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Influences of incorrect placement of the focused grid on an x-ray image formation

1998; SPIE; Volume: 3336; Linguagem: Inglês

10.1117/12.317070

1996-756X

Takanori Tsunoo, Nobuyuki Nakamori, Hitoshi Kanamori, Yasuo Yoshida,

Advanced X-ray Imaging Techniques

We have studied the influence of incorrect placement, such as the lateral decentering, the inclination and the x-ray source out of the focused distance, of the focused grid on the image formation in a computer simulation. We have applied Monte Carlo methods to determine the absorption and scattering of photons inside water phantoms and traced the radiation transmitted from the phantom through the focused grid. We have examined the dependence of the transmittance of primary radiation and that of the transmittance of scattered radiation on various grid parameters and radiographic conditions. The grid exposure factor and the contrast improvement factor as well as the primary radiation loss were used for comparison of the relative performance of the grid, and relationship among these factors was studied. We found that the lateral decentering and the inclined grid degraded the image remarkably. The higher the grid ratio is, the more sensitively the misplacement of the grid degrades to the image.