General X-Ray Machine Operator (GXMO) Practice Exam

A grid is typically utilized in diagnostic imaging when the body part being examined measures more than 10-12 cm. The primary purpose of a grid is to reduce the amount of scattered radiation that reaches the image receptor. Scattering occurs when the x-ray photons interact with the patient’s tissues, leading to a loss of image quality due to the fogging effect on the radiographic image.

When body parts are larger and thicker, such as those measuring over 10-12 cm, the likelihood of scatter is significantly increased. The grid helps in enhancing the contrast of the x-ray image by allowing only the primary radiation, which contains the useful diagnostic information, to reach the receptor while absorbing some of the scattered rays that could degrade the image quality.

Using a grid in smaller body parts, typically those measuring less than 10-12 cm, is generally unnecessary. The amount of scatter radiation in these cases tends to be lower, which means that a grid would not significantly improve the quality of the image and could potentially require a higher dose of radiation to compensate for the grid’s absorption of some primary rays.