朱蕾,刘云福,康天良,张永县,许庆刚,王永哲,牛延涛.低管电压扫描技术在CT泪囊造影成像中的应用研究[J].中华放射医学与防护杂志,2021,41(3):212-216
低管电压扫描技术在CT泪囊造影成像中的应用研究
Study of the application of low tube potemtial scanning in dacryocystography CT
投稿时间:2020-08-13  
DOI:10.3760/cma.j.issn.0254-5098.2021.03.010
中文关键词:  CT泪囊造影  辐射剂量  低管电压
英文关键词:Dacryocystography CT  Radiation dose  Low tube potential
基金项目:
作者单位E-mail
朱蕾 首都医科大学附属北京同仁医院放射科 100730  
刘云福 首都医科大学附属北京同仁医院放射科 100730  
康天良 首都医科大学附属北京同仁医院放射科 100730  
张永县 首都医科大学附属北京同仁医院放射科 100730  
许庆刚 首都医科大学附属北京同仁医院放射科 100730  
王永哲 首都医科大学附属北京同仁医院放射科 100730  
牛延涛 首都医科大学附属北京同仁医院放射科 100730 ytniu163@163.com 
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中文摘要:
      目的 探讨低管电压扫描方案在CT泪囊造影成像中的可行性。方法 采用拟人头颈部模体,将对比剂(碘海醇)与盐水1 ∶3混合液置于模体鼻翼一侧模拟泪囊。分别采用80、100、120和140 kV对模体进行扫描,每种管电压选择相应的mAs使设备显示的容积CT剂量指数(CTDIvol)分别为10、15、20、25、30、35和40 mGy。结合对每组图像的客观评价,以临床扫描参数120 kV/180 mAs的对比度噪声比(CNR)为基准,得出相同CNR时的最低剂量扫描参数80 kV/240 mAs。前瞻性收集2019年11月至2020年7月来北京同仁医院收治的62例泪囊CT扫描患者,按随机数表法分为常规管电压组(120 kV/180 mAs)和低管电压组(80 kV/240 mAs),每组各31例。测量两组图像的CT均值、噪声(SD)及对比噪声比(CNR)作为图像质量客观评价指标,主观评价由两位高年资主治医师采用双盲法进行5分制评价。结果 模体研究中相同管电压下,CTDIvol增加CNR也增加,两者呈正相关(r=0.985、0.965、0.971、0.972,P<0.05);相同CNR下,管电压越低,辐射剂量越低;临床扫描参数120 kV/180 mAs的CNR为27.8,而80 kV在相同CNR时对应的是240 mAs;临床研究中常规管电压组和低管电压组的CTDIvol分别为31.2和12.8 mGy,低管电压组较常规管电压组降低了约59%。两组图像泪囊区CT值、眶内脂肪区CT值与噪声差异均有统计学意义(t=-3.476、2.601、-5.704,P<0.05),两组图像的CNR差异无统计学意义(P>0.05)。两名观察者间的一致性良好(Kappa>0.75),两组图像主观评分差异无统计学意义(P>0.05)。结论 使用低管电压技术扫描可以获得满意的泪囊CT图像质量,同时有效降低辐射剂量。
英文摘要:
      Objective To investigate the feasibility of the application of low tube potential scanning in dacryocystography CT. Methods The mixture of iohexol and saline with the ration of 1:3 as the dacryocyst was set on the nose wing of the head-neck phantom. The phantom was scanned at 80, 100, 120, 140 kV with appropriate mAs to set the volume CT dose index(CTDIvol)at 10,15,20,25,30,35 or 40 mGy. All the images were objectively evaluated to find out the optimal scanning parameters of 80 kV/240 mAs with the same contrast-to-noise ratio(CNR)of conventional scanning condition of 120 kV/180 mAs. A total of 62 patients who conducted dacryocystography CT in Beijing Tongren Hospital from November 2019 to July 2020 were prospectively selected. They were randomly divided equally into conventional scanning group with 120 kV/180 mAs and low tube potential group with 80 kV/240 mAs. The CT number, noise (SD) and contrast-to-noise ratio (CNR) of the two groups were measured as the objective evaluation indicators of image quality. The subjective evaluation was performed by two senior radiologists using a double-blind method and a 5-scale system evaluation. Results For the phantom study, the CNR was positively correlated with CTDIvol under the same tube potential (r=0.985, 0.965, 0.971, 0.972, P<0.05). With the same CNR, the radiation dose decreased with lower tube potential. Under the conventional scanning parameters of 120 kV/180 mAs, the CNR was 27.8. At the same CNR, the optimal scanning parameters were 80 kV/240 mAs. For the clinical study, the CTDIvol of conventional scanning group and low tube potential group were 31.2 and 12.8 mGy respectively, 59% decreased in low tube potential group. There were statistically significant differences in CT number of dacryocyst area, CT number of orbital fat area and noise between the two groups (t=-3.476, 2.601, -5.704, P<0.05). There was no statistically significante difference in CNR between 2 groups(P>0.05). Two observers had a good consistency (Kappa >0.75). There was no statistically significante difference in subjective rating between 2 groups(P>0.05). Conclusions Low tube potential scanning could obtain satisfactory image quality in dacryocystography CT at much lower radiation dose.
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