The Clinical Study Of128-slice Spiral CT Low Tube Voltage To Reduce The Radiation Dose In Head Digital Subtraction CT Angiography

Objective: The objective is to evaluate the clinical applicationof the feasibility and value of low tube voltage to reduce the radiation dose bycomparing and analyzing the impact of the low tube voltage(80kV,100kV)withconventional tube voltage (120kV) of the radiation dose and image quality inhead digital subtraction CT angiography (DS-CTA)Methods: All adult patients from2012October to2013March, total of57cases (31male,26females,aged37-85years old:average age is62.4years old)who required head DC-CTA in our hospital,are prospectively selected in ourstudy. The patients are enrolled randomly assigned according to the principle ofdifferent tube voltage group, namely A (80kV), B (100kV), C (120kV),whichare19cases in A group,20cases in B group and C group of18cases.All arebased on the same scanning parameters substantially,we compare and analyzethe radiation dose of three groups of different tube voltage,including CT doseindex (CTDIvol),the dose-length product (DLP), the effective dose (ED),quantitative and qualitative analysis of image quality,For quantitative analysis,itcontains vascular signal intensity(SI), signal-to-noise ratio (SNR) andcontrast-to-noise ratio (CNR);Qualitative analysis is done by two experiencedradiologists using a5evaluation method blinded independent evaluation of theoriginal image,two-dimensional,three-dimensional image quality. We usestatistical analysis:evaluation of single-factor analysis of variance among thethree groups of image radiation dose and CT values,image noise,CNR,SNR difference;using nonparametric rank sum test to compare the images as thesubjective score difference between three groups;Kappa test evaluationconsistency between the two observers.A P-level of <0.05was consideredstatistically significant and k>0.60are good consistency.Results:1.Radiation dose results:Compared with the conventional tubevoltage group C (120kV),the low tube voltage group A,B two groups (80kV,100kV) radiation dose(CTDIvol,DLP,ED)are significantly reduced,Theespecially in the80kV group and the difference was statistically signifycan-ce2.Quantitative image analysis:with the tube voltage reducing reinforcementvalue the blood vessels of the head incease and the differences are statisticallysignificant,at the same time the image noise significantly increase when tubevoltage is reduced,but the differences of CNR and SNR in the patients of thethree groups has no statistical significance.3.Qualitative analysis of imagequality:With the lower tube voltage,the vessel edge sharpness is reduced,whilesmall branch vessels increased, the vein interference increase,but the overallquality of image quality and image differences between the three groups inMIP,MPR,VR three-dimensional image has no statistical significance，and noeffect in diagnosis of cerebral vascular diseases.4.Two observers rated good.ConsistencyConclusion:128-slice spiral CT low tube voltage scanningcan significantly reduce radiation dose in head digital subtraction CTangiography,increased vascular signal intensity, and no significant effect on theimage quality and clinical diagnosis, which has the feasibility in clinicalapplication.