婴幼儿胸部DR摄影源像距与辐射剂量和图像质量的相关性研究

目的 探讨婴幼儿胸部数字X射线摄影(DR)的源像距(SID)与图像质量及辐射剂量的相关性.方法 先进行仿真胸部体模(成都剂量体模)实验性曝光,采用同一管电压(65 kVp)和不同SID进行曝光组合,记录每次曝光的毫安秒(mAs)、单位面积剂量:在实验的基础上进行婴幼儿胸部DR,收集2008年5月～2010年5月初次人院的50例婴幼儿行胸部DR(其中男性28例,女性22例;年龄5个月～2岁,平均年龄10个月),住院期间复查1次作为对照,初检组均使用110cmSID,复检组均使用90cmSID进行DR胸部摄影.由3名资深影像学专家对获取的100幅图像质最进行评判,评判结果运用统计学软件SPSS 13.0进行分析,使用接受者操作特征曲线(ROC)分析和t检验.结果 100例初检及复查婴幼儿的图像质量均符合诊断要求(P>0.05);而不同的SID曝光的面积剂量差异有统计学意义(P<0.05).结论 婴幼儿胸部DR的不同SID,其辐射剂量差异具有统计学意义,且图像质量均能满足诊断要求,90cmSID在婴幼儿胸部DR中值得提倡.

Correlative study of focal spot to image receptor distance on radiation dose and image quality in chest digital radiography in infants

Objective To investigate effect of the focal spot to image receptor distance（SID） on image quality and radiation dose in infants chest digital radiography（DR）. Methods The Chengdu dosimetric phantoms were used to expose with 65 kVp and different SID. The result was adopted in infant DR after the mAs and radiation dose of each exposure were recorded and analyzed. From May 2008 to May 2010, 50 infants were enrolled, male 28, female 22, aged 5-month to 2-year-old, mean age 10-month, which examined before admission and discharged by same digital X-ray machine with SID = 110 cm and SID = 90 cm separately. All cases were used auto exposure control system. The 2 groups of data obtained to compare radiation dose, and then 3 experienced image experts assessed the quality of 100 images. The SPSS 13.0 statistical software was used to analyze receiver operating characteristic curve （ROC） and t test. Results All the images meet the demands for diagnosis（P 〉 0.05）, and which 2 methods acquired were not very different from the clinical significance. There was significant difference in radiation dose using different SID. Conclusion It is demonstrated that the radiation dose has significant difference dose using different SID in infant chest DR, but all images meet the demands for diagnostic. SID = 90 cm was advocated for infants chest DR.