The Ludlum Model L-644 Grid Alignment Test Kit is designed to confirm that the proper centering, and height
uniformity of a standard or focused grid is correctly aligned with the central axis of the x-ray beam.
The test procedure is simple and requires that the holed test plate is centered to the
x-ray table and positioned such that the length of the tool is perpendicular to the direction of the grid lines. One
exposure is then made centered over each hole in the test plate. After processing, the film (image) is examined for
potential changes in optical density. A properly centered and level grid should provide 5 equal densities on the test
The test kit includes one holed test plate, 9" x 3.5", with 5 test holes. There are also 2 blocking plates which are
3.5" x 2.375". The three plates are made up of 0.0625" thick lead encased in acrylic material for ease of handling.