摘要
目的:探讨不同辐射剂量、不同等级的滤波反投影算法(FBP)、迭代重建算法(Karl)和深度学习重建算法(DL)对骨密度测量值准确性的影响。方法:使用联影uCT760 CT机,分别采用剂量调制等级3(常规辐射剂量组,ND)和剂量调制等级1(低辐射剂量组,LD)对拟人化欧洲脊柱体模(ESP)进行10次重复扫描。扫描结束后对每次扫描的图像分别采用FBP、Karl(5、7、9级)和DL(1~4级)算法进行图像重建,共获得16组重建图像。在QCT Pro工作站上测量各组图像上L_(1)~L_(3)椎体的骨密度(BMD)值,并计算其与各椎体体模标定值的相对误差(RE);在L_(1)、L_(2)和L_(3)椎体内放置感兴趣区,测量其CT值及SD值,并计算对比噪声比(CNR)。采用独立样本t检验分析分别比较16组图像中BMD测量值与真实值的差异,采用配对样本t检验分析ND组与LD组之间BMD测量值和辐射剂量的差异,采用单因素方差分析比较相同辐射剂量不同重建算法和等级的8组图像之间BMD测量值和CNR的差异。结果:LD组的毫安秒(mAs)、CTDIvol和DLP相较于ND组分别降低了78.41%、78.25%和78.28%,差异均有统计学意义(t=158.692~1699.766,P均<0.001)。不同辐射剂量相同重建算法下,L_(1)、L_(2)和L_(3)的BMD值的差异均无统计学意义(t=-2.006~1.472,P均>0.05);相同辐射剂量下8组重建图像上所测得的L_(1)~L_(3)椎体的BMD值的总体差异均无统计学意义(F=0.485~1.954,P均>0.05);各组图像所测得的BMD值与ESP体模标定值之间的差异均有统计学意义(P均<0.05),RE范围为2.17%~7.44%;相同辐射剂量组内8组重建图像上测得的各椎体CNR的差异均有统计学意义(F=47.883~153.983,P均<0.001)。结论:不同重建算法及相同算法不同等级在不同辐射剂量下对骨密度测量的准确性均无显著影响;选择合适的重建算法及等级可在保证图像质量的前提下有效降低患者的辐射剂量。
Objective:To investigate the effect of different levels of filtered back-projection algorithm(FBP),iterative reconstruction algorithm(Karl)and deep learning reconstruction algorithm(DL)on the accuracy of bone mineral density assessment at different radiation doses.Methods:Using the United Image uCT760 CT scanner,a phantom was scanned at different radiation doses by changing the level of dose modulation technique.The anthropomorphic European Spine Phantom(ESP)was scanned 10 times with dose modulation level 3(conventional radiation dose group,ND)and dose mo-dulation level 1(low radiation dose group,LD),respectively.After scanning,the images of each set were reconstructed using FBP,Karl(level 5,7,9)and DL(level 1~4)algorithms,respectively,and a total of 16 groups of reconstructed images were obtained.The QCT Pro workstation was used to mea-sure the bone mineral density(BMD)of L_(1)~L_(3) vertebral bodies in each set of images and the relative errors(RE)were calculated.Regions of interest were placed in the L_(1),L_(2) and L_(3) vertebrae,and the CT and its SD values were measured to calculate the contrast-to-noise ratio(CNR).The two-sample t-test was used to compare the BMD measurements on 16 groups of images with the true BMD values.The paired t-test was used to analyze the differences in BMD measurements and radiation doses between ND group and LD group.One-way ANOVA was used to compare the differences in BMD measurements and CNR among the 8 groups of images with different reconstruction algorithms and levels at the same radiation dose.Results:The mean of mAs,CTDIvol and DLP in the LD group were reduced by approximately 78.41%,78.25%and 78.28%compared with the ND group,all with statistically significant differences(t=158.692~1699.766,all P<0.001).There were no statistically significant diffe-rences in BMD measurement of L_(1),L_(2) and L_(3) by ESP at different radiation doses and with the same reconstruction algorithm and level(t=-2.006~1.472,all P>0.05).At the same radiation dose,there was no significant difference in BMD values of L_(1)~L_(3) vertebral bodies among the eight groups of reconstructed images(F=0.485~1.954,all P>0.05).The differences in BMD measured in each of the 16 groups compared to the ESP true values were statistically significant(all P<0.05),with an RE range of 2.17%to 7.44%.The differences in CNR values for each vertebra among the 8 groups with the same radiation dose were statistically significant(F=47.883~153.983,all P<0.001).Conclusion:Different reconstruction algorithms and different levels of the same algorithm at different radiation dose levels do not affect the accuracy of BMD measurements.The appropriate selection of reconstruction algorithm and grade can reduce patients’radiation dose while ensuring image quality.
作者
童小雨
刘义军
方鑫
李贝贝
王旭
陈安良
TONG Xiao-yu;LIU Yi-jun;FANG Xin(Department of Radiology,the First Affiliated Hospital of Dalian Medical University,Liaoning 116011,China)
出处
《放射学实践》
CSCD
北大核心
2023年第8期1055-1059,共5页
Radiologic Practice
关键词
图像重建
深度学习
迭代重建
骨密度
辐射剂量
体层摄影术
X线计算机
Image reconstruction
Deep learning
Iterative reconstruction
Bone mineral density
Radiation dose
Tomography,X-ray computed
作者简介
童小雨(1998-),女,四川德阳人,硕士研究生,主要从事CT成像工作;通讯作者:刘义军,E-mail:yijunliu1965@126.com。
