Investigation of basic imaging properties in digital radiography. 12. Effect of matrix configuration on spatial resolution.

We investigated the effects of three matrix configurations (a conventional 512 X 512 matrix, a double-sampling matrix, and a high-resolution 1024 X 1024 matrix) on the resolution properties of an image intensifier (II)-TV digital radiographic imaging system. Expressions for the optical transfer function were derived theoretically for each of the three matrix configurations, and the corresponding digital modulation transfer functions (MTF's) were calculated using the measured MTF's of the presampling analog components and the parameters of the digital system. In addition, digital images of a star pattern phantom and a hand phantom were obtained with the II-TV system for each matrix type. From our results, we conclude that, in order to increase the resolution of an II-TV digital imaging system, it is necessary not only to increase the matrix size, but also to improve the resolution capabilities of analog components such as the II and/or TV camera. In addition, if the system cannot be upgraded to a 1024 X 1024 matrix configuration, a double-sampling technique with an 512 X 512 matrix may be employed.