The two-dimensional modulation transfer function (MTF) provides a method for describing resolution in panoramic x-ray systems where the process of image formation differs in the horizontal and vertical dimensions. As an example, two-dimensional MTFs for the Philips OrthOralix SD machine were calculated from point spread functions (PSF) describing the various sources of unsharpness within the system. The PSF for the focal spot was measured using a pinhole camera. The PSF for the screen-film combination was calculated from data supplied by the manufacturer. The PSF for the motion blurring that is inherent in rotational panoramic radiography was derived from standard mathematical models. The three functions were convolved together to obtain the PSF of the entire system and the two-dimensional MTF was derived from the system PSF by Fourier transformation. The two-dimensional MTF provides a tool which should be useful in the future for the evaluation of existing systems, for the design of improved equipment, and for the implementation of image processing algorithms.
- Point spread function
- Resolution, Modulation transfer function
- Rotational panoramic radiography
ASJC Scopus subject areas
- Dentistry (miscellaneous)
- Radiology Nuclear Medicine and imaging