【摘要】 目的 探讨低kVp技术在下肢CT血管造影（CT angiography,CTA）低剂量扫描的可行性。方法 选取下肢CTA检查病例98例,实验组50例,对照组48例。实验组使用低kVp 90,对照组使用常规kVp 120。记录2组病例扫描时机器自动显示的扫描长度（scan length,L）、容积CT剂量指数(volume computed tomography dose index,CTDI_vol)及剂量长度乘积（dose length product,DLP）,计算有效剂量E值（effective dose,E）。测量并计算L3椎体水平图像信噪比（signal noise ratio,SNR）、对比噪声比（contrast noise ratio,CNR）以客观评价图像质量;双盲法主观评价下肢动脉后重组图像质量并给予优、良、差分级。对L、CTDI_vol、DLP、E值、SNR及CNR进行t检验,主观图像质量评价采用χ²检验。结果 实验组和对照组L分别为（1 026.5±48.3） mm和（1 025.3±57.0）mm,2组比较无统计学差异（P=0.907）。实验组和对照组的CTDI_vol分别为（7.6±0） mGy和（17.6±0）mGy,DLP为（780.2±36.7） mGy/cm和（1 804.5±100.4） mGy/cm,E值为（14.8±0.7） mSv和（34.3±1.9） mSv,2组比较均有统计学差异（P<0.0001）,实验组比对照组均降低56.8%。实验组和对照组SNR分别为46.8±14.9和35.9±10.7（P<0.0001）,CNR分别为39.4±13.7和31.1±10.1（P=0.001）,2组比较有统计学差异,实验组比对照组高。实验组和对照组的图像质量主观评判诊断满意率均达100%,统计学比较无差异。结论 下肢CTA低kVp扫描技术可以较大幅度降低辐射剂量,且不影响图像质量,值得在临床推广应用。更多还原

【Abstract】 Objective To investigate the possibility of lower kVp technique on lower limb CT angiography(CTA).Methods 98cases of lower limb CTA examination were included in the study and divided into the study group(n=50) and contrast group(n=48).90 kVp of low-dose scan was used in the study group while 120 kVp of routine-dose in the contrast group.The scan length(L),volume computed tomography dose index(CTDIvol) and dose length product(DLP) automatically displayed on machine for all cases were respectively recorded and the effective dose(E) was calculated while scanning.The image quality was objectively evaluated by signal to noise ratio(SNR) and contrast to noise ratio(CNR) of tissues measured calculated in the level of lumbar 3.The image quality of post-processing on lower limb arteries was subjectively judged by double blind method and classified into three scale of excellent,good and poor.The results of L,CTDIvol,DLP,E,SNR and CNR between two groups were compared by t test and the subjective judgement of image quality by χ~2 test.Results The L value of study and contrast group was(1026.5±48.3) mm and(1025.3±57.0) mm,and it had no statistical difference in two groups(P=0.907).The CTDIvol,of study and contrast group was respectively(7.6±0) mGy and(17.6±0) mGy,DLP was(780.2±36.7) mGy/cm and(1804.5±100.4) mGy/cm,E value was(14.8±0.7) mSv and(34.3±1.9) mSv,respectively.They all had statistical difference in two groups(P<0.0001),and those of the study group reduced 56.8% than the contrast group.The SNR of study and contrast group was(46.8±14.9) and(35.9±10.7)(P<0.0001),and CNR was(39.4 ± 13.7) and(31.1 ±10.1)(P=0.0001),respectively.It had statistical difference in two groups,and the SNR and CNR of study group were higher than that of the contrast group.On subjective judgment of image quality,the satisfaction rate of two groups was both100.00%,and it had no statistical significance.Conclusion The lower limb CTA using low kVp technique can obviously reduce radiation dose.It has no influence on image quality and has some value in clinical application.更多还原