Evaluation of high grid strip densities based on the moiré artifact analysis for quality assurance: Simulation and experiment

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Accelerators, spectrometers, detectors and associated equipment, 2017-09, Vol.866, p.58-64
• Main Authors: Je, U.K., Park, C.K., Lim, H.W., Cho, H.S., Lee, D.Y., Lee, H.W., Kim, K.S., Park, S.Y., Kim, G.A., Kang, S.Y., Park, J.E., Kim, W.S., Jeon, D.H., Woo, T.H.
• Format: Article
• Language: English
• Subjects: Grid strip density; Moiré artifact; Nyquist sampling rate; Quality assurance
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/j.nima.2017.06.001

We have recently developed precise x-ray grids having strip densities in the range of 100 – 250 lines/inch by adopting the precision sawing process and carbon interspace material for the demands of specific x-ray imaging techniques. However, quality assurance in the grid manufacturing has not yet satisfactorily conducted because grid strips of a high strip density are often invisible through an x-ray nondestructive testing with a flat-panel detector of an ordinary pixel resolution (>100 μm). In this work, we propose a useful method to evaluate actual grid strip densities over the Nyquist sampling rate based on the moiré artifact analysis. We performed a systematic simulation and experiment with several sample grids and a detector having a 143-μm pixel resolution to verify the proposed quality assurance method. According to our results, the relative differences between the nominal and the evaluated grid strip densities were within 0.2% and 1.8% in the simulation and experiment, respectively, which demonstrates that the proposed method is viable with an ordinary detector having a moderate pixel resolution for quality assurance in grid manufacturing. •The precise carbon-interspaced antiscatter grids have been studied.•It is proposed for a useful method to evaluate actual grid strip densities over the Nyquist sampling rate based on the moiré artifact analysis.•The simulation and experimental results demonstrate that the proposed method is viable with an ordinary detector having a moderate pixel resolution (>100 μm) for quality assurance in grid manufacturing.