Today the answer is board certification. Knowledge can be tested by means of paper-and-pencil examinations, but proficiency in operative skills cannot be demonstrated in this way. As a result, individual residency programs are left to judge a physician competent in the operating room.
VE simulators offer some hope for standardizing the surgical accreditation process. For example, a more sophisticated version of the abdominal simulator developed by Satava (1993b) could offer a set of standardized tests for laparoscopic procedures. The ability to track the instruments would enable the National Board of Medical Examiners (or a similar governing body) to monitor performance during a given procedure and to document the types and frequency of errors made, thus providing some uniform means of assessing surgical skills across programs.
An actual medical operation is never performed in the abstract—it is performed on a specific individual whose precise physical dimensions are unique and whose anatomy almost certainly deviates from those found in anatomy textbooks. Thus, to a certain extent, a surgeon confronts surprises every time he or she undertakes an operation.
VE-based surgical planning aids offer a way to reduce the uncertainty. In principle, imaging data for the patient could be used to update a generic digital human model, allowing the surgeon to understand more fully the specifics of the individual. The surgeon could then explore freely various approaches to solving a surgical problem on the VE simulator and could practice the operation if required.
Such an application is a promise for the long term. However, Jolesz and his colleagues (Gleason, 1993) have developed an augmented-reality system for video registration of brain tumors to aid in the planning and performance of surgical resection. In this system, the mass is imaged using either CT or MRI, a three-dimensional construct is created, and the image is projected over the patient's head to plan the optimal site of skin incision and bone flap to expose the tumor. This program is then taken into the operating room to provide a reference map for the surgeons during the resection. Thus, the surgeon is able to consult the image at any time to assess the remaining tissue and the extent of further excision.
A model of the lower extremity envisioned by Mann (1985) and designed by Delp (Delp et al., 1990) is an example of using virtual reality to test various procedures. This model allows the surgeon to "perform" the planned surgery, and then simulate a number of years of walking or other normal activity. The altered model can be reanalyzed at the end of the simulated activity period and the outcome of the procedure evaluated.