When selecting the target angle in radiography, what effect does a larger angle have on the effective focal spot size?

When selecting the target angle in radiography, a larger angle leads to an increase in the effective focal spot size. This occurs because the effective focal spot is influenced by the geometry of the x-ray tube target and the angle at which x-rays are emitted.

As the target angle becomes larger, the projection of the actual focal spot onto the image receptor becomes wider and is perceived as a larger effective focal spot. This results in a decrease in spatial resolution because a larger focal spot means increased penumbra effects, which can lead to less sharp images.

In practical terms, a larger effective focal spot size can lead to a trade-off where radiologists may gain the ability to handle higher beam intensity and heat dissipation, but at the cost of image quality due to the blurriness introduced by the increased size of the focal spot on the image receptor.