Development of a Gd2O2S:Tb Phosphor Screen with an Anti-reflective Layer Fabricated Using Poly Chloro-para-xylylene to Improve Optical Properties in Radiography

In this study, we developed a Gd2O2S:Tb screen with a parylene-C-based antireflective (AR) layer and evaluated its optical and X-ray response properties; in particular, we focused on developing an AR coating layer to improve transmission efficiency. The phosphor screen with the parylene-Cbased AR layer can be fabricated via screen printing and chemical vapor deposition. In particular, experimental results obtained using the AR layer showed improvements of 1.47% in luminescence intensity, as well as a lower full width at half maximum of 9.40, compared to the case without using the AR layer. We observed that the roughness of the AR layer was higher than that of the phosphor screen; the image resolution improved owing to the narrow distribution of the secondary photons resulting from forward scattering attributable mainly to Mie scattering. These results indicate that parylene-C is suitable for developing AR coating materials to improve exposure efficiency while maintaining resolution in radiography systems. Therefore, we believe that the number of photons would be further increased if the AR layer were utilized in commercial products.