目的:探讨CT血管造影(CTangiography,CTA)后处理技术容积重建(volumerendering,VR)中阈值、最大密度投影(maximum intensity projection,MIP)中窗宽及窗位、视野(Field of view,FOV)对血管管径测量的影响及相关关系。方法:建立9个不同...目的:探讨CT血管造影(CTangiography,CTA)后处理技术容积重建(volumerendering,VR)中阈值、最大密度投影(maximum intensity projection,MIP)中窗宽及窗位、视野(Field of view,FOV)对血管管径测量的影响及相关关系。方法:建立9个不同密度的血管模型,使用不同的FOV、阈值(VR)、窗宽(MIP)测量不同密度血管模型管径,分析标准阈值、窗宽与血管模型管径的关系,并与CT值进行相关性分析。统计临床脑血管CTA MIP重建病例30例的窗宽及窗位,与实验结果进行比较。结果:VR重建,阈值和血管模型管径呈明显负相关(r=-0.847,P=0.000);MIP重建,窗宽和血管模型管径呈明显正相关(r=0.983,P=0.000);FOV和血管模型管径无相关性(r=-0.042,P=0.381)。临床脑血管CTAMIP重建窗宽明显增宽,夸大了血管真实管径。结论:CTA血管管径测量的准确性受VR重建阈值、MIP重建窗宽窗位的影响,根据血管内对比剂密度对这些参数进行调整,保证测量血管管径的可靠性和准确性。展开更多
SiOx （x = 0-2） films were deposited on BK-7 substrates by a low frequency reactive magnetron sputtering system with the oxygen flow rate （OFR） changing from 0 to 30 sccm. The samples were characterized by atomic f...SiOx （x = 0-2） films were deposited on BK-7 substrates by a low frequency reactive magnetron sputtering system with the oxygen flow rate （OFR） changing from 0 to 30 sccm. The samples were characterized by atomic force microscopy, spectrophotometer, and X-ray photoelectron spectroscopy. The extinction coefficient and refractive index decrease, while the optical transmittance increases with the increase of OFR from 0 to 17 sccm. The root mean square surface roughness has a maximum at 10 sccm OFR. The highest deposition rate is at 15 sccm OFR. Our results show that the films deposited at 20 sccm OFR are stoichiometric silica with relatively high deposition rate, low extinction coefficient, and low surface roughness. Therefore, a precise control of OFR is very important to obtain high quality films for optical applications.展开更多
基金This work was supported by the National Natural Sci-ence Foundation of China under Grant No. 50121202and 10174073
文摘SiOx （x = 0-2） films were deposited on BK-7 substrates by a low frequency reactive magnetron sputtering system with the oxygen flow rate （OFR） changing from 0 to 30 sccm. The samples were characterized by atomic force microscopy, spectrophotometer, and X-ray photoelectron spectroscopy. The extinction coefficient and refractive index decrease, while the optical transmittance increases with the increase of OFR from 0 to 17 sccm. The root mean square surface roughness has a maximum at 10 sccm OFR. The highest deposition rate is at 15 sccm OFR. Our results show that the films deposited at 20 sccm OFR are stoichiometric silica with relatively high deposition rate, low extinction coefficient, and low surface roughness. Therefore, a precise control of OFR is very important to obtain high quality films for optical applications.
