this integrated sensor with constraints on size, consumption, and computational resources with inherent limitation of video capsule. In this paper, we present the hardware and software development of a wireless multispectral vision sensor which allows to transmit, a 3D reconstruction of a scene in realtime. multispectral acquisitions grab both texture and IR pattern images at least at 25 frames/s separately. The different Intellectual Properties designed allow to compute specifics algorithms in real time while keeping accuracy computation. We present experimental results with the realization of a large-scale demonstrator using an SOPC prototyping board.

Granado Bertrand

2009-01-01

308

Applying CCD Cameras in Stereo Panorama Systems for 3d Environment Reconstruction  

Science.gov (United States)

Proper recontruction of 3D environments is nowadays needed by many organizations and applications. In addition to conventional methods the use of stereo panoramas is an appropriate technique to use due to simplicity, low cost and the ability to view an environment the way it is in reality. This paper investigates the ability of applying stereo CCD cameras for 3D reconstruction and presentation of the environment and geometric measuring among that. For this purpose, a rotating stereo panorama was established using two CCDs with a base-length of 350 mm and a DVR (digital video recorder) box. The stereo system was first calibrated using a 3D test-field and used to perform accurate measurements. The results of investigating the system in a real environment showed that although this kind of cameras produce noisy images and they do not have appropriate geometric stability, but they can be easily synchronized, well controlled and reasonable accuracy (about 40 mm in objects at 12 meters distance from the camera) can be achieved.

Ashamini, A. Sh.; Varshosaz, M.; Saadatseresht, M.

2012-07-01

309

Optimal gating compared to 3D and 4D PET reconstruction for characterization of lung tumours  

Energy Technology Data Exchange (ETDEWEB)

We investigated the added value of a new respiratory amplitude-based PET reconstruction method called optimal gating (OG) with the aim of providing accurate image quantification in lung cancer. FDG-PET imaging was performed in 26 lung cancer patients during free breathing using a 24-min list-mode acquisition on a PET/CT scanner. The data were reconstructed using three methods: standard 3D PET, respiratory-correlated 4D PET using a phase-binning algorithm, and OG. These datasets were compared in terms of the maximum SUV (SUVmax) in the primary tumour (main endpoint), noise characteristics, and volumes using thresholded regions of SUV 2.5 and 40% of the SUVmax. SUVmax values from the 4D method (13.7 {+-} 5.6) and the OG method (14.1 {+-} 6.5) were higher (4.9 {+-} 4.8%, p < 0.001 and 6.9 {+-} 8.8%, p < 0.001, respectively) than that from the 3D method (13.1 {+-} 5.4). SUVmax did not differ between the 4D and OG methods (2.0 {+-} 8.4%, p = NS). Absolute and relative threshold volumes did not differ between methods, except for the 40% SUVmax volume in which the value from the 3D method was lower than that from the 4D method (-5.3 {+-} 7.1%, p = 0.007). The OG method exhibited less noise than the 4D method. Variations in volumes and SUVmax of up to 40% and 27%, respectively, of the individual gates of the 4D method were also observed. The maximum SUVs from the OG and 4D methods were comparable and significantly higher than that from the 3D method, yet the OG method was visibly less noisy than the 4D method. Based on the better quantification of the maximum and the less noisy appearance, we conclude that OG PET is a better alternative to both 3D PET, which suffers from breathing averaging, and the noisy images of a 4D PET. (orig.)

Elmpt, Wouter van; Ruysscher, Dirk de; Lambin, Philippe; Oellers, Michel [Maastricht University Medical Centre, Department of Radiation Oncology (MAASTRO), GROW - School for Oncology and Developmental Biology, Maastricht (Netherlands); Hamill, James; Jones, Judson [Siemens Medical Solutions, Knoxville, TN (United States)

2011-05-15

310

Automatic Reconstruction of 3D Building Models from Terrestrial Laser Scanner Data  

Science.gov (United States)

With modern 3D laser scanners we can acquire a large amount of 3D data in only a few minutes. This technology results in a growing number of applications ranging from the digitalization of historical artifacts to facial authentication. The modeling process demands a lot of time and work (Tim Volodine, 2007). In comparison with the other two stages, the acquisition and the registration, the degree of automation of the modeling stage is almost zero. In this paper, we propose a new surface reconstruction technique for buildings to process the data obtained by a 3D laser scanner. These data are called a point cloud which is a collection of points sampled from the surface of a 3D object. Such a point cloud can consist of millions of points. In order to work more efficiently, we worked with simplified models which contain less points and so less details than a point cloud obtained in situ. The goal of this study was to facilitate the modeling process of a building starting from 3D laser scanner data. In order to do this, we wrote two scripts for Rhinoceros 5.0 based on intelligent algorithms. The first script finds the exterior outline of a building. With a minimum of human interaction, there is a thin box drawn around the surface of a wall. This box is able to rotate 360° around an axis in a corner of the wall in search for the points of other walls. In this way we can eliminate noise points. These are unwanted or irrelevant points. If there is an angled roof, the box can also turn around the edge of the wall and the roof. With the different positions of the box we can calculate the exterior outline. The second script draws the interior outline in a surface of a building. By interior outline we mean the outline of the openings like windows or doors. This script is based on the distances between the points and vector characteristics. Two consecutive points with a relative big distance will form the outline of an opening. Once those points are found, the interior outline can be drawn. The designed scripts are able to ensure for simple point clouds: the elimination of almost all noise points and the reconstruction of a CAD model.

El Meouche, R.; Rezoug, M.; Hijazi, I.; Maes, D.

2013-11-01

311

Ultra-fast digital tomosynthesis reconstruction using general-purpose GPU programming for image-guided radiation therapy.  

Science.gov (United States)

The purpose of this work is to demonstrate an ultra-fast reconstruction technique for digital tomosynthesis (DTS) imaging based on the algorithm proposed by Feldkamp, Davis, and Kress (FDK) using standard general-purpose graphics processing unit (GPGPU) programming interface. To this end, the FDK-based DTS algorithm was programmed "in-house" with C language with utilization of 1) GPU and 2) central processing unit (CPU) cards. The GPU card consisted of 480 processing cores (2 x 240 dual chip) with 1,242 MHz processing clock speed and 1,792 MB memory space. In terms of CPU hardware, we used 2.68 GHz clock speed, 12.0 GB DDR3 RAM, on a 64-bit OS. The performance of proposed algorithm was tested on twenty-five patient cases (5 lung, 5 liver, 10 prostate, and 5 head-and-neck) scanned either with a full-fan or half-fan mode on our cone-beam computed tomography (CBCT) system. For the full-fan scans, the projections from 157.5°-202.5° (45°-scan) were used to reconstruct coronal DTS slices, whereas for the half-fan scans, the projections from both 157.5°-202.5° and 337.5°-22.5° (2 x 45°-scan) were used to reconstruct larger FOV coronal DTS slices. For this study, we chose 45°-scan angle that contained ~80 projections for the full-fan and ~160 projections with 2 x 45°-scan angle for the half-fan mode, each with 1024 x 768 pixels with 32-bit precision. Absolute pixel value differences, profiles, and contrast-to-noise ratio (CNR) calculations were performed to compare and evaluate the images reconstructed using GPU- and CPU-based implementations. The time dependence on the reconstruction volume was also tested with (512 x 512) x 16, 32, 64, 128, and 256 slices. In the end, the GPU-based implementation achieved, at most, 1.3 and 2.5 seconds to complete full reconstruction of 512 x 512 x 256 volume, for the full-fan and half-fan modes, respectively. In turn, this meant that our implementation can process > 13 projections-per-second (pps) and > 18 pps for the full-fan and half-fan modes, respectively. Since commercial CBCT system nominally acquires 11 pps (with 1 gantry-revolution-per-minute), our GPU-based implementation is sufficient to handle the incoming projections data as they are acquired and reconstruct the entire volume immediately after completing the scan. In addition, on increasing the number of slices (hence volume) to be reconstructed from 16 to 256, only minimal increases in reconstruction time were observed for the GPU-based implementation where from 0.73 to 1.27 seconds and 1.42 to 2.47 seconds increase were observed for the full-fan and half-fan modes, respectively. This resulted in speed improvement of up to 87 times compared with the CPU-based implementation (for 256 slices case), with visually identical images and small pixel-value discrepancies (processing and real-time applications that was prohibited prior due to time restrictions can now be tempered with. PMID:21728386

Park, Justin C; Park, Sung Ho; Kim, Jin Sung; Han, Youngyih; Cho, Min Kook; Kim, Ho Kyung; Liu, Zhaowei; Jiang, Steve B; Song, Bongyong; Song, William Y

2011-08-01

312

Automatic Model Selection for 3d Reconstruction of Buildings from Satellite Imagary  

Science.gov (United States)

Through the improvements of satellite sensor and matching technology, the derivation of 3D models from space borne stereo data obtained a lot of interest for various applications such as mobile navigation, urban planning, telecommunication, and tourism. The automatic reconstruction of 3D building models from space borne point cloud data is still an active research topic. The challenging problem in this field is the relatively low quality of the Digital Surface Model (DSM) generated by stereo matching of satellite data comparing to airborne LiDAR data. In order to establish an efficient method to achieve high quality models and complete automation from the mentioned DSM, in this paper a new method based on a model-driven strategy is proposed. For improving the results, refined orthorectified panchromatic images are introduced into the process as additional data. The idea of this method is based on ridge line extraction and analysing height values in direction of and perpendicular to the ridgeline direction. After applying pre-processing to the orthorectified data, some feature descriptors are extracted from the DSM, to improve the automatic ridge line detection. Applying RANSAC a line is fitted to each group of ridge points. Finally these ridge lines are refined by matching them or closing gaps. In order to select the type of roof model the heights of point in extension of the ridge line and height differences perpendicular to the ridge line are analysed. After roof model selection, building edge information is extracted from canny edge detection and parameters derived from the roof parts. Then the best model is fitted to extracted façade roofs based on detected type of model. Each roof is modelled independently and final 3D buildings are reconstructed by merging the roof models with the corresponding walls.

Partovi, T.; Arefi, H.; Krauß, T.; Reinartz, P.

2013-09-01

313

Roles of equalization in radar imaging: modeling for superesolution in 3D reconstruction  

Science.gov (United States)

In radar imaging, resolution is generally dictated by its corresponding system point spread function, the response to a point source as a result of an external excitation. This notion of resolution turns out to be rather questionable, as the interpretation of echoes received from a range of continuous targets according to a linear model allows one to cast the imaging problem as a communication system that maps the target reflectivity function onto measurements, which in turn suggests that by virtue of sampling and equalization, one can achieve unlimited spatial resolution. This article reviews the fundamental problem inherent to pulse compression in a multistatic multi-input-multi-output (MIMO) scenario, from a communications viewpoint, in both focused and un-focused scenarios. We generalize the notion of 1D range compression and replace it by a more general 4D pulse compression. The process of focusing and scanning over a 3D object can be interpreted as a MIMO 4D convolution between a reflectivity tensor and a space-varying system, which naturally induces a 4D MIMO channel convolution model. This implies that several well-established block and linear equalization methods can be easily extended to a 3D scenario with the purpose of achieving exact reconstruction of a given reflectivity volume. That is, assuming that no multiple scattering occurs, resolution is only limited in range by the sampling device in the unfocused case, while unlimited in case of focusing at multiple depths. Exact reconstruction under a zero-forcing or least-squares criterion depends solely on the amount of diversity induced by sampling in both space (via scanning rate) and time (via sampling rate), which further allows for a tradeoff between range and cross-range resolution. For instance, the fastest scanning rate is achieved by steering non overlapping beams, in which case portions of the object can be reconstructed independently from each other.

Merched, Ricardo

2012-12-01

314

A generative statistical approach to automatic 3D building roof reconstruction from laser scanning data  

Science.gov (United States)

This paper presents a generative statistical approach to automatic 3D building roof reconstruction from airborne laser scanning point clouds. In previous works, bottom-up methods, e.g., points clustering, plane detection, and contour extraction, are widely used. Due to the data artefacts caused by tree clutter, reflection from windows, water features, etc., the bottom-up reconstruction in urban areas may suffer from a number of incomplete or irregular roof parts. Manually given geometric constraints are usually needed to ensure plausible results. In this work we propose an automatic process with emphasis on top-down approaches. The input point cloud is firstly pre-segmented into subzones containing a limited number of buildings to reduce the computational complexity for large urban scenes. For the building extraction and reconstruction in the subzones we propose a pure top-down statistical scheme, in which the bottom-up efforts or additional data like building footprints are no more required. Based on a predefined primitive library we conduct a generative modeling to reconstruct roof models that fit the data. Primitives are assembled into an entire roof with given rules of combination and merging. Overlaps of primitives are allowed in the assembly. The selection of roof primitives, as well as the sampling of their parameters, is driven by a variant of Markov Chain Monte Carlo technique with specified jump mechanism. Experiments are performed on data-sets of different building types (from simple houses, high-rise buildings to combined building groups) and resolutions. The results show robustness despite the data artefacts mentioned above and plausibility in reconstruction.

Huang, Hai; Brenner, Claus; Sester, Monika

2013-05-01

315

3D-ANTLERS: Virtual Reconstruction and Three-Dimensional Measurement  

Science.gov (United States)

The main objective of this paper is to establish a procedural method for measuring and cataloguing antlers through the use of laser scanner and of a 3D reconstruction of complex modeling. The deer's antlers have been used as a test and subjected to capture and measurement. For this purpose multiple data sources techniques have been studied and compared, (also considering low-cost sensors) estimating the accuracy and its errors in order to demonstrate the validity of the process. A further development is the comparison of results with applications of digital photogrammetry, considering also cloud computing software. The study has began with an introduction to sensors, addressing the underlying characteristics of the technology available, the scope and the limits of these applications. We have focused particularly on the "structured light", as the acquisition will be completed through three-dimensional scanners: DAVID and the ARTEC MH. The first is a low-cost sensor, a basic webcam and a linear laser pointer, red coloured, that leads to acquisition of three-dimensional strips. The other one is a hand scanner; even in this case we will explain how to represent a 3D model, with a pipeline that provides data export from the "proprietary" to a "reverse engineering" software. Typically, these are the common steps to the two approaches that have been performed in WRAP format: point sampling, manual and global registration, repair normals, surface editing and texture projection. In fact, after a first and common data processing was done with the use of a software supplied with the equipment, the proto-models thus obtained were treated in Geomagic Studio, which was also chosen to allow the homogenization and standardization of data in order to make a more objective comparison. It is commonplace to observe that the editing of the digital mock-up obtained with the DAVID - which had not yet been upgraded to the 3.5 release at the time of this study - is substantially different. In the ARTEC digital mock-up for example, it shows the ability to select the individual frames, already polygonal and geo-referenced at the time of capture; however, it is not possible to make an automated texturization differently from the low-cost environment which allows to produce a good graphics' definition. Once the final 3D models were obtained, we have proceeded to do a geometric and graphic comparison of the results. Therefore, in order to provide an accuracy requirement and an assessment for the 3D reconstruction we have taken into account the following benchmarks: cost, captured points, noise (local and global), shadows and holes, operability, degree of definition, quality and accuracy. Subsequently, these studies carried out in an empirical way on the virtual reconstructions, a 3D documentation was codified with a procedural method endorsing the use of terrestrial sensors for the documentation of antlers. The results thus pursued were compared with the standards set by the current provisions (see "Manual de medición" of Government of Andalusia-Spain); to date, in fact, the identification is based on data such as length, volume, colour, texture, openness, tips, structure, etc. Data, which is currently only appreciated with traditional instruments, such as tape measure, would be well represented by a process of virtual reconstruction and cataloguing.

Barba, S.; Fiorillo, F.; De Feo, E.

2013-02-01

316

Accurate 3D reconstruction by a new PDS-OSEM algorithm for HRRT  

Science.gov (United States)

State-of-the-art high resolution research tomography (HRRT) provides high resolution PET images with full 3D human brain scanning. But, a short time frame in dynamic study causes many problems related to the low counts in the acquired data. The PDS-OSEM algorithm was proposed to reconstruct the HRRT image with a high signal-to-noise ratio that provides accurate information for dynamic data. The new algorithm was evaluated by simulated image, empirical phantoms, and real human brain data. Meanwhile, the time activity curve was adopted to validate a reconstructed performance of dynamic data between PDS-OSEM and OP-OSEM algorithms. According to simulated and empirical studies, the PDS-OSEM algorithm reconstructs images with higher quality, higher accuracy, less noise, and less average sum of square error than those of OP-OSEM. The presented algorithm is useful to provide quality images under the condition of low count rates in dynamic studies with a short scan time.

Chen, Tai-Been; Horng-Shing Lu, Henry; Kim, Hang-Keun; Son, Young-Don; Cho, Zang-Hee

2014-03-01

317

The effect of angular dose distribution on the detection of microcalcifications in digital breast tomosynthesis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Purpose: Substantial effort has been devoted to the clinical development of digital breast tomosynthesis (DBT). DBT is a three-dimensional (3D) x-ray imaging modality that reconstructs a number of thin image slices parallel to a stationary detector plane. Preliminary clinical studies have shown that the removal of overlapping breast tissue reduces image clutter and increases detectability of large, low contrast lesions. However, some studies, as well as anecdotal evidence, suggested decreased...

Hu, Yue-houng; Zhao, Wei

2011-01-01

318

Adaptive geometric tessellation for 3D reconstruction of anisotropically developing cells in multilayer tissues from sparse volumetric microscopy images.  

Science.gov (United States)

The need for quantification of cell growth patterns in a multilayer, multi-cellular tissue necessitates the development of a 3D reconstruction technique that can estimate 3D shapes and sizes of individual cells from Confocal Microscopy (CLSM) image slices. However, the current methods of 3D reconstruction using CLSM imaging require large number of image slices per cell. But, in case of Live Cell Imaging of an actively developing tissue, large depth resolution is not feasible in order to avoid damage to cells from prolonged exposure to laser radiation. In the present work, we have proposed an anisotropic Voronoi tessellation based 3D reconstruction framework for a tightly packed multilayer tissue with extreme z-sparsity (2-4 slices/cell) and wide range of cell shapes and sizes. The proposed method, named as the 'Adaptive Quadratic Voronoi Tessellation' (AQVT), is capable of handling both the sparsity problem and the non-uniformity in cell shapes by estimating the tessellation parameters for each cell from the sparse data-points on its boundaries. We have tested the proposed 3D reconstruction method on time-lapse CLSM image stacks of the Arabidopsis Shoot Apical Meristem (SAM) and have shown that the AQVT based reconstruction method can correctly estimate the 3D shapes of a large number of SAM cells. PMID:23940509

Chakraborty, Anirban; Perales, Mariano M; Reddy, G Venugopala; Roy-Chowdhury, Amit K

2013-01-01

319

Computer-aided detection of clustered microcalcifications in multiscale bilateral filtering regularized reconstructed digital breast tomosynthesis volume  

Energy Technology Data Exchange (ETDEWEB)

Purpose: Develop a computer-aided detection (CADe) system for clustered microcalcifications in digital breast tomosynthesis (DBT) volume enhanced with multiscale bilateral filtering (MSBF) regularization. Methods: With Institutional Review Board approval and written informed consent, two-view DBT of 154 breasts, of which 116 had biopsy-proven microcalcification (MC) clusters and 38 were free of MCs, was imaged with a General Electric GEN2 prototype DBT system. The DBT volumes were reconstructed with MSBF-regularized simultaneous algebraic reconstruction technique (SART) that was designed to enhance MCs and reduce background noise while preserving the quality of other tissue structures. The contrast-to-noise ratio (CNR) of MCs was further improved with enhancement-modulated calcification response (EMCR) preprocessing, which combined multiscale Hessian response to enhance MCs by shape and bandpass filtering to remove the low-frequency structured background. MC candidates were then located in the EMCR volume using iterative thresholding and segmented by adaptive region growing. Two sets of potential MC objects, cluster centroid objects and MC seed objects, were generated and the CNR of each object was calculated. The number of candidates in each set was controlled based on the breast volume. Dynamic clustering around the centroid objects grouped the MC candidates to form clusters. Adaptive criteria were designed to reduce false positive (FP) clusters based on the size, CNR values and the number of MCs in the cluster, cluster shape, and cluster based maximum intensity projection. Free-response receiver operating characteristic (FROC) and jackknife alternative FROC (JAFROC) analyses were used to assess the performance and compare with that of a previous study. Results: Unpaired two-tailedt-test showed a significant increase (p < 0.0001) in the ratio of CNRs for MCs with and without MSBF regularization compared to similar ratios for FPs. For view-based detection, a sensitivity of 85% was achieved at an FP rate of 2.16 per DBT volume. For case-based detection, a sensitivity of 85% was achieved at an FP rate of 0.85 per DBT volume. JAFROC analysis showed a significant improvement in the performance of the current CADe system compared to that of our previous system (p = 0.003). Conclusions: MBSF regularized SART reconstruction enhances MCs. The enhancement in the signals, in combination with properly designed adaptive threshold criteria, effective MC feature analysis, and false positive reduction techniques, leads to a significant improvement in the detection of clustered MCs in DBT.

Samala, Ravi K., E-mail: rsamala@umich.edu; Chan, Heang-Ping; Lu, Yao; Hadjiiski, Lubomir; Wei, Jun; Helvie, Mark A. [Department of Radiology, University of Michigan, Ann Arbor, Michigan 48109-5842 (United States); Sahiner, Berkman [Center for Devices and Radiological Health, U.S. Food and Drug Administration, Maryland 20993 (United States)

2014-02-15

320

Computer-aided detection of clustered microcalcifications in multiscale bilateral filtering regularized reconstructed digital breast tomosynthesis volume  

International Nuclear Information System (INIS)

Purpose: Develop a computer-aided detection (CADe) system for clustered microcalcifications in digital breast tomosynthesis (DBT) volume enhanced with multiscale bilateral filtering (MSBF) regularization. Methods: With Institutional Review Board approval and written informed consent, two-view DBT of 154 breasts, of which 116 had biopsy-proven microcalcification (MC) clusters and 38 were free of MCs, was imaged with a General Electric GEN2 prototype DBT system. The DBT volumes were reconstructed with MSBF-regularized simultaneous algebraic reconstruction technique (SART) that was designed to enhance MCs and reduce background noise while preserving the quality of other tissue structures. The contrast-to-noise ratio (CNR) of MCs was further improved with enhancement-modulated calcification response (EMCR) preprocessing, which combined multiscale Hessian response to enhance MCs by shape and bandpass filtering to remove the low-frequency structured background. MC candidates were then located in the EMCR volume using iterative thresholding and segmented by adaptive region growing. Two sets of potential MC objects, cluster centroid objects and MC seed objects, were generated and the CNR of each object was calculated. The number of candidates in each set was controlled based on the breast volume. Dynamic clustering around the centroid objects grouped the MC candidates to form clusters. Adaptive criteria were designed to reduce false positive (FP) clusters based on the size, CNR values and the number of MCs in the cluster, cluster shape, and cluster based maximum intensity projection. Free-response receiver operating characteristic (FROC) and jackknife alternative FROC (JAFROC) analyses were used to assess the performance and compare with that of a previous study. Results: Unpaired two-tailedt-test showed a significant increase (p < 0.0001) in the ratio of CNRs for MCs with and without MSBF regularization compared to similar ratios for FPs. For view-based detection, a sensitivity of 85% was achieved at an FP rate of 2.16 per DBT volume. For case-based detection, a sensitivity of 85% was achieved at an FP rate of 0.85 per DBT volume. JAFROC analysis showed a significant improvement in the performance of the current CADe system compared to that of our previous system (p = 0.003). Conclusions: MBSF regularized SART reconstruction enhances MCs. The enhancement in the signals, in combination with properly designed adaptive threshold criteria, effective MC feature analysis, and false positive reduction techniques, leads to a significant improvement in the detection of clustered MCs in DBT

 
 
 
 
321

Analysis of bite marks in foodstuffs by computer tomography (cone beam CT)--3D reconstruction.  

Science.gov (United States)

The use of three-dimensional (3D) analysis of forensic evidence is highlighted in comparison with traditional methods. This three-dimensional analysis is based on the registration of the surface from a bitten object. The authors propose to use Cone Beam Computed Tomography (CBCT), which is used in dental practice, in order to study the surface and interior of bitten objects and dental casts of suspects. In this study, CBCT is applied to the analysis of bite marks in foodstuffs, which may be found in a forensic case scenario. 6 different types of foodstuffs were used: chocolate, cheese, apple, chewing gum, pizza and tart (flaky pastry and custard). The food was bitten into and dental casts of the possible suspects were made. The dental casts and bitten objects were registered using an x-ray source and the CBCT equipment iCAT® (Pennsylvania, EUA). The software InVivo5® (Anatomage Inc, EUA) was used to visualize and analyze the tomographic slices and 3D reconstructions of the objects. For each material an estimate of its density was assessed by two methods: HU values and specific gravity. All the used materials were successfully reconstructed as good quality 3D images. The relative densities of the materials in study were compared. Amongst the foodstuffs, the chocolate had the highest density (median value 100.5 HU and 1,36 g/cm(3)), while the pizza showed to have the lowest (median value -775 HU and 0,39 g/cm(3)), on both scales. Through tomographic slices and three-dimensional reconstructions it was possible to perform the metric analysis of the bite marks in all the foodstuffs, except for the pizza. These measurements could also be obtained from the dental casts. The depth of the bite mark was also successfully determined in all the foodstuffs except for the pizza. Cone Beam Computed Tomography has the potential to become an important tool for forensic sciences, namely for the registration and analysis of bite marks in foodstuffs that may be found in a crime scene. PMID:24776435

Marques, Jeidson; Musse, Jamilly; Caetano, Catarina; Corte-Real, Francisco; Corte-Real, Ana Teresa

2013-12-01

322

Modeling, measurement, and 3-D equilibrium reconstruction of the bootstrap current in the Helically Symmetric Experiment  

Science.gov (United States)

The bootstrap current for three electron cyclotron resonance heated plasma scenarios in a quasihelically symmetric stellarator (the Helically Symmetric Experiment) are analyzed and compared to a neoclassical transport code PENTA. The three conditions correspond to 50 kW input power with a resonance that is off-axis, 50 kW on-axis heating and 100 kW on-axis heating. When the heating location was moved from off-axis to on-axis with 50 kW heating power, the stored energy and the extrapolated steady-state current were both observed to increase. When the on-axis heating power was increased from 50 kW to 100 kW, the stored energy continued to increase while the bootstrap current slightly decreased. This trend is qualitatively in agreement with the calculations which indicate that a large positive electric field for the 100 kW case was driving the current negative in a small region close to the magnetic axis and accounting for the decrease in the total integrated current. This trend in the calculations is only observed to occur when momentum conservation between particle species is included. Without momentum conservation, the calculated bootstrap current increases monotonically. We show that the magnitude of the bootstrap current as calculated by PENTA agrees better with the experiment when momentum conservation between plasma species is included in the calculation. The total current was observed in all cases to flow in a direction to unwind the transform, unlike in a tokamak in which the bootstrap current adds to the transform. The 3-D inductive response of the plasma is simulated to predict the evolution of the current profile during the discharge. The 3-D equilibrium reconstruction code V3FIT is used to reconstruct profiles of the plasma pressure and current constrained by measurements with a set of magnetic diagnostics. The reconstructed profiles are consistent with the measured plasma pressure profile and the simulated current profile when the reconstruction is constrained by the measured data from a diagnostic array that is internal to the vacuum chamber.

Schmitt, J. C.; Talmadge, J. N.; Anderson, D. T.; Hanson, J. D.

2014-09-01

323

3D Reconstruction Using Interval Methods on The Kinect Device Coupled With an IMU  

Directory of Open Access Journals (Sweden)

Full Text Available The principle behind VSLAM applications like 3D object reconstruction or indoor mapping is to estimate the spatial transformation between two large clouds of points, which represent two poses of the same scene. They can further be processed to obtain detailed surfaces. Since its introduction in 1992, the standard algorithm for finding the alignment between two point clouds is ICP (Iterative Closest Point and its variants, combined with RANSAC (RANdom SAmple Consensus. This paper presents a new approach using interval analysis. The idea is to define large intervals for the transformation parameters between the poses then to successively contract those intervals using the equations of the transformation of corresponding points between the poses. To contract those intervals faster, we added an IMU (Inertial Measurement Unit to our system so the initial intervals of the parameters are already small before applying the contractions. We implemented our algorithm using the middleware ROS (Robot Operating System and stated our performances.

Aymeric Bethencourt

2013-02-01

324

3D finite element model for reconstructed mixed-conducting cathodes: II. Parameter sensitivity analysis  

International Nuclear Information System (INIS)

A micro-model for the calculation of the area specific resistance ASRcat of a porous mixed ionic electronic conducting (MIEC) cathode, which resolves the microstructure, has been presented in Part I of this article. Four processes are considered relevant for a parametric study of this solid oxide fuel cell (SOFC) model. These comprise a charge transfer process between the electrode and the electrolyte and three noncharge transfer processes in the porous electrode: (i) gas diffusion, (ii) bulk diffusion and (iii) surface reaction. In Part II we present a systematic parameter sensitivity analysis of the four parameters that describe these processes. We define an index called sensitivity factor that allows the quantitative determination of the importance of the different processes for a reconstructed 3D microstructure.

325

Morphology and function of Bast's valve: additional insight in its functioning using 3D-reconstruction.  

Science.gov (United States)

The utriculo-endolymphatic valve was discovered by Bast in 1928. The function of Bast's valve is still unclear. By means of orthogonal-plane fluorescence optical sectioning (OPFOS) microscopy 3D-reconstructions of the valve and its surrounding region are depicted. The shape of the duct at the utricular side is that of a flattened funnel. In the direction of the endolymphatic duct and sac this funnel runs into a very narrow duct. The valve itself has a rigid 'arch-like' configuration. The opposing thin, one cell-layer thick, utricular membrane is highly compliant. We propose that opening and closure of the valve occurs through movement of the flexible base/utricular membrane away from and toward the relatively rigid valve lip. PMID:17724606

Hofman, R; Segenhout, J M; Buytaert, J A N; Dirckx, J J J; Wit, H P

2008-02-01

326

Enhancing tissue structures with iterative image reconstruction for digital breast tomosynthesis  

Science.gov (United States)

We design an iterative image reconstruction (IIR) algorithm for enhancing tissue structure contrast. The algorithm takes advantage of a data fidelity term, which compares the derivative of the DBT projections with the derivative of the estimated projections. This derivative data fidelity is sensitive to the edges of tissue structure projections, and as a consequence minimizing the corresponding the data-error term brings out structure information in the reconstructed volumes. The method has the practical advantages that few iterations are required and that direct region-of-interest (ROI) reconstruction is possible with the proposed derivative data fidelity term. Both of these advantages reduce the computational burden of the IIR algorithm and potentially make it feasible for clinical application. The algorithm is demonstrated on clinical DBT data.

Sidky, Emil Y.; Reiser, Ingrid S.; Nishikawa, Robert M.; Pan, Xiaochuan

2014-03-01

327

Integration of knowledge to support automatic object reconstruction from images and 3D data  

International Nuclear Information System (INIS)

Object reconstruction is a important task in many fields of application as it allows to generate digital representations of our physical world used as base for analysis, planning, construction, visualization or other aims. A reconstruction itself normally is based on reliable data (images, 3D point clouds for example) expressing the object in his complete extension. This data then has to be compiled and analyzed in order to extract all necessary geometrical elements, which represent the object and form a digital copy of it. Traditional strategies are largely based on manual interaction and interpretation, because with increasing complexity of objects human understanding is inevitable to achieve acceptable and reliable results. But human interaction is time consuming and expensive, why many research has already been invested to integrate algorithmic support, what allows to speed up the process and reduce manual work load. Presently most such algorithms are data-driven and concentrate on specific features of the objects, being accessible to numerical models. By means of these models, which normally will represent geometrical (flatness, roughness, for example) or physical features (color, texture), the data is classified and analyzed. This is succesful for objects with a limited complexity, but gets to its limits with increasing complexity of objects. Then purely numerical strategies are not able to sufficiently model the reality. Therefore, the intention of our approach is to take human cogni-tive strategy as an example, and to simulate extraction processes based on available knowledge for the objects of interest. Such processes will introduce a semantic structure for the objects and guide the algorithms used to detect and recognize objects, which will yield a higher effectiveness. Hence, our research proposes an approach using knowledge to guide the algorithms in 3D point cloud and image processing.

328

An analytic model of pinhole aperture penetration for 3D pinhole SPECT image reconstruction  

International Nuclear Information System (INIS)

Photons penetrate the attenuating material close to the aperture of pinhole collimators in nuclear medicine, broadening the tails of point spread functions (PSFs) and degrading the resolution of planar and SPECT images. An analytic approximation has been developed that models this penetration contribution to the PSF for knife-edge point pinhole apertures. The approximation has the form exp(-?r), where r is the distance on the detector surface from the projection of the point source through the pinhole. The rolloff coefficient ? is a function of the photon energy, point source location and the design parameters of the collimator. There was excellent agreement between measured values of ? from photon transport simulations of I-131 point sources (364 keV emission only) and theoretical predictions from the analytic formula. Predicted ? values from the analytic formula averaged 25% greater than measured values from experimental I-131 point source acquisitions. Photon transport simulations were performed that modelled the 364 keV and less abundant 637 and 723 keV emissions and scatter within the scintillation crystal. Measured ? values from these simulations averaged 12% greater than the experimental values, indicating that about half of the error between the analytic formula and the experimental measurements was due to unmodelled 637 and 723 keV emissions. The remaining error may be due in part to scatter in the pinhole region and backscatter from gamma camera components behind the scintillation crystal. The analytic penetration model was used in designing Metz filters to compensate for penetration blur and these filters were applied to the projection data as part of 3D SPECT image reconstruction. Image resolution and contrast were improved in simulated and experimental I-131 tumour phantom studies. This analytic model of pinhole aperture penetration can be readily incorporated into iterative 3D SPECT pinhole reconstruction algorithms. (author)

329

3D reconstruction of prostate histology based on quantified tissue cutting and deformation parameters  

Science.gov (United States)

Methods for 3D histology reconstruction from sparse 2D digital histology images depend on knowledge about the positions, orientations, and deformations of tissue slices due to the histology process. This work quantitatively evaluates typical assumptions about the position and orientation of whole-mount prostate histology sections within coarsely sliced tissue blocks and about the deformation of tissue during histological processing and sectioning. 3-5 midgland tissue blocks from each of 7 radical prostatectomy specimens were imaged using magnetic resonance imaging before histology processing. After standard whole-mount paraffin processing and sectioning, the resulting sections were digitised. Homologous anatomic landmarks were identified on 22 midgland histology and MR images. Orientations and depths of sections relative to the front faces of the tissue blocks were measured based on the best-fit plane through the landmarks on the MR images. The mean+/-std section orientation was 1.7+/-1.1° and the mean+/-std depth of the sections was 1.0+/-0.5 mm. Deformation was assessed by using four transformation models (rigid, rigid+scale, affine and thin-plate-spline (TPS)) to align landmarks from histology and MR images, and evaluating each by measuring the target registration error (TRE) using a leave-one-out cross-validation. The rigid transformation model had higher mean TRE (p<0.001) than the other models, and the rigid+scale and affine models had higher mean TRE than the TPS model (p<0.001 and p<0.01 respectively). These results informed the design and development of a method for 3D prostate histology reconstruction based on extrinsic strand-shaped fiducial markers which yielded a 0.7+/-0.4 mm mean+/-std TRE.

Gibson, Eli; Gómez, José A.; Moussa, Madeleine; Crukley, Cathie; Bauman, Glenn; Fenster, Aaron; Ward, Aaron D.

2012-03-01

330

Zooming in: high resolution 3D reconstruction of differently stained histological whole slide images  

Science.gov (United States)

Much insight into metabolic interactions, tissue growth, and tissue organization can be gained by analyzing differently stained histological serial sections. One opportunity unavailable to classic histology is three-dimensional (3D) examination and computer aided analysis of tissue samples. In this case, registration is needed to reestablish spatial correspondence between adjacent slides that is lost during the sectioning process. Furthermore, the sectioning introduces various distortions like cuts, folding, tearing, and local deformations to the tissue, which need to be corrected in order to exploit the additional information arising from the analysis of neighboring slide images. In this paper we present a novel image registration based method for reconstructing a 3D tissue block implementing a zooming strategy around a user-defined point of interest. We efficiently align consecutive slides at increasingly fine resolution up to cell level. We use a two-step approach, where after a macroscopic, coarse alignment of the slides as preprocessing, a nonlinear, elastic registration is performed to correct local, non-uniform deformations. Being driven by the optimization of the normalized gradient field (NGF) distance measure, our method is suitable for differently stained and thus multi-modal slides. We applied our method to ultra thin serial sections (2 ?m) of a human lung tumor. In total 170 slides, stained alternately with four different stains, have been registered. Thorough visual inspection of virtual cuts through the reconstructed block perpendicular to the cutting plane shows accurate alignment of vessels and other tissue structures. This observation is confirmed by a quantitative analysis. Using nonlinear image registration, our method is able to correct locally varying deformations in tissue structures and exceeds the limitations of globally linear transformations.

Lotz, Johannes; Berger, Judith; Müller, Benedikt; Breuhahn, Kai; Grabe, Niels; Heldmann, Stefan; Homeyer, André; Lahrmann, Bernd; Laue, Hendrik; Olesch, Janine; Schwier, Michael; Sedlaczek, Oliver; Warth, Arne

2014-03-01

331

An analytic model of pinhole aperture penetration for 3D pinhole SPECT image reconstruction  

Energy Technology Data Exchange (ETDEWEB)

Photons penetrate the attenuating material close to the aperture of pinhole collimators in nuclear medicine, broadening the tails of point spread functions (PSFs) and degrading the resolution of planar and SPECT images. An analytic approximation has been developed that models this penetration contribution to the PSF for knife-edge point pinhole apertures. The approximation has the form exp(-{gamma}r), where r is the distance on the detector surface from the projection of the point source through the pinhole. The rolloff coefficient {gamma} is a function of the photon energy, point source location and the design parameters of the collimator. There was excellent agreement between measured values of {gamma} from photon transport simulations of I-131 point sources (364 keV emission only) and theoretical predictions from the analytic formula. Predicted {gamma} values from the analytic formula averaged 25% greater than measured values from experimental I-131 point source acquisitions. Photon transport simulations were performed that modelled the 364 keV and less abundant 637 and 723 keV emissions and scatter within the scintillation crystal. Measured {gamma} values from these simulations averaged 12% greater than the experimental values, indicating that about half of the error between the analytic formula and the experimental measurements was due to unmodelled 637 and 723 keV emissions. The remaining error may be due in part to scatter in the pinhole region and backscatter from gamma camera components behind the scintillation crystal. The analytic penetration model was used in designing Metz filters to compensate for penetration blur and these filters were applied to the projection data as part of 3D SPECT image reconstruction. Image resolution and contrast were improved in simulated and experimental I-131 tumour phantom studies. This analytic model of pinhole aperture penetration can be readily incorporated into iterative 3D SPECT pinhole reconstruction algorithms. (author)

Smith, Mark F.; Jaszczak, Ronald J. [Department of Radiology, Duke University Medical Center, Durham, NC (United States); Department of Biomedical Engineering, Duke University, Durham, NC (United States)

1998-04-01

332

3D Reconstruction of the Vortex in a Human Right Ventricle Model using High Speed PIV  

Science.gov (United States)

This work aims to characterize the formation process and translation of the vortex, which forms along with the trans-tricuspid jet in a realistic model of a human right ventricle (RV). A clear model of the RV made of silicone rubber was carefully casted in real size from echocardiographic data of an adult human heart. The RV model was used in our heart pulsed-flow simulator at KLAB at UCI to perform experiments. Bioprosthetic heart valves in appropriate sizes were used at tricuspid and pulmonary positions. Multi-planar high-speed PIV was performed to capture and reconstruct the 3D flow field with a 1-millisecond time gap between each two velocity frames. ?2 iso-surfaces were used to illustrate the evolution of vortex cores. The highly asymmetric shape of the RV chamber results in a complex 3D trans-tricuspid vortex that forms and translates toward right ventricular outflow tract, and finally departs RV from pulmonary valve. Through this study, -for the first time- the formation, evolution and pathway of the RV vortex have been characterized in vitro.

Kheradvar, Arash; Falahatpisheh, Ahmad

2011-11-01

333

4D reconstruction of the past: the image retrieval and 3D model construction pipeline  

Science.gov (United States)

One of the main characteristics of the Internet era we are living in, is the free and online availability of a huge amount of data. This data is of varied reliability and accuracy and exists in various forms and formats. Often, it is cross-referenced and linked to other data, forming a nexus of text, images, animation and audio enabled by hypertext and, recently, by the Web3.0 standard. Our main goal is to enable historians, architects, archaeolo- gists, urban planners and affiliated professionals to reconstruct views of historical monuments from thousands of images floating around the web. This paper aims to provide an update of our progress in designing and imple- menting a pipeline for searching, filtering and retrieving photographs from Open Access Image Repositories and social media sites and using these images to build accurate 3D models of archaeological monuments as well as enriching multimedia of cultural / archaeological interest with metadata and harvesting the end products to EU- ROPEANA. We provide details of how our implemented software searches and retrieves images of archaeological sites from Flickr and Picasa repositories as well as strategies on how to filter the results, on two levels; a) based on their built-in metadata including geo-location information and b) based on image processing and clustering techniques. We also describe our implementation of a Structure from Motion pipeline designed for producing 3D models using the large collection of 2D input images (>1000) retrieved from Internet Repositories.

Hadjiprocopis, Andreas; Ioannides, Marinos; Wenzel, Konrad; Rothermel, Mathias; Johnsons, Paul S.; Fritsch, Dieter; Doulamis, Anastasios; Protopapadakis, Eftychios; Kyriakaki, Georgia; Makantasis, Kostas; Weinlinger, Guenther; Klein, Michael; Fellner, Dieter; Stork, Andre; Santos, Pedro

2014-08-01

334

Customized Foot Orthosis Development by 3D Reconstruction of the CT Images  

Directory of Open Access Journals (Sweden)

Full Text Available Clinicians can provide a means to better distribute the pressure around the foot, and can also correct the biomechanics of the foot by using a customized shoe insole. If detected early enough, orthopedic insoles can correct or prevent further complications. In this study the 3 Dimensional (D model of the foot was used to fabricate a customized orthosis. The Computed Tomography (CT images of patient’s foot having no muscle weakness and joint restriction were acquired. The gray intensities corresponding to the bones of the foot from the CT images were 3 dimensionally reconstructed. The 3D model of the foot was then imported into the CAD Software. Boolean operations were carried out in between the 3D foot model and a solid rectangular surface to create a customized foot orthosis. The exact contours and shape of the subject’s foot was acquired using the computerized method of fabricating an orthosis. The novel idea described in this study support, automating the process of designing a customized orthosis with the impression got from the 3 dimensionally modeled feet, thereby reducing the modeling time considerably. The simple technique used in this process will help in giving comfort and stability to the patient’s feet while walking.

Sathish Kumar Paul

2012-10-01

335

Reduced memory augmented Lagrangian algorithm for 3D iterative x-ray CT image reconstruction  

Science.gov (United States)

Although statistical image reconstruction methods for X-ray CT can provide improved image quality at reduced patient doses, computation times for 3D axial and helical CT are a challenge. Rapidly converging algorithms are needed for practical use. Augmented Lagrangian methods based on variable splitting recently have been found to be effective for image denoising and deblurring applications.5 These methods are particularly effective for non-smooth regularizers such as total variation or those involving the 1 norm. However, when standard "split Bregman" methods6 are applied directly to 3D X-ray CT problems, numerous auxiliary variables are needed, leading to undesirably high memory requirements.7 For minimizing regularized, weighted least-squares (WLS) cost functions, we propose a new splitting approach for CT, based on the alternating direction method of multipliers (ADMM)1,5 that has multiple benefits over previous methods: (i) reduced memory requirements, (ii) effective preconditioning using modified ramp/cone filters, (iii) accommodating very general regularizers including edge-preserving roughness penalties, total variation methods, and sparsifying transforms like wavelets. Numerical results show that the proposed algorithm converges rapidly, and that the cone filter is particularly effective for accelerating convergence.

McGaffin, Madison G.; Ramani, Sathish; Fessler, Jeffrey A.

2012-03-01

336

Optimal relaxation parameters of DRAMA (dynamic RAMLA) aiming at one-pass image reconstruction for 3D-PET  

International Nuclear Information System (INIS)

We have reported a block-iterative algorithm named DRAMA for image reconstruction for emission tomography (Tanaka and Kudo 2003 Phys. Med. Biol. 48 1405-22). DRAMA is a modified version of the row-action maximum likelihood algorithm (RAMLA), in which the relaxation parameter is subset dependent and is changed in such a way that the noise propagation from subsets to the reconstructed image is substantially independent of the access order of the subsets. The algorithm provides fast convergence with a reasonable signal-to-noise ratio. The optimal relaxation parameter has been derived assuming a two-dimensional (2D)-PET model, and detailed performance in three-dimensional (3D) reconstruction has not been clear enough. We have developed the new version 'DRAMA-3D', based on the 3D-PET model. The optimal relaxation parameter is a function of the access order of the subsets and the ring difference, and its value is determined by simple formulas from the design parameters of the PET scanner, the operating conditions and the post-smoothing resolution. In this paper, we present the theory of DRAMA-3D, the results of simulation studies on the performance of DRAMA-3D and the comparative studies of the related algorithms. It is shown that DRAMA-3D is robust for various access orders of subsets and is suitable to realize one-pass (single-iteration) reconstruction.

337

Optimal relaxation parameters of DRAMA (dynamic RAMLA) aiming at one-pass image reconstruction for 3D-PET  

Energy Technology Data Exchange (ETDEWEB)

We have reported a block-iterative algorithm named DRAMA for image reconstruction for emission tomography (Tanaka and Kudo 2003 Phys. Med. Biol. 48 1405-22). DRAMA is a modified version of the row-action maximum likelihood algorithm (RAMLA), in which the relaxation parameter is subset dependent and is changed in such a way that the noise propagation from subsets to the reconstructed image is substantially independent of the access order of the subsets. The algorithm provides fast convergence with a reasonable signal-to-noise ratio. The optimal relaxation parameter has been derived assuming a two-dimensional (2D)-PET model, and detailed performance in three-dimensional (3D) reconstruction has not been clear enough. We have developed the new version 'DRAMA-3D', based on the 3D-PET model. The optimal relaxation parameter is a function of the access order of the subsets and the ring difference, and its value is determined by simple formulas from the design parameters of the PET scanner, the operating conditions and the post-smoothing resolution. In this paper, we present the theory of DRAMA-3D, the results of simulation studies on the performance of DRAMA-3D and the comparative studies of the related algorithms. It is shown that DRAMA-3D is robust for various access orders of subsets and is suitable to realize one-pass (single-iteration) reconstruction.

Tanaka, Eiichi [Hamamatsu Photonics KK, Tokyo Branch, Mori-Bldg No 33, Toranomon, Minato-ku, Tokyo (Japan); Kudo, Hiroyuki [Department of Computer Science, Graduate School of Systems and Information Engineering, University of Tsukuba, Tsukuba-shi, Ibaraki (Japan)

2010-05-21

338

A LabVIEW based user-friendly nano-CT image alignment and 3D reconstruction platform  

CERN Document Server

X-ray nanometer computed tomography (nano-CT) offers applications and opportunities in many scientific researches and industrial areas. Here we present a user-friendly and fast LabVIEW based package running, after acquisition of the raw projection images, a procedure to obtain the inner structure of the sample under analysis. At first, a reliable image alignment procedure fixes possible misalignments among image series due to mechanical errors, thermal expansion and other external contributions, then a novel fast parallel beam 3D reconstruction performs the tomographic reconstruction. The remarkable improved reconstruction after the image calibration confirms the fundamental role of the image alignment procedure. It minimizes blurring and additional streaking artifacts present in a reconstructed slice that cause loss of information and faked structures in the observed material. The nano-CT image alignment and 3D reconstruction LabVIEW package significantly reducing the data process, makes faster and easier th...

Wang, Shenghao; Wang, Zhili; Gao, Kun; Wu, Zhao; Zhu, Peiping; Wu, Ziyu

2014-01-01

339

3D reconstruction and manufacture of real abdominal aortic aneurysms: from CT scan to silicone model.  

Science.gov (United States)

Abdominal aortic aneurysm (AAA) can be defined as a permanent and irreversible dilation of the infrarenal aorta. AAAs are often considered to be an aorta with a diameter 1.5 times the normal infrarenal aorta diameter. This paper describes a technique to manufacture realistic silicone AAA models for use with experimental studies. This paper is concerned with the reconstruction and manufacturing process of patient-specific AAAs. 3D reconstruction from computed tomography scan data allows the AAA to be created. Mould sets are then designed for these AAA models utilizing computer aided designcomputer aided manufacture techniques and combined with the injection-moulding method. Silicone rubber forms the basis of the resulting AAA model. Assessment of wall thickness and overall percentage difference from the final silicone model to that of the computer-generated model was performed. In these realistic AAA models, wall thickness was found to vary by an average of 9.21%. The percentage difference in wall thickness recorded can be attributed to the contraction of the casting wax and the expansion of the silicone during model manufacture. This method may be used in conjunction with wall stress studies using the photoelastic method or in fluid dynamic studies using a laser-Doppler anemometry. In conclusion, these patient-specific rubber AAA models can be used in experimental investigations, but should be assessed for wall thickness variability once manufactured. PMID:18532870

Doyle, B J; Morris, L G; Callanan, A; Kelly, P; Vorp, D A; McGloughlin, T M

2008-06-01

340

Cardiac C-arm computed tomography using a 3D + time ROI reconstruction method with spatial and temporal regularization  

Energy Technology Data Exchange (ETDEWEB)

Purpose: Reconstruction of the beating heart in 3D + time in the catheter laboratory using only the available C-arm system would improve diagnosis, guidance, device sizing, and outcome control for intracardiac interventions, e.g., electrophysiology, valvular disease treatment, structural or congenital heart disease. To obtain such a reconstruction, the patient's electrocardiogram (ECG) must be recorded during the acquisition and used in the reconstruction. In this paper, the authors present a 4D reconstruction method aiming to reconstruct the heart from a single sweep 10 s acquisition. Methods: The authors introduce the 4D RecOnstructiOn using Spatial and TEmporal Regularization (short 4D ROOSTER) method, which reconstructs all cardiac phases at once, as a 3D + time volume. The algorithm alternates between a reconstruction step based on conjugate gradient and four regularization steps: enforcing positivity, averaging along time outside a motion mask that contains the heart and vessels, 3D spatial total variation minimization, and 1D temporal total variation minimization. Results: 4D ROOSTER recovers the different temporal representations of a moving Shepp and Logan phantom, and outperforms both ECG-gated simultaneous algebraic reconstruction technique and prior image constrained compressed sensing on a clinical case. It generates 3D + time reconstructions with sharp edges which can be used, for example, to estimate the patient's left ventricular ejection fraction. Conclusions: 4D ROOSTER can be applied for human cardiac C-arm CT, and potentially in other dynamic tomography areas. It can easily be adapted to other problems as regularization is decoupled from projection and back projection.

Mory, Cyril, E-mail: cyril.mory@philips.com [Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, F-69621 Villeurbanne Cedex (France); Philips Research Medisys, 33 rue de Verdun, 92156 Suresnes (France); Auvray, Vincent; Zhang, Bo [Philips Research Medisys, 33 rue de Verdun, 92156 Suresnes (France); Grass, Michael; Schäfer, Dirk [Philips Research, Röntgenstrasse 24–26, D-22335 Hamburg (Germany); Chen, S. James; Carroll, John D. [Department of Medicine, Division of Cardiology, University of Colorado Denver, 12605 East 16th Avenue, Aurora, Colorado 80045 (United States); Rit, Simon [Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1 (France); Centre Léon Bérard, 28 rue Laënnec, F-69373 Lyon (France); Peyrin, Françoise [Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, F-69621 Villeurbanne Cedex (France); X-ray Imaging Group, European Synchrotron, Radiation Facility, BP 220, F-38043 Grenoble Cedex (France); Douek, Philippe; Boussel, Loïc [Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1 (France); Hospices Civils de Lyon, 28 Avenue du Doyen Jean Lépine, 69500 Bron (France)

2014-02-15

 
 
 
 
341

Orientation determination by wavelets matching for 3D reconstruction of very noisy electron microscopic virus images  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background In order to perform a 3D reconstruction of electron microscopic images of viruses, it is necessary to determine the orientation (Euler angels of the 2D projections of the virus. The projections containing high resolution information are usually very noisy. This paper proposes a new method, based on weighted-projection matching in wavelet space for virus orientation determination. In order to speed the retrieval of the best match between projections from a model and real virus particle, a hierarchical correlation matching method is also proposed. Results A data set of 600 HSV-1 capsid particle images in different orientations was used to test the proposed method. An initial model of about 40 Å resolutions was used to generate projections of an HSV-1 capsid. Results show that a significant improvement, in terms of accuracy and speed, is obtained for the initial orientation estimates of noisy herpes virus images. For the bacteriophage (P22, the proposed method gave the correct reconstruction compared to the model, while the classical method failed to resolve the correct orientations of the smooth spherical P22 viruses. Conclusion This paper introduces a new method for orientation determination of low contrast images and highly noisy virus particles. This method is based on weighted projection matching in wavelet space, which increases the accuracy of the orientations. A hierarchical implementation of this method increases the speed of orientation determination. The estimated number of particles needed for a higher resolution reconstruction increased exponentially. For a 6 Å resolution reconstruction of the HSV virus, 50,000 particles are necessary. The results show that the proposed method reduces the amount of data needed in a reconstruction by at least 50 %. This may result in savings 2 to 3 man-years invested in acquiring images from the microscope and data processing. Furthermore, the proposed method is able to determine orientations for some difficult particles like P22 with accuracy and consistency. Recently a low PH sindbis capsid was determined with the proposed method, where other methods based on the common line fail.

Saad Ali

2005-03-01

342

Computer-aided interactive surgical simulation for craniofacial anomalies based on 3-D surface reconstruction CT images  

International Nuclear Information System (INIS)

We developed a computer-aided interactive surgical simulation system for craniofacial anomalies based on three-dimensional (3-D) surface reconstruction CT imaging. This system has four functions: 1) 3-D surface reconstruction display with an accelerated projection method; 2) Surgical simulation to cut, move, rotate, and reverse bone-blocks over the reference 3-D image on the CRT screen; 3) 3-D display of the simulated image in arbitrary views; and 4) Prediction of postoperative skin surface features displayed as 3-D images in arbitrary views. Retrospective surgical simulation has been performed on three patients who underwent the fronto-orbital advancement procedures for brachycephaly and two who underwent the reconstructive procedure for scaphocephaly. The predicted configurations of the cranium and skin surface were well simulated when compared to the postoperative images in 3-D arbitrary views. In practical use, this software might be used for an on-line system connected to a large scale general-purpose computer. (author)

343

Mesure de netteté basée sur les descripteurs généralisés de Fourier appliquée à la reconstruction 3D par Shape from Focus  

Digital Repository Infrastructure Vision for European Research (DRIVER)

L'étape principale de la méthode de reconstruction 3D " Shape from Focus " est l'utilisation d'un opérateur de mesure de netteté de chaque pixel de la séquence d'image. Le choix de l'opérateur de mesure de netteté est une étape cruciale pour une reconstruction 3D de qualité. La précision de la mesure de netteté dépend de la taille du voisinage autour du pixel choisi et de la présence ou non de bruit additif dans la séquence d'images. Dans cet article, nous présentons deux nouve...

Billiot, Bastien; Cointault, Fre?de?ric; Gouton, Pierre

2013-01-01

344

Examination of a novel reconstruction function in 3D CT angiography  

International Nuclear Information System (INIS)

A novel reconstruction function, VR Kernel (VRK), was evaluated by comparison with the conventional standard function (Standard) for imaging of blood vessels and their morphology by 3D-CT angiography (3D-CTA) of abdomen. The machine was PHILIPS Brilliance CT64 with the workstation of Extended Brilliance Work Space and AZE Virtual Place Lexus, PHILIPS EBW AVA software was for measuring the blood vessel diameter, and image analytical software was that of Kanazawa Univ. for calculating modulation transfer function (MTF). Examinations were on the resolution and noise characteristics with use of PHILIPS head and trunk phantom, on shape appearance and diameters with Kyoto-Kagaku simulated blood vessel phantom and on visual observation of the actual clinical 3D-CTA image at the level of renal artery of human abdomen for seeing the surface shape and calcification on aorta and the capacity of image characterization of peripheral vessels. VRK was found to give higher MTF values at up to 0.4 cycles/mm than Standard, indicating satisfactory spatial resolution and as well, larger standard deviation (SD) values suggestive of lower image quality. However, in the examination of shape appearance, VRK image quality was comparable to Standard's and capacity was improved at 1.8-1.0 mm diameter, probably by the increased CT number of the vessels. Further, steeper peak was given in the profiling curve of the simulated vessel by VRK, suggesting its clearer imaging. At the normal level (imagclearer imaging. At the normal level (image at CT number of aorta, ca. 350 HU and SD, ca. 10), the clinical image quality was seemingly improved in VRK, and the capacity to characterize peripheral vessels was better despite roughness of the whole image at the poor level (CT number, at 200 and SD, ca. 15). VRK was thus found to more clearly display the margin of blood vessels due to the improved image quality by increased CT number, and to give better shape appearance, and was thought to be more useful to observe the peripheral vessels. (T.T.)

345

ESTIMATION OF TORTUOSITY AND RECONSTRUCTION OF GEODESIC PATHS IN 3D  

Directory of Open Access Journals (Sweden)

Full Text Available The morphological tortuosity of a geodesic path in a medium can be defined as the ratio between its geodesic length and the Euclidean distance between its two extremities. Thus, the minimum tortuosity of all the geodesic paths into a medium in 2D or in 3D can be estimated by image processing methodsusing mathematical morphology. Considering a medium, the morphological tortuosities of its internal paths are estimated according to one direction, which is perpendicular to both starting and ending opposite extremities of the geodesicpaths. The used algorithm estimates the morphological tortuosities from geodesic distance maps, which are obtained from geodesic propagations. The shape of the propagated structuring element used to estimate the geodesic distance maps on a discrete grid has a direct influence on the morphological tortuosity and has to be chosen very carefully. The results of our algorithm is an image with pixels p having a value equal to the length of the shortest path containing p and connected to two considered opposite boundaries A and B of the image. The analysis of the histogram of the morphological tortuosities gives access to their statistical distribution. Moreover, for each tortuosity the paths can be extracted from the original image, which highlights the location of them into the sample. However, these geodesic paths have to be reconstructed for further processing. The extraction, because applying a threshold on the tortuosities, results in disconnected components, especially for highly tortuous paths. This reconstruction consists in reconnecting these components to the geodesic path linking the two opposite faces, by means of a backtracking algorithm.

Charles Peyrega

2013-03-01

346

First report of fossil "keratose" demosponges in Phanerozoic carbonates: preservation and 3-D reconstruction  

Science.gov (United States)

Fossil record of Phanerozoic non-spicular sponges, beside of being important with respect to the lineage evolution per se, could provide valuable references for the investigation of Precambrian ancestral animal fossils. However, although modern phylogenomic studies resolve non-spicular demosponges as the sister group of the remaining spiculate demosponges, the fossil record of the former is extremely sparse or unexplored compared to that of the latter; the Middle Cambrian Vauxiidae Walcott 1920, is the only confirmed fossil taxon of non-spicular demosponges. Here, we describe carbonate materials from Devonian (Upper Givetian to Lower Frasnian) bioherms of northern France and Triassic (Anisian) microbialites of Poland that most likely represent fossil remnants of keratose demosponges. These putative fossils of keratose demosponges are preserved as automicritic clumps. They are morphologically distinguishable from microbial fabrics but similar to other spiculate sponge fossils, except that the skeletal elements consist of fibrous networks instead of assembled spicules. Consistent with the immunological behavior of sponges, these fibrous skeletons often form a rim at the edge of the automicritic aggregate, separating the inner part of the aggregate from foreign objects. To confirm the architecture of these fibrous networks, two fossil specimens and a modern thorectid sponge for comparison were processed for three-dimensional (3-D) reconstruction using serial grinding tomography. The resulting fossil reconstructions are three-dimensionally anastomosing, like modern keratose demosponges, but their irregular and nonhierarchical meshes indicate a likely verongid affinity, although a precise taxonomic conclusion cannot be made based on the skeletal architecture alone. This study is a preliminary effort, but an important start to identify fossil non-spicular demosponges in carbonates and to re-evaluate their fossilization potential.

Luo, Cui; Reitner, Joachim

2014-06-01

347

A comparative study of limited-angle cone-beam reconstruction methods for breast tomosynthesis  

International Nuclear Information System (INIS)

te the reconstruction results. It was found that for the phantoms with homogeneous background, the BP method resulted in less noisy tomosynthesized images and higher CNR values for masses than the SART and ML-convex methods. However, the two iterative methods provided greater contrast enhancement for both masses and calcification, sharper LOSF, and reduced interplane blurring and artifacts with better ASF behaviors for masses. For a contrast-detail phantom with heterogeneous tissue-mimicking background, the BP method had strong blurring artifacts along the x-ray source motion direction that obscured the contrast-detail objects, while the other two methods can remove the superimposed breast structures and significantly improve object conspicuity. With a properly selected relaxation parameter, the SART method with one iteration can provide tomosynthesized images comparable to those obtained from the ML-convex method with seven iterations, when BP results were used as initialization for both methods

348

Improving axial image reconstruction by off-centering ROI with data truncation and 3D weighted cone beam DBPF algorithm  

International Nuclear Information System (INIS)

We have proposed to improve the accuracy of axial image reconstruction by off-centering the region of interest (ROI) to be imaged and reconstructing the images using the 3D weighted cone beam (CB) filtered backprojection (CB-FBP) algorithm. By applying the 3D weighting scheme at each voxel within the off-centered object, the minimum cone angle of the ray out of the conjugate ray pair corresponding to the vast majority of the voxel can be effectively reduced, and thus reduce CB artifact in reconstructe