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Lawrence Lechuga, Georg A Weidlich
A comparison of image quality and dose delivered between two differing computed tomography (CT) imaging modalities-fan beam and cone beam-was performed. A literature review of quantitative analyses for various image quality aspects such as uniformity, signal-to-noise ratio, artifact presence, spatial resolution, modulation transfer function (MTF), and low contrast resolution was generated. With these aspects quantified, cone beam computed tomography (CBCT) shows a superior spatial resolution to that of fan beam, while fan beam shows a greater ability to produce clear and anatomically correct images with better soft tissue differentiation...
September 12, 2016: Curēus
Samuel J Blake, Zhangkai Cheng, Shaghik Atakaramians, Steven Meikle, Minghui Lu, Philip Vial, Zdenka Kuncic
PURPOSE: A Geant4 model of a novel, water-equivalent electronic portal imaging device (EPID) prototype for radiotherapy imaging and dosimetry utilising an array of plastic scintillating fibres (PSFs) has been developed. Monte Carlo (MC) simulations were performed to quantify the PSF-EPID imaging performance and to investigate design aspects affecting performance for optimisation. METHODS: Using the Geant4 model, the PSF-EPID's imaging performance for 6 MV photon beams was quantified in terms of its modulation transfer function (MTF), noise power spectrum (NPS) and detective quantum efficiency (DQE)...
October 13, 2016: Physica Medica: PM
Rene Seiger, Andreas Hahn, Allan Hummer, Georg S Kranz, Sebastian Ganger, Michael Woletz, Christoph Kraus, Ronald Sladky, Alexander Kautzky, Siegfried Kasper, Christian Windischberger, Rupert Lanzenberger
Sex-steroid hormones are primarily involved in sexual differentiation and development and are thought to underlie processes related to cognition and emotion. However, divergent results have been reported concerning the effects of hormone administration on brain structure including side effects like brain atrophy and dementia. Cross-sex hormone therapy in transgender subjects offers a unique model for studying the effects of sex hormones on the living human brain. In this study, 25 Female-to-Male (FtM) and 14 Male-to-Female (MtF) subjects underwent MRI examinations at baseline and after a period of at least 4-months of continuous cross-sex hormone administration...
October 5, 2016: Psychoneuroendocrinology
Tamar Arens-Arad, Nairouz Farah, Shai Ben-Yaish, Alex Zlotnik, Zeev Zalevsky, Yossi Mandel
Novel technologies are constantly under development for vision restoration in blind patients. Many of these emerging technologies are based on the projection of high intensity light patterns at specific wavelengths, raising the need for the development of specialized projection systems. Here we present and characterize a novel projection system that meets the requirements for artificial retinal stimulation in rats and enables the recording of cortical responses. The system is based on a customized miniature Digital Mirror Device (DMD) for pattern projection, in both visible (525 nm) and NIR (915 nm) wavelengths, and a lens periscope for relaying the pattern directly onto the animal's retina...
October 12, 2016: Scientific Reports
Antonio Sarno, Giovanni Mettivier, Francesca Di Lillo, Mario Cesarelli, Paolo Bifulco, Paolo Russo
We developed a scanner for micro computed tomography dedicated to the breast (BµCT) with a high resolution flat-panel detector and a microfocus X-ray tube. We evaluated the system spatial resolution via the 3D modulation transfer function (MTF). In addition to conventional absorption-based X-ray imaging, such a prototype showed capabilities for propagation-based phase-contrast and related edge enhancement effects in 3D imaging. The system limiting spatial resolution is 6.2mm(-1) (MTF at 10%) in the vertical direction and 3...
October 7, 2016: Medical Engineering & Physics
Carla Busquets-Cortés, Xavier Capó, Miquel Martorell, Josep A Tur, Antoni Sureda, Antoni Pons
Exercise training induces adaptations in mitochondrial metabolism, dynamics, and oxidative protection. Omega-3 fatty acids change membrane lipid composition and modulate mitochondrial function. The aim was to investigate the effect of 8-week training and docosahexaenoic acid (DHA) supplementation (1.14 g/day) on the mitochondria dynamics and antioxidant status in peripheral blood mononuclear cells (PBMCs) from sportsmen. Subjects were assigned to an intervention (N = 9) or placebo groups (N = 7) in a randomized double-blind trial...
2016: Oxidative Medicine and Cellular Longevity
Daniel Carson, Zaiwei Xu, Elsinore Alexander, Myoung Choi, Zeyu Zhao, Xin Hong
PURPOSE: To compare the optical performance of 3 trifocal intraocular lenses (IOLs): the Acrysof IQ Panoptix (+2.17 diopter [D]/+3.25 D IOL), AT LISA Tri 839MP (+1.66 D/+3.33 D IOL), and Finevision Micro F (+1.75 D/+3.50 D IOL). SETTING: Alcon Research Ltd., Fort Worth, Texas, USA. DESIGN: Experimental study. METHODS: The 3 trifocal IOLs were compared using optical performance tests. To measure image quality, through-focus modulation transfer function (MTF) curves were generated for a model eye...
September 2016: Journal of Cataract and Refractive Surgery
Clare Bellhouse, Sandra Walker, Christopher K Fairley, Lenka A Vodstrcil, Catriona S Bradshaw, Marcus Y Chen, Eric P F Chow
OBJECTIVE: Literature surrounding the healthcare needs of transgender individuals is limited in Australia. This study aimed to investigate the demographic characteristics, risk behaviours and HIV/STI positivity among male-to-female (MTF) and female-to-male (FTM) transgender individuals attending Melbourne Sexual Health Centre (MSHC), Australia, between 2011 and 2014. METHOD: A retrospective cohort analysis for 133 transgender individuals was conducted based on the first visit of individuals to MSHC during the study period...
September 29, 2016: Sexually Transmitted Infections
Guang Li, Travis C Greene, Thomas K Nishino, Charles E Willis
The purpose of this study was to evaluate several of the standardized image quality metrics proposed by the American Association of Physics in Medicine (AAPM) Task Group 150. The task group suggested region-of-interest (ROI)-based techniques to measure nonuniformity, minimum signal-to-noise ratio (SNR), number of anomalous pixels, and modulation transfer function (MTF). This study evaluated the effects of ROI size and layout on the image metrics by using four different ROI sets, assessed result uncertainty by repeating measurements, and compared results with two commercially available quality control tools, namely the Carestream DIRECTVIEW Total Quality Tool (TQT) and the GE Healthcare Quality Assurance Process (QAP)...
2016: Journal of Applied Clinical Medical Physics
Maria-Gabriela Garcia, Rudolf Wall, Benjamin Steinhilber, Thomas Läubli, Bernard J Martin
OBJECTIVE: The aim of this study was to evaluate the long-lasting effects of prolonged standing work on a hard floor or floor mat and slow-pace walking on muscle twitch force (MTF) elicited by electrical stimulation. BACKGROUND: Prolonged standing work may alter lower-leg muscle function, which can be quantified by changes in the MTF amplitude and duration related to muscle fatigue. Ergonomic interventions have been proposed to mitigate fatigue and discomfort; however, their influences remain controversial...
September 9, 2016: Human Factors
Azeez Omotayo, Idris Elbakri
OBJECTIVE: Iterative algorithms are gaining clinical acceptance in CT. We performed objective phantom-based image quality evaluation of five commercial iterative reconstruction algorithms available on four different multi-detector CT (MDCT) scanners at different dose levels as well as the conventional filtered back-projection (FBP) reconstruction. METHODS: Using the Catphan500 phantom, we evaluated image noise, contrast-to-noise ratio (CNR), modulation transfer function (MTF) and noise-power spectrum (NPS)...
September 9, 2016: Journal of X-ray Science and Technology
José R Jiménez, Aixa Alarcón, Rosario G Anera, Luis Jiménez Del Barco
PURPOSE: To model the effect of pupil size, optical zone, and initial myopic level on the retinal image quality after Q-optimized myopic corneal refractive surgery. METHODS: Different Q-optimized and paraxial Munnerlyn algorithms were tested using a schematic myopic eye model to analyze the optical quality of the final retinal image for initial myopic errors from -1.00 to -7.00 diopters (D). Different optical zones (5.5, 6, and 6.5 mm in diameter) and two pupil diameters (5 and 7 mm, mesopic-scotopic conditions) were included in the comparison...
August 1, 2016: Journal of Refractive Surgery
Jaclyn M White Hughto, Sari L Reisner
OBJECTIVES: To review evidence from prospective cohort studies of the relationship between hormone therapy and changes in psychological functioning and quality of life in transgender individuals accessing hormone therapy over time. DATA SOURCES: MEDLINE, PsycINFO, and PubMed were searched for relevant studies from inception to November 2014. Reference lists of included studies were hand searched. RESULTS: Three uncontrolled prospective cohort studies, enrolling 247 transgender adults (180 male-to-female [MTF], 67 female-to-male [FTM]) initiating hormone therapy for the treatment of gender identity disorder (prior diagnostic term for gender dysphoria), were identified...
January 2016: Transgend Health
Maribel Bruno, Jeffrey Ross, Yue Ge
Hexavalent chromium (Cr (VI)) is an environmental human carcinogen which primarily targets lungs. Among a variety of toxic mechanisms, disruption of biological pathways via translational and post-translational modifications represents a key mechanism through which Cr (VI) induces cytotoxicity and carcinogenesis. To identify those disruptions which are altered in response to cytotoxic Cr (VI) exposures, we measured and compared cytotoxicity and changes in expression and phosphorylation status of 15 critical biochemical pathway regulators in human BEAS-2B cells exposed for 48h to a non-toxic concentration (0...
August 31, 2016: Toxicology Letters
Soyoung Lee, Guanghua Yan, Philip Bassett, Arun Gopal, Sanjiv Samant
PURPOSE: To investigate the use of local noise power spectrum (NPS) to characterize image noise and wavelet analysis to isolate defective pixels and inter-subpanel flat-fielding artifacts for quantitative quality assurance (QA) of electronic portal imaging devices (EPIDs). METHODS: A total of 93 image sets including custom-made bar-pattern images and open exposure images were collected from four iViewGT a-Si EPID systems over three years. Global quantitative metrics such as modulation transform function (MTF), NPS, and detective quantum efficiency (DQE) were computed for each image set...
September 2016: Medical Physics
Michael F Bode, Nigel Mackman
INTRODUCTION: Mice with a complete absence of tissue factor (TF) die during embryonic development whereas mice with low levels of TF (Low-TF mice) survive to adulthood. Low-TF mice exhibit spontaneous hemorrhage in various organs, including the lung. In contrast, mice can survive without protease-activated receptor (PAR)-4, which is the major thrombin receptor on mouse platelets. We determined the effect of combining a deficiency PAR-4 (primary hemostasis) with a deficiency in TF (secondary hemostasis) on embryonic development and survival of adult mice...
October 2016: Thrombosis Research
Yasuo Takatsu, Tsuyoshi Ueyama, Tosiaki Miyati, Kenichirou Yamamura
The image characteristics in dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) depend on the partial Fourier fraction and contrast medium concentration. These characteristics were assessed and the modulation transfer function (MTF) was calculated by computer simulation. A digital phantom was created from signal intensity data acquired at different contrast medium concentrations on a breast model. The frequency images [created by fast Fourier transform (FFT)] were divided into 512 parts and rearranged to form a new image...
August 26, 2016: Australasian Physical & Engineering Sciences in Medicine
Tomoya Fujie, Masaki Murakami, Eiko Yoshida, Shuji Yasuike, Tomoki Kimura, Yasuyuki Fujiwara, Chika Yamamoto, Toshiyuki Kaji
Vascular endothelial cells cover the luminal surface of blood vessels and contribute to the prevention of vascular disorders such as atherosclerosis. Metallothionein (MT) is a low molecular weight, cysteine-rich, metal-binding, inducible protein, which protects cells from the toxicity of heavy metals and active oxygen species. Endothelial MT is not induced by inorganic zinc. Adequate tools are required to investigate the mechanisms underlying endothelial MT induction. In the present study, we found that an organoantimony compound, tris(pentafluorophenyl)stibane, induces gene expression of MT-1A and MT-2A, which are subisoforms of MT in bovine aortic endothelial cells...
2016: International Journal of Molecular Sciences
Lindsay M Handren, Candice D Donaldson, William D Crano
Adolescent alcohol use has been linked with a multitude of problems and a trajectory predictive of problematic use in adulthood. Thus, targeting factors that enhance early prevention efforts is vital. The current study highlights variables that mitigate or predict alcohol use and heavy episodic drinking. Using Monitoring the Future (MTF) data, multiple path analytic models revealed links between parental involvement and alcohol abstinence and initiation. Parental involvement predicted enhanced self-esteem and less self-derogation and was negatively associated with peer alcohol norms for each MTF grade sampled, with stronger associations for 8th and 10th graders than 12th graders...
October 2016: Prevention Science: the Official Journal of the Society for Prevention Research
Haodong Shi, Huilin Jiang, Xin Zhang, Chao Wang, Tao Liu
Freeform surfaces have the advantage of balancing off-axis aberration. In this paper, based on the framework of nodal aberration theory (NAT) applied to the coaxial system, the third-order astigmatism and coma wave aberration expressions of an off-axis system with Zernike polynomial surfaces are derived. The relationship between the off-axis and surface shape acting on the nodal distributions is revealed. The nodal aberration properties of the off-axis freeform system are analyzed and validated by using full-field displays (FFDs)...
August 20, 2016: Applied Optics
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