CareDose 4D联合Care kV对CT肺部磨玻璃密度结节图像质量影响的体模研究

目的 探讨CareDose 4D联合Care kV对CT肺部磨玻璃密度结节（ground glass nodule，GGN）图像质量和辐射剂量的影响。方法 采用7种低剂量方案对含有6个GGN的胸部仿真体模行CT扫描。方案1采用CareDose 4D+Care kV。方案2、3、4管电压120 kV，管电流分别为30、20、10 mAs。方案5、6、7管电压100 kV，管电流分别为30、20、10 mAs。比较不同方案的图像质量[CT值、对比噪声比（CNR）、噪声值（SD）和主观评分]和有效剂量（E）。结果 各方案GGN的CT值差异无统计学意义（P>0.05）。方案1的SD高于方案2、3、5，低于方案7，而CNR低于方案2、3、5，高于方案7，差异均有统计学意义（t=13.020、9.560、8.120、-5.720、-7.849、-5.192、-4.130、1.361，P<0.05）。方案1的SD、CNR与方案4、6差异均无统计学意义（P>0.05）。方案1、2、3、5、6各GGN的主观评分均≥ 3分，方案4、7各有1个GGN的主观评分<3分。方案1的E较方案2、3、5、6分别降低了63.0%、44.4%、38.8%、9.1%。结论 CareDose 4D联合Care kV在低剂量肺部CT扫描中，可保证GGN的图像质量，有效降低辐射剂量。

Phantom study of the influence of CareDose 4D and Care kV on CT pulmonary ground glass nodule with respect to image quality and radiation dose

Objective To investigate the effect of CareDose 4D combined with Care kV on CT pulmonary ground glass nodule (GGN) with respect to quality and radiation dose. Methods The thoracic model containing 6 GGN was performed by using 7 low-dose schemes. The CareDose 4D + Care kV was adopted in scheme 1. In schemes 2, 3 and 4, the tube voltage was 120 kV, and the tube current 30, 20 and 10 mAs respectively. In schemes 5, 6 and 7, the tube voltage was 100 kV, and the tube current was 30, 20 and 10 mAs, respectively. The image quality[CT value, contrast noise ratio (CNR), noise value (SD) and subjective score] and effective dose (E) were compared. Results There was no statistically significant difference in CT value of GGN among different schemes (P>0.05). The SD of scheme 1 was higher than those of schemes 2, 3 and 5, but lower than those f scheme 7, while the CNR of scheme 1 was lower than those of schemes 2, 3 and 5, but higher than that of scheme 7 (t=13.020, 9.560, 8.120, -5.720, -7.849, -5.192, -4.130, 1.361,P<0.05). SD and CNR of scheme 1 were not significantly different from those of scheme 4 and 6 (P>0.05). The subjective scores of each GGN of schemes 1, 2, 3, 5 and 6 was over 3 points, but and the subjective scores of one GGN of each of schemes 4 and 7 were below 3 points. The value E of the scheme 1 was reduced by 63.0%, 44.4%, 38.8%, and 9.1%, compared with the schemes 2, 3, 5 and 6, respectively. Conclusions CareDose 4D combined with Care kV in low-dose lung CT scan can ensure the image quality of GGN and reduce the radiation dose effectively.