نتایج جستجو برای: noise dose

تعداد نتایج: 502879  

2003
Predrag R. Bakic Michael Albert Andrew D. A. Maidment Thomas Jefferson

Stereoscopic viewing of radiographic images is advantageous in reducing ambiguity due to background anatomic noise. This advantage is usually considered to be balanced by doubling the dose required for acquisition of a stereo image pair. In the case of a quantum-noise limited detector, detection theory suggests a possible decrease of the dose by half. We tested this assumption by a series of co...

Journal: :AJNR. American journal of neuroradiology 2008
M T Russell J R Fink F Rebeles K Kanal M Ramos Y Anzai

BACKGROUND AND PURPOSE The advancement of multidetector CT technology has resulted in improved image quality as well as an increase in ionizing radiation dose to patient. The purpose of this study was to assess radiation dose and overall image quality of CT examination of the neck between fixed-tube current and automatic tube current modulation (ATCM) at 2 separate noise index levels. MATERIA...

Journal: :Physics in medicine and biology 2000
R Jeraj P Keall

The effect of the statistical uncertainty, or noise, in inverse treatment planning for intensity modulated radiotherapy (IMRT) based on Monte Carlo dose calculation was studied. Sets of Monte Carlo beamlets were calculated to give uncertainties at Dmax ranging from 0.2% to 4% for a lung tumour plan. The weights of these beamlets were optimized using a previously described procedure based on a s...

2016
Bjørn Helge Østerås Kristin Livelten Heggen Hans Kristian Pedersen Hilde Kjernlie Andersen Anne Catrine T Martinsen

BACKGROUND Iterative reconstruction can reduce image noise and thereby facilitate dose reduction. PURPOSE To evaluate qualitative and quantitative image quality for full dose and dose reduced head computed tomography (CT) protocols reconstructed using filtered back projection (FBP) and adaptive statistical iterative reconstruction (ASIR). MATERIAL AND METHODS Fourteen patients undergoing fo...

Journal: :J. Electronic Imaging 2015
Amber J. Gislason-Lee Asli Kumcu Stephen M. Kengyelics Laura A. Rhodes Andrew G. Davies

Dynamic X-ray imaging systems are used for interventional cardiac procedures to treat coronary heart disease. X-ray settings are controlled automatically by specially-designed X-ray dose control mechanisms whose role is to ensure an adequate level of image quality is maintained with an acceptable radiation dose to the patient. Current commonplace dose control designs quantify image quality by p...

Journal: :International Journal of Medical Physics, Clinical Engineering and Radiation Oncology 2022

Purpose: Children are sometimes examined with Computed Tomography protocols designed for adults, leading to radiation doses higher than necessary. Lack of optimisation could lead image quality what is needed diagnostic purposes associated high patients. Optimising the paediatric head trauma CT imaging will reduce dose. Objective: The study aimed optimise dose and assess a set by evaluating nois...

Journal: :Journal of nuclear cardiology : official publication of the American Society of Nuclear Cardiology 2012
Andrew J Einstein Carl D Elliston Daniel W Groves Bin Cheng Steven D Wolff Gregory D N Pearson M Robert Peters Lynne L Johnson Sabahat Bokhari Gary W Johnson Ketan Bhatia Theodore Pozniakoff David J Brenner

BACKGROUND Coronary computed tomographic angiography (CCTA) is associated with high radiation dose to the female breasts. Bismuth breast shielding offers the potential to significantly reduce dose to the breasts and nearby organs, but the magnitude of this reduction and its impact on image quality and radiation dose have not been evaluated. METHODS Radiation doses from CCTA to critical organs...

2016
Tatsuya Nishii Atsushi K. Kono Wakiko Tani Erina Suehiro Noriyuki Negi Satoru Takahashi Kazuro Sugimura Ferdinand Frauscher

Backgrounds. This study examines the hypothesis that four-dimensional noise reduction (4DNR) with short interval times reduces noise in cardiac computed tomography (CCT) using "padding" phases. Furthermore, the capability of reducing the reduction dose in CCT using this post-processing technique was assessed. Methods. Using base and quarter radiation doses for CCT (456 and 114 mAs/rot with 120 ...

2014
Dietrich Beitzke Richard Nolz Sylvia Unterhumer Christina Plank Michael Weber Rüdiger Schernthaner Veronika Schöpf Florian Wolf Christian Loewe

OBJECTIVE To prospectively evaluate image quality and radiation dose using a low-dose computed tomography angiography protocol and iterative image reconstruction for high-pitch dual-source CT-angiography (DSCTA) of the supraaortic arteries. MATERIAL AND METHODS DSCTA was performed in 42 patients, using either 120 kVp tube voltage, 120 mAS tube current, 2.4 pitch and filtered back projection, ...

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