膝关节置换术后X射线摄影中不同曝光模式对影像质量和辐射剂量的影响

目的 探讨膝关节置换术（TKA）术后最佳摄影条件及临床应用的可行性。方法 根据不同的曝光方式，分为自动曝光模式组（AEC）、手动曝光模式组（FIXED），以固定kV、依次改变相应mAs的方式，对模体进行曝光，记录各曝光条件下入射剂量（ESD）、剂量曝光指数（DEI）、主观图像质量评价，经统计学分析后得出最优化试验组参数与回顾组进行辐射剂量及主观评价比较。结果 AEC组ESD与kV呈负相关（r=-0.973，P < 0.05），在相同mA条件下，DEI随kV增加呈先减后增的弧线型变化，主观图像质量评价均值为（1.96±0.56），DEI与主观图像评分呈负相关（r=-0.840，P < 0.05）。FIXED组ESD随mAs的增加而成线性增加，呈正相关（r=0.845，P < 0.05），DEI与kV、mAs成正相关（r=0.628、0.674，P < 0.05）。主观图像质量评价均值为（4.33±0.79），与DEI无相关性。选择最优化实验组与回顾组相比，主观图像质量评价分值增加，辐射剂量降低明显。结论 对于膝关节置换假体植入受检患者，采用手动曝光模式，80 kV/1.25~1 mAs、75 kV/2~1 mAs、70 kV/2.5~1.25 mAs、65 kV/3.2~1.6 mAs和60 kV/3.2~2 mAs为最优化区间。

Influence of different exposure modes on image quality and radiation dose after knee replacement surgery X-ray photography

Objective To study the optimal radiographic conditions for patients with knee arthroplasty (TKA) and the feasibility of clinical application. Methods According to the different exposure modes, including automatic exposure control(AEC) or manual exposure mode (FIXED), the human body specimen was exposed at a certain kV and different mA or mAs. The entrance surface dose (ESD)and dose exposure index(DEI)were recorded, and the subjective image quality was assessed. The test group with optimum parameters obtained with statistical analysis were compared with control group in radiation dose and subjective evaluation. Results In AEC group, ESD and kV showed a negative correlation (r=-0.973, P < 0.05). At the same mA, DEI was firstly decreased and then increased with kV increasing. The subjective image quality score was(1.96±0.56). DEI and physician ratings showed negative correlation (r=-0.840, P < 0.05). In FIXED group, ESD increased with the increasing mAs (r=0.845, P < 0.05). DEI and kV,mAs indicated a positive correlation(r=0.845, P < 0.05). The subjective image quality scores was(4.33±0.79) without correlation with DEI. Compared with the control group, the subjective image quality scores of test group increased, and the radiation dose decreased significantly. Conclusion It is optimal using manual exposure mode with 80 kV/1.25-1 mAs,75 kV/2-1 mAs,70 kV/2.5-1.25 mAs,65 kV/3.2-1.6 mAs and 60 kV/3.2-2 mAs for patients with TKA.