【作者】 彭刚；

【导师】 曾勇明；

【作者基本信息】 重庆医科大学 ， 影像医学与核医学， 2011， 硕士

【摘要】 目的:通过实验对中国人仿真胸部体模从CT断层解剖和组织X线衰减等效性两方面与正常成人作对比研究,评价其临床和科研价值。方法:选取正常成年男性自愿者(门诊健康体检人员,年龄20～50岁,身高165～170 cm,体重60 kg左右)10人作为对照。使用GE公司Brightspeed Elite 16排螺旋CT以相同的技术参数分别对CDP-1C型中国人仿真胸部体模和正常成人行常规胸部CT扫描,根据CT横断面图像所反映的解剖结构判断两者的相似程度;根据对各组织器官CT值测量后分析体模组织的X线衰减等效程度。结果:在CT断层解剖方面,中国人仿真胸部体模与正常成人基本相似;在组织X线衰减等效性方面,体模与人体肺、心脏、脊柱CT值比较,差异无统计学意义(P >0.05),体模肝脏与人体肝脏偏差程度最大,为4.49%。体模的组织器官CT值与人体组织器官偏差程度均小于5%,符合实验型体模标准。结论:中国人仿真胸部体模作为客观的评价工具,可以应用于CT低剂量技术的实验研究。第二部分多层螺旋CT扫描患者器官剂量的实验研究目的:利用中国人仿真胸部模型来测量不同噪声指数下胸部各组织器官的吸收剂量,计算有效剂量(ED)并对MSCT胸部扫描进行剂量评估。方法:通过在体模内布放热释光剂量计(TLD)来测量不同噪声水平下各组织器官的吸收剂量,并记录相应的平均剂量长度乘积(DLP);将两者分别换算为ED后进行对比研究,分析自动管电流调制(ATCM)技术时不同噪声指数胸部CT扫描的剂量水平。统计学方法选择单因素t检验,采用SPSS 12.0统计软件进行分析。结果:当噪声指数从8.5逐渐增至22.5时,DLP均值从393.57mGy/cm递减至78.75mGy/cm,各器官吸收剂量呈下降趋势(以肺为例,平均吸收剂量从22.38 mGy递减至3.66mGy)。应用DLP均值所计算的ED较器官吸收剂量计算的ED偏低(以噪声指数为8.5为例,两种方法的ED分别为6.69和8.77 mSv)。结论:应用中国人仿真体模来进行CT剂量评估更为准确;基于ATCM技术的胸部CT扫描噪声指数设定至少应大于8.5。更多还原

【Abstract】 Objective: To evaluate the clinical and research value of anthropomorphic chest phantom from CT sectional anatomy and tissue equivalence of X-ray attenuation by comparing with normal adults.Methods: Ten clinically healthy male volunteers, aged 20 to 50 years old, with an average height of 165 ~ 170 cm, and weight of 60 kg served as a control group. The GE Bright speed Elite 16-slice spiral CT scanner served as the choice for the study. The Chinese anthropomorphic chest phantom(CDP-1C) and the normal adults were scanned with the same scanning parameters, according to the Sectional image and the CT value of the various tissues and organs to evaluate the Similarity of Anatomy and the tissue equivalence of X-ray attenuation respectively.Results: On anatomic morphology, the Chinese anthropomorphic chest phantom was basically similar to the normal adult; on tissue equivalence of X-ray attenuation , no significant difference of CT value were shown between the lung,heart and spine of phantom and human(P >0.05). The maximum deviation on the liver was 4.49%. The CT value error of each tissue and organ was less than 5% between phantom and human, which is reaching the standard of experiment.Conclusion: The Chinese anthropomorphic chest phantom can be used to study of low-dose CT based on objective evaluation criteria.PART2 THE MEASUREMENT OF ORGANIC RADIATION DOSE WITH MULTI-SLICE CT BY USING THE CHINESE ANTHROPOMORPHIC CHEST PHANTOMObjective: Using the Chinese anthropomorphic chest phantom to measure absorbed dose of various tissues and organs under different noise index, calculation of the effective dose(ED) was used to evaluate the chest scanning with MSCT.Methods: To measure absorbed dose of various tissues and organs under different noise index by laying thermoluminescent dosimeters(TLD) inside the phantom, and the corresponding dose-length product(DLP) was recorded. Both of them were later converted into ED and comparative studies to analyze dose levels of chest CT scanning with automatic tube current modulation(ATCM) under different noise index.Statistical analysis is slected t test of single factor, using SPSS12.0 statistical software to analyze.Results: As the noise index increase from 8.5 to 22.5,The DLP decrease from 393.57mGy/cm to 78.75mGy/cm and the organs dose decline,for example,the average absorbed dose decrease from 22.38 mGy to 3.66mGy in lung. Compared with ED calculating by absorbed dose, The ED calculating by DLP was lower,and the ED are 6.69 mSv and 8.77 mSv respectly when the noise index is set 8.5.Conclusion: Application of the Chinese anthropomorphic chest phantom to carry out CT dose assessment is more accurate. The noise index should be set larger than 8.5 during the chest CT screening based on ATCM technique.更多还原