نتایج جستجو برای: air correction

تعداد نتایج: 368892  

Journal: :Journal of biomedical optics 2015
Tianjie Li Lei Tian Like Wang Ying Hon Andrew K C Lam Yifei Huang Yuanyuan Wang Yongping Zheng

The measurement of central corneal thickness (CCT) is important in ophthalmology. Most studies concerned the value at normal status, while rare ones focused on its dynamic changing. The commercial Corvis ST is the only commercial device currently available to visualize the two-dimensional image of dynamic corneal profiles during an air puff indentation. However, the directly observed CCT involv...

2016
Qiurui He Zhenzhan Wang Jieying He

The Microwave Humidity and Temperature sounder (MWHTS) on board the Fengyun (FY)-3C satellite measure the outgoing radiance form the Earth surface and atmospheric constituents. MWHTS makes measurements in the isolated oxygen absorption line near 118 GHz and the vicinity of strong water vapor line around 183 GHz, can provide fine vertical distribution structure of both atmospheric humidity and t...

2016
Qiurui He Zhenzhan Wang Jieying He Robert W. Talbot

Abstract: The microwave humidity and temperature sounder (MWHTS) on the Fengyun (FY)-3C satellite measures the outgoing radiance from the Earth’s surface and atmospheric constituents. MWHTS, which makes measurements in the isolated oxygen absorption line near 118 GHz and the vicinity of the strong water vapor absorption line around 183 GHz, can provide fine vertical distribution structures of b...

Journal: :Journal of radiation research 2007
Kook Jin Chun Gwang Ho Yoo

Data required for the determination of the absolute air kerma rate for (60)Co and (137)Cs gamma-rays using spherical cavity chambers were calculated using the EGS4 Monte Carlo system. Mass energy-absorption coefficient ratio and the stopping power ratio were calculated for a 10 cm(3) primary standard graphite-walled ionization chamber from the unfolded energy pulse height distributions of (60)C...

2014
Ji-Yung Kwon Chang-Whe Kim Young-Jun Lim Ho-Beom Kwon Myung-Joo Kim

PURPOSE The aim of the present study was to evaluate the accuracy of three techniques for correction of cast implant bars. MATERIALS AND METHODS Thirty cast implant bars were fabricated on a metal master model. All cast implant bars were sectioned at 5 mm from the left gold cylinder using a disk of 0.3 mm thickness, and then each group of ten specimens was corrected by gas-air torch soldering...

Journal: :Medical physics 2004
Hugo Bouchard Jan Seuntjens

The present paper addresses reference dose measurements using thimble ionization chambers for quality assurance in IMRT fields. In these radiation fields, detector fluence perturbation effects invalidate the application of open-field dosimetry protocol data for the derivation of absorbed dose to water from ionization chamber measurements. We define a correction factor C(Q)IMRT to correct the ab...

Journal: :iranian journal of basic medical sciences 0
shabnam oloomi department of medical physics, mashhad university of medical science, mashhad, iran hadi noori eskandari department of applied mathematics, school of mathematical sciences, ferdowsi university of mashhad, mashhad, iran seyed rasoul zakavi nuclear medicine research center, imam reza hospital, faculty of medicine, mashhad university of medical sciences, mashhad, iran peter knoll department of nuclear medicine wilhelminenspital vienna, austria faraz kalantari research center for nuclear medicine, tehran university of medical sciences, tehran, iran mohsen hajizadeh saffar department of medical physics, mashhad university of medical science, mashhad, iran

objective(s): in spect, the sinogram contains scatter and lack of attenuated counts that degrade the reconstructed image quality and quantity. many techniques for attenuation and scatter correction have been proposed. an acceptable method of correction is to incorporate effects into an iterative statistical reconstruction. here, we propose new maximum likelihood expectation maximization (mlem) ...

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