keyword
MENU ▼
Read by QxMD icon Read
search

iterative reconstruction

keyword
https://www.readbyqxmd.com/read/28437983/generation-of-patterned-phase-only-holograms-ppohs
#1
P W M Tsang, Y T Chow, T-C Poon
A fast and non-iterative method for generating a phase-only hologram, hereafter referred to as the patterned-phase-only hologram (PPOH), is reported in this paper. Briefly, a phase mask with a periodic phase pattern is added to the source image, and converted into a hologram. Subsequently, only the phase component is retained as a phase-only hologram. Experimental evaluation reveals that the visual quality of the reconstructed images of the PPOH generated with our proposed method is favorable, and superior to that obtained with existing methods...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437937/use-of-kramers-kronig-relation-in-phase-retrieval-calculation-in-x-ray-spectro-ptychography
#2
Makoto Hirose, Kei Shimomura, Nicolas Burdet, Yukio Takahashi
Coherent diffraction imaging (CDI) is a method for reconstructing the complex-valued image of an object from diffraction intensities by using iterative phasing methods. X-ray ptychography is a scanning type of CDI using X-rays, allowing us to visualize the complex transmission function of an extended specimen. We here propose the use of the Kramers-Kronig relation (KKR) as an additional constraint in phase retrieval algorithms for multiple-energy X-ray ptychography using the absorption edge of a specific element...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437900/model-and-reconstruction-of-a-k-edge-contrast-agent-distribution-with-an-x-ray-photon-counting-detector
#3
Bo Meng, Wenxiang Cong, Yan Xi, Bruno De Man, Jian Yang, Ge Wang
Contrast-enhanced computed tomography (CECT) helps enhance the visibility for tumor imaging. When a high-Z contrast agent interacts with X-rays across its K-edge, X-ray photoelectric absorption would experience a sudden increment, resulting in a significant difference of the X-ray transmission intensity between the left and right energy windows of the K-edge. Using photon-counting detectors, the X-ray intensity data in the left and right windows of the K-edge can be measured simultaneously. The differential information of the two kinds of intensity data reflects the contrast-agent concentration distribution...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437735/detective-quantum-efficiency-dqe-in-pet-scanners-a-simulation-study
#4
George E Karpetas, Christos M Michail, George P Fountos, Nektarios I Kalyvas, Ioannis G Valais, Ioannis S Kandarakis, George S Panayiotakis
The aim of the present study is to introduce the detective quantum efficiency (DQE) for the image quality assessment of positron emission tomography (PET) scanners. For this purpose, a thin layer chromatography (TLC) plane source was simulated using a previously validated, scanner and source geometry, Monte Carlo (MC) model. The model was developed with the Geant4 application for tomographic emission (GATE) MC package and reconstructed images obtained with the software for tomographic image reconstruction (STIR), with cluster computing...
April 12, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/28437011/noise-reduction-and-functional-maps-image-quality-improvement-in-dynamic-ct-perfusion-using-a-new-k-means-clustering-guided-bilateral-filter-kmgb
#5
Francesco Pisana, Thomas Henzler, Stefan Schönberg, Ernst Klotz, Bernhard Schmidt, Marc Kachelrieß
PURPOSE: Dynamic CT perfusion (CTP) consists in repeated acquisitions of the same volume in different time steps, slightly before, during and slightly afterwards the injection of contrast media. Important functional information can be derived for each voxel, which reflect the local hemodynamic properties and hence the metabolism of the tissue. Different approaches are being investigated to exploit data redundancy and prior knowledge for noise reduction of such datasets, ranging from iterative reconstruction schemes to high dimensional filters...
April 24, 2017: Medical Physics
https://www.readbyqxmd.com/read/28432820/the-impact-of-small-motion-on-the-visualization-of-coronary-vessels-and-lesions-in-cardiac-ct-a-simulation-study
#6
Francisco Contijoch, J Webster Stayman, Elliot R McVeigh
PURPOSE: Coronary x-ray computed tomography angiography (CCTA) is used to non-invasively assess coronary artery geometry and has, combined with computational modeling, demonstrated the potential to identify physiologically significant lesions. These measurements require robust and accurate coronary imaging and delineation of vessels in the presence of small motion. This simulation study characterizes the impact of small, uncorrected vessel drifts during data acquisition on the assessment of vessel intensity, diameter, and shape...
April 22, 2017: Medical Physics
https://www.readbyqxmd.com/read/28429371/design-of-a-short-non-uniform-acquisition-protocol-for-quantitative-analysis-in-dynamic-cardiac-spect-imaging-a-retrospective-123-i-mibg-animal-study
#7
Yunlong Zan, Yong Long, Kewei Chen, Biao Li, Qiu Huang, Grant T Gullberg
PURPOSE: Our previous works have found that quantitative analysis of (123) I-MIBG kinetics in the heart with dynamic single-photon emission computed tomography (SPECT) offers the potential to quantify the innervation integrity at an early stage of left ventricular hypertrophy. However, conventional protocols involving a long acquisition time for dynamic imaging reduce the animal survival rate and thus make longitudinal analysis difficult. The goal of this work was to develop a procedure to reduce the total acquisition time by selecting non-uniform acquisition times for projection views while maintaining the accuracy and precision of estimated physiologic parameters...
April 21, 2017: Medical Physics
https://www.readbyqxmd.com/read/28429055/diagnostic-value-of-fourth-generation-iterative-reconstruction-algorithm-with-low-dose-ct-protocol-in-assessment-of-mesorectal-fascia-invasion-in-rectal-cancer-comparison-with-magnetic-resonance
#8
Davide Ippolito, Silvia Girolama Drago, C R Talei Franzesi, Alessandra Casiraghi, Sandro Sironi
PURPOSE: The purpose of the article is to compare the diagnostic performance about radiation dose and image quality of low-dose CT with iterative reconstruction algorithm (iDose4) and standard-dose CT in the assessment of mesorectal fascia (MRF) invasion in rectal cancer patients. MATERIALS AND METHODS: Ninety-one patients with biopsy-proven primary rectal adenocarcinoma underwent CT staging: 42 underwent low-dose CT, 49 underwent standard CT protocol. Low-dose contrast-enhanced MDCT scans were performed on a 256 (ICT, Philips) scanner using 120 kV, automated mAs modulation, iDose4 iterative reconstruction algorithm...
April 20, 2017: Abdominal Radiology
https://www.readbyqxmd.com/read/28428471/motion-frozen-imaging-by-gated-myocardial-perfusion-single-photon-emission-computed-tomography-using-multi-focus-fan-beam-collimator-in-thallium-201-study
#9
Kaito Takahashi, Takashi Takeuchi, Yoshiyuki Hosokai, Hayato Odagiri, Haruo Saito
PURPOSE: This study aimed to evaluate the statistical noise of motion-frozen (MF) image generated by gated myocardial perfusion single photon emission computed tomography (SPECT) imaging using IQ · SPECT and to determine the optimal acquisition and reconstruction parameters for MF image using IQ · SPECT. METHODS: A movement cardiac phantom and static cardiac phantom were used to acquire the MF images. The acquisition times used were different in 8 and 16 frames per R-R interval, and varying reconstruction parameters (subset and iteration) were used...
2017: Nihon Hoshasen Gijutsu Gakkai Zasshi
https://www.readbyqxmd.com/read/28428468/multicenter-investigation-of-the-effective-dose-for-whole-body-ct-scanning
#10
Toshimitsu Sato, Yukihiro Saito, Nobutoshi Saito, Makoto Ooba
OBJECTIVE: To study whether the actual radiation exposure is different between computed tomography (CT) scanners and medical centers when the same patient is scanned, we investigated the actual effective doses for a whole body (Chest-Pelvis) CT scan in a multicenter study. MATERIALS AND METHODS: Data from subjects were collected using 12 CT scanners at six medical centers in Yamagata city. Effective-dose data were acquired by scanning the same phantom (ATOM Dosimetry Phantoms Model702-B) using 120 kV tube voltage...
2017: Nihon Hoshasen Gijutsu Gakkai Zasshi
https://www.readbyqxmd.com/read/28419591/application-of-spin-echoes-in-the-regime-of-weak-dephasing-to-t1-mapping-of-the-lung
#11
Jakob Assländer, Steffen J Glaser, Jürgen Hennig
PURPOSE: This work presents an approach to mapping the entire lung's proton density and T1 within a single breath-hold and analyzes the apparent T1 when exciting with a spin echo generating pulse in comparison to a standard gradient echo acquisition. METHODS: An inversion-recovery SNAPSHOT-FLASH sequence with a stack-of-stars k-space readout with a golden angle increment was modified to use a spin echo generating radiofrequency-pulse for excitation. Data of five volunteers were acquired on a 3T scanner and image reconstruction was performed by an iterative algorithm adopted from MR-Fingerprinting...
April 17, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28417170/reduced-dose-ct-with-model-based-iterative-reconstruction-compared-to-standard-dose-ct-of-the-chest-abdomen-and-pelvis-in-oncology-patients-intra-individual-comparison-study-on-image-quality-and-lesion-conspicuity
#12
Linda Nayeli Morimoto, Aya Kamaya, Isabelle Boulay-Coletta, Dominik Fleischmann, Lior Molvin, Lu Tian, George Fisher, Jia Wang, Jürgen K Willmann
PURPOSE: To compare image quality and lesion conspicuity of reduced dose (RD) CT with model-based iterative reconstruction (MBIR) compared to standard dose (SD) CT in patients undergoing oncological follow-up imaging. METHODS: Forty-four cancer patients who had a staging SD CT within 12 months were prospectively included to undergo a weight-based RD CT with MBIR. Radiation dose was recorded and tissue attenuation and image noise of four tissue types were measured...
April 17, 2017: Abdominal Radiology
https://www.readbyqxmd.com/read/28414380/iterative-reconstruction-of-scene-depth-with-fidelity-based-on-light-field-data
#13
Chang Liu, Jun Qiu, Songnian Zhao
Depth reconstruction from the light field, as a depth extracting approach, is a vibrant research field in computational imaging. In this paper, depth reconstruction from the light field was approached as an optimization problem by analyzing the forward and inverse models. The forward and inverse models present the connection between the light field and the depth of the scene. We proposed an iterative method for scene depth reconstruction with fidelity from 4D light field data. The objective function of the optimization problem entails three terms, of which the matching term is used as the fidelity term, while the gradient term and classification term constitute the penalty terms...
April 10, 2017: Applied Optics
https://www.readbyqxmd.com/read/28412013/investigation-of-the-imaging-characteristics-of-the-albira-ii-small-animal-pet-system-for-18-f-68-ga-and-64-cu
#14
Ali Asgar Attarwala, Yvonne Wanjiku Karanja, Deni Hardiansyah, Chiara Romanó, Mareike Roscher, Björn Wängler, Gerhard Glatting
AIM: In this study the performance characteristics of the Albira II PET sub-system and the response of the system for the following radionuclides (18)F, (68)Ga and (64)Cu was analyzed. MATERIALS AND METHODS: The Albira II tri-modal system (Bruker BioSpin MRI GmbH, Ettlingen, Germany) is a pre-clinical device for PET, SPECT and CT. The PET sub-system uses single continuous crystal detectors of lutetium yttrium orthosilicate (LYSO). The detector assembly consists of three rings of 8 detector modules...
April 12, 2017: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/28410683/evaluation-of-automatic-image-quality-assessment-in-chest-ct-a-human-cadaver-study
#15
Caro Franck, An De Crop, Bieke De Roo, Peter Smeets, Merel Vergauwen, Tom Dewaele, Mathias Van Borsel, Eric Achten, Tom Van Hoof, Klaus Bacher
PURPOSE: The evaluation of clinical image quality (IQ) is important to optimize CT protocols and to keep patient doses as low as reasonably achievable. Considering the significant amount of effort needed for human observer studies, automatic IQ tools are a promising alternative. The purpose of this study was to evaluate automatic IQ assessment in chest CT using Thiel embalmed cadavers. METHODS: Chest CT's of Thiel embalmed cadavers were acquired at different exposures...
April 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28410386/radiation-dose-reduction-in-pediatric-great-vessel-stent-computed-tomography-using-iterative-reconstruction-a-phantom-study
#16
Annemarie M den Harder, Dominika Suchá, Pieter J van Doormaal, Ricardo P J Budde, Pim A de Jong, Arnold M R Schilham, Johannes M P J Breur, Tim Leiner
BACKGROUND: To study dose reduction using iterative reconstruction (IR) for pediatric great vessel stent computed tomography (CT). METHODS: Five different great vessel stents were separately placed in a gel-containing plastic holder within an anthropomorphic chest phantom. The stent lumen was filled with diluted contrast gel. CT acquisitions were performed at routine dose, 52% and 81% reduced dose and reconstructed with filtered back projection (FBP) and IR. Objective image quality in terms of noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) as well as subjective image quality were evaluated...
2017: PloS One
https://www.readbyqxmd.com/read/28409258/impact-of-knowledge-based-iterative-model-reconstruction-on-myocardial-late-iodine-enhancement-in-computed-tomography-and-comparison-with-cardiac-magnetic-resonance
#17
Yuki Tanabe, Teruhito Kido, Akira Kurata, Naoki Fukuyama, Takahiro Yokoi, Tomoyuki Kido, Teruyoshi Uetani, Mani Vembar, Amar Dhanantwari, Shinichi Tokuyasu, Natsumi Yamashita, Teruhito Mochizuki
We evaluated the image quality and diagnostic performance of late iodine enhancement computed tomography (LIE-CT) with knowledge-based iterative model reconstruction (IMR) for the detection of myocardial infarction (MI) in comparison with late gadolinium enhancement magnetic resonance imaging (LGE-MRI). The study investigated 35 patients who underwent a comprehensive cardiac CT protocol and LGE-MRI for the assessment of coronary artery disease. The CT protocol consisted of stress dynamic myocardial CT perfusion, coronary CT angiography (CTA) and LIE-CT using 256-slice CT...
April 13, 2017: International Journal of Cardiovascular Imaging
https://www.readbyqxmd.com/read/28408290/automated-template-based-brain-localization-and-extraction-for-fetal-brain-mri-reconstruction
#18
Sébastien Tourbier, Clemente Velasco-Annis, Vahid Taimouri, Patric Hagmann, Reto Meuli, Simon K Warfield, Meritxell Bach Cuadra, Ali Gholipour
Most fetal brain MRI reconstruction algorithms rely only on brain tissue-relevant voxels of low-resolution (LR) images to enhance the quality of inter-slice motion correction and image reconstruction. Consequently the fetal brain needs to be localized and extracted as a first step, which is usually a laborious and time consuming manual or semi-automatic task. We have proposed in this work to use age-matched template images as prior knowledge to automatize brain localization and extraction. This has been achieved through a novel automatic brain localization and extraction method based on robust template-to-slice block matching and deformable slice-to-template registration...
April 10, 2017: NeuroImage
https://www.readbyqxmd.com/read/28406049/evaluation-of-reduced-dose-ct-for-acute-non-traumatic-abdominal-pain-evaluation-of-diagnostic-accuracy-in-comparison-to-standard-dose-ct
#19
Ahmed E Othman, Malte Niklas Bongers, Dominik Zinsser, Christoph Schabel, Julian L Wichmann, Rami Arshid, Mike Notohamiprodjo, Konstantin Nikolaou, Fabian Bamberg
Background Patients with acute non-traumatic abdominal pain often undergo abdominal computed tomography (CT). However, abdominal CT is associated with high radiation exposure. Purpose To evaluate diagnostic performance of a reduced-dose 100 kVp CT protocol with advanced modeled iterative reconstruction as compared to a linearly blended 120 kVp protocol for assessment of acute, non-traumatic abdominal pain. Material and Methods Two radiologists assessed 100 kVp and linearly blended 120 kVp series of 112 consecutive patients with acute non-traumatic pain (onset < 48 h) regarding image quality, noise, and artifacts on a five-point Likert scale...
January 1, 2017: Acta Radiologica
https://www.readbyqxmd.com/read/28405477/influence-of-adaptive-statistical-iterative-reconstruction-algorithm-on-image-quality-in-coronary-computed-tomography-angiography
#20
Helle Precht, Jesper Thygesen, Oke Gerke, Kenneth Egstrup, Dag Waaler, Jess Lambrechtsen
BACKGROUND: Coronary computed tomography angiography (CCTA) requires high spatial and temporal resolution, increased low contrast resolution for the assessment of coronary artery stenosis, plaque detection, and/or non-coronary pathology. Therefore, new reconstruction algorithms, particularly iterative reconstruction (IR) techniques, have been developed in an attempt to improve image quality with no cost in radiation exposure. PURPOSE: To evaluate whether adaptive statistical iterative reconstruction (ASIR) enhances perceived image quality in CCTA compared to filtered back projection (FBP)...
December 2016: Acta Radiologica Open
keyword
keyword
83320
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"