LINE PAIR

These x-ray test patterns are designed for quick quantitative assessments of the limiting spatial resolution in an X-Ray system. The line pair patterns consist of a thin lead foil layer sandwiched between plastic plates. In the foil, linear slits are cut with a range of widths, these alternate with linear bars of the foil of equal width. One slit and one bar is referred to as a line pair, and the width of each group of lines is specified in terms of the number of line pairs per mm (LP/mm). The observer counts the number of groups in which he can resolve the slits from the bars and as such can determine the resolving capability of the x-ray system in terms of LP/mm. A wide range of pattern designs is available with varying ranges of LP/mm and foil thicknesses... Foil thickness affects the effective kVp range the phantom is used for. 0.01mm - 0.03mm for mammography (25kV-32kV), 0.05mm - 0.1mm for general radiographic/fluoroscopic (50-150kVp).