Contrast improvement factor

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The contrast improvement factor of an anti-scatter grid is the ratio of contrast obtained with the use of the grid to the contrast without the use of the grid.

Hence, the contrast improvement factor reflects the increased image quality obtained from grid use.

Most grids will have a contrast improvement factor between 1.5 and 3.5.

The contrast improvement factor is primarily determined by the lead content and the grid ratio.

However, the following factors that affect the amount of scattered radiation produced will also affect the grid's ability to improve image contrast:

  • kVp (decreases with increased energy)
  • patient thickness (decreases with thicker body parts)
  • area irradiated (decreases with larger field size)