The Experts below are selected from a list of 36207 Experts worldwide ranked by ideXlab platform
Z.c. Wang - One of the best experts on this subject based on the ideXlab platform.
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Experimental study and optimization of scan parameters that influence radiation dose in temporal bone high-resolution multidetector row CT.
AJNR. American journal of neuroradiology, 2011Co-Authors: Y.t. Niu, Mark E. Olszewski, Y.x. Zhang, Y.f. Liu, J.f. Xian, Z.c. WangAbstract:BACKGROUND AND PURPOSE: MDCT has some specific scan parameters that may systematically increase or decrease radiation dose to patients. This study explored the scan protocol parameters that impact radiation dose in temporal bone MDCT and determined the optimal scan parameters that balance radiation dose with diagnostic image quality. MATERIALS AND METHODS: Using exsomatized cadaveric heads, traditional axial scanning, and helical scanning were performed with different detector Collimations. Helical scans of the same scan region were then acquired by using the determined optimal detector Collimation and various tube voltages, whereas other scan parameters remained fixed. Next, the scans were repeated by using various tube current-time products by using the determined optimal tube voltage. Last, with fixed tube current-time product, the scans were repeated with various pitches. All thin-section, helically acquired scans were reformatted to axial and coronal images with respect to the relevant scanning baseline. In each of the image volumes, the mean and SD HU values in regions of interest were measured in the central section of the internal auditory canal, and CNR values were calculated. RESULTS: In agreement with theory, wider detector Collimations such as 16 × 0.625 mm and 64 × 0.625 mm were associated with lower radiation doses than narrower Collimations due to their lower overbeaming and higher geometric efficiency. In helical scanning, the detector Collimation of 16 × 0.625 mm had higher image quality and the minimum DLP. Axial and coronal images acquired by using a 140-kVp tube voltage had significantly lower noise than scans acquired at 120 or 80 kVp with equivalent volume CT dose index. Diagnostic image quality was achieved when using a minimum tube current-time product of 120 mAs. Noise, CNR, and dose were jointly optimized with a pitch of 0.685. CONCLUSIONS: Temporal bone CT scanning parameters may be optimized by following a systematic procedure that allows for the optimization of diagnostic image quality and the minimization of radiation dose. One such procedure for a particular 64-section MDCT scanner has been presented.
Chee K Saw - One of the best experts on this subject based on the ideXlab platform.
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helical ct of urinary calculi effect of stone composition stone size and scan Collimation
American Journal of Roentgenology, 2000Co-Authors: Chee K Saw, James A Mcateer, Ashish G Monga, Gonzalo T Chua, James E Lingeman, James C WilliamsAbstract:OBJECTIVE. Helical CT has become the preferred methodology for identifying urinary calculi. However, the ability to predict stone composition, which influences patient treatment, depends on the accurate measurement of the radiographic attenuation of stones. We studied the effects of stone composition, stone size, and scan Collimation width on the measurement of attenuation in vitro.MATERIALS AND METHODS. One hundred twenty-seven human urinary calculi of known composition and size were scanned at 120 kVp, 240 mA, and a 1:1 pitch at different Collimations. A model, based on the physics of helical CT, was used to predict the effect of scan Collimation width and stone size on measured attenuation.RESULTS. At a 1-mm Collimation, stone groups could be differentiated by attenuation: the attenuation of uric acid was less than that of cystine or struvite, which overlapped; these were less than the attenuation of calcium oxalate monohydrate, which was in turn lower than that of brushite and hydroxyapatite, which ov...
James C Williams - One of the best experts on this subject based on the ideXlab platform.
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helical ct of urinary calculi effect of stone composition stone size and scan Collimation
American Journal of Roentgenology, 2000Co-Authors: Chee K Saw, James A Mcateer, Ashish G Monga, Gonzalo T Chua, James E Lingeman, James C WilliamsAbstract:OBJECTIVE. Helical CT has become the preferred methodology for identifying urinary calculi. However, the ability to predict stone composition, which influences patient treatment, depends on the accurate measurement of the radiographic attenuation of stones. We studied the effects of stone composition, stone size, and scan Collimation width on the measurement of attenuation in vitro.MATERIALS AND METHODS. One hundred twenty-seven human urinary calculi of known composition and size were scanned at 120 kVp, 240 mA, and a 1:1 pitch at different Collimations. A model, based on the physics of helical CT, was used to predict the effect of scan Collimation width and stone size on measured attenuation.RESULTS. At a 1-mm Collimation, stone groups could be differentiated by attenuation: the attenuation of uric acid was less than that of cystine or struvite, which overlapped; these were less than the attenuation of calcium oxalate monohydrate, which was in turn lower than that of brushite and hydroxyapatite, which ov...
Y.t. Niu - One of the best experts on this subject based on the ideXlab platform.
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Experimental study and optimization of scan parameters that influence radiation dose in temporal bone high-resolution multidetector row CT.
AJNR. American journal of neuroradiology, 2011Co-Authors: Y.t. Niu, Mark E. Olszewski, Y.x. Zhang, Y.f. Liu, J.f. Xian, Z.c. WangAbstract:BACKGROUND AND PURPOSE: MDCT has some specific scan parameters that may systematically increase or decrease radiation dose to patients. This study explored the scan protocol parameters that impact radiation dose in temporal bone MDCT and determined the optimal scan parameters that balance radiation dose with diagnostic image quality. MATERIALS AND METHODS: Using exsomatized cadaveric heads, traditional axial scanning, and helical scanning were performed with different detector Collimations. Helical scans of the same scan region were then acquired by using the determined optimal detector Collimation and various tube voltages, whereas other scan parameters remained fixed. Next, the scans were repeated by using various tube current-time products by using the determined optimal tube voltage. Last, with fixed tube current-time product, the scans were repeated with various pitches. All thin-section, helically acquired scans were reformatted to axial and coronal images with respect to the relevant scanning baseline. In each of the image volumes, the mean and SD HU values in regions of interest were measured in the central section of the internal auditory canal, and CNR values were calculated. RESULTS: In agreement with theory, wider detector Collimations such as 16 × 0.625 mm and 64 × 0.625 mm were associated with lower radiation doses than narrower Collimations due to their lower overbeaming and higher geometric efficiency. In helical scanning, the detector Collimation of 16 × 0.625 mm had higher image quality and the minimum DLP. Axial and coronal images acquired by using a 140-kVp tube voltage had significantly lower noise than scans acquired at 120 or 80 kVp with equivalent volume CT dose index. Diagnostic image quality was achieved when using a minimum tube current-time product of 120 mAs. Noise, CNR, and dose were jointly optimized with a pitch of 0.685. CONCLUSIONS: Temporal bone CT scanning parameters may be optimized by following a systematic procedure that allows for the optimization of diagnostic image quality and the minimization of radiation dose. One such procedure for a particular 64-section MDCT scanner has been presented.
Y.x. Zhang - One of the best experts on this subject based on the ideXlab platform.
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Experimental study and optimization of scan parameters that influence radiation dose in temporal bone high-resolution multidetector row CT.
AJNR. American journal of neuroradiology, 2011Co-Authors: Y.t. Niu, Mark E. Olszewski, Y.x. Zhang, Y.f. Liu, J.f. Xian, Z.c. WangAbstract:BACKGROUND AND PURPOSE: MDCT has some specific scan parameters that may systematically increase or decrease radiation dose to patients. This study explored the scan protocol parameters that impact radiation dose in temporal bone MDCT and determined the optimal scan parameters that balance radiation dose with diagnostic image quality. MATERIALS AND METHODS: Using exsomatized cadaveric heads, traditional axial scanning, and helical scanning were performed with different detector Collimations. Helical scans of the same scan region were then acquired by using the determined optimal detector Collimation and various tube voltages, whereas other scan parameters remained fixed. Next, the scans were repeated by using various tube current-time products by using the determined optimal tube voltage. Last, with fixed tube current-time product, the scans were repeated with various pitches. All thin-section, helically acquired scans were reformatted to axial and coronal images with respect to the relevant scanning baseline. In each of the image volumes, the mean and SD HU values in regions of interest were measured in the central section of the internal auditory canal, and CNR values were calculated. RESULTS: In agreement with theory, wider detector Collimations such as 16 × 0.625 mm and 64 × 0.625 mm were associated with lower radiation doses than narrower Collimations due to their lower overbeaming and higher geometric efficiency. In helical scanning, the detector Collimation of 16 × 0.625 mm had higher image quality and the minimum DLP. Axial and coronal images acquired by using a 140-kVp tube voltage had significantly lower noise than scans acquired at 120 or 80 kVp with equivalent volume CT dose index. Diagnostic image quality was achieved when using a minimum tube current-time product of 120 mAs. Noise, CNR, and dose were jointly optimized with a pitch of 0.685. CONCLUSIONS: Temporal bone CT scanning parameters may be optimized by following a systematic procedure that allows for the optimization of diagnostic image quality and the minimization of radiation dose. One such procedure for a particular 64-section MDCT scanner has been presented.