Research On The Data Acquisition And Imaging Performance Test Of Flat Panel Detector

DR technology has become the main direction of the radiography testing. Flat panel detector(FPD) is the core instrument of DR system, whose manufacturing process and imaging performance directly decides the quality of the output image. DR imaging technology in the field of non-destructive testing is hindered to some extent for the lack of flat panel detector system acceptance criteria, this paper focuses on the detector performance parameters testing based on the XRD0822 amorphous silicon flat panel detector and designs DR acquisition software through VC++6.0 platform.Firstly, the relative curve between warm- up time and average gray of dark- field image is established and found that dark- field image data obtained from FPD which preheat in 30 minutes will become more stable and less volatile. Based on research of the dark field image, the corrected gain field image is obtained with using linear correction formula. Then, according to the differences in pixels of response sensitivity on X-ray, the bad points were accurately classified and a total of dead pixels location map is obtained. Several DR images of aluminum honeycomb panels is compared quantitatively, the result shows that DR image quality has improved significantly after correction on dark field, gain and bad pixels. Further, a multi-exponential decay model for residual signals is established in terms of the relationship between the value and the exist times of residual signals and quality improvement on DR image of blade is achieved with using residual signals correction algorithm.Secondly, the research on the parameters of FPD, such as: the basic spatial resolution, contrast sensitivity, MTF, NPS, DQE and dynamic range are launched by a series of experiments. The spatial resolution test shows that the basic spatial resolution in row direction and in column direction are 2.5 lp/mm and 2lp/mm respectively; Contrast sensitivity test results show that the optimal contrast sensitivity of FPD can reach 2% for iron or steel with thickness below 38.1mm; MTF measurements indicate that the limit spatial resolution of DR ima ging will reach 2.5 lp/mm when the modulation reach 0.1; Studies on NPS find that detector noise is basically same in both directions, and the quantum noise is the main source of total imaging noise, which is presents Poisson distribution. The electronic noise obeys the law of Gaussian distribution with white noise Character. The measurement on DQE curve shows that SNR will decline with increasing of spatial frequency in FPD, value of DQ E is 0.7 in 0 lp/mm and reach maximum in 1 lp/mm. In addition, response property of FPD for X-ray energy and intensity is studied, which prove that response of FPD for X-ray intensity is linear and X-ray energy response curve of FPD is non-linear curve.The correction of detector is of great significance to the improvement of the quality of the original image. Analyzing the relationship of various performance parameters can provide guidance to establish performance acceptance standard, and serve the option of exposure parameters.