What is the primary reason more radiation is needed when using a grid?

When using a grid in radiographic imaging, the primary reason more radiation is needed is because grids are designed to absorb scattered radiation while allowing the primary beam to pass through. This selective filtration helps improve image quality by reducing the amount of scatter that reaches the detector, which can obscure the details of the image.

However, since grids absorb some of the primary radiation as well, additional exposure is required to ensure that the correct amount of primary radiation reaches the image receptor. This is why technicians must increase the amount of radiation used when employing a grid to maintain image density and clarity.

While options related to grids absorbing radiation or enhancing film clarity are related concepts, they do not specifically address the need for increased radiation exposure to counteract the absorption characteristics of the grid.