I think Risk/Benefit ratio is something only used to decide at the beginning when the company has to decide whether or not to go ahead with the project. Whether the benefit is worth the risk or is Risk to high for the benefit the company will make. It is something really important for a business to survive.
Other Risk we talk about is what risk does the medical device manufactured poses and this are risk which needs to be tackled if not removed. This risk needs to identified from time to time through out the project management phase.And this are the only one which can be reduced.