Increasing which of the following factors will decrease the density of a radiograph?

To understand why increasing the focal spot-object distance will decrease the density of a radiograph, it's essential to consider the relationship between this distance and the intensity of the radiation that reaches the film or digital sensor.

When the focal spot-object distance is increased, the X-ray beam spreads out more, leading to a decrease in the number of photons that actually reach the film. This phenomenon is explained by the inverse square law, which states that the intensity of radiation is inversely proportional to the square of the distance from the source. As the distance increases, the intensity diminishes, resulting in fewer X-rays depositing energy on the radiographic film. Consequently, this results in a lighter or less dense image.

In contrast, factors such as milliampere, time, and kilovoltage (KvP) directly increase the number of X-ray photons produced or their energy, contributing to a higher density radiograph. Therefore, increasing the focal spot-object distance will reduce the amount of radiation exposure the film receives, leading to a decrease in its overall density.