头颅CT平扫100kV结合SAFIRE技术的临床应用

The Application of SAFIRE Technique in Head CT Scan with Low Radiation Dose

目的探讨第二代双源CT头颅100kV平扫联合应用迭代算法原始数据域迭代重建（SAFIRE）的可行性。方法60例头颅平扫的患者，分为常规剂量120kV组30例和100kV低剂量组30例，其他扫描参数相同。机器自动生成滤波反投影（FBP）图，100kV组再行SAFIRE1～5重建。图像质量评分采用5分法，颅底伪影的评价采用4级。对两组图像质量图像质量主观评分、颅底伪影的评价，平均CT值、噪声、信噪比（SNR）、对比噪声比（CNR）、辐射剂量CT剂量加权指数（CTDIv01）、剂量长度乘积（DLP）、有效剂量（ED）及SAFIRE S1～5重建进行对比分析。结果100kV低剂量组ED较常规剂量120kV组下降18％。两组的噪声、SNR、CNR、图像质量及颅底伪影主观评分均有统计学差异（P〈0．05），而平均cT值无统计学意义（P〉0．05）。SAFIRE1～5重建后，100kV组FBP、S1～5与120kV组FBP比较噪声、SNR及CNR差异有统计学意义，图像质量及颅底伪影主观评分差异无统计学意义（P〉0．05），以s3图像质量评分最高。100kV组噪声为s5最低，且为除S4和s5之间无统计学差异之外，其他各组之间均有统计学差异。结论头颅CT平扫100kV联合SAFIRE重建技术在降低辐射剂量的同时能保证图像质量，以SAFIRE3图像质量评分最高。

Objective To evaluate the feasibility of the head CT plain scan of 100 kV with SAFIRE reconstruction tech- nique of the new dual source. Methods The 60 consecutive patients were performed the plain CT scan of head and divid- ed into two groups which were 30 cases in standard dose 120 kV group and 30 in the low dose 100 kV group. The two groups were all set as following scanning parameters ： tube current 320 mAs, opening the CARE Dose 4D, collimator 128 x 0.6 mm and cerebral window（ 100, 30 HU）. The data were reconstructed to obtain FBP image series with 10-ram section thickness using B30f reconstruction kernel. In addition, 100 kVgroup was reconstructed using SAFIRE reconstruction at 5 strengths. The CT value and CT value of the standard deviation in white matter were measured in ROIs （0.3 x 0.3 cm2 ） in a homogeneous part of the eentrum semiovaJe. The image quality score was accepted with 5 points, the assessment of skull base artifact was 4 strengths. The differences were compared between the two groups in image quality （the subjective sco- ring of image quality and skull base artifact, the mean CT value, noise, signal to noise ratio and contrast to noise ratio）and effective dose and SAFIRE S1 -5. Results Low dose acquisitions were obtained with average 18% dose reduction. There was statistical significance difference in the noise, signal to noise ratio, contrast to noise ratio, the subjective scoring of image quality and skull base artifact between the two groups （ P 〈 0.05 ） , but the mean CT value has no statistical significance difference （ P 〉 0.05 ）. While the images of FBP were reconstructed with SAFIRE 1 - 5, there was no statistical significance difference in the noise, signal to noise ratio, contrast to noise ratio, the subjective scoring of image quality and skull base ar- tifact between the S1 -5 of 100kVgroup. The highest image quality scores of patients is SAFIRE 3. The lowest noise were $5, and except for S4 and S5, there was statistical significance difference between the two groups （ P 〉 0.05 ）. Conclusion Head CT scan 100 kV with SAFIRE reconstruction technique can reduce the radiation dose at the same time ensure image quality. The highest image quality scores of patients is SAFIRE 3.