In three-dimensional computed tomography angiography (3D-CTA) in our facility, we usually scan the volume of the brain according to the bolus tracking method. Fluoroscopic slice is placed at the Willis’s ring and the...In three-dimensional computed tomography angiography (3D-CTA) in our facility, we usually scan the volume of the brain according to the bolus tracking method. Fluoroscopic slice is placed at the Willis’s ring and the timing of scan is determined subjectively by a radiological technologist after strong enhancement of the basal cerebral artery is confirmed. In these procedures, however, variation of scan timing is often problematic. Therefore, we design the surpassing method to place the small region-of-interest (ROI) at the basal cerebral arteries and to start CT scan automatically. In this protocol, the fluoroscopic slices of the distal internal carotid arteries are selected referring to the precontrast volume data, small ROIs are set in bilateral internal carotid arteries, and scan trigger of CT is started automatically at the threshold of 170 HU. The maximum 80 mL of iodine contrast agent 300 mgI/mL is injected intravenously at the rate of 4.0 mL/sec, and the volume of the arterial phase is scanned automatically. We measure ROIs at the internal carotid arteries based on the obtained volume data of arterial phase and estimate the optimal scan timings from the fluoroscopic CT images reformatted at the intervals of 0.1 sec. In 38 of 53 patients, placement of the small ROIs is succeeded and automatic or manual CT scan is performed. In the patients who succeed in placement of the small ROIs, optimal scan timing of the arterial phase is obtained, while in the patients who fail placement of the small ROIs, a large variation is observed in their scan timings. Their results suggest that more stable scanning of the arterial phase is available by means of small ROI placement and automatic scanning. The clinical significance is large because the stability and reproducibility of the examination provide a quantitative analysis and more accurate diagnosis.展开更多
We investigated the longitudinal positional dependence of CT number in 320-row Cone Beam Computed Tomography (CBCT) volume scan (320-row volume scan) using a simple geometric phantom (SGP) and a chest simulation phant...We investigated the longitudinal positional dependence of CT number in 320-row Cone Beam Computed Tomography (CBCT) volume scan (320-row volume scan) using a simple geometric phantom (SGP) and a chest simulation phantom (CSP) in order to evaluate its effect on proton range calculation. The SGP consisted of lung substitute material (LSM) and a cylindrical phantom (CP) made of high-density polyethylene. The CSP was an anthropomorphic phantom similar to the human chest. The two phantoms were scanned using 320-row volume scan in various longitudinal positions from the central beam axis. In experiments using the SGP, an image blur at the boundary of the two materials became gradually evident when the LSM was placed far away from the beam central axis. The image blur of the phantom was consistent with the gradation in CT number. The maximum difference in CT numbers between the 64-row helical scan and 320-row volume scan at the boundary of the two materials was consistent with approximately 50% of the relative proton stopping power. In contrast, the CT number profile in each longitudinal position was fairly consistent and longitudinal positional dependence rarely occurred in the CSP experiments. Pass lengths of CT beams through areas with widely different electron densities were shorter, and thus did not significantly impact CT numbers. Based on findings from the CSP experiments, we considered 320-row volume scan to be feasible for proton range calculation in clinical settings, although the relatively large longitudinal positional dependence of CT number should be accounted for when doing so.展开更多
目的评价全球乳腺三维超声容积成像科学研究竞争态势。方法在Web of Science数据库中检索乳腺三维超声容积成像相关的所有论文,基于此进行文献计量学分析,展示全球历年论文数量变化情况,主要国家和机构的发文数量和发文影响力,了解国际...目的评价全球乳腺三维超声容积成像科学研究竞争态势。方法在Web of Science数据库中检索乳腺三维超声容积成像相关的所有论文,基于此进行文献计量学分析,展示全球历年论文数量变化情况,主要国家和机构的发文数量和发文影响力,了解国际合作情况及高影响力论文的机构和国家分布。结果全球乳腺三维超声容积成像论文共计219篇,篇均被引频次为11.9,论文数量波动上涨,国际合作以美国最频繁。发文量排名前五位的国家依次是中国(66篇)、美国(57篇)、韩国(32篇)、荷兰(31篇)和德国(26篇),其中美国的总被引频次(942次)和篇均被引频次(16.5次/篇)均最高。发文量排名前五位的机构依次是拉德堡德大学(26篇)、台湾大学(18篇)、首尔国立大学(13篇)、密歇根大学(11篇)和复旦大学(11篇),美国通用电气公司和德国西门子公司分别以9篇和7篇跻身全球前十位,美国加州大学的总被引频次(374次)和篇均被引频次(46.8次/篇)均居全球首位。被引频次排名全球前十位的论文有5篇来自美国,2篇来自中国,2篇来自德国,1篇来自日本。结论全球乳腺三维超声容积成像相关研究数量不多,呈波动增多态势,以中国论文数量最多,美国论文影响力最大,论文产出机构虽以高校和医院为主,但通用电气和西门子两家公司也进入全球前列。我国虽研究产出相对较多,但研究成果影响力较弱。展开更多
文摘In three-dimensional computed tomography angiography (3D-CTA) in our facility, we usually scan the volume of the brain according to the bolus tracking method. Fluoroscopic slice is placed at the Willis’s ring and the timing of scan is determined subjectively by a radiological technologist after strong enhancement of the basal cerebral artery is confirmed. In these procedures, however, variation of scan timing is often problematic. Therefore, we design the surpassing method to place the small region-of-interest (ROI) at the basal cerebral arteries and to start CT scan automatically. In this protocol, the fluoroscopic slices of the distal internal carotid arteries are selected referring to the precontrast volume data, small ROIs are set in bilateral internal carotid arteries, and scan trigger of CT is started automatically at the threshold of 170 HU. The maximum 80 mL of iodine contrast agent 300 mgI/mL is injected intravenously at the rate of 4.0 mL/sec, and the volume of the arterial phase is scanned automatically. We measure ROIs at the internal carotid arteries based on the obtained volume data of arterial phase and estimate the optimal scan timings from the fluoroscopic CT images reformatted at the intervals of 0.1 sec. In 38 of 53 patients, placement of the small ROIs is succeeded and automatic or manual CT scan is performed. In the patients who succeed in placement of the small ROIs, optimal scan timing of the arterial phase is obtained, while in the patients who fail placement of the small ROIs, a large variation is observed in their scan timings. Their results suggest that more stable scanning of the arterial phase is available by means of small ROI placement and automatic scanning. The clinical significance is large because the stability and reproducibility of the examination provide a quantitative analysis and more accurate diagnosis.
文摘We investigated the longitudinal positional dependence of CT number in 320-row Cone Beam Computed Tomography (CBCT) volume scan (320-row volume scan) using a simple geometric phantom (SGP) and a chest simulation phantom (CSP) in order to evaluate its effect on proton range calculation. The SGP consisted of lung substitute material (LSM) and a cylindrical phantom (CP) made of high-density polyethylene. The CSP was an anthropomorphic phantom similar to the human chest. The two phantoms were scanned using 320-row volume scan in various longitudinal positions from the central beam axis. In experiments using the SGP, an image blur at the boundary of the two materials became gradually evident when the LSM was placed far away from the beam central axis. The image blur of the phantom was consistent with the gradation in CT number. The maximum difference in CT numbers between the 64-row helical scan and 320-row volume scan at the boundary of the two materials was consistent with approximately 50% of the relative proton stopping power. In contrast, the CT number profile in each longitudinal position was fairly consistent and longitudinal positional dependence rarely occurred in the CSP experiments. Pass lengths of CT beams through areas with widely different electron densities were shorter, and thus did not significantly impact CT numbers. Based on findings from the CSP experiments, we considered 320-row volume scan to be feasible for proton range calculation in clinical settings, although the relatively large longitudinal positional dependence of CT number should be accounted for when doing so.
文摘目的评价全球乳腺三维超声容积成像科学研究竞争态势。方法在Web of Science数据库中检索乳腺三维超声容积成像相关的所有论文,基于此进行文献计量学分析,展示全球历年论文数量变化情况,主要国家和机构的发文数量和发文影响力,了解国际合作情况及高影响力论文的机构和国家分布。结果全球乳腺三维超声容积成像论文共计219篇,篇均被引频次为11.9,论文数量波动上涨,国际合作以美国最频繁。发文量排名前五位的国家依次是中国(66篇)、美国(57篇)、韩国(32篇)、荷兰(31篇)和德国(26篇),其中美国的总被引频次(942次)和篇均被引频次(16.5次/篇)均最高。发文量排名前五位的机构依次是拉德堡德大学(26篇)、台湾大学(18篇)、首尔国立大学(13篇)、密歇根大学(11篇)和复旦大学(11篇),美国通用电气公司和德国西门子公司分别以9篇和7篇跻身全球前十位,美国加州大学的总被引频次(374次)和篇均被引频次(46.8次/篇)均居全球首位。被引频次排名全球前十位的论文有5篇来自美国,2篇来自中国,2篇来自德国,1篇来自日本。结论全球乳腺三维超声容积成像相关研究数量不多,呈波动增多态势,以中国论文数量最多,美国论文影响力最大,论文产出机构虽以高校和医院为主,但通用电气和西门子两家公司也进入全球前列。我国虽研究产出相对较多,但研究成果影响力较弱。
