Results 211 to 220 of about 83,931 (261)

Test Reliability and Correction for Attenuation

Psychometrika, 1950
Evidence is cited to show that specificity, or lack of equivalence, in the comparable forms of tests has a tendency to lower the value of reliability coefficients but has no tendency to lower the value of observed trait coefficients. This implies that the greater the lack of equivalence, the higher will be coefficients corrected for attenuation. Errors
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Corrections to the attenuation constants of piston attenuators

Proceedings of the IEE - Part III: Radio and Communication Engineering, 1949
The modes existing in a circular waveguide with walls of finite conductivity are investigated and expressions derived for the corrections to the attenuation constant of a piston attenuator. The correction is negligible for E-modes but may be of importance in work of the highest accuracy when H-modes are used.
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SPECT Attenuation Correction

2015
Abstract Attenuation correction minimizes the impact of body habitus on the acquired myocardial count distribution. The superior diagnostic performance of corrected over uncorrected SPECT images is due to improved specificity and normalcy rate.
Fabio Peroba Esteves, James R. Galt
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Segmented attenuation correction for myocardial SPECT

Annals of Nuclear Medicine, 2004
One of the main factors contributing to the accuracy of attenuation correction for SPECT imaging using transmission computed tomography (TCT) with an external gamma-ray source is the radionuclide count. To reduce deterioration of TCT images due to inadequate radionuclide counts, a correction method, segmented attenuation correction (SAC), in which TCT ...
Yasuyuki, Takahashi, Kenya, Murase, Teruhito, Mochizuki, Hiroshi, Higashino, Yoshifumi, Sugawara, Akiyoshi, Kinda   +5 more
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Attenuation corrected cardiac perfusion SPECT

Current Opinion in Cardiology, 2000
Image artifacts, especially those caused by photon attenuation, commonly affect the specificity of cardiac SPECT perfusion imaging. Although often suspected by characteristic patterns identified in female and male patients respectively, the widely variable body habitus of individual patients are associated with unpredictable variations in tissue ...
J R, Corbett, E P, Ficaro
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Adjustments to the correction for attenuation.

Psychological Methods, 2006
With respect to the often-present covariance between error terms of correlated variables, D. W. Zimmerman and R. H. Williams's (1977) adjusted correction for attenuation estimates the strength of the pairwise correlation between true scores without assuming independence of error scores.
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Comparative Accuracy of CT Attenuation-Corrected and Non–Attenuation-Corrected SPECT Myocardial Perfusion Imaging

Clinical Nuclear Medicine, 2012
The aim of the present study was to evaluate whether computed tomography based-attenuation correction (CT-AC) provides any advantage over non-attenuation-corrected (NAC) images for qualitative and quantitative analysis of single photon emission tomography (SPECT) myocardial perfusion imaging (MPI).We retrospectively evaluated data of 171 patients who ...
Punit, Sharma, Chetan D, Patel, Sellam, Karunanithi, Sagar, Maharjan, Arun, Malhotra   +4 more
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Corrections for Attenuation

Educational and Psychological Measurement, 1972
Charles E. Werts, Robert L. Linn
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Tomographic imaging of attenuation with simulation correction for refraction

Ultrasonic Imaging, 1980
Beam refraction in soft tissue and phase cancellation at the receiver can cause large errors and prevent tomographic reconstruction of attenuation. The method developed in this study incorporates simulation of ultrasound propagation into tomographic imaging to correct these effects.
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Correction for Attenuation

2022
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