Final answer:
Radiation dose rate at the input phosphor is directly proportional to image brightness, meaning an increased dose rate results in a brighter image.
Step-by-step explanation:
The radiation dose rate at the input phosphor is directly related to image brightness. This means that as the dose rate of radiation increases, the brightness of the resulting image also increases. When considering the biological effects of ionizing radiation, the dose, measured in rads, and hence the brightness, is proportional to the amount of ionization and the energy deposited in the tissue. Furthermore, the intensity of electromagnetic (EM) radiation, which corresponds to the number of electrons ejected per unit time, is proportional only to the intensity of the EM radiation. This is comparable to the way light intensity (and thus brightness) from a light source spreads out and diminishes with distance, as it is inversely proportional to the square of the distance from the source.