自动管电流调制技术对腹部CT图像质量及辐射剂量影响的体模研究
자동관전류조제기술대복부CT도상질량급복사제량영향적체모연구
Application of automatic tube current modulation on image quality and radiation dose at abdominal CT
  • 万方数据
    中华放射学杂志 중화방사학잡지
    Chinese Journal of Radiology
    2013年 7期 648-653 ,共6页

    王倩%赵心明%宋俊峰%郭宁%朱颖%刘建新%綦维维%武靖%梁媛

    왕천%조심명%송준봉%곽저%주영%류건신%기유유%무정%량원

    体层摄影术,X线计算机%辐射剂量%腹部%体模 體層攝影術,X線計算機%輻射劑量%腹部%體模
    체층섭영술,X선계산궤%복사제량%복부%체모
    Tomography,X-ray computed%Radiation dosage%Abdomen%Phantom
    目的 探讨应用自动管电流调制技术(ATCM)对腹部CT图像质量及辐射剂量的影响.方法 通过实体测量因病情需要行腹部CT检查的68例体质量指数(BMI)为18 ～ 24 kg/m2的成年男性腹部CT扫描的腹部径向数据,借鉴CTP515辅助测试模体,制作符合国人尺寸的腹部体环,嵌套Catphan600性能测试模型为观察对象,模拟成人腹部CT低、高对比特点用于实验研究.以管电压120 kV,固定管电流450 mA组为对照组；相同管电压条件下,自动管电流技术组为实验组,其中噪声指数(NI)值设置为4 ～ 20,共14组,管电流范围10～ 450 mA.对模型进行扫描.测量Catphan600模体中心均质区域CT值,验证模型对X线衰减的等效性.记录每组扫描方案的辐射剂量指标容积CT剂量指数(CTD Ivol)、个体化剂量估计值(SSDE)、剂量长度积(DLP)、有效剂量(ED)及图像质量客观评价指标图像噪声值(SD)、对比噪声比(CNR).同时由3名分别来自不同医院有5年以上工作经验的腹部诊断医师对Catphan600模体中的CTP515低对比目标显示程度(LCD)模块及CTP528高对比目标显示程度(HCD)模块进行独立主观评价.对NI值与SDb、CNR、CTDIvol、DLP间的相关性采用Pearson相关分析,与LCD模块评分间相关性采用Spearman秩相关分析.不同NI组间SD、CNR及CTDIvol值与对照组的比较采用t检验.LCD和HCD评分的组内比较采用Kruskal-Wallis秩检验,组间差异采用Mann-Whitney U Test秩检验.3名放射科医师主观评价结果的一致性检验采用Kappa分析.结果 实测人体正常肝脏组织CT值为(52.8 ±9.1)HU,腹部模体中心区域平均CT值为(50.8±1.0) HU,两者差异无统计学意义(t=0.31,P＞0.05),偏差程度为4.9％.此模型与成人腹部对X线衰减具有较好的等效性.所有辐射剂量指标均随NI值增大而降低,NI值增加1个单位,辐射剂量指标CTDlvol、SSDE、DLP和ED值分别平均下降1.23 mGy、2.03 mGy、13.20 mGy·cm、0.20 mSv.NI值与图像质量主、客观评价指标及辐射剂量指标间呈高度线性相关(r=0.871～0.982,P值均＜0.05).实验组NI =4 ～7组与对照组间SD、CNR差异均无统计学意义(t值分别为-1.63 ～-0.17,0.03 ～1.12,P值均＞0.05).实验组NI=4～ 10组与对照组间LCD评分差异均无统计学意义(Z值为-1.637 ～0.000,P值均＞0.05).实验组NI =4 ～ 13组与对照组间HCD得分差异均无统计学意义(Z值为-1.423 ～0.000,P值均＞0.05).3名医师对LCD、HCD评分的Kappa一致性检验结果分别为0.743、0.795.结论 在腹部CT扫描中应用自动管电流调制技术可确保图像质量,同时降低辐射剂量.
    목적 탐토응용자동관전류조제기술(ATCM)대복부CT도상질량급복사제량적영향.방법 통과실체측량인병정수요행복부CT검사적68례체질량지수(BMI)위18 ～ 24 kg/m2적성년남성복부CT소묘적복부경향수거,차감CTP515보조측시모체,제작부합국인척촌적복부체배,감투Catphan600성능측시모형위관찰대상,모의성인복부CT저、고대비특점용우실험연구.이관전압120 kV,고정관전류450 mA조위대조조；상동관전압조건하,자동관전류기술조위실험조,기중조성지수(NI)치설치위4 ～ 20,공14조,관전류범위10～ 450 mA.대모형진행소묘.측량Catphan600모체중심균질구역CT치,험증모형대X선쇠감적등효성.기록매조소묘방안적복사제량지표용적CT제량지수(CTD Ivol)、개체화제량고계치(SSDE)、제량장도적(DLP)、유효제량(ED)급도상질량객관평개지표도상조성치(SD)、대비조성비(CNR).동시유3명분별래자불동의원유5년이상공작경험적복부진단의사대Catphan600모체중적CTP515저대비목표현시정도(LCD)모괴급CTP528고대비목표현시정도(HCD)모괴진행독립주관평개.대NI치여SDb、CNR、CTDIvol、DLP간적상관성채용Pearson상관분석,여LCD모괴평분간상관성채용Spearman질상관분석.불동NI조간SD、CNR급CTDIvol치여대조조적비교채용t검험.LCD화HCD평분적조내비교채용Kruskal-Wallis질검험,조간차이채용Mann-Whitney U Test질검험.3명방사과의사주관평개결과적일치성검험채용Kappa분석.결과 실측인체정상간장조직CT치위(52.8 ±9.1)HU,복부모체중심구역평균CT치위(50.8±1.0) HU,량자차이무통계학의의(t=0.31,P＞0.05),편차정도위4.9％.차모형여성인복부대X선쇠감구유교호적등효성.소유복사제량지표균수NI치증대이강저,NI치증가1개단위,복사제량지표CTDlvol、SSDE、DLP화ED치분별평균하강1.23 mGy、2.03 mGy、13.20 mGy·cm、0.20 mSv.NI치여도상질량주、객관평개지표급복사제량지표간정고도선성상관(r=0.871～0.982,P치균＜0.05).실험조NI =4 ～7조여대조조간SD、CNR차이균무통계학의의(t치분별위-1.63 ～-0.17,0.03 ～1.12,P치균＞0.05).실험조NI=4～ 10조여대조조간LCD평분차이균무통계학의의(Z치위-1.637 ～0.000,P치균＞0.05).실험조NI =4 ～ 13조여대조조간HCD득분차이균무통계학의의(Z치위-1.423 ～0.000,P치균＞0.05).3명의사대LCD、HCD평분적Kappa일치성검험결과분별위0.743、0.795.결론 재복부CT소묘중응용자동관전류조제기술가학보도상질량,동시강저복사제량.
    Objective To investigate the effect of automatic tube current modulation (ATCM) on image quality and radiation dose for abdominal CT.Methods An abdomen-equivalent tissue model in the present study was developed,by referring to the CTP515 auxiliary performance testing model made by the internationally recognized Phantom Laboratory,in conjunction with the real data from 68 Chinese male subjects with BMI between 18 to 24 kg/cm2 (subjects with fatty liver,cirrhosis,intraperitoneal huge tumor,ascites or pleural effusion or who were under 18 years old were excluded).Catphan600 performance served as observation object,and simulating adult abdominal CT low and high contrast characteristics to research.Control groups were scanned with CT protocol at fixed 120 kV,450 mA and experimental group were scanned with the same tube voltage and variable current range from 10 to 450 mA (NI value:4 to 20),respectively.CT value was measured by homogeneous area in the center of Catphan600 to verify the phantom for X-ray attenuation of equivalence.CT dose index (CTDIvol),size-specific dose estimates (SSDE),dose length product (DLP),image noise (SD) and contrast to noise ratio (CNR) were recorded and measured.Fifteen mm diameter low-contrast detectability in CTP515 and high-contrast detectability in CTP528 at Catphan600 were evaluated independently by 3 doctors working in abdominal diagnosis for more than five years from three hospitals in a five-point scale.The correlation between NI value and objective,subjective evaluating indicator of image quality and radiation dose were analyzed,and SD,CNR and LCD,HCD scores in different NI group and those in control group were compared with parameter and nonparametric rank sum test.The differences of SD,CNR and CTDIvol scores between NI group and control group were compared with t test.Kruskal-Wallis test was used for intra-group comparison of LCD and HCD scores,Mann-Whiteney U Test for inter-group and Kappa analysis for consistency check of the subjective evaluation result of the 3 radiologists.Results No significant difference was found between the CT value of ROI in catphan 600 central area [(50.8 ± 1.0) HU] scanned under various NI and that of the normal liver tissue [(52.8 ± 9.1) HU] obtained from 68 Chinese male subjects(t =0.31,P ＞ 0.05),with a deviation degree of 4.9％.This phantom was equivalent to adult abdomen for X-ray attenuation.One unit increase in NI was associated with 1.23 mGy,2.03 mGy,13.20 mGy · cm,0.20 mSv decrease in CTDIvoI,SSDE,DLP and ED respectively.NI and objective,subjective evaluating indicator of image quality and radiation dose was highly linear correlated (r =0.871 to 0.982,P ＜ 0.05).There were no significant differences in SD,CNR betweenNIgroup4 to 7 and the control group(t =-1.63 to-0.17,0.03 to 1.12,P ＞0.05).No significant differences were found in LCD scores between NI group 4 to 10 and the control group (Z =-1.637 to 0.000,P ＞ 0.05).And the HCD scores between NI group 4 to 13 and the control group(Z =-1.423 to 0.000,P ＞ 0.05) were not significantly different either.The consistency check result of Kappa analysis of the 3 doctors' LCD,HCD evaluation was 0.743 and 0.795.Conclusion Application of the ATCM technique in abdomen CT can reduce the radiation dose while ensuring the image quality.
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