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iterative reconstruction

Atul Ingle, Tomy Varghese, William Sethares
Percutaneous needle-based liver ablation procedures are becoming increasingly common for treatment of small isolated tumors in hepatocellular carcinoma patients who are not candidates for surgery. Rapid three dimensional visualization of liver ablations has potential clinical value because it can enable interventional radiologists to plan and execute needle-based ablation procedures with real time feedback. Ensuring the right volume of tissue is ablated is desirable to avoid recurrence of tumors from residual untreated cancerous cells...
November 29, 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Seitaro Oda, Daisuke Utsunomiya, Takeshi Nakaura, Yoshinori Funama, Hideaki Yuki, Masafumi Kidoh, Kenichiro Hirata, Narumi Taguchi, Keiichi Honda, Hiroko Takaoka, Yuji Iyama, Kazuhiro Katahira, Katsuo Noda, Shuichi Oshima, Shinichi Tokuyasu, Yasuyuki Yamashita
RATIONALE AND OBJECTIVES: We compared the effect of iterative model reconstruction (IMR), filtered back projection (FBP), and hybrid iterative reconstruction (HIR) on coronary artery calcium (CAC) scoring. MATERIALS AND METHODS: CAC scans of 30 consecutive patients (18 men and 12 women, age 70.1 ± 12.2 years) were reconstructed with FBP, HIR, and IMR, and the image noise was measured on all images. Two radiologists independently measured the CAC scores using semiautomated software, and interobserver agreement was evaluated...
November 29, 2016: Academic Radiology
Yingmei Wang, Ge Wang, Shuwei Mao, Wenxiang Cong, Zhilong Ji, Jian-Feng Cai, Yangbo Ye
Reducing radiation dose is an important goal in medical computed tomography (CT), for which interior tomography is an effective approach. There have been interior reconstruction algorithms for monochromatic CT, but in reality, X-ray sources are polychromatic. Using a polychromatic acquisition model and motivated by framelet-based image processing algorithms, in this paper, we propose an interior reconstruction algorithm to obtain an image with spectral information assuming only one scan with a current energy-integrating detector...
November 22, 2016: Journal of X-ray Science and Technology
Simon Arridge, Paul Beard, Marta Betcke, Ben Cox, Nam Huynh, Felix Lucka, Olumide Ogunlade, Edward Zhang
Current 3D photoacoustic tomography (PAT) systems offer either high image quality or high frame rates but are not able to deliver high spatial and temporal resolution simultaneously, which limits their ability to image dynamic processes in living tissue (4D PAT). A particular example is the planar Fabry-Pérot (FP) photoacoustic scanner, which yields high-resolution 3D images but takes several minutes to sequentially map the incident photoacoustic field on the 2D sensor plane, point-by-point. However, as the spatio-temporal complexity of many absorbing tissue structures is rather low, the data recorded in such a conventional, regularly sampled fashion is often highly redundant...
December 21, 2016: Physics in Medicine and Biology
M Rebai, L Giacomelli, A Milocco, M Nocente, D Rigamonti, M Tardocchi, F Camera, C Cazzaniga, Z J Chen, T F Du, T S Fan, A Giaz, Z M Hu, T Marchi, X Y Peng, G Gorini
A Single-crystal Diamond (SD) detector prototype was installed at Joint European Torus (JET) in 2013 and the achieved results have shown its spectroscopic capability of measuring 2.5 MeV neutrons from deuterium plasmas. This paper presents measurements of the SD response function to monoenergetic neutrons, which is a key point for the development of a neutron spectrometer based on SDs and compares them with Monte Carlo simulations. The analysis procedure allows for a good reconstruction of the experimental results...
November 2016: Review of Scientific Instruments
J Howard, M Kocan, S Lisgo, R Reichle
An optical coherence imaging system is presently being designed for impurity transport studies and other applications on ITER. The wide variation in magnetic field strength and pitch angle (assumed known) across the field of view generates additional Zeeman-polarization-weighting information that can improve the reliability of tomographic reconstructions. Because background reflected light will be somewhat depolarized analysis of only the polarized fraction may be enough to provide a level of background suppression...
November 2016: Review of Scientific Instruments
H Q Liu, J P Qian, Y X Jie, W X Ding, D L Brower, Z Y Zou, W M Li, H Lian, S X Wang, Y Yang, L Zeng, T Lan, Y Yao, L Q Hu, X D Zhang, B N Wan
A double-pass, radially viewing, far-infrared laser-based POlarimeter-INTerferometer (POINT) system utilizing the three-wave technique has been implemented for diagnosing the plasma current and electron density profiles in the Experimental Advanced Superconducting Tokamak (EAST). POINT has been operated routinely during the most recent experimental campaign and provides continuous 11 chord line-integrated Faraday effect and density measurement throughout the entire plasma discharge for all heating schemes and all plasma conditions (including ITER relevant scenario development)...
November 2016: Review of Scientific Instruments
Katharina Hahn, Harald Schöndube, Karl Stierstorfer, Joachim Hornegger, Frédéric Noo
PURPOSE: Recent reports indicate that model-based iterative reconstruction methods may improve image quality in computed tomography (CT). One difficulty with these methods is the number of options available to implement them, including the selection of the forward projection model and the penalty term. Currently, the literature is fairly scarce in terms of guidance regarding this selection step, whereas these options impact image quality. Here, the authors investigate the merits of three forward projection models that rely on linear interpolation: the distance-driven method, Joseph's method, and the bilinear method...
December 2016: Medical Physics
Tia E Plautz, V Bashkirov, V Giacometti, R F Hurley, R P Johnson, P Piersimoni, H F-W Sadrozinski, R W Schulte, A Zatserklyaniy
PURPOSE: To evaluate the spatial resolution of proton CT using both a prototype proton CT scanner and Monte Carlo simulations. METHODS: A custom cylindrical edge phantom containing twelve tissue-equivalent inserts with four different compositions at varying radial displacements from the axis of rotation was developed for measuring the modulation transfer function (MTF) of a prototype proton CT scanner. Two scans of the phantom, centered on the axis of rotation, were obtained with a 200 MeV, low-intensity proton beam: one scan with steps of 4°, and one scan with the phantom continuously rotating...
December 2016: Medical Physics
Christopher M Rank, Thorsten Heußer, Andreas Wetscherek, Martin T Freitag, Oliver Sedlaczek, Heinz-Peter Schlemmer, Marc Kachelrieß
PURPOSE: Positron emission tomography (PET) of the thorax region is impaired by respiratory patient motion. To account for motion, the authors propose a new method for PET/magnetic resonance (MR) respiratory motion compensation (MoCo), which uses highly undersampled MR data with acquisition times as short as 1 min/bed. METHODS: The proposed PET/MR MoCo method (4D jMoCo PET) uses radial MR data to estimate the respiratory patient motion employing MR joint motion estimation and image reconstruction with temporal median filtering...
December 2016: Medical Physics
Stephen C Moore, Mi-Ae Park, Zhe Liu, Morgan C Lyon, Lindsay C Johnson, Victor H Lushear, James G Westberg, Scott D Metzler
PURPOSE: One approach to preclinical single-photon emission computed tomography (SPECT) imaging that provides both high resolution and high sensitivity is based on imaging a mouse inside a collimating tube; many magnified pinhole projection images from a small target region, e.g., the heart, can be recorded simultaneously on multiple detectors with little multiplexing since each pinhole aperture's opening angle is restricted to view mostly the target organ. However, to obtain complete data for reconstruction, it may be necessary to scan the mouse through the target region of the tube...
December 2016: Medical Physics
Geoff Nelson, Meng Wu, Cameron Hinkel, Ganesh Krishna, Tobias Funk, Jarrett Rosenberg, Rebecca Fahrig
PURPOSE: Electromagnetic navigation bronchoscopy (ENB) provides improved targeting accuracy during transbronchial biopsies of suspicious nodules. The greatest weakness of ENB-based guidance is the registration divergence that exists between the planning CT, acquired days or weeks before the intervention, and the patient on the table on the day of the intervention. Augmenting ENB guidance with real-time tomosynthesis imaging during the intervention could mitigate the divergence and further improve the yield of ENB-guided transbronchial biopsies...
December 2016: Medical Physics
Justin Solomon, Alexandre Ba, François Bochud, Ehsan Samei
PURPOSE: To use novel voxel-based 3D printed textured phantoms in order to compare low-contrast detectability between two reconstruction algorithms, FBP (filtered-backprojection) and SAFIRE (sinogram affirmed iterative reconstruction) and determine what impact background texture (i.e., anatomical noise) has on estimating the dose reduction potential of SAFIRE. METHODS: Liver volumes were segmented from 23 abdominal CT cases. The volumes were characterized in terms of texture features from gray-level co-occurrence and run-length matrices...
December 2016: Medical Physics
Ana Okariz, Teresa Guraya, Maider Iturrondobeitia, Julen Ibarretxe
The SIRT (Simultaneous Iterative Reconstruction Technique) algorithm is commonly used in Electron Tomography to calculate the original volume of the sample from noisy images, but the results provided by this iterative procedure are strongly dependent on the specific implementation of the algorithm, as well as on the number of iterations employed for the reconstruction. In this work, a methodology for selecting the iteration number of the SIRT reconstruction that provides the most accurate segmentation is proposed...
November 19, 2016: Ultramicroscopy
Minglin Yang, Yueqian Wu, Kuan Fang Ren, Xinqing Sheng
Due to special characteristics of nondiffraction and self reconstruction, the Bessel beams have attracted wide attention in optical trapping and appear to be a dramatic alternative to Gaussian beams. We present in this paper an efficient approach based on the surface integral equations (SIE) to compute the radiation pressure force (RPF) exerted on arbitrary shaped homogeneous particles by high-order Bessel vortex beam (HOBVB). The incident beam is described by vector expressions perfectly satisfy Maxwell's equations...
November 28, 2016: Optics Express
Yang Lou, Kun Wang, Alexander A Oraevsky, Mark A Anastasio
Optoacoustic tomography (OAT), also known as photoacoustic tomography, is a rapidly emerging hybrid imaging technique that possesses great potential for a wide range of biomedical imaging applications. In OAT, a laser is employed to illuminate the tissue of interest and acoustic signals are produced via the photoacoustic effect. From these data, an estimate of the distribution of the absorbed optical energy density within the tissue is reconstructed, referred to as the object function. This quantity is defined, in part, by the distribution of light fluence within the tissue that is established by the laser source...
December 1, 2016: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Johannes Budjan, Holger Haubenreisser, Thomas Henzler, Sonja Sudarski, Michaela Schmidt, Christina Doesch, Ibrahim Akin, Martin Borggrefe, Nadja M Meßner, Stefan O Schoenberg, Ulrike I Attenberger, Theano Papavassiliu
To generate a patient-friendly, time-efficient cardiac MRI examination protocol, a highly accelerated real-time CINE MR sequence (SSIR) was acquired in the idle time in between contrast injection and late gadolinium enhancement phase. 20 consecutive patients underwent a cardiac MRI examination including a multi-breath-hold sequence as gold standard (Ref) as well as SSIR sequences with (SSIR-BH) and without breath-hold (SSIR-nonBH). SSIR sequences were acquired 4 minutes after gadolinium injection. Right- (RV) and left-ventricular (LV) volumetric functional parameters were evaluated and compared between Ref and SSIR sequences...
December 1, 2016: Scientific Reports
Naoki Sunaguchi, Yoshiki Yamakoshi, Takahito Nakajima
This study investigates shear wave phase map reconstruction using a limited number of color flow images (CFIs) acquired with a color Doppler ultrasound imaging instrument. We propose an efficient reconstruction method to considerably reduce the number of CFIs required for reconstruction and compare this method with Fourier analysis-based color Doppler shear wave imaging. The proposed method uses a two-step phase reconstruction process, including an initial phase map derived from four CFIs using an advanced iterative algorithm of optical interferometry...
November 30, 2016: Ultrasonic Imaging
Xin Liu, Hongkai Wang, Zhuangzhi Yan
Dynamic fluorescence molecular tomography (FMT) plays an important role in drug delivery research. However, the majority of current reconstruction methods focus on solving the stationary FMT problems. If the stationary reconstruction methods are applied to the time-varying fluorescence measurements, the reconstructed results may suffer from a high level of artifacts. In addition, based on the stationary methods, only one tomographic image can be obtained after scanning one circle projection data. As a result, the movement of fluorophore in imaged object may not be detected due to the relative long data acquisition time (typically >1 min)...
November 1, 2016: Biomedical Optics Express
Eriko Maeda, Nobuo Tomizawa, Shigeaki Kanno, Koichiro Yasaka, Takatoshi Kubo, Kenji Ino, Rumiko Torigoe, Kuni Ohtomo
BACKGROUND: We aimed to assess and compare the influence of Forward projected model-based Iterative Reconstruction SoluTion (FIRST), a recently introduced full iterative reconstruction method, on radiation doses and image quality with that of Adaptive Iterative Dose Reduction (AIDR) 3D for 320-row cardiac computed tomography (CT). METHODS: A total of 184 patients subjected to single-beat reconstruction cardiac CT were retrospectively included. The first 89 patients received standard radiation doses; their data were reconstructed using AIDR 3D, whereas the last 95 patients received in average 20% reduction in tube current; their data were reconstructed using FIRST...
November 9, 2016: Journal of Cardiovascular Computed Tomography
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