CT图像噪声与辐射剂量及对比剂浓度的相关性研究

Correlation between CT Image Noise,Radiation Dose and Contrast Agent Concentration

目的探讨CT图像噪声与辐射剂量及对比剂浓度的相关性。方法配制浓度为0.5~50.0 mg/ml,间隔0.5 mg/ml的100份对比剂样本,在15种不同扫描条件下扫描,测量并记录CT图像噪声、辐射剂量,分析其是否与扫描条件有关,以及CT图像噪声与辐射剂量及对比剂浓度的关系。不同扫描条件下CT图像噪声是否有差异采用方差分析,辐射剂量与扫描条件的关系采用Pearson相关分析,CT图像噪声与辐射剂量及对比剂浓度的关系采用Pearson相关分析并计算其回归方程,根据方程建模计算CT图像噪声及辐射剂量同时为最低的节点。结果不同扫描条件下,CT图像噪声差异均具有统计学意义(P<0.05)。辐射剂量与管电压及管电流均有相关性(r=0.996~1.000,P<0.05)。CT图像噪声与辐射剂量的相关方程分别为100 m A:N100mA=-37.565Ln(D100mA)+164.893,R2=0.905,P=0.013;200 m A:N200mA=-32.711Ln(D200mA)+167.456,R2=0.935,P=0.007;280 m A:N280mA=-29.549Ln(D280mA)+158.628,R2=0.925,P=0.009。其两者同时最小的节点分别为100 m A:N100mA=31.81,D100mA=34.56 m Gy·cm;200 m A:N200mA=47.33,D200mA=39.34 m Gy·cm;280 m A:N280mA=50.62,D280mA=38.68 m Gy·cm(D为辐射剂量,N为图像噪声,R2为决定系数)。CT图像噪声与对比剂浓度有一定的相关性(r=0.512~0.777)。结论 CT图像噪声与辐射剂量和对比剂浓度有一定相关性,实际工作中要意识到这一点,并利用其达到保证图像质量的前提下,减少辐射剂量的目的。

Objective To investigate the correlation between CT image noise,radiation dose and contrast agent concentration.Methods A sum total of 100 contrast medium samples with concentrations ranging from 0.5 mg/ml to 50.0 mg/ml and an interval of 0.5 mg/ml were administered under 15 different scanning conditions.All of the CT image noise and radiation doses were measured and recorded.To find out the relationship between CT image noise and radiation dose,CT image noise and contrast agent concentration were analyzed for whether the scanning conditions have a relationship with image noise and the radiation dose.The difference in image noises under different scanning conditions was analyzed by one-way ANOVA test,while the relationship of radiation dose and scanning conditions was tested by correlation analysis.The relationship between CT image noise and radiation dose,CT image noise and contrast agent concentration was analyzed by correlation and their regression equation was calculated.According to the equation,the node with the least image noise and the lowest radiation dose was marked.Results The image noises had statistical difference under different scanning conditions(P<0.05).Radiation dose was correlated with tube voltage and tube current(r=0.996-1.000,P<0.05).The correlation equations of image noise and radiation dose were 100 m A:N100mA=-37.565 Ln(D100mA)+164.893,R2=0.905,P=0.013;200 m A:N200mA=-32.711 Ln(D200mA)+167.456,R2=0.935,P=0.007;280 m A:N280 mA=-29.549 Ln(D280 mA)+158.628,R2=0.925,P=0.009.The nodes with the least image noise and the lowest radiation dose were 100 m A:N100mA=31.81,D100mA=34.56 m Gy/cm;200 m A:N200mA=47.33,D200mA=39.34 m Gy/cm;280 m A:N280 mA=50.62,D280 mA=38.68 m Gy/cm(D for radiation dose,N for image noise).Image noise and contrast agent concentration had a certain correlation(r=0.512-0.777).Conclusion There was a certain correlation between image noise and radiation dose,as well as image noise and contrast agent concentration.On the premise of better image quality,the radiation dose could be reduced according to such correlations.