Patent Number: 061817732
Section: abstract

A radiation anti-scatter device comprising a grid and a grid driver connected to the grid for unidirectionaly moving the grid with a variable grid velocity along a path between a starting and an end position, and a method of providing such grid motion. The variable grid velocity may have a velocity profile V.sub.1 =k.sub.1 t for a first period and then V.sub.2 =k.sub.2 t.sup.-m for a second period, where V.sub.1 and V.sub.2 are velocity, k.sub.1 and k.sub.2 are constants, t is time, and m is an exponent having a value greater than 0. The anti-scatter device may be a component of a direct radiographic diagnostic imaging system which includes an image-producing element having an array of radiation detectors aligned in rows, and where the anti-scatter device is a grid having vanes oriented at an angle to the detector rows. Radiation emission may be synchronized with the grid motion to optimize a radiograph for a particular grid, radiation source, or examination procedure. The apparatus implements a method for reducing Moire patterns in radiographic detectors having an array of sensors by unidirectionaly moving the grid in a single stroke during the radiation exposure with an asymptotically decreasing speed profile such that grid motion is maintained for a plurality of different radiation exposure times.