Abstract: For DR detection technology, the size of the X-ray source focus, geometric magnification, detector pixel size, and image calibration reference size are key factors affecting the measurement accuracy of DR detection technology. Therefore, through DR experiments based on a single variable method, the influence law of the above four factors on the measurement error of size quantification was qualitatively analyzed. On this basis, a high-precision size quantitative method based on defect size selection of benchmark blocks was proposed and verified by experiments on actual workpieces. The results showed that the size of the X-ray source focus and detector pixel size are proportional to the quantitative measurement error, while the geometric magnification shows a trend of decreasing first and then tending to be regionally stable with the measurement error. The actual physical size of a single pixel is directly related to the reference size. Under the premise that DR image quality meets detection standard requirements, the closer the reference size is to the actual defect size, the lower the quantitative measurement error will be. By selecting appropriate benchmark blocks, measurement errors can be effectively controlled within ±0.05 mm.

Key words: digital radiography, dimension quantitative measurement, the focus size of the X-ray source, the geometric magnification, detector pixel size, the measurement error