自动管电流调制技术结合迭代重建算法在低剂量CT肺动脉成像中的应用

目的 探讨自动管电流调制技术结合idose4迭代重建算法在低剂量CT肺动脉成像（CTPA）中的应用价值。方法 连续收集行CTPA的受检者80例，采用随机数字表法将其分为对照组和实验组，每组40例。两组管电压均采用80 kV。对照组固定管电流为180 mAs，采用滤波反投影法重建，获得A组图像；实验组采用自动管电流调制技术，分别采用滤波反投影法和idose4迭代重建算法重建，获得B组和C组图像。统计分析A、B和C 3组的图像质量主观评分、肺动脉平均CT值、图像噪声值、肺动脉的信噪比（SNR）和对比噪声比（CNR）。比较实验组和对照组的有效剂量（E）。结果 实验组、对照组的E分别为（1.2±0.2）和（1.9±0.3）mSv，实验组的ED较对照组明显降低了36.8%（t=-3.998，P<0.05）。3组图像质量主观评分均≥3，满足临床诊断要求，且差异无统计学意义（P>0.05）。3组SNR、CNR和噪声值组间比较，差异有统计学意义（F=10.4 11、7.630、13.021，P<0.05）；而肺动脉平均CT值差异无统计学意义（P>0.05）。结论 自动管电流调制技术结合idose4迭代重建算法在低剂量CTPA检查中，在获得良好图像质量的同时，可进一步降低辐射剂量。

Application of automatic tube current modulation combined with iterative reconstruction algorithm in low-dose CT pulmonary angiography

Objective To explore the application value of automatic tube current modulation combined with iterative reconstruction algorithm (idose4) in low-dose computed tomography pulmonary angiography (CTPA). Methods A total of 80 patients with CTPA collected continuously were randomly divided into control group (n=40, 80 kV, 180 mAs) and experimental group (n=40, 80 kV, automatic tube current modulation). The data sets of control group were reconstructed with filtered-back-projection algorithm (group A), and the data sets of experimental group were reconstructed with filtered-back-projection algorithm (group B) and iterative reconstruction algorithm (group C). Subjective score, mean CT values of pulmonary artery, image noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were recorded. Effective dose (E) was compared. Results The E of experimental group was decreased by 36.8% compared to control group (t=-3.998, P<0.05). The subjective scores of 3 groups were more than 3 which could meet the requirements of clinical diagnosis, and there was no statistically significant difference (P>0.05). There was statistically significant difference for the SNR, CNR and image noise of 3 groups (F=10.411, 7.630, 13.021, P<0.05), but no statistically significant difference for the mean CT value of pulmonary artery (P>0.05). Conclusions Using automatic tube current modulation combined with iterative reconstruction algorithm in low-dose CTPA could meet the requirements of image quality, and reduce the radiation dose to a certain extent.