Objective To evaluate the image quality （IQ） and radiation dose of 128-slice dual-source computed tomography （DSCT） coronary angiography using prospectively electrocardiogram （ECG）-triggered sequen- tial scan mo...Objective To evaluate the image quality （IQ） and radiation dose of 128-slice dual-source computed tomography （DSCT） coronary angiography using prospectively electrocardiogram （ECG）-triggered sequen- tial scan mode compared with ECG-gated spiral scan mode in a population with atrial fibrillation. Methods Thirty-two patients with suspected coronary artery disease and permanent atrial fibrilla- tion referred for a second-generation 128-slice DSCT coronary angiography were included in the prospec- tive study. Of them, 17 patients （sequential group） were randomly selected to use a prospectively ECG.~triggered sequential scan, while the other 15 patients （spiral group） used a retrospectively ECG-gated spiral scan. The IQ was assessed by two readers independently, using a four-point grading scale from excel- lent （grade 1） to non-assessable （grade 4）, based on the American Heart Association 15-segment model. IQ of each segment and effective dose of each natient were comDared between the two groups. Results The mean heart rate （HR） of the sequential group was 96±27 beats per minute （bpm） with a variation range of 73±25 bpm, while the mean HR of the spiral group was 86±22 bpm with a variationrange of 65±24 bpm. Both of the mean FIR （t= 1.91, P=0.243） and HR variation range （t=0.950, P=0.350） had no significant difference between the two groups. In per-segment analysis, IQ of the sequential group vs. spiral group was rated as excellent （grade 1） in 190/244 （78%） vs. 177/217 （82%） by readerl and 197/245 （80%） vs. 174/214 （81%） by reader2, as non-assessable （grade 4） in 4/244 （2%） vs. 2/217 （1%） by readerl and 6/245 （2%） vs. 4/214 （2%） by reader2. Overall averaged IQ per-patient in the sequential and spiral group showed equally good （1.27＋0.19 vs. 1.25＋0.22, Z=-0.834, P=0.404）. The effective radiation dose of the sequential group reduced significantly compared with the spiral group （4.88±1.77 mSv vs. 10.20±3.64 mSv; t=-5.372, P=0.000）. Conclusion Compared with retrospectively ECG-gated spiral scan, prospectively ECG-triggered sequential DSCT coronary angiography provides similarly diagnostically valuable images in patients with atrial fibrillation and significantly reduces radiation dose.展开更多
the close photogrammetric 3-D coordinate measurement is a newmeasuring technology in the fields of the coordinate measurementmachine (CMM) in recent years. In this method, we usually place sometargets on the measured ...the close photogrammetric 3-D coordinate measurement is a newmeasuring technology in the fields of the coordinate measurementmachine (CMM) in recent years. In this method, we usually place sometargets on the measured object and take image of targets to determinethe object coordinate. The subpixel location of target image plays animportant role in high accuracy 3-D coordinate measuring procedure.In this paper, some subpixel location methods are reviewed and somefactors which affect location precision are analyzed.展开更多
文摘Objective To evaluate the image quality （IQ） and radiation dose of 128-slice dual-source computed tomography （DSCT） coronary angiography using prospectively electrocardiogram （ECG）-triggered sequen- tial scan mode compared with ECG-gated spiral scan mode in a population with atrial fibrillation. Methods Thirty-two patients with suspected coronary artery disease and permanent atrial fibrilla- tion referred for a second-generation 128-slice DSCT coronary angiography were included in the prospec- tive study. Of them, 17 patients （sequential group） were randomly selected to use a prospectively ECG.~triggered sequential scan, while the other 15 patients （spiral group） used a retrospectively ECG-gated spiral scan. The IQ was assessed by two readers independently, using a four-point grading scale from excel- lent （grade 1） to non-assessable （grade 4）, based on the American Heart Association 15-segment model. IQ of each segment and effective dose of each natient were comDared between the two groups. Results The mean heart rate （HR） of the sequential group was 96±27 beats per minute （bpm） with a variation range of 73±25 bpm, while the mean HR of the spiral group was 86±22 bpm with a variationrange of 65±24 bpm. Both of the mean FIR （t= 1.91, P=0.243） and HR variation range （t=0.950, P=0.350） had no significant difference between the two groups. In per-segment analysis, IQ of the sequential group vs. spiral group was rated as excellent （grade 1） in 190/244 （78%） vs. 177/217 （82%） by readerl and 197/245 （80%） vs. 174/214 （81%） by reader2, as non-assessable （grade 4） in 4/244 （2%） vs. 2/217 （1%） by readerl and 6/245 （2%） vs. 4/214 （2%） by reader2. Overall averaged IQ per-patient in the sequential and spiral group showed equally good （1.27＋0.19 vs. 1.25＋0.22, Z=-0.834, P=0.404）. The effective radiation dose of the sequential group reduced significantly compared with the spiral group （4.88±1.77 mSv vs. 10.20±3.64 mSv; t=-5.372, P=0.000）. Conclusion Compared with retrospectively ECG-gated spiral scan, prospectively ECG-triggered sequential DSCT coronary angiography provides similarly diagnostically valuable images in patients with atrial fibrillation and significantly reduces radiation dose.
文摘the close photogrammetric 3-D coordinate measurement is a newmeasuring technology in the fields of the coordinate measurementmachine (CMM) in recent years. In this method, we usually place sometargets on the measured object and take image of targets to determinethe object coordinate. The subpixel location of target image plays animportant role in high accuracy 3-D coordinate measuring procedure.In this paper, some subpixel location methods are reviewed and somefactors which affect location precision are analyzed.
