Page 401 - Biomedical Engineering and Design Handbook Volume 2, Applications

SURGICAL SIMULATION TECHNOLOGIES 379

enhance the user experience. Most virtual environment-based medical simulations are in the form of
nonimmersive virtual environments. This is mostly as a result of the nature of the surgical procedures
being simulated, such as minimally invasive surgery. The limitations of the existing state-of-the-art
user interface hardware, such as head-mounted displays and haptic interface devices, also limit the
application of immersive virtual environments in surgical simulation. The most striking application
of augmented reality in surgical simulation is to give the surgeon “x-ray vision,” by projection of
interior anatomical structures, such as the location of a tumor, obtained from preoperative medical
images onto the surgical scene where these structures are not readily visible.
There are several terms that are used somewhat interchangeably, including virtual reality, arti-
ficial reality, virtual worlds, and virtual environments. Among these, the terms virtual reality and
virtual environments are the most commonly used. Virtual reality is the term typically used by the
popular press, while virtual environments is the term used by the scientific community. This is
partly to emphasize the fact that a virtual environment does not necessarily try to replicate the reality,
and also to distance the field from the hype that surrounds the term virtual reality in the popular
press. 4

13.2 DEVELOPMENTS IN SIMULATION-BASED
MEDICAL EDUCATION

A variety of simulation approaches and tools have proliferated in the past 20 years. These include the
sophisticated advanced cardiac life-support training systems, complex task trainers for endoscopic
and catheter-based procedures, ultrasound simulators, and computer-controlled mannequin-based inter-
vention simulators. Virtual environment-based devices are also under intense development, and several
systems are commercially available.
The Harvey cardiology patient simulator (CPS), a life-size mannequin capable of simulating the
bedside findings of a wide variety of cardiovascular conditions, may be the most widely used and
most thoroughly studied and validated simulator-supported part-task skills trainer. Harvey is capable
of replicating 27 physical conditions (2 normal conditions and 25 cardiovascular diseases), and is
used for individual, small group, and large group instruction with or without the presence of a
teacher. Harvey and its complementary computer-based curriculum (UMedic) have recently become
key features of the curricula at every medical school in the United Kingdom.
Virtual environment-based surgical simulators for surgical training has been proposed in the early
5
1990s. However, technological limitations, and lack of well-controlled clinical trials that demon-
strate the effectiveness of such systems, limited the initial adoption of virtual environment-based
surgical training simulators. By early 2000s, randomized double-blind studies demonstrating the
efficacy of virtual environment-based surgical training simulators started to appear in the literature. 6
In 2004, the U.S. Food and Drug Administration’s (FDA) approval of a new device (carotid artery
stenting systems) included a requirement for training of physicians, which, as part of it, incorporates
7
virtual environment-based simulators. Currently, training on virtual environment-based simulators
is not accepted as an alternative to actual procedural experience, but instead, considered as an inte-
gral part of a comprehensive curriculum designed to meet specific educational goals.

13.2.1 Applications of Virtual Environment-Based
Surgical Simulators
Virtual environment-based training simulators have been developed for various surgical applications.
8
Simulators can be grouped into general categories based on the nature of the surgical intervention :
Needle and Catheter-Based Procedures. Needle and catheter-based procedures generally have
simple user interfaces with very restricted interaction with biological tissue. As a result, the simula-
tors constructed for these procedures require less sophisticated methods to generate sufficient visual