To back my case, I look at two examples that employ a clinical RE approach... The former uses a Brownfield approach by starting with an existing clinical process, cognitive rehabilitation, and then defining an RE process that fits. The latter uses a Greenfield approach that postulates a new clinical RE process that focuses on the problems some of us have using digital darkroom tools.
http://www.cs.wustl.edu/icse05/ConferenceProg...


Every factory is unique.

It goes without saying that we are able to respond to differing requirements and individual production philosophies and integrate them into our planning processes. To identify the best possible solution our first step is to create a variety of green field concepts. This can be for new, updated or expanded projects, and the approach allows us to minimise the gap between existing systems and the green field approach – with the appropriate level of flexibility, leaving options open for future changes in terms of capacities, structures and alternative manufacturing systems.
http://www.ingenics.de/en/divisions/factory_p...
(equivalent German page "kann eine Integration in bestehende Strukturen qualifiziert erfolgen und das Delta zum Optimum auf der grünen Wiese minimiert werden.")

In order of my personal preference: green-field/green field/greenfield/Greenfield approach. All are possible, however.