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https://www.readbyqxmd.com/read/28092636/an-analysis-of-intrinsic-variations-of-low-frequency-shear-wave-speed-in-a-stochastic-tissue-model-the-first-application-for-staging-liver-fibrosis
#1
Yu Wang, Min Wang, Jingfeng Jiang
Shear wave elastography is increasingly being used to non-invasively stage liver fibrosis by measuring shear wave speed (SWS). This study quantitatively investigates intrinsic variations among SWS measurements obtained from heterogeneous media such as fibrotic livers. More specifically, it aims to demonstrate that intrinsic variations in SWS measurements, in general, follow a non-Gaussian distribution and are related to the heterogeneous nature of the medium being measured. Using the principle of maximum entropy (ME), our primary objective is to derive a probability density function (PDF) of the SWS distribution in conjunction with a lossless stochastic tissue model...
February 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28089772/anxiety-like-behavior-due-to-perinatal-exposure-to-bisphenol-a-is-associated-with-decrease-in-excitatory-to-inhibitory-synaptic-density-of-male-mouse-brain
#2
Dhiraj Kumar, M K Thakur
Bisphenol-A (BPA) is a synthetic endocrine disruptor which causes anxiety like behavior in rodents, though the underlying mechanism is not clearly understood. As excitatory-inhibitory synaptic proteins are the key regulators of anxiety, we have examined the effect of perinatal exposure to BPA on this behavior and the expression of excitatory (PSD95), inhibitory (gephyrin) and presynaptic density marker (synaptophysin) proteins in cerebral cortex and hippocampus of 3 and 8 weeks postnatal male mice. In open field (OF) test, BPA exposure reduced the time spent, number of entries and distance travelled in the central zone as compared to control in 8 weeks mice...
January 13, 2017: Toxicology
https://www.readbyqxmd.com/read/28078485/a-simple-method-for-improving-the-spatial-resolution-in-infrared-laser-ablation-mass-spectrometry-imaging
#3
Juha-Pekka Hieta, Anu Vaikkinen, Samuli Auno, Heikki Räikkönen, Markus Haapala, Gianmario Scotti, Jaakko Kopra, Petteri Piepponen, Tiina J Kauppila
In mass spectrometry imaging of tissues, the size of structures that can be distinguished is determined by the spatial resolution of the imaging technique. Here, the spatial resolution of IR laser ablation is markedly improved by increasing the distance between the laser and the focusing lens. As the distance between the laser and the lens is increased from 1 to 18 m, the ablation spot size decreases from 440 to 44 μm. This way, only the collimated center of the divergent laser beam is directed on the focusing lens, which results in better focusing of the beam...
January 11, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28072806/endoscopic-spine-surgery-distance-patients-will-travel-for-minimally-invasive-spine-surgery
#4
Albert E Telfeian, Menno Iprenburg, Ralf Wagner
BACKGROUND: Transforaminal lumbar endoscopic discectomy is a minimally invasive spine surgery procedure performed principally for the treatment of lumbar herniated discs. Endoscopic spine surgeons around the world have noted how far patients will travel to undergo this minimally invasive spine surgery, but the actual distance patients travel has never been investigated. OBJECTIVE: We present here our analysis of how far patients will travel for endoscopic spine surgery by studying the referral patterns of patients to 3 centers in 3 different countries...
January 2017: Pain Physician
https://www.readbyqxmd.com/read/28071852/environmental-and-excitation-power-effects-on-the-ratiometric-upconversion-luminescence-based-temperature-sensing-using-nanocrystalline-nayf4-yb3-er3
#5
Iko Hyppänen, Niina Perälä, Riikka Arppe, Michael Schäferling, Tero Soukka
The luminescence intensity ratio (LIR) of the green emissions of the near-infrared excited NaYF4:Yb3+,Er3+ nanocrystals is a promising method for temperature sensing. Here, the influence of excitation power density, excitation pulse length, excitation wavelength, silica shell, and solvent on the LIR and its temperature response is reported. Primary objective is to study the LIR mechanism and the impact of measurement and environmental parameters on the calibration and precision of the LIR. The LIR value is demonstrated to be unaffected by the excitation intensity in the studied range...
January 10, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28068753/retrospective-matched-pair-cohort-study-on-effect-of-bisegmental-fenestration-versus-hemilaminectomy-for-bisegmental-spinal-canal-stenosis-at-l3-l4-and-l4-l5
#6
Julia Schüppel, Friedrich Weber
Background The main symptoms of degenerative lumbar spinal canal stenosis are progressive back pain, spinal claudication, and, occasionally, sensory and motor deficits. Impairments particularly occur during walking, standing, and sitting. Thus social and vocational activities are increasingly restricted, causing considerable suffering for patients. Surgical therapies are superior to conservative ones. This article studies the outcome of 2-level fenestration versus hemilaminectomy for bisegmental spinal stenosis decompression...
January 9, 2017: Journal of Neurological Surgery. Part A, Central European Neurosurgery
https://www.readbyqxmd.com/read/28067089/metabolomic-applications-in-radiation-biodosimetry-exploring-radiation-effects-through-small-molecules
#7
Evan L Pannkuk, Albert J Fornace, Evagelia C Laiakis
PURPOSE: Exposure of the general population to ionizing radiation has increased in the past decades, primarily due to long distance travel and medical procedures. On the other hand, accidental exposures, nuclear accidents, and elevated threats of terrorism with the potential detonation of a radiological dispersal device or improvised nuclear device in a major city, all have led to increased needs for rapid biodosimetry and assessment of exposure to different radiation qualities and scenarios...
January 9, 2017: International Journal of Radiation Biology
https://www.readbyqxmd.com/read/28060226/barriers-to-care-and-1-year-mortality-among-newly-diagnosed-hiv-infected-people-in-durban-south-africa
#8
Ingrid V Bassett, Sharon M Coleman, Janet Giddy, MFamMed, Laura M Bogart, Christine E Chaisson, Douglas Ross, Moses J E Flash, Tessa Govender, Rochelle P Walensky, Kenneth A Freedberg, Elena Losina
BACKGROUND: Prompt entry into HIV care is often hindered by personal and structural barriers. Our objective was to evaluate the impact of self-perceived barriers to healthcare on 1-year mortality among newly diagnosed HIV-infected individuals in Durban, South Africa. METHODS: Prior to HIV testing at four outpatient sites, adults (≥18y) were surveyed regarding perceived barriers to care including: 1) service delivery; 2) financial; 3) personal health perception; 4) logistical; and 5) structural...
December 30, 2016: Journal of Acquired Immune Deficiency Syndromes: JAIDS
https://www.readbyqxmd.com/read/28059283/modified-optical-fiber-daylighting-system-with-sunlight-transportation-in-free-space
#9
Ngoc-Hai Vu, Thanh-Tuan Pham, Seoyong Shin
We present the design, optical simulation, and experiment of a modified optical fiber daylighting system (M-OFDS) for indoor lighting. The M-OFDS is comprised of three sub-systems: concentration, collimation, and distribution. The concentration part is formed by coupling a Fresnel lens with a large-core plastic optical fiber. The sunlight collected by the concentration sub-system is propagated in a plastic optical fiber and then collimated by the collimator, which is a combination of a parabolic mirror and a convex lens...
December 26, 2016: Optics Express
https://www.readbyqxmd.com/read/28054829/patterns-of-community-participation-across-the-seasons-a-year-long-case-study-of-three-canadian-wheelchair-users
#10
Jacquie Ripat, Jaimie F Borisoff, Lea E Grant, Franco H N Chan
PURPOSE: The aim of this study was to explore the patterns of wheelchair users' community participation across a one-year period, including periods with substantial differences in weather conditions. We sought to develop a detailed understanding of the patterns of, and influences on, wheelchair use and participation within wheelchair users' own communities. METHOD: We conducted an instrumental case study of three purposefully selected individuals who use a wheelchair...
January 5, 2017: Disability and Rehabilitation
https://www.readbyqxmd.com/read/28049356/pushing-stones-uphill-why-patients-are-lost-to-follow-up-after-uncomplicated-ureteroscopy
#11
Nathan A Brooks, Charles J Paul, George M Ghareeb, Chad Robert Tracy
INTRODUCTION: We sought to determine the rate of and factors associated with patient non-adherence to prescribed follow-up after uncomplicated ureteroscopy. METHODS: The records of 247 consecutive patients who underwent ureteroscopy at a tertiary referral center from November 2010 to February 2016 were reviewed. Bivariate and Multivariate analysis was performed to determine the impact of demographic, procedural, socioeconomic, and environmental factors on the rate of compliance with secondary prevention counseling...
January 3, 2017: Journal of Endourology
https://www.readbyqxmd.com/read/28048285/su-g-tep1-12-random-repainting-as-mitigation-for-scanned-ion-beam-interplay-effects
#12
M Bach, J Wulff
PURPOSE: Interference of dose application in scanned beam particle therapy and organ motion may lead to interplay effects with distorted dose to target volumes. Interplay effects depend on the speed and direction of the scanning beam, leading to fringed field edges (scanning parallel to organ motion direction) or over- and under-dosed regions (both directions are orthogonal). Current repainting methods can mitigate interplay effects, but are susceptible to artefacts when only a limited number of repaints are applied...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047792/su-c-206-01-impact-of-charge-sharing-effect-on-sub-pitch-resolution-for-czt-based-photon-counting-ct-systems
#13
X Zheng, Z Cheng, J Deen, H Peng, L Xing
PURPOSES: Photon counting CT is a new imaging technology that can provide tissue composition information such as calcium/iodine content quantification. Cadmium zinc telluride CZT is considered a good candidate the photon counting CT due to its relatively high atomic number and band gap. One potential challenge is the degradation of both spatial and energy resolution as the fine electrode pitch is deployed (<50 µm). We investigated the extent of charge sharing effect as functions of gap width, bias voltage and depth-of-interaction (DOI)...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047289/tu-ab-bra-11-indications-for-online-adaptive-radiotherapy-based-on-dosimetric-consequences-of-interfractional-pancreas-to-duodenum-motion-in-mri-guided-pancreatic-radiotherapy
#14
K Mittauer, S Rosenberg, M Geurts, M Bassetti, I Chen, L Henke, J Olsen, R Kashani, A Wojcieszynski, P Harari, Z Labby, P Hill, B Paliwal, P Parikh, J Bayouth
PURPOSE: Dose limiting structures, such as the duodenum, render the treatment of pancreatic cancer challenging. In this multi-institutional study, we assess dosimetric differences caused by interfraction pancreas-to-duodenum motion using MR-IGRT to determine the potential impact of adaptive replanning. METHODS: Ten patients from two institutions undergoing MRI-guided radiotherapy with conventional fractionation (n=5) or SBRT (n=5) for pancreatic cancer were included...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047134/th-cd-202-11-implications-for-online-adaptive-and-non-adaptive-radiotherapy-of-gastic-and-gastroesophageal-junction-cancers-using-mri-guided-radiotherapy
#15
K Mittauer, M Geurts, R Toya, M Bassetti, P Harari, B Paliwal, J Bayouth
PURPOSE: Radiotherapy for gastric and gastroesophageal junction (GEJ) tumors commonly requires large margins due to deformation, motion and variable changes of the stomach anatomy, at the risk of increased normal tissue toxicities. This work quantifies the interfraction variation of stomach deformation from daily MRI-guided radiotherapy to allow for a more targeted determination of margin expansion in the treatment of gastric and GEJ tumors. METHODS: Five patients treated for gastric (n=3) and gastroesophageal junction (n=2) cancers with conventionally fractionated radiotherapy underwent daily MR imaging on a clinical MR-IGRT system...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047098/su-f-t-457-a-filmless-method-for-measurement-of-couch-translation-per-gantry-rotation-and-couch-speed-for-tomotherapy-using-arccheck
#16
B Yang, R Wong, H Geng, W Lam, K Cheung, S Yu
PURPOSE: To develop a filmless methodology based on an ArcCheck for QA measurement of the couch translation per gantry rotation and couch speed of a Tomotherapy unit. METHODS: Two test plans recommended by TG148 were chosen for this study. A helical plan with 1 cm field size opened the leaves for 180 degrees at the 2nd, 7th and 12th of total 13 rotations and was used to verify if the couch travelled the expected distance per gantry rotation. The other test plan was a static plan with the gantry at 0°, 1cm field width and constant couch movement speed of 0...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047016/th-cd-201-02-a-monte-carlo-investigation-of-a-novel-detector-arrangement-for-the-energy-spectrum-measurement-of-a-6mv-linear-accelerator
#17
S Taneja, L Bartol, W Culberson, L DeWerd
PURPOSE: Direct measurement of the energy spectrum of a 6MV linear accelerator has not been successful due to the high fluence rate, high energy nature of these photon beams. Previous work used a Compton Scattering (CS) spectrometry setup with a shielded spectrometer for spectrum measurements. Despite substantial lead shielding, excessive pulse pile-up was seen. MCNP6 transport code was used to investigate the feasibility and effectiveness of performing measurements using a novel detector setup...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28045777/capillary-flow-rates-in-the-duodenum-of-pediatric-ulcerative-colitis-patients-are-increased-and-unrelated-to-inflammation
#18
Deenaz Zaidi, Lucas Churchill, Hien Q Huynh, Matthew W Carroll, Rabin Persad, Eytan Wine
BACKGROUND: Inflammatory bowel diseases (IBD), including Crohn disease (CD) and ulcerative colitis (UC), are chronic pediatric disorders. Changes in vasculature are described in IBD but these could be secondary to inflammation and the role in pathogenesis is poorly understood. Assessing circulatory changes in typically unaffected sites in IBD (e.g., duodenum), when inflammation is absent, can identify vascular changes associated with pathogenesis. AIM: To measure capillary flow rates in duodenal mucosa using probe-based confocal laser endomicroscopy (pCLE) during endoscopy in children with IBD...
December 30, 2016: Journal of Pediatric Gastroenterology and Nutrition
https://www.readbyqxmd.com/read/28044341/filmless-methods-for-quality-assurance-of-tomotherapy-using-arccheck
#19
B Yang, W K R Wong, H Geng, W W Lam, Y W Ho, W M Kwok, K Y Cheung, S K Yu
PURPOSE: Tomotherapy delivers an intensity-modulated radiation therapy (IMRT) treatment by the synchronization of gantry rotation, multileaf collimator (MLC), and couch movement. This dynamic nature makes the quality assurance (QA) important and challenging. The purpose of this study is to develop some methodologies using an ArcCHECK for accurate QA measurements of the gantry angle and speed, MLC synchronization and leaf open time, couch translation per gantry rotation, couch speed and uniformity, and constancy of longitudinal beam profile for a Tomotherapy unit...
November 21, 2016: Medical Physics
https://www.readbyqxmd.com/read/28042639/the-saudi-clinical-practice-guideline-for-the-prophylaxis-of-venous-thromboembolism-in-long-distance-travelers
#20
Fahad M Al-Hameed, Hasan M Al-Dorzi, Mohamed A Abdelaal, Ali Alaklabi, Ebtisam Bakhsh, Yousef A Alomi, Mohammad Al Baik, Salah Aldahan, Holger Schünemann, Jan Brozek, Wojtek Wiercioch, Andrea J Darzi, Reem Waziry, Elie A Akl
Venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE), is a preventable disease. Long distant travelers are prone to variable degree to develop VTE. However, the low risk of developing VTE among long-distance travelers and which travelers should receive VTE prophylaxis, and what prophylactic measures should be used led us to develop these guidelines. These clinical practice guidelines are the result of an initiative of the Ministry of Health of the Kingdom of Saudi Arabia involving an expert panel led by the Saudi Association for Venous Thrombo Embolism (a subsidiary of the Saudi Thoracic Society)...
January 2017: Saudi Medical Journal
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