By Douwe Miedema WASHINGTON (Reuters) - The top U.S. derivatives regulator is considering whether the Bitcoin virtual currency should be subject to its rules, a top official at the agency said. Bart Chilton, one of five commissioners at the Commodity Futures Trading Commission, said he had asked staff to explore whether consumers needed more protection from any mishaps with Bitcoin, whose value collapsed last month. "Here's what I know for sure: we could regulate it if we wanted. That is very clear," Chilton told Reuters in an interview on Monday. ...