DSA测量技术误差与控制

目的探讨DSA测量技术误差的产生与控制。方法在GE公司生产的Advantx LCV Plus DSA机上测得数据。将显示屏分为中央区、中间区及边远区3个区带，对不同大小定标在不同检查床高度及不同点光源与增强器高度（SID）条件下，测量标的（人民币5角硬币）的放大、缩小情况。结果随着标的外移，由中央区到边远区标的逐渐放大，且纵向放大比横向放大显著。不同的定标对比，硬币（直径20．4mm）和钢球（直径7．7mm）测量相同标的结果相差较小，而导管（4F）定标有显著的低估实物倾向。同区带同轴向测量，测量误差控制在1．0％～-2．5％之间。结论将显示屏划分为中央区、中间区及边远区将有助于介入医师对测量误差的控制。以定标物的横向做定标来测量标的较为准确，同区带同轴向测量误差控制较好。

Assessment of the error of measurement technique on DSA

Objective To explore the creation and control of measurement technique error on digital subtraction angiography (DSA). Methods The data was obtained from Advantx LCV Plus DSA system made by GE Corporation. We divided the screen into three areas, per area account for 1/3, ie, central area, middle area and outlying area. The enlargement rate or reduction rate of the target object was respectively calculated according to the different calibration, different height of the bed and different X-ray source to image distance (SID). Results The target object was enlarged gradually from the central area to the outlying area, and the lengthwise enlargement rate was more obvious than transverse. The different of target object measured by coin (diameter was 20.4 mm) with steel ball (diameter was 7.7 mm) was not significance, but the target object was underestimated significantly used the calibration by 4F catheter. When the target object was measured by the calibration in same area and same axis, the error of measurement technique was controlled rang from 1.0% to-2.5%. Conclusion This systematic investigation suggest that the screen was divided into the central area, middle area and outlying area will be beneficial to control DSA measurement error for the interventional physician. The target object was close to real size when it measured by transverse of the calibration, and the error was better controlled when the calibration was in the same area and same axis as the target object.