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https://www.readbyqxmd.com/read/28088225/using-low-cost-drones-to-map-malaria-vector-habitats
#1
Andy Hardy, Makame Makame, Dónall Cross, Silas Majambere, Mwinyi Msellem
BACKGROUND: There is a growing awareness that if we are to achieve the ambitious goal of malaria elimination, we must compliment indoor-based vector control interventions (such as bednets and indoor spraying) with outdoor-based interventions such as larval source management (LSM). The effectiveness of LSM is limited by our capacity to identify and map mosquito aquatic habitats. This study provides a proof of concept for the use of a low-cost (< $1000) drone (DJI Phantom) for mapping water bodies in seven sites across Zanzibar including natural water bodies, irrigated and non-irrigated rice paddies, peri-urban and urban locations...
January 14, 2017: Parasites & Vectors
https://www.readbyqxmd.com/read/28086909/fast-detection-and-data-compensation-for-electrodes-disconnection-in-long-term-monitoring-of-dynamic-brain-electrical-impedance-tomography
#2
Ge Zhang, Meng Dai, Lin Yang, Weichen Li, Haoting Li, Canhua Xu, Xuetao Shi, Xiuzhen Dong, Feng Fu
BACKGROUND: Electrode disconnection is a common occurrence during long-term monitoring of brain electrical impedance tomography (EIT) in clinical settings. The data acquisition system suffers remarkable data loss which results in image reconstruction failure. The aim of this study was to: (1) detect disconnected electrodes and (2) account for invalid data. METHODS: Weighted correlation coefficient for each electrode was calculated based on the measurement differences between well-connected and disconnected electrodes...
January 7, 2017: Biomedical Engineering Online
https://www.readbyqxmd.com/read/28081009/influence-of-wall-thickness-and-diameter-on-arterial-shear-wave-elastography-a-phantom-and-finite-element-study
#3
Elira Maksuti, Fabiano Bini, Stefano Fiorentini, Giulia Blasi, Matthew Urban, Franco Marinozzi, Matilda Larsson
Quantitative, non-invasive and local measurements of arterial mechanical properties could be highly beneficial for early diagnosis of cardiovascular disease and follow up of treatment. Arterial Shear Wave Elastography (SWE) and wave velocity dispersion analysis have previously been applied to measure arterial stiffness. Arterial wall thickness (h) and inner diameter (D) vary with age and pathology and may influence the shear wave propagation. Nevertheless, the effect of arterial geometry in SWE has not yet been systematically investigated...
January 12, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28081004/reverberant-shear-wave-fields-and-estimation-of-tissue-properties
#4
Kevin J Parker, Juvenal Ormachea, Fernando Zvietcovich, Benjamin Castaneda
The determination of shear wave speed is an important subject in the field of elastography, since elevated shear wave speeds can be directly linked to increased stiffness of tissues. MRI and ultrasound scanners are frequently used to detect shear waves and a variety of estimators are applied to calculate the underlying shear wave speed. The estimators can be relatively simple if plane wave behavior is assumed with a known direction of propagation. However, multiple reflections from organ boundaries and internal inhomogeneities and mode conversions can create a complicated field in time and space...
January 12, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28079754/ultrasound-guided-needle-technique-accuracy-prospective-comparison-of-passive-magnetic-tracking-versus-unassisted-echogenic-needle-localization
#5
Angela N Johnson, Jeffery S Peiffer, Nahi Halmann, Luke Delaney, Cindy A Owen, Jeff Hersh
BACKGROUND AND OBJECTIVES: Ultrasound-guided regional anesthesia facilitates an approach to sensitive targets such as nerve clusters without contact or inadvertent puncture. We compared accuracy of needle placement with a novel passive magnetic ultrasound needle guidance technology (NGT) versus conventional ultrasound (CU) with echogenic needles. METHODS: Sixteen anesthesiologists and 19 residents performed a series of 16 needle insertion tasks each, 8 using NGT (n = 280) and 8 using CU (n = 280), in high-fidelity porcine phantoms...
January 11, 2017: Regional Anesthesia and Pain Medicine
https://www.readbyqxmd.com/read/28079527/binary-moving-blocker-based-scatter-correction-in-cone-beam-computed-tomography-with-width-truncated-projections-proof-of-concept
#6
Ho Lee, Benjamin Fahimian, Lei Xing
This paper proposes a binary moving-blocker (BMB)-based technique for scatter correction in cone-beam computed tomography (CBCT). In concept, a beam blocker consisting of lead strips, mounted in front of the x-ray tube, moves rapidly in and out of the beam during a single gantry rotation. The projections are acquired in alternating phases of blocked and unblocked cone beams, where the blocked phase results in a stripe pattern in the width direction. To derive the scatter map from the blocked projections, one-dimensional B-Spline interpolation/extrapolation is applied by using the detected information in the shaded regions...
January 12, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28079526/a-measurement-based-generalized-source-model-for-monte-carlo-dose-simulations-of-ct-scans
#7
Xin Ming, Yuanming Feng, Ransheng Liu, Chengwen Yang, Li Zhou, Hezheng Zhai, Jun Deng
The goal of this study is to present a generalized source model (GSM) for accurate Monte Carlo dose simulations of CT scans based solely on the measurement data without a priori knowledge of scanner specifications. The proposed generalized source model consists of an extended circular source located at x-ray target level with its energy spectrum, source distribution and fluence distribution derived from a set of measurement data conveniently available in the clinic. Specifically, the central axis percent depth dose (PDD) curves measured in water and the cone output factors measured in air were used to derive the energy spectrum and the source distribution respectively with a Levenberg-Marquardt algorithm...
January 12, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28079525/a-model-based-3d-patient-specific-pre-treatment-qa-method-for-vmat-using-the-epid
#8
Peter M McCowan, Ganiyu Asuni, Timothy van Beek, Eric Van Uytven, Kaden Kujanpaa, Boyd McCurdy
This study reports the development and validation of the first model-based, 3D patient dose reconstruction method for pre-treatment quality assurance using EPID images. The method is also investigated for sensitivity to potential MLC delivery errors. Each cine-mode EPID image acquired during plan delivery was processed using a previously developed back-projection dose reconstruction model providing a 3D dose estimate on the CT simulation data. Validation was carried out using 24 SBRT-VMAT patient plans by comparing: 1) ion chamber point dose measurements in a solid water phantom, 2) the treatment planning system (TPS) predicted 3D dose to the EPID reconstructed 3D dose in a solid water phantom, and 3) the TPS predicted 3D dose to the EPID and our forward predicted reconstructed 3D dose in the patient (CT data)...
January 12, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28079257/a-safe-cheap-and-easy-to-use-isotropic-diffusion-mri-phantom-for-clinical-and-multicenter-studies
#9
Pim Pullens, Piet Bladt, Jan Sijbers, Andrew I R Maas, Paul M Parizel
PURPOSE: Since Diffusion Weighted Imaging (DWI) data acquisition and processing are not standardized, substantial differences in DWI derived measures such as Apparent Diffusion Coefficient (ADC) may arise which are related to the acquisition or MRI processing method, but not to the sample under study. Quality assurance using a standardized test object, or phantom, is a key factor in standardizing DWI across scanners. METHODS: Current diffusion phantoms are either complex to use, not available in larger quantities, contain substances unwanted in a clinical environment, or are expensive...
January 12, 2017: Medical Physics
https://www.readbyqxmd.com/read/28077627/a-feasibility-study-on-the-use-of-phantoms-with-statistical-lung-masses-for-determining-the-uncertainty-in-the-dose-absorbed-by-the-lung-from-broad-beams-of-incident-photons-and-neutrons
#10
Atiyeh Ebrahimi Khankook, Hashem Miri Hakimabad, Laleh Rafat Motavalli
Computational models of the human body have gradually become crucial in the evaluation of doses absorbed by organs. However, individuals may differ considerably in terms of organ size and shape. In this study, the authors sought to determine the energy-dependent standard deviations due to lung size of the dose absorbed by the lung during external photon and neutron beam exposures. One hundred lungs with different masses were prepared and located in an adult male International Commission on Radiological Protection (ICRP) reference phantom...
January 10, 2017: Journal of Radiation Research
https://www.readbyqxmd.com/read/28076368/functional-laterality-of-task-evoked-activation-in-sensorimotor-cortex-of-preterm-infants-an-optimized-3-t-fmri-study-employing-a-customized-neonatal-head-coil
#11
Lukas Scheef, Jurek A Nordmeyer-Massner, Adam Pr Smith-Collins, Nicole Müller, Gaby Stegmann-Woessner, Jacob Jankowski, Jürgen Gieseke, Mark Born, Hermann Seitz, Peter Bartmann, Hans H Schild, Klaas P Pruessmann, Axel Heep, Henning Boecker
BACKGROUND: Functional magnetic resonance imaging (fMRI) in neonates has been introduced as a non-invasive method for studying sensorimotor processing in the developing brain. However, previous neonatal studies have delivered conflicting results regarding localization, lateralization, and directionality of blood oxygenation level dependent (BOLD) responses in sensorimotor cortex (SMC). Amongst the confounding factors in interpreting neonatal fMRI studies include the use of standard adult MR-coils providing insufficient signal to noise, and liberal statistical thresholds, compromising clinical interpretation at the single subject level...
2017: PloS One
https://www.readbyqxmd.com/read/28075330/building-an-open-source-simulation-platform-of-acoustic-radiation-force-based-breast-elastography
#12
Yu Wang, Bo Peng, Jingfeng Jiang
Ultrasound-based elastography techniques including quasi-static strain elastography (SE), acoustic radiation force Impulse (ARFI) imaging, point shear wave elastography (pSWE) and supersonic shear imaging (SSI) have been used to differentiate breast tumors. The objective of this study is to extend a previously published virtual simulation platform of SE toward acoustic radiation force-based breast elastography. The proposed platform inherited four key components from the previously published virtual SE platform: an ultrasound simulator (Field II), a mesh generator (Tetgen), a finite element (FE) solver (FEBio) and a visualization and data processing package (VTK)...
January 11, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28074541/comparison-of-respiratory-motion-suppression-techniques-for-4d-flow-mri
#13
Petter Dyverfeldt, Tino Ebbers
PURPOSE: The purpose of this work was to assess the impact of respiratory motion and to compare methods for suppression of respiratory motion artifacts in 4D Flow MRI. METHODS: A numerical 3D aorta phantom was designed based on an aorta velocity field obtained by computational fluid mechanics. Motion-distorted 4D Flow MRI measurements were simulated and several different motion-suppression techniques were evaluated: Gating with fixed acceptance window size, gating with different window sizes in inner and outer k-space, and k-space reordering...
January 11, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28074530/slice-profile-and-b1-corrections-in-2d-magnetic-resonance-fingerprinting
#14
Dan Ma, Simone Coppo, Yong Chen, Debra F McGivney, Yun Jiang, Shivani Pahwa, Vikas Gulani, Mark A Griswold
PURPOSE: The goal of this study is to characterize and improve the accuracy of 2D magnetic resonance fingerprinting (MRF) scans in the presence of slice profile (SP) and B1 imperfections, which are two main factors that affect quantitative results in MRF. METHODS: The SP and B1 imperfections are characterized and corrected separately. The SP effect is corrected by simulating the radiofrequency pulse in the dictionary, and the B1 is corrected by acquiring a B1 map using the Bloch-Siegert method before each scan...
January 11, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28074018/evaluation-of-dose-homogeneity-in-cone-beam-breast-computed-tomography
#15
Giovanni Mettivier, Matilde Costa, Nico Lanconelli, Anna Ianiro, Mariagabriella Pugliese, Maria Quarto, Paolo Russo
The aim of this study is to determine, via measurements on phantoms and Monte Carlo (MC) simulations, the dose distribution of absorbed dose in a cone-beam breast computed tomography scan. The absorbed dose volume distribution was measured inside a polyethylene cylindrical phantom, simulating adipose breast tissue, using LiF:Mg,Ti thermoluminescence dosimeters. A reasonable agreement (between 2 and 8%) between the simulated and measured data was observed. The 3D distribution of absorbed dose was evaluated at 40, 60 and 80 kV in a phantom simulating a pendant breast...
January 10, 2017: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/28073637/variable-angle-stereo-imaging-for-rapid-patient-position-correction-in-an-in-house-real-time-position-monitoring-system
#16
Sankar Arumugam, Mark Sidhom, Daniel Truant, Aitang Xing, Mark Udovitch, Lois Holloway
PURPOSE: To develop and validate a variable angle stereo image based position correction methodology in an X-ray based in-house online position monitoring system. MATERIALS AND METHODS: A stereo imaging module that enables 3D position determination and couch correction of the patient based on images acquired at any arbitrary angle and arbitrary angular separation was developed and incorporated to the in-house SeedTracker real-time position monitoring system. The accuracy of the developed system was studied by imaging an anthropomorphic phantom implanted with radiopaque markers set to known offset positions from its reference position in an Elekta linear accelerator (LA) and associated XVI imaging system...
January 7, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28073068/comparative-analysis-of-isotropic-diffusion-weighted-imaging-sequences
#17
Sebastian Vellmer, Rüdiger Stirnberg, Daniel Edelhoff, Dieter Suter, Tony Stöcker, Ivan I Maximov
Visualisation of living tissue structure and function is a challenging problem of modern imaging techniques. Diffusion MRI allows one to probe in vivo structures on a micrometer scale. However, conventional diffusion measurements are time-consuming procedures, because they require several measurements with different gradient directions. Considerable time savings are therefore possible by measurement schemes that generate an isotropic diffusion weighting in a single shot. Multiple approaches for generating isotropic diffusion weighting are known and have become very popular as useful tools in clinical research...
December 30, 2016: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28072813/a-case-report-on-red-ear-syndrome-with-tinnitus-successfully-treated-with-transcranial-random-noise-stimulation
#18
Peter M Kreuzer, Veronika Vielsmeier, Timm B Poeppl, Berthold Langguth
BACKGROUND: The red ear syndrome represents a rare symptom complex consisting of auricular erythema associated with painful and burning sensations. It has been described in combination with tinnitus rarely. It has been hypothesized to be etiologically related to altered trigeminal afferent input, temporomandibular disorders, and thalamic dysfunction. OBJECTIVES: The initial objective of applying transcranial random noise stimulation (tRNS) in a case of red ear syndrome in combination with tinnitus was the alleviation of the phantom sounds...
January 2017: Pain Physician
https://www.readbyqxmd.com/read/28072584/verification-of-respiratory-gated-radiotherapy-with-new-real-time-tumour-tracking-radiotherapy-system-using-cine-epid-images-and-a-log-file
#19
Takehiro Shiinoki, Hideki Hanazawa, Yuki Yuasa, Koya Fujimoto, Takuya Uehara, Keiko Shibuya
<u>Purposes:</u> A combined system comprising the TrueBeam linear accelerator and a new real-time tumour-tracking radiotherapy system, SyncTraX, was installed at our institution. The objectives of this study are to develop a method for the verification of respiratory-gated radiotherapy with SyncTraX using cine electronic portal image device (EPID) images and a log file and to verify this treatment in clinical cases. <u>Methods and Materials:</u> Respiratory-gated radiotherapy was performed using TrueBeam and the SyncTraX system...
January 10, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28072580/in-vivo-real-time-cavitation-imaging-in-moving-organs
#20
B Arnal, J Baranger, C Demene, M Tanter, M Pernot
The stochastic nature of cavitation implies visualization of the cavitation cloud in real-time and in a discriminative manner for the safe use of focused ultrasound therapy. This visualization is sometimes possible with standard echography, but it strongly depends on the quality of the scanner, and is hindered by difficulty in discriminating from highly reflecting tissue signals in different organs. A specific approach would then permit clear validation of the cavitation position and activity. Detecting signals from a specific source with high sensitivity is a major problem in ultrasound imaging...
January 10, 2017: Physics in Medicine and Biology
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