Final answer:
A radiographer should routinely use a small focal spot when imaging extremities because it increases spatial resolution.
Step-by-step explanation:
When imaging extremities, a radiographer should routinely use a small focal spot because it increases spatial resolution. A small focal spot produces a sharper image with greater detail, making it easier to visualize small structures in the extremities, such as bones or soft tissues. This can help with diagnosing fractures, tumors, or other abnormalities.