Download or read book Respiratory Motion Compensation in Emission Tomography written by Mauricio Antonio Reyes Aguirre and published by . This book was released on 2005 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis work deals with the problem of respiratory motion correction in emission tomography. It has been proven that respiratory motion renders blurred reconstructed images, affecting lesions detection, diagnosis, treatment, etc. The proposed approach was designed to work without any external tracking devices. It presents a retrospective scheme of motion correction based on a motion model plugged to the image reconstruction step. The model takes into account displacements and elastic deformations of emission elements (voxels), which allows to consider the non-rigid deformations produced in the thorax during respiration. Furthermore, the chosen voxel modeling improves computations, outperforming classical methods of voxel/detector-tube. Two estimation models were investigated and developed. A first simplified model consists on adapting a known respiratory motion model, obtained from a single subject, to the patient anatomy. The initial known model describes by means of a displacement vector field, the lungs deformations produced between extremal respiratory states. This displacement vector field is further adapted by means of an affine transformation to the patient's anatomy, yielding a displacement vector field that matches the thoracic cavity of the patient . The second method deals with the possible lack of robustness caused by the fact of using a single subject when constructing the known displacement vector field of the simplified method. Incorporation of subject variability into a statistical respiratory motion model was developed. The whole methodology was developed under a 3D framework and tested against simulated and real data.

Download or read book Lesion Quantification in Respiratory Motion Compensated Positron Emission Tomography written by Nicole Christine Detorie and published by . This book was released on 2009 with total page 810 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ultra low dose CT based Attenuation Correction for Respiratory Motion Compensation in PET CT Imaging written by Tzu-Cheng Lee and published by . This book was released on 2017 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: Positron emission tomography (PET) is a commonly used imaging tool in the management of patients with lung cancer and is of considerable interest in quantitative imaging of the thorax. Mismatch of PET data with computed tomography (CT) attenuation correction (CTAC) due to respiratory motion is a known source of errors in PET imaging. In theory, this can be corrected by matching individual PET and CT phases which have been generated by respiratory-correlated PET and CT. However, due to the high variability of patient breathing patterns and the nature of the scanning time differences between PET and CT, current respiratory-gated CTAC protocols for the irregular breather may cause additional bias in the PET image values. A ten-fold extension of the CT scanning time duration helps reduce PET imaging bias, but leads to the higher radiation dose to the patient. Lowering the CT source flux level to reduce dose, however, leads to increased noise and bias. Here we test the possibility of using model based iterative reconstruction algorithms (MBIRs) for generating the sparse-view, ultra-low-dose (i.e. an order lower than current low-dose protocols) CTAC images for both phantom and patient PET data. We also propose a new variance estimation model, which considers statistical changes caused by the non-positivity correction process, for the MBIR algorithms. The model based iterative CT reconstruction approach does generate more accurate CTAC map compared to current approaches. However, since iterative reconstruction algorithms typically assume a normal distribution of the attenuation data, we tested if the assumption is still valid in the ultra-low-dose regime. The simulation and empirical ultra-low-dose CT studies showed a skewed post-log likelihood distribution in certain ranges. The information delineates the estimation limits of model based iterative reconstruction approach on the ultra-low-dose CT imaging, and potentially helps guide scanning protocols customized for a lowest-reasonable radiation dose.

Download or read book Motion Correction in Thoracic Positron Emission Tomography written by Fabian Gigengack and published by Springer. This book was released on 2014-09-10 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: Respiratory and cardiac motion leads to image degradation in Positron Emission Tomography (PET), which impairs quantification. In this book, the authors present approaches to motion estimation and motion correction in thoracic PET. The approaches for motion estimation are based on dual gating and mass-preserving image registration (VAMPIRE) and mass-preserving optical flow (MPOF). With mass-preservation, image intensity modulations caused by highly non-rigid cardiac motion are accounted for. Within the image registration framework different data terms, different variants of regularization and parametric and non-parametric motion models are examined. Within the optical flow framework, different data terms and further non-quadratic penalization are also discussed. The approaches for motion correction particularly focus on pipelines in dual gated PET. A quantitative evaluation of the proposed approaches is performed on software phantom data with accompanied ground-truth motion information. Further, clinical applicability is shown on patient data. The book concludes with an outlook of recent developments and potential future advances in the field of PET motion correction.

Download or read book Respiratory Motion Correction for Positron Emission Tomography written by Nikolaos Dikaios and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Respiratory Motion Correction on 3D Positron Emission Tomography Images written by Mohammad Dawood and published by . This book was released on 2008 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Respiratory Motion Correction in Positron Emission Tomography written by Wenjia Bai and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book 4D Modeling and Estimation of Respiratory Motion for Radiation Therapy written by Jan Ehrhardt and published by Springer Science & Business Media. This book was released on 2013-05-30 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: Respiratory motion causes an important uncertainty in radiotherapy planning of the thorax and upper abdomen. The main objective of radiation therapy is to eradicate or shrink tumor cells without damaging the surrounding tissue by delivering a high radiation dose to the tumor region and a dose as low as possible to healthy organ tissues. Meeting this demand remains a challenge especially in case of lung tumors due to breathing-induced tumor and organ motion where motion amplitudes can measure up to several centimeters. Therefore, modeling of respiratory motion has become increasingly important in radiation therapy. With 4D imaging techniques spatiotemporal image sequences can be acquired to investigate dynamic processes in the patient’s body. Furthermore, image registration enables the estimation of the breathing-induced motion and the description of the temporal change in position and shape of the structures of interest by establishing the correspondence between images acquired at different phases of the breathing cycle. In radiation therapy these motion estimations are used to define accurate treatment margins, e.g. to calculate dose distributions and to develop prediction models for gated or robotic radiotherapy. In this book, the increasing role of image registration and motion estimation algorithms for the interpretation of complex 4D medical image sequences is illustrated. Different 4D CT image acquisition techniques and conceptually different motion estimation algorithms are presented. The clinical relevance is demonstrated by means of example applications which are related to the radiation therapy of thoracic and abdominal tumors. The state of the art and perspectives are shown by an insight into the current field of research. The book is addressed to biomedical engineers, medical physicists, researchers and physicians working in the fields of medical image analysis, radiology and radiation therapy.

Download or read book Correction Techniques in Emission Tomography written by Mohammad Dawood and published by CRC Press. This book was released on 2012-04-27 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by an interdisciplinary team of medical doctors, computer scientists, physicists, engineers, and mathematicians, Correction Techniques in Emission Tomography presents various correction methods used in emission tomography to generate and enhance images. It discusses the techniques from a computer science, mathematics, and physics viewpoint. The book gives a comprehensive overview of correction techniques at different levels of the data processing workflow. It covers nuclear medicine imaging, hybrid emission tomography (PET-CT, SPECT-CT, PET-MRI, PET-ultrasound), and optical imaging (fluorescence molecular tomography). It illustrates basic principles as well as recent advances, such as model-based iterative algorithms and 4D methods. An important aspect of the book is on new and sophisticated motion correction techniques in PET imaging. These techniques enable high-resolution, high-quality images, leading to better imaging analysis and image-based diagnostics. Reflecting state-of-the-art research, this volume explores the range of problems that occur in emission tomography. It looks at how the resulting images are affected and presents practical compensation methods to overcome the problems and improve the images.

Download or read book Comparison of Protocols with Respiratory gated 4D Motion Compensation in PET CT Open source Package for Quantification of Phantom Image Quality written by Andrea Martinez-Movilla and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Background Patient's breathing affects the quality of chest images acquired with positron emission tomography/computed tomography (PET/CT) studies. Movement correction is required to optimize PET quantification in clinical settings. We present a reproducible methodology to compare the impact of different movement compensation protocols on PET image quality. Static phantom images were set as reference values, and recovery coefficients (RCs) were calculated from motion compensated images for the phantoms in respiratory movement. Image quality was evaluated in terms of: (1) volume accuracy (VA) with the NEMA phantom; (2) concentration accuracy (CA) by six refillable inserts within the electron density CIRS phantom; and (3) spatial resolution (R) with the Jaszczak phantom. Three different respiratory patterns were applied to the phantoms. We developed an open-source package to automatically analyze VA, CA and R. We compared 10 different movement compensation protocols available in the Philips Gemini TF-64 PET/CT (4-, 6-, 8- and 10-time bins, 20%-, 30%-, 40%-window width in Inhale and Exhale). Results The homemade package provided RC values for VA, CA and R of 102 PET images in less than 5 min. Results of the comparison of the 10 different protocols demonstrated the feasibility of the proposed method for quantifying the variations observed qualitatively. Overall, prospective protocols showed better motion compensation than retrospective. The best performance was obtained for the protocol Exhale 30% (0.3 s after maximum Exhale position and window width of 30%) with RCVA=1.6±1.3 , RCCA=0.90±0.09 and RCR=0.6±0.4 . Among retrospective protocols, 8 Phase protocol showed the best performance. Conclusion We provided an open-source package able to automatically evaluate the impact of motion compensation methods on PET image quality. A setup based on commonly available experimental phantoms is recommended. Its application for the comparison of 10 time-based approaches showed that Exhale 30% protocol had the best performance. The proposed framework is not specific to the phantoms and protocols presented on this study

Download or read book Respiratory Motion Modeling for Use in Diagnostic Imaging and Radiation Therapy written by Hadi Fayad and published by . This book was released on 2011 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the most important parameters reducing the sensitivity and specificity in the thoracic and abdominal areas is respiratory motion and associated deformations which represent today an important challenge in medical imaging. In addition, respiratory motion reduces accuracy in image fusion from combined positron emission tomography computed tomography (PET/CT) systems. Solutions presented to date include respiratory synchronized PET and CT acquisitions. However, differences between acquired 4D PET and corresponding CT image series have been reported due to differences in respiration conditions during PET and CT acquisitions. In addition, the radiation dose burden resulting from a 4D CT acquisition may not be justifiable for every patient. The first objective of this thesis was to generate dynamic CT images from one reference CT image; based on deformation matrices obtained from the elastic registration of 4D non attenuation corrected PET images. Such an approach eliminates, on one hand the need for the acquisition of dynamic CT, while at the same time ensuring the good matching between CT and PET images. The second objective was to develop and evaluate methods of building patient specific respiratory motion models and at as a second step more developed generic respiratory motion models. These models relate the internal motion to the parameters of an external surrogate signal (PET respiratory signal or patient's surface) that can be acquired during data acquisition and treatment delivery. Finally, the two developed models were validated and used in the PET respiratory motion and attenuation correction and in radiation therapy applications.

Download or read book Respiratory and Cardiac Gating in PET An Issue of PET Clinics written by Habib Zaidi and published by Elsevier Health Sciences. This book was released on 2013-01-28 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: The complexity of issues associated with gating studies with PET imaging are mostly unknown among practitioners of the field, which is posing a significant danger to those who undergo such studies. This is particularly true for respiratory gating examination. Topics in this issue include both basic and clinical topics, including views from radiation oncology physicians.

Download or read book The Impact of Respiratory Motion Correction Methods on Tumour Detection and Quantification in Positron Emission Tomography written by and published by . This book was released on 2014 with total page 506 pages. Available in PDF, EPUB and Kindle. Book excerpt: The impact on the detectability is compared with that achievable by a higher resolution scanner in order to investigate the importance of correcting for motion to realise the benefit from the increased resolution of future PET scanners.

Download or read book Novel Techniques for Respiratory Motion Estimation and Modelling from Magnetic Resonance Data written by Christian Buerger and published by . This book was released on 2011 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: Imaging such as Magnetic Resonance (MR) imaging and Positron Emission Tomography (PET) are commonly used in the diagnosis and treatment follow-up of cancer. Respiratory motion, however, introduces motion blurring and degrades image quality. As a solution, motion models have been proposed but remain challenging due to the following problems. First, common motion estimation algorithms are computationally complex (and consequently time-consuming) and often have poor robustness when large deformations are present. Second, due to technical limitations of current MR systems, prospective acquisitions are not capable of acquiring images with both high temporal and spatial resolution, which are required for accurate motion estimations. In this thesis, both challenges are addressed. A new registration algorithm has been developed which estimates complex non-rigid motion by a combination of multiple local affine components. This algorithm allows fast and accurate motion estimations and is robust against large deformations due to its adaptive hierarchical structure. Furthermore, a new reconstruction scheme has been developed which retrospectively combines raw data acquired from free-breathing acquisitions to reconstruct multiple images covering the complete range of the breathing cycle. This reconstruction method overcomes the spatial-temporal trade-off and produces near motion-free respiratory images with high isotropic resolution. Both methods are combined to model the continuous deformation of the abdomen during an average breathing cycle, with errors in model predictions of comparable magnitude to the image resolution. A modification of this work is used to allow highly efficient motion compensated reconstructions from short acquisitions under free-breathing.

Download or read book Novel Techniques for Respiratory Motion Estimation and Modeling from MR Data written by Christian Buerger and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Imaging such as Magnetic Resonance (MR) imaging and Positron Emission Tomography (PET) are commonly used in the diagnosis and treatment follow-up of cancer. Respiratory motion, however, introduces motion blurring and degrades image quality. As a solution, motion models have been proposed but remain challenging due to the following problems. First, common motion estimation algorithms are computationally complex (and consequently time-consuming) and often have poor robustness when large deformations are present. Second, due to technical limitations of current MR systems, prospective acquisitions are not capable of acquiring images with both high temporal and spatial resolution, which are required for accurate motion estimations. In this thesis, both challenges are addressed. A new registration algorithm has been developed which estimates complex non-rigid motion by a combination of multiple local affine components. This algorithm allows fast and accurate motion estimations and is robust against large deformations due to its adaptive hierarchical structure. Furthermore, a new reconstruction scheme has been developed which retrospectively combines raw data acquired from free-breathing acquisitions to reconstruct multiple images covering the complete range of the breathing cycle. This reconstruction method overcomes the spatial-temporal trade-off and produces near motion-free respiratory images with high isotropic resolution. Both methods are combined to model the continuous deformation of the abdomen during an average breathing cycle, with errors in model predictions of comparable magnitude to the image resolution. A modification of this work is used to allow highly efficient motion compensated reconstructions from short acquisitions under free-breathing.

Download or read book Effect of Respiratory Motion on Myocardial Perfusion Single Photon Emission Computed Tomography written by 楊佑文 and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Adaptive Motion Compensation in Radiotherapy written by Martin J. Murphy and published by CRC Press. This book was released on 2011-12-14 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: External-beam radiotherapy has long been challenged by the simple fact that patients can (and do) move during the delivery of radiation. Recent advances in imaging and beam delivery technologies have made the solution—adapting delivery to natural movement—a practical reality. Adaptive Motion Compensation in Radiotherapy provides the first detailed treatment of online interventional techniques for motion compensation radiotherapy. This authoritative book discusses: Each of the contributing elements of a motion-adaptive system, including target detection and tracking, beam adaptation, and patient realignment Treatment planning issues that arise when the patient and internal target are mobile Integrated motion-adaptive systems in clinical use or at advanced stages of development System control functions essential to any therapy device operating in a near-autonomous manner with limited human interaction Necessary motion-detection methodology, repositioning techniques, and approaches to interpreting and responding to target movement data in real time Medical therapy with external beams of radiation began as a two-dimensional technology in a three-dimensional world. However, in all but a limited number of scenarios, movement introduces the fourth dimension of time to the treatment problem. Motion-adaptive radiation therapy represents a truly four-dimensional solution to an inherently four-dimensional problem. From these chapters, readers will gain not only an understanding of the technical aspects and capabilities of motion adaptation but also practical clinical insights into planning and carrying out various types of motion-adaptive radiotherapy treatment.