When should a grid be used for taking an x-ray?

A grid should be used for taking an x-ray when imaging body parts that are 10 cm or more in thickness. The primary purpose of a grid is to reduce the amount of scatter radiation that reaches the image receptor. Scatter radiation can cause fogging on the x-ray film, leading to a reduction in image clarity and detail, which is especially problematic when working with thicker body parts.

In the case of thicker anatomy, there is a higher likelihood of scatter due to the increased amount of tissue the x-ray beam penetrates. By using a grid, the radiographer can improve the overall image quality by allowing only the primary x-ray beam to pass through, while absorbing and removing much of the scattered radiation. This results in a sharper, more diagnostically useful image, which is crucial for accurate assessments in radiology.

Choosing not to use a grid for thinner body parts (less than 10 cm) is typically sufficient, as the amount of scatter is minimal, and the benefits of using a grid may not outweigh the potential drawbacks, such as increased patient dose and the need for a higher exposure technique.