What artifact can result from a grid used in CR that has a frequency similar to the CR processor's scan frequency?

What artifact can result from a grid used in CR that has a frequency similar to the CR processor's scan frequency?

• A. Quantum mottle
• B. Aliasing/Moiré effect
• C. Beam hardening
• D. Image noise

Answer: (B)

The phenomenon that can occur when a grid used in computed radiography (CR) has a frequency similar to the scanning frequency of the CR processor is known as the aliasing or Moiré effect. This effect arises when two repetitive patterns overlap, which in this case is the grid lines and the scanning lines of the CR processor. When the frequencies are similar, the result can be a visual artifact where wavy or band-like patterns appear in the image.

This is primarily due to the interference between these two patterns, leading to image distortion that is not representative of the actual anatomy being imaged. The Moiré effect can significantly reduce the diagnostic quality of the radiographic image, making it important for radiologic technologists to choose grid patterns that are appropriately matched with the digital systems they are using to avoid this issue.

In contrast, quantum mottle refers to graininess in images due to insufficient radiation exposure, beam hardening is a phenomenon that affects the quality of the image due to the varying energy of x-rays, and image noise can derive from various sources such as electronic interference or low signal-to-noise ratios. None of these effects result from the interaction of grid and scan frequencies in the way that the Moiré effect does.