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目的:评估正弦图确定迭代重建(sinogram-affirmed iterative reconstruction,SAFIRE)和滤波反投影重建(filtered back projection,FBP)对于低剂量胸部CT筛查图像质量的影响。方法:收集304名行低剂量胸部CT筛查的体检者,均用双源CT以管电压120 k V、有效管电流40 m A·s进行扫描,图像使用不同技术进行重建,包括1个FBP和5个不同重建强度的SAFIRE序列(S1至S5)。由2名影像科医师分别记录噪声值和主观评价图像噪声、伪影。结果:患者的平均体重为(66.3±12.8)kg,体质量指数为23.4±3.2,平均剂量-长度乘积为(95.2±30.6)m Gy·cm,平均有效辐射剂量为(1.6±0.5)m Sv。2位医师评价的图像噪声等级、伪影等级、图像总体质量间的一致性较好(r分别为0.785、0.595和0.512)。在6个序列中,无论主观还是客观图像噪声,都是FBP最高,而图像噪声随着SAFIRE的重建强度的上升而下降,其中S3得到的图像质量最好。结论:与FBP相比,SAFIRE可显著提高低剂量胸部CT筛查的图像质量,其中S3适用于低剂量胸部CT筛查。
PURPOSE: To assess the effect of sinogram-affirmed iterative reconstruction (SAFIRE) and filtered back projection (FBP) on the image quality of low-dose chest CT scans. METHODS: Totally 304 low-dose CT chest CT scans were performed using double-source CT at a tube voltage of 120 kV and an effective tube current of 40 mA · s. Images were reconstructed using different techniques including one FBP And five SAFIRE sequences of different reconstruction intensities (S1 to S5). Two imaging physicians separately recorded the noise value and the subjective evaluation of image noise and artifact. RESULTS: The average body weight of patients was (66.3 ± 12.8) kg, body mass index was 23.4 ± 3.2, mean dose-length product was (95.2 ± 30.6) m Gy · cm and mean effective radiation dose was (1.6 ± 0.5) m Sv . The noise level, artifact level and overall quality of the images evaluated by 2 physicians were better (r = 0.785, 0.595 and 0.512, respectively). Among the six sequences, the subjective or objective image noise is the highest FBP, while the image noise decreases with the reconstruction intensity of SAFIRE, and the image quality obtained by S3 is the best. Conclusion: Compared with FBP, SAFIRE can significantly improve the image quality of low-dose chest CT screening. S3 is suitable for low-dose chest CT screening.