低管电压联合管电流自动调节技术降低下肢动脉CTA辐射剂量

Low tube voltage combined with automatic tube current modulation technique for reducing radiation dosage in lower limb CTA

目的探讨低管电压结合管电流自动调节技术实现下肢动脉CTA低剂量扫描的可行性。方法将64例患者分为3组行下肢动脉CTA检查,A组管电压120kV,管电流自动调节范围50~250mA;B组管电压100kV,管电流自动调节范围50~350mA;C组管电压80kV,管电流自动调节范围100~350mA;获得腹主动脉、股动脉及腘动脉CT值、图像噪声、SNR、扫描长度（SL）、容积CT剂量指数（CTDIvol）及剂量长度乘积（DLP）。并对图像质量进行主观评价。结果3组间腹主动脉、股动脉及腘动脉CT值、图像噪声、SNR差异均有统计学意义（P均〈0.05）。3组间SL差异无统计学意义（P〉0.05）,CTDIvol、DLP差异均有统计学意义（P均〈0.05）。A、B、C组图像均可满足诊断要求,主观图像质量评分分别为（2.50±0.51）分、（2.44±0.63）分及（2.41±0.56）分,差异无统计学意义（P〉0.05）。结论低管电压结合管电流自动调节技术,可在获得符合诊断要求图像的同时,降低下肢动脉CTA扫描辐射剂量。

Objective To investigate the possibility of lower dose CTA in lower extremity artery using low kVp combined vcith autgmatic tube current modulation techniques. Methods Sixty-four patients underwent lower extremity artery CTA and were divided into 3 groups （group A, B and C）. The tube voltage and tube current modulation range were 120 kV and 50--250 mA in group A, 100 kV and 50--350 mA in grouop B, 80 kV and 100--350 mA in group C, respectively. The CT value, image noise, SNR, scan length （SL）, volume computed tomography dose index （CTDIvol） and dose length product （DLP） of aorta abdominals, femoral artery and popliteal artery were obtained. And the image quality were evalua- ted subjectively. Results There were significant difference among 3 groups in CT value, image noise, SNR, CTDIvol and DLP （all P〈0.05）. No significant difference was found in SL value （P〉0.05）. All the CTA images were suitable for di- agnosis. The image quality score in group A, B and C was 2.50±0.51, 2.44±0.63 and 2.41±0.56, respectively. No significant difference was found among 3 groups （P〉0.05）. Conclusion Low kVp combined with automatic tube current modulation techniques is helpful to obtain suitable images for diagnosis, meanwhile reduce radiation dose obviously.