We consider noise in computed tomography images that are reconstructed using the classical direct fan-beam filtered backprojection algorithm, from both fulland short-scan data. A new, accurate method for computing image covariance is presented. The utility of the new covariance method is demonstrated by its application to the implementation of a channelized Hotelling observer for a lesion detec...

BACKGROUND Reduced image quality from increased X-ray scatter and image noise can be problematic when coronary computed tomography angiography (CCTA) imaging is performed in obese patients. The aim of this study was to compare the image quality and radiation dose obtained using automatic tube potential selection with tube current modulation (APSCM) with those obtained using a body mass index (B...

PURPOSE To retrospectively determine whether the combined use of automatic tube voltage selection (ATVS) and automatic tube current modulation (ATCM) can effectively reduce radiation dose at contrast material-enhanced liver computed tomography (CT) while maintaining acceptable image quality compared with the use of ATCM alone. MATERIALS AND METHODS This study was approved by an institutional ...

OBJECTIVES To compare the effectiveness of two different patient size metrics based on water equivalent diameter (Dw ), the mid-scan water equivalent diameter Dw_c , and the mean (average) water equivalent diameter in the imaged region, Dw_ave , for automatic detection of accidental changes in computed tomography (CT) acquisition protocols. METHODS Patient biometric data (height and weight) w...

Automatic tube current modulation techniques are used in CT to provide predictable image noise in response to variation in patient size. It has been reported that inappropriate centering of the patient in the CT gantry influences the operation of the current modulation, due to greater magnification of body size when the patient is positioned closer to the tube during the acquisition of a fronta...

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...