Grids are used in a test phantom to check the quality of x-ray images. Such a grid may consist for example, of gold structures on a silicon surface and a grid period length of 2 micrometer with space wide in between of 1 micrometer.
Filter grids are also used in x-ray imaging to reduce noise contributed by scatter.

The grid efficiency or grid selectivity describes the efficiency in % of the primary beam transmission / % of transmitted scatter. The absorption of the primary beam is around 20 - 40%.

The grid factor (also called bucky factor) defines the requirement to increase the exposure factors to maintain density with the use of a grid.

(gf) The grid frequency is the number of lead strips per inch or centimeter. An increased grid frequency involves thinner stripes. The most used grid frequency is 85 -103 lines per inch.

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