排序方式: 共有35条查询结果,搜索用时 15 毫秒
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目的:探讨多排螺旋CT对肺组织灌注成像合适的注射速率.方法:研究采用配对设计,处理因素为对比剂的注射速率,分别为3、4、5、6 ml/s,每组15例志愿者随机入组,分成4组共60例进行灌注扫描,所得图像经后处理测量肺门层面的两肺组织对比剂至峰值时间及峰值.结果:注射速率对两肺组织至峰值时间有显著性影响.其中注射速率为5 ml/s、6 ml/s组肺组织至峰值时间及峰值无统计学显著性差异(P>0.05),3 ml/s、4 ml/s两组与5 ml/s、6 ml/s两组依次相比较肺组织至峰值时间延长,峰值降低.结论:注射速率≥5 mL/s时肺组织灌注成像可获得满意效果. 相似文献
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目的 探讨自然心率下舣源CT Flash螺旋心脏模式和前瞻性心电触发序列模式的冠状动脉成像质量及辐射剂量,以实现个性化低剂量冠状动脉扫描模式的选择.方法 将60例行CT冠状动脉血管成像(CTCA)检查的患者分为2组,A组27例行Flash螺旋心脏模式扫描,入组标准:心率65次/min(bpm)以下,窦性心律且律齐,心率波动范围在±5 bpm以内.采集期相为60%R-R间期.B组33例行前瞻性心电触发序列(SAS)扫描,入组标准:(1)心率≥65 bpm,(2)心律不齐、早搏、心房颤动.排除标准:屏气不佳者.采集期相:(1)心率≤75 bpm为60%-80%R-R间期,(2)心率>75 bpm为30%-50%R-R间期,(3)心律不齐、早搏、心房颤动为20%~90%R-R间期.2组的管电压均随体质量指数(BMI)调整,BMI≥25.0 kg/m2管电乐采用120 kV,BMI<25.0 kg/m2管电压采用100 kV,A组的BMI为(24.6±1.0)ks/m2,B组的BMI为(24.6±0.9)kg/m2.对2组扫描的冠状动脉分别做图像后处理,应用两独立样本t检验对2组患者冠状动脉段图像质量评分及辐射剂量进行统计分析.结果 可评价的冠状动脉节段748段,其中A组336段、B组412段;A组冠状动脉段图像质量评价为优良者达98.2%(330/336),B组的达98.1%(404/412),2组图像质量评分差异无统计学意义(t=0.513,P=0.608).A组平均有效剂量为(0.74 4-0.29)mSv,B组为(3.67±1.37)mSv,2组之间差异有统计学意义(t=-10.858,P=0.000).结论 2组个性化低剂量冠状动脉扫描模式可在保证图像质量的同时显著降低辐射剂量.Abstract: Objective To compare the quality and radiation doses of coronary artery angiography under the natural heart rate condition between Flash spiral heart mode and prospective electrocardiogramtriggering sequence mode using dual-source,in order to choose personalized low doses of coronary artery scanning mode.Methods Sixty patients who underwent coronary angiography(CTA)on a 128-slice,dualsource CT scanner were divided into 2 group i.e,group A(27cases)and group B(33 cases).Flash spiral heart scan mode was employed for group A.Inclusion criteria included:heart rate<65 bpm.regular sinus rhythm,heart rate fluctuation less than ±5 bpm.Date acquisition was set at 60% of the R-R interval.Prospective electrocardiogram-triggering sequence scan mode(SAS)was performod for group B.Inclusion criteria included:(1)heart rate≥65 bpm,(2)arrhythmias,premature beat,fibrillation atrial.Exclusion criteria included:bad holding breath.Date acquisition(1)At low heart rate(≤75 bpm),date acquisition was set at 60%-80%of the R-R interval.(2)At high heart rate(>75 bpm),date acquisition was set at 30%-50%of the R-R interval. (3)At the arrhythmias,premature beat,fibrillation atrial,date acquisition was set at 20%-90%of the R-R interval.In both gronps,patients with a BMI≥25.0kg/m2 were examined with a tube voltage of 120 kV.while the other patients with a BMI<25.0 kg/m2 were examined with a tube voltage of 100 kV.The BMl was(24.6±1.0)kg/m2 in group A,while that was (24.6±0.9)kg/m2 in group B.In both groups,all images were transferred to the workstation for further processing and analysis.The imaging quality of coronary artery segments and the radiation dose were compared with t test.Results A total of 336 coronary artery segments were evaluated in group A and 412 segments were evaluated in group B.The imaging quality of coronary artery segments were scored.Excellent or good was achieved in 98.2%(330 of 336)artery segments in group A,and that was 98.1%(404 of 412)in group B.There was no statistical difference in imaging quality between the two groups(t=0.513,P=0.608).The average effective dose was(0.74±0.29)mSv in group A,whereas that was(3.67±1.37)mSv in group B.There was a significant difference between the two groups(t=-10.858,P=0.000).Conclusions The personalized low doses coronary artery scanning mode can substantially reduce radiation damage while preserving good imaging quality. 相似文献
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骨折金属固定术后双能量CT图像质量的初步研究 总被引:1,自引:0,他引:1
目的探讨骨折金属固定术后双能量CT单能谱成像技术的图像质量。方法对36例骨折金属固定术后复查的患者使用双源CT双能量扫描,采用双能量扫描程序,一次性扫描采集2个不同能量的数据。所得原始数据的后处理采用100 kV及140 kV 2个不同能量的数据用单能谱成像技术利用不同的能谱直接进行不同密度的金属减影。所得数据进行单能谱成像法重建,包括多平面重建技术(MPR)、容积显示(VR)和最大密度投影(MIP),对图像质量进行评价。结果 MPR、VR、MIP 3种重建技术所得图像质量均可满足影像学评价,细节显示清楚,固定物位置及骨折对位或对线情况显示清晰;对于金属固定物的准确位置显示、骨折处小骨片或椎管内、椎皮质细节情况显示欠佳。图像质量为优者平均达90.7%。无图像伪影占87.0%。结论双能量单能谱CT扫描技术能够有效去除金属伪影,清晰显示骨折金属固定术后的细微结构,图像质量较高。 相似文献
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【摘要】目的:比较容积CT剂量指数(CTDIvol)与体型特异性剂量估算(SSDE)两种测量方法测得的辐射剂量在儿童胸部CT检查中的差异。方法:回顾性分析2020年1月至2021年8月行胸部CT检查的131例儿童的病例资料,所有患儿图像均能满足诊断要求。根据患儿图像中心层面的左右径(LAT)进行分组:A组LAT<20cm,22例;B组20≤LAT<23cm,20例;C组23≤LAT<26cm,21例;D组26≤LAT<29cm,25例;E组29≤LAT<32cm,23例;F组LAT≥32cm,20例。测量患儿胸部中心层CT图像的最大左右径,手动勾画体表最小的范围,不包括检查床床板,测量平均CT值、面积,记录患儿的CTDIvol,并计算转换因子fWED和SSDE,比较 CTDIvol与SSDE的差异。结果:各组的左右径(LAT)、转换因子(fWED)、水当量直径(WED)差异均有统计学意义(P值均<0.05)。6组CTDIvol与SSDE差异度依次为223.06%、213.01%、203.44%、181.58%、173.58%、157.87%。各组CTDIvol与SSDE均呈正相关。结论:儿童胸部CT检查中,CTDIvol较SSDE低估了患儿的辐射剂量,且患儿中心层面左右径越小,被低估的辐射剂量越大。 相似文献