智能最佳管电压技术对胸部CT辐射剂量和图像质量的影响

目的：分析智能最佳管电压（CARE kV）技术在胸部 CT 平扫中降低辐射剂量和减少图像伪影的应用价值。方法将210例胸部 CT 平扫患者按扫描时间分为 A、B、C 组，每组70例。所有患者均开启智能毫安技术（CARE Dose 4D）模式，A 组采用120 kV、B 组采用100 kV、C 组采用 CARE kV 技术。使用 PACS 工作站进行图像质量主观评价，测量胸廓入口层面脊柱旁肌肉、肺动脉干层面及右下肺静脉层面的降主动脉 CT 值、噪声等，记录扫描参数等。对组间图像质量、辐射剂量等进行统计学分析。结果 C组扫描时自动选择管电压及管电流，其中包括13例100 kV、47例120 kV、10例140 kV。B 组与 A 组比较，有效毫安秒（the effective mAs）、CT 容积剂量指数（CTDIvol）、有效吸收剂量（ED）分别降低10.35%、46.69%、46.26%；C 组与 A 组比较，分别降低35.08%、35.34%、33.48%，组间的差异均有统计学意义（ P <0.05）。胸廓入口层面组间两两比较，C 组和 A 组间的噪声（ SD）、信噪比（SNR）、图像质量评分差异无统计学意义；C 组和 B 组比较，C 组的 SD 显著低于 B 组，而 SNR 和图像质量评分显著高于 B 组，差异均有统计学意义（P <0.05）。C 组的条状伪影及伪影严重程度明显少于（轻于）A 组和 B 组，图像质量显著优于低剂量 B 组。中下肺层面图像质量评分组间差异无统计学意义（P >0.05）。结论 CARE kV 技术能够根据患者体型和解剖部位自动地选择管电压和调整管电流，提高工作效率，在显著降低胸部 CT 平扫辐射剂量的同时，可以有效地降低胸廓入口层面的噪声，减少图像伪影，改善图像质量。

Impaction of CARE kV technique on radiation dose and image quality of chest CT

Objective To analyze the application value of CARE kV technique in decreasing the radiation dose and reducing the im-age artifacts in chest CT scan. Methods 210 cases of patients with chest CT scan were equally divided into three groups according to the scan time,with CARE Dose 4D mode for all groups and group A using 120 kV,group B 100 kV,group C CARE kV. The image quality was subjectively evaluated by PACS workstation,and the CT value and noise were measured in the paraspinal muscles at the level of thoracic in-let,and in the descending aorta at the level of pulmonary trunk and right pulmonary vein. The scan parameters were recorded,and the radia-tion dose and image quality among the three groups were statistically analyzed. Results In group C,the scanning tube voltage and tube cur-rent were automatically selected,including 13 cases of 100 kV,47 cases of 120 kV and 10 cases of 140 kV. The effective mAs,CT dose in-dex volume,effective absorbed dose in group B decreased 10. 35% ,46. 69% ,46. 26% ,respectively,when compared with those of group A. Similarly,in comparison with group A,the effective mAs,CT dose index volume,effective absorbed dose in group C decreased 35. 08% , 35. 34% ,33. 48% ,respectively,and these differences between group B and A,group C and A were statistically significant(P < 0. 05). In the thoracic inlet level,differences of the CT noise,signal noise ratio and image quality score between group C and A were not significant, but when compared with group B,the CT noise was significantly lower and the signal noise ratio and image quality score were significantly higher in group C(P < 0. 05). Streak artifacts and severity of artifacts in group C were significantly less than those in group A and B,and its image quality was significantly better than that in group B with low radiation dose. There was no statistically significant difference in the image quality scores in middle and lower pulmonary level among the three groups(P > 0. 05). Conclusion Application of CARE kV technique would be helpful and effective to select optimum scanning tube voltage and adjust the tube current automatically depending on the body size and anatomical regions of patients,which can significantly reduce the radiation dose of chest CT scan and the noise and image artifacts at the thoracic inlet level to improve image quality.