【摘要】：目的：1.探討不同管電壓及周圍結(jié)構(gòu)對(duì)CT值測量的影響。2.評(píng)價(jià)降低管電壓及管電流時(shí)下肢動(dòng)脈CTA檢查的可行性及其對(duì)圖像質(zhì)量和X射線輻射劑量的影響,并在不影響診斷的前提下找出合理的管電壓、管電流組合,以最大限度的降低X線輻射劑量。 材料和方法：1.CT掃描儀的管電壓分別設(shè)定為120、100、80kV,其它掃描參數(shù)不變,分別對(duì)濃度為14mgI/ml的碘對(duì)比劑、醫(yī)用硅膠塊、乳膠塊、生物膠塊及由這幾種物質(zhì)制備的模擬動(dòng)脈硬化血管模型進(jìn)行掃描,測量不同條件下各單一結(jié)構(gòu)掃描的CT值和模型掃描中相應(yīng)的同種物質(zhì)的CT值,評(píng)估不同管電壓及周圍結(jié)構(gòu)對(duì)CT值測量的影響。2.采用16層螺旋CT,收集臨床診斷為ASO的病人30例,隨機(jī)分為3組：組Ⅰ管電壓為100kV,管電流260mA；組Ⅱ管電壓為100kV,管電流210mA；組Ⅲ管電壓為80kV,管電流260mA,以上述掃描條件分別行下肢動(dòng)脈CTA檢查。測量動(dòng)脈管腔內(nèi)CT值、周圍軟組織CT值、背景噪聲,計(jì)算圖像信噪比(SNR)、對(duì)比噪聲比(CNR)、圖像優(yōu)良指數(shù)(FOM),并由兩名有經(jīng)驗(yàn)的放射科醫(yī)生采用雙盲法分別對(duì)圖像質(zhì)量進(jìn)行評(píng)分。 結(jié)果：1.管電壓120kV時(shí)單獨(dú)掃描碘對(duì)比劑、醫(yī)用硅膠塊、乳膠塊、生物膠塊及模型中4種物質(zhì)的CT值分別為(380.63±8.49)HU和(377.03±3.83)HU(P=0.02)、(293.94±17.83)HU和(334.07±5.95)HU(P=0.00)、(-154.64±12.56)HU和(-95.09±26.22)HU(P=0.00)、(-54.66±2.09)HU和(-40.79±6.85)HU(P=0.00)；管電壓100kV時(shí)其CT值分別為(442.97±6.48)HU和(439.77±4.95)HU(P=0.02)、(332.79±6.78)HU和(383.90±6.14)HU(P=0.00)、(-166.2±12.61)HU和(-122.43±27.71)HU(P=0.00)、(-74.28±4.41)HU和(-64.74±10.65)HU(P=0.00)；管電壓80kV時(shí)其CT值分別為(557.74±5.61)HU和(556.80±9.70)HU(P=0.62)、(426.71±8.70)HU和(489.90±12.31)HU(P=0.00)、(-202.30±27.10)HU和(-139.57±26.77)HU(P=0.00)、(-87.64±4.77)HU和(-79.81±14.64)HU(P=0.00)。當(dāng)管電壓由高降低時(shí),高密度物質(zhì)CT值升高,低密度物質(zhì)CT值降低。周圍結(jié)構(gòu)對(duì)CT值測量亦有影響,物質(zhì)之間的密度差別越大,其CT值所受影響越大。2.組Ⅲ動(dòng)脈管腔內(nèi)CT值高于組Ⅰ、組Ⅱ,差異有統(tǒng)計(jì)學(xué)意義(P0.05),組Ⅰ與組Ⅱ間差異無統(tǒng)計(jì)學(xué)意義(P0.05)。體厚較厚區(qū)域組Ⅲ軟組織CT值低于組Ⅰ、組Ⅱ,差異有統(tǒng)計(jì)學(xué)意義(P0.05),組Ⅰ與組Ⅱ間差異無統(tǒng)計(jì)學(xué)意義(P0.05)；體厚較薄區(qū)域三組間軟組織CT值差異均無統(tǒng)計(jì)學(xué)意義(P0.05)。三組間背景噪聲差異有統(tǒng)計(jì)學(xué)意義(P0.05),組Ⅲ背景噪聲最大。三組間血管SNR、CNR及圖像質(zhì)量主觀評(píng)分差異均無統(tǒng)計(jì)學(xué)意義(P0.05),而體厚較厚區(qū)域軟組織SNR的差異有統(tǒng)計(jì)學(xué)意義(P0.05)。三組管電壓、管電流組合條件下CTDIvol、 DLP、ED分別為5.41、635.00±11.25、12.07±0.24；4.02、488.89+25.94、9.29±0.55；2.63、304.56±9.50、5.79±0.20,差異均有統(tǒng)計(jì)學(xué)意義(P=0.00)。三組間FOM差異有統(tǒng)計(jì)學(xué)意義(P0.05),組Ⅲ(管電壓80kV,管電流260mA)時(shí)FOM最大。 結(jié)論：1.管電壓改變時(shí)物質(zhì)的CT值會(huì)發(fā)生改變,同時(shí)周圍結(jié)構(gòu)也會(huì)影響到CT值,但周圍結(jié)構(gòu)對(duì)碘對(duì)比劑的CT值影響不大。2.在進(jìn)行CT值的定量研究時(shí)要關(guān)注管電壓的改變以及周圍結(jié)構(gòu)對(duì)CT值的影響。3.降低管電壓可以較明顯的降低X線輻射劑量。4.X線輻射劑量的降低對(duì)血管SNR無影響,但會(huì)影響到腹盆部軟組織的SNR。5.推薦80kV和260mA的組合作為下肢動(dòng)脈CTA檢查的常規(guī)掃描條件。
[Abstract]:Purpose: 1. To investigate the effect of different tube voltage and surrounding structure on the measurement of CT value. To evaluate the feasibility of CTA examination of lower limb artery and its effect on image quality and X-ray radiation dose in reducing tube voltage and tube current, and to find out reasonable tube voltage and tube current combination without affecting diagnosis, so as to minimize X-ray radiation dose. Materials and Methods: 1. The tube voltage of CT scanner was set to 120, 100, 80kV respectively, and the other scanning parameters remained unchanged. The iodine contrast agent, medical silica gel block, latex block, bio-gel block and the simulated arteriosclerosis vascular model prepared by these substances were respectively applied to the iodine contrast agent with concentration of 14mgI/ ml. scanning, measuring CT value of each single structure scan under different conditions and CT value of corresponding same substance in model scanning, evaluating the effect of different tube voltage and surrounding structure on CT value measurement. 2. 30 patients with ASO were collected by 16-slice spiral CT, and randomly divided into 3 groups: group 鈪，

本文編號(hào)：2290713