In radiographic imaging, which factor primarily affects the contrast of an image?

The primary factor that affects the contrast of a radiographic image is the kilovolt peak (kVp). Contrast refers to the difference in density between the various parts of the image, which allows for differentiation of tissues and structures within the body.

When kVp is increased, the energy of the x-ray beam is also increased, resulting in greater penetration of the beam through the body. This creates a wider range of exposure levels on the imaging receptor, ultimately leading to greater contrast between different types of tissues, especially when differentiating between those that have similar densities.

On the other hand, filtration primarily affects the quality of the x-ray beam by removing low-energy photons that do not contribute to the imaging process. While mAs (milliampere-seconds) is crucial for determining the overall density of the image, it doesn't have the same direct effect on contrast as kVp does. Lastly, the source-to-image distance (SID) influences the size and sharpness of the image rather than its contrast. Therefore, kVp is the key factor for affecting image contrast in radiographic imaging.