Digital Tomographic Filtering of Radiographs

Conventional radiographs do not provide information about the depths of details and structures because they are two-dimensional projections of three-dimensional bodies. Taking advantage of the finite size of the X-ray source and the divergent nature of the X-ray beam, a radiograph can be processed by two-dimensional digital filtering techniques, so that the image of a particular layer is improved, while the others are degraded. This technique is referred to as a tomographic filtration process (TFP). This paper develops the mathematical and physical foundations of the method. Based on a model of the radiologic process, which is described in the paper, the equations of image formation in standard tomography, conventional radiography, and tomographic filtering are derived and compared.

[1]  Kunio Doi,et al.  The Application of Optical Transfer Function in Radiography , 1964 .

[2]  H.J. Trussell,et al.  Processing of X-ray images , 1981, Proceedings of the IEEE.

[3]  Robert D. Moseley,et al.  Diagnostic radiologic instrumentation : modulation transfer function , 1965 .

[4]  G U Rao,et al.  An intercomparison of the modulation transfer functions of square and circular focal spots. , 1974, Medical physics.

[5]  E Takenaka,et al.  Modulation transfer function of the intensity distribution of the roentgen focal spot. , 1968, Acta radiologica: therapy, physics, biology.

[6]  K DOI,et al.  OPTICAL TRANSFER FUNCTIONS OF THE FOCAL SPOT OF X-RAY TUBES. , 1965, The American journal of roentgenology, radium therapy, and nuclear medicine.

[7]  S C Orphanoudakis,et al.  Mathematical model of conventional tomography. , 1976, Medical physics.

[8]  B. Hunt.  The inverse problem of radiography , 1970 .

[9]  Morgan Rh,et al.  The frequency response function. A valuable means of expressing the informational recording capability of diagnostic x-ray systems. , 1962 .

[10]  B. G. Ziedses Des Plantes,et al.  Body‐section Radiography: History, Image Information, Various Techniques and Results , 1971 .

[11]  R. F. Wagner,et al.  Toward a unified view of radiological imaging systems. Part II: Noisy images , 1974 .

[12]  Ernest L. Hall,et al.  A Survey of Preprocessing and Feature Extraction Techniques for Radiographic Images , 1971, IEEE Transactions on Computers.

[13]  R. F. Wagner,et al.  Toward a unified view of radiological imaging systems. Part II: Noisy images. , 1977, Medical physics.

[14]  K Rossmann,et al.  Modulation transfer function associated with geometrical unsharpness in medical radiography. , 1967, Physics in medicine and biology.

[15]  C E Metz,et al.  Linearizing mechanisms in conventional tomographic imaging. , 1978, Medical physics.

[16]  M Trefler,et al.  The diagnostic quality of optically processed radiographs. , 1976, Radiology.

[17]  D. Falconer.  Image Enhancement and Film-grain Noise , 1970 .

[18]  John W. Strohbehn,et al.  Image Enhancement of Conventional Transverse-Axial Tomograms , 1979, IEEE Transactions on Biomedical Engineering.

[19]  Anastasios N. Venetsanopoulos,et al.  Evaluation of Digital Tomographic Filters , 1985, IEEE Transactions on Medical Imaging.

[20]  P. Edholm,et al.  The Tomogram: Its Formation and Content , 1961, Acta radiologica. Supplementum.

[21]  R. F. Wagner,et al.  Toward a unified view of radiological imaging systems. Part I: Noiseless images. , 1974, Medical physics.

[22]  Michael W. Vannier,et al.  Digital Processing Of Conventional Tomograms , 1981, Other Conferences.

[23]  Bobby R. Hunt,et al.  Scan and Display Considerations in Processing Images by Digital Computer , 1975, IEEE Transactions on Computers.

[24]  W R Hendee,et al.  Effects of x-ray tube current and voltage on effective focalspot size. , 1974, Medical physics.

[25]  Albert Rose,et al.  A Unified Approach to the Performance of Photographic Film, Television Pickup Tubes, and the Human Eye * --> , 1946 .

[26]  Jose M. Costa.  Tomographic Filters For Digital Radiography , 1981, Other Conferences.

[27]  H C Andrews,et al.  Monochrome digital image enhancement. , 1976, Applied optics.

[28]  S K Hilal,et al.  Optical filtering to compensate for degradation of radiographic images produced by extended sources. , 1968, Applied optics.

[29]  Kunio Doi,et al.  Role of Optical Transfer Function for Optimum Magnification in Enlargement Radiography , 1970 .