自动管电流调制技术结合迭代重建算法在成人盆腔低剂量CT中的初步应用

目的 探讨成人盆腔低剂量CT成像中应用自动管电流调制技术（ATCM）结合适应性统计迭代重建（ASIR）算法降低辐射剂量的可行性。方法 将45例先后行常规剂量和低剂量盆腔CT检查患者的图像纳入研究，共获得3组图像：A组为常规剂量图像，采用机器默认的滤波反投影重建（FBP）；B组为低剂量图像，采用ASIR，并分别按不同ASIR权重值分为B₁组（ASIR 0）和 B₂组（ASIR 50%）。由两位放射专家对3组图像质量进行评价。结果 B组的容积CT剂量指数（CTDI_vol）、剂量长度乘积（DLP）和有效剂量（E）均显著低于A组（t=12.30、12.10、12.15，P<0.05）。与A、B₂组相比，B₁组的影像噪声（SD）值增加（t=9.14、8.95，P<0.05），而主观图像质量评分、信噪比（SNR）和对比噪声比（CNR）显著降低（t=8.72、10.62、11.83和8.40、9.55、11.42，P<0.05）。A组与B₂组差异无统计学意义。结论 应用自动管电流调制技术和ASIR 50%重建进行成人盆腔CT扫描可以明显降低辐射剂量而不降低图像质量。

Pilot application of statistical iterative reconstruction and automatic tube current modulation in adult low-dose pelvic CT

Objective To investigate the feasibility of reducing the radiation dose in adult pelvic CT using automatic tube current modulation(ATCM) and adaptive statistical iterative reconstruction(ASIR). Methods Totally 45 patients who underwent routine and low-dose pelvic CT examination were enrolled in our study. Three groups of images were acquired: group A (routine scan with FBP reconstruction);group B₁(low-dose with ASIR0) and group B₂(low-dose with ASIR50%). The scores of image quality was abtained by two radiologists. Results The CTDI_vol, DLP and E of group B were significantly reduced respectively(t=12.30, 12.10, 12.15, P<0.05) compared with group A.Group B₁ had higher noise(t=9.14, 8.95, P<0.05)and lower score, SNR and CNR(t=8.72, 10.62, 11.83 and 8.40, 9.55, 11.42, P<0.05)than the others. And there was no difference in image quality between group A and group B₂. Conclusions Using automatic tube current modulation and adaptive statistical iterative reconstruction could significantly reduce the noise but keep the image quality in adult pelvic CT examination.