Which factor is adjusted to increase the contrast in radiographic images?

To enhance the contrast in radiographic images, the kilovoltage peak (kVp) is the factor that is adjusted. The kVp controls the quality, or penetrating power, of the X-ray beam. Higher kVp settings result in a greater average energy of the X-ray photons, which can penetrate tissues more effectively. This increased penetration means that denser structures produce fewer X-rays, leading to darker areas on the film, while less dense structures allow more X-rays to reach the film, resulting in lighter areas.

As a result, adjusting the kVp directly influences the contrast in the image by altering the differential absorption of X-rays from different tissues. Lowering the kVp can increase contrast but may also result in a higher radiation dose and increased scattering effects, leading to a less desirable image quality.

The other factors mentioned—time, distance, and milliamperage (mA)—affect exposure and image density but do not fundamentally alter the contrast in the same way kVp does. Time and mA primarily influence the quantity of X-ray photons produced, while distance affects the intensity of the X-ray beam that reaches the image receptor, but neither directly impacts the sharpness of the contrast in radiographic images.