儿童体模胸部双源CT扫描低剂量实验性研究
发布时间：2018-11-21 13:12
【摘要】：目的:儿童在影像学检查中单位体积所受X线剂量要远高于成年人,而且儿童对X线辐射的较成人更敏感,相同的辐射剂量下,儿童所受的损伤要远大于成年人,所以降低儿童在影像检查中所受的X线剂量是一项非常有意义的工作,我们进行这次实验的目的是在满足图像质量诊断要求的前提下,尽可能的降低患儿所受的辐射剂量,研究产生最小辐射剂量且满足诊断需要的扫描条件。方法:本次实验在双源CT下进行,设备使用西门子Definition Flash双源CT,并选择Flash Spiral模式进行胸部扫描,检查中开启CARE Dose4D技术。体模采用型号为76-414-4150,由上海滋源贸易公司经销的美国FLUKE福禄克公司生产的体模。实验按管电压的不同进行分组,60kV、80kV、100kV、120kV各一组,管电流设为自动毫安秒,设定螺距5.0,层厚为5.0 mm,重建图像采用SAFIRE3迭代技术。将体模按照胸部扫描的标准体位进行摆放,每个条件下扫描50次,每次对体模厚度进行调整以模拟不同体型的患儿。将扫描结果传输至工作站以待下一步处理。图像分析:(1)图像重建及客观评价标准:用AW4.6工作站(GE HeahhCare,USA)对图像进行重建。应用信噪比来进行图像的客观评价,具体操作方法为,体模模拟心脏中心位置设为感兴趣区,面积为3.0mm2,测量并记录这一区域的SD值和CT值。图像信噪比(SNR)的计算方法为:SNR=相应感兴趣区(ROI)的CT值/噪声SD。(2)主观评价标准:由两个副高以上职称的高年资影像医师根据临床经验对图像质量进行评价打分。将图像质量从差到优分为1~5分,具体标准为:1分,正常的组织结构显示不清楚,边缘模糊不清,完全无法区分组织结构关系;2分,组织结构比较模糊,存在一定的伪影,不能区分结构关系;3分,组织结构边缘比较模糊,有少许的伪影存在,但是正常结构的显示尚可以;4分,组织结构边缘有一些模糊不清,不过没有伪影的存在,能够清晰显示结构间的关系;5分,边缘清晰,无伪影。由SPSS22.0统计学软件进行处理,描述性数据先进行相关性分析,体表辐射剂量分别进行配对t检验。图像主观质量的评价分为一般清晰组和一般及差组,采用秩和检验进行统计学分析,检验标准设定为a=0.05。结果:统计学分析发现随着kV的降低CT有效剂量(ED)值也在降低。120 kV为3.21±0.19 msv,100 kV为1.92±0.14 msv,80 kV为0.75±0.07 msv,60 kV为0.23±0.02 msv,各组之间统计学分析均有差异性(P=0.000);主观图像质量评价60k V组与其它各组间有统计学差异(P=0.000),其余各组之间没有统计学差异。80 kV-120 kV(P=0.612),80 kV-100 kV(P=0.609),100 kV-120 kV(P=0.997)(Table 6)。客观图像质量评价,4组数据随着kV的降低,其SNR值也持续降低,统计学分析100 kV和120 kV之间没有统计学差异(P=0.344),其余各组之间均有统计学差异(P=0.000)(Table 7)。(详细数据及统计学分析见附表)。因此按照尽量使用辐射防护最优化低剂量原则(ALARA,as low as reasonably achievable),80 kV是比较理想的,既能满足诊断要求,又能尽量降低辐射剂量。结论:1图像质量随着kV值的降低而降低。2辐射剂量随着kV值得降低而减少。3 80kV以下图像质量无法满足诊断要求。4按照尽量使用辐射防护最优化低剂量原则(ALARA,as low as reasonably achievable),80 kV是比较理想的,既能满足诊断要求,又能尽量降低辐射剂量,通过将降低千伏,自动毫安秒等传统方面与最新的迭代算法相结合,达到了在降低千伏的同时,可以取得满足诊断要求的图像质量的目的。证明了80k V下通过迭代算法与自动毫安秒技术可以在极大的降低辐射剂量的同时取得满足诊断要求的图像质量。
[Abstract]:Objective: The X-ray dose of the unit volume of the child in the imaging examination is much higher than that of the adult, and the children are more sensitive to the X-ray radiation than the adult, and the damage to the children is much higher than that of the adult. Therefore, reducing the X-ray dose of the child in the image examination is a very meaningful work, and the aim of the experiment is to reduce the radiation dose of the child as much as possible on the premise of satisfying the image quality diagnosis requirement, The study produces the minimum radiation dose and meets the scan conditions required for diagnosis. Method: This experiment was performed under double-source CT. The device uses the Siemens Definition Flash dual-source CT, and selects the Flash Spiral mode for chest scanning, and the CARE Dose4D technology is opened in the examination. The model of the body model is 76-414-4150, and the body model produced by the American FLUKE Forkker Co., Ltd., which is distributed by the Shanghai AIDS Source Trading Co., Ltd. The experimental results show that the tube current is set to the automatic mA second, the pitch is 5.0, the thickness of the layer is 5.0 mm, and the reconstruction image adopts the SAFIRE3 iterative technique. The body model is placed according to the standard position of the chest scanning, and the body model is scanned for 50 times under each condition, and the thickness of the body model is adjusted at a time to simulate the children with different body shapes. the scan result is transmitted to the workstation to be processed next. Image analysis: (1) Image reconstruction and objective evaluation criteria: image reconstruction with AW4. 6 workstation (GE HehhCare, USA). The method of signal-to-noise ratio is used to evaluate the image objectively. The specific operation method is that the body model simulates the center position of the heart as the region of interest, the area is 3.0mm2, and the SD value and the CT value of the region are measured and recorded. The image-to-noise ratio (SNR) is calculated as the CT value/ noise SD of the corresponding region of interest (ROI). (2) Subjective evaluation standard: The image quality is evaluated and scored according to the clinical experience by a high-year-time image doctor with two sub-high professional titles. the quality of the image is divided into 1-5 points from the difference to the excellent, the specific standard is: 1 point, the normal tissue structure is not clear, the edge is blurred, the structure relationship of the tissue can not be distinguished completely, The edge of the tissue structure is relatively vague, with a few false shadows, but the display of the normal structure can still be; 4 points, the edge of the tissue structure has some ambiguity, but there is no pseudo-shadow, and the relationship between the structures can be clearly displayed; 5 points, sharp edges and no artifacts. The statistical software of SPSS22. 0 is used for processing, and the descriptive data is analyzed first, and the body surface radiation dose is respectively matched with t-test. The evaluation of the subjective quality of the image is divided into the general and the general and the difference group, and the statistical analysis is carried out by the rank sum test, and the test standard is set to a = 0.05. Results: The statistical analysis found that the effective dose (ED) of CT was also reduced with the decrease of the effective dose (ED). 120 kV was 3.21-0.19mv, 100 kV was 1.92-0.14msv, 80 kV was 0.75kV, 07msv, 60kV was 0.23-0.02msv, and there was a difference between the groups (P = 0.000). There was no statistical difference between the 60k V group and the other groups (P = 0.000), and there was no statistical difference between the other groups. 80 kV-120 kV (P = 0. 612), 80 kV-100 kV (P = 0. 609), 100 kV-120 kV (P = 0. 997) (Table 6). There was no statistical difference between 100 kV and 120 kV (P = 0.344), and there was no statistical difference between the other groups (P = 0.000) (Table 7). (See attached table for detailed data and statistical analysis). Therefore, as far as possible, the low-dose principle of radiation protection (ALARA, as low as possible) and 80 kV is ideal, which can not only meet the diagnostic requirements, but also reduce the radiation dose as much as possible. Conclusion: 1 The image quality is reduced with the decrease of the kV value. The radiation dose is reduced with the decrease of the kV. The quality of the image below 3 80kV can not meet the diagnostic requirements. The method not only can meet the diagnosis requirement, but also can reduce the radiation dose as much as possible, and can achieve the aim of meeting the image quality required by the diagnosis at the same time of reducing the kilovoltage by combining the traditional aspects such as the reduction of the kilovoltage, the automatic milliampere second and the like with the latest iteration algorithm. It is proved that the image quality that can meet the diagnosis requirement can be obtained at the same time when the radiation dose is greatly reduced by the iterative algorithm and the automatic milliamp second technology under the 80k V.
【学位授予单位】：河北医科大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R816.92
本文编号：2347053
[Abstract]:Objective: The X-ray dose of the unit volume of the child in the imaging examination is much higher than that of the adult, and the children are more sensitive to the X-ray radiation than the adult, and the damage to the children is much higher than that of the adult. Therefore, reducing the X-ray dose of the child in the image examination is a very meaningful work, and the aim of the experiment is to reduce the radiation dose of the child as much as possible on the premise of satisfying the image quality diagnosis requirement, The study produces the minimum radiation dose and meets the scan conditions required for diagnosis. Method: This experiment was performed under double-source CT. The device uses the Siemens Definition Flash dual-source CT, and selects the Flash Spiral mode for chest scanning, and the CARE Dose4D technology is opened in the examination. The model of the body model is 76-414-4150, and the body model produced by the American FLUKE Forkker Co., Ltd., which is distributed by the Shanghai AIDS Source Trading Co., Ltd. The experimental results show that the tube current is set to the automatic mA second, the pitch is 5.0, the thickness of the layer is 5.0 mm, and the reconstruction image adopts the SAFIRE3 iterative technique. The body model is placed according to the standard position of the chest scanning, and the body model is scanned for 50 times under each condition, and the thickness of the body model is adjusted at a time to simulate the children with different body shapes. the scan result is transmitted to the workstation to be processed next. Image analysis: (1) Image reconstruction and objective evaluation criteria: image reconstruction with AW4. 6 workstation (GE HehhCare, USA). The method of signal-to-noise ratio is used to evaluate the image objectively. The specific operation method is that the body model simulates the center position of the heart as the region of interest, the area is 3.0mm2, and the SD value and the CT value of the region are measured and recorded. The image-to-noise ratio (SNR) is calculated as the CT value/ noise SD of the corresponding region of interest (ROI). (2) Subjective evaluation standard: The image quality is evaluated and scored according to the clinical experience by a high-year-time image doctor with two sub-high professional titles. the quality of the image is divided into 1-5 points from the difference to the excellent, the specific standard is: 1 point, the normal tissue structure is not clear, the edge is blurred, the structure relationship of the tissue can not be distinguished completely, The edge of the tissue structure is relatively vague, with a few false shadows, but the display of the normal structure can still be; 4 points, the edge of the tissue structure has some ambiguity, but there is no pseudo-shadow, and the relationship between the structures can be clearly displayed; 5 points, sharp edges and no artifacts. The statistical software of SPSS22. 0 is used for processing, and the descriptive data is analyzed first, and the body surface radiation dose is respectively matched with t-test. The evaluation of the subjective quality of the image is divided into the general and the general and the difference group, and the statistical analysis is carried out by the rank sum test, and the test standard is set to a = 0.05. Results: The statistical analysis found that the effective dose (ED) of CT was also reduced with the decrease of the effective dose (ED). 120 kV was 3.21-0.19mv, 100 kV was 1.92-0.14msv, 80 kV was 0.75kV, 07msv, 60kV was 0.23-0.02msv, and there was a difference between the groups (P = 0.000). There was no statistical difference between the 60k V group and the other groups (P = 0.000), and there was no statistical difference between the other groups. 80 kV-120 kV (P = 0. 612), 80 kV-100 kV (P = 0. 609), 100 kV-120 kV (P = 0. 997) (Table 6). There was no statistical difference between 100 kV and 120 kV (P = 0.344), and there was no statistical difference between the other groups (P = 0.000) (Table 7). (See attached table for detailed data and statistical analysis). Therefore, as far as possible, the low-dose principle of radiation protection (ALARA, as low as possible) and 80 kV is ideal, which can not only meet the diagnostic requirements, but also reduce the radiation dose as much as possible. Conclusion: 1 The image quality is reduced with the decrease of the kV value. The radiation dose is reduced with the decrease of the kV. The quality of the image below 3 80kV can not meet the diagnostic requirements. The method not only can meet the diagnosis requirement, but also can reduce the radiation dose as much as possible, and can achieve the aim of meeting the image quality required by the diagnosis at the same time of reducing the kilovoltage by combining the traditional aspects such as the reduction of the kilovoltage, the automatic milliampere second and the like with the latest iteration algorithm. It is proved that the image quality that can meet the diagnosis requirement can be obtained at the same time when the radiation dose is greatly reduced by the iterative algorithm and the automatic milliamp second technology under the 80k V.
【学位授予单位】：河北医科大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R816.92
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