By means of numerical simulations, it is verified that the algorithm developed ensured high quality of reconstruction. In this paper, we propose an endtoend limited angle tomography. Image reconstruction from such limited angle data suffers from artifacts because of missing data. We present a method for obtaining accurate image reconstruction from highly sparse data in diffraction tomography dt. Existing iterative reconstruction algorithms could not reconstruct highquality images, leading to severe artifacts nearby edges. Reconstructions in limited angle xray tomography mediatum. The developed limited angle tomography technique was demonstrated to be able to detect practically significant manufacturing defects voids and structural damage. Deep learning based image reconstruction algorithm for limited. Consequently, the use of the fbp algorithm is theoretically not justified in limited angle tomography. In application of tomography imaging, limited angle. Tomosynthesis, also digital tomosynthesis dts, is a method for performing highresolution limited angle tomography at radiation dose levels comparable with projectional radiography.
Projection data replenishment algorithm for limited angle. Characterization and reduction of artifacts in limited. A low radiation dose and high inplane resolution make lat an attractive alternative to computed tomography. The first category of algorithms are to restore missing data based on. Restoration of missing data in limited angle tomography based on. A reconstruction algorithm, based on a hybrid xray excitationdiffuse optical emission model, was tested in a numerical and experimental phantom that had dimensions similar to the human. In this article, we develop a model based iterative reconstruction mbir algorithm for haadfstem tomography. In this paper, we improve a statistical iterative algorithm based on the. Although our algorithm is proposed for the limited angle tct, since the sart method and deep learning technique will not be influenced by the geometrical structure of the scanning mode, our algorithm can be extended to the generic limited angle tomography, such as carm conebeam ct.
Photoninefficient but simple algorithms coded aperture imaging. Classical reconstruction methods, such as the conventional filtered backprojection fbp algorithm and the algebraic reconstruction method arm 47, have well. The algorithm is based on calculating artificial projections in those directions where projection data are unavailable. In this paper, we present comparative studies on exposure conditions in dbt, including narrow and wide angle scan using an invariant tube voltage of xray source, and wide angle scan with the voltage modulation technique.
An iterative algorithm for computed tomography image reconstruction from limitedangle projections. A new scale space total variation algorithm for limited angle tomography yixing huang, oliver taubmannz, xiaolin huang, viktor haasex, guenter lauritschy and andreas maierz pattern recognition lab, friedrichalexanderuniversity erlangennuremberg, erlangen, germany. Limited angle ct reconstruction is a very challenging illposed issue and of great interest in several clinical applications, such as digital breast tomosynthesis 1, dental tomography 2, short exposure time 3, etc. Deep learning based image reconstruction algorithm for. Since haadfstem tomography is a limited angle tomography modality with low signal to noise ratio, these methods can result in signi. Pdf backprojection filtering method for limited angle. Deep learning computed tomography pattern recognition lab.
Improving reconstructed image quality in a limitedangle positron. Various existing algorithms are available to solve the illposed regression problem by different solvers with different regularization terms louis and tornig and natterer solve it with the svd. An algorithm specifically designed for limited angle tomography. With this code we will be able to model any type of spill located at in any type of background material. In order to reduce blur artifacts originated from the outofplanes and control highfrequency noise, we employed two. Tests of the algorithm on two highquality data sets provided by perceptics, inc. For limited angle tomography, algorithms of adaptive steepest descent.
Iterative image reconstruction for limitedangle ct using. Introduction as a nondestructive imaging technology, computed tomography ct has been widely. An iterative algorithm for computed tomography image reconstruction from limited angle projections. Another well known approach to limited angle reconstruction are regularized iterative algorithms. Limited angle computed tomography was studied in a project to develop algorithms for a limited angle scanner. Evaluation of a limited angle scanned electron beam xray. It is caused by missing data over a certain angle interval, which make an inverse radon transform impossible. The limited angle problem is a wellknown problem in computed tomography. Limited angle ct reconstruction is an illposed inverse problem 3.
To better preserve the edges and suppress the artifacts to limited angle ct image reconstruction, we developed an alternating iterative reconstruction algorithm for limited angle ct based on. Exterior and limitedangle tomography in nondestructive. Limitedangle optical computed tomography algorithms. A practical need exists for reconstruction from fewview and limited angle data, as this can greatly reduce required scan times in dt. In this paper, we will focus on the severely illposed inverse problem of limited angle computed tomography, in which entire boundary sections are not captured in the measurements. By extending our prior work, here we propose a novel multiscale waveletdomain residual learning network for limited angle ct reconstruction.
Total variation iterative constraint algorithm for limited. Next, this dissertation aims to advance speed of sound, attenuation, and photoacoustic image reconstruction algorithms for the limited angle tomography approach. Pdf computed tomography ct is commonly used in clinical. Pdf deep learning based image reconstruction algorithm. Iucr limited angle tomography for transmission xray. Image prediction for limited angle tomography via deep learning with convolutional neural network hanming zhang 1, liang li2,3, 1kai qiao 1, linyuan wang, bin yan1, lei li, guoen hu 1 national digital switching system engineering and technological research center, zhengzhou, 450002, peoples republic of china 2 department ofengineering physics, tsinghua university, beijing, 84. The otherwise attractive convolutionbackprojection algorithm is not suited for ct image reconstruction from measurements comprising an incomplete set of projection data.
It is applicable to limited angle tomography as well since typical imaged objects in computed tomography have a limited spatial extent, which means that the fourier transforms of the objects can be considered band limited signals. Algorithms have been developed by researchers 6, 14, 17, 30. A deep learning architecture for limitedangle computed. Pet is accurate image reconstruction algorithms which can image the object of interest faithfully. Image prediction for limitedangle tomography via deep. However, ct images reconstructed from limited angle acquisitions suffer from severe artifacts due to incomplete sinogram data.
Improved backpropagation algorithms by exploiting data. It has been studied for a variety of clinical applications, including vascular imaging, dental imaging, orthopedic imaging, mammographic imaging, musculoskeletal imaging, and chest imaging. In daily routine this problem can arise for example in tomosynthesis, carm ct or dental ct. Those characterizations will precisely explain where and why artifacts are created by these algorithms. The principle depends on the geometry of the data set, and it applies.
We will use fdtd to generate the signals the radar collects at a spill site. Scalespace anisotropic total variation for limited angle. The optimal scan acquisition procedure paired with the improved reconstruction algorithm facilitated higher inplane and depth resolution compared to the clinical application. Optimal selection of initial image would influence the iterative reconstruction performance but has not been studied deeply yet. Optical computed tomography oct is often used for measuring thermophysical parameters. This thesis investigates the limited angle tomography problem where axial. Ct, reconstructions from sparse views or limited angle tomography are. Optimization for limited angle tomography in medical image processing xiaoqiang lua, yi suna, yuan yuanb,n a school of electronic and information engineering, dalian university of technology, china b center for optical imagery analysis and learning optimal, state key laboratory of transient optics and photonics, xian institute of optics and precision mechanics. Artifacts and visible singularities in limited data xray. A deep learning architecture for limitedangle computed tomography reconstruction kerstin hammernik1, tobias wur 2, thomas pock1. Many specialized iterative algorithms exist which clearly improve the image quality 1. Limited angle tomography lat is an xray imaging technique for generating a stack of crosssectional images based on a limited number of twodimensional projections. Accurate computed tomography ct reconstruction from incomplete projections is an important research topic.
This misplacement, however, could be minimized easily by routinely calibrating transducer positions. In the following section we outline the basic theory of diffraction tomography. Both the art algorithm and an orthogonal function algorithm were investigated. Iterative reconstruction algorithms can incorporate prior. A new scale space total variation algorithm for limited. Limited angle tomography uct digital image processing. Accurate image reconstruction from fewview and limited. The resulting algorithm is implemented numerically in two spatial dimensions and tested on simulated data. Improved backpropagation algorithms by exploiting data redundancy in limited angle di.
Indeed, although in our work we limit the number of line projections, but do not limit the angles, the fundamental understanding of the relationship between a functions edge singularities and its radon representation, as explained in 10, is at the core of our algorithm see figure 3. Pdf as a lowend computed tomography ct system, translational ct tct is in urgent demand in developing countries. Limited angle xray luminescence tomography has been developed as a means to image molecular deeper than is available with fluorescence molecular tomography. Based on these characterizations, we will explain how to mitigate those. Cardiac xray computed tomography ct has been limited due to scanning times which are considerably longer 1 s than required to resolve the beating heart 0. A method is presented for producing model limited angle artifact in phantom images. Abstractthe papoulisgerchberg pg algorithm is widely used for extrapolation of band limited signals. In particular, the network is designed in a directional wavelet transform domain to exploit the directional property of the limited angle artifacts. Wang 9 proposed a limitedangle ct image reconstruction algorithm based on the wavelet frame, and the reconstructed images show that it. Unsupervised learnable sinogram inpainting network sin. We describe a backprojection filtering method for limited angle tomography. Restoration of missing data in limited angle tomography.
In the course of this thesis, various algorithms are proposed to deal with data insufficiency in limited angle tomography. We will develop a hybrid reconstruction framework that fuses model. Pdf an improved statistical iterative algorithm for sparseview and. Scalespace anisotropic total variation for limited angle tomography yixing huang, oliver taubmann, xiaolin huang, viktor haase, guenter lauritsch, and andreas maier abstractthis paper addresses streak reduction in limited angle tomography. An iterative algorithm for computed tomography image reconstruction from limited angle projections yuli sun, jinxu tao, conggui liu department of electronic engineering and information science, university of science and technology of china, hefei 230027, peoples republic of china abstract. Limited angle ultrasound tomography of the compressed breast. Optimization for limited angle tomography in medical image. The illposedness of the limited angle tomography problem has been well investigated 1, 2. Standard tomographic algorithms applied to optical limited angle tomography result in the reconstructions that have highly anisotropic resolution and thus special algorithms are developed. Multiscale wavelet domain residual learning for limited. A new approach to limited angle tomography using the. One of the data sets is limited angle exterior data det with a range of 5. A deeplearning method for limited angle tomography in synchrotron radiation transmission xray microscopies and a demonstration of its application in 3d visualization of a chlorella cell.
Papoulisgerchberg algorithms for limited angle tomography. Classical incomplete data problems have been studied from the beginning of tomography, including limited angle tomography, where the data can be collected only from certain view angles 24,30. Characterization and reduction of artifacts in limited angle tomography 3 characterizations of the artifacts in limited angle fbp and reconstructions. Xdisystem multispectral source transmission detector. Sparse sampling and limited angle sampling are two effective ways to reduce the xray. Limited view tomography ct with limited angle data and few views irr algorithm iterative reconstructionreprojection irr. In the sparse angle tomography cases we used only 10. The artifact produced by the different methods was very similar. An iterative algorithm for computed tomography image.
State of the art approaches utilize the total variation tv minimization technique. A new iterative algorithm of tomographic reconstruction of objects on the basis of projection data available in a limited range of angles only is proposed. Limitedangle computed tomography suffers from missing data in the. A limited angle lambda tomography algorithm was given in 12. In a limited angle ct scan, the projection data can be obtained in less than 180 angular range, and the data insuf. Artifact reduction using the unet in limited angle tomography is such an example application.
Multiple limitedangles computed tomography reconstruction. As the projection data are highly incomplete, standard tomographic reconstruction algorithms, such as the wellknown fbp algorithm, will not afford a reliable. One group of deep learning reconstruction algorithms apply postprocessing neural networks to achieve imagetoimage reconstruction, where input images are reconstructed by conventional reconstruction methods. However, in the limited angle case the algorithm converges to a solution with typical limited angle artefacts. Filters are investigated for reducing the artifact, and it. Artifacts and visible singularities in limited data xray tomography eric todd quinto received.
In this thesis, we consider both sparse and limited angle tomography situations. A related algorithm has been developed by the author and tested on electron microscope data from the karolinska institute and sidec technologies unpublished. Unfortunately, viewing access in many tomographic experiments, such as in plasma physics, is extremely limited, which leads to a highly undetermined inversion problem. Captures more photons, complex inverse problem limited angle tomography. In the article iii, a new sinogram estimation algorithm called sinogram inter polation.
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