Analysis of stationary grid artifact on computed radiographic image

Objective: To analyze sampling frequency and grid density frequency on the computed radiography (CR) system and to develop an effective method to suppress or eliminate grid artifacts. Methods: To test grids with different grid-density in combination with IP boards of different specifications. Radiographic images with various qualities were obtained by simulating two kinds of signaling frequencies (namely two kind of grids with different grid densities), and utilizing three kinds of sampling frequencies (6, 8, 10 pixels/mm). A variety of different simulation images were obtained. Results: By comparing simulation images with actual images, it was discovered that correct signaling frequency could be achieved if the sampling frequency were equal to twice the signaling frequency. The obtained image was clear and free of grid artifact. A grid density of < 4 LP/mm was most suitable for IP boards of 14 in x 14 in, 10 in x 12 in, in size. Conclusion: Appropriate combination of the CR System and IP boards with matching sampling frequency and grid-density frequency can effectively eliminate or reduce grid artifacts. (authors)