【作者】 张伟；

【导师】 龚建平；

【作者基本信息】 苏州大学 ， 影像医学与核医学， 2006， 硕士

【摘要】 本研究采用低Kv-CT扫描,以水模和非胰腺患者为研究对象,分为两部分。第一部分:低Kv-CT扫描参数的优化设计目的:筛选低Kv-CT扫描的优化参数。材料和方法:应用GE Hispeed/I型CT机、标准水模及Catphan? 500测量水模,扫描参数如下:电压分别为80Kv、100Kv和120Kv,mAs值分别为200mAs、300mAs、400mAs、500mAs和600mAs,层厚分别为1、3、5、7和10毫米,层间距0毫米,SFOV:48厘米,DFOV:35厘米,对Catphan? 500水模进行轴扫。扫描完毕后立即行soft、standard、lung、detail、bone和edge参数重建。将常规120Kv-200mAs组、100Kv-300mAs组和80Kv-400mAs组对标准水模进行螺旋扫描,螺距分别为1.0、1.5和2.0。测量CTDIW、噪声、对比噪声比和低密度分辨率并分析。结果:80Kv-200～600mAs及100Kv-200～300mAs的CTDIW值低于常规120Kv-200mAs,噪声相应增高。120Kv200mAs组、100Kv-300mAs组和80Kv-400mAs组的CNR值及低密度分辨率没有统计学差异,p>0.05。结论:80Kv-400mAs是胸部低Kv-CT扫描的优化参数;100Kv-300mAs是腹部低Kv-CT扫描的优化参数。第二部分:低Kv-CT扫描在胰腺增强中的应用价值目的:探讨低Kv-CT扫描在胰腺增强中的应用价值。材料和方法:将120例非胰腺疾病患者按不同扫描参数和注射扫描随机分为4组,Ⅰ组(120Kv,200mAs,注射速率3.5ml/s),Ⅱ组(100Kv,300mAs,注射速率3.5ml/s),Ⅲ组(120Kv,200mAs,注射时间30秒),Ⅳ组(100Kv,300mAs,注射时间30秒),每组30例,分别行动脉期增强扫描,计算各组的胰腺绝对强化值及有效剂量,并比较图像质量。结果:Ⅰ组、Ⅱ组、Ⅲ组、Ⅳ组患者的胰腺绝对强化值分别为78.88±12.71 Hu、101.99±18.82 Hu、83.15±17.47 Hu、105.47±27.66 Hu。Ⅰ、Ⅱ组之间和Ⅲ、Ⅳ组之间有明显统计学差异,p<0.01。Ⅱ组比Ⅰ组的有效剂量降低了15.9%,Ⅳ组比Ⅲ组降低了16.8%,而四组之间图像质量没有差异。结论:在降低X线照射剂量的情况下,腹部低Kv-CT扫描(100Kv、300mAs)提高了胰腺的强化程度,而图像质量没有降低。更多还原

【Abstract】 This study adopted low-kilovoltage CT scanning and took phantoms and patients without pancreatic disease as research materials, which was divided into two parts.Part One: Optimization of low-kilovoltage CT scanning parameters:phantom studyObjective: Sieving optimal scanning parameters of low-kilovoltage CT scanning. Materials and methods: The phantom (Catphan500) and a standard phantom were scanned with GE Hispeed/I helical CT scanner. The scanning parameters were as follows: The tube voltage: 80kv, 100kv and 120kv respectively; the tube current-time product settings: 200-600mAs; section thickness: 1-10mm; section interval: 0mm; scan field of view: 48cm; display field of view: 35cm. After scanning, the images were reconstructed by soft, standard, lung, detail, bone, edge, reconstruction algorithm. The standard phantom was scanned at 120kV and 200mAs, 100kV and 300mAs, 80kV and 400mAs, pitch: 1.0, 1.5 and 2.0. Weighted CT dose index, image noise, contrast-to-noise ratio and low-contrast detectability were measured. Results: The CTDIW at 80Kv and 200-600mAs and 100kV and 200-300mAs were lower than 120kV and 200mAs, the image noise were higher accordingly. The differences of contrast-to-noise ratio and low-contrast detectability were not significant among 80Kv and 400mAs, 100kV and 300mAs, 120kV and 200mAs, p<0.05. Conclusion: The 80Kv and 400mAs was the optimal parameters of chest low-kilovoltage CT scanning, 100kV and 300mAs of abdomen.Part Two: Application of low-kilovoltage CT scanning to pancreatic enhancementObjective: To assess the value of low-kilovoltage CT scanning enhanced scanning of pancreas. Materials and methods: A total of 120 patients were divided at random into four groups with different scanning parameters and injection techniques. GroupⅠ更多还原