Final answer:
Radiographic grids are typically used in chest radiography for exposure factors using 100 kV or greater to absorb scattered radiation and improve image quality. Lower kV settings are less likely to produce significant scatter, thus may not require a grid. The use of grids is determined by patient size, body part imaged, and radiation protection principles.
Step-by-step explanation:
The general rule for using radiographic grids in chest radiography is typically for exposure factors using 100 kV or greater. This is because at lower kilovoltages, the scattering of x-rays is not as significant. As the kilovoltage (kV) increases, more scatter occurs, and a grid is necessary to help improve the quality of the radiographic image by absorbing scattered radiation.
When using an x-ray tube at lower energies, such as 50.0 kV for a chest x-ray, the penetration through the chest is sufficient for a clear image without excessive scatter that would require a grid for cleanup. But when a higher energy is used, sufficient to examine denser areas or to penetrate something like a cast in orthopedic imaging, the risk of scatter increases, and grids become more important to distinguish between various densities and structures within the body.
In the context of pediatric versus adult radiography, whether to use a grid or not will depend on a case-by-case basis, determined by the patient's size, the part of the body being imaged, and the diagnostic need applying the concept of radiation protection and ALARA (As Low As Reasonably Achievable) principles to minimize unnecessary radiation exposure. Pediatirc radiography usually requires careful consideration of radiation dose and image quality due to the increased sensitivity of children to ionizing radiation.