应用80kV管电压降低主动脉CT造影射线剂量初探

目的 探讨80kV管电压256层螺旋CT主动脉造影降低射线剂量的可行性。方法 对62例疑似主动脉疾病的患者进行主动脉CT造影成像,分为常规管电压扫描组(120kV扫描组)和低管电压扫描组(80kV扫描组),每组31例。然后对两组图像信号噪声比、对比度噪声比和有效剂量进行评估。结果 120与80kV2个扫描组的图像信号噪声比分别为(35.92±5.04)和(33.95±8.30),对比度噪声比分别为(30.32±4.78)和(28.71±7.96),差异均无统计学意义(t =1.131、0.964, P >0.05)。而二组的有效剂量分别为(14.28±0.96)和(9.72±0.81)mSv,差异有统计学意义 (t =20.12, P <0.001)。 结论 同120kV管电压比较,80kV管电压主动脉CT造影在没有降低图像质量的情况下,射线剂量降低约31.9%,同时降低造影剂剂量50%。

Preliminary research of reducing radiation dose in aortic CT angiography with 80 kV tube kilovoltage

Objective To evaluate the feasibility of 80 kV tube kilovoltage in aortic artery CT angiography with 256-slice CT. Methods A total of 62 patients undergoing aortic artery CTA were enrolled into this study and divided into conventional tube kilovoltage (120 kV, n =31) and low tube kilovoltage (80 kV, n= 31). The signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), volume CT dose index (CTDI_vol) and effective dose (E) were evaluated, respectively. Results The mean image SNR was (35.92±5.04) and (33.95±8.30) for conventional tube kilovoltage and low tube kilovoltage, respectively, with no significant difference (t =1.131, P= 0.263). The mean image CNR was (30.32±4.78) and (28.71±7.96) for conventional tube kilovoltage and low tube kilovoltage, respectively, with no significant difference (t =0.964, P= 0.339). The average effective dose (E) was (14.28±0.96)mSv and (9.72±0.81)mSv for conventional tube kilovoltage and low tube kilovoltage, respectively, with significant difference (t =20.12, P <0.001). Conclusions 80 kV tube kilovoltage aortic artery CTA can reduce radiation dose by 31.9%, and contrast dose 50%,and maintain image quality compared with 120 kV tube kilovoltage.