Internal Services Cost Transfers

How do the hospital users out there handle internal transfers from department to department? We have many internal services that get requested by our PIs that we then need to perform a cost transfer from the service department to the PI. Our service departments would be similar to many service departments at a hospital (Histology, Radiology, Pharmacy, etc.). The issue that we are faced is that many of these transfers happen monthly and we want to streamline the process while capturing transactional data. Do hospitals charge these kinds of services directly to patient accounts or do they charge the department that processed the original request for the patient? Is there a solution that someone might be currently using that would possible help us? It would be nice if the system could process a request from the originating department for the internal services, and then allow the system to process the transfer once the service is delivered. This seems like a simple process or request but it seems to have confused many. All thanks for the any help.