The primary exposure factors in radiography are:

• A. SID
• B. Filtration
• C. kVp and mAs
• D. Grid

Answer: (C)

Controlling the image receptor exposure comes down to two settings: kVp and mAs. Kilovoltage peak determines the energy and penetrating power of the X-ray beam, which influences how easily photons pass through tissues and also affects image contrast. Higher kVp makes the beam more penetrating and lowers contrast, while lower kVp increases contrast but requires more exposure to keep the image visible. The milliampere-seconds control how many photons are produced in the beam; increasing mAs increases receptor exposure (darker image), and decreasing mAs decreases exposure. Filtration, grids, and distance (SID) affect exposure and quality but do not set the exposure level themselves—the primary controls are the beam’s energy (kVp) and the photon quantity (mAs).