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https://www.readbyqxmd.com/read/29149320/organic-scintillator-for-real-time-neutron-dosimetry
#1
Kyle A Beyer, Angela Di Fulvio, Liliana Stolarczyk, Wiktor Parol, Natalia Mojzeszek, Renata Kopéc, Shaun D Clarke, Sara A Pozzi
We developed a radiation detector based on an organic scintillator for spectrometry and dosimetry of out-of-field secondary neutrons from clinical proton beams. The detector consists of an EJ-299-34 crystalline organic scintillator, coupled by fiber optic cable to a silicon photomultiplier (SiPM). Proof of concept measurements were taken with 137Cs and 252Cf, and corresponding simulations were performed in MCNPX-PoliMi. Despite its small size, the detector is able to discriminate between neutron and gamma-rays via pulse shape discrimination...
November 15, 2017: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/29148575/effects-of-spot-parameters-in-pencil-beam-scanning-treatment-planning
#2
Aafke Christine Kraan, Nicolas Depauw, Ben Clasie, Marina Giunta, Tom Madden, Hanne M Kooy
BACKGROUND: Spot size σ (in-air at isocenter), inter-spot spacing d, and spot charge q influence dose delivery efficiency and plan quality in Intensity Modulated Proton Therapy (IMPT) treatment planning. The choice and range of parameters varies among different manufacturers. The goal of this work is to demonstrate the influence of the spot parameters on dose quality and delivery in IMPT treatment plans, to show their interdependence, and to make practitioners aware of the spot parameter values for a certain facility...
November 17, 2017: Medical Physics
https://www.readbyqxmd.com/read/29148434/the-cutting-away-of-potential-secondary-electron-tracks-explains-the-effects-of-beam-size-and-detector-wall-density-in-small-field-photon-dosimetry
#3
Hui Khee Looe, Bjoern Delfs, Daniela Poppinga, Ping Jiang, Dietrich Harder, Bjoern Poppe
The well-known field-size dependent overresponse in small-field photon-beam dosimetry of solid-state detectors equipped with very thin sensitive volumes, such as the PTW microDiamond, cannot be caused by the photon and electron interactions within these sensitive layers because they are only a few micrometers thick. The alternative explanation is that their overresponse is caused by the combination of two effects, the modification of the secondary electron fluence profile i) by a field size too small to warrant lateral secondary electron equilibrium and ii) by the density-dependent electron ranges in the structural detector materials placed in front of or backing the sensitive layer...
November 17, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29148120/mapping-brown-adipose-tissue-based-on-fat-water-fraction-provided-by-z-spectral-imaging
#4
Alessandro Scotti, Rong-Wen Tain, Weiguo Li, Victoria Gil, Chong Wee Liew, Kejia Cai
BACKGROUND: Brown adipose tissue (BAT) has a great relevance in metabolic diseases and has been shown to be reduced in obesity and insulin resistance patients. Currently, Dixon MRI is used to calculate fat-water fraction (FWF) and differentiate BAT from white adipose tissue (WAT). However, it may fail in areas of phase wrapping and introduce fat-water swapping artifacts. PURPOSE: To investigate the capacity of the Z-spectrum imaging (ZSI) for the identification of BAT in vivo...
November 17, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/29148102/adaptive-integrated-parallel-reception-excitation-and-shimming-ipres-a-with-microelectromechanical-systems-switches
#5
Dean Darnell, Yixin Ma, Hongyuan Wang, Fraser Robb, Allen W Song, Trong-Kha Truong
PURPOSE: Integrated parallel reception, excitation, and shimming coil arrays with N shim loops per radio-frequency (RF) coil element (iPRES(N)) allow an RF current and N direct currents (DC) to flow in each coil element, enabling simultaneous reception/excitation and shimming of highly localized B0 inhomogeneities. The purpose of this work was to reduce the cost and complexity of this design by reducing the number of DC power supplies required by a factor N, while maintaining a high RF and shimming performance...
November 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29148092/an-inductively-coupled-ultra-thin-flexible-and-passive-rf-resonator-for-mri-marking-and-guiding-purposes-clinical-feasibility
#6
Akbar Alipour, Sayim Gokyar, Oktay Algin, Ergin Atalar, Hilmi Volkan Demir
PURPOSE: The purpose of this study is to develop a wireless, flexible, ultra-thin, and passive radiofrequency-based MRI resonant fiducial marker, and to validate its feasibility in a phantom model and several body regions. METHODS: Standard microfabrication processing was used to fabricate the resonant marker. The proposed marker consists of two metal traces in the shape of a square with an edge length of 8 mm, with upper and lower traces connected to each other by a metalized via...
November 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29145838/mri-characteristics-for-phantom-scratching-in-canine-syringomyelia
#7
Zoe R Nalborczyk, Angus K McFadyen, Jelena Jovanovik, Anna Tauro, Colin J Driver, Noel Fitzpatrick, Susan P Knower, Clare Rusbridge
BACKGROUND: A classic sign of canine syringomyelia (SM) is scratching towards one shoulder. Using magnetic resonance imaging (MRI) we investigate the spinal cord lesion relating to this phenomenon which has characteristics similar to fictive scratch secondary to spinal cord transection. Medical records were searched for Cavalier King Charles spaniels with a clinical and MRI diagnosis of symptomatic SM associated with Chiari-like malformation (CM). The cohort was divided into SM with phantom scratching (19 dogs) and SM but no phantom scratching (18 dogs)...
November 16, 2017: BMC Veterinary Research
https://www.readbyqxmd.com/read/29145179/phantom-sensations-supernumerary-phantom-limbs-and-apotemnophilia-three-body-representation-disorders
#8
Laurent Tatu, Julien Bogousslavsky
Body representation disorders continue to be mysterious and involve the anatomical substrate that underlies the mental representation of the body. These disorders sit on the boundaries of neurological and psychiatric diseases. We present the main characteristics of 3 examples of body representation disorders: phantom sensations, supernumerary phantom limb, and apotemnophilia. The dysfunction of anatomical circuits that regulate body representation can sometimes have paradoxical features. In the case of phantom sensations, the patient feels the painful subjective sensation of the existence of the lost part of the body after amputation, surgery or trauma...
2018: Frontiers of Neurology and Neuroscience
https://www.readbyqxmd.com/read/29144105/motor-imagery-ability-of-patients-with-lower-limb-amputation-exploring-the-course-of-rehabilitation-effects
#9
Elodie Saruco, Aymeric Guillot, Arnaud Saimpont, Franck DI Rienzo, Anne Durand, Catherine Mercier, Francine Malouin, Philip Jackson
BACKGROUND: Amputation of a lower-limb results in a severe decrease of functional mobility that deeply alters independent living. Motor imagery (MI) refers to the mental representation of an action without engaging its actual execution. The repetitive use of MI has been shown to contribute to promote motor recovery and phantom-limb pain alleviation. AIM: Given the importance of invoking accurate images to benefit from MI practice, and considering the link between motor capacities and MI, the present study investigated the effect of a rehabilitation program on MI ability in patients with lower-limb amputation...
November 16, 2017: European Journal of Physical and Rehabilitation Medicine
https://www.readbyqxmd.com/read/29144031/error-analysis-of-helmholtz-based-mr-electrical-properties-tomography
#10
Stefano Mandija, Alessandro Sbrizzi, Ulrich Katscher, Peter R Luijten, Cornelis A T van den Berg
PURPOSE: MR electrical properties tomography (MR-EPT) aims to measure tissue electrical properties by computing spatial derivatives of measured B1+ data. This computation is very sensitive to spatial fluctuations caused, for example, by noise and Gibbs ringing. In this work, the error arising from the computation of spatial derivatives using finite difference kernels (FD error) has been investigated. In relation to this FD error, it has also been investigated whether mitigation strategies such as Gibbs ringing correction and Gaussian apodization can be beneficial for conductivity reconstructions...
November 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29143829/spectral-properties-of-ionic-benzotristhiazole-based-donor-acceptor-nlo-phores-in-polymer-matrices-and-their-one-and-two-photon-cellular-imaging-ability
#11
M Danko, P Hrdlovič, A Martinická, A Benda, M Cigáň
A series of ionic benzotristhiazolium (BTT) push-pull chromophores, with different nitrogen donor groups and different lengths of conjugated bridges, was successfully doped in polar polymer matrices (PVC and PSS). The spectral (photophysical) properties of their low concentration thin polymeric films are compared with those in solution and are discussed in terms of matrix polarity/viscosity influence, specific polymer-chromophore interaction, structure-spectral property relationship and Twisted Intramolecular Charge-Transfer (TICT) state formation...
November 16, 2017: Photochemical & Photobiological Sciences
https://www.readbyqxmd.com/read/29142343/calculating-gamma-camera-uniformity-parameters-beyond-the-vendor-specific-protocol
#12
Anil Kumar Pandey, Param Dev Sharma, Jay Prakash Kumar, Kartik Saroha, Chetan Patel, Chandra Sekhar Bal, Rakesh Kumar
Objectives: The aim of this study was to develop and verify a personal computer-based software tool for calculating uniformity indices of gamma camera. Materials and Methods: The program was developed in MATLAB R2013b under Microsoft Windows operating system. Noise-less digital phantoms with known uniformity parameters were used to verify the accuracy of the program. Two hundred and forty-four Co-57 flood source images were acquired on Symbia T6 and Discovery nuclear medicine/computed tomography 670...
October 2017: Indian Journal of Nuclear Medicine: IJNM: the Official Journal of the Society of Nuclear Medicine, India
https://www.readbyqxmd.com/read/29141630/ct-based-analysis-of-muscle-volume-and-degeneration-of-gluteus-medius-in-patients-with-unilateral-hip-osteoarthritis
#13
Takako Momose, Yutaka Inaba, Hyonmin Choe, Naomi Kobayashi, Taro Tezuka, Tomoyuki Saito
BACKGROUND: The gluteus medius (GMED) affects hip function as an abductor. We evaluated muscle volume and degeneration of the GMED by using CT-based analysis and assessed factors that affect hip abductor strength in patients with unilateral hip osteoarthritis (OA). METHODS: We examined clinical and imaging findings associated with hip abductor strength in consecutive 50 patients with unilateral hip OA. Hip abductor muscle strength and Harris hip score (HHS) were assessed...
November 15, 2017: BMC Musculoskeletal Disorders
https://www.readbyqxmd.com/read/29141450/investigation-of-cerebrospinal-fluid-flow-in-the-cerebral-aqueduct-using-high-resolution-phase-contrast-measurements-at-7t-mri
#14
Karin Markenroth Bloch, Johannes Töger, Freddy Ståhlberg
Background The cerebral aqueduct is a central conduit for cerebrospinal fluid (CSF), and non-invasive quantification of CSF flow in the aqueduct may be an important tool for diagnosis and follow-up of treatment. Magnetic resonance (MR) methods at clinical field strengths are limited by low spatial resolution. Purpose To investigate the feasibility of high-resolution through-plane MR flow measurements (2D-PC) in the cerebral aqueduct at high field strength (7T). Material and Methods 2D-PC measurements in the aqueduct were performed in nine healthy individuals at 7T...
January 1, 2017: Acta Radiologica
https://www.readbyqxmd.com/read/29140576/comparison-between-qualitative-and-quantitative-assessment-of-background-parenchymal-enhancement-on-breast-mri
#15
Akshat C Pujara, Artem Mikheev, Henry Rusinek, Yiming Gao, Chloe Chhor, Kristine Pysarenko, Harikrishna Rallapalli, Jerzy Walczyk, Melanie Moccaldi, James S Babb, Amy N Melsaether
BACKGROUND: Potential clinical implications of the level of background parenchymal enhancement (BPE) on breast MRI are increasing. Currently, BPE is typically evaluated subjectively. Tests of concordance between subjective BPE assessment and computer-assisted quantified BPE have not been reported. PURPOSE OR HYPOTHESIS: To compare subjective radiologist assessment of BPE with objective quantified parenchymal enhancement (QPE). STUDY TYPE: Cross-sectional observational study...
November 15, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/29140328/retina-simulating-phantom-produced-by-photolithography
#16
Denise Valente, Brian Vohnsen
Cone photoreceptors have a narrow acceptance angle that is well matched to the size of the eye pupil and dampens the visual impact of aberrations and scattering. However, the structure of the human retina is not replicated in existing eye models used to test refractive designs or retinal implants that restore partial vision to the blind. Here, we report on an artificial waveguide-based retinal phantom manufactured by photolithography in photoresist film with dimensions and refractive index contrast similar to the retinal receptor layer...
November 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/29139245/evaluation-of-a-pointwise-microcirculation-assessment-method-using-liquid-and-multilayered-tissue-simulating-phantoms
#17
Ingemar Fredriksson, Rolf B Saager, Anthony J Durkin, Tomas Strömberg
A fiber-optic probe-based instrument, designed for assessment of parameters related to microcirculation, red blood cell tissue fraction (fRBC), oxygen saturation (SO2), and speed resolved perfusion, has been evaluated using state-of-the-art tissue phantoms. The probe integrates diffuse reflectance spectroscopy (DRS) at two source-detector separations and laser Doppler flowmetry, using an inverse Monte Carlo method for identifying the parameters of a multilayered tissue model. Here, we characterize the accuracy of the DRS aspect of the instrument using (1) liquid blood phantoms containing yeast and (2) epidermis-dermis mimicking solid-layered phantoms fabricated from polydimethylsiloxane, titanium oxide, hemoglobin, and coffee...
November 2017: Journal of Biomedical Optics
https://www.readbyqxmd.com/read/29139034/vessel-centerline-reconstruction-from-non-isocentric-and-non-orthogonal-paired-monoplane-angiographic-images
#18
Mie Kunio, Caroline C O'Brien, Augusto C Lopes, Lynn Bailey, Pedro A Lemos, Guillermo J Tearney, Elazer R Edelman
PURPOSE: Three-dimensional reconstruction of a vessel centerline from paired planar coronary angiographic images is critical to reconstruct the complex three-dimensional structure of the coronary artery lumen and the relative positioning of implanted devices. In this study, a new vessel centerline reconstruction method that can utilize non-isocentric and non-orthogonal pairs of angiographic images was developed and tested. METHODS: Our new method was developed in in vitro phantom models of bifurcated coronary artery with and without stent, and then tested in in vivo swine models (twelve coronary arteries)...
November 14, 2017: International Journal of Cardiovascular Imaging
https://www.readbyqxmd.com/read/29138489/a-dual-channel-endoscope-for-quantitative-imaging-monitoring-and-triggering-of-doxorubicin-release-from-liposomes-in-living-mice
#19
Jeremy Kress, Daniel J Rohrbach, Kevin A Carter, Dandan Luo, Chien Poon, Semra Aygun-Sunar, Shuai Shao, Shashikant Lele, Jonathan F Lovell, Ulas Sunar
Doxorubicin (Dox) is approved for use in liposomal form for the treatment of ovarian cancer. We previously developed a long-circulating Dox formulation in liposomes containing small amounts of porphyrin-phospholipid, which enables on-demand drug release with near-infrared irradiation. In this study, we present and evaluate a dual-modal, dual-channel light endoscope that allows quantitative reflectance and fluorescence imaging for monitoring of local Dox concentrations in target areas. The endoscope consists of two flexible imaging fibers; one to transmit diagnostic and therapeutic light to the target, and the other to detect fluorescent and reflected light...
November 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29138230/head-to-head-comparison-of-global-and-regional-two-dimensional-speckle-tracking-strain-versus-cardiac-magnetic-resonance-tagging-in-a-multicenter-validation-study
#20
Mihaela Silvia Amzulescu, Hélène Langet, Eric Saloux, Alain Manrique, Laurianne Boileau, Alisson Slimani, Pascal Allain, Clotilde Roy, Christophe de Meester, Agnès Pasquet, Mathieu De Craene, David Vancraeynest, Anne-Catherine Pouleur, Jean-Louis J Vanoverschelde, Bernhard L Gerber
BACKGROUND: Despite widespread use to characterize and refine prognosis, validation data of two-dimensional (2D) speckle tracking (2DST) echocardiography myocardial strain measurement remain scarce. METHODS AND RESULTS: Global and regional subendocardial peak-systolic Lagrangian longitudinal (LS) and circumferential strain (CS) by 2DST and 2D-tagged (2DTagg) cardiac magnetic resonance imaging were compared against sonomicrometry in a dynamic heart phantom and among each other in 136 patients included prospectively at 2 centers...
November 2017: Circulation. Cardiovascular Imaging
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