个体化低辐射剂量胸部增强CT成像的模体与临床研究

Feasibility of individualized low radiation dose chest enhanced CT imaging:phantom and clinical study

目的探讨自动预置技术(Auto-prescription)和全视野器官剂量调制(ODM_(full))技术相结合对胸部增强CT图像质量和辐射剂量的影响,探究个体化低辐射剂量胸部增强CT成像的可行性。方法模体研究:分别采用4种扫描模式(A组,120 kVp+Smart-mA;B组,120 kVp+Smart-mA+ODM_(full);C组,Auto-prescription+Smart-mA;D组,Auto-prescription+Smart-mA+ODM_(full))对PH-75模体(TR-I和TR-J)进行扫描,每组均重建后置40%~80%ASIR-V(间隔20%)图像,记为A_(1-3)~D_(1-3),评估图像质量和辐射剂量,获取最佳成像模式。临床研究:收集大连医科大学附属第一医院2021年11月至2022年7月临床已确诊肺内病变(肿块或实性结节)患者35例,且3个月内需进行2次胸部CT增强,第一次增强CT参数同模体研究中A_(1)组,记为A患者;第二次增强CT检查采用模体研究中D2组参数,记为D_(患者)。比较2组图像信噪比、对比信噪比、主观评分及病变的影像学表现。结果模体研究:D组辐射剂量最低;对于2种尺寸模体,将A_(1)作为对照组进行两两比较时,噪声值(SD):B_(1)、C_(1)、D_(2)组图像SD与A_(1)差异无统计学意义,D1组SD高于A_(1),余各组SD低于A_(1)(F=10.77、122.50,P<0.05);对比噪声比(CNR):B1组图像CNR与A_(1)差异无统计学意义,其余各组CNR均高于A_(1)(F=136.20、30.21,P<0.05);主观评分:A_(2)、C_(2)、D_(2)组图像主观评分与A_(1)差异无统计学意义;余各组均低于A_(1)(H=52.89、43.95,P<0.05)。临床研究:D_(患者)组kVp情况为80 kVp,22例;100 kVp,13例。D_(患者)组图像信噪比(SNR)和CNR均高于A患者组(t=12.48、12.32,P<0.05)。两位观察者对图像质量的评分一致性较好(kappa=0.75,P<0.05)。两组图像的评分中位数均为(4,4)分(P>0.05)。结论在胸部CT增强成像中应用自动预置技术结合ODM_(full)技术,能够在满足图像质量和诊断需求的前提下,实现个体化低剂量扫描。

Objective To investigate the effect of the combination of Auto-prescription and ODM_(full) on image quality and radiation dose of chest enhanced CT inorder to explore the feasibility of individualized low radiation dose chest enhanced CT.Methods The phantoms PH-75 in two sizes were scanned with four scanning modes:group A,120 kVp+Smart-mA;group B,120 kVp+Smart-mA+ODM_(full);group C,Auto-prescription+Smart-mA;group D,Auto-prescription+Smart-mA+ODM_(full).The images of each group were reconstructed with 40%-80%ASIR-V(interval 20%),recorded as A_(1)-3-D1-3.Image quality and radiation dose were evaluated in order to obtain optimal scanning modes.Totally 35 cases(from the First Hospital of Dalian Medical University during November 2021 to July 2022)of chest enhancement CT were collected prospectively in the clinical study using the parameters of D2 group recorded as Dpatients.Patients in this group received chest enhancement CT scanning for the second time within three months.The CT parameters in first enhanced scanning recorded as Apatient were as same as those in group A_(1),and the parameters in second scanning recorded as Dpatient were as same as those in group D2.The SNRs,CNRs,subjective grading and imaging findings of the lesion in two groups were compared.Results In phantom study,the radiation dose of each group was statistically significant,and that in D group was the lowest.For two sizes of phantoms,A_(1) was uesd as the control group in pairwise comparison.The SDs of B_(1),C_(1),and D_(2) images had no statistical difference with that of A_(1)(P>0.05),and SD of D1was higher than that of A_(1),and SDs of other groups were lower than that of A_(1)(F=10.77,122.50,P<0.05).CNR of B1 had no statistical difference with that of A_(1),and the CNRs of other groups were higher(F=136.20,30.21,P<0.05).Subjective scores of A_(2),C_(2),D_(2) had no statistical difference with that of A_(1) and those of other groups were lower than that of A_(1)(H=52.89,43.95,P<0.05).In clinical study,80 kVp was uesd for 22 cases and 100 kVp was used for 13 cases in Dpatients group.SNRs and CNRs in the Dpatients group were all higher than those in the Apatients group(P>0.05).The consistency of image quality scores for two observers was good(kappa=0.754,P<0.05).The median scores of the two groups were(4,4).Conclusion Auto-prescription combined with ODM_(full) in chest enhanced CT imaging can achieve individualized low radiation dose with meeting the requirements of image quality and clinical diagnosis.