GRID ALIGNMENT QUALITY CONTROL TEST
The grid alignment test reveals the alignment or misalignment of the radiographic
grid to the center of the image receptor and to the x-ray tube central ray. It is a simple
test, but just as important as any other because a misalignment of the grid can cause
uneven densities on the final radiograph.
a. Grid test tool.
b. Loaded 8- x 10-inch film holder.
d. Data form.
a. Set the SID.
Adjust the tube perpendicularly (crosswise) to the table.
Use the proper SID for that table's grid (usually 40, but not always).
b. Center the x-ray tube, first longitudinally, then transversely (crosswise) and
lock in place. If the tube has a transverse lock mechanism, use it.
c. Place an 8- x 10-inch film holder in the tray with the long axis of the film
perpendicular to the long axis of the table. Be sure that the cassette tray is completely
Lock the bucky tray.
e. Position the grid alignment test tool on the tabletop with the tool in a
perpendicular position to the long dimension of the x-ray tube. Then center the zero
position of the test tool to the optical cross hairs of the beam restriction system. Ensure
that the orientation arrow is toward the front of the x-ray table (see figure 10-1).