婴幼儿胸部DR摄影距离对体表入射剂量与图像质量的影响

目的 探讨胸部数字化X线摄影源像距(SID)对婴幼儿体表入射剂量(ESD)与图像质量的影响.方法 先进行仿真胸部体模实验性曝光,采用同一管电压(60 kVp)和不同SID(150 ～80 cm,10 cm为一组,共8组)进行曝光组合,记录每次曝光的毫安秒、ESD.选取试验中ESD相对剂量适中和较低的两组(110和90 ...

Effects of source to image receptor distance on image quality and entrance surface dose of chest digital radiography for infants

Objective To investigate the effects of source to image receptor distance (SID) on the image quality and entrance surface dose (ESD) in the chest digital radiography (DR) for infants.Methods Anthropomorphic chest phantoms were exposed to 60 kVp and different values of SID ( 150 -80 cm with the interval of 10 cm,totally 8 groups) so as to record the values of mAs and ESD.The SID values of 110 cm and 90 cm with the moderate and low ESD values were selected for clinical test.Forty-two hospitalized infants,aged 12 months (8 months to 2 years) underwent chest DR with the SID of 110 cm before admission and 90 cm before discharge respectively.The values of ESD were recorded and compared.Three experienced experts assessed the quality of 84 pieces of images.Results The values of mAs and ESD decreased gradually along with the decrease of the SID from 150 cm to 80 cm.All the 84 images from the 42 infants met the demands for diagnosis.There was no significant difference in the score of image quality of the group with the SID of 110 cm (4.4±0.3) and 90 cm(4.2±0.4) (t=0.453,P＞0.05).The value of ESD of the group with the SID of 90 cm was significantly lower than that of the group of SID of 110 cm by 0.003 4 mGy ( t =12.001,P ＜ 0.05 ).Conclusions The image quality of chest DR could meet the demands for diagnosis in spite of the value of SID,however,the SID value in chest DR significantly might influence the ESD.The SID value of 90 cm shoud be recommended in chest DR for infants.