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https://www.readbyqxmd.com/read/28742032/architecture-of-an-ultrasound-system-for-continuous-real-time-high-frame-rate-imaging
#1
Enrico Boni, Luca Bassi, Alessandro Dallai, Valentino Meacci, Alessandro Ramalli, Monica Scaringella, Francesco Guidi, Stefano Ricci, Piero Tortoli
High frame rate (HFR) imaging methods based on the transmission of defocused or plane waves rather than focused beams are increasingly popular. However, the production of HFR images poses severe requirements both in the transmission and the reception sections of ultrasound scanners. In particular, major technical difficulties arise if the images must be continuously produced in real-time, i.e. without any acquisition interruption nor loss of data. This paper presents the implementation of the real-time HFR compounded imaging application in the ULA-OP 256 research platform...
July 20, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28741892/dose-comparison-between-gafchromic-film-xio-and-monaco-treatment-planning-systems-in-a-novel-pelvic-phantom-that-contains-a-titanium-hip-prosthesis
#2
Nicholas Ade, F C P du Plessis
The presence of metallic prostheses during external beam radiotherapy of malignancies in the pelvic region has the potential to strongly influence the dose distribution to the target and to tissue surrounded by the prostheses. This study systematically investigates the perturbation effects of unilateral titanium prosthesis on 6 and 15 MV photon beam dose distributions using Gafchromic EBT2 film measurements in a novel pelvic phantom made out of a stack of nylon slices. Comparisons were also made between the film data and dose calculations made on XiO and Monaco treatment planning systems...
July 25, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28741597/motion-compensation-for-cone-beam-ct-using-fourier-consistency-conditions
#3
Martin Berger, Yan Xia, Wolfgang Aichinger, Katrin Mentl, Mathias Unberath, Andre Aichert, Christian Riess, Joachim Hornegger, Rebecca Fahrig, Andreas Konrad Maier
In cone-beam CT, involuntary patient motion and inaccurate or irreproducible scanner motion substantially degrades image quality. To avoid artifacts this motion needs to be estimated and compensated during image reconstruction. In previous work we showed that Fourier Consistency Conditions (FCC) can be used in fan-beam CT to estimate motion in the sinogram domain. This work extends the FCC to 3-D cone-beam CT. We derive an efficient cost function to compensate for 3-D motion using 2-D detector translations...
July 25, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28741596/the-response-of-mri-contrast-parameters-in-i-in-vitro-i-tissues-and-tissue-mimicking-phantoms-to-fractionation-by-histotripsy
#4
Steven Paul Allen, Eli Vlaisavljevich, Jiaqi Shi, Luis Hernandez-Garcia, Charles A Cain, Zhen Xu, Timothy L Hall
Histotripsy is a non-invasive, focused ultrasound lesioning technique that can ablate precise volumes of soft tissue using a novel mechanical fractionation mechanism. Previous research suggests that magnetic resonance imaging (MRI) may be a sensitive image-based feedback mechanism for histotripsy. However, there are insufficient data to form some unified understanding of the response of the MR contrast mechanisms in tissues to histotripsy. In this paper, we investigate the response of the MR contrast parameters R1, R2, and the apparent diffusion coefficient (ADC) to various treatment levels of histotripsy in in-vitro porcine liver, kidney, muscle, and blood clot as well in formulations of bovine red blood cells suspended in agar gel...
July 25, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28741595/3d-range-modulator-for-scanned-particle-therapy-development-monte-carlo-simulations-and-experimental-evaluation
#5
Yuri Simeonov, Uli Weber, Petar Penchev, Toke Printz Ringbæk, Christoph Schuy, Stephan Brons, Rita Engenhart-Cabillic, Jens Bliedtner, Klemens Zink
The purpose of this work was to design and manufacture a 3D range-modulator for scanned particle therapy. The modulator is intended to create a highly conformal dose distribution with only one fixed energy, simultaneously reducing considerably the treatment time. As a proof of concept, a 3D range-modulator was developed for a spherical target volume with a diameter of 5 cm, placed at a depth of 25 cm in a water phantom. It consists of a large number of thin pins with a well-defined shape and different lengths to modulate the necessary shift of the Bragg peak...
July 25, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28741577/comparison-of-new-generation-renal-artery-denervation-systems-assessing-lesion-size-and-thermodynamics-using-a-thermochromic-liquid-crystal-phantom-model
#6
Sara I Al Raisi, Michael T Barry, Pierre Qian, Abhishek Bhaskaran, Jim Pouliopoulos, Pramesh Kovoor
AIM: To evaluate and compare lesion dimensions and thermodynamics of the new generation multi-electrode Symplicity Spyral and the new generation multi-electrode EnligHTN renal artery denervation systems, using a thermochromic liquid crystal phantom model. METHODS AND RESULTS: A previously described renal artery phantom model was used as a platform for radiofrequency ablation. A total of 32 radiofrequency ablations were performed using multi-electrode Symplicity Spyral (n=16) and new generation EnligHTN systems (n=16)...
July 25, 2017: EuroIntervention
https://www.readbyqxmd.com/read/28740918/impact-of-moving-target-on-measurement-accuracy-in-3d-and-4d-pet-imaging-a-phantom-study
#7
Yunfeng Cui, James Bowsher, Jing Cai, Fang-Fang Yin
PURPOSE: The purpose of this study was to evaluate the impact of tumor motion on maximum standardized uptake value (SUVmax) and metabolic tumor volume (MTV) measurements in both 3-dimensional and respiratory-correlated, 4-dimensional positron emission tomography (PET) imaging. We also evaluated the effect of implementing different attenuation correction methods in 4-dimensional PET image reconstruction on SUVmax and MTV. METHODS AND MATERIALS: An anthropomorphic thorax phantom with a spherical ball as a surrogate for a tumor was used...
January 2017: Advances in Radiation Oncology
https://www.readbyqxmd.com/read/28740907/functional-imaging-equivalence-and-proof-of-concept-for-image-guided-adaptive-radiotherapy-with-fixed-gantry-and-rotating-couch
#8
Ilana Feain, Chun-Chien Shieh, Paul White, Ricky O'Brien, Sandra Fisher, William Counter, Peter Lazarakis, David Stewart, Simon Downes, Michael Jackson, Siddhartha Baxi, Brendan Whelan, Kuldeep Makhija, Chen-Yu Huang, Michael Barton, Paul Keall
PURPOSE: The purpose of this article is to present the first imaging experiments to demonstrate the functional equivalence between a conventional rotational gantry and a fixed-beam imaging geometry, and the feasibility of an iterative image-reconstruction technique under gravitational deformation. METHODS AND MATERIALS: Experiments were performed using an Elekta Axesse with Agility MLC and XVI, a custom-built rotating phantom stage, a Catphan QA phantom, and a porcine heart...
October 2016: Advances in Radiation Oncology
https://www.readbyqxmd.com/read/28739392/large-improvement-of-rf-transmission-efficiency-and-reception-sensitivity-for-human-in-vivo-31-p-mrs-imaging-using-ultrahigh-dielectric-constant-materials-at-7t
#9
Byeong-Yeul Lee, Xiao-Hong Zhu, Sebastian Rupprecht, Michael T Lanagan, Qing X Yang, Wei Chen
In vivo(31)P MRS provides a unique and important imaging tool for studying high-energy phosphate metabolism and bioenergetics noninvasively. However, compared to (1)H MRS, (31)P MRS with a relatively low gyromagnetic ratio (γ) has a lower and limited sensitivity even at ultrahigh field. The proof of concept has been recently demonstrated that the use of high dielectric constant (HDC) materials between RF coil and object sample could increase MRI signal and reduce required RF transmission power for reaching the same RF pulse flip angle in the region of interest...
July 21, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28739379/ultrasound-induced-bubble-clusters-in-tissue-mimicking-agar%C3%A2-phantoms
#10
Pooya Movahed, Wayne Kreider, Adam D Maxwell, Barbrina Dunmire, Jonathan B Freund
Therapeutic ultrasound can drive bubble activity that damages soft tissues. To study the potential mechanisms of such injury, transparent agar tissue-mimicking phantoms were subjected to multiple pressure wave bursts of the kind being considered specifically for burst wave lithotripsy. A high-speed camera recorded bubble activity during each pulse. Various agar concentrations were used to alter the phantom's mechanical properties, especially its stiffness, which was varied by a factor of 3.5. However, the maximum observed bubble radius was insensitive to stiffness...
July 21, 2017: Ultrasound in Medicine & Biology
https://www.readbyqxmd.com/read/28739211/investigating-the-surface-dose-contribution-of-intrafractional-kv-imaging-in-cyberknife-based-stereotactic-radiosurgery
#11
Abdulmecit Canbolat, Faruk Zorlu, Pervin Hurmuz, Mete Yeginer, Gokhan Ozyigit
CyberKnife treatment consists of hundreds of noncoplanar beams and numerous intrafractional images that can be taken during a single treatment fraction; thus, doses because of imaging should be considered in this technique. The aim of this study is to investigate the in-field and out-of-field surface doses induced from kV imaging system during stereotactic radiosurgery (SRS) treatment. The imaging-induced surface doses were measured at the center of the imaging field and within ±15-cm distance from the center in both craniocaudal and lateral directions...
July 21, 2017: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://www.readbyqxmd.com/read/28739143/prediction-of-time-integrated-activity-coefficients-in-prrt-using-simulated-dynamic-pet-and-a-pharmacokinetic-model
#12
Deni Hardiansyah, Ali Asgar Attarwala, Peter Kletting, Felix M Mottaghy, Gerhard Glatting
PURPOSE: To investigate the accuracy of predicted time-integrated activity coefficients (TIACs) in peptide-receptor radionuclide therapy (PRRT) using simulated dynamic PET data and a physiologically based pharmacokinetic (PBPK) model. METHODS: PBPK parameters were estimated using biokinetic data of 15 patients after injection of (152±15)MBq of (111)In-DTPAOC (total peptide amount (5.78±0.25)nmol). True mathematical phantoms of patients (MPPs) were the PBPK model with the estimated parameters...
July 21, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28737194/-face-protective-patches-do-not-reduce-facial-pressure-ulcers-in-a-simulated-model-of-non-invasive-ventilation
#13
Hugo Riquelme M, David Wood V, Santiago Martínez F, Fernando Carmona M, Axel Peña V, Adriana Wegner A
Noninvasive ventilation (NIV) frequently involves the development of facial pressure ulcers (FPU). Its prevention considers the empirical use of protective patches between skin and mask, in order to reduce the pressure exerted by it. OBJECTIVES: To evaluate the effect of protective patches on the pressure exerted by the facial mask, and its impact on the programmed ventilatory parameters. METHOD: Bilevel NIV simulated model using full face mask in phantom with a physiological airway (ALS PRO +) in supine position...
June 2017: Revista Chilena de Pediatría
https://www.readbyqxmd.com/read/28737163/plane-dependent-ml-scatter-scaling-3d-extension-of-the-2d-simulated-single-scatter-sss-estimate
#14
Ahmadreza Rezaei, Koen Salvo, Thomas Vahle, Vladimir Panin, Michael Casey, Fernando Boada, Michel Defrise, Johan Nuyts
Scatter correction is typically done using a simulation of the single scatter, which is then scaled to account for multiple scatters and other possible model mismatches. This scaling factor is determined by fitting the simulated scatter sinogram to the measured sinogram, using only counts measured along LORs that do not intersect the patient body, i.e. 'scatter-tails'. Extending previous work, we propose to scale the scatter with a plane dependent factor, which is determined as an additional unknown in the maximum likelihood (ML) reconstructions, using counts in the entire sinogram rather than only the 'scatter-tails'...
July 24, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28737014/clinical-implementation-of-an-exit-detector-based-dose-reconstruction-tool-for-helical-tomotherapy-delivery-quality-assurance
#15
Shrikant Deshpande, Aitang Xing, Peter Metcalfe, Lois Holloway, Philip Vial, Mark Geurts
PURPOSE: To validate the accuracy of an exit detector based dose reconstruction tool for Helical Tomotherapy (HT) delivery quality assurance (DQA). METHODS AND MATERIAL: Exit detector based DQA tool was developed for patient specific HT treatment verification. The tool performs a dose reconstruction on the planning image using the sinogram measured by the HT exit detector with no objects in the beam (i.e. static couch), and compares the reconstructed dose to the planned dose...
July 24, 2017: Medical Physics
https://www.readbyqxmd.com/read/28736982/understanding-the-influence-of-flow-velocity-wall-motion-filter-pulse-repetition-frequency-and-aliasing-on-power-doppler-image-quantification
#16
Maricy R Martins, Wellington P Martins, Carlos A M Soares, Andre H Miyague, Marek J Kudla, Theo Z Pavan
OBJECTIVES: Although power Doppler imaging has been used to quantify tissue and organ vascularity, many studies showed that limitations in defining adequate ultrasound machine settings and attenuation make such measurements complex to be achieved. However, most of these studies were conducted by using the output of proprietary software, such as Virtual Organ computer-aided analysis (GE Healthcare, Kretz, Zipf, Austria); therefore, many conclusions may not be generalizable because of unknown settings and parameters used by the software...
July 24, 2017: Journal of Ultrasound in Medicine: Official Journal of the American Institute of Ultrasound in Medicine
https://www.readbyqxmd.com/read/28736917/true-constructive-interference-in-the-steady-state-trueciss
#17
Tom Hilbert, Damien Nguyen, Jean-Philippe Thiran, Gunnar Krueger, Tobias Kober, Oliver Bieri
PURPOSE: To introduce a novel time-efficient method, termed true constructive interference in the steady state (trueCISS), that not only solves the problem of banding artifacts for balanced steady-state free precession (bSSFP) but also provides its genuine, that is, true, on-resonant signal. METHODS: After a compressed sensing reconstruction from a set of highly undersampled phase-cycled bSSFP scans, the local off-resonance, relaxation time ratio, and equilibrium magnetization are voxel-wise estimated using a dictionary-based fitting routine...
July 24, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28736826/impact-of-respiratory-motion-and-acquisition-settings-on-spect-liver-dosimetry-for-radioembolization
#18
Remco Bastiaannet, Max A Viergever, Hugo W A M de Jong
PURPOSE: Respiratory motion may impose significant inaccuracies on emission activity estimation in quantitative SPECT. This effect may be a major issue in dosimetry as used in management of liver radioembolization. The purpose of this study was to investigate the impact of respiratory motion on radioembolization liver dosimetry for different SPECT acquisition settings. METHODS: In a series of SPECT/CT Monte Carlo simulations using several digital XCAT phantoms, the following parameters were varied: breathing/non-breathing, liver tumor size (0...
July 24, 2017: Medical Physics
https://www.readbyqxmd.com/read/28736704/visualization-of-photoacoustic-images-in-a-limited-view-measuring-system-using-eigenvalues-of-a-photoacoustic-transmission-matrix
#19
Hiroshi Abe, Tsuyoshi Shiina
Photoacoustic imaging is a unique imaging method that involves extracting information from points at different depths, an advantage of ultrasound imaging, while maintaining functional information, a key feature of conventional photo imaging. This makes it easy to add functional images to ultrasound images by adding a laser pulse source to the conventional ultrasound imaging device and detecting a photo-ultrasound signal via a conventional ultrasound probe. One challenge when using normal one-dimensional (1D) probes and generating photoacoustic images is the limited-view problem, in which artefacts are observed due to the positions of the ultrasound transducers...
December 2017: Photoacoustics
https://www.readbyqxmd.com/read/28736670/wavefront-sensorless-adaptive-optics-oct-with-the-done-algorithm-for-in-vivo-human-retinal-imaging-invited
#20
Hans R G W Verstraete, Morgan Heisler, Myeong Jin Ju, Daniel Wahl, Laurens Bliek, Jeroen Kalkman, Stefano Bonora, Yifan Jian, Michel Verhaegen, Marinko V Sarunic
In this report, which is an international collaboration of OCT, adaptive optics, and control research, we demonstrate the Data-based Online Nonlinear Extremum-seeker (DONE) algorithm to guide the image based optimization for wavefront sensorless adaptive optics (WFSL-AO) OCT for in vivo human retinal imaging. The ocular aberrations were corrected using a multi-actuator adaptive lens after linearization of the hysteresis in the piezoelectric actuators. The DONE algorithm succeeded in drastically improving image quality and the OCT signal intensity, up to a factor seven, while achieving a computational time of 1 ms per iteration, making it applicable for many high speed applications...
April 1, 2017: Biomedical Optics Express
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