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https://www.readbyqxmd.com/read/29346116/4d-computed-tomography-scans-for-conformal-thoracic-treatment-planning-is-a-single-scan-sufficient-to-capture-thoracic-tumor-motion
#1
Yolanda D Tseng, Landon Wootton, Matthew Nyflot, Smith Apisarnthanarax, Ramesh Rengan, Charles Bloch, George Sandison, Sara St James
Four dimensional computed tomography (4DCT) scans are routinely used in radiation therapy to determine the internal treatment volume for targets that are moving (e.g. lung tumors). The use of these studies has allowed clinicians to create target volumes based upon the motion of the tumor during the imaging study. The purpose of this work is to determine if a target volume based on a single 4DCT scan at simulation is sufficient to capture thoracic motion. Phantom studies were performed to determine expected differences between volumes contoured on 4DCT scans and those on the evaluation CT scans (slow scans)...
January 18, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29340290/tailoring-four-dimensional-cone-beam-ct-acquisition-settings-for-fiducial-marker-based-image-guidance-in-radiation-therapy
#2
Peng Jin, Niek van Wieringen, Maarten C C M Hulshof, Arjan Bel, Tanja Alderliesten
Use of four-dimensional cone-beam CT (4D-CBCT) and fiducial markers for image guidance during radiation therapy (RT) of mobile tumors is challenging due to the trade-off among image quality, imaging dose, and scanning time. This study aimed to investigate different 4D-CBCT acquisition settings for good visibility of fiducial markers in 4D-CBCT. Using these 4D-CBCTs, the feasibility of marker-based 4D registration for RT setup verification and manual respiration-induced motion quantification was investigated...
April 2018: Journal of Medical Imaging
https://www.readbyqxmd.com/read/29339575/dynamic-pet-image-reconstruction-integrating-temporal-regularization-associated-with-respiratory-motion-correction-for-applications-in-oncology
#3
Thibaut Merlin, Dimitris Visvikis, Philippe Fernandez, Frederic Lamare
Respiratory motion reduces both the qualitative and quantitative accuracy of PET images in oncology. This impact is more significant for quantitative applications based on kinetic modeling, where dynamic acquisitions are associated with limited statistics due to the necessity of enhanced temporal resolution. The aim of this study is to address these drawbacks by combining within a unique reconstruction algorithm in dynamic PET imaging, a respiratory motion correction approach, as well as a temporal regularization...
January 17, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29338327/respiratory-gated-pet-ct-for-pulmonary-lesion-characterisation-promises-and-problems
#4
Russell Frood, Garry McDermott, Andrew Scarsbrook
2-Deoxy-2-(18Fluorine)-fluoro-D-glucose (FDG) positron emission tomography/computed tomography (PET/CT) is an integral part of lung carcinoma staging and frequently used in the assessment of solitary pulmonary nodules. However, a limitation of conventional 3D PET/CT when imaging the thorax is its susceptibility to motion artefact which blurs the signal from the lesion resulting in inaccurate representation of size and metabolic activity. Respiratory gated (4D) PET/CT aims to negate the effects of motion artefact and provide a more accurate interpretation of pulmonary nodules and lymphadenopathy...
January 17, 2018: British Journal of Radiology
https://www.readbyqxmd.com/read/29251777/an-adaptive-motion-regularization-technique-to-support-sliding-motion-in-deformable-image-registration
#5
Yabo Fu, Shi Liu, H Harold Li, Hua Li, Deshan Yang
PURPOSE: Isotropic smoothing has been conventionally used to regularize deformation vector fields (DVFs) in deformable image registration (DIR). However, the isotropic smoothing method enforces global smoothness and therefore cannot accurately model the complex tissue deformation, such as sliding motion at organ boundaries. To accurately model and estimate sliding tissue motion, an adaptive direction-dependent DVF regularization technique was developed in this study. METHODS: A DVF is computed and updated iteratively by minimizing the intensity differences between the images...
December 18, 2017: Medical Physics
https://www.readbyqxmd.com/read/29238828/validation-of-the-strain-assessment-of-an-abdominal-phantom-aortic-aneurysm-comparison-of-results-obtained-from-magnetic-resonance-imaging-measurements-and-stereovision-measurements
#6
Yufei Wang, David Joannic, Patrick Juillion, Aurélien Monnet, Patrick Delassus, Alain Lalande, Jean-Francois Fontaine
Predicating aortic aneurysm ruptures is a complex problem that has been investigated by many research teams over several decades. Work on this issue is notably complex and involves both the mechanical behavior of the artery and the blood flow. Magnetic resonance imaging (MRI) can provide measurements concerning the shape of an organ and the blood that flows through it. Measuring local distortion of the artery wall is the first essential element to evaluate a ruptured artery. This paper aims to demonstrate the feasibility of this measure by MRI on phantom realistic abdominal aortic aneurysm (AAA)...
December 13, 2017: Journal of Biomechanical Engineering
https://www.readbyqxmd.com/read/29235989/motion-vector-field-phase-to-amplitude-resampling-for-4d-motion-compensated-cone-beam-ct
#7
Sebastian Sauppe, Julian Kuhm, Marcus Brehm, Pascal Paysan, Dieter Seghers, Marc Kachelriess
We propose a phase-to-amplitude resampling (PTAR) method to reduce motion blurring in motion-compensated (MoCo) 4D cone-beam CT (CBCT) image reconstruction, without increasing the computational complexity of the motion vector field (MVF) estimation approach. PTAR is able to improve the image quality in reconstructed 4D volumes including both regular and irregular respiration patterns. The PTAR approach starts with a robust phase gating procedure for the initial MVF estimation and then switches to a phase-adapted amplitude gating method...
December 13, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29226240/optical-computed-tomography-for-spatially-isotropic-four-dimensional-imaging-of-live-single-cells
#8
Laimonas Kelbauskas, Rishabh Shetty, Bin Cao, Kuo-Chen Wang, Dean Smith, Hong Wang, Shi-Hui Chao, Sandhya Gangaraju, Brian Ashcroft, Margaret Kritzer, Honor Glenn, Roger H Johnson, Deirdre R Meldrum
Quantitative three-dimensional (3D) computed tomography (CT) imaging of living single cells enables orientation-independent morphometric analysis of the intricacies of cellular physiology. Since its invention, x-ray CT has become indispensable in the clinic for diagnostic and prognostic purposes due to its quantitative absorption-based imaging in true 3D that allows objects of interest to be viewed and measured from any orientation. However, x-ray CT has not been useful at the level of single cells because there is insufficient contrast to form an image...
December 2017: Science Advances
https://www.readbyqxmd.com/read/29219119/density-overwrites-of-internal-tumor-volumes-in-intensity-modulated-proton-therapy-plans-for-mobile-lung-tumors
#9
Pablo Botas, Clemens Grassberger, Gregory Sharp, Harald Paganetti
The purpose of this study was to investigate Internal Tumor Volume (ITV) density overwrite strategies to minimize Intensity Modulated Proton Therapy (IMPT) plan degradation of mobile lung tumors. Four planning paradigms were compared for nine lung cancer patients. IGTV and ICTV structures were defined encompassing their respective volumes in every 4DCT phase. The paradigms use different planning CT (pCT) created from the Average Intensity Projection (AIP) of the 4DCT, overwriting the density within the IGTV to account for movement...
December 8, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29218271/magnetic-resonance-imaging-in-precision-radiation-therapy-for-lung-cancer
#10
REVIEW
Hannah Bainbridge, Ahmed Salem, Rob H N Tijssen, Michael Dubec, Andreas Wetscherek, Corinne Van Es, Jose Belderbos, Corinne Faivre-Finn, Fiona McDonald
Radiotherapy remains the cornerstone of curative treatment for inoperable locally advanced lung cancer, given concomitantly with platinum-based chemotherapy. With poor overall survival, research efforts continue to explore whether integration of advanced radiation techniques will assist safe treatment intensification with the potential for improving outcomes. One advance is the integration of magnetic resonance imaging (MRI) in the treatment pathway, providing anatomical and functional information with excellent soft tissue contrast without exposure of the patient to radiation...
December 2017: Translational Lung Cancer Research
https://www.readbyqxmd.com/read/29205937/experience-with-an-abdominal-compression-band-for-radiotherapy-of-upper-abdominal-tumours
#11
Rebecca Van Gelder, Shelley Wong, Andrew Le, Alexander Podreka, Adam Briggs, Carol Haddad, Nicholas Hardcastle
INTRODUCTION: Radiotherapy outcomes are influenced by treatment delivery geometric accuracy and organ-at-risk dose. The location of abdominal structures such as the liver, kidneys and tumour volumes can be strongly influenced by respiratory motion. This increases geometric uncertainty and dose to organs-at-risk. One common method of minimising respiratory motion is abdominal compression (AC). METHODS: Fifteen patients being treated for radiotherapy to upper abdominal tumours were analysed...
December 5, 2017: Journal of Medical Radiation Sciences
https://www.readbyqxmd.com/read/29195556/immobilization-for-carbon-ion-beam-ablation-of-cardiac-structures-in-a-porcine-model
#12
Matthias Prall, Anna Eichhorn, Daniel Richter, H Immo Lehmann, Anna Constantinescu, Robert Kaderka, Patrick Lugenbiel, Dierk Thomas, Christoph Bert, Douglas L Packer, Marco Durante, Christian Graeff
INTRODUCTION: Whereas hadron therapy of static targets is clinically established, treatment of moving organs remains a challenge. One strategy is to minimize motion of surrounding tissue mechanically and to mitigate residual motion with an appropriate irradiation technique. In this technical note, we present and characterize such an immobilization technique for a novel noncancerous application: the irradiation of small targets in hearts with scanned carbon ion beams in a porcine model for elimination of arrhythmias...
November 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/29194940/the-development-of-a-4d-treatment-planning-methodology-to-simulate-the-tracking-of-central-lung-tumors-in-an-mri-linac
#13
Shahad M Al-Ward, Anthony Kim, Claire McCann, Mark Ruschin, Patrick Cheung, Arjun Sahgal, Brian M Keller
PURPOSE: Targeting and tracking of central lung tumors may be feasible on the Elekta MRI-linac (MRL) due to the soft-tissue visualization capabilities of MRI. The purpose of this work is to develop a novel treatment planning methodology to simulate tracking of central lung tumors with the MRL and to quantify the benefits in OAR sparing compared with the ITV approach. METHODS: Full 4D-CT datasets for five central lung cancer patients were selected to simulate the condition of having 4D-pseudo-CTs derived from 4D-MRI data available on the MRL with real-time tracking capabilities...
December 1, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/29193781/impact-of-tumour-motion-compensation-and-delineation-methods-on-fdg-pet-based-dose-painting-plan-quality-for-nsclc-radiation-therapy
#14
Hannah Mary Thomas, Paul E Kinahan, James Jebaseelan E Samuel, Stephen R Bowen
INTRODUCTION: To quantitatively estimate the impact of different methods for both boost volume delineation and respiratory motion compensation of [18F] FDG PET/CT images on the fidelity of planned non-uniform 'dose painting' plans to the prescribed boost dose distribution. METHODS: Six locally advanced non-small cell lung cancer (NSCLC) patients were retrospectively reviewed. To assess the impact of respiratory motion, time-averaged (3D AVG), respiratory phase-gated (4D GATED) and motion-encompassing (4D MIP) PET images were used...
November 28, 2017: Journal of Medical Imaging and Radiation Oncology
https://www.readbyqxmd.com/read/29173902/impact-of-deformable-image-registration-accuracy-on-thoracic-images-with-different-regularization-weight-parameter-settings
#15
Hideharu Miura, Shuichi Ozawa, Minoru Nakao, Kengo Furukawa, Yoshiko Doi, Hideo Kawabata, Masahiro Kenjou, Yasushi Nagata
PURPOSE: We assessed the deformable image registration (DIR) accuracy of thoracic images under different regularization weights using commercially available DIR software. METHODS: The thoracic 4-dimensional (4D) CT images of 10 patients were used. The datasets for these patients were provided by DIR-lab (www.dir-lab.com) and included a coordinate list of 300 anatomic landmarks that had been manually identified. The ANAtomically CONstrained Deformation Algorithm (ANACONDA) of RayStation (RaySearch Laboratories, Stockholm, Sweden) was used to deform the peak-inhale to peak-exhale images under different regularization weights (4, 40, 400-default setting, 1500, 4000, 10,000, 15,000, 20,000, 30,000, and 40,000)...
October 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/29151545/-novel-perfusion-evaluation-method-using-phase-ratio-image-map-in-head-4d-ct
#16
Tomomi Ohmura, Yongbum Lee, Noriyuki Takahashi, Hideto Toyoshima
PURPOSE: CT perfusion (CTP) is a powerful tool for the assessment of cerebrovascular disease. However, CTP maps are significantly different depending on CTP software and algorithm, even when using identical image data. We developed a phase-ratio image map (PI map), which was a novel perfusion map, without using CTP software. The purpose of this study was to investigate the usefulness of the PI map by comparing it with a positron emission tomography (PET) image. METHODS: Twenty patients (16 men, 4 women; mean age: 61...
2017: Nihon Hoshasen Gijutsu Gakkai Zasshi
https://www.readbyqxmd.com/read/29148430/low-dose-4d-cardiac-imaging-in-small-animals-using-dual-source-micro-ct
#17
Matthew Holbrook, Darin P Clark, Cristian T Badea
Micro-CT is widely used in preclinical studies, generating substantial interest in extending its capabilities in functional imaging applications such as blood perfusion and cardiac function. However, imaging cardiac structure and function in mice is challenging due to their small size and rapid heart rate. To overcome these challenges, we propose and compare improvements on two strategies for cardiac gating in dual-source, preclinical micro-CT: fast prospective gating (PG) and uncorrelated retrospective gating (RG)...
November 17, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29142240/robust-segmentation-of-the-full-cerebral-vasculature-in-4d-ct-of-suspected-stroke-patients
#18
Midas Meijs, Ajay Patel, Sil C van de Leemput, Mathias Prokop, Ewoud J van Dijk, Frank-Erik de Leeuw, Frederick J A Meijer, Bram van Ginneken, Rashindra Manniesing
A robust method is presented for the segmentation of the full cerebral vasculature in 4-dimensional (4D) computed tomography (CT). The method consists of candidate vessel selection, feature extraction, random forest classification and postprocessing. Image features include among others the weighted temporal variance image and parameters, including entropy, of an intensity histogram in a local region at different scales. These histogram parameters revealed to be a strong feature in the detection of vessels regardless of shape and size...
November 15, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29136282/principal-component-reconstruction-pcr-for-cine-cbct-with-motion-learning-from-2d-fluoroscopy
#19
Hao Gao, Yawei Zhang, Lei Ren, Fang-Fang Yin
PURPOSE: This work aims to generate cine CT images (i.e., 4D images with high temporal resolution) based on a novel principal component reconstruction (PCR) technique with motion learning from 2D fluoroscopic training images. METHODS: In the proposed PCR method, the matrix factorization is utilized as an explicit low-rank regularization of 4D images that are represented as a product of spatial principal components and temporal motion coefficients. The key hypothesis of PCR is that temporal coefficients from 4D images can be reasonably approximated by temporal coefficients learned from 2D fluoroscopic training projections...
November 14, 2017: Medical Physics
https://www.readbyqxmd.com/read/29134472/real-time-wireless-tumor-tracking-during-breast-conserving-surgery
#20
Natasja Janssen, Roeland Eppenga, Marie-Jeanne Vrancken Peeters, Frederieke van Duijnhoven, Hester Oldenburg, Jos van der Hage, Emiel Rutgers, Jan-Jakob Sonke, Koert Kuhlmann, Theo Ruers, Jasper Nijkamp
PURPOSE: To evaluate a novel surgical navigation system for breast conserving surgery (BCS), based on real-time tumor tracking using the Calypso[Formula: see text] 4D Localization System (Varian Medical Systems Inc., USA). Navigation-guided breast conserving surgery (Nav-BCS) was compared to conventional iodine seed-guided BCS ([Formula: see text]I-BCS). METHODS: Two breast phantom types were produced, containing spherical and complex tumors in which wireless transponders (Nav-BCS) or a iodine seed ([Formula: see text]I-BCS) were implanted...
November 13, 2017: International Journal of Computer Assisted Radiology and Surgery
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