16层CT肺部筛查低剂量技术研究

Low-dose Technique of Lung Screening with a 16-slice CT Scanner

目的：探讨16层螺旋CT肺部低剂量扫描中剂量与体格的关系。材料和方法：收集150例健康体检低剂量胸部CT，男性89例，女性61例。身高1．52～1．82m，平均1．66m，体重45～86kg，平均63．13kg。采用TOSHIBA Aquilion 16层CT 自肺尖至肺底扫描。扫描参数：准直1mm，螺距15（0．938），FOV280～330mm，120kV，0．5s／Rot。重建层厚肺窗7mm，纵隔窗10mm。设计给予4种剂量进行扫描并进行比较。结果：全部病例在20mAs及更小剂量条件下获得可以用于筛检的图像，不必使用高条件。多数病例在10mAs条件下可以获得适用于筛检的图像（96例，64％），少数可以用更小剂量（16例，10％），其余需要稍高条件（38例，26％）。10mAs剂量取得良好图像者的身高体重比95％可信区间为1．00～1．03，需要20mAs的为1．13～1．22，仅需5mAs的为0．83～0．88。结论：16层CT肺部筛查最小剂量随体格不同而有变化，10mAs即可适用于多数人群，20mAs几乎可以覆盖全部人群。

Purpose： To explore the low dose related with the body build in lung screening using a 16- slice CT scanner. Materials and Methods： Lung screening was performed in 150 healthy volunteers（male 89, female 61, height 152 ～182cm, mean 166cm; weight 45 ～ 86kg, mean 63.1kg ） during Mar 2004 to Apt 2005 with a TOSHIBA Aquilion 16- slice CT scanner. The imaging parameters were 1.0 mm collimation, p = 0.938, 120kV, 0.5s/ Rot, and FOV 280～330mm. Slice thickness of 7.0 mm with lung window and 10mm with mediastinal window setting were reconstructed, respectively. Four dosages were used and compared in screening. Results： All patients had obtained the good quality images using a dose of no more than 20 mAs. Most of them only need a dosage of 10mAs（96 patients, 64%）, and the others need 5mAs（16 patients, 10%） or 20mAs（38 patients,26%）. The 95% confidence interval of the ratio of height and weight was 1.00～ 1.03 for 10mAs, 0.83 ～0.38 for 5mAs, and 1.13 ～ 1.22 for 20mAs. Conclusion： The lowest screening dose could change with the body build. The dosage of 10mAs might be applied in most screening, and that of 20mAs almost in all of patients.