Grid Alignment Test Tool

Increased patient radiation dose and reduced image contrast can result from lateral decentering or tilting of a focused grid used in a Bucky apparatus. The Grid Alignment Test Tool is used to check whether a focused grid is aligned properly with the central ray and the center of the film cassette.

The 07-644 consists of a set of three plastic-covered, 0.062 inch thick lead plates: one 9.125 x 3.625 inch test plate, and two 3.56 x 2.375 inch blocker plates. The large test plate contains five 0.375 inch test holes and five 0.062 inch orientation holes.

This Grid Alignment Test Tool is easy to use. The 07-644 is centered on the x-ray table and fixed in position perpendicular to the grid lines. Five exposures are made, with the x-ray beam sequentially centered on each of five holes, and the optical densities of the hole images are compared. A properly centered and leveled grid will result in equal density changes in the hole images on either side of the central hole. Unequal density changes indicate the need for corrective action.