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Effects of various generations of iterative CT reconstruction algorithms on low-contrast detectability as a function of the effective abdominal diameter: A quantitative task-based phantom study

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PHYSICA MEDICA-EUROPEAN JOURNAL OF MEDICAL PHYSICS 2018年 48卷 111-118页

作者： Viry, Anais Aberle, Christoph Racine, Damien Knebel, Jean-Francois Schindera, Sebastian T. Schmidt, Sabine Becce, Fabio Verdun, Francis R. Lausanne Univ Hosp Inst Radiat Phys Rue Grand Pre 1 CH-1007 Lausanne Switzerland Univ Basel Univ Hosp Basel Dept Radiol Basel Switzerland Lausanne Univ Hosp Dept Radiol Lab Invest Neurophysiol LINE Lausanne Switzerland Lausanne Univ Hosp Dept Clin Neurosci Lausanne Switzerland Ctr Biomed Imaging CIBM Electroencephalog Brain Mapping Core Lausanne Switzerland Ctr Biomed Imaging CIBM Electroencephalog Brain Mapping Core Geneva Switzerland Kantonsspital Aarau Dept Radiol Aarau Switzerland Lausanne Univ Hosp Dept Diagnost & Intervent Radiol Lausanne Switzerland

Purpose: To investigate how various generations of iterative reconstruction (IR) algorithms impact low-contrast detectability (LCD) in abdominal computed tomography (CT) for different patient effective diameters, using a quantitative task-based approach. Methods: Investigations were performed using an anthropomorphic abdominal phantom with two optional additional rings to simulate varying patient effective diameters (25, 30, and 35 cm), and containing multiple spherical targets (5, 6, and 8 mm in diameter) with a 20-HU contrast difference. The phantom was scanned using routine abdominal protocols (CTDIvol, 5.9-16 mGy) on four CT systems from two manufacturers. Images were reconstructed using both filtered back-projection (FBP) and various IR algorithms: ASiR 50%, SAFIRE 3 (both statistical IRs), ASiR-V 50%, ADMIRE 3 (both partial model-based IRs), or Veo (full model-based IR). Section thickness/interval was 2/1 mm or 2.5/1.25 mm, except 0.625/0.625 mm for Veo. We assessed LCD using a channelized Hotelling observer with 10 dense differences of Gaussian channels, with the area under the receiver operating characteristic curve (AUC) as a figure of merit. Results: For the smallest phantom (25-cm diameter) and smallest lesion size (5-mm diameter), AUC for FBP and the various IR algorithms did not significantly differ for any of the tested CT systems. For the largest phantom (35-cm diameter), Veo yielded the highest AUC improvement (8.5%). Statistical and partial model-based IR algorithms did not significantly improve LCD. Conclusion: In abdominal CT, switching from FBP to IR algorithms offers limited possibilities for achieving significant dose reductions while ensuring a constant objective LCD.

关键词： Computed tomography iterative reconstruction algorithms Low-contrast detectability Mathematical model observers Task-based image quality assessment

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Essentials of Algebraic reconstruction in Cone-Beam Computed Tomography

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BULLETIN OF THE LEBEDEV PHYSICS INSTITUTE 2023年第10期50卷 438-444页

作者： Chernukha, A. E. Shestopalov, A. I. Adarova, A. I. Shershnev, R. V. Kizilova, Ya. V. Koryakin, S. N. Ivanov, S. A. Solovev, A. N. Russian Federat Branch Natl Med Res Radiol Ctr Tsyb Med Radiol Res Ctr A Tsyb MRRC Minist Hlth Obninsk 249031 Kaluga Region Russia Protom Ltd Protvino 142281 Moscow oblast Russia Russian Acad Sci Lebedev Phys Inst Phys Tech Ctr Protvino Moscow Oblast Russia Inst Nucl Power Engn Obninsk 249020 Kaluga Oblast Russia Peoples Friendship Univ Russia Moscow 117198 Russia

ART (algebraic reconstruction technique) in computed tomography (CT) and, in particular, the reconstruction under a limited number of cone-beam projections, along with conventional CT methods, allow an image quality sufficient for patient positioning, as well as reducing the dose payload and treatment toxicity and increasing local tumor control. In addition, such reconstructed images may serve as prognostic factors for patient selection. The proposed methods are overviewed for the bone structures imaging CT procedures for the further usage in planning, positioning and immobilization stages. The limited number of projection fields are chosen within circular scanning using 900 projections in the desired 90 degrees-360 degrees field of view angle. The dynamic range of image extension are presented, reconstruction isogonality degeneracies are discussed, as well as options of semi-convergence of low-noise solutions. The orthogonal images obtained with ART can be prospectively used in various radiotherapy techniques, with special attention to hypofractionated schemes. The algorithms were examined at the "Prometheus" proton beam facility and are beneficial in the therapeutic applications.

关键词： cone-beam computed tomography CBCT iterative reconstruction algorithms radiation safety

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The Actual Role of iterative reconstruction Algorithm Methods in Several Saudi Hospitals As A Tool For Radiation Dose Minimization of Ct Scan Examinations

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JOURNAL OF MULTIDISCIPLINARY HEALTHCARE 2022年 15卷 1747-1757页

作者： Alsleem, Haney Tajaldeen, Abdulrahman Almutairi, Abdulrahman Almohiy, Hussain Aldaais, Ebtisam Albattat, Rayan Alsleem, Mousa Abuelhia, Elfatih Kheiralla, Osama Abdalla Mabrouk Alqahtani, Ahmed Alghamdi, Salem Aljondi, Rowa Alharbi, Renad Imam Abdulrahman Bin Faisal Univ Dept Radiol Sci Dammam Saudi Arabia King Fahad Specialist Hosp Med Imaging Dept Dammam Saudi Arabia King Khalid Univ Radiol Sci Abha Saudi Arabia King Faisal Univ Coll Dent Alahsa Saudi Arabia King Saud Med City Radiol Dept Riyadh Saudi Arabia Univ Jeddah Dept Appl Radiol Technol Jeddah Saudi Arabia Specialized Med Complex Dept Radiol Jeddah Saudi Arabia

Background: iterative reconstruction algorithm (IR) techniques were developed to maintain a lower radiation dose for patients as much as possible while achieving the required image quality and medical benefits. The main purpose of the current research was to assess the level and usage extent of IR techniques in computed tomographic (CT) scan exams. Also, the obligation of practitioners in several hospitals in Saudi Arabia to implement IR in CT exams was *** and Methodology: The recent research was based on two studies: data collection and a survey study. Data on the CT scan examinations were retrospectively collected from CT scanners. The survey was conducted using a questionnaire to evaluate radio-graphers' and radiologists' perceptions about IR and their practices with IR techniques. The statistical analysis results were performed to measure the usage strength level of IR *** and Discussions: The IR strength level of 50% was selected for nearly 80% of different CT examinations and patients of different ages and weights. About 46% of the participants had not learned about IR methods during their college studies, and 54% had not received formal training in applying IR techniques. Only 32% of the participants had adequate experience with IR. Half of the participants were not involved in the updating process of the CT ***: The results indicate that the majority of radiographer and radiologist at four different hospitals in Saudi Arabia have no explicit or understandable knowledge of selecting IR strength levels during the CT examination of patients. There is a need for more training in IR applications for both radiologists and radiographers. Training sessions were suggested to support radiographers and radiologists to efficiently utilize IR techniques to optimize image quality. Further studies are required to adjust CT exam protocols effectively to utilize the IR technique.

关键词： computed tomography CT filter back projection FBP iterative reconstruction algorithms IR as low as reasonably achievable ALARA

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Continuous-to-Continuous Data Model vs. Discrete-to-Discrete Data Model for the Statistical iterative reconstruction Method 22nd

Continuous-to-Continuous Data Model vs. Discrete-to-Discrete...

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22nd Annual International Conference on Computational Science (ICCS)

作者： Cierniak, Robert Czestochowa Tech Univ Dept Intelligent Comp Syst Armii Krajowej 36 PL-42200 Czestochowa Poland

ISBN: (纸本)9783031087547;9783031087530

The article presents a comparison of two statistical approaches to the problem of image reconstruction from projections: the worldwide known concept based on a discrete-to-discrete data model and our original idea based on a continuous-to-continuous data model. Both reconstruction approaches are formulated taking into account the statistical properties of signals obtained by CT scanners. The main goal of this strategy is significantly improving the quality of the reconstructed images, so allowing a reduction in the x-ray dose absorbed by a patient during CT examinations. In the concept proposed by us, the reconstruction problem is formulated as a shift-invariant system. In consequence, that significantly improves the quality of the subsequently reconstructed images, and it allows to reduce the computational complexity compared to the reference method. The performed by us experiments have shown that our original reconstruction method outperforms the referential approach regarding the image quality obtained and the time of necessary calculations.

关键词： iterative reconstruction algorithms Computed tomography Statistical methods

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A stochastic alternative technique for Compton Maximum Likelihood Expectation-Maximization (MLEM) reconstruction

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COMPUTERS IN BIOLOGY AND MEDICINE 2023年 166卷 107502-107502页

作者： Tomazinaki, Mina-Ermioni Stiliaris, Efstathios Natl & Kapodistrian Univ Athens Dept Phys Athens Greece Inst Accelerating Syst & Applicat IASA Athens Greece

Even though iterative methods and particularly Maximum Likelihood Expectation-Maximization (MLEM) algorithms have been established in reconstruction with Compton data, their detailed design with respect to physical rules and processes dominate their plain implementation in the form of a system matrix. A new elementary but efficient alternative for the well-known system matrix with respect to Compton Camera image reconstruction is presented in this work. For each detected event there is a weighting factor inserted as an accumulated probability which carries all the necessary information. This probability which involves only the Compton scattering angle of the incident photon corresponds to a map that correlates all events within all possible source origins. Based on maximizing likelihood principles, the proposed model weights in a stochastic way the difference of the scatterer-to-source angle 00, as it is determined by the deposited energy on the absorber, and any other potential scattering angle 0,, specified by the position coordinates on the reconstruction matrix. Obtained image spatial resolution, angular distortions and response to focal length determination are a few of the studied cases for the algorithms' evaluation via simulations in GEANT4/GATE with a set of radioactive sources and phantoms with in-and out-of-plane arrangement.

关键词： Compton Camera Compton kinematics GEANT4/GATE Monte-Carlo simulation iterative reconstruction algorithms Log-likelihood Maximum Likelihood Expectation-Maximization (MLEM) List-Mode MLEM Dopamine Transporter scan

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Accelerated iterative image reconstruction for cone-beam computed tomography through Big Data frameworks

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FUTURE GENERATION COMPUTER SYSTEMS-THE INTERNATIONAL JOURNAL OF ESCIENCE 2020年 106卷 534-544页

作者： Serrano, Estefania Garcia-Blas, Javier Carretero, Jesus Desco, Manuel Abella, Monica Univ Carlos III Madrid Comp Architecture & Technol Grp Madrid Spain Inst Invest Sanitaria Gregorio Maranon Madrid Spain Univ Carlos III Madrid Dept Bioingn & Ingn Aeroespacial Madrid Spain Ctr Nacl Invest Cardiovasculares Carlos III Madrid 28911 Spain Ctr Invest Biomed Red Salud Mental CIBERSAM Madrid Spain

One of the latest trends in Computed Tomography (CT) is the reduction of the radiation dose delivered to patients through the decrease of the amount of acquired data. This reduction results in artifacts in the final images if conventional reconstruction methods are used, making it advisable to employ iterative algorithms to enhance image quality. Most approaches are built around two main operators, backprojection and projection, which are computationally expensive. In this work, we present an implementation of those operators for iterative reconstruction methods exploiting the Big Data paradigm. We define an architecture based on Apache Spark that supports both Graphical Processing Units (GPU) and CPU-based architectures. The aforementioned are parallelized using a partitioning scheme based on the division of the volume and irregular data structures in order to reduce the cost of communication and computation of the final images. Our solution accelerates the execution of the two most computational expensive components with Apache Spark, improving the programming experience of new iterative reconstruction algorithms and the maintainability of the source code increasing the level of abstraction for non-experienced high performance programmers. Through an experimental evaluation, we show that we can obtain results up to 10x faster for projection and 21x faster for backprojection when using a GPU-based cluster compared to a traditional multi-core version. Although a linear speed up was not reached, the proposed approach can be a good alternative for porting previous medical image reconstruction applications already implemented in C/C++ or even with CUDA or OpenCL programming models. Our solution enables the automatic detection of the GPU devices and execution on CPU and GPU tasks at the same time under the same system, using all the available resources. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Apache Spark GPU Medical image processing Computed tomography iterative reconstruction algorithms

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High-quality X-ray computed tomography reconstruction using projected and interpolated images

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IET IMAGE PROCESSING 2019年第7期13卷 1074-1080页

作者： Bappy, D. M. Jeon, Insu Chonnam Natl Univ Sch Mech Engn 77 Yongbong Ro Gwangju 61186 South Korea

Recent advances in computation power have allowed computed tomography (CT) to utilise iterative reconstruction (IR) algorithms. The IR technique can handle noisy data and reconstructs optimal CT images from limited projected images. As of cyclic image processing, IR improves the quality of CT images. This approach requires a minimum number of projections to reconstruct an image;however, decreasing the number of projections to 90 can create artefacts and degrade reconstruction quality. To overcome this limitation, the optical flow technique can compute flow vectors between two consecutive projections to generate projected images between frames. Here, optical flow-based frame interpolation combined with the ordered subset-modified iterative technique is proposed to reduce computation time, lower the number of projections, and increase reconstruction quality of CT images. The proposed technique can be used to reconstruct a CT image from 90 projections at 4 degree intervals between projection sequences. This approach produces a much better quality reconstruction compared to that produced by an analytical algorithm, which uses 360 projections. The inclusion of an ordered subset reconstructs CT images quickly by accelerating streaming architecture.

关键词： image reconstruction iterative methods interpolation computerised tomography medical image processing image sequences quality reconstruction projection sequences increase reconstruction quality computation time ordered subset-modified iterative technique optical flow-based frame interpolation consecutive projections optical flow technique degrade reconstruction quality CT image cyclic image processing projected images noisy data IR technique iterative reconstruction algorithms computation power X-ray computed tomography reconstruction high-quality

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A CONVOLUTIONAL FRAMEWORK FOR FORWARD AND BACK-PROJECTION IN FAN-BEAM GEOMETRY 16

A CONVOLUTIONAL FRAMEWORK FOR FORWARD AND BACK-PROJECTION IN...

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16th IEEE International Symposium on Biomedical Imaging (ISBI)

作者： Zhang, Kai Entezari, Alireza Univ Florida CISE Dept Gainesville FL 32611 USA

ISBN: (纸本)9781538636411

We present a convolutional spline framework for highly efficient and accurate computation of forward model for image reconstruction in fan-beam geometry in X-ray computed tomography. The efficiency of computations makes this framework suitable for large-scale optimization algorithms with on the-fly, memory-less, computations of the forward and hack projection. Our experiments demonstrate the improvements in accuracy as well as efficiency of our model, specifically for first-order box splines (i.e., pixel-basis) compared to recently developed methods for this purpose, namely Look-up Table based Ray Integration (LTRI) and Separable Footprints (SF) in 2-D.

关键词： computed tomography iterative reconstruction algorithms

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BOX SPLINE PROJECTION IN NON-PARALLEL GEOMETRY 16

BOX SPLINE PROJECTION IN NON-PARALLEL GEOMETRY

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16th IEEE International Symposium on Biomedical Imaging (ISBI)

作者： Zhang, Kai Entezari, Alireza Univ Florida CISE Dept Gainesville FL 32611 USA

ISBN: (纸本)9781538636411

The pixel- and voxel-basis are common choices for image discretization in the context of computed tomography (CT). They can also be viewed as first-order box splines a class of functions with closed-form X-ray and Radon transforms that can be computed efficiently. In this paper we derive a method for exact projection of box splines in a non-parallel geometry that can be used in fan-beam and cone-beam tomographic image reconstruction algorithms. We also provide efficient computational procedures for evaluation of the basis function in the projection domain.

关键词： computed tomography iterative reconstruction algorithms

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iterative metal artifact reduction in aortic CTA after Onyx®-embolization

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EUROPEAN JOURNAL OF RADIOLOGY OPEN 2020年 7卷 100255-100255页

作者： Lehti, Leena Soderberg, Marcus Mellander, Helena Wasselius, Johan Lund Univ Dept Clin Sci Lund Sweden Skane Univ Hosp Vasc Ctr Malmo Sweden Lund Univ Dept Translat Med Med Radiat Phys Malmo Sweden Skane Univ Hosp Dept Hematol Oncol & Radiat Phys Radiat Phys Malmo Sweden Skane Univ Hosp Dept Neuroradiol Lund Sweden

Purpose: Onyx (R) embolization causes severe artifacts on subsequent CT-examinations, thereby seriously limiting the diagnostic quality. The purpose of this work was to compare the diagnostic quality of the tailored metal artifact reducing algorithms iMAR to standard reconstructions of CTA in patients treated with Onyx (R) embolization. Method: Twelve consecutive patients examined with Dual Energy CTA after Onyx (R) embolization were included. One standard image dataset without iMAR, and eight image datasets with different iMAR algorithms were reconstructed. Mean attenuation and noise were measured in the aorta or iliac arteries close to the Onyx (R) gluecast and compared to the reference level in the diaphragmatic aorta. Mean attenuation and noise were also measured in the psoas muscle close to the Onyx (R)-glue and compared to the reference level in the psoas muscle at the level of the diaphragm. Subjective image quality and severity of artifacts was assessed by two experienced interventional radiologists blinded to reconstruction details. Results: All iMAR reconstructions had less distortion of the attenuation than the standard reconstructions and were also rated significantly better than the standard reconstructions by both interventional radiologists. Conclusion: The iMAR algorithms can significantly reduce metal artifacts and improve the diagnostic quality in CTA in patients treated with Onyx (R) embolization, in many cases restoring non-diagnostic examinations to acceptable diagnostic quality.

关键词： Computed tomography Image quality iterative reconstruction algorithms Onyx (R) embolization Metal artifact reduction

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