目的 在64层螺旋CT(64-MSCT)心脏检查中,通过对不同体重指数(BMI)采用不同管电流的研究,达到均衡控制X线剂量的目的 .方法 实验分2个步骤:(1)连续选取100例(C组)不同BMI拟行64-MSCT冠状动脉造影的患者,使用GE LightSpeed VCT机完成心脏扫描.采用640 mA,120 kV,0.35 s/r,层厚0.625mm,螺距0.22-0.24,选用体部前置滤线器模式,后置过滤器(C2)重建.采像后,在主动脉分出冠状动脉左主干层面的上下3层,分别选取面积相等的感兴趣区(10mm×10 mm)测量图像噪声,取3层CT值的标准差的平均值作为该患者的图像噪声.使用软件拟合患者BMI与噪声的关系,得出线性方程,根据噪声和射线剂量的关系,得到管电流与BMI的对应公式.(2)连续选取100例(L组)拟行64-MSCT冠状动脉造影的患者,先计算其BMI,并选定图像噪声常数27为可接受噪声,根据之前得到的BMI与管电流的对应公式确定mA值,选用心脏前置滤线器模式,开启心电图电流调控,C2重建.其他扫描参数不变,并以相同方法测量图像噪声.(3)应用SPSS 10.0软件分别对第1步、第2步实验得到的BMI、心率、图像质量评分、图像噪声、CT剂量指数(CTDI)、有效剂量(ED)均值进行单因素方差分析.结果 (1)C组BMI 25.08±2.64,图像质量(3.71±0.54)分,噪声24.56±5.03,ED(17.63±1.68)mSv.拟合不同BMI和噪声得出曲线回归公式,根据射线剂量和噪声关系,得出电流随BMI变化的关系:常规管电流(FmA)×[(k1×BMI+c1)/Ina]2,FmA=640 mA,常数(k1)=1.033,截距(c1)=-3.2,噪声(Ina)=27.(2)L组BMI25.07±2.91,图像质量(3.69±0.53)分,噪声26.61±3.44,管电流(469.95±113.45)mA,ED(9.08±2.25)msv.L组噪声高于C组(F=927.390,P=0.001),但图像质量评分差异无统计学意义(F=0.068,P=0.794).ED均值较C组下降约48%.结论 在64-MSCT心脏成像时,根据不同个体的BMI采用不同管电流,再综合应用低剂量技术,可使扫描方案的设计更加合理和个性化,从而达到在保证图像质量不变的前提下均衡控制不同体重指数个体射线剂量的目的 .
目的 在64層螺鏇CT(64-MSCT)心髒檢查中,通過對不同體重指數(BMI)採用不同管電流的研究,達到均衡控製X線劑量的目的 .方法 實驗分2箇步驟:(1)連續選取100例(C組)不同BMI擬行64-MSCT冠狀動脈造影的患者,使用GE LightSpeed VCT機完成心髒掃描.採用640 mA,120 kV,0.35 s/r,層厚0.625mm,螺距0.22-0.24,選用體部前置濾線器模式,後置過濾器(C2)重建.採像後,在主動脈分齣冠狀動脈左主榦層麵的上下3層,分彆選取麵積相等的感興趣區(10mm×10 mm)測量圖像譟聲,取3層CT值的標準差的平均值作為該患者的圖像譟聲.使用軟件擬閤患者BMI與譟聲的關繫,得齣線性方程,根據譟聲和射線劑量的關繫,得到管電流與BMI的對應公式.(2)連續選取100例(L組)擬行64-MSCT冠狀動脈造影的患者,先計算其BMI,併選定圖像譟聲常數27為可接受譟聲,根據之前得到的BMI與管電流的對應公式確定mA值,選用心髒前置濾線器模式,開啟心電圖電流調控,C2重建.其他掃描參數不變,併以相同方法測量圖像譟聲.(3)應用SPSS 10.0軟件分彆對第1步、第2步實驗得到的BMI、心率、圖像質量評分、圖像譟聲、CT劑量指數(CTDI)、有效劑量(ED)均值進行單因素方差分析.結果 (1)C組BMI 25.08±2.64,圖像質量(3.71±0.54)分,譟聲24.56±5.03,ED(17.63±1.68)mSv.擬閤不同BMI和譟聲得齣麯線迴歸公式,根據射線劑量和譟聲關繫,得齣電流隨BMI變化的關繫:常規管電流(FmA)×[(k1×BMI+c1)/Ina]2,FmA=640 mA,常數(k1)=1.033,截距(c1)=-3.2,譟聲(Ina)=27.(2)L組BMI25.07±2.91,圖像質量(3.69±0.53)分,譟聲26.61±3.44,管電流(469.95±113.45)mA,ED(9.08±2.25)msv.L組譟聲高于C組(F=927.390,P=0.001),但圖像質量評分差異無統計學意義(F=0.068,P=0.794).ED均值較C組下降約48%.結論 在64-MSCT心髒成像時,根據不同箇體的BMI採用不同管電流,再綜閤應用低劑量技術,可使掃描方案的設計更加閤理和箇性化,從而達到在保證圖像質量不變的前提下均衡控製不同體重指數箇體射線劑量的目的 .
목적 재64층라선CT(64-MSCT)심장검사중,통과대불동체중지수(BMI)채용불동관전류적연구,체도균형공제X선제량적목적 .방법 실험분2개보취:(1)련속선취100례(C조)불동BMI의행64-MSCT관상동맥조영적환자,사용GE LightSpeed VCT궤완성심장소묘.채용640 mA,120 kV,0.35 s/r,층후0.625mm,라거0.22-0.24,선용체부전치려선기모식,후치과려기(C2)중건.채상후,재주동맥분출관상동맥좌주간층면적상하3층,분별선취면적상등적감흥취구(10mm×10 mm)측량도상조성,취3층CT치적표준차적평균치작위해환자적도상조성.사용연건의합환자BMI여조성적관계,득출선성방정,근거조성화사선제량적관계,득도관전류여BMI적대응공식.(2)련속선취100례(L조)의행64-MSCT관상동맥조영적환자,선계산기BMI,병선정도상조성상수27위가접수조성,근거지전득도적BMI여관전류적대응공식학정mA치,선용심장전치려선기모식,개계심전도전류조공,C2중건.기타소묘삼수불변,병이상동방법측량도상조성.(3)응용SPSS 10.0연건분별대제1보、제2보실험득도적BMI、심솔、도상질량평분、도상조성、CT제량지수(CTDI)、유효제량(ED)균치진행단인소방차분석.결과 (1)C조BMI 25.08±2.64,도상질량(3.71±0.54)분,조성24.56±5.03,ED(17.63±1.68)mSv.의합불동BMI화조성득출곡선회귀공식,근거사선제량화조성관계,득출전류수BMI변화적관계:상규관전류(FmA)×[(k1×BMI+c1)/Ina]2,FmA=640 mA,상수(k1)=1.033,절거(c1)=-3.2,조성(Ina)=27.(2)L조BMI25.07±2.91,도상질량(3.69±0.53)분,조성26.61±3.44,관전류(469.95±113.45)mA,ED(9.08±2.25)msv.L조조성고우C조(F=927.390,P=0.001),단도상질량평분차이무통계학의의(F=0.068,P=0.794).ED균치교C조하강약48%.결론 재64-MSCT심장성상시,근거불동개체적BMI채용불동관전류,재종합응용저제량기술,가사소묘방안적설계경가합리화개성화,종이체도재보증도상질량불변적전제하균형공제불동체중지수개체사선제량적목적 .
Objective To evaluate the robustness of body mass index (BMI) adapted tube current selection method for obtaining consistent image quality in MSCT coronary artery imaging Methods Initially one hundred patients in the control group ( C group) underwent cardiac scans using GE 64-row VCT with standard scan protocol (640 mA, 120 kV, 0.35 see, body bewtie, C2 filter). Noise measurement was obtained for each patient using the average of three consecutive slices in the ascending aorta with ROI of 10 mm×10 mm to establish the relationship between BMI, desired image noise (IN) and required mA. An excel table was established to predict the required mA to achieve a desired IN for each patient with different BMI. A second group of one hundred cardiac patients (L group) was scanned with BMI-aclapted mA from the table to evaluate the practicability of this method. BMI, IN, CT dose index(CTDI),effective dose (ED) were all recorded. Results For the control group of 100 patients, the mean values and standard deviations of image quality score (IQS), BMI, IN and ED were 3.71±0.54, 25.08±2.63, 24.56±5.03 and (17.63±1.68 ) mSv (with range of 15-22 msy). Regression analysis indicated linear relationship between BMI and image noise with fixed mA. Using the relationship between tube current and image noise and noise ratio between large bowtie and cardiac bowtie, the following equation for the required tube current Xma to achieve present image noise of Ins for patient with certain BMI value when using cardiac bowtie could be then obtained: Xma = Fma×( k1 x BMI + c1 )/Ina]2, where Fma = 640 mA, k1 = 1. 033, c1 = - 3.2, Ins = 27 in the study. (2) For the patients in L group, the mean values and standard deviations of IQS, BMI, and IN were 3.69±0.53, 25.07±2.91, and 26.61±3.44, respectively. The average tube current used was (469.95±113.45) mA, depending on patient's BMI values. The average effectively dose was(9.08±2.25) mSv. There was no statistically difference between the two groups in image quality( F= 0.068,P=0.794). Conclusions In 64-MSCT cardiac imaging, the use of BMI dependent tube current selection method, in conjunction with dose reduction techniques, can provide individualized scan protocol to obtain consistent image quality across patient population and to optimize dose delivery to patients.
