X-ray grids are often thought of something that you purchase, install, and never think about again. They are sitting in your bucky tray invisible to you, that is, until they are not. Oftentimes, when upgrading to digital x-ray from film, CR, or even an older DR detector, users see grid artifacts on their images. Why does this happen?
Damage, of course, is the first reason you may need to replace your old grid. Grids can break or bend. This usually isn’t an issue inside a table or wall stand, but grids user in portable applications can easily become damaged. Most often, this shows up as one or more clear lines on the image where the lead and interspacer have split. Oftentimes, these lines will not run the full length of the image. This can help determine that the artifacts are indeed from your grid and not your digital x-ray detector.
The second reason for replacing an old grid is due to the x-ray system being upgraded from film or CR to DR. When using a DR system, you will need to make sure you’re using a grid that works properly with your new detector.
If you were using a reciprocating bucky previously, you will now need to turn it off. The electromagnetic interference from the motors or magnets in a reciprocating bucky can cause unpredictable effects on a digital x-ray panel.
If your system is intended to utilize a static grid, you will need one of two grids: a 103 lpi grid that can be handled by your DR system’s grid suppression software; or a high line grid that is fine enough to be invisible to the detector. The high line grid will provide the highest possible image quality, but is also significantly more expensive. Only a very few companies in the world can manufacture such grids. Many private clinics choose to go with the 103 lpi grid instead.
In some instances, the system may already be using a 103 lpi grid that needs to be replaced. The standard requirements for the accuracy of the line county in a grid are +/- 10%. Older grids and grids from less expensive manufacturers tend to be towards the extremes of that variation, and may not be close enough to a true 103 lpi grid to work with your system’s grid suppression software. When this occurs, the grid needs to be replaced by a newer grid from a supplier with tighter tolerances.