Which four elements are the primary exposure factors in radiography?

• A. mA, kVp, exposure time, distance
• B. mA, time, filtration, distance
• C. kVp, filtration, distance, grid
• D. mA, kVp, filtration, screen speed

Answer: (A)

The main concept here is identifying the four factors you actively adjust to set the X-ray exposure. The four primary exposure factors are mA, exposure time, kVp, and distance. mA controls the tube current, and when combined with exposure time you get the total exposure in mAs. kVp determines the energy of the X-ray beam, affecting how well it penetrates and the resulting image contrast and patient dose. Distance (the source-to-image distance) changes beam intensity via the inverse square law—moving farther away lowers exposure unless mA or time is increased to compensate. These four together establish both the quantity and quality of photons reaching the image receptor.

Filtration, grids, and screen speed influence beam quality, scatter, contrast, and receptor sensitivity, but they are not considered the primary exposure factors you set to produce the radiographic exposure.