Power
It's a pretty powerful thing, catching life-threatening diseases or fetal complications before they can really be an issue. It's like playing detective before the crime has even happened. Think of it that way, and before you know it, you'll be raising your fists to the sky and cackling.
However, if you're thinking of power in the more real-world sense, then you might want to stop that cackling. When you start out, you won't have a lot of influence in your hospital or your field. However, once you've risen up the ranks a little, your power levels will go up. RPG style. Except there'll be fewer magical items and more paperwork.
If you become an administrator or manager, you'll be in charge of the sonography department's policies and employees—in other words, you'll be able to ensure that your facility and technicians are the best around.