应用模拟低剂量法行新生儿头颅CT扫描(可编辑)
应用模拟低剂量法行新生儿头颅CT扫描
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应用模拟低剂量法行新生儿头颅CT扫描刘碉彭芸李剑颖曾津津张祺丰(影像技术学(【摘要】目的评估降低扫描剂量对新生儿头颅“层MSCT图像的影响,计算最低剂量。方法选择57例颅内出血患儿进行MSCT扫描,获得每例患儿后颅窝、基底节区及半卵圆中心3个层面实际扫描原始图像17l幅。应用噪声添加工具,模拟扫描剂量减少25,、40,、50,和70,时的扫描情况,将相对应的不同模拟噪声添加到原始图像上,共获得5组855幅图像。2名放射科医师独立对图像质鼍进行评估,图像
包括图像质革和图像噪声,即诊断接受率评分、图像主观噪声评分及客观噪声指数(noise index,NI)。诊断接受率和图像主观噪声均采用5分制评分。图像噪卢测鼍方法:分别在后颅窝、基底节区及半卵圆中心3个层面的小脑实质、丘脑及放射冠脑白质上放置ROI,测量NI
值,然后计算平均值。应用Kappa法评价2名医师评定结果问的一致性,5}Pe绷,l线性相关分析用于评估NI和诊断接受率评分之间的关系。结果患者原始扫描剂量、模拟剂量分别减少25,、40,、50,、70,时图像诊断接受率评分分别为(4(47 4-0(51)、(3(96?0(33)、(3(21-I-0(45)、(2(92?
O(32)、(1(85 4-0(57)分,主观噪声评分(I(62?o(48)、
(1(99?0(48)、(2(76?o(81)、(3(19?
0(67)、(4(27?0(54)分,NI为1(90?0(19、2(17 4-0(加、
2(44?0(25、2(68?0(28、3(37?0(39。2名医师的诊断接受
率评分呈很好的一致性(K=o(860,P=o(017),图像噪声评分呈中度
一致性(K=
0(630,P=0(022)。NI与诊断接受率评分之间呈正相关性
(r=0(826,P=0(001)。模拟扫描剂量减少40,,即管电流为107 mAs
时,NI是2(44,诊断接受率评分是3(21,符合临床诊断需求。结
论在NI为2(44,模拟扫描剂量减少40,时,可获得能满足临床诊
断的图像。【关键词】婴儿,新生;辐射剂量;体层摄影术,x线计
算机The appHcafion of dose(reduction simulation in neonatal head CT scan UU Yue‘(PENG]run。12 Jian―yiag,舾_7,7G Jin-jin,
ZHANG Qi-feng(’tmaging Center,Belling Children’5 Hospital
彤f妇以to CapitaZ Medical University。Be蚵ng 100045。China
Co盯esponding author:PENG Yun(Email:ppengyun@yahoo(corn
【Abstract】Objective To determine the effects ofdose reduction onmulti-slice spiral CT(MSCT)
of neonatsJ head and a8sess the lowest possible radiation
for acceptable clinical images(Methods Fifty??seven
newborlls suspected intracranial hemorrhage were entered
into the study and underwent MSCT stung(Ori矛nal
images atthree anatomic Ievels(posterior fossa,basal
ganglia,centrum semiovale)were collected and
synthetic noise was added?嬲to simulate dose reductions of 25,。40,,50,and 70,,respectively by
using the noise addition t001(A totsl of 855 image data sets were obtained for the 57 patients(Off,hal and
simulated dose(reduction scan images were analyzed(Image
noise and image quality were assessed by two
independent experienced pediatric radiologists using diagnostic acceptability score,subjective image noise
score on a5-point scale and objective noise index(Image
noise Was measured by respectively placing region
of interest(ROI)at cerebellum(thalamus and coFona radiata of 3different slices(And the noise index and
mean value was calculated(The degree of inter―observer
concordalice was determined byKappa statistical
analysis(The Spearman ststistical correlations between the noise index and diagnostic acceptability score
were p眦fometL Results On the images of original dose and simulated dose reductions of 25,,40,,50,and 70,(the
diagnostic acceptability Was 4(47?0(5l,3(96 4-0(33,3(2l
4-0(45,2(92 4-0(32,and 1(85 4-0(57(respectively。the
subjective image sco陀s were 1(62 4-0(48。1(99 4-o(48,
2(76 4-0(8l,3(19 4-0(67(and 4(27 4-0(54。respectively,
the noise index were 1(90 4-0(19,2(17 4-0(20(2(44?
O(25,2(68?0(28,and 3(37-t-0(39,respectively(ne
two radiologists had good interobserver agreement
DOI:10(3760,cnm(j(issn(1005-1201(2009(07(005
基金项目:北京科技新譬资助项目(2007B-008)
作者单位:100045首都医科大学附属北京儿童医院影像中心(刘
明、彭芸、曾津津、张棋丰);GE中国cT影像研究室(李剑颖)
通信作者:彭芸(Email:ppengyun@yahoo(conl
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for diagnostic acceptability(K=0(860,P=O(017)and
forimage noise scoring(K=0(630,P=0(022)(There was significant statistical correlation between image noise index and diagnostic acceptability(r=
O(826(P=0(001)(At 40,dose reduction tothe standard protoc01(the noise index惴2(44 and the
image qualitv score wa8 3(21 which were considered clinically acceptable(Condusion The study revealed
that acceptable images could be obtained with rlle[1ll
noise index of 2(44 and 40,dose reduction(【Key words】Infant,
newborn;Radiation dosage;Tomagraphy,X-my computed
颅内出血是新生儿常见的颅内疾患。发现病变,并对其进行准确定位、定性及定量,对于及时治疗、挽救患儿生命具有重要临床价值。64层MSCT
已经成为婴幼儿疾病检查的重要手段,与普通x线检查相比,放射剂量较高为其缺点。目前尚无一致的头颅CT扫描设置,仅有少数关于成人及儿童较低剂量头颅CT研究报道。本研究旨在应用模拟低剂量法观察不同管电流对新生儿头颅CT图像质量的影响,探讨新生儿低剂量头颅CT扫描的可行性。资料与方法1(一般资料:搜集2006年12月至2007年3月期间就诊于北京儿童医院的57例颅内出血新
生儿,男35例,女22例,年龄为出生后2 h―1个