Any way to tell when someone last saw a topic?

[Jade Elizabeth]

So I have been really evil and made it so a topic always shows at the top of staff unread lists. I know it's annoying as hell but it's also helpful haha.

Anyway I wanted the "new" icon to display if the staff member in question has not viewed the topic in the last week.

Can I do that? What should I wrap around the line for the new icon to make it happen?