WorldWideScience

Sample records for b-spline nonrigid registration

  1. Non-Rigid Image Registration Algorithm Based on B-Splines Approximation

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hongying; ZHANG Jiawan; SUN Jizhou; SUN Yigang

    2007-01-01

    An intensity-based non-rigid registration algorithm is discussed, which uses Gaussian smoothing to constrain the transformation to be smooth, and thus preserves the topology of images. In view of the insufficiency of the uniform Gaussian filtering of the deformation field, an automatic and accurate non-rigid image registration method based on B-splines approximation is proposed. The regularization strategy is adopted by using multi-level B-splines approximation to regularize the dis-placement fields in a coarse-to-fine manner. Moreover, it assigns the different weights to the estimated displacements according to their reliabilities. In this way, the level of regularity can be adapted locally. Experiments were performed on both synthetic and real medical images of brain, and the results show that the proposed method improves the registration accuracy and robustness.

  2. Adaptive Parametrization of Multivariate B-splines for Image Registration

    DEFF Research Database (Denmark)

    Hansen, Michael Sass; Glocker, Benjamin; Navab, Nassir;

    2008-01-01

    We present an adaptive parametrization scheme for dynamic mesh refinement in the application of parametric image registration. The scheme is based on a refinement measure ensuring that the control points give an efficient representation of the warp fields, in terms of minimizing the registration...... cost function. In the current work we introduce multivariate B-splines as a novel alternative to the widely used tensor B-splines enabling us to make efficient use of the derived measure.The multivariate B-splines of order n are Cn- 1 smooth and are based on Delaunay configurations of arbitrary 2D or 3...... reside on a regular grid. In contrast, by efficient non- constrained placement of the knots, the multivariate B- splines are shown to give a good representation of inho- mogeneous objects in natural settings. The wide applicability of the method is illustrated through its application on medical data and...

  3. Multi-modality liver image registration based on multilevel B-splines free-form deformation and L-BFGS optimal algorithm

    Institute of Scientific and Technical Information of China (English)

    宋红; 李佳佳; 王树良; 马婧婷

    2014-01-01

    A new coarse-to-fine strategy was proposed for nonrigid registration of computed tomography (CT) and magnetic resonance (MR) images of a liver. This hierarchical framework consisted of an affine transformation and a B-splines free-form deformation (FFD). The affine transformation performed a rough registration targeting the mismatch between the CT and MR images. The B-splines FFD transformation performed a finer registration by correcting local motion deformation. In the registration algorithm, the normalized mutual information (NMI) was used as similarity measure, and the limited memory Broyden-Fletcher-Goldfarb-Shannon (L-BFGS) optimization method was applied for optimization process. The algorithm was applied to the fully automated registration of liver CT and MR images in three subjects. The results demonstrate that the proposed method not only significantly improves the registration accuracy but also reduces the running time, which is effective and efficient for nonrigid registration.

  4. Affine with B-Spline Registration based Retrieval using Distance Metrics

    Directory of Open Access Journals (Sweden)

    Swarnambiga AYYACHAMY

    2014-06-01

    Full Text Available Developing a two stage framework is the purpose dealt in this paper. This rely on the Affine transformation and B –Spline for registration of medical images as the first stage of the framework and retrieval of medical images using distance metrics as the second stage in the framework. Affine with B-Spline registration based retrieval methods have been dealt in this paper. Evaluation of the framework using images extracted from the Affine with B-Spline registration are applied for the retrieval of medical images performing registration based retrieval. Quantitative analysis is performed to show the registration based retrieval methods perform well with comparable results and presents a summary of the results obtained. This work brings three major advantages as conclusion. First, medical images are conveniently retrieved from the database for effective clinical comparison, diagnosis and verification and also serving as a guidance tool. Second, coping registration techniques with monomodal medical images for more detailed view of images. Third, driving and tracking the entire lifecycle of this medical process would be easier with this application which permits immediate access to all patients’ data stored in a medical repository. Conclusions drawn out of the proposed schemes are listed and justified.

  5. The effects of computed tomography image characteristics and knot spacing on the spatial accuracy of B-spline deformable image registration in the head and neck geometry

    NARCIS (Netherlands)

    Brouwer, Charlotte L.; Kierkels, Roel G. J.; van t Veld, Aart A.; Sijtsema, Nanna M.; Meertens, Harm

    2014-01-01

    Objectives: To explore the effects of computed tomography (CT) image characteristics and B-spline knot spacing (BKS) on the spatial accuracy of a B-spline deformable image registration (DIR) in the head-and-neck geometry. Methods: The effect of image feature content, image contrast, noise, and BKS o

  6. Nonrigid registration of myocardial perfusion MRI

    DEFF Research Database (Denmark)

    Ólafsdóttir, Hildur

    2005-01-01

    This paper describes a fully automatic registration of 10 multi-slice myocardial perfusion magnetic resonance image sequences. The registration of these sequences is crucial for the clinical interpretation, which currently is subjected to manual labour. The approach used in this study is a nonrigid...... registration algorithm based on free-form deformations due to Rueckert et al. Inspection of difference images from the wash-out part of the perfusion sequences indicates that a good registration accuracy is obtained....

  7. Efficient nonrigid registration using ranked order statistics

    DEFF Research Database (Denmark)

    Tennakoon, R.B.; Bab-Hadiashar, A.; de Bruijne, Marleen;

    2013-01-01

    of research. In this paper we propose a fast and accurate non-rigid registration method for intra-modality volumetric images. Our approach exploits the information provided by an order statistics based segmentation method, to find the important regions for registration and use an appropriate sampling scheme...

  8. Non-Rigid Medical Image Registration with Joint Histogram Estimation Based on Mutual Information

    Institute of Scientific and Technical Information of China (English)

    LU Xuesong; ZHANG Su; SU He; CHEN Yazhu

    2007-01-01

    A mutual information-based non-rigid medical image registration algorithm is presented. An approximate function of Harming windowed sinc is used as kernel function of partial volume (PV)interpolation to estimate the joint histogram, which is the key to calculating the mutual information. And a new method is proposed to compute the gradient of mutual information with respect to themodel parameters. The transformation of object is modeled by a free-form deformation (FFD) based on B-splines. The experiments on 3D synthetic and real image data show that the algorithm can con-verge at the global optimum and restrain the emergency of local extreme.

  9. Optimizing nonrigid registration performance between volumetric true 3D ultrasound images in image-guided neurosurgery

    Science.gov (United States)

    Ji, Songbai; Fan, Xiaoyao; Roberts, David W.; Hartov, Alex; Paulsen, Keith D.

    2011-03-01

    Compensating for brain shift as surgery progresses is important to ensure sufficient accuracy in patient-to-image registration in the operating room (OR) for reliable neuronavigation. Ultrasound has emerged as an important and practical imaging technique for brain shift compensation either by itself or through computational modeling that estimates whole-brain deformation. Using volumetric true 3D ultrasound (3DUS), it is possible to nonrigidly (e.g., based on B-splines) register two temporally different 3DUS images directly to generate feature displacement maps for data assimilation in the biomechanical model. Because of a large amount of data and number of degrees-of-freedom (DOFs) involved, however, a significant computational cost may be required that can adversely influence the clinical feasibility of the technique for efficiently generating model-updated MR (uMR) in the OR. This paper parametrically investigates three B-splines registration parameters and their influence on the computational cost and registration accuracy: number of grid nodes along each direction, floating image volume down-sampling rate, and number of iterations. A simulated rigid body displacement field was employed as a ground-truth against which the accuracy of displacements generated from the B-splines nonrigid registration was compared. A set of optimal parameters was then determined empirically that result in a registration computational cost of less than 1 min and a sub-millimetric accuracy in displacement measurement. These resulting parameters were further applied to a clinical surgery case to demonstrate their practical use. Our results indicate that the optimal set of parameters result in sufficient accuracy and computational efficiency in model computation, which is important for future application of the overall biomechanical modeling to generate uMR for image-guidance in the OR.

  10. A comparison of thin-plate splines with automatic correspondences and B-splines with uniform grids for multimodal prostate registration

    Science.gov (United States)

    Mitra, Jhimli; Marti, Robert; Oliver, Arnau; Llado, Xavier; Vilanova, Joan C.; Meriaudeau, Fabrice

    2011-03-01

    This paper provides a comparison of spline-based registration methods applied to register interventional Trans Rectal Ultrasound (TRUS) and pre-acquired Magnetic Resonance (MR) prostate images for needle guided prostate biopsy. B-splines and Thin-plate Splines (TPS) are the most prevalent spline-based approaches to achieve deformable registration. Pertaining to the strategic selection of correspondences for the TPS registration, we use an automatic method already proposed in our previous work to generate correspondences in the MR and US prostate images. The method exploits the prostate geometry with the principal components of the segmented prostate as the underlying framework and involves a triangulation approach. The correspondences are generated with successive refinements and Normalized Mutual Information (NMI) is employed to determine the optimal number of correspondences required to achieve TPS registration. B-spline registration with successive grid refinements are consecutively applied for a significant comparison of the impact of the strategically chosen correspondences on the TPS registration against the uniform B-spline control grids. The experimental results are validated on 4 patient datasets. Dice Similarity Coefficient (DSC) is used as a measure of the registration accuracy. Average DSC values of 0.97+/-0.01 and 0.95+/-0.03 are achieved for the TPS and B-spline registrations respectively. B-spline registration is observed to be more computationally expensive than the TPS registration with average execution times of 128.09 +/- 21.7 seconds and 62.83 +/- 32.77 seconds respectively for images with maximum width of 264 pixels and a maximum height of 211 pixels.

  11. Optimized imaging using non-rigid registration

    Energy Technology Data Exchange (ETDEWEB)

    Berkels, Benjamin, E-mail: berkels@aices.rwth-aachen.de [Interdisciplinary Mathematics Institute, 1523 Greene Street, University of South Carolina, Columbia, SC 29208 (United States); Binev, Peter, E-mail: binev@math.sc.edu [Interdisciplinary Mathematics Institute, 1523 Greene Street, University of South Carolina, Columbia, SC 29208 (United States); Department of Mathematics, 1523 Greene Street, University of South Carolina, Columbia, SC 29208 (United States); Blom, Douglas A., E-mail: doug.blom@sc.edu [NanoCenter, 1212 Greene Street, University of South Carolina, Columbia, SC 29208 (United States); Dahmen, Wolfgang, E-mail: dahmen@igpm.rwth-aachen.de [Interdisciplinary Mathematics Institute, 1523 Greene Street, University of South Carolina, Columbia, SC 29208 (United States); Institut für Geometrie und Praktische Mathematik, RWTH Aachen, Templergraben 55, 52056 Aachen (Germany); Sharpley, Robert C., E-mail: rcsharpley@gmail.com [Interdisciplinary Mathematics Institute, 1523 Greene Street, University of South Carolina, Columbia, SC 29208 (United States); Department of Mathematics, 1523 Greene Street, University of South Carolina, Columbia, SC 29208 (United States); Vogt, Thomas, E-mail: tvogt@mailbox.sc.edu [Interdisciplinary Mathematics Institute, 1523 Greene Street, University of South Carolina, Columbia, SC 29208 (United States); NanoCenter, 1212 Greene Street, University of South Carolina, Columbia, SC 29208 (United States); Department of Chemistry and Biochemistry, 631 Sumter Street, University of South Carolina, Columbia, SC 29208 (United States)

    2014-03-01

    The extraordinary improvements of modern imaging devices offer access to data with unprecedented information content. However, widely used image processing methodologies fall far short of exploiting the full breadth of information offered by numerous types of scanning probe, optical, and electron microscopies. In many applications, it is necessary to keep measurement intensities below a desired threshold. We propose a methodology for extracting an increased level of information by processing a series of data sets suffering, in particular, from high degree of spatial uncertainty caused by complex multiscale motion during the acquisition process. An important role is played by a non-rigid pixel-wise registration method that can cope with low signal-to-noise ratios. This is accompanied by formulating objective quality measures which replace human intervention and visual inspection in the processing chain. Scanning transmission electron microscopy of siliceous zeolite material exhibits the above-mentioned obstructions and therefore serves as orientation and a test of our procedures. - Highlights: • Developed a new process for extracting more information from a series of STEM images. • An objective non-rigid registration process copes with distortions. • Images of zeolite Y show retrieval of all information available from the data set. • Quantitative measures of registration quality were implemented. • Applicable to any serially acquired data, e.g. STM, AFM, STXM, etc.

  12. 3D non-rigid registration using surface and local salient features for transrectal ultrasound image-guided prostate biopsy

    Science.gov (United States)

    Yang, Xiaofeng; Akbari, Hamed; Halig, Luma; Fei, Baowei

    2011-03-01

    We present a 3D non-rigid registration algorithm for the potential use in combining PET/CT and transrectal ultrasound (TRUS) images for targeted prostate biopsy. Our registration is a hybrid approach that simultaneously optimizes the similarities from point-based registration and volume matching methods. The 3D registration is obtained by minimizing the distances of corresponding points at the surface and within the prostate and by maximizing the overlap ratio of the bladder neck on both images. The hybrid approach not only capture deformation at the prostate surface and internal landmarks but also the deformation at the bladder neck regions. The registration uses a soft assignment and deterministic annealing process. The correspondences are iteratively established in a fuzzy-to-deterministic approach. B-splines are used to generate a smooth non-rigid spatial transformation. In this study, we tested our registration with pre- and postbiopsy TRUS images of the same patients. Registration accuracy is evaluated using manual defined anatomic landmarks, i.e. calcification. The root-mean-squared (RMS) of the difference image between the reference and floating images was decreased by 62.6+/-9.1% after registration. The mean target registration error (TRE) was 0.88+/-0.16 mm, i.e. less than 3 voxels with a voxel size of 0.38×0.38×0.38 mm3 for all five patients. The experimental results demonstrate the robustness and accuracy of the 3D non-rigid registration algorithm.

  13. Non-rigid image registration using bone growth model

    DEFF Research Database (Denmark)

    Bro-Nielsen, Morten; Gramkow, Claus; Kreiborg, Sven;

    1997-01-01

    Non-rigid registration has traditionally used physical models like elasticity and fluids. These models are very seldom valid models of the difference between the registered images. This paper presents a non-rigid registration algorithm, which uses a model of bone growth as a model of the change b...

  14. A cubic B-spline-based hybrid registration of lung CT images for a dynamic airway geometric model with large deformation

    International Nuclear Information System (INIS)

    The goal of this study is to develop a matching algorithm that can handle large geometric changes in x-ray computed tomography (CT)-derived lung geometry occurring during deep breath maneuvers. These geometric relationships are further utilized to build a dynamic lung airway model for computational fluid dynamics (CFD) studies of pulmonary air flow. The proposed algorithm is based on a cubic B-spline-based hybrid registration framework that incorporates anatomic landmark information with intensity patterns. A sequence of invertible B-splines is composed in a multiresolution framework to ensure local invertibility of the large deformation transformation and a physiologically meaningful similarity measure is adopted to compensate for changes in voxel intensity due to inflation. Registrations are performed using the proposed approach to match six pairs of 3D CT human lung datasets. Results show that the proposed approach has the ability to match the intensity pattern and the anatomical landmarks, and ensure local invertibility for large deformation transformations. Statistical results also show that the proposed hybrid approach yields significantly improved results as compared with approaches using either landmarks or intensity alone.

  15. A cubic B-spline-based hybrid registration of lung CT images for a dynamic airway geometric model with large deformation

    Energy Technology Data Exchange (ETDEWEB)

    Yin Youbing; Lin, Ching-Long [Department of Mechanical and Industrial Engineering, University of Iowa, Iowa City, IA 52242 (United States); Hoffman, Eric A [Department of Radiology, University of Iowa, Iowa City, IA 52242 (United States); Ding Kai; Reinhardt, Joseph M, E-mail: ching-long-lin@uiowa.edu [Department of Biomedical Engineering, University of Iowa, Iowa City, IA 52242 (United States)

    2011-01-07

    The goal of this study is to develop a matching algorithm that can handle large geometric changes in x-ray computed tomography (CT)-derived lung geometry occurring during deep breath maneuvers. These geometric relationships are further utilized to build a dynamic lung airway model for computational fluid dynamics (CFD) studies of pulmonary air flow. The proposed algorithm is based on a cubic B-spline-based hybrid registration framework that incorporates anatomic landmark information with intensity patterns. A sequence of invertible B-splines is composed in a multiresolution framework to ensure local invertibility of the large deformation transformation and a physiologically meaningful similarity measure is adopted to compensate for changes in voxel intensity due to inflation. Registrations are performed using the proposed approach to match six pairs of 3D CT human lung datasets. Results show that the proposed approach has the ability to match the intensity pattern and the anatomical landmarks, and ensure local invertibility for large deformation transformations. Statistical results also show that the proposed hybrid approach yields significantly improved results as compared with approaches using either landmarks or intensity alone.

  16. Non-rigid registration by geometry-constrained diffusion

    DEFF Research Database (Denmark)

    Andresen, Per Rønsholt; Nielsen, Mads

    2001-01-01

    Assume that only partial knowledge about a non-rigid registration is given: certain points, curves, or surfaces in one 3D image are known to map to certain points, curves, or surfaces in another 3D image. In trying to identify the non-rigid registration field, we face a generalized aperture problem...... since along the curves and surfaces, {\\$\\backslash\\$em point} correspondences are not given. We will advocate the viewpoint that the aperture and the 3D interpolation problem may be solved {\\$\\backslash\\$em simultaneously} by finding the {\\$\\backslash\\$em simplest} displacement field. This is obtained...... by a geometry-constrained diffusion, which in a precise sense yields the simplest displacement field. The point registration obtained may be used for segmentation, growth modeling, shape analysis, or kinematic interpolation. The algorithm applies to geometrical objects of any dimensionality. We may thus keep...

  17. Digital correction of motion artefacts in microscopy image sequences collected from living animals using rigid and nonrigid registration.

    Science.gov (United States)

    Lorenz, K S; Salama, P; Dunn, K W; Delp, E J

    2012-02-01

    Digital image analysis is a fundamental component of quantitative microscopy. However, intravital microscopy presents many challenges for digital image analysis. In general, microscopy volumes are inherently anisotropic, suffer from decreasing contrast with tissue depth, lack object edge detail and characteristically have low signal levels. Intravital microscopy introduces the additional problem of motion artefacts, resulting from respiratory motion and heartbeat from specimens imaged in vivo. This paper describes an image registration technique for use with sequences of intravital microscopy images collected in time-series or in 3D volumes. Our registration method involves both rigid and nonrigid components. The rigid registration component corrects global image translations, whereas the nonrigid component manipulates a uniform grid of control points defined by B-splines. Each control point is optimized by minimizing a cost function consisting of two parts: a term to define image similarity, and a term to ensure deformation grid smoothness. Experimental results indicate that this approach is promising based on the analysis of several image volumes collected from the kidney, lung and salivary gland of living rodents.

  18. Learning Nonrigid Deformations for Constrained Multi-modal Image Registration

    OpenAIRE

    Onofrey, John A.; Staib, Lawrence H.; Papademetris, Xenophon

    2013-01-01

    We present a new strategy to constrain nonrigid registrations of multi-modal images using a low-dimensional statistical deformation model and test this in registering pre-operative and post-operative images from epilepsy patients. For those patients who may undergo surgical resection for treatment, the current gold-standard to identify regions of seizure involves craniotomy and implantation of intracranial electrodes. To guide surgical resection, surgeons utilize pre-op anat...

  19. A Comparison of FFD-based Nonrigid Registration and AAMs Applied to Myocardial Perfusion MRI

    DEFF Research Database (Denmark)

    Ólafsdóttir, Hildur; Stegmann, Mikkel Bille; Ersbøll, Bjarne Kjær;

    2006-01-01

    Little work has been done on comparing the performance of statistical model-based approaches and nonrigid registration algorithms. This paper deals with the qualitative and quantitative comparison of active appearance models (AAMs) and a nonrigid registration algorithm based on free-form deformat......Little work has been done on comparing the performance of statistical model-based approaches and nonrigid registration algorithms. This paper deals with the qualitative and quantitative comparison of active appearance models (AAMs) and a nonrigid registration algorithm based on free......-form deformations (FFDs). AAMs are known to be much faster than nonrigid registration algorithms. On the other hand nonrigid registration algorithms are independent of a training set as required to build an AAM. To obtain a further comparison of the two methods, they are both applied to automatically register multi...

  20. Personalized x-ray reconstruction of the proximal femur via a non-rigid 2D-3D registration

    Science.gov (United States)

    Yu, Weimin; Zysset, Philippe; Zheng, Guoyan

    2015-03-01

    In this paper we present a new approach for a personalized X-ray reconstruction of the proximal femur via a non-rigid registration of a 3D volumetric template to 2D calibrated C-arm images. The 2D-3D registration is done with a hierarchical two-stage strategy: the global scaled rigid registration stage followed by a regularized deformable b-spline registration stage. In both stages, a set of control points with uniform spacing are placed over the domain of the 3D volumetric template and the registrations are driven by computing updated positions of these control points, which then allows to accurately register the 3D volumetric template to the reference space of the C-arm images. Comprehensive experiments on simulated images, on images of cadaveric femurs and on clinical datasets are designed and conducted to evaluate the performance of the proposed approach. Quantitative and qualitative evaluation results are given, which demonstrate the efficacy of the present approach.

  1. Non-rigid multi-modal registration on the GPU

    Science.gov (United States)

    Vetter, Christoph; Guetter, Christoph; Xu, Chenyang; Westermann, Rüdiger

    2007-03-01

    Non-rigid multi-modal registration of images/volumes is becoming increasingly necessary in many medical settings. While efficient registration algorithms have been published, the speed of the solutions is a problem in clinical applications. Harnessing the computational power of graphics processing unit (GPU) for general purpose computations has become increasingly popular in order to speed up algorithms further, but the algorithms have to be adapted to the data-parallel, streaming model of the GPU. This paper describes the implementation of a non-rigid, multi-modal registration using mutual information and the Kullback-Leibler divergence between observed and learned joint intensity distributions. The entire registration process is implemented on the GPU, including a GPU-friendly computation of two-dimensional histograms using vertex texture fetches as well as an implementation of recursive Gaussian filtering on the GPU. Since the computation is performed on the GPU, interactive visualization of the registration process can be done without bus transfer between main memory and video memory. This allows the user to observe the registration process and to evaluate the result more easily. Two hybrid approaches distributing the computation between the GPU and CPU are discussed. The first approach uses the CPU for lower resolutions and the GPU for higher resolutions, the second approach uses the GPU to compute a first approximation to the registration that is used as starting point for registration on the CPU using double-precision. The results of the CPU implementation are compared to the different approaches using the GPU regarding speed as well as image quality. The GPU performs up to 5 times faster per iteration than the CPU implementation.

  2. Optimal grid point selection for improved nonrigid medical image registration

    Science.gov (United States)

    Fookes, Clinton; Maeder, Anthony

    2004-05-01

    Non-rigid image registration is an essential tool required for overcoming the inherent local anatomical variations that exist between medical images acquired from different individuals or atlases, among others. This type of registration defines a deformation field that gives a translation or mapping for every pixel in the image. One popular local approach for estimating this deformation field, known as block matching, is where a grid of control points are defined on an image and are each taken as the centre of a small window. These windows are then translated in the second image to maximise a local similarity criterion. This generates two corresponding sets of control points for the two images, yielding a sparse deformation field. This sparse field can then be propagated to the entire image using well known methods such as the thin-plate spline warp or simple Gaussian convolution. Previous block matching procedures all utilise uniformly distributed grid points. This results in the generation of a sparse deformation field containing displacement estimates at uniformly spaced locations. This neglects to make use of the evidence that block matching results are dependent on the amount of local information content. That is, results are better in regions of high information when compared to regions of low information. Consequently, this paper presents a solution to this drawback by proposing the use of a Reversible Jump Markov Chain Monte Carlo (RJMCMC) statistical procedure to optimally select grid points of interest. These grid points have a greater concentration in regions of high information and a lower concentration in regions of small information. Results show that non-rigid registration can by improved by using optimally selected grid points of interest.

  3. Nonrigid Registration of Monomodal MRI Using Linear Viscoelastic Model

    Directory of Open Access Journals (Sweden)

    Jian Yang

    2014-01-01

    Full Text Available This paper describes a method for nonrigid registration of monomodal MRI based on physical laws. The proposed method assumes that the properties of image deformations are like those of viscoelastic matter, which exhibits the properties of both an elastic solid and a viscous fluid. Therefore, the deformation fields of the deformed image are constrained by both sets of properties. After global registration, the local shape variations are assumed to have the properties of the Maxwell model of linear viscoelasticity, and the deformation fields are constrained by the corresponding partial differential equations. To speed up the registration, an adaptive force is introduced according to the maximum displacement of each iteration. Both synthetic datasets and real datasets are used to evaluate the proposed method. We compare the results of the linear viscoelastic model with those of the fluid model on the basis of both the standard and adaptive forces. The results demonstrate that the adaptive force increases in both models and that the linear viscoelastic model improves the registration accuracy.

  4. Learning intervention-induced deformations for non-rigid MR-CT registration and electrode localization in epilepsy patients.

    Science.gov (United States)

    Onofrey, John A; Staib, Lawrence H; Papademetris, Xenophon

    2016-01-01

    This paper describes a framework for learning a statistical model of non-rigid deformations induced by interventional procedures. We make use of this learned model to perform constrained non-rigid registration of pre-procedural and post-procedural imaging. We demonstrate results applying this framework to non-rigidly register post-surgical computed tomography (CT) brain images to pre-surgical magnetic resonance images (MRIs) of epilepsy patients who had intra-cranial electroencephalography electrodes surgically implanted. Deformations caused by this surgical procedure, imaging artifacts caused by the electrodes, and the use of multi-modal imaging data make non-rigid registration challenging. Our results show that the use of our proposed framework to constrain the non-rigid registration process results in significantly improved and more robust registration performance compared to using standard rigid and non-rigid registration methods. PMID:26900569

  5. Learning intervention-induced deformations for non-rigid MR-CT registration and electrode localization in epilepsy patients

    Directory of Open Access Journals (Sweden)

    John A. Onofrey

    2016-01-01

    Full Text Available This paper describes a framework for learning a statistical model of non-rigid deformations induced by interventional procedures. We make use of this learned model to perform constrained non-rigid registration of pre-procedural and post-procedural imaging. We demonstrate results applying this framework to non-rigidly register post-surgical computed tomography (CT brain images to pre-surgical magnetic resonance images (MRIs of epilepsy patients who had intra-cranial electroencephalography electrodes surgically implanted. Deformations caused by this surgical procedure, imaging artifacts caused by the electrodes, and the use of multi-modal imaging data make non-rigid registration challenging. Our results show that the use of our proposed framework to constrain the non-rigid registration process results in significantly improved and more robust registration performance compared to using standard rigid and non-rigid registration methods.

  6. Nonrigid registration of carotid ultrasound and MR images using a "twisting and bending" model

    Science.gov (United States)

    Nanayakkara, Nuwan D.; Chiu, Bernard; Samani, Abbas; Spence, J. David; Parraga, Grace; Samarabandu, Jagath; Fenster, Aaron

    2008-03-01

    Atherosclerosis at the carotid bifurcation resulting in cerebral emboli is a major cause of ischemic stroke. Most strokes associated with carotid atherosclerosis can be prevented by lifestyle/dietary changes and pharmacological treatments if identified early by monitoring carotid plaque changes. Plaque composition information from magnetic resonance (MR) carotid images and dynamic characteristics information from 3D ultrasound (US) are necessary for developing and validating US imaging tools to identify vulnerable carotid plaques. Combining these images requires nonrigid registration to correct the non-linear miss-alignments caused by relative twisting and bending in the neck due to different head positions during the two image acquisitions sessions. The high degree of freedom and large number of parameters associated with existing nonrigid image registration methods causes several problems including unnatural plaque morphology alteration, computational complexity, and low reliability. Our approach was to model the normal movement of the neck using a "twisting and bending model" with only six parameters for nonrigid registration. We evaluated our registration technique using intra-subject in-vivo 3D US and 3D MR carotid images acquired on the same day. We calculated the Mean Registration Error (MRE) between the segmented vessel surfaces in the target image and the registered image using a distance-based error metric after applying our "twisting bending model" based nonrigid registration algorithm. We achieved an average registration error of 1.33+/-0.41mm using our nonrigid registration technique. Visual inspection of segmented vessel surfaces also showed a substantial improvement of alignment with our non-rigid registration technique.

  7. MUTUAL INFORMATION BASED 3D NON-RIGID REGISTRATION OF CT/MR ABDOMEN IMAGES

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A mutual information based 3D non-rigid registration approach was proposed for the registration of deformable CT/MR body abdomen images. The Parzen Windows Density Estimation (PWDE) method is adopted to calculate the mutual information between the two modals of CT and MRI abdomen images. By maximizing MI between the CT and MR volume images, the overlapping part of them reaches the biggest, which means that the two body images of CT and MR matches best to each other. Visible Human Project (VHP) Male abdomen CT and MRI Data are used as experimental data sets. The experimental results indicate that this approach of non-rigid 3D registration of CT/MR body abdominal images can be achieved effectively and automatically, without any prior processing procedures such as segmentation and feature extraction, but has a main drawback of very long computation time. Key words: medical image registration; multi-modality; mutual information; non-rigid; Parzen window density estimation

  8. Non-rigid registration of volumetric images using ranked order statistics

    DEFF Research Database (Denmark)

    Tennakoon, Ruwan; Bab-Hadiashar, Alireza; Cao, Zhenwei;

    2014-01-01

    Non-rigid image registration techniques using intensity based similarity measures are widely used in medical imaging applications. Due to high computational complexities of these techniques, particularly for volumetric images, finding appropriate registration methods to both reduce the computation...... burden and increase the registration accuracy has become an intensive area of research. In this paper we propose a fast and accurate non-rigid registration method for intra-modality volumetric images. Our approach exploits the information provided by an order statistics based segmentation method, to find...... on registration of endinhale to end-exhale lung CT scan pairs, with expert annotated landmarks, show that the new method is both faster and more accurate than the state of the art sampling based techniques, particularly for registration of images with large deformations....

  9. [Research on non-rigid medical image registration algorithm based on SIFT feature extraction].

    Science.gov (United States)

    Wang, Anna; Lu, Dan; Wang, Zhe; Fang, Zhizhen

    2010-08-01

    In allusion to non-rigid registration of medical images, the paper gives a practical feature points matching algorithm--the image registration algorithm based on the scale-invariant features transform (Scale Invariant Feature Transform, SIFT). The algorithm makes use of the image features of translation, rotation and affine transformation invariance in scale space to extract the image feature points. Bidirectional matching algorithm is chosen to establish the matching relations between the images, so the accuracy of image registrations is improved. On this basis, affine transform is chosen to complement the non-rigid registration, and normalized mutual information measure and PSO optimization algorithm are also chosen to optimize the registration process. The experimental results show that the method can achieve better registration results than the method based on mutual information.

  10. Robust non-rigid point set registration using student's-t mixture model.

    Directory of Open Access Journals (Sweden)

    Zhiyong Zhou

    Full Text Available The Student's-t mixture model, which is heavily tailed and more robust than the Gaussian mixture model, has recently received great attention on image processing. In this paper, we propose a robust non-rigid point set registration algorithm using the Student's-t mixture model. Specifically, first, we consider the alignment of two point sets as a probability density estimation problem and treat one point set as Student's-t mixture model centroids. Then, we fit the Student's-t mixture model centroids to the other point set which is treated as data. Finally, we get the closed-form solutions of registration parameters, leading to a computationally efficient registration algorithm. The proposed algorithm is especially effective for addressing the non-rigid point set registration problem when significant amounts of noise and outliers are present. Moreover, less registration parameters have to be set manually for our algorithm compared to the popular coherent points drift (CPD algorithm. We have compared our algorithm with other state-of-the-art registration algorithms on both 2D and 3D data with noise and outliers, where our non-rigid registration algorithm showed accurate results and outperformed the other algorithms.

  11. Learning intervention-induced deformations for non-rigid MR-CT registration and electrode localization in epilepsy patients

    OpenAIRE

    Onofrey, John A.; Staib, Lawrence H.; Xenophon Papademetris

    2016-01-01

    This paper describes a framework for learning a statistical model of non-rigid deformations induced by interventional procedures. We make use of this learned model to perform constrained non-rigid registration of pre-procedural and post-procedural imaging. We demonstrate results applying this framework to non-rigidly register post-surgical computed tomography (CT) brain images to pre-surgical magnetic resonance images (MRIs) of epilepsy patients who had intra-cranial electroencephalography el...

  12. Evaluation and validation methods for intersubject nonrigid 3D image registration of the human brain

    Science.gov (United States)

    Guo, Ting; Starreveld, Yves P.; Peters, Terry M.

    2005-04-01

    This work presents methodologies for assessing the accuracy of non-rigid intersubject registration algorithms from both qualitative and quantitative perspectives. The first method was based on a set of 43 anatomical landmarks. MRI brain images of 12 subjects were non-rigidly registered to the standard MRI dataset. The "gold-standard" coordinates of the 43 landmarks in the target were estimated by averaging their coordinates after 6 tagging sessions. The Euclidean distance between each landmark of a subject after warping to the reference space and the homologous "gold-standard" landmark on the reference image was considered as the registration error. Another method based on visual inspection software displaying the spatial change of colour-coded spheres, before and after warping, was also developed to evaluate the performance of the non-rigid warping algorithms within the homogeneous regions in the deep-brain. Our methods were exemplified by assessing and comparing the accuracy of two intersubject non-rigid registration approaches, AtamaiWarp and ANIMAL algorithms. From the first method, the average registration error was 1.04mm +/- 0.65mm for AtamaiWarp, and 1.59mm +/- 1.47mm for ANIMAL. With maximum registration errors of 2.78mm and 3.90mm respectively, AtamaiWarp and ANIMAL located 58% and 35% landmarks respectively with registration errors less than 1mm. A paired t-test showed that the differences in registration error between AtamaiWarp and ANIMAL were significant (P ANIMAL, also provides more accurate results. From the second method, both algorithms treated the interior of homogeneous regions in an appropriate manner.

  13. An information theoretic approach for non-rigid image registration using voxel class probabilities.

    Science.gov (United States)

    D'Agostino, Emiliano; Maes, Frederik; Vandermeulen, Dirk; Suetens, Paul

    2006-06-01

    We propose two information theoretic similarity measures that allow to incorporate tissue class information in non-rigid image registration. The first measure assumes that tissue class probabilities have been assigned to each of the images to be registered by prior segmentation of both of them. One image is then non-rigidly deformed to match the other such that the fuzzy overlap of corresponding voxel object labels becomes similar to the ideal case whereby the tissue probability maps of both images are identical. Image similarity is assessed during registration by the divergence between the ideal and actual joint class probability distributions of both images. A second registration measure is proposed that applies in case a segmentation is available for only one of the images, for instance an atlas image that is to be matched to a study image to guide the segmentation thereof. Intensities in one image are matched to the fuzzy class labels in the other image by minimizing the conditional entropy of the intensities in the first image given the class labels in the second image. We derive analytic expressions for the gradient of each measure with respect to individual voxel displacements to derive a force field that drives the registration process, which is regularized by a viscous fluid model. The performance of the class-based measures is evaluated in the context of non-rigid inter-subject registration and atlas-based segmentation of MR brain images and compared with maximization of mutual information using only intensity information. Our results demonstrate that incorporation of class information in the registration measure significantly improves the overlap between corresponding tissue classes after non-rigid matching. The methods proposed here open new perspectives for integrating segmentation and registration in a single process, whereby the output of one is used to guide the other.

  14. An accurate 3D shape context based non-rigid registration method for mouse whole-body skeleton registration

    Science.gov (United States)

    Xiao, Di; Zahra, David; Bourgeat, Pierrick; Berghofer, Paula; Acosta Tamayo, Oscar; Wimberley, Catriona; Gregoire, Marie C.; Salvado, Olivier

    2011-03-01

    Small animal image registration is challenging because of its joint structure, and posture and position difference in each acquisition without a standard scan protocol. In this paper, we face the issue of mouse whole-body skeleton registration from CT images. A novel method is developed for analyzing mouse hind-limb and fore-limb postures based on geodesic path descriptor and then registering the major skeletons and fore limb skeletons initially by thin-plate spline (TPS) transform based on the obtained geodesic paths and their enhanced correspondence fields. A target landmark correction method is proposed for improving the registration accuracy of the improved 3D shape context non-rigid registration method we previously proposed. A novel non-rigid registration framework, combining the skeleton posture analysis, geodesic path based initial alignment and 3D shape context model, is proposed for mouse whole-body skeleton registration. The performance of the proposed methods and framework was tested on 12 pairs of mouse whole-body skeletons. The experimental results demonstrated the flexibility, stability and accuracy of the proposed framework for automatic mouse whole body skeleton registration.

  15. Improved dosimetry for targeted radionuclide therapy using nonrigid registration on sequential SPECT images

    Energy Technology Data Exchange (ETDEWEB)

    Ao, Edwin C. I.; Mok, Greta S. P., E-mail: gretamok@umac.mo [Biomedical Imaging Laboratory, Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Macau SAR (China); Wu, Nien-Yun [Department of Biomedical Imaging and Radiological Sciences, National Yang Ming University, Taipei 112, Taiwan and Department of Nuclear Medicine, Taipei Veterans General Hospital, Taipei 112, Taiwan (China); Wang, Shyh-Jen [Department of Nuclear Medicine, Taipei Veterans General Hospital, Taipei 112, Taiwan (China); Song, Na [Department of Nuclear Medicine, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York 10461 (United States)

    2015-02-15

    Purpose: Voxel-level and patient-specific 3D dosimetry for targeted radionuclide therapy (TRT) typically involves serial nuclear medicine scans. Misalignment of the images can result in reduced dosimetric accuracy. Since the scans are typically performed over a period of several days, there will be patient movement between scans and possible nonrigid organ deformation. This work aims to implement and evaluate the use of nonrigid image registration on a series of quantitative SPECT (QSPECT) images for TRT dosimetry. Methods: A population of 4D extended cardiac torso phantoms, comprised of three In-111 Zevalin biokinetics models and three anatomical variations, was generated based on the patient data. The authors simulated QSPECT acquisitions at five time points. At each time point, individual organ and whole-body deformation between scans were modeled by translating/rotating organs and the body up to 5°/voxels, keeping ≤5% difference in organ volume. An analytical projector was used to generate realistic noisy projections for a medium energy general purpose collimator. Projections were reconstructed using OS-EM algorithm with geometric collimator detector response, attenuation, and scatter corrections. The QSPECT images were registered using organ-based nonrigid image registration method. The cumulative activity in each voxel was obtained by integrating the activity over time. Dose distribution images were obtained by convolving the cumulative activity images with a Y-90 dose kernel. Dose volume histograms (DVHs) for organs-of-interest were analyzed. Results: After nonrigid registration, the mean differences in organ doses compared to the case without misalignment were improved from (−15.50 ± 5.59)% to (−2.12 ± 1.05)% and (−7.28 ± 2.30)% to (−0.23 ± 0.71)% for the spleen and liver, respectively. For all organs, the cumulative DVHs showed improvement after nonrigid registration and the normalized absolute error of differential DVHs ranged from 6.79% to

  16. 3D nonrigid medical image registration using a new information theoretic measure

    International Nuclear Information System (INIS)

    This work presents a novel method for the nonrigid registration of medical images based on the Arimoto entropy, a generalization of the Shannon entropy. The proposed method employed the Jensen–Arimoto divergence measure as a similarity metric to measure the statistical dependence between medical images. Free-form deformations were adopted as the transformation model and the Parzen window estimation was applied to compute the probability distributions. A penalty term is incorporated into the objective function to smooth the nonrigid transformation. The goal of registration is to optimize an objective function consisting of a dissimilarity term and a penalty term, which would be minimal when two deformed images are perfectly aligned using the limited memory BFGS optimization method, and thus to get the optimal geometric transformation. To validate the performance of the proposed method, experiments on both simulated 3D brain MR images and real 3D thoracic CT data sets were designed and performed on the open source elastix package. For the simulated experiments, the registration errors of 3D brain MR images with various magnitudes of known deformations and different levels of noise were measured. For the real data tests, four data sets of 4D thoracic CT from four patients were selected to assess the registration performance of the method, including ten 3D CT images for each 4D CT data covering an entire respiration cycle. These results were compared with the normalized cross correlation and the mutual information methods and show a slight but true improvement in registration accuracy. (paper)

  17. 3D nonrigid medical image registration using a new information theoretic measure

    Science.gov (United States)

    Li, Bicao; Yang, Guanyu; Coatrieux, Jean Louis; Li, Baosheng; Shu, Huazhong

    2015-11-01

    This work presents a novel method for the nonrigid registration of medical images based on the Arimoto entropy, a generalization of the Shannon entropy. The proposed method employed the Jensen-Arimoto divergence measure as a similarity metric to measure the statistical dependence between medical images. Free-form deformations were adopted as the transformation model and the Parzen window estimation was applied to compute the probability distributions. A penalty term is incorporated into the objective function to smooth the nonrigid transformation. The goal of registration is to optimize an objective function consisting of a dissimilarity term and a penalty term, which would be minimal when two deformed images are perfectly aligned using the limited memory BFGS optimization method, and thus to get the optimal geometric transformation. To validate the performance of the proposed method, experiments on both simulated 3D brain MR images and real 3D thoracic CT data sets were designed and performed on the open source elastix package. For the simulated experiments, the registration errors of 3D brain MR images with various magnitudes of known deformations and different levels of noise were measured. For the real data tests, four data sets of 4D thoracic CT from four patients were selected to assess the registration performance of the method, including ten 3D CT images for each 4D CT data covering an entire respiration cycle. These results were compared with the normalized cross correlation and the mutual information methods and show a slight but true improvement in registration accuracy.

  18. Non-rigid registration by geometry-constrained diffusion

    DEFF Research Database (Denmark)

    Andresen, Per Rønsholt; Nielsen, Mads

    1999-01-01

    are not given. We will advocate the viewpoint that the aperture and the 3D interpolation problem may be solved simultaneously by finding the simplest displacement field. This is obtained by a geometry-constrained diffusion which yields the simplest displacement field in a precise sense. The point registration...

  19. B-spline techniques for volatility modeling

    OpenAIRE

    Corlay, Sylvain

    2013-01-01

    This paper is devoted to the application of B-splines to volatility modeling, specifically the calibration of the leverage function in stochastic local volatility models and the parameterization of an arbitrage-free implied volatility surface calibrated to sparse option data. We use an extension of classical B-splines obtained by including basis functions with infinite support. We first come back to the application of shape-constrained B-splines to the estimation of conditional expectations, ...

  20. Free-form image registration of human cochlear μCT data using skeleton similarity as anatomical prior

    DEFF Research Database (Denmark)

    Kjer, Hans Martin; Fagertun, Jens; Vera, Sergio;

    2016-01-01

    Better understanding of the anatomical variability of the human cochlear is important for the design and function of Cochlear Implants. Proper non-rigid alignment of high-resolution cochlear μCT data is a challenge for the typical cubic B-spline registration model. In this paper we study one way...... of incorporating skeleton-based similarity as an anatomical registration prior. We extract a centerline skeleton of the cochlear spiral, and generate corresponding parametric pseudo-landmarks between samples. These correspondences are included in the cost function of a typical cubic B-spline registration model...

  1. Multi-modal 2D-3D non-rigid registration

    Science.gov (United States)

    Prümmer, M.; Hornegger, J.; Pfister, M.; Dörfler, A.

    2006-03-01

    In this paper, we propose a multi-modal non-rigid 2D-3D registration technique. This method allows a non-rigid alignment of a patient pre-operatively computed tomography (CT) to few intra operatively acquired fluoroscopic X-ray images obtained with a C-arm system. This multi-modal approach is especially focused on the 3D alignment of high contrast reconstructed volumes with intra-interventional low contrast X-ray images in order to make use of up-to-date information for surgical guidance and other interventions. The key issue of non-rigid 2D-3D registration is how to define the distance measure between high contrast 3D data and low contrast 2D projections. In this work, we use algebraic reconstruction theory to handle this problem. We modify the Euler-Lagrange equation by introducing a new 3D force. This external force term is computed from the residual of the algebraic reconstruction procedures. In the multi-modal case we replace the residual between the digitally reconstructed radiographs (DRR) and observed X-ray images with a statistical based distance measure. We integrate the algebraic reconstruction technique into a variational registration framework, so that the 3D displacement field is driven to minimize the reconstruction distance between the volumetric data and its 2D projections using mutual information (MI). The benefits of this 2D-3D registration approach are its scalability in the number of used X-ray reference images and the proposed distance that can handle low contrast fluoroscopies as well. Experimental results are presented on both artificial phantom and 3D C-arm CT images.

  2. MUTUAL INFORMATION BASED 3D NON-RIGID REGISTRATION OF CT/MR ABDOMEN IMAGES

    Institute of Scientific and Technical Information of China (English)

    HU; Hai-bo(

    2001-01-01

    [1]Maintz J B, Viergever M A. A survey of medical image registration[J]. Medical Image Analysis, 1998, 3(1):1~37.[2]Collignon A. Automated multi-modality image registration based on information theory[J]. Computational Imaging and vision, 1995, 3:263~274.[3]Eberl S, Braun M. Intra-and inter-modality registration of functional and anatomical clinical images[A]. Pham B, et al. eds. New Approaches in Medical Image Analysis, SPIE 3747[C].[s.l.]:[s.n.], 1999. 102~114.[4]Lau Y H, Braun M, Hutton B F. Non-rigid 3D image registration using regionally constrained matching and the correlation ratio[A]. Pernus F, et al.eds. Biomedical Image Registration, Proc Int Workshop[C]. Bled, Slovenia, 1999. 137~148.[5]Wells Ⅲ W M, Viola P, Atsumi H, et al. Multi-modal volume registration by maximization of mutual information[J]. Medical Image Analysis, 1996, 1(1):35~51.[6]Feldmar J, Ayache N. Rigid, affine and locally affine registration of free-form surfaces[J]. Int J of Computer Vision, 1996, 23(3):97~104.

  3. Nonrigid registration algorithm for longitudinal breast MR images and the preliminary analysis of breast tumor response

    Science.gov (United States)

    Li, Xia; Dawant, Benoit M.; Welch, E. Brian; Chakravarthy, A. Bapsi; Freehardt, Darla; Mayer, Ingrid; Kelley, Mark; Meszoely, Ingrid; Gore, John C.; Yankeelov, Thomas E.

    2009-02-01

    Although useful for the detection of breast cancers, conventional imaging methods, including mammography and ultrasonography, do not provide adequate information regarding response to therapy. Dynamic contrast enhanced MRI (DCE-MRI) has emerged as a promising technique to provide relevant information on tumor status. Consequently, accurate longitudinal registration of breast MR images is critical for the comparison of changes induced by treatment at the voxel level. In this study, a nonrigid registration algorithm is proposed to allow for longitudinal registration of breast MR images obtained throughout the course of treatment. We accomplish this by modifying the adaptive bases algorithm (ABA) through adding a tumor volume preserving constraint in the cost function. The registration results demonstrate the proposed algorithm can successfully register the longitudinal breast MR images and permit analysis of the parameter maps. We also propose a novel validation method to evaluate the proposed registration algorithm quantitatively. These validations also demonstrate that the proposed algorithm constrains tumor deformation well and performs better than the unconstrained ABA algorithm.

  4. Fuzzy B-Spline Surface Modeling

    Directory of Open Access Journals (Sweden)

    Rozaimi Zakaria

    2014-01-01

    Full Text Available This paper discusses the construction of a fuzzy B-spline surface model. The construction of this model is based on fuzzy set theory which is based on fuzzy number and fuzzy relation concepts. The proposed theories and concepts define the uncertainty data sets which represent fuzzy data/control points allowing the uncertainties data points modeling which can be visualized and analyzed. The fuzzification and defuzzification processes were also defined in detail in order to obtain the fuzzy B-spline surface crisp model. Final section shows an application of fuzzy B-spline surface modeling for terrain modeling which shows its usability in handling uncertain data.

  5. A novel flexible framework with automatic feature correspondence optimization for nonrigid registration in radiotherapy.

    Science.gov (United States)

    Vásquez Osorio, Eliana M; Hoogeman, Mischa S; Bondar, Luiza; Levendag, Peter C; Heijmen, Ben J M

    2009-07-01

    Technical improvements in planning and dose delivery and in verification of patient positioning have substantially widened the therapeutic window for radiation treatment of cancer. However, changes in patient anatomy during the treatment limit the exploitation of these new techniques. To further improve radiation treatments, anatomical changes need to be modeled and accounted for Nonrigid registration can be used for this purpose. This article describes the design, the implementation, and the validation of a new framework for nonrigid registration for radiotherapy applications. The core of this framework is an improved version of the thin plate spline robust point matching (TPS-RPM) algorithm. The TPS-RPM algorithm estimates a global correspondence and a transformation between the points that represent organs of interest belonging to two image sets. However, the algorithm does not allow for the inclusion of prior knowledge on the correspondence of subset of points, and therefore, it can lead to inconsistent anatomical solutions. In this article TPS-RPM was improved by employing a novel correspondence filter that supports simultaneous registration of multiple structures. The improved method allows for coherent organ registration and for the inclusion of user-defined landmarks, lines, and surfaces inside and outside of structures of interest. A procedure to generate control points from segmented organs is described. The framework parameters r and lambda, which control the number of points and the nonrigidness of the transformation, respectively, were optimized for three sites with different degrees of deformation (head and neck, prostate, and cervix) using two cases per site. For the head and neck cases, the salivary glands were manually contoured on CT scans, for the prostate cases the prostate and the vesicles, and for the cervix cases the cervix uterus, the bladder, and the rectum. The transformation error obtained using the best set of parameters was below 1 mm

  6. A novel flexible framework with automatic feature correspondence optimization for nonrigid registration in radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Vasquez Osorio, Eliana M.; Hoogeman, Mischa S.; Bondar, Luiza; Levendag, Peter C.; Heijmen, Ben J. M. [Department of Radiation Oncology, Daniel den Hoed Cancer Center, Erasmus Medical Center, Rotterdam 3075 (Netherlands)

    2009-07-15

    Technical improvements in planning and dose delivery and in verification of patient positioning have substantially widened the therapeutic window for radiation treatment of cancer. However, changes in patient anatomy during the treatment limit the exploitation of these new techniques. To further improve radiation treatments, anatomical changes need to be modeled and accounted for. Nonrigid registration can be used for this purpose. This article describes the design, the implementation, and the validation of a new framework for nonrigid registration for radiotherapy applications. The core of this framework is an improved version of the thin plate spline robust point matching (TPS-RPM) algorithm. The TPS-RPM algorithm estimates a global correspondence and a transformation between the points that represent organs of interest belonging to two image sets. However, the algorithm does not allow for the inclusion of prior knowledge on the correspondence of subset of points, and therefore, it can lead to inconsistent anatomical solutions. In this article TPS-RPM was improved by employing a novel correspondence filter that supports simultaneous registration of multiple structures. The improved method allows for coherent organ registration and for the inclusion of user-defined landmarks, lines, and surfaces inside and outside of structures of interest. A procedure to generate control points from segmented organs is described. The framework parameters r and {lambda}, which control the number of points and the nonrigidness of the transformation, respectively, were optimized for three sites with different degrees of deformation (head and neck, prostate, and cervix) using two cases per site. For the head and neck cases, the salivary glands were manually contoured on CT scans, for the prostate cases the prostate and the vesicles, and for the cervix cases the cervix uterus, the bladder, and the rectum. The transformation error obtained using the best set of parameters was below 1

  7. Non-Rigid Registration of Liver CT Images for CT-Guided Ablation of Liver Tumors.

    Science.gov (United States)

    Luu, Ha Manh; Klink, Camiel; Niessen, Wiro; Moelker, Adriaan; Walsum, Theo van

    2016-01-01

    CT-guided percutaneous ablation for liver cancer treatment is a relevant technique for patients not eligible for surgery and with tumors that are inconspicuous on US imaging. The lack of real-time imaging and the use of a limited amount of CT contrast agent make targeting the tumor with the needle challenging. In this study, we evaluate a registration framework that allows the integration of diagnostic pre-operative contrast enhanced CT images and intra-operative non-contrast enhanced CT images to improve image guidance in the intervention. The liver and tumor are segmented in the pre-operative contrast enhanced CT images. Next, the contrast enhanced image is registered to the intra-operative CT images in a two-stage approach. First, the contrast-enhanced diagnostic image is non-rigidly registered to a non-contrast enhanced image that is conventionally acquired at the start of the intervention. In case the initial registration is not sufficiently accurate, a refinement step is applied using non-rigid registration method with a local rigidity term. In the second stage, the intra-operative CT-images that are used to check the needle position, which often consist of only a few slices, are registered rigidly to the intra-operative image that was acquired at the start of the intervention. Subsequently, the diagnostic image is registered to the current intra-operative image, using both transformations, this allows the visualization of the tumor region extracted from pre-operative data in the intra-operative CT images containing needle. The method is evaluated on imaging data of 19 patients at the Erasmus MC. Quantitative evaluation is performed using the Dice metric, mean surface distance of the liver border and corresponding landmarks in the diagnostic and the intra-operative images. The registration of the diagnostic CT image to the initial intra-operative CT image did not require a refinement step in 13 cases. For those cases, the resulting registration had a Dice

  8. Comparing nonrigid registration techniques for motion corrected MR prostate diffusion imaging

    Energy Technology Data Exchange (ETDEWEB)

    Buerger, C., E-mail: christian.buerger@philips.com; Sénégas, J.; Kabus, S.; Carolus, H.; Schulz, H.; Renisch, S. [Philips Research Hamburg, Hamburg 22335 (Germany); Agarwal, H. [Philips Research North America, Briarcliff Manor, New York 10510 and Molecular Imaging Program, NCI, National Institute of Health, Bethesda, Maryland 20892 (United States); Turkbey, B.; Choyke, P. L. [Molecular Imaging Program, NCI, National Institute of Health, Bethesda, Maryland 20892 (United States)

    2015-01-15

    Purpose: T{sub 2}-weighted magnetic resonance imaging (MRI) is commonly used for anatomical visualization in the pelvis area, such as the prostate, with high soft-tissue contrast. MRI can also provide functional information such as diffusion-weighted imaging (DWI) which depicts the molecular diffusion processes in biological tissues. The combination of anatomical and functional imaging techniques is widely used in oncology, e.g., for prostate cancer diagnosis and staging. However, acquisition-specific distortions as well as physiological motion lead to misalignments between T{sub 2} and DWI and consequently to a reduced diagnostic value. Image registration algorithms are commonly employed to correct for such misalignment. Methods: The authors compare the performance of five state-of-the-art nonrigid image registration techniques for accurate image fusion of DWI with T{sub 2}. Results: Image data of 20 prostate patients with cancerous lesions or cysts were acquired. All registration algorithms were validated using intensity-based as well as landmark-based techniques. Conclusions: The authors’ results show that the “fast elastic image registration” provides most accurate results with a target registration error of 1.07 ± 0.41 mm at minimum execution times of 11 ± 1 s.

  9. Effects of Reusing Baseline Volumes of Interest by Applying (Non-)Rigid Image Registration on Positron Emission Tomography Response Assessments

    OpenAIRE

    van Velden, Floris H. P.; Ida A Nissen; Wendy Hayes; Velasquez, Linda M; Hoekstra, Otto S.; Ronald Boellaard

    2014-01-01

    OBJECTIVES: Reusing baseline volumes of interest (VOI) by applying non-rigid and to some extent (local) rigid image registration showed good test-retest variability similar to delineating VOI on both scans individually. The aim of the present study was to compare response assessments and classifications based on various types of image registration with those based on (semi)-automatic tumour delineation. METHODS: Baseline (n = 13), early (n = 12) and late (n = 9) response (after one and three ...

  10. Validation of non-rigid point-set registration methods using a porcine bladder pelvic phantom.

    Science.gov (United States)

    Zakariaee, Roja; Hamarneh, Ghassan; Brown, Colin J; Spadinger, Ingrid

    2016-01-21

    The problem of accurate dose accumulation in fractionated radiotherapy treatment for highly deformable organs, such as bladder, has garnered increasing interest over the past few years. However, more research is required in order to find a robust and efficient solution and to increase the accuracy over the current methods. The purpose of this study was to evaluate the feasibility and accuracy of utilizing non-rigid (affine or deformable) point-set registration in accumulating dose in bladder of different sizes and shapes. A pelvic phantom was built to house an ex vivo porcine bladder with fiducial landmarks adhered onto its surface. Four different volume fillings of the bladder were used (90, 180, 360 and 480 cc). The performance of MATLAB implementations of five different methods were compared, in aligning the bladder contour point-sets. The approaches evaluated were coherent point drift (CPD), gaussian mixture model, shape context, thin-plate spline robust point matching (TPS-RPM) and finite iterative closest point (ICP-finite). The evaluation metrics included registration runtime, target registration error (TRE), root-mean-square error (RMS) and Hausdorff distance (HD). The reference (source) dataset was alternated through all four points-sets, in order to study the effect of reference volume on the registration outcomes. While all deformable algorithms provided reasonable registration results, CPD provided the best TRE values (6.4 mm), and TPS-RPM yielded the best mean RMS and HD values (1.4 and 6.8 mm, respectively). ICP-finite was the fastest technique and TPS-RPM, the slowest. PMID:26740511

  11. Uniform trigonometric polynomial B-spline curves

    Institute of Scientific and Technical Information of China (English)

    吕勇刚; 汪国昭; 杨勋年

    2002-01-01

    This paper presents a new kind of uniform spline curve, named trigonometric polynomialB-splines, over space Ω = span{sint, cost, tk-3,tk-4,…,t,1} of which k is an arbitrary integerlarger than or equal to 3. We show that trigonometric polynomial B-spline curves have many similarV properties to traditional B-splines. Based on the explicit representation of the curve we have also presented the subdivision formulae for this new kind of curve. Since the new spline can include both polynomial curves and trigonometric curves as special cases without rational form, it can be used as an efficient new model for geometric design in the fields of CAD/CAM.

  12. Lung segmentation in chest radiographs using anatomical atlases with nonrigid registration.

    Science.gov (United States)

    Candemir, Sema; Jaeger, Stefan; Palaniappan, Kannappan; Musco, Jonathan P; Singh, Rahul K; Zhiyun Xue; Karargyris, Alexandros; Antani, Sameer; Thoma, George; McDonald, Clement J

    2014-02-01

    The National Library of Medicine (NLM) is developing a digital chest X-ray (CXR) screening system for deployment in resource constrained communities and developing countries worldwide with a focus on early detection of tuberculosis. A critical component in the computer-aided diagnosis of digital CXRs is the automatic detection of the lung regions. In this paper, we present a nonrigid registration-driven robust lung segmentation method using image retrieval-based patient specific adaptive lung models that detects lung boundaries, surpassing state-of-the-art performance. The method consists of three main stages: 1) a content-based image retrieval approach for identifying training images (with masks) most similar to the patient CXR using a partial Radon transform and Bhattacharyya shape similarity measure, 2) creating the initial patient-specific anatomical model of lung shape using SIFT-flow for deformable registration of training masks to the patient CXR, and 3) extracting refined lung boundaries using a graph cuts optimization approach with a customized energy function. Our average accuracy of 95.4% on the public JSRT database is the highest among published results. A similar degree of accuracy of 94.1% and 91.7% on two new CXR datasets from Montgomery County, MD, USA, and India, respectively, demonstrates the robustness of our lung segmentation approach. PMID:24239990

  13. Topology preserving non-rigid image registration using time-varying elasticity model for MRI brain volumes.

    Science.gov (United States)

    Ahmad, Sahar; Khan, Muhammad Faisal

    2015-12-01

    In this paper, we present a new non-rigid image registration method that imposes a topology preservation constraint on the deformation. We propose to incorporate the time varying elasticity model into the deformable image matching procedure and constrain the Jacobian determinant of the transformation over the entire image domain. The motion of elastic bodies is governed by a hyperbolic partial differential equation, generally termed as elastodynamics wave equation, which we propose to use as a deformation model. We carried out clinical image registration experiments on 3D magnetic resonance brain scans from IBSR database. The results of the proposed registration approach in terms of Kappa index and relative overlap computed over the subcortical structures were compared against the existing topology preserving non-rigid image registration methods and non topology preserving variant of our proposed registration scheme. The Jacobian determinant maps obtained with our proposed registration method were qualitatively and quantitatively analyzed. The results demonstrated that the proposed scheme provides good registration accuracy with smooth transformations, thereby guaranteeing the preservation of topology.

  14. Incorporation of Preprocedural PET into CT-Guided Radiofrequency Ablation of Hepatic Metastases: a Nonrigid Image Registration Validation Study

    OpenAIRE

    Lei, Peng; Dandekar, Omkar; Widlus, David; Shekhar, Raj

    2009-01-01

    This study evaluates the accuracy of augmenting initial intraprocedural computed tomography (CT) during radiofrequency ablation (RFA) of hepatic metastases with preprocedural positron emission tomography (PET) through a hardware-accelerated implementation of an automatic nonrigid PET–CT registration algorithm. The feasibility of augmenting intraprocedural CT with preprocedural PET to improve localization of CT-invisible but PET-positive tumors with images from actual RFA was explored. Preproc...

  15. Quadrotor system identification using the multivariate multiplex b-spline

    NARCIS (Netherlands)

    Visser, T.; De Visser, C.C.; Van Kampen, E.J.

    2015-01-01

    A novel method for aircraft system identification is presented that is based on a new multivariate spline type; the multivariate multiplex B-spline. The multivariate multiplex B-spline is a generalization of the recently introduced tensor-simplex B-spline. Multivariate multiplex splines obtain simil

  16. DIRECT MANIPULATION OF B-SPLINE SURFACES

    Institute of Scientific and Technical Information of China (English)

    Wang Zhiguo; Zhou Laishui; Wang Xiaoping

    2005-01-01

    Engineering design and geometric modeling often require the ability to modify the shape of parametric curves and surfaces so that their shape satisfy some given geometric constraints, including point, normal vector, curve and surface. Two approaches are presented to directly manipulate the shape of B-spline surface. The former is based on the least-square, whereas the latter is based on minimizing the bending energy of surface. For each method, since unified and explicit formulae are derived to compute new control points of modified surface, these methods are simple, fast and applicable for CAD systems. Algebraic technique is used to simplify the computation of B-spline composition and multiplication. Comparisons and examples are also given.

  17. A Bayesian nonrigid registration method to enhance intraoperative target definition in image-guided prostate procedures through uncertainty characterization

    Energy Technology Data Exchange (ETDEWEB)

    Pursley, Jennifer; Risholm, Petter; Fedorov, Andriy; Tuncali, Kemal; Fennessy, Fiona M.; Wells, William M. III; Tempany, Clare M.; Cormack, Robert A. [Department of Radiation Oncology, Brigham and Women' s Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115 (United States); Department of Radiology, Brigham and Women' s Hospital, Harvard Medical School, Boston, Massachusetts 02115 (United States); Department of Radiation Oncology, Brigham and Women' s Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115 (United States)

    2012-11-15

    Purpose: This study introduces a probabilistic nonrigid registration method for use in image-guided prostate brachytherapy. Intraoperative imaging for prostate procedures, usually transrectal ultrasound (TRUS), is typically inferior to diagnostic-quality imaging of the pelvis such as endorectal magnetic resonance imaging (MRI). MR images contain superior detail of the prostate boundaries and provide substructure features not otherwise visible. Previous efforts to register diagnostic prostate images with the intraoperative coordinate system have been deterministic and did not offer a measure of the registration uncertainty. The authors developed a Bayesian registration method to estimate the posterior distribution on deformations and provide a case-specific measure of the associated registration uncertainty. Methods: The authors adapted a biomechanical-based probabilistic nonrigid method to register diagnostic to intraoperative images by aligning a physician's segmentations of the prostate in the two images. The posterior distribution was characterized with a Markov Chain Monte Carlo method; the maximum a posteriori deformation and the associated uncertainty were estimated from the collection of deformation samples drawn from the posterior distribution. The authors validated the registration method using a dataset created from ten patients with MRI-guided prostate biopsies who had both diagnostic and intraprocedural 3 Tesla MRI scans. The accuracy and precision of the estimated posterior distribution on deformations were evaluated from two predictive distance distributions: between the deformed central zone-peripheral zone (CZ-PZ) interface and the physician-labeled interface, and based on physician-defined landmarks. Geometric margins on the registration of the prostate's peripheral zone were determined from the posterior predictive distance to the CZ-PZ interface separately for the base, mid-gland, and apical regions of the prostate. Results: The authors

  18. A Bayesian nonrigid registration method to enhance intraoperative target definition in image-guided prostate procedures through uncertainty characterization

    International Nuclear Information System (INIS)

    Purpose: This study introduces a probabilistic nonrigid registration method for use in image-guided prostate brachytherapy. Intraoperative imaging for prostate procedures, usually transrectal ultrasound (TRUS), is typically inferior to diagnostic-quality imaging of the pelvis such as endorectal magnetic resonance imaging (MRI). MR images contain superior detail of the prostate boundaries and provide substructure features not otherwise visible. Previous efforts to register diagnostic prostate images with the intraoperative coordinate system have been deterministic and did not offer a measure of the registration uncertainty. The authors developed a Bayesian registration method to estimate the posterior distribution on deformations and provide a case-specific measure of the associated registration uncertainty. Methods: The authors adapted a biomechanical-based probabilistic nonrigid method to register diagnostic to intraoperative images by aligning a physician's segmentations of the prostate in the two images. The posterior distribution was characterized with a Markov Chain Monte Carlo method; the maximum a posteriori deformation and the associated uncertainty were estimated from the collection of deformation samples drawn from the posterior distribution. The authors validated the registration method using a dataset created from ten patients with MRI-guided prostate biopsies who had both diagnostic and intraprocedural 3 Tesla MRI scans. The accuracy and precision of the estimated posterior distribution on deformations were evaluated from two predictive distance distributions: between the deformed central zone-peripheral zone (CZ-PZ) interface and the physician-labeled interface, and based on physician-defined landmarks. Geometric margins on the registration of the prostate's peripheral zone were determined from the posterior predictive distance to the CZ-PZ interface separately for the base, mid-gland, and apical regions of the prostate. Results: The authors observed

  19. Scalable low-complexity B-spline discretewavelet transform architecture

    OpenAIRE

    Martina, Maurizio; Masera, Guido; Piccinini, Gianluca

    2010-01-01

    A scalable discrete wavelet transform architecture based on the B-spline factorisation is presented. In particular, it is shown that several wavelet filters of practical interest have a common structure in the distributed part of their B-spline factorisation. This common structure is effectively exploited to achieve scalability and to save multipliers compared with a direct polyphase B-spline implementation. Since the proposed solution is more robust to coefficient quantisation than direct po...

  20. Non-rigid contour-to-pixel registration of photographic and quantitative light-induced fluorescence imaging of decalcified teeth

    Science.gov (United States)

    Berkels, Benjamin; Deserno, Thomas; Ehrlich, Eva E.; Fritz, Ulrike B.; Sirazitdinova, Ekaterina; Tatano, Rosalia

    2016-03-01

    Quantitative light-induced fluorescence (QLF) is widely used to assess the damage of a tooth due to decalcification. In digital photographs, decalcification appears as white spot lesions, i.e. white spots on the tooth surface. We propose a novel multimodal registration approach for the matching of digital photographs and QLF images of decalcified teeth. The registration is based on the idea of contour-to-pixel matching. Here, the curve, which represents the shape of the tooth, is extracted from the QLF image using a contour segmentation by binarization and morphological processing. This curve is aligned to the photo with a non-rigid variational registration approach. Thus, the registration problem is formulated as minimization problem with an objective function that consists of a data term and a regularizer for the deformation. To construct the data term, the photo is pointwise classified into tooth and non-tooth regions. Then, the signed distance function of the tooth region allows to measure the mismatch between curve and photo. As regularizer a higher order, linear elastic prior is used. The resulting minimization problem is solved numerically using bilinear Finite Elements for the spatial discretization and the Gauss-Newton algorithm. The evaluation is based on 150 image pairs, where an average of 5 teeth have been captured from 32 subjects. All registrations have been confirmed correctly by a dental expert. The contour-to-pixel methods can directly be used in 3D for surface-to-voxel tasks.

  1. Faired MISO B-Spline Fuzzy Systems and Its Applications

    Directory of Open Access Journals (Sweden)

    Tan Yanhua

    2013-01-01

    Full Text Available We construct two classes of faired MISO B-spline fuzzy systems using the fairing method in computer-aided geometric design (CAGD for reducing adverse effects of the inexact data. Towards this goal, we generalize the faring method to high-dimension cases so that the faring method only for SISO and DISO B-spline fuzzy systems is extended to fair the MISO ones. Then the problem to construct a faired MISO B-spline fuzzy systems is transformed into solving an optimization problem with a strictly convex quadratic objective function and the unique optimal solution vector is taken as linear combination coefficients of the basis functions for a certain B-spline fuzzy system to obtain a faired MISO B-spline fuzzy system. Furthermore, we design variable universe adaptive fuzzy controllers by B-spline fuzzy systems and faired B-spline fuzzy systems to stabilize the double inverted pendulum. The simulation results show that the controllers by faired B-spline fuzzy systems perform better than those by B-spline fuzzy systems, especially when the data for fuzzy systems are inexact.

  2. On the usefulness of gradient information in multi-objective deformable image registration using a B-spline-based dual-dynamic transformation model: comparison of three optimization algorithms

    NARCIS (Netherlands)

    Pirpinia, K.; Bosman, P.A.N.; Sonke, J.-J.; van Herk, M.; Alderliesten, T.

    2015-01-01

    The use of gradient information is well-known to be highly useful in single-objective optimization-based image registration methods. However, its usefulness has not yet been investigated for deformable image registration from a multi-objective optimization perspective. To this end, within a previous

  3. Exponential B-splines and the partition of unity property

    DEFF Research Database (Denmark)

    Christensen, Ole; Massopust, Peter

    2012-01-01

    We provide an explicit formula for a large class of exponential B-splines. Also, we characterize the cases where the integer-translates of an exponential B-spline form a partition of unity up to a multiplicative constant. As an application of this result we construct explicitly given pairs of dual...

  4. Trigonometric polynomial B-spline with shape parameter

    Institute of Scientific and Technical Information of China (English)

    WANG Wentao; WANG Guozhao

    2004-01-01

    The basis function of n order trigonometric polynomial B-spline with shape parameter is constructed by an integral approach. The shape of the constructed curve can be adjusted by changing the shape parameter and it has most of the properties of B-spline. The ellipse and circle can be accurately represented by this basis function.

  5. An Intrinsic Geometric Framework for Simultaneous Non-Rigid Registration and Segmentation of Surfaces

    OpenAIRE

    Lord, Nicholas; Ho, Jeffrey; Vemuri, Baba; Eisenschenk, Stephan

    2006-01-01

    International audience In clinical applications where structural asymmetries between homologous shapes have been correlated with pathology, the questions of definition and quantification of 'asymmetry' arise naturally. When not only the degree but the position of deformity is thought relevant, asymmetry localization must also be addressed. Asymmetries between paired shapes can and have been formulated in the literature in terms of (nonrigid) diffeomorphisms between the shapes. For the infi...

  6. A note on linear B-spline copulas

    OpenAIRE

    Erdely, Arturo

    2016-01-01

    In this brief note we prove that linear B-spline copulas is not a new family of copulas since they are equivalent to checkerboard copulas, and discuss in particular how they are used to extend empirical subcopulas to copulas.

  7. Knot Insertion Algorithms for ECT B-spline Curves

    Institute of Scientific and Technical Information of China (English)

    SONG Huan-huan; TANG Yue-hong; LI Yu-juan

    2013-01-01

    Knot insertion algorithm is one of the most important technologies of B-spline method. By inserting a knot the local prop-erties of B-spline curve and the control flexibility of its shape can be further improved, also the segmentation of the curve can be re-alized. ECT spline curve is drew by the multi-knots spline curve with associated matrix in ECT spline space;Muehlbach G and Tang Y and many others have deduced the existence and uniqueness of the ECT spline function and developed many of its important properties .This paper mainly focuses on the knot insertion algorithm of ECT B-spline curve.It is the widest popularization of B-spline Behm algorithm and theory. Inspired by the Behm algorithm, in the ECT spline space, structure of generalized Pólya poly-nomials and generalized de Boor Fix dual functional, expressing new control points which are inserted after the knot by linear com-bination of original control vertex the single knot, and there are two cases, one is the single knot, the other is the double knot. Then finally comes the insertion algorithm of ECT spline curve knot. By application of the knot insertion algorithm, this paper also gives out the knot insertion algorithm of four order geometric continuous piecewise polynomial B-spline and algebraic trigonometric spline B-spline, which is consistent with previous results.

  8. Spatial shrinkage/expansion patterns between breast density measured in two MRI scans evaluated by non-rigid registration

    Energy Technology Data Exchange (ETDEWEB)

    Lin Muqing; Chen, Jeon-Hor; Bahri, Shadfar; Nalcioglu, Orhan; Su Minying [Tu and Yuen Center for Functional Onco-Imaging, Department of Radiological Sciences, University of California, Irvine, CA (United States); Mehta, Rita S [Department of Medicine, University of California, Irvine, CA (United States); Chan Siwa, E-mail: msu@uci.edu [Department of Radiology, Taichung Veterans General Hospital, Taichung, Taiwan (China)

    2011-09-21

    Breast MRI acquires many images from the breast, and computer-aided algorithms and display tools are often used to assist the radiologist's interpretation. Women with lifetime risk greater than 20% of developing breast cancer are recommended to receive annual screening MRI, but the current breast MRI computer-aided-diagnosis systems do not provide the necessary function for comparison of images acquired at different times. The purpose of this work was to develop registration methods for evaluating the spatial change pattern of fibroglandular tissue between two breast MRI scans of the same woman taken at different times. The registration method is based on rigid alignment followed by a non-rigid Demons algorithm. The method was tested on three different subjects who had different degrees of changes in the fibroglandular tissue, including two patients who showed different spatial shrinkage patterns after receiving neoadjuvant chemotherapy before surgery, and one control case from a normal volunteer. Based on the transformation matrix, the collapse of multiple voxels on the baseline images to one voxel on the follow-up images is used to calculate the shrinkage factor. Conversely, based on the reverse transformation matrix the expansion factor can be calculated. The shrinkage/expansion factor, the deformation magnitude and direction, as well as the Jacobian determinate at each location can be displayed in a 3D rendering view to show the spatial changes between two MRI scans. These different parameters show consistent results and can be used for quantitative evaluation of the spatial change patterns. The presented registration method can be further developed into a clinical tool for evaluating therapy-induced changes and for early diagnosis of breast cancer in screening MRI.

  9. Validation of TMJ osteoarthritis synthetic defect database via non-rigid registration

    Science.gov (United States)

    Paniagua, Beatriz; Pera, Juliette; Budin, Francois; Gomes, Liliane; Styner, Martin; Lucia, Cevidanes; Nguyen, Tung

    2015-03-01

    Temporomandibular joint (TMJ) disorders are a group of conditions that cause pain and dysfunction in the jaw joint and the muscles controlling jaw movement. However, diagnosis and treatment of these conditions remain controversial. To date, there is no single sign, symptom, or test that can clearly diagnose early stages of osteoarthritis (OA). Instead, the diagnosis is based on a consideration of several factors, including radiological evaluation. The current radiological diagnosis scores of TMJ pathology are subject to misdiagnosis. We believe these scores are limited by the acquisition procedures, such as oblique cuts of the CT and head positioning errors, and can lead to incorrect diagnoses of flattening of the head of the condyle, formation of osteophytes, or condylar pitting. This study consists of creating and validating a methodological framework to simulate defects in CBCT scans of known location and size, in order to create synthetic TMJ OA database. User-generated defects were created using a non-rigid deformation protocol in CBCT. All segmentation evaluation, surface distances and linear distances from the user-generated to the simulated defects showed our methodological framework to be very precise and within a voxel (0.5 mm) of magnitude. A TMJ OA synthetic database will be created next, and evaluated by expert radiologists, and this will serve to evaluate how sensitive the current radiological diagnosis tools are.

  10. Motion tracking in the liver: Validation of a method based on 4D ultrasound using a nonrigid registration technique

    Energy Technology Data Exchange (ETDEWEB)

    Vijayan, Sinara, E-mail: sinara.vijayan@ntnu.no [Norwegian University of Science and Technology, 7491 Trondheim (Norway); Klein, Stefan [Norwegian University of Science and Technology, 7491 Trondheim, Norway and Biomedical Imaging Group Rotterdam, Department of Medical Informatics and Radiology, Erasmus MC, 3000 CA Rotterdam (Netherlands); Hofstad, Erlend Fagertun; Langø, Thomas [SINTEF, Department Medical Technology, 7465 Trondheim (Norway); Lindseth, Frank [Norwegian University of Science and Technology, 7491 Trondheim, Norway and SINTEF, Department Medical Technology, 7465 Trondheim (Norway); Ystgaard, Brynjulf [Department of Surgery, St. Olavs Hospital, 7030 Trondheim (Norway)

    2014-08-15

    Purpose: Treatments like radiotherapy and focused ultrasound in the abdomen require accurate motion tracking, in order to optimize dosage delivery to the target and minimize damage to critical structures and healthy tissues around the target. 4D ultrasound is a promising modality for motion tracking during such treatments. In this study, the authors evaluate the accuracy of motion tracking in the liver based on deformable registration of 4D ultrasound images. Methods: The offline analysis was performed using a nonrigid registration algorithm that was specifically designed for motion estimation from dynamic imaging data. The method registers the entire 4D image data sequence in a groupwise optimization fashion, thus avoiding a bias toward a specifically chosen reference time point. Three healthy volunteers were scanned over several breathing cycles (12 s) from three different positions and angles on the abdomen; a total of nine 4D scans for the three volunteers. Well-defined anatomic landmarks were manually annotated in all 96 time frames for assessment of the automatic algorithm. The error of the automatic motion estimation method was compared with interobserver variability. The authors also performed experiments to investigate the influence of parameters defining the deformation field flexibility and evaluated how well the method performed with a lower temporal resolution in order to establish the minimum frame rate required for accurate motion estimation. Results: The registration method estimated liver motion with an error of 1 mm (75% percentile over all datasets), which was lower than the interobserver variability of 1.4 mm. The results were only slightly dependent on the degrees of freedom of the deformation model. The registration error increased to 2.8 mm with an eight times lower temporal resolution. Conclusions: The authors conclude that the methodology was able to accurately track the motion of the liver in the 4D ultrasound data. The authors believe

  11. Accurate recovery of 4D left ventricular deformations using volumetric B-splines incorporating phase based displacement estimates

    Science.gov (United States)

    Chen, Jian; Tustison, Nicholas J.; Amini, Amir A.

    2006-03-01

    In this paper, an improved framework for estimation of 3-D left-ventricular deformations from tagged MRI is presented. Contiguous short- and long-axis tagged MR images are collected and are used within a 4-D B-Spline based deformable model to determine 4-D displacements and strains. An initial 4-D B-spline model fitted to sparse tag line data is first constructed by minimizing a 4-D Chamfer distance potential-based energy function for aligning isoparametric planes of the model with tag line locations; subsequently, dense virtual tag lines based on 2-D phase-based displacement estimates and the initial model are created. A final 4-D B-spline model with increased knots is fitted to the virtual tag lines. From the final model, we can extract accurate 3-D myocardial deformation fields and corresponding strain maps which are local measures of non-rigid deformation. Lagrangian strains in simulated data are derived which show improvement over our previous work. The method is also applied to 3-D tagged MRI data collected in a canine.

  12. Fingerprint Representation Methods Based on B-Spline Functions

    Institute of Scientific and Technical Information of China (English)

    Ruan Ke; Xia De-lin; Yan Pu-liu

    2004-01-01

    The global characteristics of a fingerprint image such as the ridge shape and ridge topology are often ignored in most automatic fingerprint verification system. In this paper, a new representative method based on B-Spline curve is proposed to address this problem. The resultant B-Spline curves can represent the global characteristics completely and the curves are analyzable and precise. An algorithm is also proposed to extract the curves from the fingerprint image. In addition to preserve the most information of the fingerprint image, the knot-points number of the B-Spline curve is reduced to minimum in this algorithm. At the same time, the influence of the fingerprint image noise is discussed. In the end, an example is given to demonstrate the effectiveness of the representation method.

  13. SU-E-J-209: Verification of 3D Surface Registration Between Stereograms and CT Images

    Energy Technology Data Exchange (ETDEWEB)

    Han, T; Gifford, K [UT MD Anderson Cancer Center, Houston, TX (United States); Smith, B [MD Anderson Cancer Center, Houston, TX (United States); Salehpour, M [M.D. Anderson Cancer Center, Houston, TX (United States)

    2014-06-01

    Purpose: Stereography can provide a visualization of the skin surface for radiation therapy patients. The aim of this study was to verify the registration algorithm in a commercial image analysis software, 3dMDVultus, for the fusion of stereograms and CT images. Methods: CT and stereographic scans were acquired of a head phantom and a deformable phantom. CT images were imported in 3dMDVultus and the surface contours were generated by threshold segmentation. Stereograms were reconstructed in 3dMDVultus. The resulting surfaces were registered with Vultus algorithm and then exported to in-house registration software and compared with four algorithms: rigid, affine, non-rigid iterative closest point (ICP) and b-spline algorithm. RMS (root-mean-square residuals of the surface point distances) error between the registered CT and stereogram surfaces was calculated and analyzed. Results: For the head phantom, the maximum RMS error between registered CT surfaces to stereogram was 6.6 mm for Vultus algorithm, whereas the mean RMS error was 0.7 mm. For the deformable phantom, the maximum RMS error was 16.2 mm for Vultus algorithm, whereas the mean RMS error was 4.4 mm. Non-rigid ICP demonstrated the best registration accuracy, as the mean of RMS errors were both within 1 mm. Conclusion: The accuracy of registration algorithm in 3dMDVultus was verified and exceeded RMS of 2 mm for deformable cases. Non-rigid ICP and b-spline algorithms improve the registration accuracy for both phantoms, especially in deformable one. For those patients whose body habitus deforms during radiation therapy, more advanced nonrigid algorithms need to be used.

  14. Nonrigid registration-based coronary artery motion correction for cardiac computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Bhagalia, Roshni; Pack, Jed D.; Miller, James V.; Iatrou, Maria [GE Global Research, Niskayuna, New York 12309 (United States); GE Healthcare, Hoboken, New Jersey 07030 (United States)

    2012-07-15

    Purpose: X-ray computed tomography angiography (CTA) is the modality of choice to noninvasively monitor and diagnose heart disease with coronary artery health and stenosis detection being of particular interest. Reliable, clinically relevant coronary artery imaging mandates high spatiotemporal resolution. However, advances in intrinsic scanner spatial resolution (CT scanners are available which combine nearly 900 detector columns with focal spot oversampling) can be tempered by motion blurring, particularly in patients with unstable heartbeats. As a result, recently numerous methods have been devised to improve coronary CTA imaging. Solutions involving hardware, multisector algorithms, or {beta}-blockers are limited by cost, oversimplifying assumptions about cardiac motion, and populations showing contraindications to drugs, respectively. This work introduces an inexpensive algorithmic solution that retrospectively improves the temporal resolution of coronary CTA without significantly affecting spatial resolution. Methods: Given the goal of ruling out coronary stenosis, the method focuses on 'deblurring' the coronary arteries. The approach makes no assumptions about cardiac motion, can be used on exams acquired at high heart rates (even over 75 beats/min), and draws on a fast and accurate three-dimensional (3D) nonrigid bidirectional labeled point matching approach to estimate the trajectories of the coronary arteries during image acquisition. Motion compensation is achieved by employing a 3D warping of a series of partial reconstructions based on the estimated motion fields. Each of these partial reconstructions is created from data acquired over a short time interval. For brevity, the algorithm 'Subphasic Warp and Add' (SWA) reconstruction. Results: The performance of the new motion estimation-compensation approach was evaluated by a systematic observer study conducted using nine human cardiac CTA exams acquired over a range of average heart

  15. Non-rigid registration of a 3D ultrasound and a MR image data set of the female pelvic floor using a biomechanical model

    Directory of Open Access Journals (Sweden)

    Rexilius Jan

    2005-03-01

    Full Text Available Abstract Background The visual combination of different modalities is essential for many medical imaging applications in the field of Computer-Assisted medical Diagnosis (CAD to enhance the clinical information content. Clinically, incontinence is a diagnosis with high clinical prevalence and morbidity rate. The search for a method to identify risk patients and to control the success of operations is still a challenging task. The conjunction of magnetic resonance (MR and 3D ultrasound (US image data sets could lead to a new clinical visual representation of the morphology as we show with corresponding data sets of the female anal canal with this paper. Methods We present a feasibility study for a non-rigid registration technique based on a biomechanical model for MR and US image data sets of the female anal canal as a base for a new innovative clinical visual representation. Results It is shown in this case study that the internal and external sphincter region could be registered elastically and the registration partially corrects the compression induced by the ultrasound transducer, so the MR data set showing the native anatomy is used as a frame for the US data set showing the same region with higher resolution but distorted by the transducer Conclusion The morphology is of special interest in the assessment of anal incontinence and the non-rigid registration of normal clinical MR and US image data sets is a new field of the adaptation of this method incorporating the advantages of both technologies.

  16. Evaluation of non-rigid constrained CT/CBCT registration algorithms for delineation propagation in the context of prostate cancer radiotherapy

    Science.gov (United States)

    Rubeaux, Mathieu; Simon, Antoine; Gnep, Khemara; Colliaux, Jérémy; Acosta, Oscar; de Crevoisier, Renaud; Haigron, Pascal

    2013-03-01

    Image-Guided Radiation Therapy (IGRT) aims at increasing the precision of radiation dose delivery. In the context of prostate cancer, a planning Computed Tomography (CT) image with manually defined prostate and organs at risk (OAR) delineations is usually associated with daily Cone Beam Computed Tomography (CBCT) follow-up images. The CBCT images allow to visualize the prostate position and to reposition the patient accordingly. They also should be used to evaluate the dose received by the organs at each fraction of the treatment. To do so, the first step is a prostate and OAR segmentation on the daily CBCTs, which is very timeconsuming. To simplify this task, CT to CBCT non-rigid registration could be used in order to propagate the original CT delineations in the CBCT images. For this aim, we compared several non-rigid registration methods. They are all based on the Mutual Information (MI) similarity measure, and use a BSpline transformation model. But we add different constraints to this global scheme in order to evaluate their impact on the final results. These algorithms are investigated on two real datasets, representing a total of 70 CBCT on which a reference delineation has been realized. The evaluation is led using the Dice Similarity Coefficient (DSC) as a quality criteria. The experiments show that a rigid penalty term on the bones improves the final registration result, providing high quality propagated delineations.

  17. Color management with a hammer: the B-spline fitter

    Science.gov (United States)

    Bell, Ian E.; Liu, Bonny H. P.

    2003-01-01

    To paraphrase Abraham Maslow: If the only tool you have is a hammer, every problem looks like a nail. We have a B-spline fitter customized for 3D color data, and many problems in color management can be solved with this tool. Whereas color devices were once modeled with extensive measurement, look-up tables and trilinear interpolation, recent improvements in hardware have made B-spline models an affordable alternative. Such device characterizations require fewer color measurements than piecewise linear models, and have uses beyond simple interpolation. A B-spline fitter, for example, can act as a filter to remove noise from measurements, leaving a model with guaranteed smoothness. Inversion of the device model can then be carried out consistently and efficiently, as the spline model is well behaved and its derivatives easily computed. Spline-based algorithms also exist for gamut mapping, the composition of maps, and the extrapolation of a gamut. Trilinear interpolation---a degree-one spline---can still be used after nonlinear spline smoothing for high-speed evaluation with robust convergence. Using data from several color devices, this paper examines the use of B-splines as a generic tool for modeling devices and mapping one gamut to another, and concludes with applications to high-dimensional and spectral data.

  18. A new technique for noise reduction at coronary CT angiography with multi-phase data-averaging and non-rigid image registration

    Energy Technology Data Exchange (ETDEWEB)

    Tatsugami, Fuminari; Higaki, Toru; Nakamura, Yuko; Yamagami, Takuji; Date, Shuji; Awai, Kazuo [Hiroshima University, Department of Diagnostic Radiology, Minami-ku, Hiroshima (Japan); Fujioka, Chikako; Kiguchi, Masao [Hiroshima University, Department of Radiology, Minami-ku, Hiroshima (Japan); Kihara, Yasuki [Hiroshima University, Department of Cardiovascular Medicine, Minami-ku, Hiroshima (Japan)

    2015-01-15

    To investigate the feasibility of a newly developed noise reduction technique at coronary CT angiography (CTA) that uses multi-phase data-averaging and non-rigid image registration. Sixty-five patients underwent coronary CTA with prospective ECG-triggering. The range of the phase window was set at 70-80 % of the R-R interval. First, three sets of consecutive volume data at 70 %, 75 % and 80 % of the R-R interval were prepared. Second, we applied non-rigid registration to align the 70 % and 80 % images to the 75 % image. Finally, we performed weighted averaging of the three images and generated a de-noised image. The image noise and contrast-to-noise ratio (CNR) in the proximal coronary arteries between the conventional 75 % and the de-noised images were compared. Two radiologists evaluated the image quality using a 5-point scale (1, poor; 5, excellent). On de-noised images, mean image noise was significantly lower than on conventional 75 % images (18.3 HU ± 2.6 vs. 23.0 HU ± 3.3, P < 0.01) and the CNR was significantly higher (P < 0.01). The mean image quality score for conventional 75 % and de-noised images was 3.9 and 4.4, respectively (P < 0.01). Our method reduces image noise and improves image quality at coronary CTA. (orig.)

  19. RECONSTRUCTION OF LAYER DATA WITH DEFORMABLE B-SPLINES

    Institute of Scientific and Technical Information of China (English)

    Cheng Siyuan; Zhang Xiangwei; Xiong Hanwei

    2005-01-01

    A new B-spline surface reconstruction method from layer data based on deformable model is presented. An initial deformable surface, which is represented as a closed cylinder, is firstly given. The surface is subject to internal forces describing its implicit smoothness property and external forces attracting it toward the layer data points. And then finite element method is adopted to solve its energy minimization problem, which results a bicubic closed B-spline surface with C2 continuity. The proposed method can provide a smoothness and accurate surface model directly from the layer data, without the need to fit cross-sectional curves and make them compatible. The feasibility of the proposed method is verified by the experimental results.

  20. A B-spline active contour model based on finite element method

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A B-spline active contour model based on finite element method is presented, into which the advantages of a B-spline active contour attributing to its fewer parameters and its smoothness is built accompanied with reduced computational complexity and better numerical stability resulted from the finite element method. In this model, a cubic B-spline segment is taken as an element, and the finite element method is adopted to solve the energy minimization problem of the B-spline active contour, thus to implement image segmentation. Experiment results verify that this method is efficient for B-spline active contour, which attains stable, accurate and faster convergence.

  1. A matrix method for degree-raising of B-spline curves

    Institute of Scientific and Technical Information of China (English)

    秦开怀

    1997-01-01

    A new identity is proved that represents the kth order B-splines as linear combinations of the (k + 1) th order B-splines A new method for degree-raising of B-spline curves is presented based on the identity. The new method can be used for all kinds of B-spline curves, that is, both uniform and arbitrarily nonuniform B-spline curves. When used for degree-raising of a segment of a uniform B-spline curve of degree k - 1, it can help obtain a segment of curve of degree k that is still a uniform B-spline curve without raising the multiplicity of any knot. The method for degree-raising of Bezier curves can be regarded as the special case of the new method presented. Moreover, the conventional theory for degree-raising, whose shortcoming has been found, is discussed.

  2. 4D ultrasound and 3D MRI registration of beating heart

    International Nuclear Information System (INIS)

    To realize intra-cardiac surgery without cardio-pulmonary bypass, a medical imaging technique with both high image quality and data acquisition rate that is fast enough to follow heart beat movements is required. In this research, we proposed a method that utilized the image quality of MRI and the speed of ultrasound. We developed a 4D image reconstruction method using image registration of 3D MRI and 4D ultrasound images. The registration method consists of rigid registration between 3D MRI and 3D ultrasound with the same heart beat phase, and non-rigid registration between 3D ultrasound images from different heart beat phases. Non-rigid registration was performed with B-spline based registration using variable spring model. In phantom experiment using balloon phantom, registration accuracy was less than 2 mm for total heart volume variation range of 10%. We applied our registration method on 3D MRI and 4D ultrasound images of a volunteer's beating heart data and confirmed through visual observation that heart beat pattern was well reproduced. (orig.)

  3. Research on Non-rigid Registration in Uterine Fibroids MR Imaging%子宫肌瘤MRI影像非刚性配准研究

    Institute of Scientific and Technical Information of China (English)

    所世腾; 张良宾; 李跃华; 陈亚珠; 张素

    2012-01-01

    高强度聚焦超声(High-Intensity Focused Ultrasound,HIFU)治疗和磁共振技术结合(MRl-guided HIFU,MRgHIFU)采用MRI进行目标定位、治疗规划和能量沉积的闭环控制以保障热消融不伤及周围组织,其中图像配准是校正定位误差,实施精确治疗的重要环节.针对三维非刚性配准方法,在子宫肌瘤的治疗计划修正和跟踪方面的应用进行研究.针对前后两个不同时段采集的子宫肌瘤MR影像,分别进行基于自由形变模型(Free-From Deformation,FFD)算法和Demons算法的非刚性配准对比.实验结果表明,该基于FFD的非刚性配准算法,对于形变较小的子宫肌瘤真实数据能够取得较为合适的配准效果,重叠区域的互相关系数(CC)从配准前的0.59提高到配准后的0.74.%High-Intensity Focused Ultrasound (H1FU) combined with magnetic resonance achieves thermal ablation without hurting the surrounding tissue through a closed-loop control process of target positioning and treatment planning. Image registration is a vital important section in correction of positioning error and implement of precise treatment. Research of non-rigid registration in amendments and tracing of treatment plan was carried out, in which series of uterine fibroids MR images acquired in two different times are employed as experimental data. Then non-rigid registration based on Free-Form Deformation and Demons were performed successively for a comparison of the results. The experiments shows that the FFD based registration achieved preferable results with tiny deformation, and the correlation coefficient (CC) of overlapping region increased from 0.59 to 0.74 after registration.

  4. Hodograph computation and bound estimation for rational B-spline curves

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    It is necessary to compute the derivative and estimate the bound of rational B-spline curves in design system, which has not been studied to date. To improve the function of computer aided design (CAD) system, and to enhance the efficiency of different algorithms of rational B-spline curves, the representation of scaled hodograph and bound of derivative magnitude of uniform planar rational B-spline curves are derived by applying Dir function, which indicates the direction of Cartesian vector between homogeneous points, discrete B-spline theory and the formula of translating the product into a summation of B-spline functions. As an application of the result above,upper bound of parametric distance between any two points in a uniform planar rational B-spline curve is further presented.

  5. PCA and level set based non-rigid image registration for MRI and Paxinos-Watson atlas of rat brain

    Science.gov (United States)

    Cai, Chao; Liu, Ailing; Ding, Mingyue; Zhou, Chengping

    2007-12-01

    Image registration provides the ability to geometrically align one dataset with another. It is a basic task in a great variety of biomedical imaging applications. This paper introduced a novel three-dimensional registration method for Magnetic Resonance Image (MRI) and Paxinos-Watson Atlas of rat brain. For the purpose of adapting to a large range and non-linear deformation between MRI and atlas in higher registration accuracy, based on the segmentation of rat brain, we chose the principle components analysis (PCA) automatically performing the linear registration, and then, a level set based nonlinear registration correcting some small distortions. We implemented this registration method in a rat brain 3D reconstruction and analysis system. Experiments have demonstrated that this method can be successfully applied to registering the low resolution and noise affection MRI with Paxinos-Watson Atlas of rat brain.

  6. A fast direct point-by-point generating algorithm for B Spline curves and surfaces

    Institute of Scientific and Technical Information of China (English)

    LI Zhong; HAN Dan-fu

    2005-01-01

    Traditional generating algorithms for B Spline curves and surfaces require approximation methods where how to increment the parameter to get the best approximation is problematic; or they take the pixel-based method needing matrix transformation from B Spline representation to Bezier form. Here, a fast, direct point-by-point generating algorithm for B Spline curves and surfaces is presented. The algorithm does not need matrix transformation, can be used for uniform or nonuniform B Spline curves and surfaces of any degree, and has high generating speed and good rendering accuracy.

  7. Automatic Shape Control of Triangular B-Splines of Arbitrary Topology

    Institute of Scientific and Technical Information of China (English)

    Ying He; Xian-Feng Gu; Hong Qin

    2006-01-01

    Triangular B-splines are powerful and flexible in modeling a broader class of geometric objects defined over arbitrary, non-rectangular domains. Despite their great potential and advantages in theory, practical techniques and computational tools with triangular B-splines are less-developed. This is mainly because users have to handle a large number of irregularly distributed control points over arbitrary triangulation. In this paper, an automatic and efficient method is proposed to generate visually pleasing, high-quality triangular B-splines of arbitrary topology. The experimental results on several real datasets show that triangular B-splines are powerful and effective in both theory and practice.

  8. Impact of rigid and nonrigid registration on the determination of {sup 18}F-FDG PET-based tumour volume and standardized uptake value in patients with lung cancer

    Energy Technology Data Exchange (ETDEWEB)

    Grgic, Aleksandar; Ballek, Elena; Moca, Norbert; Schaefer, Andrea; Kirsch, Carl-Martin; Hellwig, Dirk [Saarland University Medical Center, Department of Nuclear Medicine, Homburg/Saar (Germany); Fleckenstein, Jochen; Kremp, Stephanie; Ruebe, Christian [Saarland University Medical Center, Department of Radio-Oncology, Homburg/Saar (Germany); Kuhnigk, Jan-Martin [Fraunhofer, MEVIS, Bremen (Germany)

    2011-05-15

    Assessment of the metabolically active tumour tissue by FDG PET is evolving for use in the diagnosis of non-small-cell lung cancer (NSCLC), in the planning of radiotherapy, and in follow-up and response evaluation. For exact evaluation accurate registration of PET and CT data is required. The registration process is usually based on rigid algorithms; however, nonrigid algorithms are increasingly being used. The influence of the registration method on FDG PET-based standardized uptake value (SUVmax) and metabolic tumour volume (MTV) definition has not yet been evaluated. We compared intra- and interindividual differences in SUV and MTV between rigid- and nonrigid-registered PET and CT acquired during different breathing manoeuvres. The study group comprised 28 radiotherapy candidates with histologically proven NSCLC who underwent FDG PET acquisition and three CT acquisitions (expiration - EXP, inspiration - INS, mid-breath-hold - MID). All scans were registered with both a rigid (R) and a nonrigid (NR) procedure resulting in six fused datasets: R-INS, R-EXP, R-MID, NR-INS, NR-EXP and NR-MID. For the delineation of MTVs a contrast-oriented contouring algorithm developed in-house was used. To accelerate the delineation a semiautomatic software prototype was utilized. Tumour mean SUVmax did not differ for R and NR registration (R 17.5 {+-} 7, NR 17.4 {+-} 7; p=0.2). The mean MTV was higher by 3 {+-} 12 ml (p=0.02) in the NR group than in the R group, as was the mean tumour diameter (by 0.1 {+-} 0.2 cm; p<0.01). With respect to the three different breathing manoeuvres, there were no differences in MTV in the R group (p > 0.7). In intraindividual comparison there were no significant differences in MTVs concerning the registration pairs R-EXP (68 {+-} 88 ml) vs. NR-EXP (69 {+-} 85 ml) und R-MID (68 {+-} 86 ml) vs. NR-MID (69 {+-} 83 ml) (both p > 0.4). However, the MTVs were larger after NR registration during inspiration (R-INS 68 {+-} 82 vs. NR-INS 78 {+-} 93 ml; p=0

  9. Fast Selection of Spectral Variables with B-Spline Compression

    CERN Document Server

    Rossi, Fabrice; Wertz, Vincent; Meurens, Marc; Verleysen, Michel

    2007-01-01

    The large number of spectral variables in most data sets encountered in spectral chemometrics often renders the prediction of a dependent variable uneasy. The number of variables hopefully can be reduced, by using either projection techniques or selection methods; the latter allow for the interpretation of the selected variables. Since the optimal approach of testing all possible subsets of variables with the prediction model is intractable, an incremental selection approach using a nonparametric statistics is a good option, as it avoids the computationally intensive use of the model itself. It has two drawbacks however: the number of groups of variables to test is still huge, and colinearities can make the results unstable. To overcome these limitations, this paper presents a method to select groups of spectral variables. It consists in a forward-backward procedure applied to the coefficients of a B-Spline representation of the spectra. The criterion used in the forward-backward procedure is the mutual infor...

  10. Image edges detection through B-Spline filters

    International Nuclear Information System (INIS)

    B-Spline signal processing was used to detect the edges of a digital image. This technique is based upon processing the image in the Spline transform domain, instead of doing so in the space domain (classical processing). The transformation to the Spline transform domain means finding out the real coefficients that makes it possible to interpolate the grey levels of the original image, with a B-Spline polynomial. There exist basically two methods of carrying out this interpolation, which produces the existence of two different Spline transforms: an exact interpolation of the grey values (direct Spline transform), and an approximated interpolation (smoothing Spline transform). The latter results in a higher smoothness of the gray distribution function defined by the Spline transform coefficients, and is carried out with the aim of obtaining an edge detection algorithm which higher immunity to noise. Finally the transformed image was processed in order to detect the edges of the original image (the gradient method was used), and the results of the three methods (classical, direct Spline transform and smoothing Spline transform) were compared. The results were that, as expected, the smoothing Spline transform technique produced a detection algorithm more immune to external noise. On the other hand the direct Spline transform technique, emphasizes more the edges, even more than the classical method. As far as the consuming time is concerned, the classical method is clearly the fastest one, and may be applied whenever the presence of noise is not important, and whenever edges with high detail are not required in the final image. (author). 9 refs., 17 figs., 1 tab

  11. B-spline collocation methods for numerical solutions of the Burgers' equation

    OpenAIRE

    İdris Dağ; Dursun Irk; Ali Şahin

    2005-01-01

    Both time- and space-splitted Burgers' equations are solved numerically. Cubic B-spline collocation method is applied to the time-splitted Burgers' equation. Quadratic B-spline collocation method is used to get numerical solution of the space-splitted Burgers' equation. The results of both schemes are compared for some test problems.

  12. Nonrigid motion compensation in B-mode and contrast enhanced ultrasound image sequences of the carotid artery

    Science.gov (United States)

    Carvalho, Diego D. B.; Akkus, Zeynettin; Bosch, Johan G.; van den Oord, Stijn C. H.; Niessen, Wiro J.; Klein, Stefan

    2014-03-01

    In this work, we investigate nonrigid motion compensation in simultaneously acquired (side-by-side) B-mode ultrasound (BMUS) and contrast enhanced ultrasound (CEUS) image sequences of the carotid artery. These images are acquired to study the presence of intraplaque neovascularization (IPN), which is a marker of plaque vulnerability. IPN quantification is visualized by performing the maximum intensity projection (MIP) on the CEUS image sequence over time. As carotid images contain considerable motion, accurate global nonrigid motion compensation (GNMC) is required prior to the MIP. Moreover, we demonstrate that an improved lumen and plaque differentiation can be obtained by averaging the motion compensated BMUS images over time. We propose to use a previously published 2D+t nonrigid registration method, which is based on minimization of pixel intensity variance over time, using a spatially and temporally smooth B-spline deformation model. The validation compares displacements of plaque points with manual trackings by 3 experts in 11 carotids. The average (+/- standard deviation) root mean square error (RMSE) was 99+/-74μm for longitudinal and 47+/-18μm for radial displacements. These results were comparable with the interobserver variability, and with results of a local rigid registration technique based on speckle tracking, which estimates motion in a single point, whereas our approach applies motion compensation to the entire image. In conclusion, we evaluated that the GNMC technique produces reliable results. Since this technique tracks global deformations, it can aid in the quantification of IPN and the delineation of lumen and plaque contours.

  13. Automatic generation of boundary conditions using Demons non-rigid image registration for use in 3D modality-independent elastography

    Science.gov (United States)

    Pheiffer, Thomas S.; Ou, Jao J.; Miga, Michael I.

    2010-02-01

    Modality-independent elastography (MIE) is a method of elastography that reconstructs the elastic properties of tissue using images acquired under different loading conditions and a biomechanical model. Boundary conditions are a critical input to the algorithm, and are often determined by time-consuming point correspondence methods requiring manual user input. Unfortunately, generation of accurate boundary conditions for the biomechanical model is often difficult due to the challenge of accurately matching points between the source and target surfaces and consequently necessitates the use of large numbers of fiducial markers. This study presents a novel method of automatically generating boundary conditions by non-rigidly registering two image sets with a Demons diffusion-based registration algorithm. The use of this method was successfully performed in silico using magnetic resonance and X-ray computed tomography image data with known boundary conditions. These preliminary results have produced boundary conditions with accuracy of up to 80% compared to the known conditions. Finally, these boundary conditions were utilized within a 3D MIE reconstruction to determine an elasticity contrast ratio between tumor and normal tissue. Preliminary results show a reasonable characterization of the material properties on this first attempt and a significant improvement in the automation level and viability of the method.

  14. Measurement of Strain in Cardiac Myocytes at Micrometer Scale Based on Rapid Scanning Confocal Microscopy and Non-Rigid Image Registration.

    Science.gov (United States)

    Lichter, J; Li, Hui; Sachse, Frank B

    2016-10-01

    Measurement of cell shortening is an important technique for assessment of physiology and pathophysiology of cardiac myocytes. Many types of heart disease are associated with decreased myocyte shortening, which is commonly caused by structural and functional remodeling. Here, we present a new approach for local measurement of 2-dimensional strain within cells at high spatial resolution. The approach applies non-rigid image registration to quantify local displacements and Cauchy strain in images of cells undergoing contraction. We extensively evaluated the approach using synthetic cell images and image sequences from rapid scanning confocal microscopy of fluorescently labeled isolated myocytes from the left ventricle of normal and diseased canine heart. Application of the approach yielded a comprehensive description of cellular strain including novel measurements of transverse strain and spatial heterogeneity of strain. Quantitative comparison with manual measurements of strain in image sequences indicated reliability of the developed approach. We suggest that the developed approach provides researchers with a novel tool to investigate contractility of cardiac myocytes at subcellular scale. In contrast to previously introduced methods for measuring cell shorting, the developed approach provides comprehensive information on the spatio-temporal distribution of 2-dimensional strain at micrometer scale.

  15. Micropolar Fluids Using B-spline Divergence Conforming Spaces

    KAUST Repository

    Sarmiento, Adel

    2014-06-06

    We discretized the two-dimensional linear momentum, microrotation, energy and mass conservation equations from micropolar fluids theory, with the finite element method, creating divergence conforming spaces based on B-spline basis functions to obtain pointwise divergence free solutions [8]. Weak boundary conditions were imposed using Nitsche\\'s method for tangential conditions, while normal conditions were imposed strongly. Once the exact mass conservation was provided by the divergence free formulation, we focused on evaluating the differences between micropolar fluids and conventional fluids, to show the advantages of using the micropolar fluid model to capture the features of complex fluids. A square and an arc heat driven cavities were solved as test cases. A variation of the parameters of the model, along with the variation of Rayleigh number were performed for a better understanding of the system. The divergence free formulation was used to guarantee an accurate solution of the flow. This formulation was implemented using the framework PetIGA as a basis, using its parallel stuctures to achieve high scalability. The results of the square heat driven cavity test case are in good agreement with those reported earlier.

  16. Adaptive non-uniform B-spline dictionaries on a compact interval

    CERN Document Server

    Rebollo-Neira, Laura

    2009-01-01

    Non-uniform B-spline dictionaries on a compact interval are discussed. For each given partition, dictionaries of B-spline functions for the corresponding spline space are constructed. It is asserted that, by dividing the given partition into subpartitions and joining together the bases for the concomitant subspaces, slightly redundant dictionaries of B-splines functions are obtained. Such dictionaries are proved to span the spline space associated to the given partition. The proposed construction is shown to be potentially useful for the purpose of sparse signal representation. With that goal in mind, spline spaces specially adapted to produce a sparse representation of a given signal are considered.

  17. B-SPLINE-BASED SVM MODEL AND ITS APPLICATIONS TO OIL WATER-FLOODED STATUS IDENTIFICATION

    Institute of Scientific and Technical Information of China (English)

    Shang Fuhua; Zhao Tiejun; Yi Xiongying

    2007-01-01

    A method of B-spline transform for signal feature extraction is developed. With the B-spline,the log-signal space is mapped into the vector space. An efficient algorithm based on Support Vector Machine (SVM) to automatically identify the water-flooded status of oil-saturated stratum is described.The experiments show that this algorithm can improve the performances for the identification and the generalization in the case of a limited set of samples.

  18. Numerical Method Using Cubic Trigonometric B-Spline Technique for Nonclassical Diffusion Problems

    OpenAIRE

    Muhammad Abbas; Ahmad Abd. Majid; Ahmad Izani Md Ismail; Abdur Rashid

    2014-01-01

    A new two-time level implicit technique based on cubic trigonometric B-spline is proposed for the approximate solution of a nonclassical diffusion problem with nonlocal boundary constraints. The standard finite difference approach is applied to discretize the time derivative while cubic trigonometric B-spline is utilized as an interpolating function in the space dimension. The technique is shown to be unconditionally stable using the von Neumann method. Several numerical examples are discusse...

  19. A class of compactly supported symmetric/antisymmetric B-spline wavelets

    Institute of Scientific and Technical Information of China (English)

    YANG Shouzhi; LOU Zengjian

    2005-01-01

    An algorithm for constructing a class of compactly supported symmetric/antisymmetric B-spline wavelets is presented.For any m th order and k th order cardinal B-spline Nm (x), Nk (x), if m + k is an even integer, the corresponding m th order B-spline wavelets ψkm (x) can be constructed, which are compactly supported symmetric/antisymmetric. In addition, if ψkm (x), m > 1 is m th Bspline wavelet associated with two spline functions Nm (x) and Nk (x), then (ψkm (x))′( x ) is m - 1th B-spline wavelet associated with Nm-1(x) and Nk+1(x), i.e. (ψkm(x))′(x) =22ψk+1m-1(x). Similarly, ∫x0 ψkm(t)dt, k >1 is m + 1th B-spline wavelet associated with Nm + 1 (x) and Nk-1 (x). Using this method, we recovered Chui and Wang' s spline wavelets. Since a class of B-spline wavelets are symmetric/antisymmetric, their linear phase property is assured. Several examples are also presented.

  20. B-spline active rays segmentation of microcalcifications in mammography

    Energy Technology Data Exchange (ETDEWEB)

    Arikidis, Nikolaos S.; Skiadopoulos, Spyros; Karahaliou, Anna; Likaki, Eleni; Panayiotakis, George; Costaridou, Lena [Department of Medical Physics, School of Medicine, University of Patras, 265 00 Patras (Greece); Department of Radiology, School of Medicine, University of Patras, 265 00 Patras (Greece); Department of Medical Physics, School of Medicine, University of Patras, 265 00 Patras (Greece)

    2008-11-15

    Accurate segmentation of microcalcifications in mammography is crucial for the quantification of morphologic properties by features incorporated in computer-aided diagnosis schemes. A novel segmentation method is proposed implementing active rays (polar-transformed active contours) on B-spline wavelet representation to identify microcalcification contour point estimates in a coarse-to-fine strategy at two levels of analysis. An iterative region growing method is used to delineate the final microcalcification contour curve, with pixel aggregation constrained by the microcalcification contour point estimates. A radial gradient-based method was also implemented for comparative purposes. The methods were tested on a dataset consisting of 149 mainly pleomorphic microcalcification clusters originating from 130 mammograms of the DDSM database. Segmentation accuracy of both methods was evaluated by three radiologists, based on a five-point rating scale. The radiologists' average accuracy ratings were 3.96{+-}0.77, 3.97{+-}0.80, and 3.83{+-}0.89 for the proposed method, and 2.91{+-}0.86, 2.10{+-}0.94, and 2.56{+-}0.76 for the radial gradient-based method, respectively, while the differences in accuracy ratings between the two segmentation methods were statistically significant (Wilcoxon signed-ranks test, p<0.05). The effect of the two segmentation methods in the classification of benign from malignant microcalcification clusters was also investigated. A least square minimum distance classifier was employed based on cluster features reflecting three morphological properties of individual microcalcifications (area, length, and relative contrast). Classification performance was evaluated by means of the area under ROC curve (A{sub z}). The area and length morphologic features demonstrated a statistically significant (Mann-Whitney U-test, p<0.05) higher patient-based classification performance when extracted from microcalcifications segmented by the proposed method (0

  1. BSR: B-spline atomic R-matrix codes

    Science.gov (United States)

    Zatsarinny, Oleg

    2006-02-01

    BSR is a general program to calculate atomic continuum processes using the B-spline R-matrix method, including electron-atom and electron-ion scattering, and radiative processes such as bound-bound transitions, photoionization and polarizabilities. The calculations can be performed in LS-coupling or in an intermediate-coupling scheme by including terms of the Breit-Pauli Hamiltonian. New version program summaryTitle of program: BSR Catalogue identifier: ADWY Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADWY Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Computers on which the program has been tested: Microway Beowulf cluster; Compaq Beowulf cluster; DEC Alpha workstation; DELL PC Operating systems under which the new version has been tested: UNIX, Windows XP Programming language used: FORTRAN 95 Memory required to execute with typical data: Typically 256-512 Mwords. Since all the principal dimensions are allocatable, the available memory defines the maximum complexity of the problem No. of bits in a word: 8 No. of processors used: 1 Has the code been vectorized or parallelized?: no No. of lines in distributed program, including test data, etc.: 69 943 No. of bytes in distributed program, including test data, etc.: 746 450 Peripherals used: scratch disk store; permanent disk store Distribution format: tar.gz Nature of physical problem: This program uses the R-matrix method to calculate electron-atom and electron-ion collision processes, with options to calculate radiative data, photoionization, etc. The calculations can be performed in LS-coupling or in an intermediate-coupling scheme, with options to include Breit-Pauli terms in the Hamiltonian. Method of solution: The R-matrix method is used [P.G. Burke, K.A. Berrington, Atomic and Molecular Processes: An R-Matrix Approach, IOP Publishing, Bristol, 1993; P.G. Burke, W.D. Robb, Adv. At. Mol. Phys. 11 (1975) 143; K.A. Berrington, W.B. Eissner, P.H. Norrington, Comput

  2. Non-rigid isometric ICP: A practical registration method for the analysis and compensation of form errors in production engineering

    KAUST Repository

    Sacharow, Alexei

    2011-12-01

    The unprecedented success of the iterative closest point (ICP) method for registration in geometry processing and related fields can be attributed to its efficiency, robustness, and wide spectrum of applications. Its use is however quite limited as soon as the objects to be registered arise from each other by a transformation significantly different from a Euclidean motion. We present a novel variant of ICP, tailored for the specific needs of production engineering, which registers a triangle mesh with a second surface model of arbitrary digital representation. Our method inherits most of ICP\\'s practical advantages but is capable of detecting medium-strength bendings i.e. isometric deformations. Initially, the algorithm assigns to all vertices in the source their closest point on the target mesh and then iteratively establishes isometry, a process which, very similar to ICP, requires intermediate re-projections. A NURBS-based technique for applying the resulting deformation to arbitrary instances of the source geometry, other than the very mesh used for correspondence estimation, is described before we present numerical results on synthetic and real data to underline the viability of our approach in comparison with others. © 2011 Elsevier Ltd. All rights reserved.

  3. Prostate CT segmentation method based on nonrigid registration in ultrasound-guided CT-based HDR prostate brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xiaofeng, E-mail: xyang43@emory.edu; Rossi, Peter; Ogunleye, Tomi; Marcus, David M.; Jani, Ashesh B.; Curran, Walter J.; Liu, Tian [Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, Georgia 30322 (United States); Mao, Hui [Department of Radiology and Imaging Sciences, Emory University, Atlanta, Georgia 30322 (United States)

    2014-11-01

    Purpose: The technological advances in real-time ultrasound image guidance for high-dose-rate (HDR) prostate brachytherapy have placed this treatment modality at the forefront of innovation in cancer radiotherapy. Prostate HDR treatment often involves placing the HDR catheters (needles) into the prostate gland under the transrectal ultrasound (TRUS) guidance, then generating a radiation treatment plan based on CT prostate images, and subsequently delivering high dose of radiation through these catheters. The main challenge for this HDR procedure is to accurately segment the prostate volume in the CT images for the radiation treatment planning. In this study, the authors propose a novel approach that integrates the prostate volume from 3D TRUS images into the treatment planning CT images to provide an accurate prostate delineation for prostate HDR treatment. Methods: The authors’ approach requires acquisition of 3D TRUS prostate images in the operating room right after the HDR catheters are inserted, which takes 1–3 min. These TRUS images are used to create prostate contours. The HDR catheters are reconstructed from the intraoperative TRUS and postoperative CT images, and subsequently used as landmarks for the TRUS–CT image fusion. After TRUS–CT fusion, the TRUS-based prostate volume is deformed to the CT images for treatment planning. This method was first validated with a prostate-phantom study. In addition, a pilot study of ten patients undergoing HDR prostate brachytherapy was conducted to test its clinical feasibility. The accuracy of their approach was assessed through the locations of three implanted fiducial (gold) markers, as well as T2-weighted MR prostate images of patients. Results: For the phantom study, the target registration error (TRE) of gold-markers was 0.41 ± 0.11 mm. For the ten patients, the TRE of gold markers was 1.18 ± 0.26 mm; the prostate volume difference between the authors’ approach and the MRI-based volume was 7.28% ± 0

  4. Prostate CT segmentation method based on nonrigid registration in ultrasound-guided CT-based HDR prostate brachytherapy

    Science.gov (United States)

    Yang, Xiaofeng; Rossi, Peter; Ogunleye, Tomi; Marcus, David M.; Jani, Ashesh B.; Mao, Hui; Curran, Walter J.; Liu, Tian

    2014-01-01

    Purpose: The technological advances in real-time ultrasound image guidance for high-dose-rate (HDR) prostate brachytherapy have placed this treatment modality at the forefront of innovation in cancer radiotherapy. Prostate HDR treatment often involves placing the HDR catheters (needles) into the prostate gland under the transrectal ultrasound (TRUS) guidance, then generating a radiation treatment plan based on CT prostate images, and subsequently delivering high dose of radiation through these catheters. The main challenge for this HDR procedure is to accurately segment the prostate volume in the CT images for the radiation treatment planning. In this study, the authors propose a novel approach that integrates the prostate volume from 3D TRUS images into the treatment planning CT images to provide an accurate prostate delineation for prostate HDR treatment. Methods: The authors’ approach requires acquisition of 3D TRUS prostate images in the operating room right after the HDR catheters are inserted, which takes 1–3 min. These TRUS images are used to create prostate contours. The HDR catheters are reconstructed from the intraoperative TRUS and postoperative CT images, and subsequently used as landmarks for the TRUS–CT image fusion. After TRUS–CT fusion, the TRUS-based prostate volume is deformed to the CT images for treatment planning. This method was first validated with a prostate-phantom study. In addition, a pilot study of ten patients undergoing HDR prostate brachytherapy was conducted to test its clinical feasibility. The accuracy of their approach was assessed through the locations of three implanted fiducial (gold) markers, as well as T2-weighted MR prostate images of patients. Results: For the phantom study, the target registration error (TRE) of gold-markers was 0.41 ± 0.11 mm. For the ten patients, the TRE of gold markers was 1.18 ± 0.26 mm; the prostate volume difference between the authors’ approach and the MRI-based volume was 7.28% ± 0

  5. B-Spline Finite Elements and their Efficiency in Solving Relativistic Mean Field Equations

    CERN Document Server

    Pöschl, W

    1997-01-01

    A finite element method using B-splines is presented and compared with a conventional finite element method of Lagrangian type. The efficiency of both methods has been investigated at the example of a coupled non-linear system of Dirac eigenvalue equations and inhomogeneous Klein-Gordon equations which describe a nuclear system in the framework of relativistic mean field theory. Although, FEM has been applied with great success in nuclear RMF recently, a well known problem is the appearance of spurious solutions in the spectra of the Dirac equation. The question, whether B-splines lead to a reduction of spurious solutions is analyzed. Numerical expenses, precision and behavior of convergence are compared for both methods in view of their use in large scale computation on FEM grids with more dimensions. A B-spline version of the object oriented C++ code for spherical nuclei has been used for this investigation.

  6. Shape blending of artistic brushstroke represented by disk B-spline curves

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper presents an algorithm for automatically generating in-between frames of two artistic brushstrokes.The basic ides of the algorithm is to represent the two key frames of artistic brushstrokes in disk B-spline curves,and then make blending of their geometric intrinsic variables.Given two key frames of artistic brushstrokes,the skeleton curves can be obtained by certain skeleton-besed techniques.After disk B-spline representation of the key frames is generated,interpolation of the intrinsic variables of the initial and the target disk B-spline curves is carried out.Examples show that this method can efficiently create in-between frames of artistic brushstrokes.

  7. A weighted extended B-spline solver for bending and buckling of stiffened plates

    CERN Document Server

    Verschaeve, Joris C G

    2015-01-01

    The weighted extended B-spline method [Hoellig (2003)] is applied to bending and buckling problems of plates with different shapes and stiffener arrangements. The discrete equations are obtained from the energy contributions of the different components constituting the system by means of the Rayleigh-Ritz approach. The pre-buckling or plane stress is computed by means of Airy's stress function. A boundary data extension algorithm for the weighted extended B-spline method is derived in order to solve for inhomogeneous Dirichlet boundary conditions. A series of benchmark tests is performed touching various aspects influencing the accuracy of the method.

  8. Fast Parallel Image Registration on CPU and GPU for Diagnostic Classification of Alzheimer's Disease

    Directory of Open Access Journals (Sweden)

    Denis P Shamonin

    2014-01-01

    Full Text Available Nonrigid image registration is an important, but time-consuming taskin medical image analysis. In typical neuroimaging studies, multipleimage registrations are performed, i.e. for atlas-based segmentationor template construction. Faster image registration routines wouldtherefore be beneficial.In this paper we explore acceleration of the image registrationpackage elastix by a combination of several techniques: iparallelization on the CPU, to speed up the cost function derivativecalculation; ii parallelization on the GPU building on andextending the OpenCL framework from ITKv4, to speed up the Gaussianpyramid computation and the image resampling step; iii exploitationof certain properties of the B-spline transformation model; ivfurther software optimizations.The accelerated registration tool is employed in a study ondiagnostic classification of Alzheimer's disease and cognitivelynormal controls based on T1-weighted MRI. We selected 299participants from the publicly available Alzheimer's DiseaseNeuroimaging Initiative database. Classification is performed with asupport vector machine based on gray matter volumes as a marker foratrophy. We evaluated two types of strategies (voxel-wise andregion-wise that heavily rely on nonrigid image registration.Parallelization and optimization resulted in an acceleration factorof 4-5x on an 8-core machine. Using OpenCL a speedup factor of ~2was realized for computation of the Gaussian pyramids, and 15-60 forthe resampling step, for larger images. The voxel-wise and theregion-wise classification methods had an area under thereceiver operator characteristic curve of 88% and 90%,respectively, both for standard and accelerated registration.We conclude that the image registration package elastix wassubstantially accelerated, with nearly identical results to thenon-optimized version. The new functionality will become availablein the next release of elastix as open source under the BSD license.

  9. A Mixed Basis Density Functional Approach for Low Dimensional Systems with B-splines

    CERN Document Server

    Ren, Chung-Yuan; Chang, Yia-Chung

    2014-01-01

    A mixed basis approach based on density functional theory is employed for low dimensional systems. The basis functions are taken to be plane waves for the periodic direction multiplied by B-spline polynomials in the non-periodic direction. B-splines have the following advantages:(1) the associated matrix elements are sparse, (2) B-splines possess a superior treatment of derivatives, (3) B-splines are not associated with atomic positions when the geometry structure is optimized, making the geometry optimization easy to implement. With this mixed basis set we can directly calculate the total energy of the system instead of using the conventional supercell model with a slab sandwiched between vacuum regions. A generalized Lanczos-Krylov iterative method is implemented for the diagonalization of the Hamiltonian matrix. To demonstrate the present approach, we apply it to study the C(001)-(2x1) surface with the norm-conserving pseudopotential, the n-type delta-doped graphene, and graphene nanoribbon with Vanderbilt...

  10. Calculations of Electron Structure of Endohedrally Confined Helium Atom with B-Spline Type Functions

    Institute of Scientific and Technical Information of China (English)

    QIAO HaoXue; SHI TingYun; LI BaiWen

    2002-01-01

    The B-spline basis set method is used to study the properties of helium confined endohedrally at thegeometrical centre of a fullerene. The boundary conditions of the wavefunctions can be simply satisfied with thismethod. From our results, the phenomenon of "mirror collapse" is found in the case of confining helium. The interestingbehaviors of confining helium are also discussed.

  11. Least square fitting of low resolution gamma ray spectra with cubic B-spline basis functions

    Institute of Scientific and Technical Information of China (English)

    ZHU Meng-Hua; LIU Liang-Gang; QI Dong-Xu; YOU Zhong; XU Ao-Ao

    2009-01-01

    In this paper,the least square fitting method with the cubic B-spline basis hmctioas is derived to reduce the influence of statistical fluctuations in the gamma ray spectra.The derived procedure is simple and automatic.The results show that this method is better than the convolution method with a sufficient reduction of statistical fluctuation.

  12. Constructing iterative non-uniform B-spline curve and surface to fit data points

    Institute of Scientific and Technical Information of China (English)

    LIN Hongwei; WANG Guojin; DONG Chenshi

    2004-01-01

    In this paper, based on the idea of profit and loss modification, we present the iterative non-uniform B-spline curve and surface to settle a key problem in computer aided geometric design and reverse engineering, that is, constructing the curve (surface)fitting (interpolating) a given ordered point set without solving a linear system. We start with a piece of initial non-uniform B-spline curve (surface) which takes the given point set as its control point set. Then by adjusting its control points gradually with iterative formula,we can get a group of non-uniform B-spline curves (surfaces) with gradually higher precision. In this paper, using modern matrix theory, we strictly prove that the limit curve (surface) of the iteration interpolates the given point set. The non-uniform B-spline curves (surfaces) generated with the iteration have many advantages, such as satisfying the NURBS standard, having explicit expression, gaining locality, and convexity preserving,etc.

  13. Non-Parametric Bayesian Registration (NParBR) of Body Tumors in DCE-MRI Data.

    Science.gov (United States)

    Pilutti, David; Strumia, Maddalena; Buchert, Martin; Hadjidemetriou, Stathis

    2016-04-01

    The identification of tumors in the internal organs of chest, abdomen, and pelvis anatomic regions can be performed with the analysis of Dynamic Contrast Enhanced Magnetic Resonance Imaging (DCE-MRI) data. The contrast agent is accumulated differently by pathologic and healthy tissues and that results in a temporally varying contrast in an image series. The internal organs are also subject to potentially extensive movements mainly due to breathing, heart beat, and peristalsis. This contributes to making the analysis of DCE-MRI datasets challenging as well as time consuming. To address this problem we propose a novel pairwise non-rigid registration method with a Non-Parametric Bayesian Registration (NParBR) formulation. The NParBR method uses a Bayesian formulation that assumes a model for the effect of the distortion on the joint intensity statistics, a non-parametric prior for the restored statistics, and also applies a spatial regularization for the estimated registration with Gaussian filtering. A minimally biased intra-dataset atlas is computed for each dataset and used as reference for the registration of the time series. The time series registration method has been tested with 20 datasets of liver, lungs, intestines, and prostate. It has been compared to the B-Splines and to the SyN methods with results that demonstrate that the proposed method improves both accuracy and efficiency. PMID:26672032

  14. 含局部空间约束的t分布混合模型的点集配准%Point Sets Non-rigid Registration Using Student0s-t Mixture Model with Spatial Constraints

    Institute of Scientific and Technical Information of China (English)

    周志勇; 李莉华; 郑健; 蒯多杰; 胡粟; 张涛

    2014-01-01

    基于高斯混合模型(Gaussian mixture model, GMM)的点集非刚性配准算法易受重尾点和异常点影响,提出含局部空间约束的t 分布混合模型的点集非刚性配准算法。通过期望最大化(Expectation maximization, EM)框架将高斯混合模型推广为t分布混合模型;把Dirichlet 分布作为浮动点的先验权重,并构造含局部空间约束性质的Dirichlet 分布参数。使用EM算法获得配准参数的闭合解;计算浮动点的自由度,改变其概率密度分布,避免异常点水平估计误差。实验表明,本文提出的配准算法具有配准误差小、鲁棒性好、抗干扰能力强等优点。%A robust non-rigid registration framework using the student0s-t mixture model with spatial constraints is proposed in this paper. The Gaussian mixture model which is vulnerable to outliers and data longer than normal tails is a special case of the student0s-t mixture model in theory. The Dirichlet distribution is used as a prior distribution to reduce the impact of outliers. The Dirichlet parameter set with spatial constrains is structured to incorporate the spatial information into the decision process. The closed form solution of the parameter set of the student0s-t mixture model is solved by re-parameterizing the student0s-t mixture model in the expectation maximization (EM) algorithm. The degree of freedom of each moving point is calculated to change the probability density to reduce the registration error. It can also avoid estimating the outlier level of data sets that may bring additional error. The experiments showed that this non-rigid registration algorithm has features of high-accuracy and good robustness compared to other point set registration approaches.

  15. Geometry Modeling of Ship Hull Based on Non-uniform B-spline

    Institute of Scientific and Technical Information of China (English)

    WANG Hu; ZOU Zao-jian

    2008-01-01

    In order to generate the three-dimensional (3-D) hull surface accurately and smoothly, a mixed method which is made up of non-uniform B-spline together with an iterative procedure was developed. By using the iterative method the data points on each section curve are calculated and the generalized waterlines and transverse section curves are determined. Then using the non-uniform B-spline expression, the control vertex net of the hull is calculated based on the generalized waterlines and section curves. A ship with tunnel stern was taken as test case. The numerical results prove that the proposed approach for geometry modeling of 3-D ship hull surface is accurate and effective.

  16. Left ventricular motion reconstruction with a prolate spheroidal B-spline model

    Energy Technology Data Exchange (ETDEWEB)

    Li Jin; Denney, Thomas S Jr [Electrical and Computer Engineering Department, 200 Broun Hall, Auburn University, AL 36849-5201 (United States)

    2006-02-07

    Tagged cardiac magnetic resonance (MR) imaging can non-invasively image deformation of the left ventricular (LV) wall. Three-dimensional (3D) analysis of tag data requires fitting a deformation model to tag lines in the image data. In this paper, we present a 3D myocardial displacement and strain reconstruction method based on a B-spline deformation model defined in prolate spheroidal coordinates, which more closely matches the shape of the LV wall than existing Cartesian or cylindrical coordinate models. The prolate spheroidal B-spline (PSB) deformation model also enforces smoothness across and can compute strain at the apex. The PSB reconstruction algorithm was evaluated on a previously published data set to allow head-to-head comparison of the PSB model with existing LV deformation reconstruction methods. We conclude that the PSB method can accurately reconstruct deformation and strain in the LV wall from tagged MR images and has several advantages relative to existing techniques.

  17. Left ventricular motion reconstruction with a prolate spheroidal B-spline model

    Science.gov (United States)

    Li, Jin; Denney, Thomas S., Jr.

    2006-02-01

    Tagged cardiac magnetic resonance (MR) imaging can non-invasively image deformation of the left ventricular (LV) wall. Three-dimensional (3D) analysis of tag data requires fitting a deformation model to tag lines in the image data. In this paper, we present a 3D myocardial displacement and strain reconstruction method based on a B-spline deformation model defined in prolate spheroidal coordinates, which more closely matches the shape of the LV wall than existing Cartesian or cylindrical coordinate models. The prolate spheroidal B-spline (PSB) deformation model also enforces smoothness across and can compute strain at the apex. The PSB reconstruction algorithm was evaluated on a previously published data set to allow head-to-head comparison of the PSB model with existing LV deformation reconstruction methods. We conclude that the PSB method can accurately reconstruct deformation and strain in the LV wall from tagged MR images and has several advantages relative to existing techniques.

  18. Ship hull plate processing surface fairing with constraints based on B-spline

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The problem of ship hull plate processing surface fairing with constraints based on B-spline is solved in this paper. The algorithm for B-spline curve fairing with constraints is one of the most common methods in plane curve fairing. The algorithm can be applied to global and local curve fairing. It can constrain the perturbation range of the control points and the shape variation of the curve, and get a better fairing result in plane curves. In this paper, a new fairing algorithm with constraints for curves and surfaces in space is presented. Then this method is applied to the experiments of ship hull plate processing surface. Finally numerical results are obtained to show the efficiency of this method.

  19. A new wavelet-based thin plate element using B-spline wavelet on the interval

    Science.gov (United States)

    Jiawei, Xiang; Xuefeng, Chen; Zhengjia, He; Yinghong, Zhang

    2008-01-01

    By interacting and synchronizing wavelet theory in mathematics and variational principle in finite element method, a class of wavelet-based plate element is constructed. In the construction of wavelet-based plate element, the element displacement field represented by the coefficients of wavelet expansions in wavelet space is transformed into the physical degree of freedoms in finite element space via the corresponding two-dimensional C1 type transformation matrix. Then, based on the associated generalized function of potential energy of thin plate bending and vibration problems, the scaling functions of B-spline wavelet on the interval (BSWI) at different scale are employed directly to form the multi-scale finite element approximation basis so as to construct BSWI plate element via variational principle. BSWI plate element combines the accuracy of B-spline functions approximation and various wavelet-based elements for structural analysis. Some static and dynamic numerical examples are studied to demonstrate the performances of the present element.

  20. River Flow Lane Detection and Kalman Filtering-Based B-Spline Lane Tracking

    Directory of Open Access Journals (Sweden)

    King Hann Lim

    2012-01-01

    Full Text Available A novel lane detection technique using adaptive line segment and river flow method is proposed in this paper to estimate driving lane edges. A Kalman filtering-based B-spline tracking model is also presented to quickly predict lane boundaries in consecutive frames. Firstly, sky region and road shadows are removed by applying a regional dividing method and road region analysis, respectively. Next, the change of lane orientation is monitored in order to define an adaptive line segment separating the region into near and far fields. In the near field, a 1D Hough transform is used to approximate a pair of lane boundaries. Subsequently, river flow method is applied to obtain lane curvature in the far field. Once the lane boundaries are detected, a B-spline mathematical model is updated using a Kalman filter to continuously track the road edges. Simulation results show that the proposed lane detection and tracking method has good performance with low complexity.

  1. B-Spline Active Contour with Handling of Topology Changes for Fast Video Segmentation

    Directory of Open Access Journals (Sweden)

    Frederic Precioso

    2002-06-01

    Full Text Available This paper deals with video segmentation for MPEG-4 and MPEG-7 applications. Region-based active contour is a powerful technique for segmentation. However most of these methods are implemented using level sets. Although level-set methods provide accurate segmentation, they suffer from large computational cost. We propose to use a regular B-spline parametric method to provide a fast and accurate segmentation. Our B-spline interpolation is based on a fixed number of points 2j depending on the level of the desired details. Through this spatial multiresolution approach, the computational cost of the segmentation is reduced. We introduce a length penalty. This results in improving both smoothness and accuracy. Then we show some experiments on real-video sequences.

  2. A Numerical Method Based on Daubechies Wavelet Basis and B-Spline Patches for Elasticity Problems

    Directory of Open Access Journals (Sweden)

    Yanan Liu

    2016-01-01

    Full Text Available The Daubechies (DB wavelets are used for solving 2D plane elasticity problems. In order to improve the accuracy and stability in computation, the DB wavelet scaling functions in 0,+∞ comprising boundary scaling functions are chosen as basis functions for approximation. The B-spline patches used in isogeometry analysis method are constructed to describe the problem domain. Through the isoparametric analysis approach, the function approximation and relevant computation based on DB wavelet functions are implemented on B-spline patches. This work makes an attempt to break the limitation that problems only can be discretized on uniform grids in the traditional wavelet numerical method. Numerical examples of 2D elasticity problems illustrate that this kind of analysis method is effective and stable.

  3. An efficient active B-spline/nurbs model for virtual sculpting

    OpenAIRE

    Moore, Patricia

    2013-01-01

    This thesis presents an Efficient Active B-Spline/Nurbs Model for Virtual Sculpting. In spite of the on-going rapid development of computer graphics and computer-aided design tools, 3D graphics designers still rely on non-intuitive modelling procedures for the creation and manipulation of freeform virtual content. The ’Virtual Sculpting' paradigm is a well-established mechanism for shielding designers from the complex mathematics that underpin freeform shape design. The premise is to emulate ...

  4. The Numerical Approach to the Fisher's Equation via Trigonometric Cubic B-spline Collocation Method

    OpenAIRE

    Ersoy, Ozlem; Dag, Idris

    2016-01-01

    In this study, we set up a numerical technique to get approximate solutions of Fisher's equation which is one of the most important model equation in population biology. We integrate the equation fully by using combination of the trigonometric cubic B-spline functions for space variable and Crank-Nicolson for the time integration. Numerical results have been presented to show the accuracy of the current algorithm. We have seen that the proposed technique is a good alternative to some existing...

  5. A mixed basis density functional approach for one-dimensional systems with B-splines

    Science.gov (United States)

    Ren, Chung-Yuan; Chang, Yia-Chung; Hsue, Chen-Shiung

    2016-05-01

    A mixed basis approach based on density functional theory is extended to one-dimensional (1D) systems. The basis functions here are taken to be the localized B-splines for the two finite non-periodic dimensions and the plane waves for the third periodic direction. This approach will significantly reduce the number of the basis and therefore is computationally efficient for the diagonalization of the Kohn-Sham Hamiltonian. For 1D systems, B-spline polynomials are particularly useful and efficient in two-dimensional spatial integrations involved in the calculations because of their absolute localization. Moreover, B-splines are not associated with atomic positions when the geometry structure is optimized, making the geometry optimization easy to implement. With such a basis set we can directly calculate the total energy of the isolated system instead of using the conventional supercell model with artificial vacuum regions among the replicas along the two non-periodic directions. The spurious Coulomb interaction between the charged defect and its repeated images by the supercell approach for charged systems can also be avoided. A rigorous formalism for the long-range Coulomb potential of both neutral and charged 1D systems under the mixed basis scheme will be derived. To test the present method, we apply it to study the infinite carbon-dimer chain, graphene nanoribbon, carbon nanotube and positively-charged carbon-dimer chain. The resulting electronic structures are presented and discussed in detail.

  6. A Vision Based Recognition of Indian Sign Language Alphabets and Numerals Using B-Spline Approximation

    Directory of Open Access Journals (Sweden)

    Geetha M

    2012-03-01

    Full Text Available Sign language is the most natural way of expression for the deaf community. The urge to support the integration of deaf people into the hearing society made the automatic sign language recognition, an area of interest for the researchers. Indian Sign Language (ISL is a visual-spatial language which provides linguistic information using hands, arms, facial expressions, and head/body postures. In this paper we propose a novel vision-based recognition of Indian Sign Language Alphabets and Numerals using B-Spline Approximation. Gestures of ISL alphabets are complex since it involves the gestures of both the hands together. Our algorithm approximates the boundary extracted from the Region of Interest, to a B-Spline curve by taking the Maximum Curvature Points (MCPs as the Control points. Then the B-Spline curve is subjected to iterations for smoothening resulting in the extraction of Key Maximum Curvature points (KMCPs, which are the key contributors of the gesture shape. Hence a translation & scale invariant feature vector is obtained from the spatial locations of the KMCPs in the 8 Octant Regions of the 2D Space which isgiven for classification.

  7. Design of Low-Pass Digital Differentiators Based on B-splines

    Directory of Open Access Journals (Sweden)

    Zijun He

    2014-07-01

    Full Text Available This paper describes a new method for designing low-pass differentiators that could be widely suitable for low-frequency signals with different sampling rates. The method is based on the differential property of convolution and the derivatives of B-spline bias functions. The first order differentiator is just constructed by the first derivative of the B-spline of degree 5 or 4. A high (>2 order low-pass differentiator is constructed by cascading two low order differentiators, of which the coefficients are obtained from the nth derivative of a B-spline of degree n+2 expanded by factor a. In this paper, the properties of the proposed differentiators were presented. In addition, we gave the examples of designing the first to sixth order differentiators, and several simulations, including the effects of the factor a on the results and the anti-noise capability of the proposed differentiators. These properties analysis and simulations indicate that the proposed differentiator can be applied to a wide range of low-frequency signals, and the trade-off between noise- reduction and signal preservation can be made by selecting the maximum allowable value of a.

  8. A B-Spline-Based Colocation Method to Approximate the Solutions to the Equations of Fluid Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Richard Wayne; Landon, Mark Dee

    1999-07-01

    The potential of a B-spline collocation method for numerically solving the equations of fluid dynamics is discussed. It is known that B-splines can resolve curves with drastically fewer data than can their standard shape function counterparts. This feature promises to allow much faster numerical simulations of fluid flow than standard finite volume/finite element methods without sacrificing accuracy. An example channel flow problem is solved using the method.

  9. A B-Spline-Based Colocation Method to Approximate the Solutions to the Equations of Fluid Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    M. D. Landon; R. W. Johnson

    1999-07-01

    The potential of a B-spline collocation method for numerically solving the equations of fluid dynamics is discussed. It is known that B-splines can resolve complex curves with drastically fewer data than can their standard shape function counterparts. This feature promises to allow much faster numerical simulations of fluid flow than standard finite volume/finite element methods without sacrificing accuracy. An example channel flow problem is solved using the method.

  10. Application of Hybrid Cubic B-Spline Collocation Approach for Solving a Generalized Nonlinear Klien-Gordon Equation

    OpenAIRE

    Shazalina Mat Zin; Ahmad Abd. Majid; Ahmad Izani Md. Ismail; Muhammad Abbas

    2014-01-01

    The generalized nonlinear Klien-Gordon equation is important in quantum mechanics and related fields. In this paper, a semi-implicit approach based on hybrid cubic B-spline is presented for the approximate solution of the nonlinear Klien-Gordon equation. The usual finite difference approach is used to discretize the time derivative while hybrid cubic B-spline is applied as an interpolating function in the space dimension. The results of applications to several test problems indicate good agre...

  11. Data assimilation using Bayesian filters and B-spline geological models

    KAUST Repository

    Duan, Lian

    2011-04-01

    This paper proposes a new approach to problems of data assimilation, also known as history matching, of oilfield production data by adjustment of the location and sharpness of patterns of geological facies. Traditionally, this problem has been addressed using gradient based approaches with a level set parameterization of the geology. Gradient-based methods are robust, but computationally demanding with real-world reservoir problems and insufficient for reservoir management uncertainty assessment. Recently, the ensemble filter approach has been used to tackle this problem because of its high efficiency from the standpoint of implementation, computational cost, and performance. Incorporation of level set parameterization in this approach could further deal with the lack of differentiability with respect to facies type, but its practical implementation is based on some assumptions that are not easily satisfied in real problems. In this work, we propose to describe the geometry of the permeability field using B-spline curves. This transforms history matching of the discrete facies type to the estimation of continuous B-spline control points. As filtering scheme, we use the ensemble square-root filter (EnSRF). The efficacy of the EnSRF with the B-spline parameterization is investigated through three numerical experiments, in which the reservoir contains a curved channel, a disconnected channel or a 2-dimensional closed feature. It is found that the application of the proposed method to the problem of adjusting facies edges to match production data is relatively straightforward and provides statistical estimates of the distribution of geological facies and of the state of the reservoir.

  12. B-Spline Filtering for Automatic Detection of Calcification Lesions in Mammograms

    Science.gov (United States)

    Bueno, G.; Sánchez, S.; Ruiz, M.

    2006-10-01

    Breast cancer continues to be an important health problem between women population. Early detection is the only way to improve breast cancer prognosis and significantly reduce women mortality. It is by using CAD systems that radiologist can improve their ability to detect, and classify lesions in mammograms. In this study the usefulness of using B-spline based on a gradient scheme and compared to wavelet and adaptative filtering has been investigated for calcification lesion detection and as part of CAD systems. The technique has been applied to different density tissues. A qualitative validation shows the success of the method.

  13. A numerical solution of the Burgers' equation using septic B-splines

    Energy Technology Data Exchange (ETDEWEB)

    Ramadan, Mohamed A. [Department of Mathematics, Faculty of Science, Menoufia University, Shiben El-Koom (Egypt)] e-mail: mramadan@mailer.eun.eg; El-Danaf, Talaat S. [Department of Mathematics, Faculty of Science, Menoufia University, Shiben El-Koom (Egypt); Abd Alaal, Faisal E.I. [Department of Mathematics, Faculty of Science, Menoufia University, Shiben El-Koom (Egypt)

    2005-11-01

    In this paper, numerical solutions of the nonlinear Burgers' equation are obtained by a method based on collocation of septic B-splines over finite elements. Applying the Von-Neumann stability analysis, the proposed method is shown to be unconditionally stable. Numerical solutions of the modified Burgers' equation are also obtained by making a simple change of the suggested numerical scheme for the Burgers' equation. The accuracy of the presented method is demonstrated by two test problems. The numerical results are found to be in good agreement with the exact solutions.

  14. Simulating the focusing of light onto 1D nanostructures with a B-spline modal method

    Science.gov (United States)

    Bouchon, P.; Chevalier, P.; Héron, S.; Pardo, F.; Pelouard, J.-L.; Haïdar, R.

    2015-03-01

    Focusing the light onto nanostructures thanks to spherical lenses is a first step to enhance the field, and is widely used in applications, in particular for enhancing non-linear effects like the second harmonic generation. Nonetheless, the electromagnetic response of such nanostructures, which have subwavelength patterns, to a focused beam can not be described by the simple ray tracing formalism. Here, we present a method to compute the response to a focused beam, based on the B-spline modal method. The simulation of a gaussian focused beam is obtained thanks to a truncated decomposition on plane waves computed on a single period, which limits the computation burden.

  15. A cubic B-spline Galerkin approach for the numerical simulation of the GEW equation

    Directory of Open Access Journals (Sweden)

    S. Battal Gazi Karakoç

    2016-02-01

    Full Text Available The generalized equal width (GEW wave equation is solved numerically by using lumped Galerkin approach with cubic B-spline functions. The proposed numerical scheme is tested by applying two test problems including single solitary wave and interaction of two solitary waves. In order to determine the performance of the algorithm, the error norms L2 and L∞ and the invariants I1, I2 and I3 are calculated. For the linear stability analysis of the numerical algorithm, von Neumann approach is used. As a result, the obtained findings show that the presented numerical scheme is preferable to some recent numerical methods.  

  16. Energy Spectra of the Confined Atoms Obtained by Using B-Splines

    Institute of Scientific and Technical Information of China (English)

    SHI Ting-Yun; BAO Cheng-Guang; LI Bai-Wen

    2001-01-01

    We have calculated the energy spectra of one- and two-electron atoms (ions) centered in an impenetrable spherical box by variational method with B-splines as basis functions. Accurate results are obtained for both large and small radii of confinement. The critical box radius of confined hydrogen atom is also calculated to show the usefulness of our method. A partial energy degeneracy in confined hydrogen atom is found when the radius of spherical box is equal to the distance at which a node of single-node wavefunctions of free hydrogen atom is located.

  17. Non-Stationary Hydrologic Frequency Analysis using B-Splines Quantile Regression

    Science.gov (United States)

    Nasri, B.; St-Hilaire, A.; Bouezmarni, T.; Ouarda, T.

    2015-12-01

    Hydrologic frequency analysis is commonly used by engineers and hydrologists to provide the basic information on planning, design and management of hydraulic structures and water resources system under the assumption of stationarity. However, with increasing evidence of changing climate, it is possible that the assumption of stationarity would no longer be valid and the results of conventional analysis would become questionable. In this study, we consider a framework for frequency analysis of extreme flows based on B-Splines quantile regression, which allows to model non-stationary data that have a dependence on covariates. Such covariates may have linear or nonlinear dependence. A Markov Chain Monte Carlo (MCMC) algorithm is used to estimate quantiles and their posterior distributions. A coefficient of determination for quantiles regression is proposed to evaluate the estimation of the proposed model for each quantile level. The method is applied on annual maximum and minimum streamflow records in Ontario, Canada. Climate indices are considered to describe the non-stationarity in these variables and to estimate the quantiles in this case. The results show large differences between the non-stationary quantiles and their stationary equivalents for annual maximum and minimum discharge with high annual non-exceedance probabilities. Keywords: Quantile regression, B-Splines functions, MCMC, Streamflow, Climate indices, non-stationarity.

  18. DBSR_HF: A B-spline Dirac-Hartree-Fock program

    Science.gov (United States)

    Zatsarinny, Oleg; Froese Fischer, Charlotte

    2016-05-01

    A B-spline version of a general Dirac-Hartree-Fock program is described. The usual differential equations are replaced by a set of generalized eigenvalue problems of the form (Ha -εa B) Pa = 0, where Ha and B are the Hamiltonian and overlap matrices, respectively, and Pa is the two-component relativistic orbit in the B-spline basis. A default universal grid allows for flexible adjustment to different nuclear models. When two orthogonal orbitals are both varied, the energy must also be stationary with respect to orthonormal transformations. At such a stationary point the off-diagonal Lagrange multipliers may be eliminated through projection operators. The self-consistent field procedure exhibits excellent convergence. Several atomic states can be considered simultaneously, including some configuration-interaction calculations. The program provides several options for the treatment of Breit interaction and QED corrections. The information about atoms up to Z = 104 is stored by the program. Along with a simple interface through command-line arguments, this information allows the user to run the program with minimal initial preparations.

  19. Railroad inspection based on ACFM employing a non-uniform B-spline approach

    Science.gov (United States)

    Chacón Muñoz, J. M.; García Márquez, F. P.; Papaelias, M.

    2013-11-01

    The stresses sustained by rails have increased in recent years due to the use of higher train speeds and heavier axle loads. For this reason surface and near-surface defects generate by Rolling Contact Fatigue (RCF) have become particularly significant as they can cause unexpected structural failure of the rail, resulting in severe derailments. The accident that took place in Hatfield, UK (2000), is an example of a derailment caused by the structural failure of a rail section due to RCF. Early detection of RCF rail defects is therefore of paramount importance to the rail industry. The performance of existing ultrasonic and magnetic flux leakage techniques in detecting rail surface-breaking defects, such as head checks and gauge corner cracking, is inadequate during high-speed inspection, while eddy current sensors suffer from lift-off effects. The results obtained through rail inspection experiments under simulated conditions using Alternating Current Field Measurement (ACFM) probes, suggest that this technique can be applied for the accurate and reliable detection of surface-breaking defects at high inspection speeds. This paper presents the B-Spline approach used for the accurate filtering the noise of the raw ACFM signal obtained during high speed tests to improve the reliability of the measurements. A non-uniform B-spline approximation is employed to calculate the exact positions and the dimensions of the defects. This method generates a smooth approximation similar to the ACFM dataset points related to the rail surface-breaking defect.

  20. Fuzzy B-spline optimization for urban slum three-dimensional reconstruction using ENVISAT satellite data

    Science.gov (United States)

    Marghany, Maged

    2014-06-01

    A critical challenges in urban aeras is slums. In fact, they are considered a source of crime and disease due to poor-quality housing, unsanitary conditions, poor infrastructures and occupancy security. The poor in the dense urban slums are the most vulnerable to infection due to (i) inadequate and restricted access to safety, drinking water and sufficient quantities of water for personal hygiene; (ii) the lack of removal and treatment of excreta; and (iii) the lack of removal of solid waste. This study aims to investigate the capability of ENVISAT ASAR satellite and Google Earth data for three-dimensional (3-D) slum urban reconstruction in developed countries such as Egypt. The main objective of this work is to utilize some 3-D automatic detection algorithm for urban slum in ENVISAT ASAR and Google Erath images were acquired in Cairo, Egypt using Fuzzy B-spline algorithm. The results show that the fuzzy algorithm is the best indicator for chaotic urban slum as it can discriminate between them from its surrounding environment. The combination of Fuzzy and B-spline then used to reconstruct 3-D of urban slum. The results show that urban slums, road network, and infrastructures are perfectly discriminated. It can therefore be concluded that the fuzzy algorithm is an appropriate algorithm for chaotic urban slum automatic detection in ENVSIAT ASAR and Google Earth data.

  1. Fuzzy B-spline optimization for urban slum three-dimensional reconstruction using ENVISAT satellite data

    International Nuclear Information System (INIS)

    A critical challenges in urban aeras is slums. In fact, they are considered a source of crime and disease due to poor-quality housing, unsanitary conditions, poor infrastructures and occupancy security. The poor in the dense urban slums are the most vulnerable to infection due to (i) inadequate and restricted access to safety, drinking water and sufficient quantities of water for personal hygiene; (ii) the lack of removal and treatment of excreta; and (iii) the lack of removal of solid waste. This study aims to investigate the capability of ENVISAT ASAR satellite and Google Earth data for three-dimensional (3-D) slum urban reconstruction in developed countries such as Egypt. The main objective of this work is to utilize some 3-D automatic detection algorithm for urban slum in ENVISAT ASAR and Google Erath images were acquired in Cairo, Egypt using Fuzzy B-spline algorithm. The results show that the fuzzy algorithm is the best indicator for chaotic urban slum as it can discriminate between them from its surrounding environment. The combination of Fuzzy and B-spline then used to reconstruct 3-D of urban slum. The results show that urban slums, road network, and infrastructures are perfectly discriminated. It can therefore be concluded that the fuzzy algorithm is an appropriate algorithm for chaotic urban slum automatic detection in ENVSIAT ASAR and Google Earth data

  2. B-splines as a Tool to Solve Constraints in Non-Hydrostatic Forecast Model

    CERN Document Server

    Subias, Alvaro

    2016-01-01

    Finite elements has been proven to be an useful tool to discretize the vertical coordinate in the hydrostatic forecast models allowing to define model variables in full levels so that no staggering is needed. In the non-hydrostatic case a constraint in the vertical operators appears (called C1) that does not allow to reduce the set of semi-implicit linear equations to a single equation in one variable as in the analytic case. Recently vertical finite elements based in B-splines have been used with an iterative method to relax the C1 constraint. In this paper we want to develop properly some representations of vertical operators in terms of B-splines in order to keep the C1-constraint. An invertibility relation between integral and derivative operators between vertical velocity and vertical divergence is also presented. The final scope of this paper is to provide a theoretical framework of development of finite element vertical operators to be implemented in the nh-Harmonie model

  3. Objective evaluation of the correction by non-rigid registration of abdominal organ motion in low-dose 4D dynamic contrast-enhanced CT

    Science.gov (United States)

    Piper, Jim; Ikeda, Yoshihiro; Fujisawa, Yasuko; Ohno, Yoshiharu; Yoshikawa, Takeshi; O'Neil, Alison; Poole, Ian

    2012-03-01

    We objectively evaluate a straightforward registration method for correcting respiration-induced movement of abdominal organs in CT perfusion studies by measuring the distributions of alignment errors between corresponding landmark pairs. We introduce the concept and describe the advantages of using the surface-normal component of distance between pairs of corresponding landmarks selected so that their surface normal is in one of the three coordinate axis directions, and show that such landmarks can be precisely placed with respect to the surface normal. Using a large population of landmark pairs on a substantial quantity of 4D dynamic contrast-enhanced CT volume data, we quantify the average alignment errors of abdominal organs that remain uncorrected by registration.

  4. G1 Continuity Conditions of B-spline Surfaces%B样条曲面间的G1连续条件

    Institute of Scientific and Technical Information of China (English)

    车翔玖; 梁学章

    2002-01-01

    According to the B-spline theory and Boehm algorithm, this paper presents severalnecessary and sufficient G1 continuity conditions between two adjacent B-spline surfaces. In orderto meet the need of application, a kind of sufficient conditions of G1 continuity are developed, anda kind of sufficient conditions of G1 continuity among N(N > 2) patch B-spline surfaces meetingat a common corner are given at the end.

  5. Analysis of a Gyroscope's Rotor Nonlinear Supported Magnetic Field Based on the B-Spline Wavelet-FEM

    Institute of Scientific and Technical Information of China (English)

    LIU Jian-feng; YUAN Gan-nan; HUANG Xu; YU Li

    2005-01-01

    A supported framework of a gyroscope′s rotor is designed and the B-Spline wavelet finite element model of nonlinear supported magnetic field is worked out. A new finite element space is studied in which the scaling function of the B-spline wavelet is considered as the shape function of a tetrahedron. The magnetic field is spited by an artificial absorbing body which used the condition of field radiating, so the solution is unique. The resolution is improved via the varying gradient of the B-spline function under the condition of unchanging gridding. So there are some advantages in dealing with the focus flux and a high varying gradient result from a nonlinear magnetic field. The result is more practical. Plots of flux and in the space is studied via simulating the supported system model. The results of the study are useful in the research of the supported magnetic system for the gyroscope rotor.

  6. The comparison of elastic band and B-Spline polynomials methods in smoothing process of collisionfree robot trajectory

    Directory of Open Access Journals (Sweden)

    D. Reclik

    2008-08-01

    Full Text Available Purpose: The main reason of this paper was to prepare the system, which tests the use of elastic band for smoothing the collision-free trajectory. The aided robot off-line programming system is based on NURBS and B-Spline curves. Because there is a lot of information in references about using elastic band algorithm, authors decided to compare these two methods. The most important criterion in robotics is having the smoothest possible robot trajectory, so as a standard there the NURBS curves (C2 smooth class were used.Design/methodology/approach: Pascal language compiler was used for research. All algorithms were coded in this programming language and compiled. Results were set in Microsoft Excel worksheet.Findings: Results show that calculations, which were made with B-Spline method, have taken less time than calculations based on elastic band curves. Moreover, the elastic band method gave the smoothest curves but only in geometrical sense, which is less important (the first and second derivate are not continuous, which is the most important issue in presented case. That is why it was found that using the B-Spline algorithm is a better solution, because it takes less time and gives better quality results.Research limitations/implications: The MS Windows application was created, which generates smooth curves (in geometrical sense by marking the interpolation base points which are calculated by the collision-free movement planner. This application generates curves by using both presented methods - B-Spline and elastic band. Both of these curves were compared in regard of standard deviation and variance of B-Spline and elastic band.Practical implications: Because the elastic band algorithm takes a lot of time (three times longer than B-Spline it is not used in the final application. The authors used B-Spline method to make smoother and optimized trajectory in application for off-line collision-free robot programming.Originality/value: This is a new

  7. Extended cubic B-spline method for solving a linear system of second-order boundary value problems.

    Science.gov (United States)

    Heilat, Ahmed Salem; Hamid, Nur Nadiah Abd; Ismail, Ahmad Izani Md

    2016-01-01

    A method based on extended cubic B-spline is proposed to solve a linear system of second-order boundary value problems. In this method, two free parameters, [Formula: see text] and [Formula: see text], play an important role in producing accurate results. Optimization of these parameters are carried out and the truncation error is calculated. This method is tested on three examples. The examples suggest that this method produces comparable or more accurate results than cubic B-spline and some other methods.

  8. Polychromatic sparse image reconstruction and mass attenuation spectrum estimation via B-spline basis function expansion

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Renliang, E-mail: Venliang@iastate.edu, E-mail: ald@iastate.edu; Dogandžić, Aleksandar, E-mail: Venliang@iastate.edu, E-mail: ald@iastate.edu [Iowa State University, Center for Nondestructive Evaluation, 1915 Scholl Road, Ames, IA 50011 (United States)

    2015-03-31

    We develop a sparse image reconstruction method for polychromatic computed tomography (CT) measurements under the blind scenario where the material of the inspected object and the incident energy spectrum are unknown. To obtain a parsimonious measurement model parameterization, we first rewrite the measurement equation using our mass-attenuation parameterization, which has the Laplace integral form. The unknown mass-attenuation spectrum is expanded into basis functions using a B-spline basis of order one. We develop a block coordinate-descent algorithm for constrained minimization of a penalized negative log-likelihood function, where constraints and penalty terms ensure nonnegativity of the spline coefficients and sparsity of the density map image in the wavelet domain. This algorithm alternates between a Nesterov’s proximal-gradient step for estimating the density map image and an active-set step for estimating the incident spectrum parameters. Numerical simulations demonstrate the performance of the proposed scheme.

  9. One Fairing Method of Cubic B-spline Curves Based on Weighted Progressive Iterative Approximation

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li; YANG Yan; LI Yuan-yuan; TAN Jie-qing

    2014-01-01

    A new method to the problem of fairing planar cubic B-spline curves is introduced in this paper. The method is based on weighted progressive iterative approximation (WPIA for short) and consists of following steps:finding the bad point which needs to fair, deleting the bad point, re-inserting a new data point to keep the structure of the curve and applying WPIA method with the new set of the data points to obtain the faired curve. The new set of the data points is formed by the rest of the original data points and the new inserted point. The method can be used for shape design and data processing. Numerical examples are provided to demonstrate the effectiveness of the method.

  10. B-spline parameterization of spatial response in a monolithic scintillation camera

    CERN Document Server

    Solovov, V; Chepel, V; Domingos, V; Martins, R

    2016-01-01

    A framework for parameterization of the light response functions (LRFs) in a scintillation camera was developed. It is based on approximation of the measured or simulated photosensor response with weighted sums of uniform cubic B-splines or their tensor products. The LRFs represented in this way are smooth, computationally inexpensive to evaluate and require much less memory than non-parametric alternatives. The parameters are found in a straightforward way by the linear least squares method. The use of linear fit makes the fitting process stable and predictable enough to be used in non-supervised mode. Several techniques that allow to reduce the storage and processing power requirements were developed. A software library for fitting simulated and measured light response with spline functions was developed and integrated into an open source software package ANTS2 designed for simulation and data processing for Anger camera-type detectors.

  11. Ionospheric scintillation modeling for high- and mid-latitude using B-spline technique

    Science.gov (United States)

    Priyadarshi, S.

    2015-09-01

    Ionospheric scintillation is a significant component of space-weather studies and serves as an estimate for the level of perturbation in the satellite radio wave signal caused due to small-scale ionospheric irregularities. B-spline functions are used on the GPS ground based data collected during the year 2007-2012 for modeling high- and mid-latitude ionospheric scintillation. Proposed model is for Hornsund, Svalbard and Warsaw, Poland. The input data used in this model were recorded by GSV 4004b receivers. For validation, results of this model are compared with the observation and other existing models. Physical behavior of the ionospheric scintillation during different seasons and geomagnetic conditions are discussed well. Model is found in good coherence with the ionospheric scintillation theory as well as to the accepted scintillation mechanism for high- and mid-latitude.

  12. Vibration analysis of composite pipes using the finite element method with B-spline wavelets

    Energy Technology Data Exchange (ETDEWEB)

    Oke, Wasiu A.; Khulief, Yehia A. [King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia)

    2016-02-15

    A finite element formulation using the B-spline wavelets on the interval is developed for modeling the free vibrations of composite pipes. The composite FRP pipe element is treated as a beam element. The finite pipe element is constructed in the wavelet space and then transformed to the physical space. Detailed expressions of the mass and stiffness matrices are derived for the composite pipe using the Bspline scaling and wavelet functions. Both Euler-Bernoulli and Timoshenko beam theories are considered. The generalized eigenvalue problem is formulated and solved to obtain the modal characteristics of the composite pipe. The developed wavelet-based finite element discretization scheme utilizes significantly less elements compared to the conventional finite element method for modeling composite pipes. Numerical solutions are obtained to demonstrate the accuracy of the developed element, which is verified by comparisons with some available results in the literature.

  13. AHT Bézier Curves and NUAHT B-Spline Curves

    Institute of Scientific and Technical Information of China (English)

    Gang Xu; Guo-Zhao Wang

    2007-01-01

    In this paper, we present two new unified mathematics models of conics and polynomial curves, called algebraic hyperbolic trigonometric ( AHT) Bézier curves and non-uniform algebraic hyperbolic trigonometric ( NUAHT) B-sptine curves of order n, which are generated over the space span{sin t, cos t, sinh t, cosh t, 1, t,..., tn-5}, n ≥ 5. The two kinds of curves share most of the properties as those of the Bézier curves and B-spline curves in polynomial space. In particular, they can represent exactly some remarkable transcendental curves such as the helix, the cycloid and the catenary. The subdivision formulae of these new kinds of curves are also given. The generations of the tensor product surfaces are straightforward. Using the new mathematics models, we present the control mesh representations of two classes of minimal surfaces.

  14. The Analysis of Curved Beam Using B-Spline Wavelet on Interval Finite Element Method

    Directory of Open Access Journals (Sweden)

    Zhibo Yang

    2014-01-01

    Full Text Available A B-spline wavelet on interval (BSWI finite element is developed for curved beams, and the static and free vibration behaviors of curved beam (arch are investigated in this paper. Instead of the traditional polynomial interpolation, scaling functions at a certain scale have been adopted to form the shape functions and construct wavelet-based elements. Different from the process of the direct wavelet addition in the other wavelet numerical methods, the element displacement field represented by the coefficients of wavelets expansions is transformed from wavelet space to physical space by aid of the corresponding transformation matrix. Furthermore, compared with the commonly used Daubechies wavelet, BSWI has explicit expressions and excellent approximation properties, which guarantee satisfactory results. Numerical examples are performed to demonstrate the accuracy and efficiency with respect to previously published formulations for curved beams.

  15. Robust engineering design optimization with non-uniform rational B-splines-based metamodels

    Science.gov (United States)

    Steuben, John C.; Turner, Cameron J.; Crawford, Richard H.

    2013-07-01

    Non-uniform rational B-splines (NURBs) demonstrate properties that make them attractive as metamodels, or surrogate models, for engineering design purposes. Previous research has resulted in the development of algorithms capable of fitting NURBs-based metamodels to engineering design spaces, and optimizing these models. This article presents an approach to robust optimization that employs NURBs-based metamodels. This robust optimization technique exploits the unique structure of NURBs-based metamodels to derive a simple but effective robustness metric. An algorithm is demonstrated that uses this metric to weigh robustness against optimality, and visualizes the trade-offs between these metamodel properties. This approach is demonstrated with test problems of increasing dimensionality, including several practical design challenges.

  16. 3D Profile Filter Algorithm Based on Parallel Generalized B-spline Approximating Gaussian

    Institute of Scientific and Technical Information of China (English)

    REN Zhiying; GAO Chenghui; SHEN Ding

    2015-01-01

    Currently, the approximation methods of the Gaussian filter by some other spline filters have been developed. However, these methods are only suitable for the study of one-dimensional filtering, when these methods are used for three-dimensional filtering, it is found that a rounding error and quantization error would be passed to the next in every part. In this paper, a new and high-precision implementation approach for Gaussian filter is described, which is suitable for three-dimensional reference filtering. Based on the theory of generalized B-spline function and the variational principle, the transmission characteristics of a digital filter can be changed through the sensitivity of the parameters (t1, t2), and which can also reduce the rounding error and quantization error by the filter in a parallel form instead of the cascade form. Finally, the approximation filter of Gaussian filter is obtained. In order to verify the feasibility of the new algorithm, the reference extraction of the conventional methods are also used and compared. The experiments are conducted on the measured optical surface, and the results show that the total calculation by the new algorithm only requires 0.07 s for 480´480 data points;the amplitude deviation between the reference of the parallel form filter and the Gaussian filter is smaller;the new method is closer to the characteristic of the Gaussian filter through the analysis of three-dimensional roughness parameters, comparing with the cascade generalized B-spline approximating Gaussian. So the new algorithm is also efficient and accurate for the implementation of Gaussian filter in the application of surface roughness measurement.

  17. Hyperspectral imaging for cancer surgical margin delineation: registration of hyperspectral and histological images

    Science.gov (United States)

    Lu, Guolan; Halig, Luma; Wang, Dongsheng; Chen, Zhuo G.; Fei, Baowei

    2014-03-01

    The determination of tumor margins during surgical resection remains a challenging task. A complete removal of malignant tissue and conservation of healthy tissue is important for the preservation of organ function, patient satisfaction, and quality of life. Visual inspection and palpation is not sufficient for discriminating between malignant and normal tissue types. Hyperspectral imaging (HSI) technology has the potential to noninvasively delineate surgical tumor margin and can be used as an intra-operative visual aid tool. Since histological images provide the ground truth of cancer margins, it is necessary to warp the cancer regions in ex vivo histological images back to in vivo hyperspectral images in order to validate the tumor margins detected by HSI and to optimize the imaging parameters. In this paper, principal component analysis (PCA) is utilized to extract the principle component bands of the HSI images, which is then used to register HSI images with the corresponding histological image. Affine registration is chosen to model the global transformation. A B-spline free form deformation (FFD) method is used to model the local non-rigid deformation. Registration experiment was performed on animal hyperspectral and histological images. Experimental results from animals demonstrated the feasibility of the hyperspectral imaging method for cancer margin detection.

  18. Serial Section Registration of Axonal Confocal Microscopy Datasets for Long-Range Neural Circuit Reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Hogrebe, Luke; Paiva, Antonio R.; Jurrus, Elizabeth R.; Christensen, Cameron; Bridge, Michael; Dai, Li; Pfeiffer, Rebecca; Hof, Patrick; Roysam, Badrinath; Korenberg, Julie; Tasdizen, Tolga

    2012-06-15

    In the context of long-range digital neural circuit reconstruction, this paper investigates an approach for registering axons across histological serial sections. Tracing distinctly labeled axons over large distances allows neuroscientists to study very explicit relationships between the brain's complex interconnects and, for example, diseases or aberrant development. Large scale histological analysis requires, however, that the tissue be cut into sections. In immunohistochemical studies thin sections are easily distorted due to the cutting, preparation, and slide mounting processes. In this work we target the registration of thin serial sections containing axons. Sections are first traced to extract axon centerlines, and these traces are used to define registration landmarks where they intersect section boundaries. The trace data also provides distinguishing information regarding an axon's size and orientation within a section. We propose the use of these features when pairing axons across sections in addition to utilizing the spatial relationships amongst the landmarks. The global rotation and translation of an unregistered section are accounted for using a random sample consensus (RANSAC) based technique. An iterative nonrigid refinement process using B-spline warping is then used to reconnect axons and produce the sought after connectivity information.

  19. First Principles Calculations of the Double Photoionization of Atoms and Molecules using B-splines and Exterior Complex Scaling

    International Nuclear Information System (INIS)

    We report a fully ab initio implementation of exterior complex scaling in B-splines to evaluate total, singly and triply differential cross sections in double photoionization problems. Results for He and H2 double photoionization are presented and compared with experiment

  20. Merging quantum-chemistry with B-splines to describe molecular photoionization

    Science.gov (United States)

    Argenti, L.; Marante, C.; Klinker, M.; Corral, I.; Gonzalez, J.; Martin, F.

    2016-05-01

    Theoretical description of observables in attosecond pump-probe experiments requires a good representation of the system's ionization continuum. For polyelectronic atoms and molecules, however, this is still a challenge, due to the complicated short-range structure of correlated electronic wavefunctions. Whereas quantum chemistry packages (QCP) implementing sophisticated methods to compute bound electronic molecular states are well established, comparable tools for the continuum are not widely available yet. To tackle this problem, we have developed a new approach that, by means of a hybrid Gaussian-B-spline basis, interfaces existing QCPs with close-coupling scattering methods. To illustrate the viability of this approach, we report results for the multichannel ionization of the helium atom and of the hydrogen molecule that are in excellent agreement with existing accurate benchmarks. These findings, together with the flexibility of QCPs, make of this approach a good candidate for the theoretical study of the ionization of poly-electronic systems. FP7/ERC Grant XCHEM 290853.

  1. Certified Approximation of Parametric Space Curves with Cubic B-spline Curves

    CERN Document Server

    Shen, Liyong; Gao, Xiao-Shan

    2012-01-01

    Approximating complex curves with simple parametric curves is widely used in CAGD, CG, and CNC. This paper presents an algorithm to compute a certified approximation to a given parametric space curve with cubic B-spline curves. By certified, we mean that the approximation can approximate the given curve to any given precision and preserve the geometric features of the given curve such as the topology, singular points, etc. The approximated curve is divided into segments called quasi-cubic B\\'{e}zier curve segments which have properties similar to a cubic rational B\\'{e}zier curve. And the approximate curve is naturally constructed as the associated cubic rational B\\'{e}zier curve of the control tetrahedron of a quasi-cubic curve. A novel optimization method is proposed to select proper weights in the cubic rational B\\'{e}zier curve to approximate the given curve. The error of the approximation is controlled by the size of its tetrahedron, which converges to zero by subdividing the curve segments. As an applic...

  2. N-dimensional non uniform rational B-splines for metamodeling

    Energy Technology Data Exchange (ETDEWEB)

    Turner, Cameron J [Los Alamos National Laboratory; Crawford, Richard H [UT - AUSTIN

    2008-01-01

    Non Uniform Rational B-splines (NURBs) have unique properties that make them attractive for engineering metamodeling applications. NURBs are known to accurately model many different continuous curve and surface topologies in 1-and 2-variate spaces. However, engineering metamodels of the design space often require hypervariate representations of multidimensional outputs. In essence, design space metamodels are hyperdimensional constructs with a dimensionality determined by their input and output variables. To use NURBs as the basis for a metamodel in a hyperdimensional space, traditional geometric fitting techniques must be adapted to hypervariate and hyperdimensional spaces composed of both continuous and discontinuous variable types. In this paper, we describe the necessary adaptations for the development of a NURBs-based metamodel called a Hyperdimensional Performance Model or HyPerModel. HyPerModels are capable of accurately and reliably modeling nonlinear hyperdimensional objects defined by both continuous and discontinuous variables of a wide variety of topologies, such as those that define typical engineering design spaces. We demonstrate this ability by successfully generating accurate HyPerModels of 10 trial functions laying the foundation for future work with N-dimensional NURBs in design space applications.

  3. n-dimensional non uniform rational b-splines for metamodeling

    Energy Technology Data Exchange (ETDEWEB)

    Turner, Cameron J [Los Alamos National Laboratory; Crawford, Richard H [UT-AUSTIN

    2008-01-01

    Non Uniform Rational B-splines (NURBs) have unique properties that make them attractive for engineering metamodeling applications. NURBs are known to accurately model many different continuous curve and surface topologies in 1- and 2-variate spaces. However, engineering metamodels of the design space often require hypervariate representations of multidimensional outputs. In essence, design space metamodels are hyperdimensional constructs with a dimensionality determined by their input and output variables. To use NURBs as the basis for a metamodel in a hyperdimensional space, traditional geometric fitting techniques must be adapted to hypervariate and hyperdimensional spaces composed of both continuous and discontinuous variable types. In this paper, they describe the necessary adaptations for the development of a NURBs-based metamodel called a Hyperdimensional Performance Model or HyPerModel. HyPerModels are capable of accurately and reliably modeling nonlinear hyperdimensional objects defined by both continuous and discontinuous variables of a wide variety of topologies, such as those that define typical engineering design spaces. They demonstrate this ability by successfully generating accurate HyPerModels of 10 trial functions laying the foundation for future work with N-dimensional NURBs in design space applications.

  4. CT segmentation of dental shapes by anatomy-driven reformation imaging and B-spline modelling.

    Science.gov (United States)

    Barone, S; Paoli, A; Razionale, A V

    2016-06-01

    Dedicated imaging methods are among the most important tools of modern computer-aided medical applications. In the last few years, cone beam computed tomography (CBCT) has gained popularity in digital dentistry for 3D imaging of jawbones and teeth. However, the anatomy of a maxillofacial region complicates the assessment of tooth geometry and anatomical location when using standard orthogonal views of the CT data set. In particular, a tooth is defined by a sub-region, which cannot be easily separated from surrounding tissues by only considering pixel grey-intensity values. For this reason, an image enhancement is usually necessary in order to properly segment tooth geometries. In this paper, an anatomy-driven methodology to reconstruct individual 3D tooth anatomies by processing CBCT data is presented. The main concept is to generate a small set of multi-planar reformation images along significant views for each target tooth, driven by the individual anatomical geometry of a specific patient. The reformation images greatly enhance the clearness of the target tooth contours. A set of meaningful 2D tooth contours is extracted and used to automatically model the overall 3D tooth shape through a B-spline representation. The effectiveness of the methodology has been verified by comparing some anatomy-driven reconstructions of anterior and premolar teeth with those obtained by using standard tooth segmentation tools. Copyright © 2015 John Wiley & Sons, Ltd.

  5. Numerical simulation of two dimensional sine-Gordon solitons using modified cubic B-spline differential quadrature method

    Directory of Open Access Journals (Sweden)

    H. S. Shukla

    2015-01-01

    Full Text Available In this paper, a modified cubic B-spline differential quadrature method (MCB-DQM is employed for the numerical simulation of two-space dimensional nonlinear sine-Gordon equation with appropriate initial and boundary conditions. The modified cubic B-spline works as a basis function in the differential quadrature method to compute the weighting coefficients. Accordingly, two dimensional sine-Gordon equation is transformed into a system of second order ordinary differential equations (ODEs. The resultant system of ODEs is solved by employing an optimal five stage and fourth-order strong stability preserving Runge–Kutta scheme (SSP-RK54. Numerical simulation is discussed for both damped and undamped cases. Computational results are found to be in good agreement with the exact solution and other numerical results available in the literature.

  6. Numerical solution of two dimensional coupled viscous Burger equation using modified cubic B-spline differential quadrature method

    Directory of Open Access Journals (Sweden)

    H. S. Shukla

    2014-11-01

    Full Text Available In this paper, a numerical solution of two dimensional nonlinear coupled viscous Burger equation is discussed with appropriate initial and boundary conditions using the modified cubic B-spline differential quadrature method. In this method, the weighting coefficients are computed using the modified cubic B-spline as a basis function in the differential quadrature method. Thus, the coupled Burger equation is reduced into a system of ordinary differential equations. An optimal five stage and fourth-order strong stability preserving Runge–Kutta scheme is applied for solving the resulting system of ordinary differential equations. The accuracy of the scheme is illustrated by taking two numerical examples. Computed results are compared with the exact solutions and other results available in literature. Obtained numerical result shows that the described method is efficient and reliable scheme for solving two dimensional coupled viscous Burger equation.

  7. Edge detection of molten pool and weld line for CO2 welding based on B-spline wavelet

    Institute of Scientific and Technical Information of China (English)

    薛家祥; 贾林; 李海宝; 张丽玲

    2004-01-01

    Due to the disturbances of spatters, dusts and strong arc light, it is difficult to detect the molten pool edge and the weld line location in CO2 welding processes. The median filtering and self-multiplication was employed to preprocess the image of the CO2 welding in order to detect effectively the edge of molten pool and the location of weld line. The B-spline wavelet algorithm has been investigated, the influence of different scales and thresholds on the results of the edge detection have been compared and analyzed. The experimental results show that better performance to extract the edge of the molten pool and the location of weld line can be obtained by using the B-spline wavelet transform. The proposed edge detection approach can be further applied to the control of molten depth and the seam tracking.

  8. Investigation of electron and hydrogenic-donor states confined in a permeable spherical box using B-splines

    Directory of Open Access Journals (Sweden)

    T Nikbakht

    2012-12-01

    Full Text Available   Effects of quantum size and potential shape on the spectra of an electron and a hydrogenic-donor at the center of a permeable spherical cavity have been calculated, using linear variational method. B-splines have been used as basis functions. By extensive convergence tests and comparing with other results given in the literature, the validity and efficiency of the method were confirmed.

  9. Brownian Warps for Non-Rigid Registration

    DEFF Research Database (Denmark)

    Nielsen, Mads; Johansen, Peter; Jackson, Andrew D.;

    2008-01-01

    A Brownian motion model in the group of diffeomorphisms has been introduced as inducing a least committed prior on warps. This prior is source-destination symmetric, fulfills a natural semi-group property for warps, and with probability 1 creates invertible warps. Using this as a least committed ...

  10. Generation of global VTEC maps from low latency GNSS observations based on B-spline modelling and Kalman filtering

    Science.gov (United States)

    Erdogan, Eren; Dettmering, Denise; Limberger, Marco; Schmidt, Michael; Seitz, Florian; Börger, Klaus; Brandert, Sylvia; Görres, Barbara; Kersten, Wilhelm F.; Bothmer, Volker; Hinrichs, Johannes; Venzmer, Malte

    2015-04-01

    In May 2014 DGFI-TUM (the former DGFI) and the German Space Situational Awareness Centre (GSSAC) started to develop an OPerational Tool for Ionospheric Mapping And Prediction (OPTIMAP); since November 2014 the Institute of Astrophysics at the University of Göttingen (IAG) joined the group as the third partner. This project aims on the computation and prediction of maps of the vertical total electron content (VTEC) and the electron density distribution of the ionosphere on a global scale from both various space-geodetic observation techniques such as GNSS and satellite altimetry as well as Sun observations. In this contribution we present first results, i.e. a near-real time processing framework for generating VTEC maps by assimilating GNSS (GPS, GLONASS) based ionospheric data into a two-dimensional global B-spline approach. To be more specific, the spatial variations of VTEC are modelled by trigonometric B-spline functions in longitude and by endpoint-interpolating polynomial B-spline functions in latitude, respectively. Since B-spline functions are compactly supported and highly localizing our approach can handle large data gaps appropriately and, thus, provides a better approximation of data with heterogeneous density and quality compared to the commonly used spherical harmonics. The presented method models temporal variations of VTEC inside a Kalman filter. The unknown parameters of the filter state vector are composed of the B-spline coefficients as well as the satellite and receiver DCBs. To approximate the temporal variation of these state vector components as part of the filter the dynamical model has to be set up. The current implementation of the filter allows to select between a random walk process, a Gauss-Markov process and a dynamic process driven by an empirical ionosphere model, e.g. the International Reference Ionosphere (IRI). For running the model ionospheric input data is acquired from terrestrial GNSS networks through online archive systems

  11. Free Form Deformation–Based Image Registration Improves Accuracy of Traction Force Microscopy

    Science.gov (United States)

    Jorge-Peñas, Alvaro; Izquierdo-Alvarez, Alicia; Aguilar-Cuenca, Rocio; Vicente-Manzanares, Miguel; Garcia-Aznar, José Manuel; Van Oosterwyck, Hans; de-Juan-Pardo, Elena M.; Ortiz-de-Solorzano, Carlos; Muñoz-Barrutia, Arrate

    2015-01-01

    Traction Force Microscopy (TFM) is a widespread method used to recover cellular tractions from the deformation that they cause in their surrounding substrate. Particle Image Velocimetry (PIV) is commonly used to quantify the substrate’s deformations, due to its simplicity and efficiency. However, PIV relies on a block-matching scheme that easily underestimates the deformations. This is especially relevant in the case of large, locally non-uniform deformations as those usually found in the vicinity of a cell’s adhesions to the substrate. To overcome these limitations, we formulate the calculation of the deformation of the substrate in TFM as a non-rigid image registration process that warps the image of the unstressed material to match the image of the stressed one. In particular, we propose to use a B-spline -based Free Form Deformation (FFD) algorithm that uses a connected deformable mesh to model a wide range of flexible deformations caused by cellular tractions. Our FFD approach is validated in 3D fields using synthetic (simulated) data as well as with experimental data obtained using isolated endothelial cells lying on a deformable, polyacrylamide substrate. Our results show that FFD outperforms PIV providing a deformation field that allows a better recovery of the magnitude and orientation of tractions. Together, these results demonstrate the added value of the FFD algorithm for improving the accuracy of traction recovery. PMID:26641883

  12. Efficient Constrained Local Model Fitting for Non-Rigid Face Alignment

    OpenAIRE

    Lucey, Simon; Wang, Yang; Cox, Mark; Sridharan, Sridha; Cohn, Jeffery F.

    2009-01-01

    Active appearance models (AAMs) have demonstrated great utility when being employed for non-rigid face alignment/tracking. The “simultaneous” algorithm for fitting an AAM achieves good non-rigid face registration performance, but has poor real time performance (2-3 fps). The “project-out” algorithm for fitting an AAM achieves faster than real time performance (> 200 fps) but suffers from poor generic alignment performance. In this paper we introduce an extension to a discriminative method for...

  13. PetIGA-MF: a multi-field high-performance toolbox for structure-preserving B-splines spaces

    KAUST Repository

    Sarmiento, A.F.

    2016-10-01

    We describe a high-performance solution framework for isogeometric discrete differential forms based on B-splines: PetIGA-MF. Built on top of PetIGA, an open-source library we have built and developed over the last decade, PetIGA-MF is a general multi-field discretization tool. To test the capabilities of our implementation, we solve different viscous flow problems such as Darcy, Stokes, Brinkman, and Navier-Stokes equations. Several convergence benchmarks based on manufactured solutions are presented assuring optimal convergence rates of the approximations, showing the accuracy and robustness of our solver.

  14. A scalable block-preconditioning strategy for divergence-conforming B-spline discretizations of the Stokes problem

    KAUST Repository

    Côrtes, A.M.A.

    2016-10-01

    The recently introduced divergence-conforming B-spline discretizations allow the construction of smooth discrete velocity-pressure pairs for viscous incompressible flows that are at the same time inf−supinf−sup stable and pointwise divergence-free. When applied to the discretized Stokes problem, these spaces generate a symmetric and indefinite saddle-point linear system. The iterative method of choice to solve such system is the Generalized Minimum Residual Method. This method lacks robustness, and one remedy is to use preconditioners. For linear systems of saddle-point type, a large family of preconditioners can be obtained by using a block factorization of the system. In this paper, we show how the nesting of “black-box” solvers and preconditioners can be put together in a block triangular strategy to build a scalable block preconditioner for the Stokes system discretized by divergence-conforming B-splines. Besides the known cavity flow problem, we used for benchmark flows defined on complex geometries: an eccentric annulus and hollow torus of an eccentric annular cross-section.

  15. THE CONSTRUCTION OF WAVELET-BASED TRUNCATED CONICAL SHELL ELEMENT USING B-SPLINE WAVELET ON THE INTERVAL

    Institute of Scientific and Technical Information of China (English)

    Xiang Jiawei; He Zhengjia; Chen Xuefeng

    2006-01-01

    Based on B-spline wavelet on the interval (BSWI), two classes of truncated conical shell elements were constructed to solve axisymmetric problems, i.e. BSWI thin truncated conical shell element and BSWI moderately thick truncated conical shell element with independent slopedeformation interpolation. In the construction of wavelet-based element, instead of traditional polynomial interpolation, the scaling functions of BSWI were employed to form the shape functions through the constructed elemental transformation matrix, and then construct BSWI element via the variational principle. Unlike the process of direct wavelets adding in the wavelet Galerkin method, the elemental displacement field represented by the coefficients of wavelets expansion was transformed into edges and internal modes via the constructed transformation matrix. BSWI element combines the accuracy of B-spline function approximation and various wavelet-based lements for structural analysis. Some static and dynamic numerical examples of conical shells were studied to demonstrate the present element with higher efficiency and precision than the traditional element.

  16. An Efficient Switching Filter Based on Cubic B-Spline for Removal of Salt-and-Pepper Noise

    Directory of Open Access Journals (Sweden)

    Hani M. Ibrahem

    2014-04-01

    Full Text Available In this paper, an efficient filter method for salt-and-pepper noise removal is proposed. This method is developed by using cubic B-spline. A noise detector is employed to check whether the selected pixel is noisy or noise free. In this method, noise free pixels are left unaltered. Since not every pixel is filtered, undue distortion can be avoided. Noise pixels are subjected to the filtering operation to reconstruct the intensity values of the noisy pixels. The noise free pixels are only considered in the filter operation. The cubic B-spline is used as a fitting function to generate additional values within the noise free pixels. The noisy pixel is replaced by the mean value of these pixel values. The window size is selected as 3 X 3 in the first step. If all pixels within the window are considered to be noise, then change the selected window size to 5 X 5. If all the pixels within this window are considered to be noise, then the noisy pixel is replaced by the previous resultant pixel. Comparison of the given filter with other existing filters is provided in this paper. The results demonstrate that the proposed technique can obtain better performances than other existing denoising techniques. As a result of this, the proposed method removes the noise effectively even at noise level as high as 97%.

  17. Generation of Discrete Bicubic G1 B-Spline Ship Hullform Surfaces from a Given Curve Network Using Virtual Iso-Parametric Curves

    Institute of Scientific and Technical Information of China (English)

    Joong-Hyun Rhim; Doo-Yeoun Cho; Kyu-Yeul Lee; Tae-Wan Kim

    2006-01-01

    We propose a method that automatically generates discrete bicubic G1 continuous B-spline surfaces that interpolate the curve network of a ship hullform. First, the curves in the network are classified into two types: boundary curves and "reference curves". The boundary curves correspond to a set of rectangular (or triangular) topological type that can be represented with tensor-product (or degenerate) B-spline surface patches. Next, in the interior of the patches,surface fitting points and cross boundary derivatives are estimated from the reference curves by constructing "virtual" isoparametric curves. Finally, a discrete G1 continuous B-spline surface is generated by a surface fitting algorithm. Several smooth ship hullform surfaces generated from curve networks corresponding to actual ship hullforms demonstrate the quality of the method.

  18. C-B样条曲线的分割和拼接%Arbitrary Subdivision Algorithm and Joining of C-B-Spline

    Institute of Scientific and Technical Information of China (English)

    宋丽平

    2011-01-01

    曲线曲面造型中设计复杂的自由曲线时,单段曲线已不能满足外形设计的要求,因而在实际造型中,经常采用曲线的分割和拼接.C-B样条理论是曲线曲面造型的一项重要内容.在对C-B样条基函数及曲线端点特性分析的基础上,提出了C-B样条曲线的任意分割算法,并对C-B样条曲线间进行了G1拼接.给出了 B样条曲线和C-B样条曲线G1和G2光滑拼接的几何条件.采用分割和拼接技术会增加C-B样条曲线的灵活性,所得结论具有明确的几何意义,并可以进一步推广到C-B样条曲面造型中.%The single curve already can' t satisfy the requirements of shape design when designing complex free curve in curve/surface modeling. Thus in the actual modeling, C-B-spline theory is an important content of curve/surface modeling. Propose the algorithm of arbitrarily divided when analysing C-B-spline basis functions,then splicing between two C-B-spline. In addition,give geometry conditions about B-spline curves and C-B-spline curves. The results are benefit for the shape modification, and they can also be extended to surface modeling with C-B-spline.

  19. Evaluation of Registration Methods on Thoracic CT

    DEFF Research Database (Denmark)

    Murphy, K.; van Ginneken, B.; Reinhardt, J.;

    2011-01-01

    EMPIRE10 (Evaluation of Methods for Pulmonary Image REgistration 2010) is a public platform for fair and meaningful comparison of registration algorithms which are applied to a database of intra-patient thoracic CT image pairs. Evaluation of non-rigid registration techniques is a non trivial task...

  20. PEMODELAN B-SPLINE DAN MARS PADA NILAI UJIAN MASUK TERHADAP IPK MAHASISWA JURUSAN DISAIN KOMUNIKASI VISUAL UK. PETRA SURABAYA

    Directory of Open Access Journals (Sweden)

    I Nyoman Budiantara

    2006-01-01

    Full Text Available Regression analysis is constructed for capturing the influences of independent variables to dependent ones. It can be done by looking at the relationship between those variables. This task of approximating the mean function can be done essentially in two ways. The quiet often use parametric approach is to assume that the mean curve has some prespecified functional forms. Alternatively, nonparametric approach, .i.e., without reference to a specific form, is used when there is no information of the regression function form (Haerdle, 1990. Therefore nonparametric approach has more flexibilities than the parametric one. The aim of this research is to find the best fit model that captures relationship between admission test score to the GPA. This particular data was taken from the Department of Design Communication and Visual, Petra Christian University, Surabaya for year 1999. Those two approaches were used here. In the parametric approach, we use simple linear, quadric cubic regression, and in the nonparametric ones, we use B-Spline and Multivariate Adaptive Regression Splines (MARS. Overall, the best model was chosen based on the maximum determinant coefficient. However, for MARS, the best model was chosen based on the GCV, minimum MSE, maximum determinant coefficient. Abstract in Bahasa Indonesia : Analisa regresi digunakan untuk melihat pengaruh variabel independen terhadap variabel dependent dengan terlebih dulu melihat pola hubungan variabel tersebut. Hal ini dapat dilakukan dengan melalui dua pendekatan. Pendekatan yang paling umum dan seringkali digunakan adalah pendekatan parametrik. Pendekatan parametrik mengasumsikan bentuk model sudah ditentukan. Apabila tidak ada informasi apapun tentang bentuk dari fungsi regresi, maka pendekatan yang digunakan adalah pendekatan nonparametrik. (Haerdle, 1990. Karena pendekatan tidak tergantung pada asumsi bentuk kurva tertentu, sehingga memberikan fleksibelitas yang lebih besar. Tujuan penelitian ini

  1. Electromagnetic modelization of spherical focusing on a one-dimensional grating thanks to a conical B-spline modal method.

    Science.gov (United States)

    Chevalier, Paul; Bouchon, Patrick; Pardo, Fabrice; Haïdar, Riad

    2014-08-01

    Focusing light onto nanostructures thanks to spherical lenses is a first step in enhancing the field and is widely used in applications. Nonetheless, the electromagnetic response of such nanostructures, which have subwavelength patterns, to a focused beam cannot be described by the simple ray tracing formalism. Here, we present a method for computing the response to a focused beam, based on the B-spline modal method adapted to nanostructures in conical mounting. The eigenmodes are computed in each layer for both polarizations and are then combined for the computation of scattering matrices. The simulation of a Gaussian focused beam is obtained thanks to a truncated decomposition into plane waves computed on a single period, which limits the computation burden. PMID:25121523

  2. A finite strain Eulerian formulation for compressible and nearly incompressible hyperelasticity using high-order B-spline finite elements

    KAUST Repository

    Duddu, Ravindra

    2011-10-05

    We present a numerical formulation aimed at modeling the nonlinear response of elastic materials using large deformation continuum mechanics in three dimensions. This finite element formulation is based on the Eulerian description of motion and the transport of the deformation gradient. When modeling a nearly incompressible solid, the transport of the deformation gradient is decomposed into its isochoric part and the Jacobian determinant as independent fields. A homogeneous isotropic hyperelastic solid is assumed and B-splines-based finite elements are used for the spatial discretization. A variational multiscale residual-based approach is employed to stabilize the transport equations. The performance of the scheme is explored for both compressible and nearly incompressible applications. The numerical results are in good agreement with theory illustrating the viability of the computational scheme. © 2011 John Wiley & Sons, Ltd.

  3. Investigation of Dynamical Parameters of Exciton Confined in CdS Spherical Quantum Dots with a B-Spline Technique

    Institute of Scientific and Technical Information of China (English)

    HUI Ping; SHI Ting-Yun; BAO Cheng-Guang

    2003-01-01

    Exciton energies as a function of radii of quantum dots in the range of 5-35 A are calculated based on effective mass approximation model with the B-spline technique and compared with experimental and other theoretical data for the CdS dots. This method leads to accurate and fast convergent exciton energy, which are in good agreement with experimental data in the whole confinement regime. The effect of penetration of wave function from the inside to the outside of the dots and the effect of dielectric constants are taken into account. The magnitudes of dynamical parameters are discussed. It is found that the different materials surrounding the CdS quantum dot affect not only the potential energy and Coulomb interaction energy of the system, but also the effective masses. The comparison shows that the effective mass approximation model can describe very well the quantum size effects observed experimentally on the exciton ground state energy.

  4. Cutter Radius Compensation Method with B-spline Curves%B样条曲线刀具半径补偿方法

    Institute of Scientific and Technical Information of China (English)

    邓勇

    2001-01-01

    在数控激光切割加工中,由于作为刀具的激光焦点具有一定的半径,因而刀具中心轨迹并非零件实际轮廓,存在一个刀具半径补偿问题.为此提出了激光切割B样条曲线的一种刀具半径补偿方法.该方法利用常规等距曲线的数学模型及B样条曲线的端点性质,通过主动调整控制参数,获得精确的保形的等距曲线.其交点采用数值迭代求解,算法过程简单.%In computer numerical control(CNC) laser machining, because laser focus has radius,track of cutter is not practice contours of part,problem of cutter radius compensation is in existence. A method about B-spline curves cutter radius compensation is presented.It makes use of traditional mathematical model and character of end point of B-splines, regulates controlling parameter,so produces accurate B-spline offse curves.The intersection point of B-spline offset curves is solved by numerical iteration method.

  5. Correlation studies for B-spline modeled F2 Chapman parameters obtained from FORMOSAT-3/COSMIC data

    Science.gov (United States)

    Limberger, M.; Liang, W.; Schmidt, M.; Dettmering, D.; Hernández-Pajares, M.; Hugentobler, U.

    2014-12-01

    The determination of ionospheric key quantities such as the maximum electron density of the F2 layer NmF2, the corresponding F2 peak height hmF2 and the F2 scale height HF2 are of high relevance in 4-D ionosphere modeling to provide information on the vertical structure of the electron density (Ne). The Ne distribution with respect to height can, for instance, be modeled by the commonly accepted F2 Chapman layer. An adequate and observation driven description of the vertical Ne variation can be obtained from electron density profiles (EDPs) derived by ionospheric radio occultation measurements between GPS and low Earth orbiter (LEO) satellites. For these purposes, the six FORMOSAT-3/COSMIC (F3/C) satellites provide an excellent opportunity to collect EDPs that cover most of the ionospheric region, in particular the F2 layer. For the contents of this paper, F3/C EDPs have been exploited to determine NmF2, hmF2 and HF2 within a regional modeling approach. As mathematical base functions, endpoint-interpolating polynomial B-splines are considered to model the key parameters with respect to longitude, latitude and time. The description of deterministic processes and the verification of this modeling approach have been published previously in Limberger et al. (2013), whereas this paper should be considered as an extension dealing with related correlation studies, a topic to which less attention has been paid in the literature. Relations between the B-spline series coefficients regarding specific key parameters as well as dependencies between the three F2 Chapman key parameters are in the main focus. Dependencies are interpreted from the post-derived correlation matrices as a result of (1) a simulated scenario without data gaps by taking dense, homogenously distributed profiles into account and (2) two real data scenarios on 1 July 2008 and 1 July 2012 including sparsely, inhomogeneously distributed F3/C EDPs. Moderate correlations between hmF2 and HF2 as well as inverse

  6. Performance evaluation of block-diagonal preconditioners for the divergence-conforming B-spline discretization of the Stokes system

    KAUST Repository

    Côrtes, A.M.A.

    2015-02-20

    The recently introduced divergence-conforming B-spline discretizations allow the construction of smooth discrete velocity–pressure pairs for viscous incompressible flows that are at the same time inf-sup stable and pointwise divergence-free. When applied to discretized Stokes equations, these spaces generate a symmetric and indefinite saddle-point linear system. Krylov subspace methods are usually the most efficient procedures to solve such systems. One of such methods, for symmetric systems, is the Minimum Residual Method (MINRES). However, the efficiency and robustness of Krylov subspace methods is closely tied to appropriate preconditioning strategies. For the discrete Stokes system, in particular, block-diagonal strategies provide efficient preconditioners. In this article, we compare the performance of block-diagonal preconditioners for several block choices. We verify how the eigenvalue clustering promoted by the preconditioning strategies affects MINRES convergence. We also compare the number of iterations and wall-clock timings. We conclude that among the building blocks we tested, the strategy with relaxed inner conjugate gradients preconditioned with incomplete Cholesky provided the best results.

  7. Automatic optimal filament segmentation with sub-pixel accuracy using generalized linear models and B-spline level-sets.

    Science.gov (United States)

    Xiao, Xun; Geyer, Veikko F; Bowne-Anderson, Hugo; Howard, Jonathon; Sbalzarini, Ivo F

    2016-08-01

    Biological filaments, such as actin filaments, microtubules, and cilia, are often imaged using different light-microscopy techniques. Reconstructing the filament curve from the acquired images constitutes the filament segmentation problem. Since filaments have lower dimensionality than the image itself, there is an inherent trade-off between tracing the filament with sub-pixel accuracy and avoiding noise artifacts. Here, we present a globally optimal filament segmentation method based on B-spline vector level-sets and a generalized linear model for the pixel intensity statistics. We show that the resulting optimization problem is convex and can hence be solved with global optimality. We introduce a simple and efficient algorithm to compute such optimal filament segmentations, and provide an open-source implementation as an ImageJ/Fiji plugin. We further derive an information-theoretic lower bound on the filament segmentation error, quantifying how well an algorithm could possibly do given the information in the image. We show that our algorithm asymptotically reaches this bound in the spline coefficients. We validate our method in comprehensive benchmarks, compare with other methods, and show applications from fluorescence, phase-contrast, and dark-field microscopy. PMID:27104582

  8. Dynamic metabolic flux analysis using B-splines to study the effects of temperature shift on CHO cell metabolism

    Directory of Open Access Journals (Sweden)

    Verónica S. Martínez

    2015-12-01

    Full Text Available Metabolic flux analysis (MFA is widely used to estimate intracellular fluxes. Conventional MFA, however, is limited to continuous cultures and the mid-exponential growth phase of batch cultures. Dynamic MFA (DMFA has emerged to characterize time-resolved metabolic fluxes for the entire culture period. Here, the linear DMFA approach was extended using B-spline fitting (B-DMFA to estimate mass balanced fluxes. Smoother fits were achieved using reduced number of knots and parameters. Additionally, computation time was greatly reduced using a new heuristic algorithm for knot placement. B-DMFA revealed that Chinese hamster ovary cells shifted from 37 °C to 32 °C maintained a constant IgG volume-specific productivity, whereas the productivity for the controls peaked during mid-exponential growth phase and declined afterward. The observed 42% increase in product titer at 32 °C was explained by a prolonged cell growth with high cell viability, a larger cell volume and a more stable volume-specific productivity.

  9. Fast fluid registration of medical images

    DEFF Research Database (Denmark)

    Bro-Nielsen, Morten; Gramkow, Claus

    1996-01-01

    This paper offers a new fast algorithm for non-rigid viscous fluid registration of medical images that is at least an order of magnitude faster than the previous method by (Christensen et al., 1994). The core algorithm in the fluid registration method is based on a linear elastic deformation...

  10. Performance of global look-up table strategy in digital image correlation with cubic B-spline interpolation and bicubic interpolation

    Directory of Open Access Journals (Sweden)

    Zhiwei Pan

    2016-05-01

    Full Text Available Global look-up table strategy proposed recently has been proven to be an efficient method to accelerate the interpolation, which is the most time-consuming part in the iterative sub-pixel digital image correlation (DIC algorithms. In this paper, a global look-up table strategy with cubic B-spline interpolation is developed for the DIC method based on the inverse compositional Gauss–Newton (IC-GN algorithm. The performance of this strategy, including accuracy, precision, and computation efficiency, is evaluated through a theoretical and experimental study, using the one with widely employed bicubic interpolation as a benchmark. The global look-up table strategy with cubic B-spline interpolation improves significantly the accuracy of the IC-GN algorithm-based DIC method compared with the one using the bicubic interpolation, at a trivial price of computation efficiency.

  11. Seismic cross well tomography: a Gauss-Newton type algorithm based on B-Spline for velocity field parametrization. Part I: fundamentals

    Energy Technology Data Exchange (ETDEWEB)

    Soares Filho, Djalma Manoel; Eckhardt, Wietze; Braganca, Ricardo Silva Nunes de [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas. Setor de Geofisica e Estratigrafia

    1997-07-01

    A gauss-Newton type method for seismic crosswell traveltime tomography based on B-splines products linear combinations for velocity field representation is presented. Knot points and order are established through Dierckx approximation technique according to the initial guess model parameters. The Frechet derivatives are contour integrations along the rays and the regularization factor is estimated using the concepts of condition number and Backus-Gilbert spread factor for normalized resolution matrices. A numerical example demonstrates the robustness of the method. (author)

  12. Reverse engineering of complex biological body parts by squared distance enabled non-uniform rational B-spline technique and layered manufacturing.

    Science.gov (United States)

    Pandithevan, Ponnusamy

    2015-02-01

    In tissue engineering, the successful modeling of scaffold for the replacement of damaged body parts depends mainly on external geometry and internal architecture in order to avoid the adverse effects such as pain and lack of ability to transfer the load to the surrounding bone. Due to flexibility in controlling the parameters, layered manufacturing processes are widely used for the fabrication of bone tissue engineering scaffold with the given computer-aided design model. This article presents a squared distance minimization approach for weight optimization of non-uniform rational B-spline curve and surface to modify the geometry that exactly fits into the defect region automatically and thus to fabricate the scaffold specific to subject and site. The study showed that though the errors associated in the B-spline curve and surface were minimized by squared distance method than point distance method and tangent distance method, the errors could be minimized further in the rational B-spline curve and surface as the optimal weight could change the shape that desired for the defect site. In order to measure the efficacy of the present approach, the results were compared with point distance method and tangent distance method in optimizing the non-rational and rational B-spline curve and surface fitting for the defect site. The optimized geometry then allowed to construct the scaffold in fused deposition modeling system as an example. The result revealed that the squared distance-based weight optimization of the rational curve and surface in making the defect specific geometry best fits into the defect region than the other methods used.

  13. Detection of Thrips Defect on Green-Peel Citrus Using Hyperspectral Imaging Technology Combining PCA and B-Spline Lighting Correction Method

    Institute of Scientific and Technical Information of China (English)

    Dong Chun-wang; Ye Yang; Zhang Jian-qiang; Zhu hong-kai; Liu Fei

    2014-01-01

    In order to ifnd an effective method of detecting thrips defect on green-peel citrus, a defect segmentation method was developed using a single threshold value based on combination of characteristic wavelengths principal component analysis (PCA) and B-spline lighting correction method in this study. At ifrst, four characteristic wavelengths (523, 587, 700 and 768 nm) were obtained using PCA of Vis-NIR (visible and near-infrared) bands and analysis of weighting coefifcients;secondarily, PCA was performed using characteristic wavelengths and the second principal component (PC2) was selected to classify images;then, B-spline lighting correction method was proposed to overcome the inlfuence of lighting non-uniform on citrus when thrips defect was segmented;ifnally, thrips defect on citrus was extracted by global threshold segmentation and morphological image processing. The experimental results show that thrips defect in citrus can be detected with an accuracy of 96.5%by characteristic wavelengths PCA and B-spline lighting correction method. This study shows that thrips defect on green-peel citrus can be effectively identiifed using hyperspectral imaging technology.

  14. A Locally Modal B-Spline Based Full-Vector Finite-Element Method with PML for Nonlinear and Lossy Plasmonic Waveguide

    Science.gov (United States)

    Karimi, Hossein; Nikmehr, Saeid; Khodapanah, Ehsan

    2016-09-01

    In this paper, we develop a B-spline finite-element method (FEM) based on a locally modal wave propagation with anisotropic perfectly matched layers (PMLs), for the first time, to simulate nonlinear and lossy plasmonic waveguides. Conventional approaches like beam propagation method, inherently omit the wave spectrum and do not provide physical insight into nonlinear modes especially in the plasmonic applications, where nonlinear modes are constructed by linear modes with very close propagation constant quantities. Our locally modal B-spline finite element method (LMBS-FEM) does not suffer from the weakness of the conventional approaches. To validate our method, first, propagation of wave for various kinds of linear, nonlinear, lossless and lossy materials of metal-insulator plasmonic structures are simulated using LMBS-FEM in MATLAB and the comparisons are made with FEM-BPM module of COMSOL Multiphysics simulator and B-spline finite-element finite-difference wide angle beam propagation method (BSFEFD-WABPM). The comparisons show that not only our developed numerical approach is computationally more accurate and efficient than conventional approaches but also it provides physical insight into the nonlinear nature of the propagation modes.

  15. Multi-objective robust airfoil optimization based on non-uniform rational B-spline (NURBS) representation

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In order to improve airfoil performance under different flight conditions and to make the performance insensitive to off-design condition at the same time,a multi-objective optimization approach considering robust design has been developed and applied to airfoil design. Non-uniform rational B-spline (NURBS) representation is adopted in airfoil design process,control points and related weights around airfoil are used as design variables. Two airfoil representation cases show that the NURBS method can get airfoil geometry with max geometry error less than 0.0019. By using six-sigma robust approach in multi-objective airfoil design,each sub-objective function of the problem has robustness property. By adopting multi-objective genetic algorithm that is based on non-dominated sorting,a set of non-dominated airfoil solutions with robustness can be obtained in the design. The optimum robust airfoil can be traded off and selected in these non-dominated solutions by design tendency. By using the above methods,a multi-objective robust optimization was conducted for NASA SC0712 airfoil. After performing robust airfoil optimization,the mean value of drag coefficient at Ma0.7-0.8 and the mean value of lift coefficient at post stall regime (Ma0.3) have been improved by 12.2% and 25.4%. By comparing the aerodynamic force coefficients of optimization result,it shows that: different from single robust airfoil design which just improves the property of drag divergence at Ma0.7-0.8,multi-objective robust design can improve both the drag divergence property at Ma0.7-0.8 and stall property at low speed. The design cases show that the multi-objective robust design method makes the airfoil performance robust under different off-design conditions.

  16. Accuracy Validation for Medical Image Registration Algorithms: a Review

    Institute of Scientific and Technical Information of China (English)

    Zhe Liu; Xiang Deng; Guang-zhi Wang

    2012-01-01

    Accuracy validation is essential to clinical application of medical image registration techniques.Registration validation remains a challenging problem in practice mainly due to lack of 'ground truth'.In this paper,an overview of current validation methods for medical image registration is presented with detailed discussion of their benefits and drawbacks.Special focus is on non-rigid registration validation.Promising solution is also discussed.

  17. An Adaptive B-Spline Method for Low-order Image Reconstruction Problems - Final Report - 09/24/1997 - 09/24/2000

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xin; Miller, Eric L.; Rappaport, Carey; Silevich, Michael

    2000-04-11

    A common problem in signal processing is to estimate the structure of an object from noisy measurements linearly related to the desired image. These problems are broadly known as inverse problems. A key feature which complicates the solution to such problems is their ill-posedness. That is, small perturbations in the data arising e.g. from noise can and do lead to severe, non-physical artifacts in the recovered image. The process of stabilizing these problems is known as regularization of which Tikhonov regularization is one of the most common. While this approach leads to a simple linear least squares problem to solve for generating the reconstruction, it has the unfortunate side effect of producing smooth images thereby obscuring important features such as edges. Therefore, over the past decade there has been much work in the development of edge-preserving regularizers. This technique leads to image estimates in which the important features are retained, but computationally the y require the solution of a nonlinear least squares problem, a daunting task in many practical multi-dimensional applications. In this thesis we explore low-order models for reducing the complexity of the re-construction process. Specifically, B-Splines are used to approximate the object. If a ''proper'' collection B-Splines are chosen that the object can be efficiently represented using a few basis functions, the dimensionality of the underlying problem will be significantly decreased. Consequently, an optimum distribution of splines needs to be determined. Here, an adaptive refining and pruning algorithm is developed to solve the problem. The refining part is based on curvature information, in which the intuition is that a relatively dense set of fine scale basis elements should cluster near regions of high curvature while a spares collection of basis vectors are required to adequately represent the object over spatially smooth areas. The pruning part is a greedy

  18. Digital anthropomorphic phantoms of non-rigid human respiratory and voluntary body motion for investigating motion correction in emission imaging

    International Nuclear Information System (INIS)

    and body motion phantoms with a varying extent and character for each individual. In addition to these phantoms, we recorded the position of markers placed on the chest of the volunteers for the body motion studies, which could be used as external motion measurement. Using these phantoms and external motion data, investigators will be able to test their motion correction approaches for realistic motion obtained from different individuals. The non-uniform rational B-spline data and the parameter files for these phantoms are freely available for downloading and can be used with the XCAT license. (paper)

  19. RATIONAL QUADRATIC B-SPLINE INTERPOLATION OF FUNCTION SEGMENTS%函数的分段有理二次B样条插值

    Institute of Scientific and Technical Information of China (English)

    梁锡坤

    2012-01-01

    Based on the proper segmentation of complicated functions, the triangle convex hull of functions segment is introduced. We propose a scheme of control polygon determination by the tangent of the endpoints of the segment intervals. The algorithm of the segment rational quadratic B-spline interpolation of complicated functions is discussed in details. The interpolation keeps many important geometric features of the original function such as convexity, monotonicity and G1 continuity. The numerical experiments show that the algorithm provides an efficient approach to approximate representation of complicated functions.%0引 言 科学和工程计算中,函数的近似表示一直是一个重要课题.近似方法一般可归结为插值、逼近和拟合三种基本类型,经历长期发展,函数逼近方法[1-3]十分丰富.

  20. Modeling and animation of 3D characters with ball B-splines%基于球B样条的3D人物角色建模与动画

    Institute of Scientific and Technical Information of China (English)

    徐欣; 武仲科; 周明全; 骆岩林

    2009-01-01

    提出一种新的人物角色的快速建模和动画的方法.通过使用球B样条实现以骨架为基础自动构建角色模型以及数据驱动的角色动画生成方法.给定人物角色骨架后,依据人体测量学根据骨骼长度计算出关节点处的半径.通过插值关节点以及半径生成球B样条曲线曲面表示的角色模型.根据所获取的运动数据(来自运动捕获),通过更新控制顶点来更新角色模型,从而实现角色的实时动画.%This paper proposed a new approach for modeling and animation of characters. Through using ball B-splines, an automatic character building model based on skeleton was realized and a character animation generation method driven by data was obtained. When the skeleton of a character was given, these radii on joints were obtained according to the length of bones in anthropometry. Then ball B-spline curves and surfaces were generated to represent characters through interpolating joint points and radii on them. The modeling method is rapid. Furthermore, by using motion data to update control points, real-time animation is achieved.

  1. 基于B样条梯度的融合图像算法%Gradient Image Fusion Algorithm Based on B-Spline

    Institute of Scientific and Technical Information of China (English)

    刘军华; 雷超阳

    2012-01-01

    图像融合在目标识别、计算机视觉、医学、遥感图像处理等领域应用广泛.利用B样条梯度融合图像算法来解决图像融合,将融合的图像分成3×3予块,计算每个子块的B样务梯度.把待融合图像对应的子块梯度模值累加求和,计算每个子块梯度模值的权值并与每个子块相乘并求和,得到融合后的图像子块.模拟实验结果表明该方法是有效的,优于传统的主分量分析、小波变换和Laplacian金字塔等方法.%Image fusion is widely used in target recognition, computer vision, medicine, remote sensing, im- age processing and many other fields. This paper proposes an image fusion method based on B-spline gra- dient. It first divides the source image into small blocks of 3 × 3 size, calculates separately the B-spline gradient for each sub-block,adds up the gradient modulus values,calculates the weight value of each sub- block gradient modulus value,multiplies each sub-block and respective weight value and obtains the fu- sion image sub-block. Simulation experiments and analysis show that this method is effective and has a better performance than traditional methods such as principal component analysis, wavelet transforma- tion and the Laplacian pyramid.

  2. Application of Piecewise Cubic B-Spline%过两端点分段三次 B 样条方法应用研究*

    Institute of Scientific and Technical Information of China (English)

    王争争

    2015-01-01

    通过引入约束点 P0和常量 r,构建过两端点分段三次B样条曲线并推出衔接点光滑衔接条件。应用过两端点分段三次B样条方法可以构建直线、三角形、四边形及蛋形画法,并通过消齿光顺得到理想效果。实现图形的平移、缩放和旋转,通过逆时针、顺时针旋转计算消除偏差,保形效果理想。按顺时针方向生成闭曲线并记录轨迹点位置数据,方便平面上闭曲线对象间关系的计算,并得到布尔运算结果。应用该方法可以构建空间图形,实现颜色渐变效果理想。%By introducing the constraint point P0 and constant r ,two endpoints piecewise cubic B spline curve is built and some smooth cohesion terms are introduced .Application of two endpoints piecewise cubic B spline method can build straight lines ,triangles ,quadrilateral and egg painting .Through the elimination of tooth smoothing ,ideal effect is got . Translation ,scaling and rotation of graphics are achieved and eliminated by counterclockwise ,clockwise calculation devia‐tion ,conformal effect is ideal .Clockwise to generate closed curve trajectory point location and record data ,convenient plane closed curve calculation of relations between objects ,Boolean calculation results are obtained .The method can build space graphics ,make color gradient effect ideal .

  3. SU-E-J-109: Evaluation of Deformable Accumulated Parotid Doses Using Different Registration Algorithms in Adaptive Head and Neck Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Xu, S [Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education, Beijing, 100084 China (China); Chinese PLA General Hospital, Beijing, 100853 China (China); Liu, B [Image processing center, Beihang University, Beijing, 100191 China (China)

    2015-06-15

    Purpose: Three deformable image registration (DIR) algorithms are utilized to perform deformable dose accumulation for head and neck tomotherapy treatment, and the differences of the accumulated doses are evaluated. Methods: Daily MVCT data for 10 patients with pathologically proven nasopharyngeal cancers were analyzed. The data were acquired using tomotherapy (TomoTherapy, Accuray) at the PLA General Hospital. The prescription dose to the primary target was 70Gy in 33 fractions.Three DIR methods (B-spline, Diffeomorphic Demons and MIMvista) were used to propagate parotid structures from planning CTs to the daily CTs and accumulate fractionated dose on the planning CTs. The mean accumulated doses of parotids were quantitatively compared and the uncertainties of the propagated parotid contours were evaluated using Dice similarity index (DSI). Results: The planned mean dose of the ipsilateral parotids (32.42±3.13Gy) was slightly higher than those of the contralateral parotids (31.38±3.19Gy)in 10 patients. The difference between the accumulated mean doses of the ipsilateral parotids in the B-spline, Demons and MIMvista deformation algorithms (36.40±5.78Gy, 34.08±6.72Gy and 33.72±2.63Gy ) were statistically significant (B-spline vs Demons, P<0.0001, B-spline vs MIMvista, p =0.002). And The difference between those of the contralateral parotids in the B-spline, Demons and MIMvista deformation algorithms (34.08±4.82Gy, 32.42±4.80Gy and 33.92±4.65Gy ) were also significant (B-spline vs Demons, p =0.009, B-spline vs MIMvista, p =0.074). For the DSI analysis, the scores of B-spline, Demons and MIMvista DIRs were 0.90, 0.89 and 0.76. Conclusion: Shrinkage of parotid volumes results in the dose increase to the parotid glands in adaptive head and neck radiotherapy. The accumulated doses of parotids show significant difference using the different DIR algorithms between kVCT and MVCT. Therefore, the volume-based criterion (i.e. DSI) as a quantitative evaluation of

  4. Regional vertical total electron content (VTEC) modeling together with satellite and receiver differential code biases (DCBs) using semi-parametric multivariate adaptive regression B-splines (SP-BMARS)

    Science.gov (United States)

    Durmaz, Murat; Karslioglu, Mahmut Onur

    2015-04-01

    There are various global and regional methods that have been proposed for the modeling of ionospheric vertical total electron content (VTEC). Global distribution of VTEC is usually modeled by spherical harmonic expansions, while tensor products of compactly supported univariate B-splines can be used for regional modeling. In these empirical parametric models, the coefficients of the basis functions as well as differential code biases (DCBs) of satellites and receivers can be treated as unknown parameters which can be estimated from geometry-free linear combinations of global positioning system observables. In this work we propose a new semi-parametric multivariate adaptive regression B-splines (SP-BMARS) method for the regional modeling of VTEC together with satellite and receiver DCBs, where the parametric part of the model is related to the DCBs as fixed parameters and the non-parametric part adaptively models the spatio-temporal distribution of VTEC. The latter is based on multivariate adaptive regression B-splines which is a non-parametric modeling technique making use of compactly supported B-spline basis functions that are generated from the observations automatically. This algorithm takes advantage of an adaptive scale-by-scale model building strategy that searches for best-fitting B-splines to the data at each scale. The VTEC maps generated from the proposed method are compared numerically and visually with the global ionosphere maps (GIMs) which are provided by the Center for Orbit Determination in Europe (CODE). The VTEC values from SP-BMARS and CODE GIMs are also compared with VTEC values obtained through calibration using local ionospheric model. The estimated satellite and receiver DCBs from the SP-BMARS model are compared with the CODE distributed DCBs. The results show that the SP-BMARS algorithm can be used to estimate satellite and receiver DCBs while adaptively and flexibly modeling the daily regional VTEC.

  5. Efficient Constrained Local Model Fitting for Non-Rigid Face Alignment

    Science.gov (United States)

    Wang, Yang; Cox, Mark; Sridharan, Sridha; Cohn, Jeffery F.

    2009-01-01

    Active appearance models (AAMs) have demonstrated great utility when being employed for non-rigid face alignment/tracking. The “simultaneous” algorithm for fitting an AAM achieves good non-rigid face registration performance, but has poor real time performance (2-3 fps). The “project-out” algorithm for fitting an AAM achieves faster than real time performance (> 200 fps) but suffers from poor generic alignment performance. In this paper we introduce an extension to a discriminative method for non-rigid face registration/tracking referred to as a constrained local model (CLM). Our proposed method is able to achieve superior performance to the “simultaneous” AAM algorithm along with real time fitting speeds (35 fps). We improve upon the canonical CLM formulation, to gain this performance, in a number of ways by employing: (i) linear SVMs as patch-experts, (ii) a simplified optimization criteria, and (iii) a composite rather than additive warp update step. Most notably, our simplified optimization criteria for fitting the CLM divides the problem of finding a single complex registration/warp displacement into that of finding N simple warp displacements. From these N simple warp displacements, a single complex warp displacement is estimated using a weighted least-squares constraint. Another major advantage of this simplified optimization lends from its ability to be parallelized, a step which we also theoretically explore in this paper. We refer to our approach for fitting the CLM as the “exhaustive local search” (ELS) algorithm. Experiments were conducted on the CMU Multi-PIE database. PMID:20046797

  6. Efficient Constrained Local Model Fitting for Non-Rigid Face Alignment.

    Science.gov (United States)

    Lucey, Simon; Wang, Yang; Cox, Mark; Sridharan, Sridha; Cohn, Jeffery F

    2009-11-01

    Active appearance models (AAMs) have demonstrated great utility when being employed for non-rigid face alignment/tracking. The "simultaneous" algorithm for fitting an AAM achieves good non-rigid face registration performance, but has poor real time performance (2-3 fps). The "project-out" algorithm for fitting an AAM achieves faster than real time performance (> 200 fps) but suffers from poor generic alignment performance. In this paper we introduce an extension to a discriminative method for non-rigid face registration/tracking referred to as a constrained local model (CLM). Our proposed method is able to achieve superior performance to the "simultaneous" AAM algorithm along with real time fitting speeds (35 fps). We improve upon the canonical CLM formulation, to gain this performance, in a number of ways by employing: (i) linear SVMs as patch-experts, (ii) a simplified optimization criteria, and (iii) a composite rather than additive warp update step. Most notably, our simplified optimization criteria for fitting the CLM divides the problem of finding a single complex registration/warp displacement into that of finding N simple warp displacements. From these N simple warp displacements, a single complex warp displacement is estimated using a weighted least-squares constraint. Another major advantage of this simplified optimization lends from its ability to be parallelized, a step which we also theoretically explore in this paper. We refer to our approach for fitting the CLM as the "exhaustive local search" (ELS) algorithm. Experiments were conducted on the CMU Multi-PIE database. PMID:20046797

  7. Extracting a Purely Non-rigid Deformation Field of a Single Structure

    Science.gov (United States)

    Demirci, Stefanie; Manstad-Hulaas, Frode; Navab, Nassir

    During endovascular aortic repair (EVAR) treatment, the aortic shape is subject to severe deformation that is imposed by medical instruments such as guide wires, catheters, and the stent graft. The problem definition of deformable registration of images covering the entire abdominal region, however, is highly ill-posed. We present a new method for extracting the deformation of an aneurysmatic aorta. The outline of the procedure includes initial rigid alignment of two abdominal scans, segmentation of abdominal vessel trees, and automatic reduction of their centerline structures to one specified region of interest around the aorta. Our non-rigid registration procedure then only computes local non-rigid deformation and leaves out all remaining global rigid transformations. In order to evaluate our method, experiments for the extraction of aortic deformation fields are conducted on 15 patient datasets from endovascular aortic repair (EVAR) treatment. A visual assessment of the registration results were performed by two vascular surgeons and one interventional radiologist who are all experts in EVAR procedures.

  8. PET/CT成像呼吸运动B样条校正%Respiratory motion correction of PET/CT imaging based on B-spline

    Institute of Scientific and Technical Information of China (English)

    潘李鹏; 贺建峰; 封硕; 崔锐; 马磊; 相艳; 易三莉; 张俊

    2015-01-01

    The degradation of image quality of PET/CT caused by respiratory motion will affect the physician’s diagnosis. The common developed technology of respiratory motion correction is gating, but it still has some limitations. This paper proposes a new method that using CT images extract the features of respiratory motion based on B-Spline to correct respi-ration. Firstly, it obtains the sequence of CT images corresponding with PET images within same respiratory motion cycle, and extracts the features of the motion of CT sequences within respiratory cycle by B-Spline. Next it transforms the feature parameters of CT sequences into the corresponding PET image sequences for the motion correction. The geometric defor-mation phantom and voxelised phantom tests show that the proposed method can obviously improve the quality of image of PET/CT for respiratory motion, and has a value of study further.%PET/CT成像中的人体呼吸运动会造成图像运动模糊,会严重影响图像质量,对医生的诊断造成影响。目前常用的呼吸门控技术能够在一定程度上改善图像质量,但是均存在其局限性。提出了一种基于CT图像提取呼吸运动特征的B样条方法,对呼吸运动图像进行校正。在PET/CT上获取与PET图像周期匹配的CT图像序列,通过B样条配准方式对在呼吸周期内的CT图序列像提取运动信息;对CT图像所匹配的PET图像做基于运动特征信息的校正变换进行运动校正。几何位移形变和像素人体模实验结果表明,提出的方法对PET/CT呼吸运动图像质量改进明显,具有研究价值。

  9. Spectral Distance Distributions for Non-rigid Objects

    Institute of Scientific and Technical Information of China (English)

    CAO Wei-guo; LI Hai-yang; LI Shi-rui; LIU Yu-jie; LI Hua

    2013-01-01

    Non-rigid shape deformation without tearing or stretching is called isometry. There are many difficulties to research non-rigid shape in Euclidean space. Therefore, non-rigid shapes are firstly embedded into a none-Euclidean space. Spectral space is chosen in this paper. Then three descriptors are proposed based on three spectral distances. The existence of zero-eigenvalue has negative effects on computation of spectral distance. Therefore the spectral distance should be computed from the first non-zero-eigenvalue. Experiments show that spectral distance distributions are very effective to describe the non-rigid shapes.

  10. 基于三次B样条函数的SEM图像处理%SEM Image Processing Based on Third- order B- spline Function

    Institute of Scientific and Technical Information of China (English)

    张健

    2011-01-01

    SEM images, for its unique practical testing significance, need in denoising also highlight its edges and accurate edge extraction positioning, So this paper adopts a partial differential method which can maintain the edges of the denoising and a extensive application of multi - scale wavelet analysis to detect edges, all based on third - order B - spline function as the core operator, for line width test of SEM image processing, This algorithm obtained the better denoising effect and maintained edge features for SEM images.%SEM图像由于其独特的实际测试意义,需要在去噪的同时突出边缘和准确的边缘提取定位,所以提出采用能够保持边缘的偏微分方法去噪和广泛应用的多尺度小波提取边缘,基于三次B样条函数作为核心算子,对用于线宽测试的SEM图像进行处理,获得了较好的去噪并保持边缘的效果以及清晰的图像边缘检测效果.

  11. Una Técnica de Inteligencia Artificial para el Ajuste de uno de los Elementos que Definen una B-Spline Racional No Uniforme (NURBS A Technique of Artificial Intelligence to Fit one of the Elements that Define a Non-Uniform Rational B-Spline (NURBS

    Directory of Open Access Journals (Sweden)

    Sandra P Mateus

    2010-01-01

    Full Text Available Dentro de las técnicas existentes de Inteligencia Artificial, se escogieron y adaptaron dos Redes Neuronales Artificiales (RNA para realizar el ajuste de uno de los elementos que definen una B-Spline Racional No Uniforme (NURBS y con ello obtener un modelado adecuado de la NURBS. Los elementos escogidos fueron los puntos de control. Las RNA utilizadas son las de Función de Base Radial y las de Kohonen o Mapas Auto-organizativos. Con base en el análisis de resultados y la caracterización de las RNA, la Función de Base Radial tuvo un desempeño más adecuado y óptimo para un número elevado de datos, lo cual es una desventaja de los Mapas Auto-organizativos. En este modelo se tiene que realizar procesos extras para determinar la neurona ganadora y realizar el reajuste de los pesos.In the existing techniques of Artificial Intelligence, two Artificial Neural Networks (ANN were selected and adapted to fit one of the elements that define a Non-Uniform Rational B-Spline (NURBS and thus obtaining an appropriate modeling of the NURBS. The selected elements were the checkpoints. The ANN used were the Radial Basis Function and the Kohonen model or Self-Organizing Maps. Based on the analysis of the results and characterization of the ANN the Radial Basis Function had a more appropriate and optimum performance for a large number of data, which is a disadvantage of the Self-Organizing Maps. In this model, additional processes must be done to determine the winning neuron and the weights must be refitted.

  12. Symmetric and Transitive Registration of Image Sequences

    Directory of Open Access Journals (Sweden)

    Oskar Škrinjar

    2008-01-01

    Full Text Available This paper presents a method for constructing symmetric and transitive algorithms for registration of image sequences from image registration algorithms that do not have these two properties. The method is applicable to both rigid and nonrigid registration and it can be used with linear or periodic image sequences. The symmetry and transitivity properties are satisfied exactly (up to the machine precision, that is, they always hold regardless of the image type, quality, and the registration algorithm as long as the computed transformations are invertable. These two properties are especially important in motion tracking applications since physically incorrect deformations might be obtained if the registration algorithm is not symmetric and transitive. The method was tested on two sequences of cardiac magnetic resonance images using two different nonrigid image registration algorithms. It was demonstrated that the transitivity and symmetry errors of the symmetric and transitive modification of the algorithms could be made arbitrary small when the computed transformations are invertable, whereas the corresponding errors for the nonmodified algorithms were on the order of the pixel size. Furthermore, the symmetric and transitive modification of the algorithms had higher registration accuracy than the nonmodified algorithms for both image sequences.

  13. Infinitesimal nonrigidity of convex surfaces with planar boundary

    Institute of Scientific and Technical Information of China (English)

    LI Chunhe; HONG Jiaxing

    2005-01-01

    In the present paper infinitesimal nonrigidity of a class of convex surfaces with planar boundary is given. This result shows that if the image of the Gauss map of an evolution convex surface with planar boundary covers some hemisphere, this surface may be of infinitesimal nonrigidity for the isometric deformation of planar boundary.

  14. Myocardial motion estimation of tagged cardiac magnetic resonance images using tag motion constraints and multi-level b-splines interpolation.

    Science.gov (United States)

    Liu, Hong; Yan, Meng; Song, Enmin; Wang, Jie; Wang, Qian; Jin, Renchao; Jin, Lianghai; Hung, Chih-Cheng

    2016-05-01

    Myocardial motion estimation of tagged cardiac magnetic resonance (TCMR) images is of great significance in clinical diagnosis and the treatment of heart disease. Currently, the harmonic phase analysis method (HARP) and the local sine-wave modeling method (SinMod) have been proven as two state-of-the-art motion estimation methods for TCMR images, since they can directly obtain the inter-frame motion displacement vector field (MDVF) with high accuracy and fast speed. By comparison, SinMod has better performance over HARP in terms of displacement detection, noise and artifacts reduction. However, the SinMod method has some drawbacks: 1) it is unable to estimate local displacements larger than half of the tag spacing; 2) it has observable errors in tracking of tag motion; and 3) the estimated MDVF usually has large local errors. To overcome these problems, we present a novel motion estimation method in this study. The proposed method tracks the motion of tags and then estimates the dense MDVF by using the interpolation. In this new method, a parameter estimation procedure for global motion is applied to match tag intersections between different frames, ensuring specific kinds of large displacements being correctly estimated. In addition, a strategy of tag motion constraints is applied to eliminate most of errors produced by inter-frame tracking of tags and the multi-level b-splines approximation algorithm is utilized, so as to enhance the local continuity and accuracy of the final MDVF. In the estimation of the motion displacement, our proposed method can obtain a more accurate MDVF compared with the SinMod method and our method can overcome the drawbacks of the SinMod method. However, the motion estimation accuracy of our method depends on the accuracy of tag lines detection and our method has a higher time complexity. PMID:26712656

  15. The role of regularization in deformable image registration for head and neck adaptive radiotherapy.

    Science.gov (United States)

    Ciardo, D; Peroni, M; Riboldi, M; Alterio, D; Baroni, G; Orecchia, R

    2013-08-01

    Deformable image registration provides a robust mathematical framework to quantify morphological changes that occur along the course of external beam radiotherapy treatments. As clinical reliability of deformable image registration is not always guaranteed, algorithm regularization is commonly introduced to prevent sharp discontinuities in the quantified deformation and achieve anatomically consistent results. In this work we analyzed the influence of regularization on two different registration methods, i.e. B-Splines and Log Domain Diffeomorphic Demons, implemented in an open-source platform. We retrospectively analyzed the simulation computed tomography (CTsim) and the corresponding re-planning computed tomography (CTrepl) scans in 30 head and neck cancer patients. First, we investigated the influence of regularization levels on hounsfield units (HU) information in 10 test patients for each considered method. Then, we compared the registration results of the open-source implementation at selected best performing regularization levels with a clinical commercial software on the remaining 20 patients in terms of mean volume overlap, surface and center of mass distances between manual outlines and propagated structures. The regularized B-Splines method was not statistically different from the commercial software. The tuning of the regularization parameters allowed open-source algorithms to achieve better results in deformable image registration for head and neck patients, with the additional benefit of a framework where regularization can be tuned on a patient specific basis.

  16. TRIGONOMETRIC B-SPLINE CURVES AND SURFACES WITH SHAPE PARAMETER AND ITS APPLICATION%带形状参数三角B样条曲线曲面及其应用

    Institute of Scientific and Technical Information of China (English)

    陈素根; 汪志华; 赵正俊

    2015-01-01

    Aiming at the construction of spline curves and surfaces and its application in image zooming,we constructed in trigonometric function space {1,t ,sint ,cost ,sin2 t ,cos2 t }a kind of trigonometric B-spline basis function with shape parameter,and defined the corresponding trigonometric B-spline curves and surfaces,the properties of the trigonometric B-spline curves and surfaces and the effect of parameter in adjusting the shapes of curves and surfaces were also analysed.We broadened the value of shape parameter and constructed the trigonometric B-spline interpolation curves and surfaces which satisfy C2 continuity and can directly interpolate the given control vertices,and applied these interpolation surfaces to image zooming.Examples illustrated that the trigonometric B-spline curves and surfaces constructed in the paper had good application in curves and surfaces modelling and image zooming.%针对样条曲线曲面构造及其在图像放缩中的应用问题,在三角函数空间{1,t ,sint ,cost ,sin2 t ,cos2 t }中构造一类带有形状参数的三角 B 样条基函数,并定义相应的三角 B 样条曲线和曲面,分析该曲线曲面的性质以及形状参数对曲线曲面形状的调节作用。拓宽形状参数的取值,构造了满足 C2连续且可以直接插值控制顶点的三角 B 样条插值曲线和曲面,并将其应用于图像放缩中。实例说明了所构造的三角 B 样条曲线曲面在曲线曲面造型和图像放缩方面有较好应用。

  17. Mass preserving registration for heart MR images.

    Science.gov (United States)

    Zhu, Lei; Haker, Steven; Tannenbaum, Allen

    2005-01-01

    This paper presents a new algorithm for non-rigid registration between two doubly-connected regions. Our algorithm is based on harmonic analysis and the theory of optimal mass transport. It assumes an underlining continuum model, in which the total amount of mass is exactly preserved during the transformation of tissues. We use a finite element approach to numerically implement the algorithm. PMID:16685954

  18. Medical Image Registration and Surgery Simulation

    DEFF Research Database (Denmark)

    Bro-Nielsen, Morten

    1996-01-01

    This thesis explores the application of physical models in medical image registration and surgery simulation. The continuum models of elasticity and viscous fluids are described in detail, and this knowledge is used as a basis for most of the methods described here. Real-time deformable models......, and the use of selective matrix vector multiplication. Fluid medical image registration A new and faster algorithm for non-rigid registration using viscous fluid models is presented. This algorithm replaces the core part of the original algorithm with multi-resolution convolution using a new filter, which...... growth is also presented. Using medical knowledge about the growth processes of the mandibular bone, a registration algorithm for time sequence images of the mandible is developed. Since this registration algorithm models the actual development of the mandible, it is possible to simulate the development...

  19. Accurate tracking of tumor volume change during radiotherapy by CT-CBCT registration with intensity correction

    Science.gov (United States)

    Park, Seyoun; Robinson, Adam; Quon, Harry; Kiess, Ana P.; Shen, Colette; Wong, John; Plishker, William; Shekhar, Raj; Lee, Junghoon

    2016-03-01

    In this paper, we propose a CT-CBCT registration method to accurately predict the tumor volume change based on daily cone-beam CTs (CBCTs) during radiotherapy. CBCT is commonly used to reduce patient setup error during radiotherapy, but its poor image quality impedes accurate monitoring of anatomical changes. Although physician's contours drawn on the planning CT can be automatically propagated to daily CBCTs by deformable image registration (DIR), artifacts in CBCT often cause undesirable errors. To improve the accuracy of the registration-based segmentation, we developed a DIR method that iteratively corrects CBCT intensities by local histogram matching. Three popular DIR algorithms (B-spline, demons, and optical flow) with the intensity correction were implemented on a graphics processing unit for efficient computation. We evaluated their performances on six head and neck (HN) cancer cases. For each case, four trained scientists manually contoured the nodal gross tumor volume (GTV) on the planning CT and every other fraction CBCTs to which the propagated GTV contours by DIR were compared. The performance was also compared with commercial image registration software based on conventional mutual information (MI), VelocityAI (Varian Medical Systems Inc.). The volume differences (mean±std in cc) between the average of the manual segmentations and automatic segmentations are 3.70+/-2.30 (B-spline), 1.25+/-1.78 (demons), 0.93+/-1.14 (optical flow), and 4.39+/-3.86 (VelocityAI). The proposed method significantly reduced the estimation error by 9% (B-spline), 38% (demons), and 51% (optical flow) over the results using VelocityAI. Although demonstrated only on HN nodal GTVs, the results imply that the proposed method can produce improved segmentation of other critical structures over conventional methods.

  20. Image Edge Detection Based on B-spline Wavelet%基于B样条小波的图像边缘检测

    Institute of Scientific and Technical Information of China (English)

    周何; 黄山; 盛贤

    2011-01-01

    研究图像边缘优化检测问题.针对图像边缘信息被噪声污染影响定位精度,经典的边缘检测方法Canny算法中的高斯平滑函数边缘定位精确度较低,导致图像缓变边缘信息丢失和假边缘的现象.为去除虚假边缘,在Canny最优边缘检测准则下,提出引入了渐进最优的B样条小波函数,采用小波变换应用于图像边缘检测中的基于模极大值的方法,并结合Kmeans聚类的自适应双阈值方法进行图像边缘检测仿真.仿真结果表明,改进的算法改善了噪声干扰情况下图像边缘提取效果,有效提高了边缘检测的准确性,得到较高的边缘检测图像质量,可为设计提供依据.%In order to improve the low positioning accuracy of image edge detection, a research on optimization of image edge detection was carried out. The Gaussian smoothing function of the classical Canny edge detection method has lower edge positioning accuracy, which causes the missing of slowly varying edges and the producing of feigned edges and the edge detection is not accurate enough. So under the Canny criteria of optimum edge detection, the asymptotically optimal B-spline wavelet function was introduced. The method of modulus maxima of wavelet transform and the method of self-adapting dual threshold of kmeans clustering was used in the edge detection experiments. The experiments proved that the new algorithm is of higher accuracy and improves the quality of the edge detection images.

  1. A Variational Approach to Video Registration with Subspace Constraints

    OpenAIRE

    Garg, Ravi; Roussos, Anastasios; Agapito, Lourdes

    2013-01-01

    This paper addresses the problem of non-rigid video registration, or the computation of optical flow from a reference frame to each of the subsequent images in a sequence, when the camera views deformable objects. We exploit the high correlation between 2D trajectories of different points on the same non-rigid surface by assuming that the displacement of any point throughout the sequence can be expressed in a compact way as a linear combination of a low-rank motion basis. This subspace constr...

  2. Performance evaluation of 2D image registration algorithms with the numeric image registration and comparison platform

    International Nuclear Information System (INIS)

    The objective of this work is to present the capabilities of the NUMERICS web platform for evaluation of the performance of image registration algorithms. The NUMERICS platform is a web accessible tool which provides access to dedicated numerical algorithms for registration and comparison of medical images (http://numerics.phys.uni-sofia.bg). The platform allows comparison of noisy medical images by means of different types of image comparison algorithms, which are based on statistical tests for outliers. The platform also allows 2D image registration with different techniques like Elastic Thin-Plate Spline registration, registration based on rigid transformations, affine transformations, as well as non-rigid image registration based on Mobius transformations. In this work we demonstrate how the platform can be used as a tool for evaluation of the quality of the image registration process. We demonstrate performance evaluation of a deformable image registration technique based on Mobius transformations. The transformations are applied with appropriate cost functions like: Mutual information, Correlation coefficient, Sum of Squared Differences. The accent is on the results provided by the platform to the user and their interpretation in the context of the performance evaluation of 2D image registration. The NUMERICS image registration and image comparison platform provides detailed statistical information about submitted image registration jobs and can be used to perform quantitative evaluation of the performance of different image registration techniques. (authors)

  3. A MR-TRUS registration method for ultrasound-guided prostate interventions

    Science.gov (United States)

    Yang, Xiaofeng; Rossi, Peter; Mao, Hui; Jani, Ashesh B.; Ogunleye, Tomi; Curran, Walter J.; Liu, Tian

    2015-03-01

    In this paper, we reported a MR-TRUS prostate registration method that uses a subject-specific prostate strain model to improve MR-targeted, US-guided prostate interventions (e.g., biopsy and radiotherapy). The proposed algorithm combines a subject-specific prostate strain model with a Bspline transformation to register the prostate gland of the MRI to the TRUS images. The prostate strain model was obtained through US elastography and a 3D strain map of the prostate was generated. The B-spline transformation was calculated by minimizing Euclidean distance between MR and TRUS prostate surfaces. This prostate stain map was used to constrain the B-spline-based transformation to predict and compensate for the internal prostate-gland deformation. This method was validated with a prostate-phantom experiment and a pilot study of 5 prostate-cancer patients. For the phantom study, the mean target registration error (TRE) was 1.3 mm. MR-TRUS registration was also successfully performed for 5 patients with a mean TRE less than 2 mm. The proposed registration method may provide an accurate and robust means of estimating internal prostate-gland deformation, and could be valuable for prostate-cancer diagnosis and treatment.

  4. Global VTEC-modelling in near real-time based on space geodetic techniques, adapted B-spline expansions and Kalman-filtering including observations of the Sun's radiation

    Science.gov (United States)

    Börger, Klaus; Schmidt, Michael; Dettmering, Denise; Limberger, Marco; Erdogan, Eren; Seitz, Florian; Brandert, Sylvia; Görres, Barbara; Kersten, Wilhelm; Bothmer, Volker; Hinrichs, Johannes; Venzmer, Malte; Mrotzek, Niclas

    2016-04-01

    Today, the observations of space geodetic techniques are usually available with a rather low latency which applies to space missions observing the solar terrestrial environment, too. Therefore, we can use all these measurements in near real-time to compute and to provide ionosphere information, e.g. the vertical total electron content (VTEC). GSSAC and BGIC support a project aiming at a service for providing ionosphere information. This project is called OPTIMAP, meaning "Operational Tool for Ionosphere Mapping and Prediction"; the scientific work is mainly done by the German Geodetic Research Institute of the Technical University Munich (DGFI-TUM) and the Institute for Astrophysics of the University of Goettingen (IAG). The OPTIMAP strategy for providing ionosphere target quantities of high quality, such as VTEC or the electron density, includes mathematical approaches and tools allowing for the model adaptation to the real observational scenario as a significant improvement w.r.t. the traditional well-established methods. For example, OPTIMAP combines different observation types such as GNSS (GPS, GLONASS), Satellite Altimetry (Jason-2), DORIS as well as radio-occultation measurements (FORMOSAT#3/COSMIC). All these observations run into a Kalman-filter to compute global ionosphere maps, i.e. VTEC, for the current instant of time and as a forecast for a couple of subsequent days. Mathematically, the global VTEC is set up as a series expansion in terms of two-dimensional basis functions defined as tensor products of trigonometric B-splines for longitude and polynomial B-splines for latitude. Compared to the classical spherical harmonics, B-splines have a localizing character and, therefore, can handle an inhomogeneous data distribution properly. Finally, B-splines enable a so-called multi-resolution-representation (MRR) enabling the combination of global and regional modelling approaches. In addition to the geodetic measurements, Sun observations are pre

  5. Robust Corner Detection Based on Multi-scale Curvature Product in B-spline Scale Space%基于B样条尺度空间的鲁棒多尺度曲率积角点检测

    Institute of Scientific and Technical Information of China (English)

    王玉珠; 杨丹; 张小洪

    2007-01-01

    This paper presents a multi-scale curvature product corner detection technique in the framework of B-spline curvature scale space. A scale product function is derived from the curvature product of the contour at different scales. Corners are constructed as the local maxima by thresholding the curvature product results across several scales. Through scale product, the localization accuracy and detection performance can be notably improved in terms of CNN criteria. Experiments also demonstrate that proposed method shows robustness to high frequency details and provides promising detection results.

  6. A strategy for multimodal deformable image registration to integrate PET/MR into radiotherapy treatment planning

    Energy Technology Data Exchange (ETDEWEB)

    Leibfarth, Sara; Moennich, David; Thorwarth, Daniela [Section for Biomedical Physics, Dept. of Radiation Oncology, Univ. Hospital Tuebingen, Tuebingen (Germany)], e-mail: Sara.Leibfarth@med.uni-tuebingen.de; Welz, Stefan; Siegel, Christine; Zips, Daniel [Dept. of Radiation Oncology, Univ. Hospital Tuebingen, Tuebingen (Germany); Schwenzer, Nina [Dept. of Diagnostic and Interventional Radiology, Univ. Hospital Tuebingen, Tuebingen (Germany); Holger Schmidt, Holger [Dept. of Diagnostic and Interventional Radiology, Univ. Hospital Tuebingen, Tuebingen (Germany); Lab. for Preclinical Imaging and Imaging Technology of the Werner Siemens Foundation, Dept. of Preclinical Imaging and Radiopharmacy, Tuebingen (Germany)

    2013-10-15

    Background: Combined positron emission tomography (PET)/magnetic resonance imaging (MRI) is highly promising for biologically individualized radiotherapy (RT). Hence, the purpose of this work was to develop an accurate and robust registration strategy to integrate combined PET/MR data into RT treatment planning. Material and methods: Eight patient datasets consisting of an FDG PET/computed tomography (CT) and a subsequently acquired PET/MR of the head and neck (HN) region were available. Registration strategies were developed based on CT and MR data only, whereas the PET components were fused with the resulting deformation field. Following a rigid registration, deformable registration was performed with a transform parametrized by B-splines. Three different optimization metrics were investigated: global mutual information (GMI), GMI combined with a bending energy penalty (BEP) for regularization (GMI + BEP) and localized mutual information with BEP (LMI + BEP). Different quantitative registration quality measures were developed, including volumetric overlap and mean distance measures for structures segmented on CT and MR as well as anatomical landmark distances. Moreover, the local registration quality in the tumor region was assessed by the normalized cross correlation (NCC) of the two PET datasets. Results: LMI + BEP yielded the most robust and accurate registration results. For GMI, GMI + BEP and LMI + BEP, mean landmark distances (standard deviations) were 23.9 mm (15.5 mm), 4.8 mm (4.0 mm) and 3.0 mm (1.0 mm), and mean NCC values (standard deviations) were 0.29 (0.29), 0.84 (0.14) and 0.88 (0.06), respectively. Conclusion: Accurate and robust multimodal deformable image registration of CT and MR in the HN region can be performed using a B-spline parametrized transform and LMI + BEP as optimization metric. With this strategy, biologically individualized RT based on combined PET/MRI in terms of dose painting is possible.

  7. Estimación de la estructura a plazos de las tasas de interés en Colombia por medio del método de funciones B-spline cúbicas.

    Directory of Open Access Journals (Sweden)

    Diego Mauricio Vasquez E.

    2010-05-01

    Full Text Available En este documento se presenta la descripción y los resultados de la estimación de la estructura a plazos de las tasas de interés en Colombia utilizando el método de funciones B-spline cúbicas. Adicionalmente, se llevan a cabo comparaciones entre los resultados obtenidos a través de esta metodología y los presentados por Arango, Melo y Vásquez (2002 respecto a los métodos de Nelson y Siegel, y de la Bolsa de Valores de Colombia. Se observa que el desempeño del método de estimación de funciones Bspline cúbicas es similar al de Nelson y Siegel, y estos dos métodos superan al de la Bolsa de Valores de Colombia.

  8. Registration Service

    CERN Multimedia

    GS Department

    2010-01-01

    Following a reorganization in Building 55, please note that the Registration Service is now organised as follows :  Ground floor: access cards (76903). 1st floor : registration of external firms’ personnel (76611 / 76622); car access stickers (76633); biometric registration (79710). Opening hours: 07-30 to 16-00 non-stop. GS-SEM Group General Infrastructure Services Department

  9. Longitudinal brain MRI analysis with uncertain registration.

    Science.gov (United States)

    Simpson, Ivor J A; Woolrich, Mark W; Groves, Adrian R; Schnabel, Julia A

    2011-01-01

    In this paper we propose a novel approach for incorporating measures of spatial uncertainty, which are derived from non-rigid registration, into spatially normalised statistics. Current approaches to spatially normalised statistical analysis use point-estimates of the registration parameters. This is limiting as the registration will rarely be completely accurate, and therefore data smoothing is often used to compensate for the uncertainty of the mapping. We derive localised measurements of spatial uncertainty from a probabilistic registration framework, which provides a principled approach to image smoothing. We evaluate our method using longitudinal deformation features from a set of MR brain images acquired from the Alzheimer's Disease Neuroimaging Initiative. These images are spatially normalised using our probabilistic registration algorithm. The spatially normalised longitudinal features are adaptively smoothed according to the registration uncertainty. The proposed adaptive smoothing shows improved classification results, (84% correct Alzheimer's Disease vs. controls), over either not smoothing (79.6%), or using a Gaussian filter with sigma = 2mm (78.8%). PMID:21995084

  10. Motion Geometric Active Contours: Tracking Nonrigid Objects in Clutter Background

    Institute of Scientific and Technical Information of China (English)

    Cen Feng (岑峰); Qi Feihu

    2003-01-01

    MGAC (Motion Geometric Active Contours), a new variational framework of geometric active contours to track multiple nonrigid moving objects in the clutter background in image sequences is presented. This framework, incorporating with the motion edge information, consists of motion detection and tracking stages. At the motion detection stage, the motion edge map provides an approximate edge map of the moving objects. Then, a tracking stage, merely using the static edge information, is considered to improve the motion detection result. Force field regularization method is used to extend the capture range of the edge attraction force field in both stages. Experiments demonstrate that the proposed framework is valid for tracking multiple nonrigid objects in the clutter background.

  11. Cerebrovascular Expression Model Based on Ball B-Spline Curves and Tree Structure%球B样条曲线结合树状结构的脑血管表示模型

    Institute of Scientific and Technical Information of China (English)

    解立志; 周明全; 武仲科; 田沄

    2013-01-01

    针对分割之后的脑血管体数据场,提出基于球B样条曲线结合树状结构的表示模型.该模型中主要分为3个步骤表示脑血管:首先采用Hessian矩阵结合弹性球的方法获取脑血管的中心线和半径信息,可提高中心线的求取精度并且在中心线的求取过程中即可获得半径;然后对获得的中心线和半径进行树状重构,得到符合血管的形态拓扑结构,便于对脑血管进行遍历;最后对重构之后的每一分支血管采用球B样条曲线的方式来描述,以对脑血管病变区域进行检测,并能针对不同大小的显示窗口采用多尺度方式绘制.实验结果表明,文中模型在脑血管的显示、病灶检测等方面具有极大优势.%According to the cerebrovascular volume data after segmentation, the author proposes a cerebrovascular expression model based on ball B-spline curves and tree structure, which can be described as the following three steps. Firstly, we can get the centerline and radius of cerebral vessels according to a hessian matrix combined with elastic ball model, this improves the accuracy of center extraction and get radius simultaneously during the extraction process. Secondly, we deal with the centerline and radius got in the first step by tree reconstruction, because it accords with the topology of vascular and is easy to traverse. Finally, we describe every branch vessel by ball B-spline curves after reconstruction. This method of depiction can detect the lesion areas precisely and can draw the graph in multi-scale way to adapt to the display windows in different sizes. The experimental results show that this model has a great advantage in vessel display and cerebrovascular lesions detection.

  12. Nonrigid spherical real analytic hypersurfaces in C^2

    OpenAIRE

    Merker, Joel

    2009-01-01

    A Levi nondegenerate real analytic hypersurface M of C^2 represented in local coordinates (z, w) in C^2 by a complex defining equation of the form w = Theta (z, \\bar z, \\bar w) which satisfies an appropriate reality condition, is spherical if and only if its complex graphing function Theta satisfies an explicitly written sixth-order polynomial complex partial differential equation. In the rigid case (known before), this system simplifies considerably, but in the general nonrigid case, its com...

  13. Learning-Based Tracking of Complex Non-Rigid Motion

    Institute of Scientific and Technical Information of China (English)

    Qiang Wang; Hai-Zhou Ai; Guang-You Xu

    2004-01-01

    This paper describes a novel method for tracking complex non-rigid motions by learning the intrinsic object structure.The approach builds on and extends the studies on non-linear dimensionality reduction for object representation,object dynamics modeling and particle filter style tracking.First,the dimensionality reduction and density estimation algorithm is derived for unsupervised learning of object intrinsic representation,and the obtained non-rigid part of object state reduces even to 2-3 dimensions.Secondly the dynamical model is derived and trained based on this intrinsic representation.Thirdly the learned intrinsic object structure is integrated into a particle filter style tracker.It is shown that this intrinsic object representation has some interesting properties and based on which the newly derived dynamical model makes particle filter style tracker more robust and reliable.Extensive experiments are done on the tracking of challenging non-rigid motions such as fish twisting with selfocclusion,large inter-frame lip motion and facial expressions with global head rotation.Quantitative results are given to make comparisons between the newly proposed tracker and the existing tracker.The proposed method also has the potential to solve other type of tracking problems.

  14. Population-based prediction of subject-specific prostate deformation for MR-to-ultrasound image registration

    NARCIS (Netherlands)

    Hu, Y.; Gibson, E.D.G.; Ahmed, H.U.; Moore, C.M.; Emberton, M.; Barratt, D.C.

    2015-01-01

    Statistical shape models of soft-tissue organ motion provide a useful means of imposing physical constraints on the displacements allowed during non-rigid image registration, and can be especially useful when registering sparse and/or noisy image data. In this paper, we describe a method for generat

  15. A nonlinear biomechanical model based registration method for aligning prone and supine MR breast images.

    Science.gov (United States)

    Han, Lianghao; Hipwell, John H; Eiben, Björn; Barratt, Dean; Modat, Marc; Ourselin, Sebastien; Hawkes, David J

    2014-03-01

    Preoperative diagnostic magnetic resonance (MR) breast images can provide good contrast between different tissues and 3-D information about suspicious tissues. Aligning preoperative diagnostic MR images with a patient in the theatre during breast conserving surgery could assist surgeons in achieving the complete excision of cancer with sufficient margins. Typically, preoperative diagnostic MR breast images of a patient are obtained in the prone position, while surgery is performed in the supine position. The significant shape change of breasts between these two positions due to gravity loading, external forces and related constraints makes the alignment task extremely difficult. Our previous studies have shown that either nonrigid intensity-based image registration or biomechanical modelling alone are limited in their ability to capture such a large deformation. To tackle this problem, we proposed in this paper a nonlinear biomechanical model-based image registration method with a simultaneous optimization procedure for both the material parameters of breast tissues and the direction of the gravitational force. First, finite element (FE) based biomechanical modelling is used to estimate a physically plausible deformation of the pectoral muscle and the major deformation of breast tissues due to gravity loading. Then, nonrigid intensity-based image registration is employed to recover the remaining deformation that FE analyses do not capture due to the simplifications and approximations of biomechanical models and the uncertainties of external forces and constraints. We assess the registration performance of the proposed method using the target registration error of skin fiducial markers and the Dice similarity coefficient (DSC) of fibroglandular tissues. The registration results on prone and supine MR image pairs are compared with those from two alternative nonrigid registration methods for five breasts. Overall, the proposed algorithm achieved the best registration

  16. Evaluation of Interpolation Effects on Upsampling and Accuracy of Cost Functions-Based Optimized Automatic Image Registration

    Directory of Open Access Journals (Sweden)

    Amir Pasha Mahmoudzadeh

    2013-01-01

    Full Text Available Interpolation has become a default operation in image processing and medical imaging and is one of the important factors in the success of an intensity-based registration method. Interpolation is needed if the fractional unit of motion is not matched and located on the high resolution (HR grid. The purpose of this work is to present a systematic evaluation of eight standard interpolation techniques (trilinear, nearest neighbor, cubic Lagrangian, quintic Lagrangian, hepatic Lagrangian, windowed Sinc, B-spline 3rd order, and B-spline 4th order and to compare the effect of cost functions (least squares (LS, normalized mutual information (NMI, normalized cross correlation (NCC, and correlation ratio (CR for optimized automatic image registration (OAIR on 3D spoiled gradient recalled (SPGR magnetic resonance images (MRI of the brain acquired using a 3T GE MR scanner. Subsampling was performed in the axial, sagittal, and coronal directions to emulate three low resolution datasets. Afterwards, the low resolution datasets were upsampled using different interpolation methods, and they were then compared to the high resolution data. The mean squared error, peak signal to noise, joint entropy, and cost functions were computed for quantitative assessment of the method. Magnetic resonance image scans and joint histogram were used for qualitative assessment of the method.

  17. Accuracy and Utility of Deformable Image Registration in {sup 68}Ga 4D PET/CT Assessment of Pulmonary Perfusion Changes During and After Lung Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Hardcastle, Nicholas, E-mail: nick.hardcastle@gmail.com [Department of Physical Sciences, Peter MacCallum Cancer Centre, East Melbourne (Australia); Centre for Medical Radiation Physics, University of Wollongong, Wollongong (Australia); Hofman, Michael S. [Molecular Imaging, Centre for Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne (Australia); Hicks, Rodney J. [Molecular Imaging, Centre for Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne (Australia); Department of Medicine, University of Melbourne, Melbourne (Australia); Callahan, Jason [Molecular Imaging, Centre for Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne (Australia); Kron, Tomas [Department of Medical Imaging and Radiation Sciences, Monash University, Clayton (Australia); The Sir Peter MacCallum Department of Oncology, Melbourne University, Victoria (Australia); MacManus, Michael P.; Ball, David L. [Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, East Melbourne (Australia); The Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne (Australia); Jackson, Price [Department of Physical Sciences, Peter MacCallum Cancer Centre, East Melbourne (Australia); Siva, Shankar [Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, East Melbourne (Australia)

    2015-09-01

    Purpose: Measuring changes in lung perfusion resulting from radiation therapy dose requires registration of the functional imaging to the radiation therapy treatment planning scan. This study investigates registration accuracy and utility for positron emission tomography (PET)/computed tomography (CT) perfusion imaging in radiation therapy for non–small cell lung cancer. Methods: {sup 68}Ga 4-dimensional PET/CT ventilation-perfusion imaging was performed before, during, and after radiation therapy for 5 patients. Rigid registration and deformable image registration (DIR) using B-splines and Demons algorithms was performed with the CT data to obtain a deformation map between the functional images and planning CT. Contour propagation accuracy and correspondence of anatomic features were used to assess registration accuracy. Wilcoxon signed-rank test was used to determine statistical significance. Changes in lung perfusion resulting from radiation therapy dose were calculated for each registration method for each patient and averaged over all patients. Results: With B-splines/Demons DIR, median distance to agreement between lung contours reduced modestly by 0.9/1.1 mm, 1.3/1.6 mm, and 1.3/1.6 mm for pretreatment, midtreatment, and posttreatment (P<.01 for all), and median Dice score between lung contours improved by 0.04/0.04, 0.05/0.05, and 0.05/0.05 for pretreatment, midtreatment, and posttreatment (P<.001 for all). Distance between anatomic features reduced with DIR by median 2.5 mm and 2.8 for pretreatment and midtreatment time points, respectively (P=.001) and 1.4 mm for posttreatment (P>.2). Poorer posttreatment results were likely caused by posttreatment pneumonitis and tumor regression. Up to 80% standardized uptake value loss in perfusion scans was observed. There was limited change in the loss in lung perfusion between registration methods; however, Demons resulted in larger interpatient variation compared with rigid and B-splines registration

  18. Deformable Registration of Digital Images

    Institute of Scientific and Technical Information of China (English)

    管伟光; 解林; 等

    1998-01-01

    is paper proposes a novel elastic model and presents a deformable registration method based on the model.The method registers images without the need to extract reatures from the images,and therefore works directly on grey-level images.A new similarity metric is given on which the formation of external forces is based.The registration method,taking the coarse-to-fine strategy,constructs external forces in larger scales for the first few iterations to rely more on global evidence,and ther in smaller scales for later iterations to allow local refinements.The stiffness of the elastic body decreases as the process proceeds.To make it widely applicable,the method is not restricted to any type of transformation.The variations between images are thought as general free-form deformations.Because the elastic model designed is linearized,it can be solved very efficiently with high accuracy.The method has been successfully tested on MRI images.It will certainly find other uses such as matching time-varying sequences of pictures for motion analysis,fitting templates into images for non-rigid object recognition,matching stereo images for shape recovery,etc.

  19. Exact surface registration of retinal surfaces from 3-D optical coherence tomography images.

    Science.gov (United States)

    Lee, Sieun; Lebed, Evgeniy; Sarunic, Marinko V; Beg, Mirza Faisal

    2015-02-01

    Nonrigid registration of optical coherence tomography (OCT) images is an important problem in studying eye diseases, evaluating the effect of pharmaceuticals in treating vision loss, and performing group-wise cross-sectional analysis. High dimensional nonrigid registration algorithms required for cross-sectional and longitudinal analysis are still being developed for accurate registration of OCT image volumes, with the speckle noise in images presenting a challenge for registration. Development of algorithms for segmentation of OCT images to generate surface models of retinal layers has advanced considerably and several algorithms are now available that can segment retinal OCT images into constituent retinal surfaces. Important morphometric measurements can be extracted if accurate surface registration algorithm for registering retinal surfaces onto corresponding template surfaces were available. In this paper, we present a novel method to perform multiple and simultaneous retinal surface registration, targeted to registering surfaces extracted from ocular volumetric OCT images. This enables a point-to-point correspondence (homology) between template and subject surfaces, allowing for a direct, vertex-wise comparison of morphometric measurements across subject groups. We demonstrate that this approach can be used to localize and analyze regional changes in choroidal and nerve fiber layer thickness among healthy and glaucomatous subjects, allowing for cross-sectional population wise analysis. We also demonstrate the method's ability to track longitudinal changes in optic nerve head morphometry, allowing for within-individual tracking of morphometric changes. This method can also, in the future, be used as a precursor to 3-D OCT image registration to better initialize nonrigid image registration algorithms closer to the desired solution. PMID:25312906

  20. SU-E-J-94: Geometric and Dosimetric Evaluation of Deformation Image Registration Algorithms Using Virtual Phantoms Generated From Patients with Lung Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Z; Greskovich, J; Xia, P [The Cleveland Clinic, Cleveland, OH (United States); Bzdusek, K [Philips, Fitchburg, WI (United States)

    2015-06-15

    Purpose: To generate virtual phantoms with clinically relevant deformation and use them to objectively evaluate geometric and dosimetric uncertainties of deformable image registration (DIR) algorithms. Methods: Ten lung cancer patients undergoing adaptive 3DCRT planning were selected. For each patient, a pair of planning CT (pCT) and replanning CT (rCT) were used as the basis for virtual phantom generation. Manually adjusted meshes were created for selected ROIs (e.g. PTV, lungs, spinal cord, esophagus, and heart) on pCT and rCT. The mesh vertices were input into a thin-plate spline algorithm to generate a reference displacement vector field (DVF). The reference DVF was used to deform pCT to generate a simulated replanning CT (srCT) that was closely matched to rCT. Three DIR algorithms (Demons, B-Spline, and intensity-based) were applied to these ten virtual phantoms. The images, ROIs, and doses were mapped from pCT to srCT using the DVFs computed by these three DIRs and compared to those mapped using the reference DVF. Results: The average Dice coefficients for selected ROIs were from 0.85 to 0.96 for Demons, from 0.86 to 0.97 for intensity-based, and from 0.76 to 0.95 for B-Spline. The average Hausdorff distances for selected ROIs were from 2.2 to 5.4 mm for Demons, from 2.3 to 6.8 mm for intensity-based, and from 2.4 to 11.4 mm for B-Spline. The average absolute dose errors for selected ROIs were from 0.2 to 0.6 Gy for Demons, from 0.1 to 0.5 Gy for intensity-based, and from 0.5 to 1.5 Gy for B-Spline. Conclusion: Virtual phantoms were modeled after patients with lung cancer and were clinically relevant for adaptive radiotherapy treatment replanning. Virtual phantoms with known DVFs serve as references and can provide a fair comparison when evaluating different DIRs. Demons and intensity-based DIRs were shown to have smaller geometric and dosimetric uncertainties than B-Spline. Z Shen: None; K Bzdusek: an employee of Philips Healthcare; J Greskovich: None; P Xia

  1. SU-E-J-119: Head-And-Neck Digital Phantoms for Geometric and Dosimetric Uncertainty Evaluation of CT-CBCT Deformable Image Registration

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Z; Koyfman, S; Xia, P [The Cleveland Clinic, Cleveland, OH (United States); Bzdusek, K [Philips, Fitchburg, WI (United States)

    2015-06-15

    Purpose: To evaluate geometric and dosimetric uncertainties of CT-CBCT deformable image registration (DIR) algorithms using digital phantoms generated from real patients. Methods: We selected ten H&N cancer patients with adaptive IMRT. For each patient, a planning CT (CT1), a replanning CT (CT2), and a pretreatment CBCT (CBCT1) were used as the basis for digital phantom creation. Manually adjusted meshes were created for selected ROIs (e.g. PTVs, brainstem, spinal cord, mandible, and parotids) on CT1 and CT2. The mesh vertices were input into a thin-plate spline algorithm to generate a reference displacement vector field (DVF). The reference DVF was applied to CBCT1 to create a simulated mid-treatment CBCT (CBCT2). The CT-CBCT digital phantom consisted of CT1 and CBCT2, which were linked by the reference DVF. Three DIR algorithms (Demons, B-Spline, and intensity-based) were applied to these ten digital phantoms. The images, ROIs, and volumetric doses were mapped from CT1 to CBCT2 using the DVFs computed by these three DIRs and compared to those mapped using the reference DVF. Results: The average Dice coefficients for selected ROIs were from 0.83 to 0.94 for Demons, from 0.82 to 0.95 for B-Spline, and from 0.67 to 0.89 for intensity-based DIR. The average Hausdorff distances for selected ROIs were from 2.4 to 6.2 mm for Demons, from 1.8 to 5.9 mm for B-Spline, and from 2.8 to 11.2 mm for intensity-based DIR. The average absolute dose errors for selected ROIs were from 0.7 to 2.1 Gy for Demons, from 0.7 to 2.9 Gy for B- Spline, and from 1.3 to 4.5 Gy for intensity-based DIR. Conclusion: Using clinically realistic CT-CBCT digital phantoms, Demons and B-Spline were shown to have similar geometric and dosimetric uncertainties while intensity-based DIR had the worst uncertainties. CT-CBCT DIR has the potential to provide accurate CBCT-based dose verification for H&N adaptive radiotherapy. Z Shen: None; K Bzdusek: an employee of Philips Healthcare; S Koyfman: None; P Xia

  2. Non-Rigid Object Tracking by Anisotropic Kernel Mean Shift

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Mean shift, an iterative procedure that shifts each data point to the average of data points in its neighborhood, has been applied to object tracker. However, the traditional mean shift tracker by isotropic kernel often loses the object with the changing object structure in video sequences, especially when the object structure varies fast. This paper proposes a non-rigid object tracker by anisotropic kernel mean shift in which the shape, scale, and orientation of the kernels adapt to the changing object structure. The experimental results show that the new tracker is self-adaptive and approximately twice faster than the traditional tracker, which ensures the robustness and real time of tracking.

  3. Full Non-Rigid Group and Symmetry of Dimethyltrichlorophosphorus

    Institute of Scientific and Technical Information of China (English)

    ASHRAFI; AliReza

    2005-01-01

    In this work, a simple method is described, by means of which it is possible to calculate character tables for the symmetry group of molecules consisting of a number of NH3 groups attached to a rigid framework. The full non-rigid group (f-NRG) of dimethyltrichlorophosphorus with the symmetry group D3h was studied. It has been proven that it is a group of order 216 with 27 conjugacy classes and its character table computed. Finally, the Permutation-lnversion group of this molecule was calculated.

  4. Dynamic modeling and controller design for 3D output PDF based on 2D B-spline function%三维输出PDF动态线性建模与控制器设计

    Institute of Scientific and Technical Information of China (English)

    张金芳; 许曼

    2013-01-01

    文章对动态系统的三维输出概率密度函数(PDF)进行了线性建模和控制器设计研究。首先选择合适的二维 B 样条函数,利用系统的输入输出数据通过递归最小二乘算法建立了基于二维 B 样条函数的三维输出 PDF 的线性动态模型;然后根据所建立的数学模型,选择跟踪性能指标,进行了控制器的设计;最后,选择动态输出分布系统,进行了动态系统三维输出PDF控制的仿真研究,仿真结果证实了控制算法的有效性。%Dynamic modeling and controller design for the three dimensional (3D) output probability density function (PDF) are studied in this paper. Through recursive least square algorithm, the dynamic model of 3D PDF is set up based on two dimensional (2D) B-spline basis function with output and input data of the system firstly, then a tracking performance index is chosen to design a controller based 3D PDF dynamic model, at last a dynamic output distribution system is constructed for simulation study, and the results verify the effectiveness of the presented controller.

  5. A novel flexible framework with automatic feature correspondence optimization for nonrigid registration in radiotherapy

    NARCIS (Netherlands)

    E.M. Vásquez Osorio (Eliana); M.S. Hoogeman (Mischa); L. Bondar (Luiza); P.C. Levendag (Peter); B.J.M. Heijmen (Ben)

    2009-01-01

    textabstractTechnical improvements in planning and dose delivery and in verification of patient positioning have substantially widened the therapeutic window for radiation treatment of cancer. However, changes in patient anatomy during the treatment limit the exploitation of these new techniques. To

  6. Sequential Non-Rigid Structure from Motion Using Physical Priors.

    Science.gov (United States)

    Agudo, Antonio; Moreno-Noguer, Francesc; Calvo, Begona; Montiel, Jose M Martinez

    2016-05-01

    We propose a new approach to simultaneously recover camera pose and 3D shape of non-rigid and potentially extensible surfaces from a monocular image sequence. For this purpose, we make use of the Extended Kalman Filter based Simultaneous Localization And Mapping (EKF-SLAM) formulation, a Bayesian optimization framework traditionally used in mobile robotics for estimating camera pose and reconstructing rigid scenarios. In order to extend the problem to a deformable domain we represent the object's surface mechanics by means of Navier's equations, which are solved using a Finite Element Method (FEM). With these main ingredients, we can further model the material's stretching, allowing us to go a step further than most of current techniques, typically constrained to surfaces undergoing isometric deformations. We extensively validate our approach in both real and synthetic experiments, and demonstrate its advantages with respect to competing methods. More specifically, we show that besides simultaneously retrieving camera pose and non-rigid shape, our approach is adequate for both isometric and extensible surfaces, does not require neither batch processing all the frames nor tracking points over the whole sequence and runs at several frames per second. PMID:27046840

  7. Sequential Non-Rigid Structure from Motion Using Physical Priors.

    Science.gov (United States)

    Agudo, Antonio; Moreno-Noguer, Francesc; Calvo, Begona; Montiel, Jose M Martinez

    2016-05-01

    We propose a new approach to simultaneously recover camera pose and 3D shape of non-rigid and potentially extensible surfaces from a monocular image sequence. For this purpose, we make use of the Extended Kalman Filter based Simultaneous Localization And Mapping (EKF-SLAM) formulation, a Bayesian optimization framework traditionally used in mobile robotics for estimating camera pose and reconstructing rigid scenarios. In order to extend the problem to a deformable domain we represent the object's surface mechanics by means of Navier's equations, which are solved using a Finite Element Method (FEM). With these main ingredients, we can further model the material's stretching, allowing us to go a step further than most of current techniques, typically constrained to surfaces undergoing isometric deformations. We extensively validate our approach in both real and synthetic experiments, and demonstrate its advantages with respect to competing methods. More specifically, we show that besides simultaneously retrieving camera pose and non-rigid shape, our approach is adequate for both isometric and extensible surfaces, does not require neither batch processing all the frames nor tracking points over the whole sequence and runs at several frames per second.

  8. Higher Order Kernels and Locally Affine LDDMM Registration

    CERN Document Server

    Sommer, Stefan; Darkner, Sune; Pennec, Xavier

    2011-01-01

    To achieve sparse description that allows intuitive analysis, we aim to represent deformation with a basis containing interpretable elements, and we wish to use elements that have the description capacity to represent the deformation compactly. We accomplish this by introducing higher order kernels in the LDDMM registration framework. The kernels allow local description of affine transformations and subsequent compact description of non-translational movement and of the entire non-rigid deformation. This is obtained with a representation that contains directly interpretable information from both mathematical and modeling perspectives. We develop the mathematical construction behind the higher order kernels, we show the implications for sparse image registration and deformation description, and we provide examples of how the capacity of the kernels enables registration with a very low number of parameters. The capacity and interpretability of the kernels lead to natural modeling of articulated movement, and th...

  9. Testing for additivity with B-splines

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Regression splines are often used for fitting nonparametric functions, and they work especially well for additivity models. In this paper, we consider two simple tests of additivity: an adaptation of Tukey’s one degree of freedom test and a nonparametric version of Rao’s score test. While the Tukey-type test can detect most forms of the local non-additivity at the parametric rate of O(n-1/2), the score test is consistent for all alternative at a nonparametric rate. The asymptotic distribution of these test statistics is derived under both the null and local alternative hypotheses. A simulation study is conducted to compare their finite-sample performances with some existing kernel-based tests. The score test is found to have a good overall performance.

  10. Testing for additivity with B-splines

    Institute of Scientific and Technical Information of China (English)

    Heng-jian CUI; Xu-ming HE; Li LIU

    2007-01-01

    Regression splines are often used for fitting nonparametric functions, and they work especially well for additivity models. In this paper, we consider two simple tests of additivity: an adaptation of Tukey's one degree of freedom test and a nonparametric version of Rao's score test. While the Tukey-type test can detect most forms of the local non-additivity at the parametric rate of O(n-1/2), the score test is consistent for all alternative at a nonparametric rate. The asymptotic distribution of these test statistics is derived under both the null and local alternative hypotheses. A simulation study is conducted to compare their finite-sample performances with some existing kernelbased tests. The score test is found to have a good overall performance.

  11. 3D ultrasound-CT registration of the liver using combined landmark-intensity information

    International Nuclear Information System (INIS)

    An important issue in computer-assisted surgery of the liver is a fast and reliable transfer of preoperative resection plans to the intraoperative situation. One problem is to match the planning data, derived from preoperative CT or MR images, with 3D ultrasound images of the liver, acquired during surgery. As the liver deforms significantly in the intraoperative situation non-rigid registration is necessary. This is a particularly challenging task because pre- and intraoperative image data stem from different modalities and ultrasound images are generally very noisy. One way to overcome these problems is to incorporate prior knowledge into the registration process. We propose a method of combining anatomical landmark information with a fast non-parametric intensity registration approach. Mathematically, this leads to a constrained optimization problem. As distance measure we use the normalized gradient field which allows for multimodal image registration. A qualitative and quantitative validation on clinical liver data sets of three different patients has been performed. We used the distance of dense corresponding points on vessel center lines for quantitative validation. The combined landmark and intensity approach improves the mean and percentage of point distances above 3 mm compared to rigid and thin-plate spline registration based only on landmarks. The proposed algorithm offers the possibility to incorporate additional a priori knowledge - in terms of few landmarks - provided by a human expert into a non-rigid registration process. (orig.)

  12. Image registration

    CERN Document Server

    Goshtasby, A Ardeshir

    2012-01-01

    This book presents a thorough and detailed guide to image registration, outlining the principles and reviewing state-of-the-art tools and methods. The book begins by identifying the components of a general image registration system, and then describes the design of each component using various image analysis tools. The text reviews a vast array of tools and methods, not only describing the principles behind each tool and method, but also measuring and comparing their performances using synthetic and real data. Features: discusses similarity/dissimilarity measures, point detectors, feature extr

  13. Non-rigid connector in fixed partial dentures with pier abutment: An enigma simplified

    Directory of Open Access Journals (Sweden)

    Prince Kumar

    2012-01-01

    Full Text Available In the fixed partial denture (FPD prosthesis with rigid connectors, forces of mastication are transmitted to the terminal retainers, which make the middle abutment act as a class I lever fulcrum. This techno-clinical cycle often causes failure of the fixed partial dentures. To overcome this dilemma, a non-rigid connector may be incorporated on the distal aspect of the middle (pier abutment. The non-rigid connector counterbalances the effects of these forces of leverage. This clinical report presents the use of a non-rigid connector in a long-span, five-unit FPD, replacing two missing teeth with an intermediate pier abutment.

  14. Automatic Detection of Wild-type Mouse Cranial Sutures

    DEFF Research Database (Denmark)

    Ólafsdóttir, Hildur; Darvann, Tron Andre; Hermann, Nuno V.;

    , automatic detection of the cranial sutures becomes important. We have previously built a craniofacial, wild-type mouse atlas from a set of 10 Micro CT scans using a B-spline-based nonrigid registration method by Rueckert et al. Subsequently, all volumes were registered nonrigidly to the atlas. Using......, the observer traced the sutures on each of the mouse volumes as well. The observer outperforms the automatic approach by approximately 0.1 mm. All mice have similar errors while the suture error plots reveal that suture 1 and 2 are cumbersome, both for the observer and the automatic approach. These sutures can...

  15. Using patient-specific phantoms to evaluate deformable image registration algorithms for adaptive radiation therapy.

    Science.gov (United States)

    Stanley, Nick; Glide-Hurst, Carri; Kim, Jinkoo; Adams, Jeffrey; Li, Shunshan; Wen, Ning; Chetty, Indrin J; Zhong, Hualiang

    2013-11-04

    The quality of adaptive treatment planning depends on the accuracy of its underlying deformable image registration (DIR). The purpose of this study is to evaluate the performance of two DIR algorithms, B-spline-based deformable multipass (DMP) and deformable demons (Demons), implemented in a commercial software package. Evaluations were conducted using both computational and physical deformable phantoms. Based on a finite element method (FEM), a total of 11 computational models were developed from a set of CT images acquired from four lung and one prostate cancer patients. FEM generated displacement vector fields (DVF) were used to construct the lung and prostate image phantoms. Based on a fast-Fourier transform technique, image noise power spectrum was incorporated into the prostate image phantoms to create simulated CBCT images. The FEM-DVF served as a gold standard for verification of the two registration algorithms performed on these phantoms. The registration algorithms were also evaluated at the homologous points quantified in the CT images of a physical lung phantom. The results indicated that the mean errors of the DMP algorithm were in the range of 1.0 ~ 3.1 mm for the computational phantoms and 1.9 mm for the physical lung phantom. For the computational prostate phantoms, the corresponding mean error was 1.0-1.9 mm in the prostate, 1.9-2.4mm in the rectum, and 1.8-2.1 mm over the entire patient body. Sinusoidal errors induced by B-spline interpolations were observed in all the displacement profiles of the DMP registrations. Regions of large displacements were observed to have more registration errors. Patient-specific FEM models have been developed to evaluate the DIR algorithms implemented in the commercial software package. It has been found that the accuracy of these algorithms is patient dependent and related to various factors including tissue deformation magnitudes and image intensity gradients across the regions of interest. This may suggest that

  16. A batch Algorithm for Implicit Non-Rigid Shape and Motion Recovery

    DEFF Research Database (Denmark)

    Bartoli, Adrien; Olsen, Søren Ingvor

    2005-01-01

    The recovery of 3D shape and camera motion for non-rigid scenes from single-camera video footage is a very important problem in computer vision. The low-rank shape model consists in regarding the deformations as linear combinations of basis shapes. Most algorithms for reconstructing the parameters...... of this model along with camera motion are based on three main steps. Given point tracks and the rank, or equivalently the number of basis shapes, they factorize a measurement matrix containing all point tracks, from which the camera motion and basis shapes are extracted and refined in a bundle adjustment......-rigid scenes from which we derive non-rigid matching tensors and closure constraints. We give a non-rigid Structure-From-Motion algorithm based on computing matching tensors over subsequences, from which the implicit cameras are extrated. Each non-rigid matching tensor is computed, along with the rank...

  17. Mammogram CAD, hybrid registration and iconic analysis

    Science.gov (United States)

    Boucher, A.; Cloppet, F.; Vincent, N.

    2013-03-01

    This paper aims to develop a computer aided diagnosis (CAD) based on a two-step methodology to register and analyze pairs of temporal mammograms. The concept of "medical file", including all the previous medical information on a patient, enables joint analysis of different acquisitions taken at different times, and the detection of significant modifications. The developed registration method aims to superimpose at best the different anatomical structures of the breast. The registration is designed in order to get rid of deformation undergone by the acquisition process while preserving those due to breast changes indicative of malignancy. In order to reach this goal, a referent image is computed from control points based on anatomical features that are extracted automatically. Then the second image of the couple is realigned on the referent image, using a coarse-to-fine approach according to expert knowledge that allows both rigid and non-rigid transforms. The joint analysis detects the evolution between two images representing the same scene. In order to achieve this, it is important to know the registration error limits in order to adapt the observation scale. The approach used in this paper is based on an image sparse representation. Decomposed in regular patterns, the images are analyzed under a new angle. The evolution detection problem has many practical applications, especially in medical images. The CAD is evaluated using recall and precision of differences in mammograms.

  18. Non-rigid connector in fixed partial dentures with pier abutment: An enigma simplified

    OpenAIRE

    Prince Kumar; Vishal Singh; Roshni Goel; Harkanwal P Singh

    2012-01-01

    In the fixed partial denture (FPD) prosthesis with rigid connectors, forces of mastication are transmitted to the terminal retainers, which make the middle abutment act as a class I lever fulcrum. This techno-clinical cycle often causes failure of the fixed partial dentures. To overcome this dilemma, a non-rigid connector may be incorporated on the distal aspect of the middle (pier) abutment. The non-rigid connector counterbalances the effects of these forces of leverage. This clinical report...

  19. Elastic image registration via rigid object motion induced deformation

    Science.gov (United States)

    Zheng, Xiaofen; Udupa, Jayaram K.; Hirsch, Bruce E.

    2011-03-01

    In this paper, we estimate the deformations induced on soft tissues by the rigid independent movements of hard objects and create an admixture of rigid and elastic adaptive image registration transformations. By automatically segmenting and independently estimating the movement of rigid objects in 3D images, we can maintain rigidity in bones and hard tissues while appropriately deforming soft tissues. We tested our algorithms on 20 pairs of 3D MRI datasets pertaining to a kinematic study of the flexibility of the ankle complex of normal feet as well as ankles affected by abnormalities in foot architecture and ligament injuries. The results show that elastic image registration via rigid object-induced deformation outperforms purely rigid and purely nonrigid approaches.

  20. Automatic Mrf-Based Registration of High Resolution Satellite Video Data

    Science.gov (United States)

    Platias, C.; Vakalopoulou, M.; Karantzalos, K.

    2016-06-01

    In this paper we propose a deformable registration framework for high resolution satellite video data able to automatically and accurately co-register satellite video frames and/or register them to a reference map/image. The proposed approach performs non-rigid registration, formulates a Markov Random Fields (MRF) model, while efficient linear programming is employed for reaching the lowest potential of the cost function. The developed approach has been applied and validated on satellite video sequences from Skybox Imaging and compared with a rigid, descriptor-based registration method. Regarding the computational performance, both the MRF-based and the descriptor-based methods were quite efficient, with the first one converging in some minutes and the second in some seconds. Regarding the registration accuracy the proposed MRF-based method significantly outperformed the descriptor-based one in all the performing experiments.

  1. A Condition Number for Non-Rigid Shape Matching

    KAUST Repository

    Ovsjanikov, Maks

    2011-08-01

    © 2011 The Author(s). Despite the large amount of work devoted in recent years to the problem of non-rigid shape matching, practical methods that can successfully be used for arbitrary pairs of shapes remain elusive. In this paper, we study the hardness of the problem of shape matching, and introduce the notion of the shape condition number, which captures the intuition that some shapes are inherently more difficult to match against than others. In particular, we make a connection between the symmetry of a given shape and the stability of any method used to match it while optimizing a given distortion measure. We analyze two commonly used classes of methods in deformable shape matching, and show that the stability of both types of techniques can be captured by the appropriate notion of a condition number. We also provide a practical way to estimate the shape condition number and show how it can be used to guide the selection of landmark correspondences between shapes. Thus we shed some light on the reasons why general shape matching remains difficult and provide a way to detect and mitigate such difficulties in practice.

  2. Non-rigid alignment in electron tomography in materials science.

    Science.gov (United States)

    Printemps, Tony; Bernier, Nicolas; Bleuet, Pierre; Mula, Guido; Hervé, Lionel

    2016-09-01

    Electron tomography is a key technique that enables the visualization of an object in three dimensions with a resolution of about a nanometre. High-quality 3D reconstruction is possible thanks to the latest compressed sensing algorithms and/or better alignment and preprocessing of the 2D projections. Rigid alignment of 2D projections is routine in electron tomography. However, it cannot correct misalignments induced by (i) deformations of the sample due to radiation damage or (ii) drifting of the sample during the acquisition of an image in scanning transmission electron microscope mode. In both cases, those misalignments can give rise to artefacts in the reconstruction. We propose a simple-to-implement non-rigid alignment technique to correct those artefacts. This technique is particularly suited for needle-shaped samples in materials science. It is initiated by a rigid alignment of the projections and it is then followed by several rigid alignments of different parts of the projections. Piecewise linear deformations are applied to each projection to force them to simultaneously satisfy the rigid alignments of the different parts. The efficiency of this technique is demonstrated on three samples, an intermetallic sample with deformation misalignments due to a high electron dose typical to spectroscopic electron tomography, a porous silicon sample with an extremely thin end particularly sensitive to electron beam and another porous silicon sample that was drifting during image acquisitions.

  3. Efficient point cloud data processing in shipbuilding: Reformative component extraction method and registration method

    Directory of Open Access Journals (Sweden)

    Jingyu Sun

    2014-07-01

    Full Text Available To survive in the current shipbuilding industry, it is of vital importance for shipyards to have the ship components’ accuracy evaluated efficiently during most of the manufacturing steps. Evaluating components’ accuracy by comparing each component’s point cloud data scanned by laser scanners and the ship’s design data formatted in CAD cannot be processed efficiently when (1 extract components from point cloud data include irregular obstacles endogenously, or when (2 registration of the two data sets have no clear direction setting. This paper presents reformative point cloud data processing methods to solve these problems. K-d tree construction of the point cloud data fastens a neighbor searching of each point. Region growing method performed on the neighbor points of the seed point extracts the continuous part of the component, while curved surface fitting and B-spline curved line fitting at the edge of the continuous part recognize the neighbor domains of the same component divided by obstacles’ shadows. The ICP (Iterative Closest Point algorithm conducts a registration of the two sets of data after the proper registration’s direction is decided by principal component analysis. By experiments conducted at the shipyard, 200 curved shell plates are extracted from the scanned point cloud data, and registrations are conducted between them and the designed CAD data using the proposed methods for an accuracy evaluation. Results show that the methods proposed in this paper support the accuracy evaluation targeted point cloud data processing efficiently in practice.

  4. Implicit reference-based group-wise image registration and its application to structural and functional MRI.

    Science.gov (United States)

    Geng, Xiujuan; Christensen, Gary E; Gu, Hong; Ross, Thomas J; Yang, Yihong

    2009-10-01

    In this study, an implicit reference group-wise (IRG) registration with a small deformation, linear elastic model was used to jointly estimate correspondences between a set of MRI images. The performance of pair-wise and group-wise registration algorithms was evaluated for spatial normalization of structural and functional MRI data. Traditional spatial normalization is accomplished by group-to-reference (G2R) registration in which a group of images are registered pair-wise to a reference image. G2R registration is limited due to bias associated with selecting a reference image. In contrast, implicit reference group-wise (IRG) registration estimates correspondences between a group of images by jointly registering the images to an implicit reference corresponding to the group average. The implicit reference is estimated during IRG registration eliminating the bias associated with selecting a specific reference image. Registration performance was evaluated using segmented T1-weighted magnetic resonance images from the Nonrigid Image Registration Evaluation Project (NIREP), DTI and fMRI images. Implicit reference pair-wise (IRP) registration-a special case of IRG registration for two images-is shown to produce better relative overlap than IRG for pair-wise registration using the same small deformation, linear elastic registration model. However, IRP-G2R registration is shown to have significant transitivity error, i.e., significant inconsistencies between correspondences defined by different pair-wise transformations. In contrast, IRG registration produces consistent correspondence between images in a group at the cost of slightly reduced pair-wise RO accuracy compared to IRP-G2R. IRG spatial normalization of the fractional anisotropy (FA) maps of DTI is shown to have smaller FA variance compared with G2R methods using the same elastic registration model. Analyses of fMRI data sets with sensorimotor and visual tasks show that IRG registration, on average, increases the

  5. Deformable image registration for cone-beam CT guided transoral robotic base-of-tongue surgery

    International Nuclear Information System (INIS)

    Transoral robotic surgery (TORS) offers a minimally invasive approach to resection of base-of-tongue tumors. However, precise localization of the surgical target and adjacent critical structures can be challenged by the highly deformed intraoperative setup. We propose a deformable registration method using intraoperative cone-beam computed tomography (CBCT) to accurately align preoperative CT or MR images with the intraoperative scene. The registration method combines a Gaussian mixture (GM) model followed by a variation of the Demons algorithm. First, following segmentation of the volume of interest (i.e. volume of the tongue extending to the hyoid), a GM model is applied to surface point clouds for rigid initialization (GM rigid) followed by nonrigid deformation (GM nonrigid). Second, the registration is refined using the Demons algorithm applied to distance map transforms of the (GM-registered) preoperative image and intraoperative CBCT. Performance was evaluated in repeat cadaver studies (25 image pairs) in terms of target registration error (TRE), entropy correlation coefficient (ECC) and normalized pointwise mutual information (NPMI). Retraction of the tongue in the TORS operative setup induced gross deformation >30 mm. The mean TRE following the GM rigid, GM nonrigid and Demons steps was 4.6, 2.1 and 1.7 mm, respectively. The respective ECC was 0.57, 0.70 and 0.73, and NPMI was 0.46, 0.57 and 0.60. Registration accuracy was best across the superior aspect of the tongue and in proximity to the hyoid (by virtue of GM registration of surface points on these structures). The Demons step refined registration primarily in deeper portions of the tongue further from the surface and hyoid bone. Since the method does not use image intensities directly, it is suitable to multi-modality registration of preoperative CT or MR with intraoperative CBCT. Extending the 3D image registration to the fusion of image and planning data in stereo-endoscopic video is anticipated to

  6. Deformable image registration for cone-beam CT guided transoral robotic base-of-tongue surgery

    Science.gov (United States)

    Reaungamornrat, S.; Liu, W. P.; Wang, A. S.; Otake, Y.; Nithiananthan, S.; Uneri, A.; Schafer, S.; Tryggestad, E.; Richmon, J.; Sorger, J. M.; Siewerdsen, J. H.; Taylor, R. H.

    2013-07-01

    Transoral robotic surgery (TORS) offers a minimally invasive approach to resection of base-of-tongue tumors. However, precise localization of the surgical target and adjacent critical structures can be challenged by the highly deformed intraoperative setup. We propose a deformable registration method using intraoperative cone-beam computed tomography (CBCT) to accurately align preoperative CT or MR images with the intraoperative scene. The registration method combines a Gaussian mixture (GM) model followed by a variation of the Demons algorithm. First, following segmentation of the volume of interest (i.e. volume of the tongue extending to the hyoid), a GM model is applied to surface point clouds for rigid initialization (GM rigid) followed by nonrigid deformation (GM nonrigid). Second, the registration is refined using the Demons algorithm applied to distance map transforms of the (GM-registered) preoperative image and intraoperative CBCT. Performance was evaluated in repeat cadaver studies (25 image pairs) in terms of target registration error (TRE), entropy correlation coefficient (ECC) and normalized pointwise mutual information (NPMI). Retraction of the tongue in the TORS operative setup induced gross deformation >30 mm. The mean TRE following the GM rigid, GM nonrigid and Demons steps was 4.6, 2.1 and 1.7 mm, respectively. The respective ECC was 0.57, 0.70 and 0.73, and NPMI was 0.46, 0.57 and 0.60. Registration accuracy was best across the superior aspect of the tongue and in proximity to the hyoid (by virtue of GM registration of surface points on these structures). The Demons step refined registration primarily in deeper portions of the tongue further from the surface and hyoid bone. Since the method does not use image intensities directly, it is suitable to multi-modality registration of preoperative CT or MR with intraoperative CBCT. Extending the 3D image registration to the fusion of image and planning data in stereo-endoscopic video is anticipated to

  7. Estimation of 3D cardiac deformation using spatio-temporal elastic registration of non-scanconverted ultrasound data

    Science.gov (United States)

    Elen, An; Loeckx, Dirk; Choi, Hon Fai; Gao, Hang; Claus, Piet; Maes, Frederik; Suetens, Paul; D'hooge, Jan

    2008-03-01

    Current ultrasound methods for measuring myocardial strain are often limited to measurements in one or two dimensions. Spatio-temporal elastic registration of 3D cardiac ultrasound data can however be used to estimate the 3D motion and full 3D strain tensor. In this work, the spatio-temporal elastic registration method was validated for both non-scanconverted and scanconverted images. This was done using simulated 3D pyramidal ultrasound data sets based on a thick-walled deforming ellipsoid and an adapted convolution model. A B-spline based frame-to-frame elastic registration method was applied to both the scanconverted and non-scanconverded data sets and the accuracy of the resulting deformation fields was quantified. The mean accuracy of the estimated displacement was very similar for the scanconverted and non-scanconverted data sets and thus, it was shown that 3D elastic registration to estimate the cardiac deformation from ultrasound images can be performed on non-scanconverted images, but that avoiding of the scanconversion step does not significantly improve the results of the displacement estimation.

  8. Analysis and optimization of assembly variations for non-rigid parts

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Traditional variation analysis methods are not applicable to non-rigid assemblies due to possible part deformation during the assembly process. This paper presents the use of finite element methods to simulate assembly deformation. The relationship between the parts' variation and the variation of the key points in final assembly for quality control is set up by calculating the spring back deformation after assembly. Moreover, the optimization method for non-rigid assembly variations based on finite element analysis is presented. The optimal objective is to reduce the manufacturing cost. The approach is implemented by using ANSYS and MATLAB. The test example shows that the proposed method is effective and applicable.

  9. Real-time Animation Technique for a Kind of Non-rigid Objects

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A real-time animation technique for a kind of non-rigid objects, flexible and thin objects, is proposed, which can update with stability the state of n mass points of the mass-spring (MS) model with time complexity of O(n). The new implicit numerical integration technique of the authors, which is based on a simple approximation of the linear system, has great advantages over the existing implicit integration methods. Moreover, experiment shows that the new technique is highly efficient in animating a kind of non-rigid objects, and suitable for the draping module of the 3D garment CAD system.

  10. Kernel Bundle Diffeomorphic Image Registration Using Stationary Velocity Fields and Wendland Basis Functions.

    Science.gov (United States)

    Pai, Akshay; Sommer, Stefan; Sorensen, Lauge; Darkner, Sune; Sporring, Jon; Nielsen, Mads

    2016-06-01

    In this paper, we propose a multi-scale, multi-kernel shape, compactly supported kernel bundle framework for stationary velocity field-based image registration (Wendland kernel bundle stationary velocity field, wKB-SVF). We exploit the possibility of directly choosing kernels to construct a reproducing kernel Hilbert space (RKHS) instead of imposing it from a differential operator. The proposed framework allows us to minimize computational cost without sacrificing the theoretical foundations of SVF-based diffeomorphic registration. In order to recover deformations occurring at different scales, we use compactly supported Wendland kernels at multiple scales and orders to parameterize the velocity fields, and the framework allows simultaneous optimization over all scales. The performance of wKB-SVF is extensively compared to the 14 non-rigid registration algorithms presented in a recent comparison paper. On both MGH10 and CUMC12 datasets, the accuracy of wKB-SVF is improved when compared to other registration algorithms. In a disease-specific application for intra-subject registration, atrophy scores estimated using the proposed registration scheme separates the diagnostic groups of Alzheimer's and normal controls better than the state-of-the-art segmentation technique. Experimental results show that wKB-SVF is a robust, flexible registration framework that allows theoretically well-founded and computationally efficient multi-scale representation of deformations and is equally well-suited for both inter- and intra-subject image registration. PMID:26841388

  11. Mass Preserving Image Registration

    DEFF Research Database (Denmark)

    Gorbunova, V.; Sporring, J.; Lo, P.;

    2010-01-01

    The paper presents results the mass preserving image registration method in the Evaluation of Methods for Pulmonary Image Registration 2010 (EMPIRE10) Challenge. The mass preserving image registration algorithm was applied to the 20 image pairs. Registration was evaluated using four different...

  12. Deformable registration of multi-modal data including rigid structures

    Energy Technology Data Exchange (ETDEWEB)

    Huesman, Ronald H.; Klein, Gregory J.; Kimdon, Joey A.; Kuo, Chaincy; Majumdar, Sharmila

    2003-05-02

    Multi-modality imaging studies are becoming more widely utilized in the analysis of medical data. Anatomical data from CT and MRI are useful for analyzing or further processing functional data from techniques such as PET and SPECT. When data are not acquired simultaneously, even when these data are acquired on a dual-imaging device using the same bed, motion can occur that requires registration between the reconstructed image volumes. As the human torso can allow non-rigid motion, this type of motion should be estimated and corrected. We report a deformation registration technique that utilizes rigid registration for bony structures, while allowing elastic transformation of soft tissue to more accurately register the entire image volume. The technique is applied to the registration of CT and MR images of the lumbar spine. First a global rigid registration is performed to approximately align features. Bony structures are then segmented from the CT data using semi-automated process, and bounding boxes for each vertebra are established. Each CT subvolume is then individually registered to the MRI data using a piece-wise rigid registration algorithm and a mutual information image similarity measure. The resulting set of rigid transformations allows for accurate registration of the parts of the CT and MRI data representing the vertebrae, but not the adjacent soft tissue. To align the soft tissue, a smoothly-varying deformation is computed using a thin platespline(TPS) algorithm. The TPS technique requires a sparse set of landmarks that are to be brought into correspondence. These landmarks are automatically obtained from the segmented data using simple edge-detection techniques and random sampling from the edge candidates. A smoothness parameter is also included in the TPS formulation for characterization of the stiffness of the soft tissue. Estimation of an appropriate stiffness factor is obtained iteratively by using the mutual information cost function on the result

  13. Deformable mesh registration for the validation of automatic target localization algorithms

    Science.gov (United States)

    Robertson, Scott; Weiss, Elisabeth; Hugo, Geoffrey D.

    2013-01-01

    Purpose: To evaluate deformable mesh registration (DMR) as a tool for validating automatic target registration algorithms used during image-guided radiation therapy. Methods: DMR was implemented in a hierarchical model, with rigid, affine, and B-spline transforms optimized in succession to register a pair of surface meshes. The gross tumor volumes (primary tumor and involved lymph nodes) were contoured by a physician on weekly CT scans in a cohort of lung cancer patients and converted to surface meshes. The meshes from weekly CT images were registered to the mesh from the planning CT, and the resulting registered meshes were compared with the delineated surfaces. Known deformations were also applied to the meshes, followed by mesh registration to recover the known deformation. Mesh registration accuracy was assessed at the mesh surface by computing the symmetric surface distance (SSD) between vertices of each registered mesh pair. Mesh registration quality in regions within 5 mm of the mesh surface was evaluated with respect to a high quality deformable image registration. Results: For 18 patients presenting with a total of 19 primary lung tumors and 24 lymph node targets, the SSD averaged 1.3 ± 0.5 and 0.8 ± 0.2 mm, respectively. Vertex registration errors (VRE) relative to the applied known deformation were 0.8 ± 0.7 and 0.2 ± 0.3 mm for the primary tumor and lymph nodes, respectively. Inside the mesh surface, corresponding average VRE ranged from 0.6 to 0.9 and 0.2 to 0.9 mm, respectively. Outside the mesh surface, average VRE ranged from 0.7 to 1.8 and 0.2 to 1.4 mm. The magnitude of errors generally increased with increasing distance away from the mesh. Conclusions: Provided that delineated surfaces are available, deformable mesh registration is an accurate and reliable method for obtaining a reference registration to validate automatic target registration algorithms for image-guided radiation therapy, specifically in regions on or near the target surfaces

  14. TU-F-BRF-02: MR-US Prostate Registration Using Patient-Specific Tissue Elasticity Property Prior for MR-Targeted, TRUS-Guided HDR Brachytherapy

    International Nuclear Information System (INIS)

    Purpose: High-dose-rate (HDR) brachytherapy has become a popular treatment modality for prostate cancer. Conventional transrectal ultrasound (TRUS)-guided prostate HDR brachytherapy could benefit significantly from MR-targeted, TRUS-guided procedure where the tumor locations, acquired from the multiparametric MRI, are incorporated into the treatment planning. In order to enable this integration, we have developed a MR-TRUS registration with a patient-specific biomechanical elasticity prior. Methods: The proposed method used a biomechanical elasticity prior to guide the prostate volumetric B-spline deformation in the MRI and TRUS registration. The patient-specific biomechanical elasticity prior was generated using ultrasound elastography, where two 3D TRUS prostate images were acquired under different probe-induced pressures during the HDR procedure, which takes 2-4 minutes. These two 3D TRUS images were used to calculate the local displacement (elasticity map) of two prostate volumes. The B-spline transformation was calculated by minimizing the Euclidean distance between the normalized attribute vectors of the prostate surface landmarks on the MR and TRUS. This technique was evaluated through two studies: a prostate-phantom study and a pilot study with 5 patients undergoing prostate HDR treatment. The accuracy of our approach was assessed through the locations of several landmarks in the post-registration and TRUS images; our registration results were compared with the surface-based method. Results: For the phantom study, the mean landmark displacement of the proposed method was 1.29±0.11 mm. For the 5 patients, the mean landmark displacement of the surface-based method was 3.25±0.51 mm; our method, 1.71±0.25 mm. Therefore, our proposed method of prostate registration outperformed the surfaced-based registration significantly. Conclusion: We have developed a novel MR-TRUS prostate registration approach based on patient-specific biomechanical elasticity prior

  15. Active zone impact on deformation state of non-rigid pavement

    Science.gov (United States)

    Mandula, Ján

    2014-06-01

    The paper deals with the design of non-rigid pavement, with emphasis on the effect of active zone on its deformation state. The concepts of determination of active zone are described. The results of numerical modelling of pavement laying on elastic subgrade are presented in the paper

  16. Active zone impact on deformation state of non-rigid pavement

    Directory of Open Access Journals (Sweden)

    Mandula Ján

    2014-06-01

    Full Text Available The paper deals with the design of non-rigid pavement, with emphasis on the effect of active zone on its deformation state. The concepts of determination of active zone are described. The results of numerical modelling of pavement laying on elastic subgrade are presented in the paper

  17. Improving Intensity-Based Lung CT Registration Accuracy Utilizing Vascular Information

    Directory of Open Access Journals (Sweden)

    Kunlin Cao

    2012-01-01

    Full Text Available Accurate pulmonary image registration is a challenging problem when the lungs have a deformation with large distance. In this work, we present a nonrigid volumetric registration algorithm to track lung motion between a pair of intrasubject CT images acquired at different inflation levels and introduce a new vesselness similarity cost that improves intensity-only registration. Volumetric CT datasets from six human subjects were used in this study. The performance of four intensity-only registration algorithms was compared with and without adding the vesselness similarity cost function. Matching accuracy was evaluated using landmarks, vessel tree, and fissure planes. The Jacobian determinant of the transformation was used to reveal the deformation pattern of local parenchymal tissue. The average matching error for intensity-only registration methods was on the order of 1 mm at landmarks and 1.5 mm on fissure planes. After adding the vesselness preserving cost function, the landmark and fissure positioning errors decreased approximately by 25% and 30%, respectively. The vesselness cost function effectively helped improve the registration accuracy in regions near thoracic cage and near the diaphragm for all the intensity-only registration algorithms tested and also helped produce more consistent and more reliable patterns of regional tissue deformation.

  18. A quantitative comparison of the performance of three deformable registration algorithms in radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Fabri, Daniella; Bhatia, Amon [Medical Univ. of Vienna (Austria). Center of Medical Physics and Biomedical Engineering; Zambrano, Valentina [Medical Univ. of Vienna (Austria). Dept. of Radiotherapy; and others

    2013-07-01

    We present an evaluation of various non-rigid registration algorithms for the purpose of compensating interfractional motion of the target volume and organs at risk areas when acquiring CBCT image data prior to irradiation. Three different deformable registration (DR) methods were used: the Demons algorithm implemented in the iPlan Software (BrainLAB AG, Feldkirchen, Germany) and two custom-developed piecewise methods using either a Normalized Correlation or a Mutual Information metric (featurelet{sub NC} and featurelet{sub MI}). These methods were tested on data acquired using a novel purpose-built phantom for deformable registration and clinical CT/CBCT data of prostate and lung cancer patients. The Dice similarity coefficient (DSC) between manually drawn contours and the contours generated by a derived deformation field of the structures in question was compared to the result obtained with rigid registration (RR). For the phantom, the piecewise methods were slightly superior, the featurelet{sub NC} for the intramodality and the featurelet{sub MI} for the intermodality registrations. For the prostate cases in less than 50% of the images studied the DSC was improved over RR. Deformable registration methods improved the outcome over a rigid registration for lung cases and in the phantom study, but not in a significant way for the prostate study. A significantly superior deformation method could not be identified. (orig.)

  19. Evaluation of Deformable Image Registration Methods for Dose Monitoring in Head and Neck Radiotherapy

    Directory of Open Access Journals (Sweden)

    Bastien Rigaud

    2015-01-01

    Full Text Available In the context of head and neck cancer (HNC adaptive radiation therapy (ART, the two purposes of the study were to compare the performance of multiple deformable image registration (DIR methods and to quantify their impact for dose accumulation, in healthy structures. Fifteen HNC patients had a planning computed tomography (CT0 and weekly CTs during the 7 weeks of intensity-modulated radiation therapy (IMRT. Ten DIR approaches using different registration methods (demons or B-spline free form deformation (FFD, preprocessing, and similarity metrics were tested. Two observers identified 14 landmarks (LM on each CT-scan to compute LM registration error. The cumulated doses estimated by each method were compared. The two most effective DIR methods were the demons and the FFD, with both the mutual information (MI metric and the filtered CTs. The corresponding LM registration accuracy (precision was 2.44 mm (1.30 mm and 2.54 mm (1.33 mm, respectively. The corresponding LM estimated cumulated dose accuracy (dose precision was 0.85 Gy (0.93 Gy and 0.88 Gy (0.95 Gy, respectively. The mean uncertainty (difference between maximal and minimal dose considering all the 10 methods to estimate the cumulated mean dose to the parotid gland (PG was 4.03 Gy (SD = 2.27 Gy, range: 1.06–8.91 Gy.

  20. Automated analysis of small animal PET studies through deformable registration to an atlas

    International Nuclear Information System (INIS)

    This work aims to develop a methodology for automated atlas-guided analysis of small animal positron emission tomography (PET) data through deformable registration to an anatomical mouse model. A non-rigid registration technique is used to put into correspondence relevant anatomical regions of rodent CT images from combined PET/CT studies to corresponding CT images of the Digimouse anatomical mouse model. The latter provides a pre-segmented atlas consisting of 21 anatomical regions suitable for automated quantitative analysis. Image registration is performed using a package based on the Insight Toolkit allowing the implementation of various image registration algorithms. The optimal parameters obtained for deformable registration were applied to simulated and experimental mouse PET/CT studies. The accuracy of the image registration procedure was assessed by segmenting mouse CT images into seven regions: brain, lungs, heart, kidneys, bladder, skeleton and the rest of the body. This was accomplished prior to image registration using a semi-automated algorithm. Each mouse segmentation was transformed using the parameters obtained during CT to CT image registration. The resulting segmentation was compared with the original Digimouse atlas to quantify image registration accuracy using established metrics such as the Dice coefficient and Hausdorff distance. PET images were then transformed using the same technique and automated quantitative analysis of tracer uptake performed. The Dice coefficient and Hausdorff distance show fair to excellent agreement and a mean registration mismatch distance of about 6 mm. The results demonstrate good quantification accuracy in most of the regions, especially the brain, but not in the bladder, as expected. Normalized mean activity estimates were preserved between the reference and automated quantification techniques with relative errors below 10 % in most of the organs considered. The proposed automated quantification technique is

  1. Automated analysis of small animal PET studies through deformable registration to an atlas

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez, Daniel F. [Geneva University Hospital, Division of Nuclear Medicine and Molecular Imaging, Geneva 4 (Switzerland); Zaidi, Habib [Geneva University Hospital, Division of Nuclear Medicine and Molecular Imaging, Geneva 4 (Switzerland); Geneva University, Geneva Neuroscience Center, Geneva (Switzerland); University of Groningen, Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, Groningen (Netherlands)

    2012-11-15

    This work aims to develop a methodology for automated atlas-guided analysis of small animal positron emission tomography (PET) data through deformable registration to an anatomical mouse model. A non-rigid registration technique is used to put into correspondence relevant anatomical regions of rodent CT images from combined PET/CT studies to corresponding CT images of the Digimouse anatomical mouse model. The latter provides a pre-segmented atlas consisting of 21 anatomical regions suitable for automated quantitative analysis. Image registration is performed using a package based on the Insight Toolkit allowing the implementation of various image registration algorithms. The optimal parameters obtained for deformable registration were applied to simulated and experimental mouse PET/CT studies. The accuracy of the image registration procedure was assessed by segmenting mouse CT images into seven regions: brain, lungs, heart, kidneys, bladder, skeleton and the rest of the body. This was accomplished prior to image registration using a semi-automated algorithm. Each mouse segmentation was transformed using the parameters obtained during CT to CT image registration. The resulting segmentation was compared with the original Digimouse atlas to quantify image registration accuracy using established metrics such as the Dice coefficient and Hausdorff distance. PET images were then transformed using the same technique and automated quantitative analysis of tracer uptake performed. The Dice coefficient and Hausdorff distance show fair to excellent agreement and a mean registration mismatch distance of about 6 mm. The results demonstrate good quantification accuracy in most of the regions, especially the brain, but not in the bladder, as expected. Normalized mean activity estimates were preserved between the reference and automated quantification techniques with relative errors below 10 % in most of the organs considered. The proposed automated quantification technique is

  2. Registration-based initialization during radiation therapy planning

    Science.gov (United States)

    Gopalakrishnan, Girish; Mullick, Rakesh

    2007-03-01

    An established challenge in the field of image analysis has been the registration of images having a large initial misalignment. For example in chemo and Radiation Therapy Planning (RTP), there is often a need to register an image delineating a specific anatomy (usually in the surgery position) with that of a whole body image (obtained preoperatively). In such a scenario, there is room for a large misalignment between the two images that are required to be aligned. Large misalignments are traditionally handled in two ways: 1) Semi-automatically with a user initialization or 2) With the help of the origin fields in the image header. The first approach is user dependant and the second method can be used only if the two images are obtained from the same scanner with consistent origins. Our methodology extends a typical registration framework by selecting components that are capable of searching a large parameter space without settling on local optima. We have used an optimizer that is based on an Evolutionary Scheme along with an information theory based similarity metric that can address these needs. The attempt in this study is to convert a large misalignment problem to a small misalignment problem that can then be handled using application specific registration algorithms. Further improvements along local areas can be obtained by subjecting the image to a non-rigid transformation. We have successfully registered the following pairs of images without any user initialization: CTAC - simCT (neuro, lungs); MRPET/ CT (neuro, liver); T2-SPGR (neuro).

  3. Medical image registration using sparse coding of image patches.

    Science.gov (United States)

    Afzali, Maryam; Ghaffari, Aboozar; Fatemizadeh, Emad; Soltanian-Zadeh, Hamid

    2016-06-01

    Image registration is a basic task in medical image processing applications like group analysis and atlas construction. Similarity measure is a critical ingredient of image registration. Intensity distortion of medical images is not considered in most previous similarity measures. Therefore, in the presence of bias field distortions, they do not generate an acceptable registration. In this paper, we propose a sparse based similarity measure for mono-modal images that considers non-stationary intensity and spatially-varying distortions. The main idea behind this measure is that the aligned image is constructed by an analysis dictionary trained using the image patches. For this purpose, we use "Analysis K-SVD" to train the dictionary and find the sparse coefficients. We utilize image patches to construct the analysis dictionary and then we employ the proposed sparse similarity measure to find a non-rigid transformation using free form deformation (FFD). Experimental results show that the proposed approach is able to robustly register 2D and 3D images in both simulated and real cases. The proposed method outperforms other state-of-the-art similarity measures and decreases the transformation error compared to the previous methods. Even in the presence of bias field distortion, the proposed method aligns images without any preprocessing.

  4. Myocardial deformation from tagged MRI in hypertrophic cardiomyopathy using an efficient registration strategy

    Science.gov (United States)

    Piella, G.; De Craene, M.; Oubel, E.; Larrabide, I.; Huguet, M.; Bijnens, B. H.; Frangi, A. F.

    2009-02-01

    This paper combines different parallelization strategies for speeding up motion and deformation computation by non-rigid registration of a sequence of images. The registration is performed in a two-level acceleration approach: (1) parallelization of each registration process using MPI and/or threads, and (2) distribution of the sequential registrations over a cluster. On a 24-node double quad-core Intel Xeon (2.66 GHz CPU, 16 GB RAM) cluster, the method is demonstrated to efficiently compute the deformation of a cardiac sequence reducing the computation time from more than 3 hours to a couple of minutes (for low downsampled images). It is shown that the distribution of the sequential registrations over the cluster together with the parallelization of each pairwise registration by multithreading lowers the computation time towards values compatible with clinical requirements (a few minutes per patient). The combination of MPI and multithreading is only advantageous for large input data sizes. Performances are assessed for the specific scenario of aligning cardiac sequences of taggedMagnetic Resonance (tMR) images, with the aim of comparing strain in healthy subjects and hypertrophic cardiomyopathy (HCM) patients. In particular, we compared the distribution of systolic strain in both populations. On average, HCM patients showed lower average values of strain with larger deviation due to the coexistence of regions with impaired deformation and regions with normal deformation.

  5. A Markov random field approach to group-wise registration/mosaicing with application to ultrasound.

    Science.gov (United States)

    Kutarnia, Jason; Pedersen, Peder

    2015-08-01

    In this paper we present a group-wise non-rigid registration/mosaicing algorithm based on block-matching, which is developed within a probabilistic framework. The discrete form of its energy functional is linked to a Markov Random Field (MRF) containing double and triple cliques, which can be effectively optimized using modern MRF optimization algorithms popular in computer vision. Also, the registration problem is simplified by introducing a mosaicing function which partitions the composite volume into regions filled with data from unique, partially overlapping source volumes. Ultrasound confidence maps are incorporated into the registration framework in order to give accurate results in the presence of image artifacts. The algorithm is initially tested on simulated images where shadows have been generated. Also, validation results for the group-wise registration algorithm using real ultrasound data from an abdominal phantom are presented. Finally, composite obstetrics image volumes are constructed using clinical scans of pregnant subjects, where fetal movement makes registration/mosaicing especially difficult. In addition, results are presented suggesting that a fusion approach to MRF registration can produce accurate displacement fields much faster than standard approaches.

  6. The spin evolution of the pulsars with non-rigid core

    CERN Document Server

    Barsukov, D P; Tsygan, A I

    2014-01-01

    We formulate a model of pulsar spin evolution (braking, inclination angle evolution and radiative precession) taking into account the non-rigidity of neutron star rotation. We discuss two simple limiting cases of this model and show that the evolution of the inclination angle substantially depends on the model of crust-core interaction. The non-rigidity of core rotation accelerates the inclination angle evolution and makes all pulsars evolve to the orthogonal state. The size of the effect depends on the amount of differentially rotating matter and mechanism of its interaction with the rest of the star. Since the rapid volution of the inclination angle apparently contradicts the observational data, our results may be used as an additional test for the theories of the cores of neutron stars.

  7. Q-Conjugacy character table for the non-rigid group of 2,3-dimethylbutane

    Directory of Open Access Journals (Sweden)

    MOHAMMAD REZA DARAFSHEH

    2009-01-01

    Full Text Available Maturated and unmaturated groups were introduced by the Japanese chemist Shinsaku Fujita, who used them in the markaracter table and the Q-conjugacy character table of a finite group. He then applied his results in this area of research to enumerate isomers of molecules. Using the non-rigid group theory, it was shown by the second author that the full non-rigid (f-NRG group of 2,3--dimethylbutane is isomorphic to the group (Z3×Z3×Z3×Z3:Z2 of order 162 with 54 conjugacy classes. Here (Z3×Z3×Z3×Z3:Z2 denotes the semi direct product of four copies of Z3 by Z2, where Zn is a cyclic group of order n. In this paper, it is shown with the GAP program that this group has 30 dominant classes (similarly, Q-conjugacy characters and that 24 of them are unmatured (similarly, Q-conjugacy characters such that they are the sum of two irreducible characters. Then, the Q-conjugacy character table of the unmatured full non-rigid group 2,3-dimethylbutane is derived.

  8. Image Registration Workshop Proceedings

    Science.gov (United States)

    LeMoigne, Jacqueline (Editor)

    1997-01-01

    Automatic image registration has often been considered as a preliminary step for higher-level processing, such as object recognition or data fusion. But with the unprecedented amounts of data which are being and will continue to be generated by newly developed sensors, the very topic of automatic image registration has become and important research topic. This workshop presents a collection of very high quality work which has been grouped in four main areas: (1) theoretical aspects of image registration; (2) applications to satellite imagery; (3) applications to medical imagery; and (4) image registration for computer vision research.

  9. Estimation of independent non-linear deformation modes for analysis of craniofacial malformations in crouzon mice

    DEFF Research Database (Denmark)

    Hansen, Michael Sass; Olafsdóttir, Hildur; Darvann, Tron Andre;

    2007-01-01

    Crouzon syndrome is a genetic disease resulting in premature fusion of cranial sutures and synchondroses causing craniosynostosis. A decade ago the Crouzon gene was discovered, and recently the first mouse model of the syndrome was generated. In this study, a set of Micro CT scannings of the heads...... of wild-type (normal) mice and Crouzon mice were investigated. We present for what we believe is the first time, a statistical deformation model based on independent component analysis (ICA). A set of deformation parameters for each mouse was calculated using a B-spline-based nonrigid registration. From...

  10. Registering prostate external beam radiotherapy with a boost from high-dose-rate brachytherapy: a comparative evaluation of deformable registration algorithms

    International Nuclear Information System (INIS)

    Registering CTs for patients receiving external beam radiotherapy (EBRT) with a boost dose from high-dose-rate brachytherapy (HDR) can be challenging due to considerable image discrepancies (e.g. rectal fillings, HDR needles, HDR artefacts and HDR rectal packing materials). This study is the first to comparatively evaluate image processing and registration methods used to register the rectums in EBRT and HDR CTs of prostate cancer patients. The focus is on the rectum due to planned future analysis of rectal dose-volume response. For 64 patients, the EBRT CT was retrospectively registered to the HDR CT with rigid registration and non-rigid registration methods in VelocityAI. Image processing was undertaken on the HDR CT and the rigidly-registered EBRT CT to reduce the impact of discriminating features on alternative non-rigid registration methods applied in the software suite for Deformable Image Registration and Adaptive Radiotherapy Research (DIRART) using the Horn-Schunck optical flow and Demons algorithms. The propagated EBRT-rectum structures were compared with the HDR structure using the Dice similarity coefficient (DSC), Hausdorff distance (HD) and average surface distance (ASD). The image similarity was compared using mutual information (MI) and root mean squared error (MSE). The displacement vector field was assessed via the Jacobian determinant (JAC). The post-registration alignments of rectums for 21 patients were visually assessed. The greatest improvement in the median DSC relative to the rigid registration result was 35 % for the Horn-Schunck algorithm with image processing. This algorithm also provided the best ASD results. The VelocityAI algorithms provided superior HD, MI, MSE and JAC results. The visual assessment indicated that the rigid plus deformable multi-pass method within VelocityAI resulted in the best rectum alignment. The DSC, ASD and HD improved significantly relative to the rigid registration result if image processing was applied prior

  11. Locally Orderless Registration Code

    DEFF Research Database (Denmark)

    2012-01-01

    This is code for the TPAMI paper "Locally Orderless Registration". The code requires intel threadding building blocks installed and is provided for 64 bit on mac, linux and windows.......This is code for the TPAMI paper "Locally Orderless Registration". The code requires intel threadding building blocks installed and is provided for 64 bit on mac, linux and windows....

  12. Information from the Registration Service

    CERN Document Server

    GS Department

    2011-01-01

    Please note that the Registration Service (Bldg 55-1st floor) will be exceptionally open during the annual end of year closure from 10:00 to 12:00 on the following days: 22, 23, 26, 27,28, 29 et 30 December 2011 and 2,3, et 4 January 2012. All the activities related to the Registration Service will be operational: registration for contractors’ personnel; registrations for professional visits; access cards; car stickers; biometric registration. The Registration Service

  13. Experiment and numerical simulation on the characteristics of fluid–structure interactions of non-rigid airships

    Directory of Open Access Journals (Sweden)

    Xiaocui Wu

    2015-11-01

    Full Text Available Fluid–structure interaction is an important issue for non-rigid airships with inflated envelopes. In this study, a wind tunnel test is conducted, and a loosely coupled procedure is correspondingly established for numerical simulation based on computational fluid dynamics and nonlinear finite element analysis methods. The typical results of the numerical simulation and wind tunnel experiment, including the overall lift and deformation, are in good agreement with each other. The results obtained indicate that the effect of fluid–structure interaction is noticeable and should be considered for non-rigid airships. Flow-induced deformation can further intensify the upward lift force and pitching moment, which can lead to a large deformation. Under a wind speed of 15 m/s, the lift force of the non-rigid model is increased to approximately 60% compared with that of the rigid model under a high angle of attack.

  14. The stability and control characteristics of the neutrally bouyant non-rigid airship

    OpenAIRE

    Goineau, F.

    1999-01-01

    The response to controls of a neutrally buoyant non-rigid airship was investigated for a range of speeds from the hover to 30 m/s using a non-linear simulation model. The responses shown include both flight path and a range of motion variables. The latter show the influence of the stability modes on control. The controls included in the airship model comprise equivalent elevator, equivalent rudder, thrust magnitude and thrust vector direction. A linearised state model of the airship was o...

  15. Automated registration of diagnostic to prediagnostic x-ray mammograms: Evaluation and comparison to radiologists' accuracy

    Energy Technology Data Exchange (ETDEWEB)

    Pinto Pereira, Snehal M.; Hipwell, John H.; McCormack, Valerie A.; Tanner, Christine; Moss, Sue M.; Wilkinson, Louise S.; Khoo, Lisanne A. L.; Pagliari, Catriona; Skippage, Pippa L.; Kliger, Carole J.; Hawkes, David J.; Santos Silva, Isabel M. dos [Cancer Research UK Epidemiology and Genetics Group, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT (United Kingdom); Centre for Medical Image Computing, University College London, London WC1E 6BT (United Kingdom); Lifestyle and Cancer Group, International Agency for Research on Cancer, 150 cours Albert Thomas, Lyon 69008 (France); Centre for Medical Image Computing, University College London, London WC1E 6BT (United Kingdom); Cancer Screening Evaluation Unit, Institute of Cancer Research, Surrey SM2 5NG (United Kingdom); St. George' s Healthcare NHS Trust and South West London Breast Screening Service, London SW17 0QT (United Kingdom); Centre for Medical Image Computing, University College London, London WC1E 6BT (United Kingdom); Cancer Research UK Epidemiology and Genetics Group, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT (United Kingdom)

    2010-09-15

    Purpose: To compare and evaluate intensity-based registration methods for computation of serial x-ray mammogram correspondence. Methods: X-ray mammograms were simulated from MRIs of 20 women using finite element methods for modeling breast compressions and employing a MRI/x-ray appearance change model. The parameter configurations of three registration methods, affine, fluid, and free-form deformation (FFD), were optimized for registering x-ray mammograms on these simulated images. Five mammography film readers independently identified landmarks (tumor, nipple, and usually two other normal features) on pairs of diagnostic and corresponding prediagnostic digitized images from 52 breast cancer cases. Landmarks were independently reidentified by each reader. Target registration errors were calculated to compare the three registration methods using the reader landmarks as a gold standard. Data were analyzed using multilevel methods. Results: Between-reader variability varied with landmark (p<0.01) and screen (p=0.03), with between-reader mean distance (mm) in point location on the diagnostic/prediagnostic images of 2.50 (95% CI 1.95, 3.15)/2.84 (2.24, 3.55) for nipples and 4.26 (3.43, 5.24)/4.76 (3.85, 5.84) for tumors. Registration accuracy was sensitive to the type of landmark and the amount of breast density. For dense breasts ({>=}40%), the affine and fluid methods outperformed FFD. For breasts with lower density, the affine registration surpassed both fluid and FFD. Mean accuracy (mm) of the affine registration varied between 3.16 (95% CI 2.56, 3.90) for nipple points in breasts with density 20%-39% and 5.73 (4.80, 6.84) for tumor points in breasts with density <20%. Conclusions: Affine registration accuracy was comparable to that between independent film readers. More advanced two-dimensional nonrigid registration algorithms were incapable of increasing the accuracy of image alignment when compared to affine registration.

  16. A hybrid biomechanical intensity based deformable image registration of lung 4DCT

    Science.gov (United States)

    Samavati, Navid; Velec, Michael; Brock, Kristy

    2015-04-01

    Deformable image registration (DIR) has been extensively studied over the past two decades due to its essential role in many image-guided interventions (IGI). IGI demands a highly accurate registration that maintains its accuracy across the entire region of interest. This work evaluates the improvement in accuracy and consistency by refining the results of Morfeus, a biomechanical model-based DIR algorithm. A hybrid DIR algorithm is proposed based on, a biomechanical model-based DIR algorithm and a refinement step based on a B-spline intensity-based algorithm. Inhale and exhale reconstructions of four-dimensional computed tomography (4DCT) lung images from 31 patients were initially registered using the biomechanical DIR by modeling contact surface between the lungs and the chest cavity. The resulting deformations were then refined using the intensity-based algorithm to reduce any residual uncertainties. Important parameters in the intensity-based algorithm, including grid spacing, number of pyramids, and regularization coefficient, were optimized on 10 randomly-chosen patients (out of 31). Target registration error (TRE) was calculated by measuring the Euclidean distance of common anatomical points on both images after registration. For each patient a minimum of 30 points/lung were used. Grid spacing of 8 mm, 5 levels of grid pyramids, and regularization coefficient of 3.0 were found to provide optimal results on 10 randomly chosen patients. Overall the entire patient population (n = 31), the hybrid method resulted in mean ± SD (90th%) TRE of 1.5 ± 1.4 (2.9) mm compared to 3.1 ± 1.9 (5.6) using biomechanical DIR and 2.6 ± 2.5 (6.1) using intensity-based DIR alone. The proposed hybrid biomechanical modeling intensity based algorithm is a promising DIR technique which could be used in various IGI procedures. The current investigation shows the efficacy of this approach for the registration of 4DCT images of the lungs with average accuracy of 1.5 mm.

  17. Nonrigid motion correction in 3D using autofocusing with localized linear translations.

    Science.gov (United States)

    Cheng, Joseph Y; Alley, Marcus T; Cunningham, Charles H; Vasanawala, Shreyas S; Pauly, John M; Lustig, Michael

    2012-12-01

    MR scans are sensitive to motion effects due to the scan duration. To properly suppress artifacts from nonrigid body motion, complex models with elements such as translation, rotation, shear, and scaling have been incorporated into the reconstruction pipeline. However, these techniques are computationally intensive and difficult to implement for online reconstruction. On a sufficiently small spatial scale, the different types of motion can be well approximated as simple linear translations. This formulation allows for a practical autofocusing algorithm that locally minimizes a given motion metric--more specifically, the proposed localized gradient-entropy metric. To reduce the vast search space for an optimal solution, possible motion paths are limited to the motion measured from multichannel navigator data. The novel navigation strategy is based on the so-called "Butterfly" navigators, which are modifications of the spin-warp sequence that provides intrinsic translational motion information with negligible overhead. With a 32-channel abdominal coil, sufficient number of motion measurements were found to approximate possible linear motion paths for every image voxel. The correction scheme was applied to free-breathing abdominal patient studies. In these scans, a reduction in artifacts from complex, nonrigid motion was observed. PMID:22307933

  18. Visitor Registration System

    Data.gov (United States)

    US Agency for International Development — Visitor Registration System (VRS) streamlines visitor check-in and check-out process for expediting visitors into USAID. The system captures visitor information...

  19. Pesticide Registration Information System

    Data.gov (United States)

    U.S. Environmental Protection Agency — PRISM provides an integrated, web portal for all pesticide related data, communications, registrations and transactions for OPP and its stakeholders, partners and...

  20. Locally Orderless Registration

    CERN Document Server

    Darkner, Sune

    2012-01-01

    Image registration is an important tool for medical image analysis and is used to bring images into the same reference frame by warping the coordinate field of one image, such that some similarity measure is minimized. We study similarity in image registration in the context of Locally Orderless Images (LOI), which is the natural way to study density estimates and reveals the 3 fundamental scales: the measurement scale, the intensity scale, and the integration scale. This paper has three main contributions: Firstly, we rephrase a large set of popular similarity measures into a common framework, which we refer to as Locally Orderless Registration, and which makes full use of the features of local histograms. Secondly, we extend the theoretical understanding of the local histograms. Thirdly, we use our framework to compare two state-of-the-art intensity density estimators for image registration: The Parzen Window (PW) and the Generalized Partial Volume (GPV), and we demonstrate their differences on a popular si...

  1. Registration of the cancer

    International Nuclear Information System (INIS)

    A database for the registration of the cancer was designed in ambient access, of the Microsoft Office, to take the registrations at national level. With this database the statistics will be obtained about the incidence of the cancer in the population, evaluation of the sanitary services of prevention, diagnose and treatment of the illness, etc. The used codes are according to the listings of code of the Ministry of Health (MINSA) and OPS

  2. Understanding geological processes: Visualization of rigid and non-rigid transformations

    Science.gov (United States)

    Shipley, T. F.; Atit, K.; Manduca, C. A.; Ormand, C. J.; Resnick, I.; Tikoff, B.

    2012-12-01

    Visualizations are used in the geological sciences to support reasoning about structures and events. Research in cognitive sciences offers insights into the range of skills of different users, and ultimately how visualizations might support different users. To understand the range of skills needed to reason about earth processes we have developed a program of research that is grounded in the geosciences' careful description of the spatial and spatiotemporal patterns associated with earth processes. In particular, we are pursuing a research program that identifies specific spatial skills and investigates whether and how they are related to each other. For this study, we focus on a specific question: Is there an important distinction in the geosciences between rigid and non-rigid deformation? To study a general spatial thinking skill we employed displays with non-geological objects that had been altered by rigid change (rotation), and two types of non-rigid change ("brittle" (or discontinuous) and "ductile" (or continuous) deformation). Disciplinary scientists (geosciences and chemistry faculty), and novices (non-science faculty and undergraduate psychology students) answered questions that required them to visualize the appearance of the object before the change. In one study, geologists and chemists were found to be superior to non-science faculty in reasoning about rigid rotations (e.g., what an object would look like from a different perspective). Geologists were superior to chemists in reasoning about brittle deformations (e.g., what an object looked like before it was broken - here the object was a word cut into many fragments displaced in different directions). This finding is consistent with two hypotheses: 1) Experts are good at visualizing the types of changes required for their domain; and 2) Visualization of rigid and non-rigid changes are not the same skill. An additional important finding is that there was a broad range of skill in both rigid and non-rigid

  3. Regional lung function and mechanics using image registration

    Science.gov (United States)

    Ding, Kai

    The main function of the respiratory system is gas exchange. Since many disease or injury conditions can cause biomechanical or material property changes that can alter lung function, there is a great interest in measuring regional lung function and mechanics. In this thesis, we present a technique that uses multiple respiratory-gated CT images of the lung acquired at different levels of inflation with both breath-hold static scans and retrospectively reconstructed 4D dynamic scans, along with non-rigid 3D image registration, to make local estimates of lung tissue function and mechanics. We validate our technique using anatomical landmarks and functional Xe-CT estimated specific ventilation. The major contributions of this thesis include: (1) developing the registration derived regional expansion estimation approach in breath-hold static scans and dynamic 4DCT scans, (2) developing a method to quantify lobar sliding from image registration derived displacement field, (3) developing a method for measurement of radiation-induced pulmonary function change following a course of radiation therapy, (4) developing and validating different ventilation measures in 4DCT. The ability of our technique to estimate regional lung mechanics and function as a surrogate of the Xe-CT ventilation imaging for the entire lung from quickly and easily obtained respiratory-gated images, is a significant contribution to functional lung imaging because of the potential increase in resolution, and large reductions in imaging time, radiation, and contrast agent exposure. Our technique may be useful to detect and follow the progression of lung disease such as COPD, may be useful as a planning tool during RT planning, may be useful for tracking the progression of toxicity to nearby normal tissue during RT, and can be used to evaluate the effectiveness of a treatment post-therapy.

  4. User Registration in EOSDIS

    Science.gov (United States)

    Murphy, K. J.; Mitchell, A. E.

    2009-12-01

    Throughout the lifetime of EOSDIS the topic of user registration has received varied attention. Initially, for example, users ordering data from the Earth Science Data Gateway were required to register for delivery of media orders, to check order status and save profile information for future interactions. As EOSDIS embraced evolution of its data systems, the mostly centralized search and order system was replaced with a more diverse set of interfaces allowing (mostly) anonymous online access to data, tools and services. The changes to EOSDIS were embraced by users but the anonymous nature of the interaction made it more difficult to characterize users, capture metrics and provide customized services that benefit users. Additionally, new tools and interfaces have been developed without a centralized registration system. Currently a patchwork of independent registration systems exists throughout EOSDIS for ordering data and interacting with online tools and services. Each requires a separate username and password that must be managed by users. A consolidation of registration systems presents an opportunity to improve not only the user experience through tool customization and simplification of password management, but the understanding of users. This work discusses the options for implementing a common user registration for the EOSDIS, anticipated benefits and pitfalls.

  5. SU-C-18A-04: 3D Markerless Registration of Lung Based On Coherent Point Drift: Application in Image Guided Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Nasehi Tehrani, J; Wang, J [UT Southwestern Medical Center, Dallas, TX (United States); Guo, X [University of Texas at Dallas, Richardson, TX (United States); Yang, Y [The University of New Mexico, New Mexico, NM (United States)

    2014-06-01

    Purpose: This study evaluated a new probabilistic non-rigid registration method called coherent point drift for real time 3D markerless registration of the lung motion during radiotherapy. Method: 4DCT image datasets Dir-lab (www.dir-lab.com) have been used for creating 3D boundary element model of the lungs. For the first step, the 3D surface of the lungs in respiration phases T0 and T50 were segmented and divided into a finite number of linear triangular elements. Each triangle is a two dimensional object which has three vertices (each vertex has three degree of freedom). One of the main features of the lungs motion is velocity coherence so the vertices that creating the mesh of the lungs should also have features and degree of freedom of lung structure. This means that the vertices close to each other tend to move coherently. In the next step, we implemented a probabilistic non-rigid registration method called coherent point drift to calculate nonlinear displacement of vertices between different expiratory phases. Results: The method has been applied to images of 10-patients in Dir-lab dataset. The normal distribution of vertices to the origin for each expiratory stage were calculated. The results shows that the maximum error of registration between different expiratory phases is less than 0.4 mm (0.38 SI, 0.33 mm AP, 0.29 mm RL direction). This method is a reliable method for calculating the vector of displacement, and the degrees of freedom (DOFs) of lung structure in radiotherapy. Conclusions: We evaluated a new 3D registration method for distribution set of vertices inside lungs mesh. In this technique, lungs motion considering velocity coherence are inserted as a penalty in regularization function. The results indicate that high registration accuracy is achievable with CPD. This method is helpful for calculating of displacement vector and analyzing possible physiological and anatomical changes during treatment.

  6. Improving target delineation on 4-dimensional CT scans in stage I NSCLC using a deformable registration tool

    International Nuclear Information System (INIS)

    Introduction: Correct target definition is crucial in stereotactic radiotherapy for lung tumors. We evaluated use of deformable registration (DR) for target contouring on 4-dimensional (4D) CT scans. Materials and methods: Three clinicians contoured gross tumor volume (GTV) in an end-inspiration phase of 4DCT of 6 patients on two occasions. Two clinicians contoured GTVs in all phases of 4DCT and on maximum intensity projections (MIP). The initial GTV was auto-propagated to 9 other phases using a B-spline algorithm (VelocityAI). Internal target volumes (ITVs) generated were (i) ITV10manual encompassing all physician-contoured GTVs, (ii) ITV-MIPoptimized from MIP after review of individual 4DCT phases, (iii) ITV10deformed encompassing auto-propagated GTVs using DR, and (iv) ITV10deformed-optimized, from an ITV10deformed target that was modified to form a 'clinically optimal' ITV. Volume-overlaps were scored using Dice's Similarity Coefficients (DSCs). Results: Intra-clinician GTV reproducibility was greater than inter-clinician reproducibility (mean DSC 0.93 vs. 0.88, p optimized differed from the ITV10deformed-optimized. In all patients, the DSC between ITV10deformed-optimized and ITV10deformed was higher than that between ITV10deformed-optimized and ITV-MIPoptimized (p < 0.02 T-test). Conclusion: ITVs created in stage I tumors using DR were closer to 'clinically optimal' ITVs than was the case with a MIP-modified approach.

  7. Development and application of pulmonary structure-function registration methods: towards pulmonary image-guidance tools for improved airway targeted therapies and outcomes

    Science.gov (United States)

    Guo, Fumin; Pike, Damien; Svenningsen, Sarah; Coxson, Harvey O.; Drozd, John J.; Yuan, Jing; Fenster, Aaron; Parraga, Grace

    2014-03-01

    Objectives: We aimed to develop a way to rapidly generate multi-modality (MRI-CT) pulmonary imaging structurefunction maps using novel non-rigid image registration methods. This objective is part of our overarching goal to provide an image processing pipeline to generate pulmonary structure-function maps and guide airway-targeted therapies. Methods: Anatomical 1H and functional 3He MRI were acquired in 5 healthy asymptomatic ex-smokers and 7 ex-smokers with chronic obstructive pulmonary disease (COPD) at inspiration breath-hold. Thoracic CT was performed within ten minutes of MRI using the same breath-hold volume. Landmark-based affine registration methods previously validated for imaging of COPD, was based on corresponding fiducial markers located in both CT and 1H MRI coronal slices and compared with shape-based CT-MRI non-rigid registration. Shape-based CT-MRI registration was developed by first identifying the shapes of the lung cavities manually, and then registering the two shapes using affine and thin-plate spline algorithms. We compared registration accuracy using the fiducial localization error (FLE) and target registration error (TRE). Results: For landmark-based registration, the TRE was 8.4±5.3 mm for whole lung and 7.8±4.6 mm for the R and L lungs registered independently (p=0.4). For shape-based registration, the TRE was 8.0±4.6 mm for whole lung as compared to 6.9±4.4 mm for the R and L lung registered independently and this difference was significant (p=0.01). The difference for shape-based (6.9±4.4 mm) and landmark-based R and L lung registration (7.8±4.6 mm) was also significant (p=.04) Conclusion: Shape-based registration TRE was significantly improved compared to landmark-based registration when considering L and R lungs independently.

  8. Non-Rigid Object Contour Tracking via a Novel Supervised Level Set Model.

    Science.gov (United States)

    Sun, Xin; Yao, Hongxun; Zhang, Shengping; Li, Dong

    2015-11-01

    We present a novel approach to non-rigid objects contour tracking in this paper based on a supervised level set model (SLSM). In contrast to most existing trackers that use bounding box to specify the tracked target, the proposed method extracts the accurate contours of the target as tracking output, which achieves better description of the non-rigid objects while reduces background pollution to the target model. Moreover, conventional level set models only emphasize the regional intensity consistency and consider no priors. Differently, the curve evolution of the proposed SLSM is object-oriented and supervised by the specific knowledge of the targets we want to track. Therefore, the SLSM can ensure a more accurate convergence to the exact targets in tracking applications. In particular, we firstly construct the appearance model for the target in an online boosting manner due to its strong discriminative power between the object and the background. Then, the learnt target model is incorporated to model the probabilities of the level set contour by a Bayesian manner, leading the curve converge to the candidate region with maximum likelihood of being the target. Finally, the accurate target region qualifies the samples fed to the boosting procedure as well as the target model prepared for the next time step. We firstly describe the proposed mechanism of two-phase SLSM for single target tracking, then give its generalized multi-phase version for dealing with multi-target tracking cases. Positive decrease rate is used to adjust the learning pace over time, enabling tracking to continue under partial and total occlusion. Experimental results on a number of challenging sequences validate the effectiveness of the proposed method. PMID:26099142

  9. Automated registration of multispectral MR vessel wall images of the carotid artery

    Energy Technology Data Exchange (ETDEWEB)

    Klooster, R. van ' t; Staring, M.; Reiber, J. H. C.; Lelieveldt, B. P. F.; Geest, R. J. van der, E-mail: rvdgeest@lumc.nl [Department of Radiology, Division of Image Processing, Leiden University Medical Center, 2300 RC Leiden (Netherlands); Klein, S. [Department of Radiology and Department of Medical Informatics, Biomedical Imaging Group Rotterdam, Erasmus MC, Rotterdam 3015 GE (Netherlands); Kwee, R. M.; Kooi, M. E. [Department of Radiology, Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht 6202 AZ (Netherlands)

    2013-12-15

    moving image after registration. Results: The average required manual translation per image slice was 1.33 mm. Translations were larger as the patient was longer inside the scanner. Manual alignment took 187.5 s per patient resulting in a mean surface distance of 0.271 ± 0.127 mm. After minimal user interaction to generate the mask in the fixed image, the remaining sequences are automatically registered with a computation time of 52.0 s per patient. The optimal registration strategy used a circular mask with a diameter of 10 mm, a 3D B-spline transformation model with a control point spacing of 15 mm, mutual information as image similarity metric, and the precontrast T1W TSE as fixed image. A mean surface distance of 0.288 ± 0.128 mm was obtained with these settings, which is very close to the accuracy of the manual alignment procedure. The exact registration parameters and software were made publicly available. Conclusions: An automated registration method was developed and optimized, only needing two mouse clicks to mark the start and end point of the artery. Validation on a large group of patients showed that automated image registration has similar accuracy as the manual alignment procedure, substantially reducing the amount of user interactions needed, and is multiple times faster. In conclusion, the authors believe that the proposed automated method can replace the current manual procedure, thereby reducing the time to analyze the images.

  10. SU-D-18A-01: Tumor Motion Tracking with a Regional Deformable Registration Model for Four Dimensional Radiation Treatment of Lung Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Chao, M; Lo, Y; Yuan, Y; Sheu, R; Rosenzweig, K [The Mount Sinai Medical Center, NY, NY (United States)

    2014-06-01

    Purpose: To develop a tumor motion model from four-dimensional computed tomography (4DCT) of thoracic patients and demonstrate its impact on 4D radiation therapy simulation. Methods: A regional deformable image registration algorithm was introduced to extract tumor motion out of patient's breathing cycle. The gross target volume (GTV) was manually delineated on a selected phase of 4DCT and a subregion with 10mm margin supplemented to the GTV was created on the Eclipse treatment planning system (Varian Medical Systems, Palo Alto, CA). Together with 4DCT the structures were exported into an inhouse research platform. A free form B-Spline deformable registration was carried out to map the subregion to other respiratory phases. The displacement vector fields were employed to propagate GTV contours with which the center of mass (CoM) of the GTV was computed for each breathing phase of 4DCT. The resultant GTV motion and its volumetric shape are utilized to facilitate 4D treatment planning. Five lung cancer patients undergoing stereotactic body radiation therapy were enrolled and their 4DCT sets were included in the study. Results: Application of the algorithm to five thoracic patients indicates that clinically satisfactory outcomes were achievable with a spatial accuracy better than 2mm for GTV contour propagation between adjacent phases, and 3mm between opposite phases. The GTV CoM was found to be in the range of 2.0mm through 2.5cm, depending upon the tumor location. Compared to the traditional whole image based registration, the computation of the regional model was found to be an order of magnitude more efficient. Conclusion: A regional deformable registration model was implemented to extract tumor motion. It will have widespread application in 4D radiation treatment planning in the future to maximally utilize the available spatial-tempo information.

  11. Pro Forma Registration of Companies

    DEFF Research Database (Denmark)

    Werlauff, Erik

    2010-01-01

    The article analyses the view taken by Community law on companies' pro forma registration in another EU or EEA country. Community law recognises pro forma registration under company law, i.e. a brass plate is sufficient, whereas it does not recognise pro forma registration under tax law, i...

  12. SU-E-J-114: A Practical Hybrid Method for Improving the Quality of CT-CBCT Deformable Image Registration for Head and Neck Radiotherapy

    International Nuclear Information System (INIS)

    Purpose: Accurate deformable image registration (DIR) between CT and CBCT in H&N is challenging. In this study, we propose a practical hybrid method that uses not only the pixel intensities but also organ physical properties, structure volume of interest (VOI), and interactive local registrations. Methods: Five oropharyngeal cancer patients were selected retrospectively. For each patient, the planning CT was registered to the last fraction CBCT, where the anatomy difference was largest. A three step registration strategy was tested; Step1) DIR using pixel intensity only, Step2) DIR with additional use of structure VOI and rigidity penalty, and Step3) interactive local correction. For Step1, a public-domain open-source DIR algorithm was used (cubic B-spline, mutual information, steepest gradient optimization, and 4-level multi-resolution). For Step2, rigidity penalty was applied on bony anatomies and brain, and a structure VOI was used to handle the body truncation such as the shoulder cut-off on CBCT. Finally, in Step3, the registrations were reviewed on our in-house developed software and the erroneous areas were corrected via a local registration using level-set motion algorithm. Results: After Step1, there were considerable amount of registration errors in soft tissues and unrealistic stretching in the posterior to the neck and near the shoulder due to body truncation. The brain was also found deformed to a measurable extent near the superior border of CBCT. Such errors could be effectively removed by using a structure VOI and rigidity penalty. The rest of the local soft tissue error could be corrected using the interactive software tool. The estimated interactive correction time was approximately 5 minutes. Conclusion: The DIR using only the image pixel intensity was vulnerable to noise and body truncation. A corrective action was inevitable to achieve good quality of registrations. We found the proposed three-step hybrid method efficient and practical for CT

  13. SU-E-J-114: A Practical Hybrid Method for Improving the Quality of CT-CBCT Deformable Image Registration for Head and Neck Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C; Kumarasiri, A; Chetvertkov, M; Gordon, J; Chetty, I; Siddiqui, F; Kim, J [Henry Ford Health System, Detroit, MI (United States)

    2015-06-15

    Purpose: Accurate deformable image registration (DIR) between CT and CBCT in H&N is challenging. In this study, we propose a practical hybrid method that uses not only the pixel intensities but also organ physical properties, structure volume of interest (VOI), and interactive local registrations. Methods: Five oropharyngeal cancer patients were selected retrospectively. For each patient, the planning CT was registered to the last fraction CBCT, where the anatomy difference was largest. A three step registration strategy was tested; Step1) DIR using pixel intensity only, Step2) DIR with additional use of structure VOI and rigidity penalty, and Step3) interactive local correction. For Step1, a public-domain open-source DIR algorithm was used (cubic B-spline, mutual information, steepest gradient optimization, and 4-level multi-resolution). For Step2, rigidity penalty was applied on bony anatomies and brain, and a structure VOI was used to handle the body truncation such as the shoulder cut-off on CBCT. Finally, in Step3, the registrations were reviewed on our in-house developed software and the erroneous areas were corrected via a local registration using level-set motion algorithm. Results: After Step1, there were considerable amount of registration errors in soft tissues and unrealistic stretching in the posterior to the neck and near the shoulder due to body truncation. The brain was also found deformed to a measurable extent near the superior border of CBCT. Such errors could be effectively removed by using a structure VOI and rigidity penalty. The rest of the local soft tissue error could be corrected using the interactive software tool. The estimated interactive correction time was approximately 5 minutes. Conclusion: The DIR using only the image pixel intensity was vulnerable to noise and body truncation. A corrective action was inevitable to achieve good quality of registrations. We found the proposed three-step hybrid method efficient and practical for CT

  14. Inter and intra-modal deformable registration: continuous deformations meet efficient optimal linear programming.

    Science.gov (United States)

    Glocker, Ben; Paragios, Nikos; Komodakis, Nikos; Tziritas, Georgios; Navab, Nassir

    2007-01-01

    In this paper we propose a novel non-rigid volume registration based on discrete labeling and linear programming. The proposed framework reformulates registration as a minimal path extraction in a weighted graph. The space of solutions is represented using a set of a labels which are assigned to predefined displacements. The graph topology corresponds to a superimposed regular grid onto the volume. Links between neighborhood control points introduce smoothness, while links between the graph nodes and the labels (end-nodes) measure the cost induced to the objective function through the selection of a particular deformation for a given control point once projected to the entire volume domain, Higher order polynomials are used to express the volume deformation from the ones of the control points. Efficient linear programming that can guarantee the optimal solution up to (a user-defined) bound is considered to recover the optimal registration parameters. Therefore, the method is gradient free, can encode various similarity metrics (simple changes on the graph construction), can guarantee a globally sub-optimal solution and is computational tractable. Experimental validation using simulated data with known deformation, as well as manually segmented data demonstrate the extreme potentials of our approach.

  15. Integration of breathing in radiotherapy: contribution of the image deformable registration

    International Nuclear Information System (INIS)

    As taking organ movements and deformations into account in radiotherapy for the treatment of lung cancer is a challenge as it allows the delivered dose to be increased while better sparing surrounding sane tissues, this research thesis addresses non-rigid (or deformable) registration iconic methods applied to thorax X ray computed tomography (X-ray CT) 3D acquisitions. The objective is to extract the information regarding lung and tumour movement and deformation. The author thus reports the development of deformable registration framework with several methods of regularisation of vector fields. Three main studies have been performed and are reported. In the first one, deformable registration allowed the breathe blockage reproducibility to be controlled. Experiments performed on ten patients showed that this blockage is efficient (displacement less than 5 mm), except for three of them with functional anomalies. In a second study, 4D X-ray CT acquisitions (3D X-ray CT images acquired at different moments of the normal breathing cycle) have been analysed to extract and follow thorax movements and deformations in order to take them into account in free breathing and to perform 4D dynamic dosimetric studies. A first 4D X-ray CT image model has been developed from 3D X-ray CT images acquired in breathe blockage at the end of expiration and at the end on inhalation

  16. A novel approach for establishing benchmark CBCT/CT deformable image registrations in prostate cancer radiotherapy

    Science.gov (United States)

    Kim, Jinkoo; Kumar, Sanath; Liu, Chang; Zhong, Hualiang; Pradhan, Deepak; Shah, Mira; Cattaneo, Richard; Yechieli, Raphael; Robbins, Jared R.; Elshaikh, Mohamed A.; Chetty, Indrin J.

    2013-11-01

    Deformable image registration (DIR) is an integral component for adaptive radiation therapy. However, accurate registration between daily cone-beam computed tomography (CBCT) and treatment planning CT is challenging, due to significant daily variations in rectal and bladder fillings as well as the increased noise levels in CBCT images. Another significant challenge is the lack of ‘ground-truth’ registrations in the clinical setting, which is necessary for quantitative evaluation of various registration algorithms. The aim of this study is to establish benchmark registrations of clinical patient data. Three pairs of CT/CBCT datasets were chosen for this institutional review board approved retrospective study. On each image, in order to reduce the contouring uncertainty, ten independent sets of organs were manually delineated by five physicians. The mean contour set for each image was derived from the ten contours. A set of distinctive points (round natural calcifications and three implanted prostate fiducial markers) were also manually identified. The mean contours and point features were then incorporated as constraints into a B-spline based DIR algorithm. Further, a rigidity penalty was imposed on the femurs and pelvic bones to preserve their rigidity. A piecewise-rigid registration approach was adapted to account for the differences in femur pose and the sliding motion between bones. For each registration, the magnitude of the spatial Jacobian (|JAC|) was calculated to quantify the tissue compression and expansion. Deformation grids and finite-element-model-based unbalanced energy maps were also reviewed visually to evaluate the physical soundness of the resultant deformations. Organ DICE indices (indicating the degree of overlap between registered organs) and residual misalignments of the fiducial landmarks were quantified. Manual organ delineation on CBCT images varied significantly among physicians with overall mean DICE index of only 0.7 among redundant

  17. Image registration with uncertainty analysis

    Science.gov (United States)

    Simonson, Katherine M.

    2011-03-22

    In an image registration method, edges are detected in a first image and a second image. A percentage of edge pixels in a subset of the second image that are also edges in the first image shifted by a translation is calculated. A best registration point is calculated based on a maximum percentage of edges matched. In a predefined search region, all registration points other than the best registration point are identified that are not significantly worse than the best registration point according to a predetermined statistical criterion.

  18. A review of biomechanically informed breast image registration

    Science.gov (United States)

    Hipwell, John H.; Vavourakis, Vasileios; Han, Lianghao; Mertzanidou, Thomy; Eiben, Björn; Hawkes, David J.

    2016-01-01

    Breast radiology encompasses the full range of imaging modalities from routine imaging via x-ray mammography, magnetic resonance imaging and ultrasound (both two- and three-dimensional), to more recent technologies such as digital breast tomosynthesis, and dedicated breast imaging systems for positron emission mammography and ultrasound tomography. In addition new and experimental modalities, such as Photoacoustics, Near Infrared Spectroscopy and Electrical Impedance Tomography etc, are emerging. The breast is a highly deformable structure however, and this greatly complicates visual comparison of imaging modalities for the purposes of breast screening, cancer diagnosis (including image guided biopsy), tumour staging, treatment monitoring, surgical planning and simulation of the effects of surgery and wound healing etc. Due primarily to the challenges posed by these gross, non-rigid deformations, development of automated methods which enable registration, and hence fusion, of information within and across breast imaging modalities, and between the images and the physical space of the breast during interventions, remains an active research field which has yet to translate suitable methods into clinical practice. This review describes current research in the field of breast biomechanical modelling and identifies relevant publications where the resulting models have been incorporated into breast image registration and simulation algorithms. Despite these developments there remain a number of issues that limit clinical application of biomechanical modelling. These include the accuracy of constitutive modelling, implementation of representative boundary conditions, failure to meet clinically acceptable levels of computational cost, challenges associated with automating patient-specific model generation (i.e. robust image segmentation and mesh generation) and the complexity of applying biomechanical modelling methods in routine clinical practice.

  19. Non-rigid, but not rigid, motion interferes with the processing of structural face information in developmental prosopagnosia.

    Science.gov (United States)

    Maguinness, Corrina; Newell, Fiona N

    2015-04-01

    There is growing evidence to suggest that facial motion is an important cue for face recognition. However, it is poorly understood whether motion is integrated with facial form information or whether it provides an independent cue to identity. To provide further insight into this issue, we compared the effect of motion on face perception in two developmental prosopagnosics and age-matched controls. Participants first learned faces presented dynamically (video), or in a sequence of static images, in which rigid (viewpoint) or non-rigid (expression) changes occurred. Immediately following learning, participants were required to match a static face image to the learned face. Test face images varied by viewpoint (Experiment 1) or expression (Experiment 2) and were learned or novel face images. We found similar performance across prosopagnosics and controls in matching facial identity across changes in viewpoint when the learned face was shown moving in a rigid manner. However, non-rigid motion interfered with face matching across changes in expression in both individuals with prosopagnosia compared to the performance of control participants. In contrast, non-rigid motion did not differentially affect the matching of facial expressions across changes in identity for either prosopagnosics (Experiment 3). Our results suggest that whilst the processing of rigid motion information of a face may be preserved in developmental prosopagnosia, non-rigid motion can specifically interfere with the representation of structural face information. Taken together, these results suggest that both form and motion cues are important in face perception and that these cues are likely integrated in the representation of facial identity. PMID:25737056

  20. PET and MR three-dimensional image registration based on second-order mutual information

    International Nuclear Information System (INIS)

    no mis- registration occurred. Conclusion: The results demonstrate that sub-voxel registration accuracy has been achieved using the higher-order mutual information measure and that this algorithm is robust and insensitive to intensity variations. The higher-order mutual information also has a great potential in non-rigid registration, especially in image-guided surgery. The depression of intensity grades is the most primary one of all the factors that influence the accuracy. Carefully determination of float and reference image is surely important for registration with higher-order mutual information because the accuracy of this algorithm is also greatly affected by image resolution

  1. Registration of acute stroke

    DEFF Research Database (Denmark)

    Wildenschild, Cathrine; Mehnert, Frank; Thomsen, Reimar Wernich;

    2013-01-01

    BACKGROUND: The validity of the registration of patients in stroke-specific registries has seldom been investigated, nor compared with administrative hospital discharge registries. The objective of this study was to examine the validity of the registration of patients in a stroke-specific registry...... (The Danish Stroke Registry [DSR]) and a hospital discharge registry (The Danish National Patient Registry [DNRP]). METHODS: Assuming that all patients with stroke were registered in either the DSR, DNRP or both, we first identified a sample of 75 patients registered with stroke in 2009; 25 patients...... in the DSR, 25 patients in the DNRP, and 25 patients registered in both data sources. Using the medical record as a gold standard, we then estimated the sensitivity and positive predictive value of a stroke diagnosis in the DSR and the DNRP. Secondly, we reviewed 160 medical records for all potential stroke...

  2. Articulated registration: elastic registration based on a wire-model

    Science.gov (United States)

    Martin-Fernandez, Miguel A.; Munyoz-Moreno, Emma; Martin-Fernandez, Marcos; Alberola-Lopez, Carlos

    2005-04-01

    In this paper we propose a new method of elastic registration of anatomical structures that bears an inner skeleton, such as the knee, hand or spine. Such a method has to deal with great degrees of variability, specially for the case of inter-subject registration; but even for the intra-subject case the degree of variability of images will be large since the structures we bear in mind are articulated. Rigid registration methods are clearly inappropriate for this problem, and well-known elastic methods do not usually incorporate the restriction of maintaining long skeletal structures straight. A new method is therefore needed to deal with such a situation; we call this new method "articulated registration". The inner bone skeleton is modeled with a wire model, where wires are drawn by connecting landmarks located in the main joints of the skeletal structure to be registered (long bones). The main feature of our registration method is that within the bone axis (specifically, where the wires are) an exact registration is guaranteed, while for the remaining image points an elastic registration is carried out based on a distance transform (with respect to the model wires); this causes the registration on long bones to be affine to all practical purposes, while the registration of soft tissue -- far from the bones -- is elastic. As a proof-of-concept of this method we describe the registration of hands on radiographs.

  3. Spacecraft camera image registration

    Science.gov (United States)

    Kamel, Ahmed A. (Inventor); Graul, Donald W. (Inventor); Chan, Fred N. T. (Inventor); Gamble, Donald W. (Inventor)

    1987-01-01

    A system for achieving spacecraft camera (1, 2) image registration comprises a portion external to the spacecraft and an image motion compensation system (IMCS) portion onboard the spacecraft. Within the IMCS, a computer (38) calculates an image registration compensation signal (60) which is sent to the scan control loops (84, 88, 94, 98) of the onboard cameras (1, 2). At the location external to the spacecraft, the long-term orbital and attitude perturbations on the spacecraft are modeled. Coefficients (K, A) from this model are periodically sent to the onboard computer (38) by means of a command unit (39). The coefficients (K, A) take into account observations of stars and landmarks made by the spacecraft cameras (1, 2) themselves. The computer (38) takes as inputs the updated coefficients (K, A) plus synchronization information indicating the mirror position (AZ, EL) of each of the spacecraft cameras (1, 2), operating mode, and starting and stopping status of the scan lines generated by these cameras (1, 2), and generates in response thereto the image registration compensation signal (60). The sources of periodic thermal errors on the spacecraft are discussed. The system is checked by calculating measurement residuals, the difference between the landmark and star locations predicted at the external location and the landmark and star locations as measured by the spacecraft cameras (1, 2).

  4. Polar motions equivalent to high frequency nutations for a nonrigid Earth with anelastic mantle

    Science.gov (United States)

    Mathews, P. M.; Bretagnon, P.

    2003-03-01

    The coefficients of polar motions of the rigid/nonrigid Earth in frequency bands other than the retrograde diurnal one are systematically computed using general expressions, derived here for the first time, for the prograde and retrograde torques exerted on the Earth by lunisolar potentials of arbitrary spherical harmonic type. Taken together with the already known coefficients of low frequency nutations and UT1 variations, they provide a complete characterization, with high precision, of the motions of the pole of the terrestrial reference frame in space; this is needed for high precision studies in astronomy and space geodesy. The inputs used for our computations are a table of tidal amplitudes, and values of the geopotential coefficients of degrees up to 4 and of other relevant basic Earth parameters. General relations which connect the coefficients of high frequency nutations to those of the equivalent polar motions are established and used for deducing the former. The Chandler resonance plays a significant role in low frequency polar motions. In this context, the role of mantle anelasticity and the nature of the Earth's deformational response to zero frequency forcing are given special consideration. The free core nutation (FCN) resonance of low frequency nutations is shown to affect the prograde semidiurnal nutations through the coupling produced between the nutations in the two frequency bands by triaxiality terms in the angular momenta of the whole Earth and of its fluid core. It is shown in a transparent fashion that the effect of the core triaxiality arises almost exclusively from the huge FCN-related resonance in the wobble of the core. The magnitude of the effect is found to be a few times smaller than reported in a recent paper; it is also found, unlike in that paper, that the changes in the eigenfrequencies due to trixiality are only of the second order in the triaxiality parameter. Numerical results for the polar motions of the nonrigid Earth in

  5. A 3D MR-acquisition scheme for nonrigid bulk motion correction in simultaneous PET-MR

    Energy Technology Data Exchange (ETDEWEB)

    Kolbitsch, Christoph, E-mail: christoph.1.kolbitsch@kcl.ac.uk; Prieto, Claudia; Schaeffter, Tobias [Division of Imaging Sciences and Biomedical Engineering, King' s College London, London SE1 7EH (United Kingdom); Tsoumpas, Charalampos [Division of Imaging Sciences and Biomedical Engineering, King' s College London, London SE1 7EH, United Kingdom and Division of Medical Physics, University of Leeds, Leeds LS2 9JT (United Kingdom)

    2014-08-15

    Purpose: Positron emission tomography (PET) is a highly sensitive medical imaging technique commonly used to detect and assess tumor lesions. Magnetic resonance imaging (MRI) provides high resolution anatomical images with different contrasts and a range of additional information important for cancer diagnosis. Recently, simultaneous PET-MR systems have been released with the promise to provide complementary information from both modalities in a single examination. Due to long scan times, subject nonrigid bulk motion, i.e., changes of the patient's position on the scanner table leading to nonrigid changes of the patient's anatomy, during data acquisition can negatively impair image quality and tracer uptake quantification. A 3D MR-acquisition scheme is proposed to detect and correct for nonrigid bulk motion in simultaneously acquired PET-MR data. Methods: A respiratory navigated three dimensional (3D) MR-acquisition with Radial Phase Encoding (RPE) is used to obtain T1- and T2-weighted data with an isotropic resolution of 1.5 mm. Healthy volunteers are asked to move the abdomen two to three times during data acquisition resulting in overall 19 movements at arbitrary time points. The acquisition scheme is used to retrospectively reconstruct dynamic 3D MR images with different temporal resolutions. Nonrigid bulk motion is detected and corrected in this image data. A simultaneous PET acquisition is simulated and the effect of motion correction is assessed on image quality and standardized uptake values (SUV) for lesions with different diameters. Results: Six respiratory gated 3D data sets with T1- and T2-weighted contrast have been obtained in healthy volunteers. All bulk motion shifts have successfully been detected and motion fields describing the transformation between the different motion states could be obtained with an accuracy of 1.71 ± 0.29 mm. The PET simulation showed errors of up to 67% in measured SUV due to bulk motion which could be reduced to

  6. Validation of a deformable image registration technique for cone beam CT-based dose verification

    Energy Technology Data Exchange (ETDEWEB)

    Moteabbed, M., E-mail: mmoteabbed@partners.org; Sharp, G. C.; Wang, Y.; Trofimov, A.; Efstathiou, J. A.; Lu, H.-M. [Massachusetts General Hospital, Boston, Massachusetts 02114 and Harvard Medical School, Boston, Massachusetts 02115 (United States)

    2015-01-15

    Purpose: As radiation therapy evolves toward more adaptive techniques, image guidance plays an increasingly important role, not only in patient setup but also in monitoring the delivered dose and adapting the treatment to patient changes. This study aimed to validate a method for evaluation of delivered intensity modulated radiotherapy (IMRT) dose based on multimodal deformable image registration (DIR) for prostate treatments. Methods: A pelvic phantom was scanned with CT and cone-beam computed tomography (CBCT). Both images were digitally deformed using two realistic patient-based deformation fields. The original CT was then registered to the deformed CBCT resulting in a secondary deformed CT. The registration quality was assessed as the ability of the DIR method to recover the artificially induced deformations. The primary and secondary deformed CT images as well as vector fields were compared to evaluate the efficacy of the registration method and it’s suitability to be used for dose calculation. PLASTIMATCH, a free and open source software was used for deformable image registration. A B-spline algorithm with optimized parameters was used to achieve the best registration quality. Geometric image evaluation was performed through voxel-based Hounsfield unit (HU) and vector field comparison. For dosimetric evaluation, IMRT treatment plans were created and optimized on the original CT image and recomputed on the two warped images to be compared. The dose volume histograms were compared for the warped structures that were identical in both warped images. This procedure was repeated for the phantom with full, half full, and empty bladder. Results: The results indicated mean HU differences of up to 120 between registered and ground-truth deformed CT images. However, when the CBCT intensities were calibrated using a region of interest (ROI)-based calibration curve, these differences were reduced by up to 60%. Similarly, the mean differences in average vector field

  7. A study of attitude control concepts for precision-pointing non-rigid spacecraft

    Science.gov (United States)

    Likins, P. W.

    1975-01-01

    Attitude control concepts for use onboard structurally nonrigid spacecraft that must be pointed with great precision are examined. The task of determining the eigenproperties of a system of linear time-invariant equations (in terms of hybrid coordinates) representing the attitude motion of a flexible spacecraft is discussed. Literal characteristics are developed for the associated eigenvalues and eigenvectors of the system. A method is presented for determining the poles and zeros of the transfer function describing the attitude dynamics of a flexible spacecraft characterized by hybrid coordinate equations. Alterations are made to linear regulator and observer theory to accommodate modeling errors. The results show that a model error vector, which evolves from an error system, can be added to a reduced system model, estimated by an observer, and used by the control law to render the system less sensitive to uncertain magnitudes and phase relations of truncated modes and external disturbance effects. A hybrid coordinate formulation using the provided assumed mode shapes, rather than incorporating the usual finite element approach is provided.

  8. Deformable Image Registration for Adaptive Radiation Therapy of Head and Neck Cancer: Accuracy and Precision in the Presence of Tumor Changes

    Energy Technology Data Exchange (ETDEWEB)

    Mencarelli, Angelo, E-mail: a.mencarelli@nki.nl [Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam (Netherlands); Kranen, Simon Robert van; Hamming-Vrieze, Olga; Beek, Suzanne van [Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam (Netherlands); Nico Rasch, Coenraad Robert [Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam (Netherlands); Department of Radiation Oncology, Amsterdam Medical Centre, Amsterdam (Netherlands); Herk, Marcel van; Sonke, Jan-Jakob [Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam (Netherlands)

    2014-11-01

    Purpose: To compare deformable image registration (DIR) accuracy and precision for normal and tumor tissues in head and neck cancer patients during the course of radiation therapy (RT). Methods and Materials: Thirteen patients with oropharyngeal tumors, who underwent submucosal implantation of small gold markers (average 6, range 4-10) around the tumor and were treated with RT were retrospectively selected. Two observers identified 15 anatomical features (landmarks) representative of normal tissues in the planning computed tomography (pCT) scan and in weekly cone beam CTs (CBCTs). Gold markers were digitally removed after semiautomatic identification in pCTs and CBCTs. Subsequently, landmarks and gold markers on pCT were propagated to CBCTs, using a b-spline-based DIR and, for comparison, rigid registration (RR). To account for observer variability, the pair-wise difference analysis of variance method was applied. DIR accuracy (systematic error) and precision (random error) for landmarks and gold markers were quantified. Time trend of the precisions for RR and DIR over the weekly CBCTs were evaluated. Results: DIR accuracies were submillimeter and similar for normal and tumor tissue. DIR precision (1 SD) on the other hand was significantly different (P<.01), with 2.2 mm vector length in normal tissue versus 3.3 mm in tumor tissue. No significant time trend in DIR precision was found for normal tissue, whereas in tumor, DIR precision was significantly (P<.009) degraded during the course of treatment by 0.21 mm/week. Conclusions: DIR for tumor registration proved to be less precise than that for normal tissues due to limited contrast and complex non-elastic tumor response. Caution should therefore be exercised when applying DIR for tumor changes in adaptive procedures.

  9. The Household Registration System

    Directory of Open Access Journals (Sweden)

    2000-06-01

    Full Text Available Although longitudinal experimental community health research is crucial to testing hypotheses about the demographic impact of health technologies, longitudinal demographic research field stations are rare, owing to the complexity and high cost of developing requisite computer software systems. This paper describes the Household Registration System (HRS, a software package that has been used for the rapid development of eleven surveillance systems in sub-Saharan Africa and Asia. Features of the HRS automate software generation for a family of surveillance applications, obviating the need for new and complex computer software systems for each new longitudinal demographic study.

  10. Registration Summer Camp 2016

    CERN Multimedia

    2016-01-01

    Reminder: registration for the CERN Staff Association Summer Camp is now open for children from 4 to 6 years old.   More information on the website: http://nurseryschool.web.cern.ch/. The summer camp is open to all children. The proposed cost is 480.-CHF/week, lunch included. The camp will be open weeks 27, 28, 29 and 30, from 8:30 a.m. to 5:30 p.m. For further questions, you are welcome to contact us by email at Summer.Camp@cern.ch. CERN Staff Association

  11. 40 CFR 155.50 - Initiate a pesticide's registration review.

    Science.gov (United States)

    2010-07-01

    ...) PESTICIDE PROGRAMS REGISTRATION STANDARDS AND REGISTRATION REVIEW Registration Review Procedures § 155.50... documents; (4) Bibliographies concerning current registrations; (5) Summaries of incident data; and (6)...

  12. A multiple-image-based method to evaluate the performance of deformable image registration in the pelvis

    Science.gov (United States)

    Saleh, Ziad; Thor, Maria; Apte, Aditya P.; Sharp, Gregory; Tang, Xiaoli; Veeraraghavan, Harini; Muren, Ludvig; Deasy, Joseph

    2016-08-01

    Deformable image registration (DIR) is essential for adaptive radiotherapy (RT) for tumor sites subject to motion, changes in tumor volume, as well as changes in patient normal anatomy due to weight loss. Several methods have been published to evaluate DIR-related uncertainties but they are not widely adopted. The aim of this study was, therefore, to evaluate intra-patient DIR for two highly deformable organs—the bladder and the rectum—in prostate cancer RT using a quantitative metric based on multiple image registration, the distance discordance metric (DDM). Voxel-by-voxel DIR uncertainties of the bladder and rectum were evaluated using DDM on weekly CT scans of 38 subjects previously treated with RT for prostate cancer (six scans/subject). The DDM was obtained from group-wise B-spline registration of each patient’s collection of repeat CT scans. For each structure, registration uncertainties were derived from DDM-related metrics. In addition, five other quantitative measures, including inverse consistency error (ICE), transitivity error (TE), Dice similarity (DSC) and volume ratios between corresponding structures from pre- and post- registered images were computed and compared with the DDM. The DDM varied across subjects and structures; DDMmean of the bladder ranged from 2 to 13 mm and from 1 to 11 mm for the rectum. There was a high correlation between DDMmean of the bladder and the rectum (Pearson’s correlation coefficient, R p  =  0.62). The correlation between DDMmean and the volume ratios post-DIR was stronger (R p  =  0.51 0.68) than the correlation with the TE (bladder: R p  =  0.46 rectum: R p  =  0.47), or the ICE (bladder: R p  =  0.34 rectum: R p  =  0.37). There was a negative correlation between DSC and DDMmean of both the bladder (R p  =  -0.23) and the rectum (R p  =  -0.63). The DDM uncertainty metric indicated considerable DIR variability across subjects and structures

  13. A non-rigid point matching method with local topology preservation for accurate bladder dose summation in high dose rate cervical brachytherapy

    Science.gov (United States)

    Chen, Haibin; Zhong, Zichun; Liao, Yuliang; Pompoš, Arnold; Hrycushko, Brian; Albuquerque, Kevin; Zhen, Xin; Zhou, Linghong; Gu, Xuejun

    2016-02-01

    GEC-ESTRO guidelines for high dose rate cervical brachytherapy advocate the reporting of the D2cc (the minimum dose received by the maximally exposed 2cc volume) to organs at risk. Due to large interfractional organ motion, reporting of accurate cumulative D2cc over a multifractional course is a non-trivial task requiring deformable image registration and deformable dose summation. To efficiently and accurately describe the point-to-point correspondence of the bladder wall over all treatment fractions while preserving local topologies, we propose a novel graphic processing unit (GPU)-based non-rigid point matching algorithm. This is achieved by introducing local anatomic information into the iterative update of correspondence matrix computation in the ‘thin plate splines-robust point matching’ (TPS-RPM) scheme. The performance of the GPU-based TPS-RPM with local topology preservation algorithm (TPS-RPM-LTP) was evaluated using four numerically simulated synthetic bladders having known deformations, a custom-made porcine bladder phantom embedded with twenty one fiducial markers, and 29 fractional computed tomography (CT) images from seven cervical cancer patients. Results show that TPS-RPM-LTP achieved excellent geometric accuracy with landmark residual distance error (RDE) of 0.7  ±  0.3 mm for the numerical synthetic data with different scales of bladder deformation and structure complexity, and 3.7  ±  1.8 mm and 1.6  ±  0.8 mm for the porcine bladder phantom with large and small deformation, respectively. The RDE accuracy of the urethral orifice landmarks in patient bladders was 3.7  ±  2.1 mm. When compared to the original TPS-RPM, the TPS-RPM-LTP improved landmark matching by reducing landmark RDE by 50  ±  19%, 37  ±  11% and 28  ±  11% for the synthetic, porcine phantom and the patient bladders, respectively. This was achieved with a computational time of less than 15 s in all cases

  14. Design and optimization of transplanting mechanism with B-spline non-circular planet gear train for rice pot seedling%B样条非圆齿轮行星轮系水稻钵苗移栽机构的设计与优化

    Institute of Scientific and Technical Information of China (English)

    左彦军; 曹鹏; 赵匀; 于晓旭; 吕程; 张智超; 张昊

    2014-01-01

    the above problems, the paper adopted the cubic non-uniform rational B-spline curve theory to fit non-circular gear pitch curve with coincidence of first and last data points as a closed curve. The shape of non-circular gear pitch curve was controlled and expressed through selecting the 13 data points, a new rotary planet gear train mechanism with non-circular gear was developed for rice pot seedling transplants. Through the kinematic analysis of the mechanism, the attitude and sharp point trajectory objective functions of seedling clip were built and transformed into the optimization mathematics model based on optimization of target determined. A computer aided analysis and optimization software of the transplanting mechanism with non-circular planet gear train for rice pot seedling was developed on the MATLAB GUI platform. Through adjusting data points by the man-machine interaction, the attitude and sharp point trajectory of seedling clip were optimized, and a set of structural parameters were obtained to meet the requirements of the rice pot seedling transplants. A three dimensional model was built in software of UG 8.0, and input to software of Admas 2010. The simulation results show that, both track results of theoretical analysis and virtual prototype experiment are fundamentally consistent, so the correctness of the kinematics mathematical model was verified by the virtual experiment. The research can provide a theoretical basis for developing transplanting mechanisms for rice pot seedling.

  15. Contour Propagation With Riemannian Elasticity Regularization

    DEFF Research Database (Denmark)

    Bjerre, Troels; Hansen, Mads Fogtmann; Sapru, W.;

    2011-01-01

    guided corrections. This study compares manual delineations in replanning CT scans of head-and-neck patients to automatic contour propagation using deformable registration with Riemannian regularization. The potential benefit of locally assigned regularization parameters according to tissue type...... the planning CT onto the rescans and correcting to reflect actual anatomical changes. For deformable registration, a free-form, multi-level, B-spline deformation model with Riemannian elasticity, penalizing non-rigid local deformations, and volumetric changes, was used. Regularization parameters was defined...... regularization parameters was performed. For each replanning scan, the volume of the manually delineated and automatically propagated GTV was determined and Dice’s coefficient was calculated between segmentations from the propagated contours and manual delineations. Results: The replanning segmentations showed...

  16. Multi-dimensional respiratory motion tracking from markerless optical surface imaging based on deformable mesh registration

    International Nuclear Information System (INIS)

    Real-time optical surface imaging systems offer a non-invasive way to monitor intra-fraction motion of a patient's thorax surface during radiotherapy treatments. Due to lack of point correspondence in dynamic surface acquisition, such systems cannot currently provide 3D motion tracking at specific surface landmarks, as available in optical technologies based on passive markers. We propose to apply deformable mesh registration to extract surface point trajectories from markerless optical imaging, thus yielding multi-dimensional breathing traces. The investigated approach is based on a non-rigid extension of the iterative closest point algorithm, using a locally affine regularization. The accuracy in tracking breathing motion was quantified in a group of healthy volunteers, by pair-wise registering the thoraco-abdominal surfaces acquired at three different respiratory phases using a clinically available optical system. The motion tracking accuracy proved to be maximal in the abdominal region, where breathing motion mostly occurs, with average errors of 1.09 mm. The results demonstrate the feasibility of recovering multi-dimensional breathing motion from markerless optical surface acquisitions by using the implemented deformable registration algorithm. The approach can potentially improve respiratory motion management in radiation therapy, including motion artefact reduction or tumour motion compensation by means of internal/external correlation models. (paper)

  17. SU-E-J-159: Intra-Patient Deformable Image Registration Uncertainties Quantified Using the Distance Discordance Metric

    Energy Technology Data Exchange (ETDEWEB)

    Saleh, Z; Thor, M; Apte, A; Deasy, J [Memorial Sloan Kettering Cancer Center, NY City, NY (United States); Sharp, G [Massachusetts General Hospital, Boston, MA (United States); Muren, L [Aarhus University Hospital, Aarhus (Denmark)

    2014-06-01

    Purpose: The quantitative evaluation of deformable image registration (DIR) is currently challenging due to lack of a ground truth. In this study we test a new method proposed for quantifying multiple-image based DIRrelated uncertainties, for DIR of pelvic images. Methods: 19 patients were analyzed, each with 6 CT scans, who previously had radiotherapy for prostate cancer. Manually delineated structures for rectum and bladder, which served as ground truth structures, were delineated on the planning CT and each subsequent scan. For each patient, voxel-by-voxel DIR-related uncertainties were evaluated, following B-spline based DIR, by applying a previously developed metric, the distance discordance metric (DDM; Saleh et al., PMB (2014) 59:733). The DDM map was superimposed on the first acquired CT scan and DDM statistics were assessed, also relative to two metrics estimating the agreement between the propagated and the manually delineated structures. Results: The highest DDM values which correspond to greatest spatial uncertainties were observed near the body surface and in the bowel due to the presence of gas. The mean rectal and bladder DDM values ranged from 1.1–11.1 mm and 1.5–12.7 mm, respectively. There was a strong correlation in the DDMs between the rectum and bladder (Pearson R = 0.68 for the max DDM). For both structures, DDM was correlated with the ratio between the DIR-propagated and manually delineated volumes (R = 0.74 for the max rectal DDM). The maximum rectal DDM was negatively correlated with the Dice Similarity Coefficient between the propagated and the manually delineated volumes (R= −0.52). Conclusion: The multipleimage based DDM map quantified considerable DIR variability across different structures and among patients. Besides using the DDM for quantifying DIR-related uncertainties it could potentially be used to adjust for uncertainties in DIR-based accumulated dose distributions.

  18. Detailed analysis of the density change on chest CT of COPD using non-rigid registration of inspiration/expiration CT scans

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun Young [Chonbuk National University Medical School and Hospital, Research Institute of Clinical Medicine, Department of Radiology, Jeollabuk-do (Korea, Republic of); University of Ulsan College of Medicine, Asan Medical Center, Department of Radiology and Research Institute of Radiology, Seoul (Korea, Republic of); Seo, Joon Beom; Lee, Hyun Joo; Kim, Namkug; Lee, Eunsol; Lee, Sang Min; Oh, Sang Young [University of Ulsan College of Medicine, Asan Medical Center, Department of Radiology and Research Institute of Radiology, Seoul (Korea, Republic of); Hwang, Hye Jeon [Hallym University Sacred Heart Hospital, Department of Radiology, Hallym University College of Medicine, Gyeonggi-do (Korea, Republic of); Oh, Yeon-Mok; Lee, Sang-Do [University of Ulsan College of Medicine, Asan Medical Center, Department of Pulmonary and Critical Care Medicine, and Clinical Research Center for Chronic Obstructive Airway Diseases, Seoul (Korea, Republic of)

    2014-09-14

    One objective was to evaluate the air trapping index (ATI), measured by inspiration/expiration CT, in COPD patients and nonsmokers. Another objective was to assess the association between the pulmonary function test (PFT) and CT parameters such as ATI or other indices, separately in the whole lung, in emphysema, and in hyperinflated and normal lung areas. One hundred and thirty-eight COPD patients and 29 nonsmokers were included in our study. The ATI, the emphysema index (EI), the gas trapping index (Exp -856) and expiration/inspiration ratio of mean lung density (E/Iratio of MLD) were measured on CT. The values of the whole lung, of emphysema, and of hyperinflated and normal lung areas were compared and then correlated with various PFT parameters. Compared with nonsmokers, COPD patients showed a higher ATI in the whole lung and in each lung lesion (all P < 0.05). The ATI showed a higher correlation than EI with FEF{sub 25-75%}, RV and RV/TLC, and was comparable to Exp -856 and the E/I ratio of MLD. The ATI of emphysema and hyperinflated areas on CT showed better correlation than the normal lung area with PFT parameters. Detailed analysis of density change at inspiration and expiration CT of COPD can provide new insights into pulmonary functional impairment in each lung area. (orig.)

  19. Detailed analysis of the density change on chest CT of COPD using non-rigid registration of inspiration/expiration CT scans

    International Nuclear Information System (INIS)

    One objective was to evaluate the air trapping index (ATI), measured by inspiration/expiration CT, in COPD patients and nonsmokers. Another objective was to assess the association between the pulmonary function test (PFT) and CT parameters such as ATI or other indices, separately in the whole lung, in emphysema, and in hyperinflated and normal lung areas. One hundred and thirty-eight COPD patients and 29 nonsmokers were included in our study. The ATI, the emphysema index (EI), the gas trapping index (Exp -856) and expiration/inspiration ratio of mean lung density (E/Iratio of MLD) were measured on CT. The values of the whole lung, of emphysema, and of hyperinflated and normal lung areas were compared and then correlated with various PFT parameters. Compared with nonsmokers, COPD patients showed a higher ATI in the whole lung and in each lung lesion (all P 25-75%, RV and RV/TLC, and was comparable to Exp -856 and the E/I ratio of MLD. The ATI of emphysema and hyperinflated areas on CT showed better correlation than the normal lung area with PFT parameters. Detailed analysis of density change at inspiration and expiration CT of COPD can provide new insights into pulmonary functional impairment in each lung area. (orig.)

  20. Non-Rigid Registration with Simultaneously Matched Intensity and Shape%灰度与形状同步匹配的非刚性配准研究

    Institute of Scientific and Technical Information of China (English)

    林相波; 邱天爽; 阮素; Frédéric Nicolier

    2009-01-01

    基于灰度的非刚性配准算法一般假设参考图像和浮动图像对应结构之间的灰度保持一致,然而在基于图谱的图像配准应用中,这种假设往往不符合实际.本文在给出一种可以同时校正灰度和形状差异的弹性配准算法的同时,针对该算法不能校正局部微小形变的弱点,提出采用自由项变换的方法进行校正以提高配准精度.配准实验基于20个IBSR真实脑部MRI图像,结果表明配准后图像与参考图像间的互相关系数得到明显提高.实验证明,本文提出的方法不仅能够同时校正形状差异和灰度变化,而且具有较高的配准质量.

  1. Computer Registration Becoming Mandatory

    CERN Multimedia

    2003-01-01

    Following the decision by the CERN Management Board (see Weekly Bulletin 38/2003), registration of all computers connected to CERN's network will be enforced and only registered computers will be allowed network access. The implementation has started with the IT buildings, continues with building 40 and the Prevessin site (as of Tuesday 4th November 2003), and will cover the whole of CERN before the end of this year. We therefore recommend strongly that you register all your computers in CERN's network database including all network access cards (Ethernet AND wireless) as soon as possible without waiting for the access restriction to take force. This will allow you accessing the network without interruption and help IT service providers to contact you in case of problems (e.g. security problems, viruses, etc.) Users WITH a CERN computing account register at: http://cern.ch/register/ (CERN Intranet page) Visitors WITHOUT a CERN computing account (e.g. short term visitors) register at: http://cern.ch/regis...

  2. Computer Registration Becoming Mandatory

    CERN Multimedia

    2003-01-01

    Following the decision by the CERN Management Board (see Weekly Bulletin 38/2003), registration of all computers connected to CERN's network will be enforced and only registered computers will be allowed network access. The implementation has started with the IT buildings, continues with building 40 and the Prevessin site (as of Tuesday 4th November 2003), and will cover the whole of CERN before the end of this year. We therefore recommend strongly that you register all your computers in CERN's network database (Ethernet and wire-less cards) as soon as possible without waiting for the access restriction to take force. This will allow you accessing the network without interruption and help IT service providers to contact you in case of problems (security problems, viruses, etc.) • Users WITH a CERN computing account register at: http://cern.ch/register/ (CERN Intranet page) • Visitors WITHOUT a CERN computing account (e.g. short term visitors) register at: http://cern.ch/registerVisitorComp...

  3. Drug Establishments Current Registration Site

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Drug Establishments Current Registration Site (DECRS) is a database of current information submitted by drug firms to register establishments (facilities) which...

  4. Online Registration System

    Directory of Open Access Journals (Sweden)

    Ala'a M. Al-Shaikh

    2010-08-01

    Full Text Available Problem Statement: Enrolling students into the General Associate-DegreeExaminations is a very difficult, critical, and important process. Students arerequired to pass this exam in Jordan to be given the Associate Degree in thefiled of study they studied for 2 years. The exam is held 3 times per annum;annually, more than 15,000 students from different colleges all over thecountry apply to the exam. Managing all exam activities is a very complex andsophisticated process. In the old, conventional method, i.e. the manualregistration system, communication between different parties working withexam activities is very difficult. Lack of technologies used in exam activitiesobstructs dealing with it in a modern and simplified way. Approach: The mainoutcome is to computerize everything related to the General Associate-Degree Examination. To do so, the Waterfall Model is to be used to study thenew system requirements, analyze it, design, implement, and finally test anddeploy it. Results: After the deployment of the new system and working with it,all the problems referred to were solved; this is done by adopting the OnlineRegistration System which helped a lot in reducing the errors resulted indifferent ways and which in turn afferent the correctness of the exam itself.Conclusion/Recommendation: In conclusion a web-based tool was developedto computerize the required steps already expected by the system. As afurther work, some features might be added, such as adding SMS support,adding AJAX functionality to the website to increase response time, and tocreate a bulletin board system, that might enable different parties working withthe system to interact and communicate with each other easily.

  5. Efficient Hyperelastic Regularization for Registration

    DEFF Research Database (Denmark)

    Darkner, Sune; Hansen, Michael S; Larsen, Rasmus;

    2011-01-01

    For most image registration problems a smooth one-to-one mapping is desirable, a diffeomorphism. This can be obtained using priors such as volume preservation, certain kinds of elasticity or both. The key principle is to regularize the strain of the deformation which can be done through penalizat......For most image registration problems a smooth one-to-one mapping is desirable, a diffeomorphism. This can be obtained using priors such as volume preservation, certain kinds of elasticity or both. The key principle is to regularize the strain of the deformation which can be done through...... penalization of the eigen values of the stress tensor. We present a computational framework for regularization of image registration for isotropic hyper elasticity. We formulate an efficient and parallel scheme for computing the principal stain based for a given parameterization by decomposing the left Cauchy...... elastic priors such at the Saint Vernant Kirchoff model, the Ogden material model or Riemanian elasticity. We exemplify the approach through synthetic registration and special tests as well as registration of different modalities; 2D cardiac MRI and 3D surfaces of the human ear. The artificial examples...

  6. Mask registration and wafer overlay

    Science.gov (United States)

    Lee, Chulseung; Bang, Changjin; Kim, Myoungsoo; Kang, Hyosang; Lee, Dohwa; Jeong, Woonjae; Lim, Ok-Sung; Yoon, Seunghoon; Jung, Jaekang; Laske, Frank; Parisoli, Lidia; Roeth, Klaus-Dieter; Robinson, John C.; Jug, Sven; Izikson, Pavel; Dinu, Berta; Widmann, Amir; Choi, DongSub

    2010-03-01

    Overlay continues to be one of the key challenges for lithography in advanced semiconductor manufacturing. It becomes even more challenging due to the continued shrinking of the device node. Some low k1 techniques, such as Double Exposure and Double Patterning also add additional loss of the overlay margin due to the fact that the single layer pattern is created based on more than 1 exposure. Therefore, the overlay between 2 exposures requires very tight overlay specification. Mask registration is one of the major contributors to wafer overlay, especially field related overlay. We investigated mask registration and wafer overlay by co-analyzing the mask data and the wafer overlay data. To achieve the accurate cohesive results, we introduced the combined metrology mark which can be used for both mask registration measurement as well as for wafer overlay measurement. Coincidence of both metrology marks make it possible to subtract mask signature from wafer overlay without compromising the accuracy due to the physical distance between measurement marks, if we use 2 different marks for both metrologies. Therefore, it is possible to extract pure scanner related signatures, and to analyze the scanner related signatures in details to in order to enable root cause analysis and ultimately drive higher wafer yield. We determined the exact mask registration error in order to decompose wafer overlay into mask, scanner, process and metrology. We also studied the impact of pellicle mounting by comparison of mask registration measurement pre-pellicle mounting and post-pellicle mounting in this investigation.

  7. SU-E-J-107: The Impact of the Tumor Location to Deformable Image Registration

    Energy Technology Data Exchange (ETDEWEB)

    Sugawara, Y [The National Center for Global Health and Medicine, Shinjuku-ku, Tokyo (Japan); Tohoku University School of Medicine, Sendai, Miyagi (Japan); Tachibana, H [National Cancer Center Hospital East, Kashiwa, Chiba (Japan); Kadoya, N; Jingu, K [Tohoku University School of Medicine, Sendai, Miyagi (Japan); Kitamura, N [The Cancer Institute Hospital, JPese Foundation for Cancer Research, Koutou-ku, Tokyo (Japan)

    2015-06-15

    Purpose: For four-dimensional planning and adaptive radiotherapy, the accuracy of deformable image registration (DIR) is essential. We evaluated the accuracy of an in-house program with the free-downloadable DIR software library package (NiftyReg) and two commercially available DIR software programs (MIM Maestro and Velocity AI) in lung SBRT cancer patients. In addition to it, the relationship between the tumor location and the accuracy of the DIRs was investigated. Methods: The free-form deformation was implemented in the in-house program and the MIM. The Velocity was based on the B-spline algorithm. The accuracy of the three programs was evaluated in comparison for the structures on 4DCT image datasets between at the peak-inhale and at the peak-exhale. The dice similarity coefficient (DSC) and normalized DSC (NDSC) were measured for the gross tumor volumes from 19 lung SBRT patients. Results: The DSC measurement showed the median values of the DSC were 0.885, 0.872 and 0.798 for the In-house program, the MIM and the Velocity, respectively. The Velocity showed significant difference compared to the others. The median NDSC values were 1.027, 1.005 and 0.946 for the In-house, the MIM and the Velocity, respectively. This indicated that the spatial overlap agreement between the reference and the deformed structure for the in-house and MIM was comparable with the accuracy within 1mm uncertainty. There was larger discrepancy within 1–2mm uncertainty for the Velocity. The In-house and the MIM showed the higher NDSC values than the median values when the GTV was not attached to the chest wall and diaphragm(p < 0.05). However, there is no relationship between the accuracy and the tumor location in the Velocity. Conclusion: The difference of the DIR program would affect different accuracy and the accuracy may be reduced when the tumor is located or attached to chest wall or diaphragm.

  8. Continental deformation accommodated by non-rigid passive bookshelf faulting: An example from the Cenozoic tectonic development of northern Tibet

    Science.gov (United States)

    Zuza, Andrew V.; Yin, An

    2016-05-01

    Collision-induced continental deformation commonly involves complex interactions between strike-slip faulting and off-fault deformation, yet this relationship has rarely been quantified. In northern Tibet, Cenozoic deformation is expressed by the development of the > 1000-km-long east-striking left-slip Kunlun, Qinling, and Haiyuan faults. Each have a maximum slip in the central fault segment exceeding 10s to ~ 100 km but a much smaller slip magnitude (~plate-like rigid-body motion and flow-like distributed deformation end-member models for continental tectonics. Here we propose a non-rigid bookshelf-fault model for the Cenozoic tectonic development of northern Tibet. Our model, quantitatively relating discrete left-slip faulting to distributed off-fault deformation during regional clockwise rotation, explains several puzzling features, including the: (1) clockwise rotation of east-striking left-slip faults against the northeast-striking left-slip Altyn Tagh fault along the northwestern margin of the Tibetan Plateau, (2) alternating fault-parallel extension and shortening in the off-fault regions, and (3) eastward-tapering map-view geometries of the Qimen Tagh, Qaidam, and Qilian Shan thrust belts that link with the three major left-slip faults in northern Tibet. We refer to this specific non-rigid bookshelf-fault system as a passive bookshelf-fault system because the rotating bookshelf panels are detached from the rigid bounding domains. As a consequence, the wallrock of the strike-slip faults deforms to accommodate both the clockwise rotation of the left-slip faults and off-fault strain that arises at the fault ends. An important implication of our model is that the style and magnitude of Cenozoic deformation in northern Tibet vary considerably in the east-west direction. Thus, any single north-south cross section and its kinematic reconstruction through the region do not properly quantify the complex deformational processes of plateau formation.

  9. Efficient Hyperelastic Regularization for Registration

    DEFF Research Database (Denmark)

    Darkner, Sune; Hansen, Michael Sass; Larsen, Rasmus;

    2011-01-01

    For most image registration problems a smooth one-to-one mapping is desirable, a diffeomorphism. This can be obtained using priors such as volume preservation, certain kinds of elasticity or both. The key principle is to regularize the strain of the deformation which can be done through penalizat......For most image registration problems a smooth one-to-one mapping is desirable, a diffeomorphism. This can be obtained using priors such as volume preservation, certain kinds of elasticity or both. The key principle is to regularize the strain of the deformation which can be done through...... penalization of the eigen values of the stress tensor. We present a computational framework for regularization of image registration for isotropic hyper elasticity. We formulate an efficient and parallel scheme for computing the principal stain based for a given parameterization by decomposing the left Cauchy...

  10. Radar image registration and rectification

    Science.gov (United States)

    Naraghi, M.; Stromberg, W. D.

    1983-01-01

    Two techniques for radar image registration and rectification are presented. In the registration method, a general 2-D polynomial transform is defined to accomplish the geometric mapping from one image into the other. The degree and coefficients of the polynomial are obtained using an a priori found tiepoint data set. In the second part of the paper, a rectification procedure is developed that models the distortion present in the radar image in terms of the radar sensor's platform parameters and the topographic variations of the imaged scene. This model, the ephemeris data and the digital topographic data are then used in rectifying the radar image. The two techniques are then used in registering and rectifying two examples of radar imagery. Each method is discussed as to its benefits, shortcomings and registration accuracy.

  11. Language proficiency and nursing registration.

    Science.gov (United States)

    Müller, Amanda

    2016-02-01

    This discussion paper focuses on English proficiency standards for nursing registration in Australia, how Australia has dealt with the issue of language proficiency, and the factors which have led to the establishment of the current language standards. Also, this paper will provide a comparison of the two language tests that are currently accepted in Australia (OET and IELTS), including the appropriateness of these tests and the minimum standards used. The paper will also examine the use of educational background as an indicator of language proficiency. Finally, communication-based complaints in the post-registration environment will be explored, and some discussion will be provided about why pre-registration measures might have failed to prevent such problematic situations from occurring. PMID:25704372

  12. Language proficiency and nursing registration.

    Science.gov (United States)

    Müller, Amanda

    2016-02-01

    This discussion paper focuses on English proficiency standards for nursing registration in Australia, how Australia has dealt with the issue of language proficiency, and the factors which have led to the establishment of the current language standards. Also, this paper will provide a comparison of the two language tests that are currently accepted in Australia (OET and IELTS), including the appropriateness of these tests and the minimum standards used. The paper will also examine the use of educational background as an indicator of language proficiency. Finally, communication-based complaints in the post-registration environment will be explored, and some discussion will be provided about why pre-registration measures might have failed to prevent such problematic situations from occurring.

  13. A complete software application for automatic registration of x-ray mammography and magnetic resonance images

    Energy Technology Data Exchange (ETDEWEB)

    Solves-Llorens, J. A.; Rupérez, M. J., E-mail: mjruperez@labhuman.i3bh.es; Monserrat, C. [LabHuman, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia (Spain); Feliu, E.; García, M. [Hospital Clínica Benidorm, Avda. Alfonso Puchades, 8, 03501 Benidorm (Alicante) (Spain); Lloret, M. [Hospital Universitari y Politècnic La Fe, Bulevar Sur, 46026 Valencia (Spain)

    2014-08-15

    Purpose: This work presents a complete and automatic software application to aid radiologists in breast cancer diagnosis. The application is a fully automated method that performs a complete registration of magnetic resonance (MR) images and x-ray (XR) images in both directions (from MR to XR and from XR to MR) and for both x-ray mammograms, craniocaudal (CC), and mediolateral oblique (MLO). This new approximation allows radiologists to mark points in the MR images and, without any manual intervention, it provides their corresponding points in both types of XR mammograms and vice versa. Methods: The application automatically segments magnetic resonance images and x-ray images using the C-Means method and the Otsu method, respectively. It compresses the magnetic resonance images in both directions, CC and MLO, using a biomechanical model of the breast that distinguishes the specific biomechanical behavior of each one of its three tissues (skin, fat, and glandular tissue) separately. It makes a projection of both compressions and registers them with the original XR images using affine transformations and nonrigid registration methods. Results: The application has been validated by two expert radiologists. This was carried out through a quantitative validation on 14 data sets in which the Euclidean distance between points marked by the radiologists and the corresponding points obtained by the application were measured. The results showed a mean error of 4.2 ± 1.9 mm for the MRI to CC registration, 4.8 ± 1.3 mm for the MRI to MLO registration, and 4.1 ± 1.3 mm for the CC and MLO to MRI registration. Conclusions: A complete software application that automatically registers XR and MR images of the breast has been implemented. The application permits radiologists to estimate the position of a lesion that is suspected of being a tumor in an imaging modality based on its position in another different modality with a clinically acceptable error. The results show that the

  14. Digitale kort og administrative registre

    DEFF Research Database (Denmark)

    Hansen, H. S.; Skov-Petersen, H.

    Rapporten indeholder dels en beskrivelse af de vigtigste nationale databaser med stedfæstet information og dels en vejledning i sammenstilling imellem digitale kort og administrative registre. Rapportens første del beskriver de enkelte databaser med hensyn til bl.a. adgangsforhold, indhold og...... nøgler, hvoraf sidstnævnte spiller en afgørende rolle i forbindelse med sammenstilling af digitale kort og administrative registre. Rapportens anden del fokuserer på praktiske forsøg med sammenstilling af digitale kort og administrative register. Der gives anvisninger på sammenstilling af Bygnings- og...

  15. Inter-slice bidirectional registration-based segmentation of the prostate gland in MR and CT image sequences

    Energy Technology Data Exchange (ETDEWEB)

    Khalvati, Farzad, E-mail: farzad.khalvati@uwaterloo.ca; Tizhoosh, Hamid R. [Department of Systems Design Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Salmanpour, Aryan; Rahnamayan, Shahryar [Department of Engineering and Applied Science, University of Ontario Institute of Technology, Oshawa, Ontario L1H 7K4 (Canada); Rodrigues, George [Department of Radiation Oncology, London Regional Cancer Program, London, Ontario N6C 2R6, Canada and Department of Epidemiology/Biostatistics, University of Western Ontario, London, Ontario N6A 3K7 (Canada)

    2013-12-15

    Purpose: Accurate segmentation and volume estimation of the prostate gland in magnetic resonance (MR) and computed tomography (CT) images are necessary steps in diagnosis, treatment, and monitoring of prostate cancer. This paper presents an algorithm for the prostate gland volume estimation based on the semiautomated segmentation of individual slices in T2-weighted MR and CT image sequences. Methods: The proposedInter-Slice Bidirectional Registration-based Segmentation (iBRS) algorithm relies on interslice image registration of volume data to segment the prostate gland without the use of an anatomical atlas. It requires the user to mark only three slices in a given volume dataset, i.e., the first, middle, and last slices. Next, the proposed algorithm uses a registration algorithm to autosegment the remaining slices. We conducted comprehensive experiments to measure the performance of the proposed algorithm using three registration methods (i.e., rigid, affine, and nonrigid techniques). Results: The results with the proposed technique were compared with manual marking using prostate MR and CT images from 117 patients. Manual marking was performed by an expert user for all 117 patients. The median accuracies for individual slices measured using the Dice similarity coefficient (DSC) were 92% and 91% for MR and CT images, respectively. The iBRS algorithm was also evaluated regarding user variability, which confirmed that the algorithm was robust to interuser variability when marking the prostate gland. Conclusions: The proposed algorithm exploits the interslice data redundancy of the images in a volume dataset of MR and CT images and eliminates the need for an atlas, minimizing the computational cost while producing highly accurate results which are robust to interuser variability.

  16. SU-C-17A-03: Evaluation of Deformable Image Registration Methods Between MRI and CT for Prostate Cancer Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Wen, N; Glide-Hurst, C; Zhong, H; Chin, K; Kumarasiri, A; Liu, C; Liu, M; Siddiqui, S [I Chetty, Henry Ford Health System, Detroit, MI (United States)

    2014-06-15

    Purpose: We evaluated the performance of two commercially available and one open source B-Spline deformable image registration (DIR) algorithms between T2-weighted MRI and treatment planning CT using the DICE indices. Methods: CT simulation (CT-SIM) and MR simulation (MR-SIM) for four prostate cancer patients were conducted on the same day using the same setup and immobilization devices. CT images (120 kVp, 500 mAs, voxel size = 1.1x1.1x3.0 mm3) were acquired using an open-bore CT scanner. T2-weighted Turbo Spine Echo (T2W-TSE) images (TE/TR/α = 80/4560 ms/90°, voxel size = 0.7×0.7×2.5 mm3) were scanned on a 1.0T high field open MR-SIM. Prostates, seminal vesicles, rectum and bladders were delineated on both T2W-TSE and CT images by the attending physician. T2W-TSE images were registered to CT images using three DIR algorithms, SmartAdapt (Varian), Velocity AI (Velocity) and Elastix (Klein et al 2010) and contours were propagated. DIR results were evaluated quantitatively or qualitatively by image comparison and calculating organ DICE indices. Results: Significant differences in the contours of prostate and seminal vesicles were observed between MR and CT. On average, volume changes of the propagated contours were 5%, 2%, 160% and 8% for the prostate, seminal vesicles, bladder and rectum respectively. Corresponding mean DICE indices were 0.7, 0.5, 0.8, and 0.7. The intraclass correlation coefficient (ICC) was 0.9 among three algorithms for the Dice indices. Conclusion: Three DIR algorithms for CT/MR registration yielded similar results for organ propagation. Due to the different soft tissue contrasts between MRI and CT, organ delineation of prostate and SVs varied significantly, thus efforts to develop other DIR evaluation metrics are warranted. Conflict of interest: Submitting institution has research agreements with Varian Medical System and Philips Healthcare.

  17. USDA registration and rectification requirements

    Science.gov (United States)

    Allen, R.

    1982-01-01

    Some of the requirements of the United States Department of Agriculture for accuracy of aerospace acquired data, and specifically, requirements for registration and rectification of remotely sensed data are discussed. Particular attention is given to foreign and domestic crop estimation and forecasting, forestry information applications, and rangeland condition evaluations.

  18. Registration of randomized clinical trials

    DEFF Research Database (Denmark)

    Østervig, R M; Sonne, A; Rasmussen, L S

    2015-01-01

    starting enrolment before 2010 to 63.2% after 2010 (24/38, P clinical trials were registered at clinicaltrials.gov. CONCLUSION: Many published randomized controlled trials from Acta Anaesthesiologica Scandinavica were not adequately registered but the requirement of trial registration has...

  19. What drives Users' Website Registration?

    NARCIS (Netherlands)

    T. Li (Ting); P.A. Pavlou (Paul)

    2013-01-01

    textabstractUser registration is an important prerequisite for the success of many websites by enabling users to gain access to domain information and personalized content. It is not always desirable for users, however, because they need to disclose personal information. This paper examines what dri

  20. Noise estimation in infrared image sequences: a tool for the quantitative evaluation of the effectiveness of registration algorithms.

    Science.gov (United States)

    Agostini, Valentina; Delsanto, Silvia; Knaflitz, Marco; Molinari, Filippo

    2008-07-01

    Dynamic infrared imaging has been proposed in literature as an adjunctive technique to mammography in breast cancer diagnosis. It is based on the acquisition of hundreds of consecutive thermal images with a frame rate ranging from 50 to 200 frames/s, followed by the harmonic analysis of temperature time series at each image pixel. However, the temperature fluctuation due to blood perfusion, which is the signal of interest, is small compared to the signal fluctuation due to subject movements. Hence, before extracting the time series describing temperature fluctuations, it is fundamental to realign the thermal images to attenuate motion artifacts. In this paper, we describe a method for the quantitative evaluation of any kind of feature-based registration algorithm on thermal image sequences, provided that an estimation of local velocities of reference points on the skin is available. As an example of evaluation of a registration algorithm, we report the evaluation of the SNR improvement obtained by applying a nonrigid piecewise linear algorithm.

  1. Craniofacial statistical deformation models of wild-type mice and Crouzon mice

    Science.gov (United States)

    Ólafsdóttir, Hildur; Darvann, Tron A.; Ersbøll, Bjarne K.; Hermann, Nuno V.; Oubel, Estanislao; Larsen, Rasmus; Frangi, Alejandro F.; Larsen, Per; Perlyn, Chad A.; Morriss-Kay, Gillian M.; Kreiborg, Sven

    2007-03-01

    Crouzon syndrome is characterised by premature fusion of cranial sutures and synchondroses leading to craniofacial growth disturbances. The gene causing the syndrome was discovered approximately a decade ago and recently the first mouse model of the syndrome was generated. In this study, a set of Micro CT scans of the heads of wild-type (normal) mice and Crouzon mice were investigated. Statistical deformation models were built to assess the anatomical differences between the groups, as well as the within-group anatomical variation. Following the approach by Rueckert et al. we built an atlas using B-spline-based nonrigid registration and subsequently, the atlas was nonrigidly registered to the cases being modelled. The parameters of these registrations were then used as input to a PCA. Using different sets of registration parameters, different models were constructed to describe (i) the difference between the two groups in anatomical variation and (ii) the within-group variation. These models confirmed many known traits in the wild-type and Crouzon mouse craniofacial anatomy. However, they also showed some new traits.

  2. Solid Mesh Registration for Radiotherapy Treatment Planning

    DEFF Research Database (Denmark)

    Noe, Karsten Østergaard; Sørensen, Thomas Sangild

    2010-01-01

    We present an algorithm for solid organ registration of pre-segmented data represented as tetrahedral meshes. Registration of the organ surface is driven by force terms based on a distance field representation of the source and reference shapes. Registration of internal morphology is achieved usi...

  3. Clinical trial registration in oral health journals.

    Science.gov (United States)

    Smaïl-Faugeron, V; Fron-Chabouis, H; Durieux, P

    2015-03-01

    Prospective registration of randomized controlled trials (RCTs) represents the best solution to reporting bias. The extent to which oral health journals have endorsed and complied with RCT registration is unknown. We identified journals publishing RCTs in dentistry, oral surgery, and medicine in the Journal Citation Reports. We classified journals into 3 groups: journals requiring or recommending trial registration, journals referring indirectly to registration, and journals providing no reference to registration. For the 5 journals with the highest 2012 impact factors in each group, we assessed whether RCTs with results published in 2013 had been registered. Of 78 journals examined, 32 (41%) required or recommended trial registration, 19 (24%) referred indirectly to registration, and 27 (35%) provided no reference to registration. We identified 317 RCTs with results published in the 15 selected journals in 2013. Overall, 73 (23%) were registered in a trial registry. Among those, 91% were registered retrospectively and 32% did not report trial registration in the published article. The proportion of trials registered was not significantly associated with editorial policies: 29% with results in journals that required or recommended registration, 15% in those that referred indirectly to registration, and 21% in those providing no reference to registration (P = 0.05). Less than one-quarter of RCTs with results published in a sample of oral health journals were registered with a public registry. Improvements are needed with respect to how journals inform and require their authors to register their trials.

  4. 28 CFR 811.7 - Initial registration.

    Science.gov (United States)

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Initial registration. 811.7 Section 811.7... OFFENDER REGISTRATION § 811.7 Initial registration. (a) Duties of sex offender. (1) A sex offender must... incarceration or confinement, or entering the District of Columbia to live, reside, work, or attend school....

  5. 9 CFR 2.30 - Registration.

    Science.gov (United States)

    2010-01-01

    ... sign the registration form. (2) In any situation in which a school or department of a university or... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Registration. 2.30 Section 2.30... WELFARE REGULATIONS Research Facilities § 2.30 Registration. (a) Requirements and procedures. (1)...

  6. Toward adaptive radiotherapy for head and neck patients: Feasibility study on using CT-to-CBCT deformable registration for “dose of the day” calculations

    Energy Technology Data Exchange (ETDEWEB)

    Veiga, Catarina, E-mail: catarina.veiga.11@ucl.ac.uk; Lourenço, Ana; Ricketts, Kate; Annkah, James; Royle, Gary [Radiation Physics Group, Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT (United Kingdom); McClelland, Jamie; Modat, Marc; Ourselin, Sébastien [Centre for Medical Image Computing, Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT (United Kingdom); Moinuddin, Syed [Department of Radiotherapy, University College London Hospital, London NW1 2BU (United Kingdom); D’Souza, Derek [Department of Radiotherapy Physics, University College London Hospital, London NW1 2PG (United Kingdom)

    2014-03-15

    Purpose: The aim of this study was to evaluate the appropriateness of using computed tomography (CT) to cone-beam CT (CBCT) deformable image registration (DIR) for the application of calculating the “dose of the day” received by a head and neck patient. Methods: NiftyReg is an open-source registration package implemented in our institution. The affine registration uses a Block Matching-based approach, while the deformable registration is a GPU implementation of the popular B-spline Free Form Deformation algorithm. Two independent tests were performed to assess the suitability of our registrations methodology for “dose of the day” calculations in a deformed CT. A geometric evaluation was performed to assess the ability of the DIR method to map identical structures between the CT and CBCT datasets. Features delineated in the planning CT were warped and compared with features manually drawn on the CBCT. The authors computed the dice similarity coefficient (DSC), distance transformation, and centre of mass distance between features. A dosimetric evaluation was performed to evaluate the clinical significance of the registrations errors in the application proposed and to identify the limitations of the approximations used. Dose calculations for the same intensity-modulated radiation therapy plan on the deformed CT and replan CT were compared. Dose distributions were compared in terms of dose differences (DD), gamma analysis, target coverage, and dose volume histograms (DVHs). Doses calculated in a rigidly aligned CT and directly in an extended CBCT were also evaluated. Results: A mean value of 0.850 in DSC was achieved in overlap between manually delineated and warped features, with the distance between surfaces being less than 2 mm on over 90% of the pixels. Deformable registration was clearly superior to rigid registration in mapping identical structures between the two datasets. The dose recalculated in the deformed CT is a good match to the dose calculated on

  7. Toward adaptive radiotherapy for head and neck patients: Feasibility study on using CT-to-CBCT deformable registration for “dose of the day” calculations

    International Nuclear Information System (INIS)

    Purpose: The aim of this study was to evaluate the appropriateness of using computed tomography (CT) to cone-beam CT (CBCT) deformable image registration (DIR) for the application of calculating the “dose of the day” received by a head and neck patient. Methods: NiftyReg is an open-source registration package implemented in our institution. The affine registration uses a Block Matching-based approach, while the deformable registration is a GPU implementation of the popular B-spline Free Form Deformation algorithm. Two independent tests were performed to assess the suitability of our registrations methodology for “dose of the day” calculations in a deformed CT. A geometric evaluation was performed to assess the ability of the DIR method to map identical structures between the CT and CBCT datasets. Features delineated in the planning CT were warped and compared with features manually drawn on the CBCT. The authors computed the dice similarity coefficient (DSC), distance transformation, and centre of mass distance between features. A dosimetric evaluation was performed to evaluate the clinical significance of the registrations errors in the application proposed and to identify the limitations of the approximations used. Dose calculations for the same intensity-modulated radiation therapy plan on the deformed CT and replan CT were compared. Dose distributions were compared in terms of dose differences (DD), gamma analysis, target coverage, and dose volume histograms (DVHs). Doses calculated in a rigidly aligned CT and directly in an extended CBCT were also evaluated. Results: A mean value of 0.850 in DSC was achieved in overlap between manually delineated and warped features, with the distance between surfaces being less than 2 mm on over 90% of the pixels. Deformable registration was clearly superior to rigid registration in mapping identical structures between the two datasets. The dose recalculated in the deformed CT is a good match to the dose calculated on

  8. Image Registration Concept and Techniques: A Review

    Directory of Open Access Journals (Sweden)

    Sombir Singh Bisht

    2014-04-01

    Full Text Available In the past few years the global need for low computation, less time consuming, and good quality image mapping methods has caused an image registration technique alive in multiple application areas. Image registration is the method of superimposition the pixels or control points from one image over another image namely the target image and reference image respectively. The concentration is on various methods of mapping parameters. Input images are reference image and the sensed image. Basically image registration is of two types Area based and Feature based. Area based works on the intensity of image and feature based is based on feature points or objects of image. Also the simple and efficient registration techniques are very essential in many application areas. This paper presents a review on image registration techniques as well as the hybrid registration approach. Many authors have also reported the modified registration techniques, each technique is reviewed according to its merits and drawbacks.

  9. Ensemble learning incorporating uncertain registration.

    Science.gov (United States)

    Simpson, Ivor J A; Woolrich, Mark W; Andersson, Jesper L R; Groves, Adrian R; Schnabel, Julia A

    2013-04-01

    This paper proposes a novel approach for improving the accuracy of statistical prediction methods in spatially normalized analysis. This is achieved by incorporating registration uncertainty into an ensemble learning scheme. A probabilistic registration method is used to estimate a distribution of probable mappings between subject and atlas space. This allows the estimation of the distribution of spatially normalized feature data, e.g., grey matter probability maps. From this distribution, samples are drawn for use as training examples. This allows the creation of multiple predictors, which are subsequently combined using an ensemble learning approach. Furthermore, extra testing samples can be generated to measure the uncertainty of prediction. This is applied to separating subjects with Alzheimer's disease from normal controls using a linear support vector machine on a region of interest in magnetic resonance images of the brain. We show that our proposed method leads to an improvement in discrimination using voxel-based morphometry and deformation tensor-based morphometry over bootstrap aggregating, a common ensemble learning framework. The proposed approach also generates more reasonable soft-classification predictions than bootstrap aggregating. We expect that this approach could be applied to other statistical prediction tasks where registration is important. PMID:23288332

  10. Calculation of the temperature of asphalt concrete at making the joints of multilane road pavement of non-rigid type

    Directory of Open Access Journals (Sweden)

    Giyasov Botir Iminzhonovich

    2015-03-01

    Full Text Available The construction quality of road surface of non-rigid type essentially depend on providing the temperature regimes in the process of laying and packing of hot asphalt concrete mixtures. In order to provide the required characteristics of asphalt concrete due to the surface width it is necessary to provide the temperature regimes of hot asphalt concrete mixture in the zones of lane connection. The hot mixture is promptly cooling right after laying within several minutes, which results, according to the construction technology and the specific conditions of work production, in temperature abuse of the mixture at joints of the lanes at packing. The authors present the analysis of the technology of arranging multilane road surface by one paver with the possibility of heating the surface lane edge with the temperature of the adjacent lane. The results of the studies of the production conditions effect on the temperature of edge heating of the previously laid lanes, and the time required to achieve the maximum heating temperature depending on the relative thickness of coating layers.

  11. Diffusion tensor image registration using polynomial expansion

    International Nuclear Information System (INIS)

    In this paper, we present a deformable registration framework for the diffusion tensor image (DTI) using polynomial expansion. The use of polynomial expansion in image registration has previously been shown to be beneficial due to fast convergence and high accuracy. However, earlier work was developed only for 3D scalar medical image registration. In this work, it is shown how polynomial expansion can be applied to DTI registration. A new measurement is proposed for DTI registration evaluation, which seems to be robust and sensitive in evaluating the result of DTI registration. We present the algorithms for DTI registration using polynomial expansion by the fractional anisotropy image, and an explicit tensor reorientation strategy is inherent to the registration process. Analytic transforms with high accuracy are derived from polynomial expansion and used for transforming the tensor's orientation. Three measurements for DTI registration evaluation are presented and compared in experimental results. The experiments for algorithm validation are designed from simple affine deformation to nonlinear deformation cases, and the algorithms using polynomial expansion give a good performance in both cases. Inter-subject DTI registration results are presented showing the utility of the proposed method. (paper)

  12. [Progress of research in retinal image registration].

    Science.gov (United States)

    Yu, Lun; Wei, Lifang; Pan, Lin

    2011-10-01

    The retinal image registration has important applications in the processes of auxiliary diagnosis and treatment for a variety of diseases. The retinal image registration can be used to measure the disease process and the therapeutic effect. A variety of retinal image registration techniques have been studied extensively in recent years. However, there are still many problems existing and there are numerous research possibilities. Based on extensive investigation of existing literatures, the present paper analyzes the feature of retinal image and current challenges of retinal image registration, and reviews the transformation models of the retinal image registration technology and the main research algorithms in current retinal image registration, and analyzes the advantages and disadvantages of various types of algorithms. Some research challenges and future developing trends are also discussed.

  13. Registration probability of alphas in cellulose nitrate

    International Nuclear Information System (INIS)

    Registration 'thresholds' of alpha particles in cellulose nitrate plastic present a statistical behaviour. The effect depends on etching conditions. It is particularly large in strong etching conditions, in which registration is transposed to high energies: up to 7.7 MeV for the conditions and energies studied. 'Registration probability' expresses more adequately the effect of registration constraints. The study of registration probability indicates that the 'target theory' can describe the effect. The parameters of target theory, m (number of targets) and D0 (the equivalent of biological dose D37) were found to be: m = 5 and D0 = 3 x 107 erg cm-3. Dose distribution around the trajectory of alphas of various energies is estimated. It is also deduced that track development takes place when the required dose for registration is deposited at a distance r >= 20 A from particle trajectory. (author)

  14. Robust Brain Registration using Adaptive Probabilistic Atlas

    OpenAIRE

    Ide, Jaime; Chen, Rong; Shen, Dinggang; Edward H Herskovits

    2008-01-01

    Elastic image registration is widely used to adapt brain images to a common template space, and, in complementary fashion, to adapt an anatomical template to a subject's anatomy. Although HAMMER is a very accurate image-registration algorithm, it requires a 3-class segmentation step prior to registration, and its performance is affected by segmentation quality. We here propose a new framework to improve this algorithm's robustness to poor initial segmentation. Our new framework is based on Ad...

  15. Registration Day-Camp 2016

    CERN Multimedia

    Nursery School

    2016-01-01

    Reminder Registration for the CERN Staff Association Day-camp are open for children from 4 to 6 years old More information on the website: http://nurseryschool.web.cern.ch/. The day-camp is open to all children. An inscription per week is proposed, cost 480.-CHF/week, lunch included The camp will be open weeks 27, 28, 29 and 30, from 8:30 am to 5:30 pm. For further questions, thanks you for contacting us by email at Summer.Camp@cern.ch.

  16. 75 FR 37790 - Lauryl Sulfate Salts; Antimicrobial Registration Review Final Work Plan and Proposed Registration...

    Science.gov (United States)

    2010-06-30

    ... AGENCY Lauryl Sulfate Salts; Antimicrobial Registration Review Final Work Plan and Proposed Registration.... SUMMARY: This notice announces the availability of EPA's final work plan and proposed registration review... with the posting of a summary document, containing a preliminary work plan, for public comment....

  17. Higher-order momentum distributions and locally affine LDDMM registration

    DEFF Research Database (Denmark)

    Sommer, Stefan Horst; Nielsen, Mads; Darkner, Sune;

    2013-01-01

    description of affine transformations and subsequent compact description of non-translational movement in a globally nonrigid deformation. The resulting representation contains directly interpretable information from both mathematical and modeling perspectives. We develop the mathematical construction...... higher-order momenta lead to natural modeling of articulated movement, and the method promises to be useful for quantifying ventricle expansion and progressing atrophy during Alzheimer's disease....

  18. 3D Visual Data-Driven Spatiotemporal Deformations for Non-Rigid Object Grasping Using Robot Hands.

    Science.gov (United States)

    Mateo, Carlos M; Gil, Pablo; Torres, Fernando

    2016-05-05

    Sensing techniques are important for solving problems of uncertainty inherent to intelligent grasping tasks. The main goal here is to present a visual sensing system based on range imaging technology for robot manipulation of non-rigid objects. Our proposal provides a suitable visual perception system of complex grasping tasks to support a robot controller when other sensor systems, such as tactile and force, are not able to obtain useful data relevant to the grasping manipulation task. In particular, a new visual approach based on RGBD data was implemented to help a robot controller carry out intelligent manipulation tasks with flexible objects. The proposed method supervises the interaction between the grasped object and the robot hand in order to avoid poor contact between the fingertips and an object when there is neither force nor pressure data. This new approach is also used to measure changes to the shape of an object's surfaces and so allows us to find deformations caused by inappropriate pressure being applied by the hand's fingers. Test was carried out for grasping tasks involving several flexible household objects with a multi-fingered robot hand working in real time. Our approach generates pulses from the deformation detection method and sends an event message to the robot controller when surface deformation is detected. In comparison with other methods, the obtained results reveal that our visual pipeline does not use deformations models of objects and materials, as well as the approach works well both planar and 3D household objects in real time. In addition, our method does not depend on the pose of the robot hand because the location of the reference system is computed from a recognition process of a pattern located place at the robot forearm. The presented experiments demonstrate that the proposed method accomplishes a good monitoring of grasping task with several objects and different grasping configurations in indoor environments.

  19. 3D Visual Data-Driven Spatiotemporal Deformations for Non-Rigid Object Grasping Using Robot Hands

    Science.gov (United States)

    Mateo, Carlos M.; Gil, Pablo; Torres, Fernando

    2016-01-01

    Sensing techniques are important for solving problems of uncertainty inherent to intelligent grasping tasks. The main goal here is to present a visual sensing system based on range imaging technology for robot manipulation of non-rigid objects. Our proposal provides a suitable visual perception system of complex grasping tasks to support a robot controller when other sensor systems, such as tactile and force, are not able to obtain useful data relevant to the grasping manipulation task. In particular, a new visual approach based on RGBD data was implemented to help a robot controller carry out intelligent manipulation tasks with flexible objects. The proposed method supervises the interaction between the grasped object and the robot hand in order to avoid poor contact between the fingertips and an object when there is neither force nor pressure data. This new approach is also used to measure changes to the shape of an object’s surfaces and so allows us to find deformations caused by inappropriate pressure being applied by the hand’s fingers. Test was carried out for grasping tasks involving several flexible household objects with a multi-fingered robot hand working in real time. Our approach generates pulses from the deformation detection method and sends an event message to the robot controller when surface deformation is detected. In comparison with other methods, the obtained results reveal that our visual pipeline does not use deformations models of objects and materials, as well as the approach works well both planar and 3D household objects in real time. In addition, our method does not depend on the pose of the robot hand because the location of the reference system is computed from a recognition process of a pattern located place at the robot forearm. The presented experiments demonstrate that the proposed method accomplishes a good monitoring of grasping task with several objects and different grasping configurations in indoor environments. PMID

  20. 40 CFR 68.160 - Registration.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 15 2010-07-01 2010-07-01 false Registration. 68.160 Section 68.160 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CHEMICAL ACCIDENT PREVENTION PROVISIONS Risk Management Plan § 68.160 Registration. (a) The owner or operator...

  1. Registrering af praehabilitering inden planlagt operation

    DEFF Research Database (Denmark)

    Tønnesen, Hanne; Duus, Benn Rønnow

    2008-01-01

    for registration of prehabilitation prior to surgery. Using one specific code for prehabilitation at the surgical department and another for prehabilitation at other departments will enable correct registration. Thereby, it is possible to differentiate between ordinary waiting time before surgery and time...

  2. 19 CFR 360.102 - Online registration.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 3 2010-04-01 2010-04-01 false Online registration. 360.102 Section 360.102... ANALYSIS SYSTEM § 360.102 Online registration. (a) In general. (1) Any importer, importing company, customs.... boxes will not be accepted. A user identification number will be issued within two business...

  3. Image Registration for Stability Testing of MEMS

    Science.gov (United States)

    Memarsadeghi, Nargess; LeMoigne, Jacqueline; Blake, Peter N.; Morey, Peter A.; Landsman, Wayne B.; Chambers, Victor J.; Moseley, Samuel H.

    2011-01-01

    Image registration, or alignment of two or more images covering the same scenes or objects, is of great interest in many disciplines such as remote sensing, medical imaging. astronomy, and computer vision. In this paper, we introduce a new application of image registration algorithms. We demonstrate how through a wavelet based image registration algorithm, engineers can evaluate stability of Micro-Electro-Mechanical Systems (MEMS). In particular, we applied image registration algorithms to assess alignment stability of the MicroShutters Subsystem (MSS) of the Near Infrared Spectrograph (NIRSpec) instrument of the James Webb Space Telescope (JWST). This work introduces a new methodology for evaluating stability of MEMS devices to engineers as well as a new application of image registration algorithms to computer scientists.

  4. Effects of land registration on validity of juridical acts (Emphasis on Functions of land registration System

    Directory of Open Access Journals (Sweden)

    Nasrin tabatabai hesari

    2015-12-01

    Full Text Available Guaranty of security of juridical act about lands is a more important difficulties in every country. Disregarding the independence of land registration system from the system of civil law and disregarding bases and functions of land registration system has resulted in making mistakes by judicial doctrine and precedent in order to propose proper suggestions for solving the problems related to land registration system and to sanction for juridical acts about lands. Whiles presentation every solution in this scope must be proper regarding to protective bases of owner and third parties and two functional characters of the land registration system including “informing” and “protective” features. land registration systems can be divided in constitutive registration system and confirmative one. This classification means land registration in any case, has a very effective role in credit of judicial act about of land although the degree of this effect is different depending on the system.

  5. A gaussian mixture + demons deformable registration method for cone-beam CT-guided robotic transoral base-of-tongue surgery

    Science.gov (United States)

    Reaungamornrat, S.; Liu, W. P.; Schafer, S.; Otake, Y.; Nithiananthan, S.; Uneri, A.; Richmon, J.; Sorger, J.; Siewerdsen, J. H.; Taylor, R. H.

    2013-03-01

    demonstrated improved registration, achieving mean TRE of 3.0 mm following the GM rigid, 1.9 mm following GM nonrigid, and 1.5 mm at the output of the registration process. Analysis of surface distance demonstrated a corresponding improvement of 2.2, 0.4, and 0.3 mm, respectively. The evaluation of registration error revealed the accurate alignment in the region of interest for base-of-tongue robotic surgery owing to point-set selection in the GM steps and refinement in the deep aspect of the tongue in the Demons step. Conclusions: A promising framework has been developed for CBCT-guided TORS in which intraoperative CBCT provides a basis for registration of preoperative images to the highly deformed intraoperative setup. The registration framework is invariant to imaging modality (accommodating preoperative CT or MR) and is robust against CBCT intensity variations and artifact, provided corresponding segmentation of the volume of interest. The approach could facilitate overlay of preoperative planning data directly in stereo-endoscopic video in support of CBCT-guided TORS.

  6. Registration Day-Camp 2016

    CERN Multimedia

    Nursery School

    2016-01-01

    Registration for the CERN SA Day-camp are open for children from 4 to 6 years old From March 14 to 25 for children already enrolled in CERN SA EVE and School From April 4 to 15 for the children of CERN members of the personnel (MP) From April 18 for other children More information on the website: http://nurseryschool.web.cern.ch/. The day-camp is open to all children. An inscription per week is proposed, cost 480.-CHF/week, lunch included The camp will be open weeks 27, 28, 29 and 30, from 8:30 am to 5:30 pm. For further questions, thanks you for contacting us by email at Summer.Camp@cern.ch.

  7. Study on 3D Distribution of Pulmonary Ventilation Based on 4D-CT and Deformation Image Registration%基于4D-CT和变形图像配准获取肺通气功能的三维分布

    Institute of Scientific and Technical Information of China (English)

    张书旭; 余辉; 林生趣; 张国前; 王锐濠; 齐斌

    2013-01-01

    Objective To obtain 3D distribution images of pulmonary ventilation based on 4D-CT and deformation image registration (DIR). Methods The 4D-CT data sets were acquired with patients in free-breathing. 3D displacement vector ifeld (DVF) of two different phase 4D-CT image pairs was calculated out by using 3D B-spline DIR algorithms, which was converted to Jacobian determinant. Then, the axial section of grayscale ventilation was obtained by quantitative analysis of the determinant. The pseudo-color was put on the axial grayscale ventilation before fused with the reference CT images. And based on the axial ventilation, the coronal and sagittal sections of ventilations can be reconstructed. Thus, 3D visualization ventilations have been implemented. The contours of the ventilation regions with different Jacobian values were delineated and the volumes of them were calculated. Results Based on 4D-CT images of patients in free-breathing and multi-resolution 3D B-spline DIR, the 3D visualization ventilation can be easily obtained and quantiifed. The volume change of lung is signiifcantly related with the volume of different ventilation regions at level 0.05 (bilateral). Conclusion It is simple, convenient and feasible to obtain the 3D distribution of pulmonary ventilation based on the 4D-CT images and 3D B-spline DIR.%目的:获取基于4D-CT和变形图像配准方法,建立肺通气功能的三维分布图像。方法在患者自由呼吸状态下进行肺部4D-CT图像采集和重建;用B样条三维变形配准算法,对4D-CT中不同相位的两个CT图像系列进行配准,获得三维变形场文件,再将该文件转换为雅可比行列式矩阵,根据其物理含义进行量化分析,得到任意横断面的通气分布图像。将此图像伪彩化后与CT图像融合,再进行任意冠状面、矢状面重建,从而得到直观的横断面、冠状面、矢状面三维方向的通气功能分布。将自动勾画并计算出的不同功能肺

  8. Development and evaluation of an articulated registration algorithm for human skeleton registration

    International Nuclear Information System (INIS)

    Accurate registration over multiple scans is necessary to assess treatment response of bone diseases (e.g. metastatic bone lesions). This study aimed to develop and evaluate an articulated registration algorithm for the whole-body skeleton registration in human patients. In articulated registration, whole-body skeletons are registered by auto-segmenting into individual bones using atlas-based segmentation, and then rigidly aligning them. Sixteen patients (weight = 80–117 kg, height = 168–191 cm) with advanced prostate cancer underwent the pre- and mid-treatment PET/CT scans over a course of cancer therapy. Skeletons were extracted from the CT images by thresholding (HU>150). Skeletons were registered using the articulated, rigid, and deformable registration algorithms to account for position and postural variability between scans. The inter-observers agreement in the atlas creation, the agreement between the manually and atlas-based segmented bones, and the registration performances of all three registration algorithms were all assessed using the Dice similarity index—DSIobserved, DSIatlas, and DSIregister. Hausdorff distance (dHausdorff) of the registered skeletons was also used for registration evaluation. Nearly negligible inter-observers variability was found in the bone atlases creation as the DSIobserver was 96 ± 2%. Atlas-based and manual segmented bones were in excellent agreement with DSIatlas of 90 ± 3%. Articulated (DSIregsiter = 75 ± 2%, dHausdorff = 0.37 ± 0.08 cm) and deformable registration algorithms (DSIregister = 77 ± 3%, dHausdorff = 0.34 ± 0.08 cm) considerably outperformed the rigid registration algorithm (DSIregsiter = 59 ± 9%, dHausdorff = 0.69 ± 0.20 cm) in the skeleton registration as the rigid registration algorithm failed to capture the skeleton flexibility in the joints. Despite superior skeleton registration performance, deformable registration algorithm failed to preserve the local rigidity of bones as over

  9. A Multistage Approach for Image Registration.

    Science.gov (United States)

    Bowen, Francis; Hu, Jianghai; Du, Eliza Yingzi

    2016-09-01

    Successful image registration is an important step for object recognition, target detection, remote sensing, multimodal content fusion, scene blending, and disaster assessment and management. The geometric and photometric variations between images adversely affect the ability for an algorithm to estimate the transformation parameters that relate the two images. Local deformations, lighting conditions, object obstructions, and perspective differences all contribute to the challenges faced by traditional registration techniques. In this paper, a novel multistage registration approach is proposed that is resilient to view point differences, image content variations, and lighting conditions. Robust registration is realized through the utilization of a novel region descriptor which couples with the spatial and texture characteristics of invariant feature points. The proposed region descriptor is exploited in a multistage approach. A multistage process allows the utilization of the graph-based descriptor in many scenarios thus allowing the algorithm to be applied to a broader set of images. Each successive stage of the registration technique is evaluated through an effective similarity metric which determines subsequent action. The registration of aerial and street view images from pre- and post-disaster provide strong evidence that the proposed method estimates more accurate global transformation parameters than traditional feature-based methods. Experimental results show the robustness and accuracy of the proposed multistage image registration methodology. PMID:26292357

  10. Masked object registration in the Fourier domain.

    Science.gov (United States)

    Padfield, Dirk

    2012-05-01

    Registration is one of the most common tasks of image analysis and computer vision applications. The requirements of most registration algorithms include large capture range and fast computation so that the algorithms are robust to different scenarios and can be computed in a reasonable amount of time. For these purposes, registration in the Fourier domain using normalized cross-correlation is well suited and has been extensively studied in the literature. Another common requirement is masking, which is necessary for applications where certain regions of the image that would adversely affect the registration result should be ignored. To address these requirements, we have derived a mathematical model that describes an exact form for embedding the masking step fully into the Fourier domain so that all steps of translation registration can be computed efficiently using Fast Fourier Transforms. We provide algorithms and implementation details that demonstrate the correctness of our derivations. We also demonstrate how this masked FFT registration approach can be applied to improve the Fourier-Mellin algorithm that calculates translation, rotation, and scale in the Fourier domain. We demonstrate the computational efficiency, advantages, and correctness of our algorithm on a number of images from real-world applications. Our framework enables fast, global, parameter-free registration of images with masked regions.

  11. Cellular recurrent deep network for image registration

    Science.gov (United States)

    Alam, M.; Vidyaratne, L.; Iftekharuddin, Khan M.

    2015-09-01

    Image registration using Artificial Neural Network (ANN) remains a challenging learning task. Registration can be posed as a two-step problem: parameter estimation and actual alignment/transformation using the estimated parameters. To date ANN based image registration techniques only perform the parameter estimation, while affine equations are used to perform the actual transformation. In this paper, we propose a novel deep ANN based image rigid registration that combines parameter estimation and transformation as a simultaneous learning task. Our previous work shows that a complex universal approximator known as Cellular Simultaneous Recurrent Network (CSRN) can successfully approximate affine transformations with known transformation parameters. This study introduces a deep ANN that combines a feed forward network with a CSRN to perform full rigid registration. Layer wise training is used to pre-train feed forward network for parameter estimation and followed by a CSRN for image transformation respectively. The deep network is then fine-tuned to perform the final registration task. Our result shows that the proposed deep ANN architecture achieves comparable registration accuracy to that of image affine transformation using CSRN with known parameters. We also demonstrate the efficacy of our novel deep architecture by a performance comparison with a deep clustered MLP.

  12. Tensor scale-based image registration

    Science.gov (United States)

    Saha, Punam K.; Zhang, Hui; Udupa, Jayaram K.; Gee, James C.

    2003-05-01

    Tangible solutions to image registration are paramount in longitudinal as well as multi-modal medical imaging studies. In this paper, we introduce tensor scale - a recently developed local morphometric parameter - in rigid image registration. A tensor scale-based registration method incorporates local structure size, orientation and anisotropy into the matching criterion, and therefore, allows efficient multi-modal image registration and holds potential to overcome the effects of intensity inhomogeneity in MRI. Two classes of two-dimensional image registration methods are proposed - (1) that computes angular shift between two images by correlating their tensor scale orientation histogram, and (2) that registers two images by maximizing the similarity of tensor scale features. Results of applications of the proposed methods on proton density and T2-weighted MR brain images of (1) the same slice of the same subject, and (2) different slices of the same subject are presented. The basic superiority of tensor scale-based registration over intensity-based registration is that it may allow the use of local Gestalts formed by the intensity patterns over the image instead of simply considering intensities as isolated events at the pixel level. This would be helpful in dealing with the effects of intensity inhomogeneity and noise in MRI.

  13. Registration accuracy for MR images of the prostate using a subvolume based registration protocol

    Directory of Open Access Journals (Sweden)

    Söderström Karin

    2011-06-01

    Full Text Available Abstract Background In recent years, there has been a considerable research effort concerning the integration of magnetic resonance imaging (MRI into the external radiotherapy workflow motivated by the superior soft tissue contrast as compared to computed tomography. Image registration is a necessary step in many applications, e.g. in patient positioning and therapy response assessment with repeated imaging. In this study, we investigate the dependence between the registration accuracy and the size of the registration volume for a subvolume based rigid registration protocol for MR images of the prostate. Methods Ten patients were imaged four times each over the course of radiotherapy treatment using a T2 weighted sequence. The images were registered to each other using a mean square distance metric and a step gradient optimizer for registration volumes of different sizes. The precision of the registrations was evaluated using the center of mass distance between the manually defined prostates in the registered images. The optimal size of the registration volume was determined by minimizing the standard deviation of these distances. Results We found that prostate position was most uncertain in the anterior-posterior (AP direction using traditional full volume registration. The improvement in standard deviation of the mean center of mass distance between the prostate volumes using a registration volume optimized to the prostate was 3.9 mm (p Conclusions Repeated MR imaging of the prostate for therapy set-up or therapy assessment will both require high precision tissue registration. With a subvolume based registration the prostate registration uncertainty can be reduced down to the order of 1 mm (1 SD compared to several millimeters for registration based on the whole pelvis.

  14. Deformable registration for integration of MRI/MRSI information in TRUS-guided prostate biopsy

    Science.gov (United States)

    Shao, Wei; Wu, Ruoyun; Thng, Choon Hua; Ling, Keck Voon; Ho, Henry Sun Sien; Cheng, Christopher Wai Sam; Ng, Wan Sing

    2005-04-01

    Prostate cancer has been ranked as the second leading cause of cancer death in men. The existence of cancer in prostate is usually examined by a biopsy procedure under the transrectal ultrasound (TRUS) guidance. Development of a prostate biopsy robotics can alleviate urologists' labor and guarantee accuracy. However, it is usually impossible to identify cancer region in the noisy ultrasound images, thus leading to a random biopsy protocol for prostate. It is being recognized that Magnetic Resonance Imaging (MRI) and Magnetic Resonance Spectroscopy Imaging (MRSI) techniques are potential to diagnose cancer distribution in prostate. So navigating the biopsy needle towards those cancer-suspected sites could improve the cancer detection rate and reduce the possibility of false negative diagnosis results. As the prostate usually deforms under the different rectal filling of probes and change of patient postures, a deformable registration scheme is implemented for the integration of the pre-operative MRI/MRSI information with the intra-operative TRUS images. A framework including a global rigid alignment and a sequent non-rigid transformation was described in this paper to match the cross-modal prostate surfaces and thereafter their volumes. For validation, an elastic prostate phantom that simulated the human condition was built up, with fiducial markers implanted inside the phantom prostate as the "ground truth". It shows that our method can achieve at least 30% improvement in accuracy compared with an affine transformation. Preliminary study was also conducted on patient data but with visual assessments presented only due to the current lack of "ground truth".

  15. Fast musculoskeletal registration based on shape matching.

    Science.gov (United States)

    Gilles, Benjamin; Pai, Dinesh K

    2008-01-01

    This paper presents a new method for computing elastic and plastic deformations in the context of discrete deformable model-based registration. Internal forces are estimated by averaging local transforms between reference and current particle positions. Our technique can accommodate large non-linear deformations, and is unconditionally stable. Moreover, it is simple to implement and versatile. We show how to tune model stiffness and computational cost, which is important for efficient registration, and demonstrate our technique in the complex problem of inter-patient musculoskeletal registration. PMID:18982681

  16. Mean Shift Registration Algorithm for Dissimilar Sensors

    Institute of Scientific and Technical Information of China (English)

    QI Yong-qing; JING Zhong-liang; HU Shi-qiang; ZHAO Hai-tao

    2009-01-01

    The mean shift registration (MSR) algorithm is proposed to accurately estimate the biases for multiple dissimilar sensors. The new algorithm is a batch optimization procedure. The maximum likelihood estimator is used to estimate the target states, and then the mean shift algorithm is implemented to estimate the sensor biases. Monte Carlo simulations show that the MSR algorithm has significant improvement in performance with reducing the standard deviation and mean of sensor biased estimation error compared with the maximum likelihood registration algorithm. The quantitative analysis and the qualitative analysis show that the MSR algorithm has less computation than the maximum likelihood registration method.

  17. Adaptive Hierarchical B-spline Surface Representation of Large-Scale Scattered Data

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The representation of large scale scattered data is a difficult problem, especially when various features of the representation, such as C2-continuity, are required. This paper describes a fast algorithm for large scale scattered data approximation and interpolation. The interpolation algorithm uses a coarse-to-fine hierarchical control lattice to fit the scattered data. The refinement process is only used in the regions where the error between the scattered data and the result in a surface is greater than a specified tolerance. A method to ensure C2-continuity is introduced to calculate the control lattice under constrained conditions. Experimental results show that this method can quickly represent large scale scattered data set.

  18. A sparse collocation method for solving time-dependent HJB equations using multivariate B-splines

    NARCIS (Netherlands)

    Govindarajan, N.; De Visser, C.C.; Krishnakumar, K.

    2014-01-01

    This paper presents a sparse collocation method for solving the time-dependent Hamilton–Jacobi–Bellman (HJB) equation associated with the continuous-time optimal control problem on a fixed, finite timehorizon with integral cost functional. Through casting the problem in a recursive framework using t

  19. C-B样条基是B基%C-B-spline basis is B-basis

    Institute of Scientific and Technical Information of China (English)

    闵春燕; 汪国昭

    2004-01-01

    证明了空间Гn+1=span{1,t,…,tn-2,sint,cos t}n≥2中的定义域两端是n重节点的非均匀C-B样条基是B基,是适合CAGD多种需要的具有良好性质的基.B基具有de Casteljau类型算法,同时也提供求值和细分.这表明非均匀C-B样条基可作为CAGD新的造型工具.

  20. B -spline R -matrix-with-pseudostates calculations for electron collisions with aluminum

    Science.gov (United States)

    Gedeon, Viktor; Gedeon, Sergej; Lazur, Vladimir; Nagy, Elizabeth; Zatsarinny, Oleg; Bartschat, Klaus

    2015-11-01

    A systematic study of angle-integrated cross sections for electron scattering from neutral aluminum is presented. The calculations cover elastic scattering, excitation of the 14 states (3 s2n p ) P2o (n =3 ,4 ,5 ,6 ) , (3 s2n s ) 2S (n =4 ,5 ,6 ) , (3 s2n d ) 2D (n =3 ,4 ) , (3 s 3 p2)P,24,2D,2S , and (3 s24 f ) F2o , as well as electron impact ionization. The sensitivity of the results to changes in the theoretical model is checked by comparing predictions from a variety of approximations, including a large-scale model with over 500 continuum pseudostates. The current results are believed to be accurate at the few-percent level and should represent a sufficiently extensive set of electron collision data for most modeling applications involving neutral aluminum.

  1. Projection of curves on B-spline surfaces using quadratic reparameterization

    KAUST Repository

    Yang, Yijun

    2010-09-01

    Curves on surfaces play an important role in computer aided geometric design. In this paper, we present a hyperbola approximation method based on the quadratic reparameterization of Bézier surfaces, which generates reasonable low degree curves lying completely on the surfaces by using iso-parameter curves of the reparameterized surfaces. The Hausdorff distance between the projected curve and the original curve is controlled under the user-specified distance tolerance. The projected curve is T-G 1 continuous, where T is the user-specified angle tolerance. Examples are given to show the performance of our algorithm. © 2010 Elsevier Inc. All rights reserved.

  2. B-splines on 3-D tetrahedron partition in four-directional mesh

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    It is more difficult to construct 3-D splines than in 2-D case. Some results in the three directional meshes of bivariate case have been e xtended to 3-D case and corresponding tetrahedron partition has been constructed. The support of related Bsplines and their recurrent formulas on integration and differentiationdifference are obtained. The results of this paper can be extended into higher dimension spaces, and can be also used in wavelet analysis, because of the relationship between spline and wavelets.

  3. Numerical solution of functional integral equations by using B-splines

    Directory of Open Access Journals (Sweden)

    Reza Firouzdor

    2014-05-01

    Full Text Available This paper describes an approximating solution, based on Lagrange interpolation and spline functions, to treat functional integral equations of Fredholm type and Volterra type. This method can be extended to functional dierential and integro-dierential equations. For showing eciency of the method we give some numerical examples.

  4. Inference in dynamic systems using B-splines and quasilinearized ODE penalties.

    Science.gov (United States)

    Frasso, Gianluca; Jaeger, Jonathan; Lambert, Philippe

    2016-05-01

    Nonlinear (systems of) ordinary differential equations (ODEs) are common tools in the analysis of complex one-dimensional dynamic systems. We propose a smoothing approach regularized by a quasilinearized ODE-based penalty. Within the quasilinearized spline-based framework, the estimation reduces to a conditionally linear problem for the optimization of the spline coefficients. Furthermore, standard ODE compliance parameter(s) selection criteria are applicable. We evaluate the performances of the proposed strategy through simulated and real data examples. Simulation studies suggest that the proposed procedure ensures more accurate estimates than standard nonlinear least squares approaches when the state (initial and/or boundary) conditions are not known. PMID:26602190

  5. 15 CFR 295.24 - Registration.

    Science.gov (United States)

    2010-01-01

    ... Assistance to United States Industry-Led Joint Research and Development Ventures § 295.24 Registration. Joint ventures selected for funding under the Program must notify the Department of Justice and the Federal...

  6. 76 FR 10026 - Pesticide Products; Registration Applications

    Science.gov (United States)

    2011-02-23

    ... AGENCY Pesticide Products; Registration Applications AGENCY: Environmental Protection Agency (EPA). ACTION: Notice. SUMMARY: This notice announces receipt of applications to register new uses for pesticide... the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), as amended. EPA is publishing...

  7. Progressive refinement for robust image registration

    Institute of Scientific and Technical Information of China (English)

    Li Song; Yuanhua Zhou; Jun Zhou

    2005-01-01

    @@ A new image registration algorithm with robust cost function and progressive refinement estimation is developed on the basis of direct method (DM). The robustness lies in M-estimation to avert larger local noise and outliers.

  8. 76 FR 38160 - Pesticide Products; Registration Applications

    Science.gov (United States)

    2011-06-29

    ... AGENCY Pesticide Products; Registration Applications AGENCY: Environmental Protection Agency (EPA). ACTION: Notice. SUMMARY: EPA has received applications to register pesticide products containing an active ingredient not included in any previously registered pesticide products. Pursuant to...

  9. 75 FR 71695 - Pesticide Products; Registration Applications

    Science.gov (United States)

    2010-11-24

    ... AGENCY Pesticide Products; Registration Applications AGENCY: Environmental Protection Agency ACTION: Notice. SUMMARY: EPA has received applications to register new uses for pesticide products containing... Pesticide Programs (OPP) Regulatory Public Docket (7502P), Environmental Protection Agency,...

  10. 75 FR 24694 - Pesticide Products; Registration Applications

    Science.gov (United States)

    2010-05-05

    ... AGENCY Pesticide Products; Registration Applications AGENCY: Environmental Protection Agency (EPA). ACTION: Notice. SUMMARY: EPA has received applications to register pesticide products containing an active ingredient not included in any previously registered pesticide product. Pursuant to the...

  11. 47 CFR 1.8001 - FCC Registration Number (FRN).

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false FCC Registration Number (FRN). 1.8001 Section 1.8001 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL PRACTICE AND PROCEDURE FCC Registration Number § 1.8001 FCC Registration Number (FRN). (a) The FCC Registration Number (FRN) is a...

  12. Diffusion MRI Registration Using Orientation Distribution Functions

    OpenAIRE

    Geng, Xiujuan; Ross, Thomas J.; Zhan, Wang; Gu, Hong; Chao, Yi-Ping; Lin, Ching-Po; Christensen, Gary E.; Schuff, Norbert; Yang, Yihong

    2009-01-01

    We propose a linear-elastic registration method to register diffusion-weighted MRI (DW-MRI) data sets by mapping their diffusion orientation distribution functions (ODFs). The ODFs were reconstructed using a q-ball imaging (QBI) technique to resolve intravoxel fiber crossing. The registration method is based on mapping the ODF maps represented by spherical harmonics which yield analytic solutions and reduce the computational complexity. ODF reorientation is required to maintain the consistenc...

  13. A networked registration scheme for enhancing trust

    OpenAIRE

    Pickering, J Adrian; Gutteridge, Christopher

    2009-01-01

    Society has widely adopted use of electronic data without sufficient attention to the problems of non-repudiation (NR). A universal, transparent scheme is needed to replace the traditional paper-based model that people are familiar with. A registration scheme is proposed that uses a network of registration servers run in a way that is robust to legal and technical challenge. Any user can register potential electronic evidence with one or more of these servers. This enables a user to later ass...

  14. Central research registration at Technical University of Denmark (DTU)

    DEFF Research Database (Denmark)

    Sand, Ane Ahrenkiel

    Some five years ago, DTU switched from decentralized research registration, where researchers entered their publications into the DTU research repository themselves to centralized research registration, whereby library staff upload academic publications to the repository on behalf...... of the researchers. The implementation of the centralization process was accompanied by, and depended on, the establishment of a research registration team at the DTU Library. This session shares DTU’s five years of experience with centralized research registration, including: the implementation process, the setting...... up the registration team, the configuration of the repository platform (Pure), the registration workflow and last but not least the results since DTU switched to centralized research registration....

  15. Central Research Registration at Technical University of Denmark (DTU)

    DEFF Research Database (Denmark)

    Sand, Ane Ahrenkiel

    Some five years ago, DTU switched from decentralized research registration, where researchers entered their publications into the DTU research repository themselves to centralized research registration, whereby library staff upload academic publications to the repository on behalf...... of the researchers. The implementation of the centralization process was accompanied by, and depended on, the establishment of a research registration team at the DTU Library. This session shares DTU’s five years of experience with centralized research registration, including: the implementation process, the setting...... up the registration team, the configuration of the repository platform (Pure), the registration workflow and last but not least the results since DTU switched to centralized research registration....

  16. A survey of medical image registration - under review.

    Science.gov (United States)

    Viergever, Max A; Maintz, J B Antoine; Klein, Stefan; Murphy, Keelin; Staring, Marius; Pluim, Josien P W

    2016-10-01

    A retrospective view on the past two decades of the field of medical image registration is presented, guided by the article "A survey of medical image registration" (Maintz and Viergever, 1998). It shows that the classification of the field introduced in that article is still usable, although some modifications to do justice to advances in the field would be due. The main changes over the last twenty years are the shift from extrinsic to intrinsic registration, the primacy of intensity-based registration, the breakthrough of nonlinear registration, the progress of inter-subject registration, and the availability of generic image registration software packages. Two problems that were called urgent already 20 years ago, are even more urgent nowadays: Validation of registration methods, and translation of results of image registration research to clinical practice. It may be concluded that the field of medical image registration has evolved, but still is in need of further development in various aspects.

  17. RRS: Replica Registration Service for Data Grids

    Energy Technology Data Exchange (ETDEWEB)

    Shoshani, Arie; Sim, Alex; Stockinger, Kurt

    2005-07-15

    Over the last few years various scientific experiments and Grid projects have developed different catalogs for keeping track of their data files. Some projects use specialized file catalogs, others use distributed replica catalogs to reference files at different locations. Due to this diversity of catalogs, it is very hard to manage files across Grid projects, or to replace one catalog with another. In this paper we introduce a new Grid service called the Replica Registration Service (RRS). It can be thought of as an abstraction of the concepts for registering files and their replicas. In addition to traditional single file registration operations, the RRS supports collective file registration requests and keeps persistent registration queues. This approach is of particular importance for large-scale usage where thousands of files are copied and registered. Moreover, the RRS supports a set of error directives that are triggered in case of registration failures. Our goal is to provide a single uniform interface for various file catalogs to support the registration of files across multiple Grid projects, and to make Grid clients oblivious to the specific catalog used.

  18. Multi-Modal Robust Inverse-Consistent Linear Registration

    OpenAIRE

    Wachinger, Christian; Golland, Polina; Magnain, Caroline; Fischl, Bruce; Reuter, Martin

    2014-01-01

    Registration performance can significantly deteriorate when image regions do not comply with model assumptions. Robust estimation improves registration accuracy by reducing or ignoring the contribution of voxels with large intensity differences, but existing approaches are limited to monomodal registration. In this work, we propose a robust and inverse-consistent technique for crossmodal, affine image registration. The algorithm is derived from a contextual framework of image registration. Th...

  19. Position tracking of moving liver lesion based on real-time registration between 2D ultrasound and 3D preoperative images

    Energy Technology Data Exchange (ETDEWEB)

    Weon, Chijun; Hyun Nam, Woo; Lee, Duhgoon; Ra, Jong Beom, E-mail: jbra@kaist.ac.kr [Department of Electrical Engineering, KAIST, Daejeon 305-701 (Korea, Republic of); Lee, Jae Young [Department of Radiology, Seoul National University Hospital, Seoul 110-744 (Korea, Republic of)

    2015-01-15

    Purpose: Registration between 2D ultrasound (US) and 3D preoperative magnetic resonance (MR) (or computed tomography, CT) images has been studied recently for US-guided intervention. However, the existing techniques have some limits, either in the registration speed or the performance. The purpose of this work is to develop a real-time and fully automatic registration system between two intermodal images of the liver, and subsequently an indirect lesion positioning/tracking algorithm based on the registration result, for image-guided interventions. Methods: The proposed position tracking system consists of three stages. In the preoperative stage, the authors acquire several 3D preoperative MR (or CT) images at different respiratory phases. Based on the transformations obtained from nonrigid registration of the acquired 3D images, they then generate a 4D preoperative image along the respiratory phase. In the intraoperative preparatory stage, they properly attach a 3D US transducer to the patient’s body and fix its pose using a holding mechanism. They then acquire a couple of respiratory-controlled 3D US images. Via the rigid registration of these US images to the 3D preoperative images in the 4D image, the pose information of the fixed-pose 3D US transducer is determined with respect to the preoperative image coordinates. As feature(s) to use for the rigid registration, they may choose either internal liver vessels or the inferior vena cava. Since the latter is especially useful in patients with a diffuse liver disease, the authors newly propose using it. In the intraoperative real-time stage, they acquire 2D US images in real-time from the fixed-pose transducer. For each US image, they select candidates for its corresponding 2D preoperative slice from the 4D preoperative MR (or CT) image, based on the predetermined pose information of the transducer. The correct corresponding image is then found among those candidates via real-time 2D registration based on a

  20. TU-B-19A-01: Image Registration II: TG132-Quality Assurance for Image Registration

    International Nuclear Information System (INIS)

    AAPM Task Group 132 was charged with a review of the current approaches and solutions for image registration in radiotherapy and to provide recommendations for quality assurance and quality control of these clinical processes. As the results of image registration are always used as the input of another process for planning or delivery, it is important for the user to understand and document the uncertainty associate with the algorithm in general and the Result of a specific registration. The recommendations of this task group, which at the time of abstract submission are currently being reviewed by the AAPM, include the following components. The user should understand the basic image registration techniques and methods of visualizing image fusion. The disclosure of basic components of the image registration by commercial vendors is critical in this respect. The physicists should perform end-to-end tests of imaging, registration, and planning/treatment systems if image registration is performed on a stand-alone system. A comprehensive commissioning process should be performed and documented by the physicist prior to clinical use of the system. As documentation is important to the safe implementation of this process, a request and report system should be integrated into the clinical workflow. Finally, a patient specific QA practice should be established for efficient evaluation of image registration results. The implementation of these recommendations will be described and illustrated during this educational session. Learning Objectives: Highlight the importance of understanding the image registration techniques used in their clinic. Describe the end-to-end tests needed for stand-alone registration systems. Illustrate a comprehensive commissioning program using both phantom data and clinical images. Describe a request and report system to ensure communication and documentation. Demonstrate an clinically-efficient patient QA practice for efficient evaluation of image

  1. TU-B-19A-01: Image Registration II: TG132-Quality Assurance for Image Registration

    Energy Technology Data Exchange (ETDEWEB)

    Brock, K [University of Michigan, Ann Arbor, MI (United States); Mutic, S [Washington University School of Medicine, Saint Louis, MO (United States)

    2014-06-15

    AAPM Task Group 132 was charged with a review of the current approaches and solutions for image registration in radiotherapy and to provide recommendations for quality assurance and quality control of these clinical processes. As the results of image registration are always used as the input of another process for planning or delivery, it is important for the user to understand and document the uncertainty associate with the algorithm in general and the Result of a specific registration. The recommendations of this task group, which at the time of abstract submission are currently being reviewed by the AAPM, include the following components. The user should understand the basic image registration techniques and methods of visualizing image fusion. The disclosure of basic components of the image registration by commercial vendors is critical in this respect. The physicists should perform end-to-end tests of imaging, registration, and planning/treatment systems if image registration is performed on a stand-alone system. A comprehensive commissioning process should be performed and documented by the physicist prior to clinical use of the system. As documentation is important to the safe implementation of this process, a request and report system should be integrated into the clinical workflow. Finally, a patient specific QA practice should be established for efficient evaluation of image registration results. The implementation of these recommendations will be described and illustrated during this educational session. Learning Objectives: Highlight the importance of understanding the image registration techniques used in their clinic. Describe the end-to-end tests needed for stand-alone registration systems. Illustrate a comprehensive commissioning program using both phantom data and clinical images. Describe a request and report system to ensure communication and documentation. Demonstrate an clinically-efficient patient QA practice for efficient evaluation of image

  2. 77 FR 66920 - Registration of Claims to Copyright: Group Registration of Serial Issues Filed Electronically

    Science.gov (United States)

    2012-11-08

    ... of Claims to Copyright, 72 FR 36883 (July 6, 2007). When this electronic system was implemented, it... certain serial publications. 55 FR 50556 (December 7, 1990). Under these regulations, issues of serials... Copyright Office 37 CFR Part 202 Registration of Claims to Copyright: Group Registration of Serial...

  3. 16 CFR 1130.8 - Requirements for Web site registration or alternative e-mail registration.

    Science.gov (United States)

    2010-01-01

    ... alternative e-mail registration. 1130.8 Section 1130.8 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION... PRODUCTS (Eff. June 28, 2010) § 1130.8 Requirements for Web site registration or alternative e-mail... number, e-mail address, product model name and number, and the date of manufacture. The...

  4. An SPM8-Based Approach for Attenuation Correction Combining Segmentation and Nonrigid Template Formation: Application to Simultaneous PET/MR Brain Imaging

    DEFF Research Database (Denmark)

    Izquierdo-Garcia, David; Hansen, Adam E; Förster, Stefan;

    2014-01-01

    . The method was validated on 16 new subjects with brain tumors (n = 12) or mild cognitive impairment (n = 4) who underwent CT and PET/MR scans. The μ maps and corresponding reconstructed PET images were compared with those obtained using the gold standard CT-based approach and the Dixon-based method available...... on the Biograph mMR scanner. Relative change (RC) images were generated in each case, and voxel- and region-of-interest-based analyses were performed. RESULTS: The leave-one-out cross-validation analysis of the data from the 15 atlas-generation subjects showed small errors in brain linear attenuation coefficients....../MR scanners. METHODS: Coregistered anatomic MR and CT images of 15 glioblastoma subjects were used to generate the templates. The MR images from these subjects were first segmented into 6 tissue classes (gray matter, white matter, cerebrospinal fluid, bone, soft tissue, and air), which were then nonrigidly...

  5. Ab initio effective rotational and rovibrational Hamiltonians for non-rigid systems via curvilinear second order vibrational M{\\o}ller-Plesset perturbation theory

    CERN Document Server

    Changala, P Bryan

    2016-01-01

    We present a perturbative method for ab initio calculations of rotational and rovibrational effective Hamiltonians of both rigid and non-rigid molecules. Our approach is based on a curvilinear implementation of second order vibrational M{\\o}ller-Plesset perturbation theory (VMP2) extended to include rotational effects via a second order contact transformation. Though more expensive, this approach is significantly more accurate than standard second order vibrational perturbation theory (VPT2) for systems that are poorly described to zeroth order by rectilinear normal mode harmonic oscillators. We apply this method and demonstrate its accuracy on two molecules: Si$_2$C, a quasilinear triatomic with significant bending anharmonicity, and CH$_3$NO$_2$, which contains a completely unhindered methyl rotor. In addition to these two examples, we discuss several key technical aspects of the method, including an efficient implementation of Eckart and quasi-Eckart frame embedding that does not rely on numerical finite d...

  6. Fractional Regularization Term for Variational Image Registration

    Directory of Open Access Journals (Sweden)

    Rafael Verdú-Monedero

    2009-01-01

    Full Text Available Image registration is a widely used task of image analysis with applications in many fields. Its classical formulation and current improvements are given in the spatial domain. In this paper a regularization term based on fractional order derivatives is formulated. This term is defined and implemented in the frequency domain by translating the energy functional into the frequency domain and obtaining the Euler-Lagrange equations which minimize it. The new regularization term leads to a simple formulation and design, being applicable to higher dimensions by using the corresponding multidimensional Fourier transform. The proposed regularization term allows for a real gradual transition from a diffusion registration to a curvature registration which is best suited to some applications and it is not possible in the spatial domain. Results with 3D actual images show the validity of this approach.

  7. Onboard Image Registration from Invariant Features

    Science.gov (United States)

    Wang, Yi; Ng, Justin; Garay, Michael J.; Burl, Michael C

    2008-01-01

    This paper describes a feature-based image registration technique that is potentially well-suited for onboard deployment. The overall goal is to provide a fast, robust method for dynamically combining observations from multiple platforms into sensors webs that respond quickly to short-lived events and provide rich observations of objects that evolve in space and time. The approach, which has enjoyed considerable success in mainstream computer vision applications, uses invariant SIFT descriptors extracted at image interest points together with the RANSAC algorithm to robustly estimate transformation parameters that relate one image to another. Experimental results for two satellite image registration tasks are presented: (1) automatic registration of images from the MODIS instrument on Terra to the MODIS instrument on Aqua and (2) automatic stabilization of a multi-day sequence of GOES-West images collected during the October 2007 Southern California wildfires.

  8. Mass preserving image registration for lung CT

    DEFF Research Database (Denmark)

    Gorbunova, Vladlena; Sporring, Jon; Lo, Pechin;

    2012-01-01

    on four groups of data: 44 pairs of longitudinal inspiratory chest CT scans with small difference in lung volume; 44 pairs of longitudinal inspiratory chest CT scans with large difference in lung volume; 16 pairs of expiratory and inspiratory CT scans; and 5 pairs of images extracted at end exhale and end...... inhale phases of 4D-CT images. Registration errors, measured as the average distance between vessel tree centerlines in the matched images, are significantly lower for the proposed mass preserving image registration method in the second, third and fourth group, while there is no statistically significant......This paper presents a mass preserving image registration algorithm for lung CT images. To account for the local change in lung tissue intensity during the breathing cycle, a tissue appearance model based on the principle of preservation of total lung mass is proposed. This model is incorporated...

  9. Serial volumetric registration of pulmonary CT studies

    Science.gov (United States)

    Silva, José Silvestre; Silva, Augusto; Sousa Santos, Beatriz

    2008-03-01

    Detailed morphological analysis of pulmonary structures and tissue, provided by modern CT scanners, is of utmost importance as in the case of oncological applications both for diagnosis, treatment, and follow-up. In this case, a patient may go through several tomographic studies throughout a period of time originating volumetric sets of image data that must be appropriately registered in order to track suspicious radiological findings. The structures or regions of interest may change their position or shape in CT exams acquired at different moments, due to postural, physiologic or pathologic changes, so, the exams should be registered before any follow-up information can be extracted. Postural mismatching throughout time is practically impossible to avoid being particularly evident when imaging is performed at the limiting spatial resolution. In this paper, we propose a method for intra-patient registration of pulmonary CT studies, to assist in the management of the oncological pathology. Our method takes advantage of prior segmentation work. In the first step, the pulmonary segmentation is performed where trachea and main bronchi are identified. Then, the registration method proceeds with a longitudinal alignment based on morphological features of the lungs, such as the position of the carina, the pulmonary areas, the centers of mass and the pulmonary trans-axial principal axis. The final step corresponds to the trans-axial registration of the corresponding pulmonary masked regions. This is accomplished by a pairwise sectional registration process driven by an iterative search of the affine transformation parameters leading to optimal similarity metrics. Results with several cases of intra-patient, intra-modality registration, up to 7 time points, show that this method provides accurate registration which is needed for quantitative tracking of lesions and the development of image fusion strategies that may effectively assist the follow-up process.

  10. 3D-2D registration for surgical guidance: effect of projection view angles on registration accuracy

    Science.gov (United States)

    Uneri, A.; Otake, Y.; Wang, A. S.; Kleinszig, G.; Vogt, S.; Khanna, A. J.; Siewerdsen, J. H.

    2014-01-01

    An algorithm for intensity-based 3D-2D registration of CT and x-ray projections is evaluated, specifically using single- or dual-projection views to provide 3D localization. The registration framework employs the gradient information similarity metric and covariance matrix adaptation evolution strategy to solve for the patient pose in six degrees of freedom. Registration performance was evaluated in an anthropomorphic phantom and cadaver, using C-arm projection views acquired at angular separation, Δθ, ranging from ˜0°-180° at variable C-arm magnification. Registration accuracy was assessed in terms of 2D projection distance error and 3D target registration error (TRE) and compared to that of an electromagnetic (EM) tracker. The results indicate that angular separation as small as Δθ ˜10°-20° achieved TRE <2 mm with 95% confidence, comparable or superior to that of the EM tracker. The method allows direct registration of preoperative CT and planning data to intraoperative fluoroscopy, providing 3D localization free from conventional limitations associated with external fiducial markers, stereotactic frames, trackers and manual registration.

  11. Phase Correlation Based Iris Image Registration Model

    Institute of Scientific and Technical Information of China (English)

    Jun-Zhou Huang; Tie-Niu Tan; Li Ma; Yun-Hong Wang

    2005-01-01

    Iris recognition is one of the most reliable personal identification methods. In iris recognition systems, image registration is an important component. Accurately registering iris images leads to higher recognition rate for an iris recognition system. This paper proposes a phase correlation based method for iris image registration with sub-pixel accuracy.Compared with existing methods, it is insensitive to image intensity and can compensate to a certain extent the non-linear iris deformation caused by pupil movement. Experimental results show that the proposed algorithm has an encouraging performance.

  12. Effects of spatial resolution on image registration

    Science.gov (United States)

    Zhao, Can; Carass, Aaron; Jog, Amod; Prince, Jerry L.

    2016-03-01

    This paper presents a theoretical analysis of the effect of spatial resolution on image registration. Based on the assumption of additive Gaussian noise on the images, the mean and variance of the distribution of the sum of squared differences (SSD) were estimated. Using these estimates, we evaluate a distance between the SSD distributions of aligned images and non-aligned images. The experimental results show that by matching the resolutions of the moving and fixed images one can get a better image registration result. The results agree with our theoretical analysis of SSD, but also suggest that it may be valid for mutual information as well.

  13. MI image registration using prior knowledge

    CERN Document Server

    Jacquet, W; de Groen, P

    2007-01-01

    Subtraction of aligned images is a means to asses changes in a wide variety of clinical applications. In this paper the information theoretical origin of Mutual Information is explored. The parallelism between the problem of image registration and its characterization as a communication channel is found to be limiting. The concept of Mutual Information (MI) is extended to Focussed Mutual Information (FMI) to incorporate prior knowledge. Several methodologies are proposed to address specific registration problems, incorporating FMI. These methods are demonstrated by means of some elucidating examples.

  14. Evaluation of Brownian warps for shape alignment

    Science.gov (United States)

    Nielsen, Mads

    2007-03-01

    Many methods are used for warping images to non-rigidly register shapes and objects in between medical images in inter- and intra-patient studies. In landmark-based registration linear methods like thin-plate- or b-splines are often used. These linear methods suffer from a number of theoretical deficiencies: they may break or tear apart the shapes, they are not source-destination symmetric, and may not be invertible. Theoretically more satisfactory models using diffeomorphic approaches like "Large Deformations" and "Brownian warps" have earlier proved (in theory and practice) to remove these deficiencies. In this paper we show that the maximum-likelihood Brownian Warps also generalize better in the case of matching fractured vertebrae to normal vertebrae. X-rays of 10 fractured and 1 normal vertebrae have been annotated by a trained radiologist by 6 so-called height points used for fracture scoring, and by the full boundary. The fractured vertebrae have been registered to the normal vertebra using only the 6 height points as landmarks. After registration the Hausdorff distance between the boundaries is measured. The registrations based on Brownian warps show a significantly lower distance to the original boundary.

  15. SU-E-J-66: Significant Anatomical and Dosimetric Changes Observed with the Pharyngeal Constrictor During Head and Neck Radiotherapy Elicited From Daily Deformable Image Registration and Dose Accumulation

    Energy Technology Data Exchange (ETDEWEB)

    Kumarasiri, A; Siddiqui, F; Liu, C; Kamal, M; Fraser, C; Chetty, I; Kim, J [Henry Ford Health System, Detroit, MI (United States)

    2015-06-15

    Purpose: To evaluate the anatomical changes and associated dosimetric consequences to the pharyngeal constrictor (PC) that occurs during head and neck radiotherapy (H&N RT). Methods: A cohort of 13 oro-pharyngeal cancer patients, who had daily CBCT’s for localization, was retrospectively studied. On every 5th CBCT, PC was manually delineated by a radiation oncologist. The anterior-posterior PC thickness was measured at the C3 level. Delivered dose to PC was estimated by calculating daily doses on CBCT’s, and accumulating to corresponding planning CT images. For accumulation, a parameter-optimized B- spline-based deformable image registration algorithm (Elastix) was used, in conjunction with an energy-mass mapping dose transfer algorithm. Mean and maximum dose (Dmean, Dmax) to PC was determined and compared with corresponding planned quantities. Results: The mean (±standard deviation) volume increase (ΔV) and thickness increase (Δt) over the course of 35 total fractions were 54±33% (11.9±7.6 cc), and 63±39% (2.9±1.9 mm), respectively. The resultant cumulative mean dose increase from planned dose to PC (ΔDmean) was 1.4±1.3% (0.9±0.8 Gy), while the maximum dose increase (ΔDmax) was 0.0±1.6% (0.0±1.1 Gy). Patients with adaptive replanning (n=6) showed a smaller mean dose increase than those without (n=7); 0.5±0.2% (0.3±0.1 Gy) vs. 2.2±1.4% (1.4±0.9 Gy). There was a statistically significant (p<0.0001) strong correlation between ΔDmean and Δt (Pearson coefficient r=0.78), and a moderate-to-strong correlation (r=0.52) between ΔDmean and ΔV. Correlation between ΔDmean and weight loss ΔW (r=0.1), as well as ΔV and ΔW (r=0.2) were negligible. Conclusion: Patients were found to undergo considerable anatomical changes to pharyngeal constrictor during H&N RT, resulting in non-negligible dose deviations from intended dose. Results are indicative that pharyngeal constrictor thickness, measured at C3 level, is a good predictor for the dose change to

  16. The registration of complications in surgery : A learning curve

    NARCIS (Netherlands)

    Veen, EJ; Janssen-Heijnen, MLG; Roukema, JA

    2005-01-01

    Registration of complications in surgery is an important method used for quality improvement. Unfortunately many different definitions and classification systems have been used, which influences the interpretation and the outcome of complication registration. Since 1986 complications have been regis

  17. Fast Registration of Cardiac Perfusion MRI

    DEFF Research Database (Denmark)

    Stegmann, Mikkel Bille; Larsson, Henrik B. W.

    2003-01-01

    This abstract presents a novel method for registration of cardiac perfusion MRI sequences. By performing complex analyses of variance and clustering in an annotated training set off-line, our method provides real-time segmentation in an on-line setting. This renders the method feasible for live...

  18. 2016 Joint Universities Accelerator School (JUAS) - Registrations

    CERN Multimedia

    2015-01-01

    The registrations for the 2016 session of the Joint Universities Accelerator School (JUAS) are now open.   Applications are welcome from second-year Master and PhD and for physicists wishing to further their knowledge in this particular field. The deadline for submission of the full application form is 30 October 2015.

  19. 75 FR 6656 - Pesticide Product; Registration Application

    Science.gov (United States)

    2010-02-10

    ... AGENCY Pesticide Product; Registration Application AGENCY: Environmental Protection Agency (EPA). ACTION: Notice. SUMMARY: This notice announces receipt of an application to register a new use for a pesticide... the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), as amended. EPA is publishing...

  20. Registration now open for landmark CERN conference

    CERN Multimedia

    2003-01-01

    Journalist registration is now available for the Role of Science in the Information Society (RSIS) conference, to be held at CERN on 8-9 December....RSIS will explore future contributions of science to the information society based on past and present practice (1 page).

  1. 2017 Joint Universities Accelerator School (JUAS) - Registrations

    CERN Multimedia

    2016-01-01

    The registrations for the 2017 session of the Joint Universities Accelerator School (JUAS) are now open.   Applications are welcome from staff, fellows and post-graduate students wishing to further their knowledge in the field. The deadline for submission of the full application form is 16 October 2016.

  2. DEVELOPMENT AND REGISTRATION OF CHIRAL DRUGS

    NARCIS (Netherlands)

    WITTE, DT; ENSING, K; FRANKE, JP; DEZEEUW, RA

    1993-01-01

    In this review we describe the impact of chirality on drug development and registration in the United States, Japan and the European Community. Enantiomers may have differences in their pharmacological profiles, and, therefore, chiral drugs ask for special analytical and pharmacological attention du

  3. 9 CFR 381.179 - Registration.

    Science.gov (United States)

    2010-01-01

    ... poultry, whether intended for human food or other purposes, or engages in the business as a public... ORGANIZATION AND TERMINOLOGY; MANDATORY MEAT AND POULTRY PRODUCTS INSPECTION AND VOLUNTARY INSPECTION AND CERTIFICATION POULTRY PRODUCTS INSPECTION REGULATIONS Records, Registration, and Reports § 381.179...

  4. 75 FR 76463 - Pesticide Products; Registration Applications

    Science.gov (United States)

    2010-12-08

    ... AGENCY Pesticide Products; Registration Applications AGENCY: Environmental Protection Agency (EPA). ACTION: Notice. SUMMARY: This notice announces receipt of applications to register new uses for pesticide....regulations.gov . Follow the on-line instructions for submitting comments. Mail: Office of Pesticide...

  5. 77 FR 6560 - Pesticide Product Registration Approval

    Science.gov (United States)

    2012-02-08

    ... the Federal Register of June 10, 2009 (74 FR 27541) (FRL-8413-2), which announced that Lubrizol, 29400... AGENCY Pesticide Product Registration Approval AGENCY: Environmental Protection Agency (EPA). ACTION: Notice. SUMMARY: This notice announces Agency approval of an application to register the...

  6. Registrering af biometriske og biologiske personoplysninger

    DEFF Research Database (Denmark)

    Blume, Peter Erik; Herrmann, Janne Rothmar

    2009-01-01

    Med udgangspunkt i menneskeretsdomstolens Marper dom drøftes i artiklen indretningen af dansk rets regler om registrering af fingeraftryk og dna-profil med tilhørende biologisk materiale, og om dommen nødvendiggør ændringer af disse regler....

  7. Reflectance and fluorescence hyperspectral elastic image registration

    Science.gov (United States)

    Lange, Holger; Baker, Ross; Hakansson, Johan; Gustafsson, Ulf P.

    2004-05-01

    Science and Technology International (STI) presents a novel multi-modal elastic image registration approach for a new hyperspectral medical imaging modality. STI's HyperSpectral Diagnostic Imaging (HSDI) cervical instrument is used for the early detection of uterine cervical cancer. A Computer-Aided-Diagnostic (CAD) system is being developed to aid the physician with the diagnosis of pre-cancerous and cancerous tissue regions. The CAD system uses the fusion of multiple data sources to optimize its performance. The key enabling technology for the data fusion is image registration. The difficulty lies in the image registration of fluorescence and reflectance hyperspectral data due to the occurrence of soft tissue movement and the limited resemblance of these types of imagery. The presented approach is based on embedding a reflectance image in the fluorescence hyperspectral imagery. Having a reflectance image in both data sets resolves the resemblance problem and thereby enables the use of elastic image registration algorithms required to compensate for soft tissue movements. Several methods of embedding the reflectance image in the fluorescence hyperspectral imagery are described. Initial experiments with human subject data are presented where a reflectance image is embedded in the fluorescence hyperspectral imagery.

  8. 75 FR 13282 - Pesticide Products; Registration Applications

    Science.gov (United States)

    2010-03-19

    ..., and Quince; and Stone Fruit: Apricot, Cherry, Peach, Nectarine, and Plum. Contact: James M. Stone, (703) 305-7391, stone.james@epa.gov . 5. Registration Numbers: 264-718, 264-719, 264-850. Docket Number..., soursop, biriba, avocado, small vine climbing fruits except fuzzy kiwifruit (crop subgroup 13-07F),...

  9. Deformable image registration with geometric changes

    Institute of Scientific and Technical Information of China (English)

    Yu LIU; Bo ZHU

    2015-01-01

    Geometric changes present a number of difficulties in deformable image registration. In this paper, we propose a global deformation framework to model geometric changes whilst promoting a smooth transformation between source and target images. To achieve this, we have developed an innovative model which significantly reduces the side effects of geometric changes in image registration, and thus improves the registration accuracy. Our key contribution is the introduction of a sparsity-inducing norm, which is typically L1 norm regularization targeting regions where geometric changes occur. This preserves the smoothness of global transformation by eliminating local transformation under different conditions. Numerical solutions are discussed and analyzed to guarantee the stability and fast convergence of our algorithm. To demonstrate the effectiveness and utility of this method, we evaluate it on both synthetic data and real data from traumatic brain injury (TBI). We show that the transformation estimated from our model is able to reconstruct the target image with lower instances of error than a standard elastic registration model.

  10. 77 FR 14362 - Pesticide Products; Registration Applications

    Science.gov (United States)

    2012-03-09

    ..., cucurbits, cereal grains, grass forage, fodder and hay, non-grass animal feeds, herbs and spices, oilseeds.... Potentially affected entities may include, but are not limited to: Crop production (NAICS code 111). Animal...) phosphorothioate at 97%. Proposed Use: formulation purposes. Contact: Lisa Jones, Registration Division, (703)...

  11. 7 CFR 915.120 - Handler registration.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 8 2010-01-01 2010-01-01 false Handler registration. 915.120 Section 915.120 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing... address of applicant; (2) Applicant's principal place(s) of business; (3) Type of business...

  12. 76 FR 66505 - Unified Registration System

    Science.gov (United States)

    2011-10-26

    ... the system.'' The Unified Carrier Registration Act of 2005, subtitle C of title IV of SAFETEA-LU... FR 21993). SAFETEA-LU also amended several definitions that affect the coverage of the URS, amended... originally announced in a May 19, 2005 notice of proposed rulemaking (NPRM). URS is the replacement...

  13. Mass Preserving Registration for lung CT

    DEFF Research Database (Denmark)

    Gorbunova, Vladlena; Lo, Pechin Chien Pau; Loeve, Martin;

    2009-01-01

    intensities due to differences in inspiration level, we propose to adjust the intensity of lung tissue according to the local expansion or compression. An image registration method without intensity adjustment is compared to the proposed method. Both approaches are evaluated on a set of 10 pairs of expiration...

  14. 75 FR 24695 - Pesticide Products; Registration Applications

    Science.gov (United States)

    2010-05-05

    ... AGENCY Pesticide Products; Registration Applications AGENCY: Environmental Protection Agency (EPA). ACTION: Notice. SUMMARY: This notice announces receipt of applications to register new uses for pesticide....regulations.gov . Follow the on-line instructions for submitting comments. Mail: Office of Pesticide...

  15. Nonparametric estimation under censoring and passive registration

    NARCIS (Netherlands)

    Gill, R.D.

    2001-01-01

    The classical random censorship model assumes that we follow an individual continuously up to the time of failure or censoring so observing this time as well as the indicator of its type Under passive registration we only get information on the state of the individual at random observation or regist

  16. Registration of heat capacity mapping mission day and night images

    Science.gov (United States)

    Watson, K.; Hummer-Miller, S.; Sawatzky, D. L.

    1982-01-01

    Registration of thermal images is complicated by distinctive differences in the appearance of day and night features needed as control in the registration process. These changes are unlike those that occur between Landsat scenes and pose unique constraints. Experimentation with several potentially promising techniques has led to selection of a fairly simple scheme for registration of data from the experimental thermal satellite HCMM using an affine transformation. Two registration examples are provided.

  17. 14 CFR 47.51 - Triennial aircraft registration report.

    Science.gov (United States)

    2010-01-01

    ... in the United States; or (iii) A corporation (other than a corporation which is a citizen of the... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Triennial aircraft registration report. 47... AIRCRAFT AIRCRAFT REGISTRATION Certificates of Aircraft Registration § 47.51 Triennial...

  18. Registration of 3D Face Scans with Average Face Models

    NARCIS (Netherlands)

    Salah, A.A.; Alyuz, N.; Akarun, L.

    2008-01-01

    The accuracy of a 3D face recognition system depends on a correct registration that aligns the facial surfaces and makes a comparison possible. The best results obtained so far use a costly one-to-all registration approach, which requires the registration of each facial surface to all faces in the g

  19. 12 CFR 998.2 - Registration and periodic disclosures.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 7 2010-01-01 2010-01-01 false Registration and periodic disclosures. 998.2 Section 998.2 Banks and Banking FEDERAL HOUSING FINANCE BOARD FEDERAL HOME LOAN BANK DISCLOSURES REGISTRATION OF FEDERAL HOME LOAN BANK EQUITY SECURITIES § 998.2 Registration and periodic disclosures....

  20. 28 CFR 811.10 - Changes in registration information.

    Science.gov (United States)

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Changes in registration information. 811... DISTRICT OF COLUMBIA SEX OFFENDER REGISTRATION § 811.10 Changes in registration information. (a)(1) A sex... moves to a different address; (ii) leaves a job or obtains a new job, or leaves a school or enrolls in...

  1. 76 FR 4072 - Registration of Claims of Copyright

    Science.gov (United States)

    2011-01-24

    ... under the ``single unit of publication'' rule of Sec. 202.3(b)(4)(i)(A), the group database registration... 1989. See Registration of Claims to Copyright Registration and Deposit of Databases, 54 FR 13177 (March... Procedure Act states that general notice of proposed rulemaking is not required for rules of...

  2. 47 CFR 17.4 - Antenna structure registration.

    Science.gov (United States)

    2010-10-01

    ... Antenna Structure Registration Number must be weather-resistant and of sufficient size to be easily seen... 47 Telecommunication 1 2010-10-01 2010-10-01 false Antenna structure registration. 17.4 Section 17... ANTENNA STRUCTURES General Information § 17.4 Antenna structure registration. (a) Effective July 1,...

  3. 27 CFR 19.155 - Maintenance of registration file.

    Science.gov (United States)

    2010-04-01

    ... registration file. 19.155 Section 19.155 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND... Spirits Plants § 19.155 Maintenance of registration file. The proprietor shall maintain the registration file in looseleaf form in complete and current condition, readily available at the plant for...

  4. 17 CFR 31.6 - Registration of leverage commodities.

    Science.gov (United States)

    2010-04-01

    ... 17 Commodity and Securities Exchanges 1 2010-04-01 2010-04-01 false Registration of leverage... LEVERAGE TRANSACTIONS § 31.6 Registration of leverage commodities. (a) Registration of leverage commodities. Each leverage commodity upon which a leverage contract is offered for sale or purchase or is sold...

  5. 46 CFR 401.220 - Registration of pilots.

    Science.gov (United States)

    2010-10-01

    ... affecting § 401.220, see the List of CFR Sections Affected, which appears in the Finding Aids section of the... 46 Shipping 8 2010-10-01 2010-10-01 false Registration of pilots. 401.220 Section 401.220 Shipping... Registration of Pilots § 401.220 Registration of pilots. (a) The Director shall determine the number of...

  6. Passenger Vehicle Registrations Rallied in February——registrations reflect auto market tendency

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Passenger vehicles (including vans) registrations year-on-year increased 42.2% in Feb. 2007, reaching 408,570 units. Due to the reason there was a larger sales period before the past Chinese New Year in late of February, thus Feb. 2007 made a rather different tendency than previous years. The registrations exceeded more than 0.2 million compared with the past

  7. National registration of accidents in Iceland.

    Science.gov (United States)

    Olafsson, O; Axelsson, J

    1992-01-01

    Community based registration of accidents has been employed in Iceland from 1987. A form developed in the emergency ward at the city Hospital of Reykjavik has been used for the registration. The following issues have been registered: the type and the seriousness of the injury, treatment, place of accident and time of accident. Health centres in Iceland have been computerized from 1976. At the time being about half of the health centres participate in the registration with the information included in the form as the source. Every health center has its well defined district. The accidents among the inhabitants in each district is registered, while accidents among other people, e.g. tourists, is registered separately. At this moment 183,000 out of a total number of 259,000 inhabitants are covered by the registration, i.e. 71% of the population. In 1989 the frequency of accidents was 198 per 100,000 inhabitants. 26% of the accidents occurred at home, 11% at work, 9% during physical activity, 6% was traffic accidents, whereas the same proportion occurred at school. This registration system has been created as a result of annual conferences on accidents arranged by the Director General of public health since 1984. Representatives for the following parties have been invited; medical doctors working in hospitals and health centres, clinical nurses, physiotherapists, the National Insurance Service, other insurance companies, rescue and ambulance personal, fire departments, the Automobile Association, the communication Council. Local communities members of the parliament, voluntary organizations, e.g. Red Cross, the Sea Rescue Service and the Aviation Board. This activity has stimulated measures aiming at preventing accidents in several local communities.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1285816

  8. Image registration in gastric emptying studies

    Energy Technology Data Exchange (ETDEWEB)

    Shuter, B.; Cooper, R.G. [Royal North Shore Hospital, Crows Nest, NSW (Australia). Dept of Nuclear Medicine

    1998-03-01

    Full text: We have previously shown that image registration, based upon a two-dimensional cross-correlation (CC) of logarithmic Laplacian images (LLI), corrected motion in biliary studies in up to 90% of cases with minimal artifact. We have now applied the same technique to gastric emptying studies (GES). GES were acquired on an LFOV gamma camera over a two-hour period as 20-26 pairs of anterior-posterior frames (30 second duration and 64 x 64 matrix) for both solid and liquid components. All images were manually registered so that the solid contents of the stomach lay within an operator-drawn ROI. The anterior images of the solid component for 30 randomly selected patients were subjected to further image registration using CC of LLI, CC of raw images (Rl) (a common approach to image registration) and CC of Laplacian images (Ll). All images were aligned to the third image of the study, on which an ROI was drawn to outline the stomach. The number of images in which stomach counts appeared outside this ROI were tallied, in the original and all re-registered studies. Maximum displacements in X/Y position between images of studies registered by the LLI and Rl methods were also computed to directly compare positional accuracy. Stomachs partially exceeded the limits of the ROI in 27, 9, 53 and 54 frames (total of 710) in the original, LLI, Rl and Ll studies respectively. There were 4, 1, 6 and 7 studies with misregistered stomachs on more than 2 frames. Frames in seven Rl studies differed from the LLI studies in X/Y position by 3 pixels or more. Cross-correlation using LLI was the only method which improved upon the original manual registration. The Rl and Ll methods increased the number of misregistered frames. We conclude that in gastric emptying studies, as in biliary studies, object tracking by CC of LLI is the method of choice for image registration.

  9. Sci—Thur AM: YIS - 11: Estimation of Bladder-Wall Cumulative Dose in Multi-Fraction Image-Based Gynaecological Brachytherapy Using Deformable Point Set Registration

    Energy Technology Data Exchange (ETDEWEB)

    Zakariaee, R [Physics Department, University of British Columbia, Vancouver, BC (Canada); Brown, C J; Hamarneh, G [School of Computing Science, Simon Fraser University, Burnaby, BC (Canada); Parsons, C A; Spadinger, I [British Columbia Cancer Agency, Vancouver, BC (Canada)

    2014-08-15

    Dosimetric parameters based on dose-volume histograms (DVH) of contoured structures are routinely used to evaluate dose delivered to target structures and organs at risk. However, the DVH provides no information on the spatial distribution of the dose in situations of repeated fractions with changes in organ shape or size. The aim of this research was to develop methods to more accurately determine geometrically localized, cumulative dose to the bladder wall in intracavitary brachytherapy for cervical cancer. The CT scans and treatment plans of 20 cervical cancer patients were used. Each patient was treated with five high-dose-rate (HDR) brachytherapy fractions of 600cGy prescribed dose. The bladder inner and outer surfaces were delineated using MIM Maestro software (MIM Software Inc.) and were imported into MATLAB (MathWorks) as 3-dimensional point clouds constituting the “bladder wall”. A point-set registration toolbox for MATLAB, Coherent Point Drift (CPD), was used to non-rigidly transform the bladder-wall points from four of the fractions to the coordinate system of the remaining (reference) fraction, which was chosen to be the emptiest bladder for each patient. The doses were accumulated on the reference fraction and new cumulative dosimetric parameters were calculated. The LENT-SOMA toxicity scores of these patients were studied against the cumulative dose parameters. Based on this study, there was no significant correlation between the toxicity scores and the determined cumulative dose parameters.

  10. Sci—Thur AM: YIS - 11: Estimation of Bladder-Wall Cumulative Dose in Multi-Fraction Image-Based Gynaecological Brachytherapy Using Deformable Point Set Registration

    International Nuclear Information System (INIS)

    Dosimetric parameters based on dose-volume histograms (DVH) of contoured structures are routinely used to evaluate dose delivered to target structures and organs at risk. However, the DVH provides no information on the spatial distribution of the dose in situations of repeated fractions with changes in organ shape or size. The aim of this research was to develop methods to more accurately determine geometrically localized, cumulative dose to the bladder wall in intracavitary brachytherapy for cervical cancer. The CT scans and treatment plans of 20 cervical cancer patients were used. Each patient was treated with five high-dose-rate (HDR) brachytherapy fractions of 600cGy prescribed dose. The bladder inner and outer surfaces were delineated using MIM Maestro software (MIM Software Inc.) and were imported into MATLAB (MathWorks) as 3-dimensional point clouds constituting the “bladder wall”. A point-set registration toolbox for MATLAB, Coherent Point Drift (CPD), was used to non-rigidly transform the bladder-wall points from four of the fractions to the coordinate system of the remaining (reference) fraction, which was chosen to be the emptiest bladder for each patient. The doses were accumulated on the reference fraction and new cumulative dosimetric parameters were calculated. The LENT-SOMA toxicity scores of these patients were studied against the cumulative dose parameters. Based on this study, there was no significant correlation between the toxicity scores and the determined cumulative dose parameters

  11. Quantitative assessment of global and regional air trappings using non-rigid registration and regional specific volume change of inspiratory/expiratory CT scans: Studies on healthy volunteers and asthmatics

    International Nuclear Information System (INIS)

    The purpose of this study was to compare air trapping in healthy volunteers with asthmatics using pulmonary function test and quantitative data, such as specific volume change from paired inspiratory CT and registered expiratory CT. Sixteen healthy volunteers and 9 asthmatics underwent paired inspiratory/expiratory CT. DeltaSV, which represents the ratio of air fraction released after exhalation, was measured with paired inspiratory and anatomically registered expiratory CT scans. Air trapping indexes, DeltaSV0.4 and DeltaSV0.5, were defined as volume fraction of lung below 0.4 and 0.5 DeltaSV, respectively. To assess the gravity effect of air-trapping, DeltaSV values of anterior and posterior lung at three different levels were measured and DeltaSV ratio of anterior lung to posterior lung was calculated. Color-coded DeltaSV map of the whole lung was generated and visually assessed. Mean DeltaSV, DeltaSV0.4, and DeltaSV0.5 were compared between healthy volunteers and asthmatics. In asthmatics, correlation between air trapping indexes and clinical parameters were assessed. Mean DeltaSV, DeltaSV0.4, and DeltaSV0.5 in asthmatics were significantly higher than those in healthy volunteer group (all p < 0.05). DeltaSV values in posterior lung in asthmatics were significantly higher than those in healthy volunteer group (p = 0.049). In asthmatics, air trapping indexes, such as DeltaSV0.5 and DeltaSV0.4, showed negative strong correlation with FEF25-75, FEV1, and FEV1/FVC. DeltaSV map of asthmatics showed abnormal geographic pattern in 5 patients (55.6%) and disappearance of anterior-posterior gradient in 3 patients (33.3%). Quantitative assessment of DeltaSV (the ratio of air fraction released after exhalation) shows the difference in extent of air trapping between health volunteers and asthmatics.

  12. Quantitative assessment of global and regional air trappings using non-rigid registration and regional specific volume change of inspiratory/expiratory CT scans: Studies on healthy volunteers and asthmatics

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eun Sol; Seo, Joon Beom; Lee, Hyun Joo; Chae, Eun Jin; Lee, Sang Min; Oh, Sang Young; Kim, Nam Kug [Dept. of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of)

    2015-06-15

    The purpose of this study was to compare air trapping in healthy volunteers with asthmatics using pulmonary function test and quantitative data, such as specific volume change from paired inspiratory CT and registered expiratory CT. Sixteen healthy volunteers and 9 asthmatics underwent paired inspiratory/expiratory CT. DeltaSV, which represents the ratio of air fraction released after exhalation, was measured with paired inspiratory and anatomically registered expiratory CT scans. Air trapping indexes, DeltaSV0.4 and DeltaSV0.5, were defined as volume fraction of lung below 0.4 and 0.5 DeltaSV, respectively. To assess the gravity effect of air-trapping, DeltaSV values of anterior and posterior lung at three different levels were measured and DeltaSV ratio of anterior lung to posterior lung was calculated. Color-coded DeltaSV map of the whole lung was generated and visually assessed. Mean DeltaSV, DeltaSV0.4, and DeltaSV0.5 were compared between healthy volunteers and asthmatics. In asthmatics, correlation between air trapping indexes and clinical parameters were assessed. Mean DeltaSV, DeltaSV0.4, and DeltaSV0.5 in asthmatics were significantly higher than those in healthy volunteer group (all p < 0.05). DeltaSV values in posterior lung in asthmatics were significantly higher than those in healthy volunteer group (p = 0.049). In asthmatics, air trapping indexes, such as DeltaSV0.5 and DeltaSV0.4, showed negative strong correlation with FEF25-75, FEV1, and FEV1/FVC. DeltaSV map of asthmatics showed abnormal geographic pattern in 5 patients (55.6%) and disappearance of anterior-posterior gradient in 3 patients (33.3%). Quantitative assessment of DeltaSV (the ratio of air fraction released after exhalation) shows the difference in extent of air trapping between health volunteers and asthmatics.

  13. Research on Intensity and Shape Based Non-rigid Image Registration%基于灰度和形状的非刚性图像配准算法的研究

    Institute of Scientific and Technical Information of China (English)

    林相波; 邱天爽; RUAN Su; Frédéric Morain-Nicolier

    2009-01-01

    提出一种新的灰度和形状信息相结合的全自动同模态医学图像非刚性配准-分割算法,将欧氏距离表示的形状信息融入基于灰度的配准算法中,构造出新的代价函数.该算法在医学图像多目标分割的应用中,能够较好地完成灰度相近、边缘模糊、间距较小的不同结构的分割.对5组真实脑部MRI图像进行分割脑深层灰质结构的实验,结果表明,本算法优于基于灰度信息的图像配准算法.

  14. Cardiac motion compensation and resolution modeling in simultaneous PET-MR: a cardiac lesion detection study

    Science.gov (United States)

    Petibon, Y.; Ouyang, J.; Zhu, X.; Huang, C.; Reese, T. G.; Chun, S. Y.; Li, Q.; El Fakhri, G.

    2013-04-01

    Cardiac motion and partial volume effects (PVE) are two of the main causes of image degradation in cardiac PET. Motion generates artifacts and blurring while PVE lead to erroneous myocardial activity measurements. Newly available simultaneous PET-MR scanners offer new possibilities in cardiac imaging as MRI can assess wall contractility while collecting PET perfusion data. In this perspective, we develop a list-mode iterative reconstruction framework incorporating both tagged-MR derived non-rigid myocardial wall motion and position dependent detector point spread function (PSF) directly into the PET system matrix. In this manner, our algorithm performs both motion ‘deblurring’ and PSF deconvolution while reconstructing images with all available PET counts. The proposed methods are evaluated in a beating non-rigid cardiac phantom whose hot myocardial compartment contains small transmural and non-transmural cold defects. In order to accelerate imaging time, we investigate collecting full and half k-space tagged MR data to obtain tagged volumes that are registered using non-rigid B-spline registration to yield wall motion information. Our experimental results show that tagged-MR based motion correction yielded an improvement in defect/myocardium contrast recovery of 34-206% as compared to motion uncorrected studies. Likewise, lesion detectability improved by respectively 115-136% and 62-235% with MR-based motion compensation as compared to gating and no motion correction and made it possible to distinguish non-transmural from transmural defects, which has clinical significance given the inherent limitations of current single modality imaging in identifying the amount of residual ischemia. The incorporation of PSF modeling within the framework of MR-based motion compensation significantly improved defect/myocardium contrast recovery (5.1-8.5%, p defect detectability (39-56%, p < 0.01). No statistical difference was found in PET contrast and lesion detectability

  15. High performance deformable image registration algorithms for manycore processors

    CERN Document Server

    Shackleford, James; Sharp, Gregory

    2013-01-01

    High Performance Deformable Image Registration Algorithms for Manycore Processors develops highly data-parallel image registration algorithms suitable for use on modern multi-core architectures, including graphics processing units (GPUs). Focusing on deformable registration, we show how to develop data-parallel versions of the registration algorithm suitable for execution on the GPU. Image registration is the process of aligning two or more images into a common coordinate frame and is a fundamental step to be able to compare or fuse data obtained from different sensor measurements. E

  16. Image registration in high-dimensional feature space

    Science.gov (United States)

    Neemuchwala, Huzefa F.; Hero, Alfred O.

    2005-03-01

    Image registration is a difficult task especially when spurrious image intensity differences and spatial variations between the two images are present. To robustify image registration algorithms to such spurrious variations it can be useful to employ an image registration matching criteria on higher dimensional feature spaces. This paper will present an overviewof our recent work on image registration using high dimensional image features and entropic graph matching criteria. New entropic graph estimates of information divergence measures will be presented. We will demonstrate the advantage of our approach for ultrasound breast image registration.

  17. A New Extended Projection-Based Image Registration Algorithm

    Institute of Scientific and Technical Information of China (English)

    CHENHuafu; YAODezhong

    2005-01-01

    In the presence of fixed -pattern noise, the projection-based image registration technique is effective but its implementation is only confined to translation registration. Presented in this paper is an extended projectionbased image registration technique in which, by rearranging the projections of images, the image registration is implemented in two steps: rotation and translation, to accomplish two-dimensional (2-D) image registration. Thisapproach transforms the general 2-D optimization procedure into an 1-D projection optimization, thus considerably reducing the amount of computation. The validity ofthe new method is testified by simulation experiment.

  18. Image Segmentation, Registration, Compression, and Matching

    Science.gov (United States)

    Yadegar, Jacob; Wei, Hai; Yadegar, Joseph; Ray, Nilanjan; Zabuawala, Sakina

    2011-01-01

    A novel computational framework was developed of a 2D affine invariant matching exploiting a parameter space. Named as affine invariant parameter space (AIPS), the technique can be applied to many image-processing and computer-vision problems, including image registration, template matching, and object tracking from image sequence. The AIPS is formed by the parameters in an affine combination of a set of feature points in the image plane. In cases where the entire image can be assumed to have undergone a single affine transformation, the new AIPS match metric and matching framework becomes very effective (compared with the state-of-the-art methods at the time of this reporting). No knowledge about scaling or any other transformation parameters need to be known a priori to apply the AIPS framework. An automated suite of software tools has been created to provide accurate image segmentation (for data cleaning) and high-quality 2D image and 3D surface registration (for fusing multi-resolution terrain, image, and map data). These tools are capable of supporting existing GIS toolkits already in the marketplace, and will also be usable in a stand-alone fashion. The toolkit applies novel algorithmic approaches for image segmentation, feature extraction, and registration of 2D imagery and 3D surface data, which supports first-pass, batched, fully automatic feature extraction (for segmentation), and registration. A hierarchical and adaptive approach is taken for achieving automatic feature extraction, segmentation, and registration. Surface registration is the process of aligning two (or more) data sets to a common coordinate system, during which the transformation between their different coordinate systems is determined. Also developed here are a novel, volumetric surface modeling and compression technique that provide both quality-guaranteed mesh surface approximations and compaction of the model sizes by efficiently coding the geometry and connectivity

  19. Research on land registration procedure ontology of China

    Science.gov (United States)

    Zhao, Zhongjun; Du, Qingyun; Zhang, Weiwei; Liu, Tao

    2009-10-01

    Land registration is public act which is to record the state-owned land use right, collective land ownership, collective land use right and land mortgage, servitude, as well as other land rights required the registration according to laws and regulations onto land registering books. Land registration is one of the important government affairs , so it is very important to standardize, optimize and humanize the process of land registration. The management works of organization are realized through a variety of workflows. Process knowledge is in essence a kind of methodology knowledge and a system which including the core and the relational knowledge. In this paper, the ontology is introduced into the field of land registration and management, trying to optimize the flow of land registration, to promote the automation-building and intelligent Service of land registration affairs, to provide humanized and intelligent service for multi-types of users . This paper tries to build land registration procedure ontology by defining the land registration procedure ontology's key concepts which represent the kinds of processes of land registration and mapping the kinds of processes to OWL-S. The land registration procedure ontology shall be the start and the basis of the Web service.

  20. Template-based CTA to x-ray angio rigid registration of coronary arteries in frequency domain with automatic x-ray segmentation

    Energy Technology Data Exchange (ETDEWEB)

    Aksoy, Timur; Unal, Gozde [Sabanci University, Tuzla, Istanbul 34956 (Turkey); Demirci, Stefanie; Navab, Nassir [Computer Aided Medical Procedures (CAMP), Technical University of Munich, Garching, 85748 (Germany); Degertekin, Muzaffer [Yeditepe University Hospital, Istanbul 34752 (Turkey)

    2013-10-15

    patient data; and with ground truth values and landmark distances for the images acquired with a solid phantom vessel. Results validate that rotation recovery in frequency domain is robust against differences in segmentations in two modalities. Distance-map translation is successful in aligning coronary trees with highest possible overlap.Conclusions: Numerical and qualitative results show that single view rigid alignment in projection space is successful. This work can be extended with multiple views to resolve depth ambiguity and with deformable registration to account for nonrigid motion in patient data.

  1. Template-based CTA to x-ray angio rigid registration of coronary arteries in frequency domain with automatic x-ray segmentation

    International Nuclear Information System (INIS)

    with ground truth values and landmark distances for the images acquired with a solid phantom vessel. Results validate that rotation recovery in frequency domain is robust against differences in segmentations in two modalities. Distance-map translation is successful in aligning coronary trees with highest possible overlap.Conclusions: Numerical and qualitative results show that single view rigid alignment in projection space is successful. This work can be extended with multiple views to resolve depth ambiguity and with deformable registration to account for nonrigid motion in patient data

  2. Hospital Registration Process Reengineering Using Simulation Method

    Directory of Open Access Journals (Sweden)

    Qiang Su

    2010-01-01

    Full Text Available With increasing competition, many healthcare organizations have undergone tremendous reform in the last decade aiming to increase efficiency, decrease waste, and reshape the way that care is delivered. This study focuses on the operational efficiency improvement of hospital’s registration process. The operational efficiency related factors including the service process, queue strategy, and queue parameters were explored systematically and illustrated with a case study. Guided by the principle of business process reengineering (BPR, a simulation approach was employed for process redesign and performance optimization. As a result, the queue strategy is changed from multiple queues and multiple servers to single queue and multiple servers with a prepare queue. Furthermore, through a series of simulation experiments, the length of the prepare queue and the corresponding registration process efficiency was quantitatively evaluated and optimized.

  3. Algorithm for Fast Registration of Radar Images

    Directory of Open Access Journals (Sweden)

    Subrata Rakshit

    2002-07-01

    Full Text Available Radar imagery provides an all-weather and 24 h coverage, making it ideal for critical defence applications. In some applications, multiple images acquired of an area need to be registered for further processing. Such situations arise for battlefield surveillance based on satellite imagery. The registration has to be done between an earlier (reference image and a new (live image. For automated surveillance, registration is a prerequisite for change detection. Speed is essential due to large volumes of data involved and the need for quick responses. The registration transformation is quite simple, being mainly a global translation. (Scale and rotation corrections can be applied based on known camera parameters. The challenge lies in the fact that the radar images are not as feature-rich as optical images and the image content variation can be as high as 90 per cent. Even though the change on the ground may not be drastic, seasonal variations can significantly alter the radar signatures of ground, vegetation, and water bodies. This necessitates a novel approach different from the techniques developed for optical images. An algorithm has been developed that leads to fast registration of radar images, even in the presence of specular noise and significant scene content variation. The key features of this approach are adaptability to sensor/terrain types, ability to handle large content variations and false positive rejection. The present work shows that this algorithm allows for various cost-performance trade-offs, making it suitable for a wide variety of applications. The algorithm, in various cost-performance configurations, is tested on a set of ERS images. Results of such tests have been reported, indicating the performance of the algorithm for various cost-performance trade-offs.

  4. Registration and rectification needs of geology

    Science.gov (United States)

    Chavez, P. S., Jr.

    1982-01-01

    Geologic applications of remotely sensed imaging encompass five areas of interest. The five areas include: (1) enhancement and analysis of individual images; (2) work with small area mosaics of imagery which have been map projection rectified to individual quadrangles; (3) development of large area mosaics of multiple images for several counties or states; (4) registration of multitemporal images; and (5) data integration from several sensors and map sources. Examples for each of these types of applications are summarized.

  5. Automated image registration for FDOPA PET studies

    Science.gov (United States)

    Lin, Kang-Ping; Huang, Sung-Cheng; Yu, Dan-Chu; Melega, William; Barrio, Jorge R.; Phelps, Michael E.

    1996-12-01

    In this study, various image registration methods are investigated for their suitability for registration of L-6-[18F]-fluoro-DOPA (FDOPA) PET images. Five different optimization criteria including sum of absolute difference (SAD), mean square difference (MSD), cross-correlation coefficient (CC), standard deviation of pixel ratio (SDPR), and stochastic sign change (SSC) were implemented and Powell's algorithm was used to optimize the criteria. The optimization criteria were calculated either unidirectionally (i.e. only evaluating the criteria for comparing the resliced image 1 with the original image 2) or bidirectionally (i.e. averaging the criteria for comparing the resliced image 1 with the original image 2 and those for the sliced image 2 with the original image 1). Monkey FDOPA images taken at various known orientations were used to evaluate the accuracy of different methods. A set of human FDOPA dynamic images was used to investigate the ability of the methods for correcting subject movement. It was found that a large improvement in performance resulted when bidirectional rather than unidirectional criteria were used. Overall, the SAD, MSD and SDPR methods were found to be comparable in performance and were suitable for registering FDOPA images. The MSD method gave more adequate results for frame-to-frame image registration for correcting subject movement during a dynamic FDOPA study. The utility of the registration method is further demonstrated by registering FDOPA images in monkeys before and after amphetamine injection to reveal more clearly the changes in spatial distribution of FDOPA due to the drug intervention.

  6. Automated experiment for registration of bioelectrical potentials

    Directory of Open Access Journals (Sweden)

    D. V. Chernetchenko

    2013-11-01

    Full Text Available A hardware-software complex automated system of recording bioelectrical potentials, which is based on a USB-device with subsequent processing of signals with PC was developed in this work. We proposed a universal scheme of registration of bioelectrical potentials, which allows one to detect the reaction of biological objects to different stimuli, such as cold, heat, photo- and electrical stimulation, and to different combinations of these stimuli (Motsnyj et al., 2004. They could be applied for deeper understanding of the biological mechanisms of generation of electrical potentials in cells and discovering the accommodation processes of organisms as a whole to these stimuli. The system for registration of bioelectrical potentials consists of hardware and software parts. The software part consists of the client and server sides, which transmit experimental data to the network. The client-side software renders a quantitative analysis and stores the results in a database. An integrated system of registration and biometrical processing was applied for analysis of the electrical responses of maize leaves to heat stimuli. The dynamics of these potentials were studied and a quantitative analysis of the potential level stabilization was made. We found that amplitude relation of responses to the initial response increased and stabilized at the level of 130%. Mathematical models of the plant cell for discovering intracellular mechanisms of biopotentials registration were developed. As a result of modeling, we found that the electrical response of the cells is based on selective conductance of the cell membrane for Н+ and K+ ions. By this way, we show the biophysical relation of plant potentials to intracellular biophysical mechanisms.

  7. A Tutorial on Parametric Image Registration

    OpenAIRE

    Romero, Leonardo; Calderon, Felix

    2007-01-01

    A tutorial, with all the details related to the parametric image registration task, has been presented. Also two new methods (Method 1 and Method 3) are presented besides the classical method to compute derivatives of images. Method 1 computes the image derivatives faster than the other two methods, but it does not give accurate estimations. Methods 2 and 3 take more time because they compute derivatives of the transformed image (at each iteration) while method 1 computes derivatives of the i...

  8. Coarse Fingerprint Registration Using Orientation Fields

    OpenAIRE

    Adnan Amin; Neil Yager

    2005-01-01

    The majority of traditional research into automated fingerprint identification has focused on algorithms using minutiae-based features. However, shortcomings of this approach are becoming apparent due to the difficulty of extracting minutiae points from noisy or low-quality images. Therefore, there has been increasing interest in algorithms based on nonminutiae features in recent years. One vital stage in most fingerprint verification systems is registration, which involves recovering the tr...

  9. Vietnam’s Household Registration System

    OpenAIRE

    World Bank Group; Vietnam Academy of Social Sciences

    2016-01-01

    The household registration system known as ho khau has been a part of the fabric of life in the country for over 50 years. The system was implemented as an instrument of public security, economic planning, and control of migration, at a time when the state played a stronger role in direct management of the economy and the life of its citizens. Although the system has become less rigid over...

  10. Image registration method for medical image sequences

    Science.gov (United States)

    Gee, Timothy F.; Goddard, James S.

    2013-03-26

    Image registration of low contrast image sequences is provided. In one aspect, a desired region of an image is automatically segmented and only the desired region is registered. Active contours and adaptive thresholding of intensity or edge information may be used to segment the desired regions. A transform function is defined to register the segmented region, and sub-pixel information may be determined using one or more interpolation methods.

  11. Automated landmark-guided deformable image registration

    Science.gov (United States)

    Kearney, Vasant; Chen, Susie; Gu, Xuejun; Chiu, Tsuicheng; Liu, Honghuan; Jiang, Lan; Wang, Jing; Yordy, John; Nedzi, Lucien; Mao, Weihua

    2015-01-01

    The purpose of this work is to develop an automated landmark-guided deformable image registration (LDIR) algorithm between the planning CT and daily cone-beam CT (CBCT) with low image quality. This method uses an automated landmark generation algorithm in conjunction with a local small volume gradient matching search engine to map corresponding landmarks between the CBCT and the planning CT. The landmarks act as stabilizing control points in the following Demons deformable image registration. LDIR is implemented on graphics processing units (GPUs) for parallel computation to achieve ultra fast calculation. The accuracy of the LDIR algorithm has been evaluated on a synthetic case in the presence of different noise levels and data of six head and neck cancer patients. The results indicate that LDIR performed better than rigid registration, Demons, and intensity corrected Demons for all similarity metrics used. In conclusion, LDIR achieves high accuracy in the presence of multimodality intensity mismatch and CBCT noise contamination, while simultaneously preserving high computational efficiency.

  12. Discussion on Registration Validity Doctrine of Housing Land Use Right

    Institute of Scientific and Technical Information of China (English)

    Wenli; YU

    2013-01-01

    Relationship between the registration and right change of housing land use right is not clearly stipulated in the Property Law. Land registration involves functions of private law and public law. It is partial to only considering private rights dimension when deciding whether registration validity doctrine or registration confrontation doctrine should be implemented in housing land use right. Compilation of land use planning, implementation of land use control and promotion of arrangement project in rural residential area all rely on sound and complete housing land registration data. To clarify housing land right adscription, eliminate hidden troubles causing housing land dispute and promote the establishment of harmonious countryside can never be achieved without housing land registration data. To carry out registration validity doctrine of housing land use right can effectively guide farmers’ registration behavior and thus build a perfect registration information system of housing land use right. After the cross-village and even cross-town arrangement in rural residential areas, rural acquaintance society has transformed into semi-acquaintance society and even stranger society. Therefore, housing land use right commending its existence with registration in public form has been a necessary choice in legislation.

  13. Image Classifying Registration and Dynamic Region Merging

    Directory of Open Access Journals (Sweden)

    Himadri Nath Moulick

    2013-07-01

    Full Text Available In this paper, we address a complex image registration issue arising when the dependencies between intensities of images to be registered are not spatially homogeneous. Such a situation is frequentlyencountered in medical imaging when a pathology present in one of the images modifies locally intensity dependencies observed on normal tissues. Usual image registration models, which are based on a single global intensity similarity criterion, fail to register such images, as they are blind to local deviations of intensity dependencies. Such a limitation is also encountered in contrast enhanced images where there exist multiple pixel classes having different properties of contrast agent absorption. In this paper, we propose a new model in which the similarity criterion is adapted locally to images by classification of image intensity dependencies. Defined in a Bayesian framework, the similarity criterion is a mixture of probability distributions describing dependencies on two classes. The model also includes a class map which locates pixels of the two classes and weights the two mixture components. The registration problem is formulated both as an energy minimization problem and as a Maximum A Posteriori (MAP estimation problem. It is solved using a gradient descent algorithm. In the problem formulation and resolution, the image deformation and the class map are estimated at the same time, leading to an original combination of registration and classification that we call image classifying registration. Whenever sufficient information about class location is available in applications, the registration can also be performed on its own by fixing a given class map. Finally, we illustrate the interest of our model on two real applications from medical imaging: template-based segmentation of contrast-enhanced images and lesion detection in mammograms. We also conduct an evaluation of our model on simulated medical data and show its ability to take into

  14. Intensity-Based Registration for Lung Motion Estimation

    Science.gov (United States)

    Cao, Kunlin; Ding, Kai; Amelon, Ryan E.; Du, Kaifang; Reinhardt, Joseph M.; Raghavan, Madhavan L.; Christensen, Gary E.

    Image registration plays an important role within pulmonary image analysis. The task of registration is to find the spatial mapping that brings two images into alignment. Registration algorithms designed for matching 4D lung scans or two 3D scans acquired at different inflation levels can catch the temporal changes in position and shape of the region of interest. Accurate registration is critical to post-analysis of lung mechanics and motion estimation. In this chapter, we discuss lung-specific adaptations of intensity-based registration methods for 3D/4D lung images and review approaches for assessing registration accuracy. Then we introduce methods for estimating tissue motion and studying lung mechanics. Finally, we discuss methods for assessing and quantifying specific volume change, specific ventilation, strain/ stretch information and lobar sliding.

  15. Geodesic Active Fields: A Geometric Framework for Image Registration

    OpenAIRE

    Zosso, Dominique

    2011-01-01

    Image registration is the concept of mapping homologous points in a pair of images. In other words, one is looking for an underlying deformation field that matches one image to a target image. The spectrum of applications of image registration is extremely large: It ranges from bio-medical imaging and computer vision, to remote sensing or geographic information systems, and even involves consumer electronics. Mathematically, image registration is an i...

  16. Vertebral surface registration using ridgelines/crestlines

    Science.gov (United States)

    Tan, Sovira; Yao, Jianhua; Yao, Lawrence; Summers, Ronald M.; Ward, Michael M.

    2008-03-01

    The Iterative Closest Point (ICP) algorithm is an efficient and popular technique for surface registration. It however suffers from the well-known problem of local minima that make the algorithm stop before it reaches the desired global solution. ICP can be improved by the use of landmarks or features. We recently developed a level set capable of evolving on the surface of an object represented by a triangular mesh. This level set permits the segmentation of portions of a surface based on curvature features. The boundary of a segmented portion forms a ridgeline/crestline. We show that the ridgelines/crestlines and corresponding enclosed surfaces extracted by the algorithm can substantially improve ICP registration. We compared the performance of an ICP algorithm in three setups: 1) ICP without landmarks. 2) ICP using ridgelines. 3) ICP using ridgelines and corresponding enclosed surfaces. Our material consists of vertebral body surfaces extracted for a study about the progression of Ankylosing Spondylitis. Same vertebrae scanned at intervals of one or two years were rigidly registered. Vertebral body rims and the end plate surfaces they enclose were used as landmarks. The performance measure was the mean error distance between the registered surfaces. From the one hundred registrations that we performed the average mean error was respectively 0.503mm, 0.335mm and 0.254mm for the three setups. Setup 3 almost halved the average error of setup 1. Moreover the error range is dramatically reduced from [0.0985, 2.19]mm to just [0.0865, 0.532]mm, making the algorithm very robust.

  17. Automatic registration of serial mammary gland sections

    Energy Technology Data Exchange (ETDEWEB)

    Arganda-Carreras, Ignacio; Fernandez-Gonzalez, Rodrigo; Ortiz-de-Solorzano, Carlos

    2004-04-13

    We present two new methods for automatic registration of microscope images of consecutive tissue sections. They represent two possibilities for the first step in the 3-D reconstruction of histological structures from serially sectioned tissue blocks. The goal is to accurately align the sections in order to place every relevant shape contained in each image in front of its corresponding shape in the following section before detecting the structures of interest and rendering them in 3D. This is accomplished by finding the best rigid body transformation (translation and rotation) of the image being registered by maximizing a matching function based on the image content correlation. The first method makes use of the entire image information, whereas the second one uses only the information located at specific sites, as determined by the segmentation of the most relevant tissue structures. To reduce computing time, we use a multiresolution pyramidal approach that reaches the best registration transformation in increasing resolution steps. In each step, a subsampled version of the images is used. Both methods rely on a binary image which is a thresholded version of the Sobel gradients of the image (first method) or a set of boundaries manually or automatically obtained that define important histological structures of the sections. Then distance-transform of the binary image is computed. A proximity function is then calculated between the distance image of the image being registered and that of the reference image. The transformation providing a maximum of the proximity function is then used as the starting point of the following step. This is iterated until the registration error lies below a minimum value.

  18. MULTI-FEATURE MUTUAL INFORMATION IMAGE REGISTRATION

    Directory of Open Access Journals (Sweden)

    Dejan Tomaževič

    2012-03-01

    Full Text Available Nowadays, information-theoretic similarity measures, especially the mutual information and its derivatives, are one of the most frequently used measures of global intensity feature correspondence in image registration. Because the traditional mutual information similarity measure ignores the dependency of intensity values of neighboring image elements, registration based on mutual information is not robust in cases of low global intensity correspondence. Robustness can be improved by adding spatial information in the form of local intensity changes to the global intensity correspondence. This paper presents a novel method, by which intensities, together with spatial information, i.e., relations between neighboring image elements in the form of intensity gradients, are included in information-theoretic similarity measures. In contrast to a number of heuristic methods that include additional features into the generic mutual information measure, the proposed method strictly follows information theory under certain assumptions on feature probability distribution. The novel approach solves the problem of efficient estimation of multifeature mutual information from sparse high-dimensional feature space. The proposed measure was tested on magnetic resonance (MR and computed tomography (CT images. In addition, the measure was tested on positron emission tomography (PET and MR images from the widely used Retrospective Image Registration Evaluation project image database. The results indicate that multi-feature mutual information, which combines image intensities and intensity gradients, is more robust than the standard single-feature intensity based mutual information, especially in cases of low global intensity correspondences, such as in PET/MR images or significant intensity inhomogeneity.

  19. Collaborative Error Registration Algorithm for Radar System

    Institute of Scientific and Technical Information of China (English)

    WU Ze-min; REN Shu-jie; LIU Xi

    2009-01-01

    Affected by common target selection, target motion estimation and time alignment, the radar system error registration algorithm is greatly limited in application. By using communication and time synchronization function of a data link network, a collaborative algorithm is proposed, which makes use of a virtual coordinates constructed by airplane to get high precision measurement source and realize effective estimation of the system error. This algorithm is based on Kalman filter and does not require high capacities in memory and calculation. Simulated results show that the algorithm has better convergence performance and estimation precision, no constrain on sampling period and accords with transfer characteristic of data link and tactical internet perfectly.

  20. Efficient Variational Approaches for Deformable Registration of Images

    Directory of Open Access Journals (Sweden)

    Mehmet Ali Akinlar

    2012-01-01

    Full Text Available Dirichlet, anisotropic, and Huber regularization terms are presented for efficient registration of deformable images. Image registration, an ill-posed optimization problem, is solved using a gradient-descent-based method and some fundamental theorems in calculus of variations. Euler-Lagrange equations with homogeneous Neumann boundary conditions are obtained. These equations are discretized by multigrid and finite difference numerical techniques. The method is applied to the registration of brain MR images of size 65×65. Computational results indicate that the presented method is quite fast and efficient in the registration of deformable medical images.