低管电压头颈CTA图像质量与辐射剂量的定量评估

Evaluation of Image Quality and Radiation Dose for Low-tube Voltage Head and Neck CTA

目的：通过尝试直接降低管电压的方法控制辐射剂量,并评价图像质量,探讨其临床应用价值。方法：前瞻性选取2013年9月~2014年7月拟行头颈CTA检查的患者40例,并满足入组条件。患者分为A、B两组。A组患者采用低管电压设置,B组患者采用常规管电压设置。评价两组患者双侧颈动脉客观图像质量（包括CT值、SNR与CNR）与主观图像质量、辐射剂量。P〈0.05认为差异具有统计学意义。结果：A组SNR为11.39±3.80,B组总SNR为12.48±4.48,t=-1.660,P=0.099,差异无统计学意义。A组总对CNR为10.12±3.55,B组总CNR为10.44±4.14,t=-0.485,P=0.628,差异无统计学意义。A、B两组可评估率比较差异无统计学意义（χ2=1.013,P=0.314）。A组有效剂量为2.29 m Sv±0.12 m Sv,B组有效剂量为6.69 m Sv±0.31 m Sv,t=-59.756,P=0.000,差异具有统计学意义。结论：通过降低管电压至80 k V行头颈CTA扫描可以大幅度减低辐射剂量,而图像质量无明显影响,可以进行初步临床应用。

Objective： The purpose of this prospective study was to compare with image quality and radiation dose between low voltage and conventional head and neck CTA protocols. Methods： 40 consecutive patients were prospectively enrolled From September 2013 to July 2013, and satisfy the following conditions. Patients in group A was with low tube voltage settings, patients in group B was with traditional tube voltage settings. Two groups were evaluated for image quality, mean attenuation, noise, signal-to-noise ratio （SNR） and contrast-to-noise （CNR） in carotid artery and radiation dose. A P value below 0.05 was considered to be statistically significant. Results： The mean attenuation, noise, SNR and CNR was no statistically significant for group A versus group B （b 〉 0.05）. The percentage of assessable coronary artery segments was no statistically significant for group B versus group A （χ2 = 1.013, P = 0.314）. The mean effective dose was statistically significant for the group A was 2.29 mSv versus 6.69 mSv for the group B （t = -59.756, P = 0.000）. Conclusion Low tube voltage for head and neck CTA technique could offer assessable image quality and substantially reduced effective radiation dose.