Final answer:
Changing a 4-inch collimated field to a 14-inch field increases radiation exposure and image density due to the inverse square law, similar to how a larger telescope aperture allows more light and produces a brighter image.
Step-by-step explanation:
When a 4-inch collimated field is changed to a 14-inch collimated field, with no other changes, there is a significant increase in the amount of radiation exposure to the film or image receptor. This is explained by the inverse square law, which states that the intensity of radiation exposure is inversely proportional to the square of the distance from the source. In this case, increasing the size of the collimated field allows more radiation to pass through, thus increasing the exposure and resulting in a higher image density or increased IR exposure. This concept is analogous to how the aperture of a telescope affects the amount of light it can collect; the larger the aperture, the more light it collects, and hence, the brighter the image.
Therefore, by increasing the size of the collimated field from 4 inches to 14 inches, more radiation exposes the film, leading to a radiographic image with more density. This increase can be understood in terms of the area of radiation exposure, which is proportional to the square of the diameter of the collimation field. Applying this principle, the area increases significantly when the diameter is increased, just as the amount of light increases when a telescope's aperture is enlarged.