迭代重建技术（ASIR-V）在胸部CT检查中降低辐射剂量的初步研究

发布时间：2019-03-07 16:01

【摘要】：目的:探讨迭代重建技术(ASIR-V)在胸部Revolution CT检查中降低辐射剂量的应用价值。方法:随机收集120例拟行胸部RevolutionCT平扫的患者,将其随机分成4组,每组30例,分别在ASIR-V权重为0%(A组)、20%(B组)、40%(C组)、60%(D组)时扫描。扫描条件:噪声指数均设定为9,管电压为120KV,管电流为自动毫安(Smart mA 80-350),X线球管旋转速度0.5s,螺距0.992:1。患者检查前均测量身高及体重,并计算身高体重指数(body mass index,BMI)。记录每例患者扫描时的容积CT剂量指数(volume computed tomography dose index,CTDIvol)、剂量长度乘积(dose length product,DLP),并根据公式有效剂量(effective dose,ED)(mSv)=k(mSv·mGy-1·cm-1)×DLP(mGy·cm),计算ED值(k=0.019),对四组CT图像进行客观评价,测量其噪声(SDa)、肺动脉与竖脊肌的对比噪声比(CNRp)、肺动脉信噪比(SNRp)。并对四组图像肺窗及纵隔窗图像进行主观质量评分。然后采用单因素方差分析处理各组间的差异。结果:(1)随着ASIR-V权重增加,患者的有效剂量逐渐降低,两者呈负相关,四组数据间存在统计学差异(P0.05),A组有效剂量最大(5.13±0.48 mSv),D组有效剂量最小(1.97±0.50 mSv),剂量仅为A组的38.4%;(2)四组噪声之间存在统计学差异(P0.05),前三组噪声(SDa)随着ASIR-V权重的增加,数值逐渐减小,而D组噪声为四组中最大(8.81±1.91);(3)四组肺动脉与竖脊肌的对比噪声比(CNRp)存在统计学差异(P0.05),CNRp在C组(40%ASIR-V)最大(1.54±1.01),而在B组最小(0.998±1.07);(4)四组肺动脉信噪比(SNRp)在不同ASIR-V权重时也存在统计学差异(P0.05),SNRp在前三组呈递增趋势,C组最大(6.10±1.90),D组降为最低(4.84±1.60);(5)图像质量主观评价方面,四组主观评价分值之间存在统计学差异(P0.05),四组评分呈递减趋势,且前三组递减趋势比较微弱,D组评分明显降低,A组评分最高,值为14.2±1.03,D组评分最低,为8.7±1.12。结论:综合有效辐射剂量、图像质量的主客观指标,Revolution CT行胸部平扫时采用40%权重ASIR-V能有效降低辐射剂量,同时又能保证图像的质量。
[Abstract]:Objective: to evaluate the value of iterative reconstruction technique (ASIR-V) in reducing radiation dose in thoracic Revolution CT. Methods: one hundred and twenty patients were randomly divided into 4 groups (30 patients in each group) with ASIR-V of 0% (group A), 20% (group B), 40% (group C) and 60% (group D) when the ASIR-V weight was 0% (group A), 20% (group B), 40% (group C) and 60% (group D), respectively. Scanning conditions: noise figure is set to 9, tube voltage is 120kV, tube current is automatic milliampere (Smart mA 80kv 350), rotating speed of X-ray tube is 0.5s, pitch of screw is 0.992ml. Height and weight were measured before examination, and body height and body mass index (body mass index,BMI) were calculated. The volume CT dose index (volume computed tomography dose index,CTDIvol) and the dose length product (dose length product,DLP) of each patient were recorded at the time of scanning, and the effective dose of (effective dose, was calculated according to the formula. ED) (mSv) = k (mSv 路mGy-1 cm-1) 脳 DLP (mGy cm), calculated Ed value (k = 0.019). Four groups of CT images were evaluated objectively, and the noise ratio of (SDa), pulmonary artery to vertical spinal muscle was measured by comparing the noise to noise ratio of (SDa), pulmonary artery to vertical spinal muscle. Pulmonary artery signal-to-noise ratio (SNRp). The subjective quality of lung window and mediastinal window were evaluated. Then one-way ANOVA was used to deal with the differences among groups. Results: (1) with the increase of the weight of ASIR-V, the effective dose of the patients decreased gradually, and there was a negative correlation between the two groups. There was statistical difference among the four groups (P 0.05). The effective dose of), A group was the highest (5.13 卤0.48 mSv),). The effective dose in group D was only 38.4% of that in group A (1.97 卤0.50 mSv),). (2) there was statistical difference among the four groups of noise (P0.05). The noise (SDa) of the first three groups decreased gradually with the increase of ASIR-V weight, while the noise of group D was the highest among the four groups (8.81 卤1.91). (3) there was a significant difference in the noise ratio between the pulmonary artery and the vertical spine muscle in the four groups (P0.05), CNRp was the largest (1.54 卤1.01) in group C (40%ASIR-V), and the smallest (0.998 卤1.07) in group B; the noise ratio of (CNRp) was significantly higher in group C (40%ASIR-V) than in group B; (4) there was significant difference in the signal-to-noise ratio (SNR) (SNRp) of pulmonary artery between the four groups when the weight of ASIR-V was different (P0.05), SNRp increased in the first three groups, and the highest in group C (6.10 卤1.90), D) was the lowest (4.84 卤1.60); (5) in the subjective evaluation of image quality, there was a statistical difference among the four groups (P0.05), the scores of the four groups showed a decreasing trend, and the first three groups showed a weak decreasing trend, the score of Group D was significantly lower, and the score of Group A was the highest. The score of group D was the lowest (8.7 卤1.12). Conclusion: combining the effective radiation dose and the subjective and objective index of image quality, Revolution CT, 40% weighted ASIR-V can effectively reduce the radiation dose and guarantee the quality of the image during chest plain scan.
【学位授予单位】：苏州大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：R816.4

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