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Monte Carlo simulation

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https://www.readbyqxmd.com/read/27914781/incident-air-kerma-to-absorbed-organ-dose-conversion-factors-for-breast-and-lung-in-pa-thorax-radiography-the-effect-of-patient-thickness-and-radiation-quality
#1
A Kelaranta, P Toroi, P Vock
PURPOSE: Converting the measurable quantities to patient organ doses in projection radiography is usually based on a standard-sized patient model and a specific radiation quality, which are likely to differ from the real situation. Large inaccuracies can therefore be obtained in organ doses, because organ doses are dependent on the exposure parameters, exposure geometry and patient anatomy. In this study, the effect of radiation quality and patient thickness on the organ dose conversion factors were determined...
November 30, 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/27914780/a-monte-carlo-analysis-of-breast-screening-randomized-trials
#2
Luis I Zamora, Cristina Forastero, Damián Guirado, Antonio M Lallena
PURPOSE: To analyze breast screening randomized trials with a Monte Carlo simulation tool. METHODS: A simulation tool previously developed to simulate breast screening programmes was adapted for that purpose. The history of women participating in the trials was simulated, including a model for survival after local treatment of invasive cancers. Distributions of time gained due to screening detection against symptomatic detection and the overall screening sensitivity were used as inputs...
November 30, 2016: Physica Medica: PM
https://www.readbyqxmd.com/read/27914421/target-depth-estimation-in-active-sonar-cramer-rao-bounds-for-a-bilinear-sound-speed-profile
#3
Alexis Mours, Cornel Ioana, Jérôme I Mars, Nicolas F Josso, Yves Doisy
This paper develops a localization method to estimate the depth of a target in the context of active sonar, at long ranges. The target depth is tactical information for both strategy and classification purposes. The Cramer-Rao lower bounds for the target position as range and depth are derived for a bilinear profile. The influence of sonar parameters on the standard deviations of the target range and depth are studied. A localization method based on ray back-propagation with a probabilistic approach is then investigated...
September 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/27914405/delphinid-echolocation-click-detection-probability-on-near-seafloor-sensors
#4
Kaitlin E Frasier, Sean M Wiggins, Danielle Harris, Tiago A Marques, Len Thomas, John A Hildebrand
The probability of detecting echolocating delphinids on a near-seafloor sensor was estimated using two Monte Carlo simulation methods. One method estimated the probability of detecting a single click (cue counting); the other estimated the probability of detecting a group of delphinids (group counting). Echolocation click beam pattern and source level assumptions strongly influenced detectability predictions by the cue counting model. Group detectability was also influenced by assumptions about group behaviors...
September 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/27914386/single-sensor-cue-counting-population-density-estimation-average-probability-of-detection-of-broadband-clicks
#5
Elizabeth T Küsel, Martin Siderius, David K Mellinger
Odontocete echolocation clicks have been used as a preferred cue for density estimation using single-sensor data sets, requiring estimation of detection probability as a function of range. Many such clicks can be very broadband in nature, with 10-dB bandwidths of 20-40 kHz or more. Detection distances are not readily obtained from single-sensor data. Here, the average detection probability is estimated in a Monte Carlo simulation using the passive sonar equation along with transmission loss calculations to estimate the signal-to-noise ratio (SNR) of tens of thousands of click realizations...
September 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/27914385/beamforming-pointing-error-of-a-triaxial-velocity-sensor-under-gain-uncertainties
#6
Tsair-Chuan Lin, Kainam Thomas Wong, Macario O Cordel, Joel Paz Ilao
A "triaxial velocity sensor" consists of three uniaxial velocity sensors, which are nominally identical, orthogonally oriented among themselves, and co-centered at one point in space. A triaxial velocity sensor measures the acoustic particle velocity vector, by its three Cartesian components, individually component-by-component, thereby offering azimuth-elevation two-dimensional spatial directivity, despite the physical compactness that comes with the collocation of its three components. This sensing system's azimuth-elevation beam-pattern has been much analyzed in the open literature, but only for an idealized case of the three uniaxial velocity sensors being exactly identical in gain...
September 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/27914323/quantitative-farm-to-fork-human-norovirus-exposure-assessment-of-individually-quick-frozen-raspberries-and-raspberry-puree
#7
L Jacxsens, A Stals, A De Keuckelaere, B Deliens, A Rajkovic, M Uyttendaele
A quantitative human norovirus (NoV) exposure model describing transmission of NoV during pre-harvest, harvest and further processing of soft red fruits exemplified by raspberries is presented. The outcomes of the model demonstrate the presence of NoV in raspberry puree or individual quick frozen (IQF) raspberry fruits and were generated by Monte Carlo simulations by combining GoldSim® and @Risk® software. Input data were collected from scientific literature, observational studies and assumptions. NoV contamination of soft red fruits is assumed to take place at farms by application of contaminated water for pesticides dilution or by berries' pickers shedding NoV...
November 21, 2016: International Journal of Food Microbiology
https://www.readbyqxmd.com/read/27914258/centralised-decentralised-or-hybrid-sanitation-systems-economic-evaluation-under-urban-development-uncertainty-and-phased-expansion
#8
Ivar Roefs, Brendo Meulman, Jan H G Vreeburg, Marc Spiller
Sanitation systems are built to be robust, that is, they are dimensioned to cope with population growth and other variability that occurs throughout their lifetime. It was recently shown that building sanitation systems in phases is more cost effective than one robust design. This phasing can take place by building small autonomous decentralised units that operate closer to the actual demand. Research has shown that variability and uncertainty in urban development does affect the cost effectiveness of this approach...
November 23, 2016: Water Research
https://www.readbyqxmd.com/read/27913943/the-cost-effectiveness-of-interventions-targeting-lifestyle-change-for-the-prevention-of-diabetes-in-a-swedish-primary-care-and-community-based-prevention-program
#9
Anne Neumann, Lars Lindholm, Margareta Norberg, Olaf Schoffer, Stefanie J Klug, Fredrik Norström
BACKGROUND: Policymakers need to know the cost-effectiveness of interventions to prevent type 2 diabetes (T2D). The objective of this study was to estimate the cost-effectiveness of a T2D prevention initiative targeting weight reduction, increased physical activity and healthier diet in persons in pre-diabetic states by comparing a hypothetical intervention versus no intervention in a Swedish setting. METHODS: A Markov model was used to study the cost-effectiveness of a T2D prevention program based on lifestyle change versus a control group where no prevention was applied...
December 2, 2016: European Journal of Health Economics: HEPAC: Health Economics in Prevention and Care
https://www.readbyqxmd.com/read/27910915/locating-the-quantum-critical-point-of-the-bose-hubbard-model-through-singularities-of-simple-observables
#10
Mateusz Łącki, Bogdan Damski, Jakub Zakrzewski
We show that the critical point of the two-dimensional Bose-Hubbard model can be easily found through studies of either on-site atom number fluctuations or the nearest-neighbor two-point correlation function (the expectation value of the tunnelling operator). Our strategy to locate the critical point is based on the observation that the derivatives of these observables with respect to the parameter that drives the superfluid-Mott insulator transition are singular at the critical point in the thermodynamic limit...
December 2, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27910829/optimization-of-photon-beam-energies-in-gold-nanoparticle-enhanced-arc-radiation-therapy-using-monte-carlo-methods
#11
B Koger, C Kirkby
As a recent area of development in radiation therapy, gold nanoparticle (GNP) enhanced radiation therapy has shown potential to increase tumour dose while maintaining acceptable levels of healthy tissue toxicity. In this study, the effect of varying photon beam energy in GNP enhanced arc radiation therapy (GEART) is quantified through the introduction of a dose scoring metric, and GEART is compared to a conventional radiotherapy treatment. The PENELOPE Monte Carlo code was used to model several simple phantoms consisting of a spherical tumour containing GNPs (concentration: 15 mg Au g(-1) tumour, 0...
December 2, 2016: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/27910712/development-of-a-nanogel-formulation-for-transdermal-delivery-of-tenoxicam-a-pharmacokinetic-pharmacodynamic-modeling-approach-for-quantitative-prediction-of-skin-absorption
#12
Mohammed H Elkomy, Shahira F El Menshawe, Hussein M Eid, Ahmed M A Ali
This study investigates potentials of solid lipid nanoparticles (SLN) based gel for transdermal delivery of tenoxicam (TNX) and describes a pharmacokinetics-pharmacodynamics (PK-PD) modeling approach for predicting concentration-time profile in skin. A 2(3) factorial design was adopted to study the effect of formulation factors on SLN properties and determine the optimal formulation. SLN-gel tolerability was investigated using rabbit skin irritation test. Its anti-inflammatory activity was assessed by carrageenan induced rat paw edema test...
December 2, 2016: Drug Development and Industrial Pharmacy
https://www.readbyqxmd.com/read/27910604/response-function-of-single-crystal-synthetic-diamond-detectors-to-1-4-mev-neutrons-for-spectroscopy-of-d-plasmas
#13
M Rebai, L Giacomelli, A Milocco, M Nocente, D Rigamonti, M Tardocchi, F Camera, C Cazzaniga, Z J Chen, T F Du, T S Fan, A Giaz, Z M Hu, T Marchi, X Y Peng, G Gorini
A Single-crystal Diamond (SD) detector prototype was installed at Joint European Torus (JET) in 2013 and the achieved results have shown its spectroscopic capability of measuring 2.5 MeV neutrons from deuterium plasmas. This paper presents measurements of the SD response function to monoenergetic neutrons, which is a key point for the development of a neutron spectrometer based on SDs and compares them with Monte Carlo simulations. The analysis procedure allows for a good reconstruction of the experimental results...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910536/experimental-study-on-the-fluorescence-spectrum-in-the-near-ultraviolet-and-visible-regions-of-a-carbon-dioxide-gas-cerenkov-medium
#14
Xingyin Guan, Huasi Hu, Zhaohui Song, Hetong Han
We investigated the faint fluorescence spectrum of carbon dioxide in the near-ultraviolet and visible regions using an intense relativistic electron beam accelerator with an energy of 0.2-0.3 MeV. Monte Carlo simulations were carried out in advance to maximize the signal-to-noise ratio and a self-normalization pulse experimental layout was designed to overcome the shot-to-shot fluctuations in different pulses of the accelerator. Ultimately, the relative proportion sequences in the near-ultraviolet and visible regions of a carbon dioxide fluorescence spectrum were successfully obtained for the first time...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910454/development-of-fast-neutron-pinhole-camera-using-nuclear-emulsion-for-neutron-emission-profile-measurement-in-kstar
#15
Y Izumi, H Tomita, Y Nakayama, S Hayashi, K Morishima, M Isobe, M S Cheon, K Ogawa, T Nishitani, T Naka, T Nakano, M Nakamura, T Iguchi
We have developed a compact fast neutron camera based on a stack of nuclear emulsion plates and a pinhole collimator. The camera was installed at J-port of Korea superconducting tokamak advanced research at National Fusion Research Institute, Republic of Korea. Fast neutron images agreed better with calculated ones based on Monte Carlo neutron simulation using the uniform distribution of Deuterium-Deuterium (DD) neutron source in a torus of 40 cm radius.
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910390/validation-of-fast-ion-d-alpha-spectrum-measurements-during-east-neutral-beam-heated-plasmas
#16
J Huang, W W Heidbrink, M G von Hellermann, L Stagner, C R Wu, Y M Hou, J F Chang, S Y Ding, Y J Chen, Y B Zhu, Z Jin, Z Xu, W Gao, J F Wang, B Lyu, Q Zang, G Q Zhong, L Hu, B Wan
To investigate the fast ion behavior, a fast ion D-alpha (FIDA) diagnostic system has been installed on EAST. Fast ion features can be inferred from the Doppler shifted spectrum of Balmer-alpha light from energetic hydrogenic atoms. This paper will focus on the validation of FIDA measurements performed using MHD-quiescent discharges in 2015 campaign. Two codes have been applied to calculate the Dα spectrum: one is a Monte Carlo code, Fortran 90 version FIDASIM, and the other is an analytical code, Simulation of Spectra (SOS)...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910376/measurement-and-simulation-of-the-response-function-of-time-of-flight-enhanced-diagnostics-neutron-spectrometer-for-beam-ion-studies-at-east-tokamak
#17
X Y Peng, Z J Chen, X Zhang, T F Du, Z M Hu, L J Ge, Y M Zhang, J Q Sun, G Gorini, M Nocente, M Tardocchi, L Q Hu, G Q Zhong, N Pu, S Y Lin, B N Wan, X Q Li, G H Zhang, J X Chen, T S Fan
The 2.5 MeV TOFED (Time-Of-Flight Enhanced Diagnostics) neutron spectrometer with a double-ring structure has been installed at Experimental Advanced Superconducting Tokamak (EAST) to perform advanced neutron emission spectroscopy diagnosis of deuterium plasmas. This work describes the response function of the TOFED spectrometer, which is evaluated for the fully assembled instrument in its final layout. Results from Monte Carlo simulations and dedicated experiments with pulsed light sources are presented and used to determine properties of light transport from the scintillator...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27910358/a-recoverable-gas-cell-diagnostic-for-the-national-ignition-facility
#18
A Ratkiewicz, L Berzak Hopkins, D L Bleuel, L A Bernstein, K van Bibber, W S Cassata, B L Goldblum, S Siem, C A Velsko, M Wiedeking, C B Yeamans
The high-fluence neutron spectrum produced by the National Ignition Facility (NIF) provides an opportunity to measure the activation of materials by fast-spectrum neutrons. A new large-volume gas-cell diagnostic has been designed and qualified to measure the activation of gaseous substances at the NIF. This in-chamber diagnostic is recoverable, reusable and has been successfully fielded. Data from the qualification of the diagnostic have been used to benchmark an Monte Carlo N-Particle Transport Code simulation describing the downscattered neutron spectrum seen by the gas cell...
November 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27908188/polymer-gel-dosimetry-for-measuring-the-dose-near-thin-high-z-materials-irradiated-with-high-energy-photon-beams
#19
Leighton L Warmington, N Gopishankar, John H Broadhurst, Yoichi Watanabe
PURPOSE: To investigate the feasibility of three-dimensional (3D) dose measurements near thin high-Z materials placed in a water-like medium by using a polymer gel dosimeter (PGD) when the medium was irradiated with high energy photon beams. METHODS: PGD is potentially a useful tool for this application because it can record the dose around a small object made of a high-Z material in a continuous 3D medium. In this study, the authors manufactured a methacrylic acid-based normoxic PGD, nMAG...
December 2016: Medical Physics
https://www.readbyqxmd.com/read/27908179/an-evaluation-of-spatial-resolution-of-a-prototype-proton-ct-scanner
#20
Tia E Plautz, V Bashkirov, V Giacometti, R F Hurley, R P Johnson, P Piersimoni, H F-W Sadrozinski, R W Schulte, A Zatserklyaniy
PURPOSE: To evaluate the spatial resolution of proton CT using both a prototype proton CT scanner and Monte Carlo simulations. METHODS: A custom cylindrical edge phantom containing twelve tissue-equivalent inserts with four different compositions at varying radial displacements from the axis of rotation was developed for measuring the modulation transfer function (MTF) of a prototype proton CT scanner. Two scans of the phantom, centered on the axis of rotation, were obtained with a 200 MeV, low-intensity proton beam: one scan with steps of 4°, and one scan with the phantom continuously rotating...
December 2016: Medical Physics
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