CAMRT Radiography Practice Exam

Which factor is primarily responsible for controlling radiographic contrast in imaging?

1. mAs

2. kVp

3. Exposure time

4. Film type

The correct answer is: kVp

The primary factor that controls radiographic contrast in imaging is kVp, or kilovoltage peak. kVp determines the energy of the X-ray beam and influences the degree of penetration of the X-rays through the tissue. Higher kVp settings result in X-rays with greater energy, which can penetrate more dense tissues, leading to a wider range of densities on the radiograph. This range of densities is what creates contrast in the image; therefore, by adjusting the kVp, radiographers can enhance the contrast between different anatomical structures. Contrast is vital for visualizing details in radiographs since it differentiates between varying tissue types based on their atomic composition and density. When kVp is increased, there is a greater penetration, which can result in lower contrast if not properly adjusted since the differences between various tissues may be diminished. Conversely, using a lower kVp results in more absorption and, therefore, higher contrast, but at the risk of under-penetrating denser tissues. While factors such as mAs (milliamperes-seconds), exposure time, and film type can influence overall image quality and density, kVp is the primary control for contrast specifically. Thus, adjusting the kVp is critical in optimizing contrast for the specific anatomical structures being