帧率与电子放大射野对数字减影血管造影受检者剂量的影响

Effect of FR and EM on DSA dose of subjects

目的:研究帧率(FR)和电子放大射野(EM)对数字减影血管造影(DSA)设备所致受检者X射线入射体表空气比释动能率(ESKAR)的影响。方法:选取4种型号的DSA设备(定义为1~4号机),在临床常用的FR和EM组合条件DSA模式下曝光测量ESKAR。随机选取3号机,分别测量DSA模式和透视模式中3 f/s FR与不同EM组合条件下的ESKAR。分别将EM与标化ESKAR以及FR与标化ESKAR进行拟合,并比较标化前后不同EM条件下ESKAR的变异系数的差异,比较DSA模式与透视模式ESKAR的统计学差异。结果:标化ESKAR与FR及EM均呈不同函数关系,包括线性函数关系、对数函数关系及多项式函数关系,其中标化ESKAR与FR多呈线性函数关系,与EM多呈多项式函数关系。在相同EM下3号机DSA模式产生的ESKAR为(2395.8±14.8)μGy/s,EM为48 cm,远大于透视模式的(16.7±0.7)μGy/s,EM为48 cm,差异有统计学意义(t=359.3,P<0.001)。但在对ESKAR进行毫安秒标化后则出现既有DSA模式大于透视模式也有透视模式大于DSA模式的情况。结论:DSA模式下标化ESKAR与FR和EM成函数关系,其总体趋势为EM越大则标化ESKAR越低,FR越大标化ESKAR越高。介入医师应谨慎使用FR和EM功能,熟悉各机型FR及EM与剂量的关系,以降低受检者剂量。

Objective:To study the effect of frame rate(FR)and electronic magnification size(EM)on the entrance surface air kerma rate(ESAKR)of X-ray of subjects caused by digital subtraction angiography(DSA)equipment.Methods:4 types of DSA equipment which were defined from No.1 to No.4.ESAKR were measured under DSA mode with common composition condition of FR and EM of clinical practice.The No.3 DSA equipment was randomly selected,and the 3 f/s FR of DSA model and fluoroscopy model and the ESKAR under different EM composition condition were measured,respectively.The EM and FR were used to fitting with standardized ESKAR,respectively.And the difference of the coefficient of variation(CV)of ESKAR under different EM condition between pre and post standardization was compared,and the statistic difference between DSA model and fluoroscopy model was further compared.Results:There were different function relationships between standardized ESKAR and FR,and between standardized ESKAR and EM,which included linear function relationship,logarithmic function relationship and polynomial function relationship.Among of them,the standardized ESKAR appeared linear function relationship with FR in the most of situations,and it appeared polynomial function relationship with EM in the most of situation.The ESAKR produced by the model of No.3 DSA equipment was(2395.8±14.8)uGy/s under the same EM that was 48 cm,which was greatly larger than that by fluoroscopy model(16.7±0.7 uGy/s,EM=48cm),and the difference of that between them was statistically significant(t=359.3,P<0.001).However,the DSA mode did not always deliver larger ESAKR than that of fluoroscopy model after the ESAKR were standardized by mAs.Conclusion:The standardized ESKAR appeared function relationship with FR and EM under DSA model,respectively.The total trend is the standardized ESKAR decreases with the increasing of EM and that increases with the increasing of FR.The radiologists who conduct intervention should cautiously use FR and EM,and should be familiar with the relationships between the FR and EM of each type of equipment and the dose,so as to reduce the dose of subjects.