Evaluation of heavily calcified vessels with coronary ct angiography. Deep back projection for sparseview ct reconstruction. The volume ct dose index was significantly reduced in studies reconstructed with iterative model reconstruction compared with filtered backprojection, mean, 24. Lambertbeers law and the radon transform 2 2 reconstruction.
Filtered back projection vs adaptive statistical iterative. Tomographic reconstruction by filtered backprojection. Tvminimization by gradient descent, softthreshold filtering. Back projection is a way of recording how well the pixels of a given image fit the distribution of pixels in a histogram model. Iterative image reconstruction techniques resulted in ctbased cardiovascular risk categorization that is similar to that obtained with traditional filtered back projection reconstruction, although risk reclassification occurred in a small subset software library which was the result of a european union funded collaboration between 6 different partners. The basics for understanding what is iterative reconstruction. Involves filtered back projection, resulting in a digital matrix, which can be postprocessed for additional image analysis. Recent advances in ct technology and increased computational power have permitted the use of iterative reconstruction algorithms for ct image reconstruction. Iterative image reconstruction techniques for ct coronary. On the other hand, adequate image quality of fbp can be reached with lower dose using adaptive statistical iterative reconstruction asir by equalizing. You can see what any given projection looks like in the simulator above. In recent years, iterative ct reconstruction method is drawing attention as a new ct reconstruction against backprojection ct reconstruction method. Sign up matlab simulation for computed tomography image reconstruction using filtered back projection. Ct reconstruction package file exchange matlab central.
Image quality analysis the reconstructed cta images were transferred to workstations with a commercial cardiac ct software package for image. To compare organ specific radiation dose and image quality in kidney stone patients scanned with standard ct reconstructed with filtered back projection fbpct to those scanned with low dose ct reconstructed with iterative techniques irct. Implementation of iterative reconstruction offers the ability to minimize radiation exposure while preserving and, in some cases, improving image quality. Use results to constrain earthquake dynamics coherence between data and synthetics finiteslip inversions backfigure from chen ji projection. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Iterative reconstruction 101 imaging technology news.
Castor is an opensource multiplatform project for 4d emission pet and spect and transmission ct tomographic reconstruction. Kernel image reconstruction for ct radiology reference. Spiral acquisition and reconstruction with a digital flatpanel detector. The reconstruction algorithms used was the back projection bp and filtered back projection. In order to understand ct reconstruction, we first need to understand how the computed tomography scanner works. The algorithm is computationally intensive due to the on4 back projection step.
Illustration of recovering an object from its xray tomography data also known as sinogram. Another concept that is useful to use when considering ct reconstruction is the sinogram, which is simply the 2d array of data containing the. Fbp is computationally efficient but produces lower quality reconstructions than more sophisticated iterative methods, particularly when the number of views is lower than the number required by the nyquist rate. For the first time, a reconstruction technique based on filtered backprojection fbp using curved 3d backprojection lines is applied to 2d coherent. Reconstruct a complete 3d ct model that includes time and motion, creating a truly dynamic volumetric dataset. Chest computed tomography using iterative reconstruction vs filtered back projection. Computed tomography the evolution of image reconstruction for ctfrom filtered back projection to artificial intelligence martin j. They reconstructed raw ct data using filtered back projection and 3 levels of iterative reconstruction. Reconstruction program by matlab based on gui matlab graphical user interface in this program load the initial data in. Reconstruction of image from simple back projection file. Over a oneyear study period, adult kidney stone patients were retrospectively netted to capture the. For back projection, you calculate the histogram model of a feature and then use it to find this feature in an image. Approximately 4500 images per sample were reconstructed from xray projections using the backprojection reconstruction algorithm in nrecon software skyscan, v. Image reconstruction for ct scanner by using filtered back.
Since then, this technique has caused a true hype in the. Projection, backprojection and core iterative reconstruction routines are highly optimised. The kernel affects the appearance of image structures by sharpening the image. Ct image reconstruction tomoshop new generation ct. Computationally intensive tasks are gpu accelarated, achieving unprecedented performance. It is being replaced, however, by iterative reconstruction ir, which is becoming widely used to decrease the radiation dose in ct. You may receive emails, depending on your notification preferences. Ctimage processing and reconstruction flashcards quizlet.
The reconstruction is based on the classical filtered backprojection technique. The evolution of image reconstruction for ctfrom filtered. Backprojection onto reconstruction plane for example, after only three projections, the lines would intersect to yield a. Download tirius tomographic image reconstruction for free. By using iterative reconstruction algorithms in ct the image noise can be reduced comparing to filtered back projection fbp if the same dose is applicated. Hounsfield unit hu and tissue mineral density calibration procedures were performed in ctan software ct analyzer, v. Many studies have shown that substantial dose savings can be achieved in ct when ir is used 2.
Filtered backprojection reconstruction technique for. Analytic reconstruction filtered backprojection, iterative reconstruction sart, sirt, ossart image filtering used as regularization steps within the iterative reconstruction process. The infamous shepplogan phantom reconstructed from tomographic data sinogram using the classical filtered backprojection algorithm. Emphysema quantification using ultralowdose ct with. Comparison of iterative and filtered back projection image reconstruction. The most common algorithm used is the feldkamp, davis, and kress back projection algorithm. Input images in either raw, pfm, or hnd format are read, filtered, and backprojected into a userdefined volume geometry. With fbp, ct slices are reconstructed from projection data sinograms by applying a highpass filter followed by a backward projection step fig. Image quality of lowdose ct examinations in 80 patients. Set of functions performing ct reconstruction tasks like a radon transformation, a simple backprojection, a filtered backprojection using a convolution in the spatial domain, a filtered backprojection using a 2d fourier transformation, and a filtered back projection using the central slice theorem.
Processing large ct data files on gpus has been shown to be effective. Filtered back projection fbp is a classical method for image reconstruction from sinogram ct data. However, in order to evaluate iterative reconstruction software. Iterative reconstruction equal to filtered back projection. Currently, ct scans for the measurement of nodule size and growth, at baseline and on followup, use the conventional filtered back projection fbp algorithm for image reconstruction. This process corrects the image by reducing blurring 1. With the fast progress in ct technology, fbpbased algorithms got improved and extended to keep up with hardware progress, such as feldkamp et als 1984 solution for reconstruction of data.
Radiation exposure from multidetector computed tomography ct has become a pressing public health concern in both lay and medical publications. Alexander katsevich, made a revolutionary breakthrough in ct imaging by developing the first fast and exact 3d image. It utilizes simultaneous equations of ray sums taken at differing angles of a sine wave to compute the. Comparison of image quality from filtered back projection. Filtering is used to minimize streaks on the image that result from back projection smooth imagereduce artifacts. The kernel, also known as a convolution algorithm, refers to the process used to modify the frequency contents of projection data prior to back projection during image reconstruction in a ct scanner 1. Cobra is exxims implementation of 3d ct reconstruction using the filtered backprojection algorithm feldkamp or exxims proprietary algorithm samara, extended view technology. Since the early 1970s, filtered back projection has been used for ct image reconstruction. Fully 3dimensional osem spect and pet iterative reconstructions can be obtained within a. Filtered back projection fbp algorithms are suited for applications where an image needs to be reconstructed accurately and in near realtime. The advantage of iterative ct reconstruction method is reconstruction results with high image quality can be obtained even with few projected imagesraw data.
Furthermore, this article presents a comprehensive background study on image reconstruction using filtered back projection fbp approaches to develop the ct scanner software. Ring reduction compensates for the irregular response of the detector pixels during a ct scan. It was, up until recently the primary method in crosssectional imaging reconstruction. The purpose of this study was to compare the image noisereducing abilities of iterative model reconstruction imr with those of traditional filtered back projection fbp and statistical iterative reconstruction ir in abdominal computed tomography ct images. Filtered back projection is an analytic reconstruction algorithm designed to overcome the limitations of conventional back projection.
In fact, it took until 2009 for the first iterative reconstruction algorithms to come commercially available and replace conventional filtered back projection. Evaluation of heavily calcified vessels with coronary ct. Start studying ctimage processing and reconstruction. The first ct scanners in the early 1970s already used iterative reconstruction algorithms. This platform is a scalable software providing both basic image reconstruction features for standard users and advanced tools for specialists in the reconstruction field, to develop, incorporate and assess their own methods in image. Pgqquality management slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. A conebeam ct reconstruction application is provided which implements filtered backprojection using the feldkamp, davis, and kress fdk algorithm.
548 849 871 1269 305 721 1081 1622 201 42 1077 774 375 60 616 1530 984 909 876 1530 757 1211 106 514 1378 199 725 786 20 228