Surgery simulations to date have largely been created through the
development of dedicated applications requiring considerable programming
and computer graphics skills. The expansion of surgery simulation-based
medical education has been limited by these steep educational and
experience requirements. To lower these barriers and enable rapid
expansion of surgery simulation-based training, the Teleos medical
education system has been created to allow instructional surgery
simulation scenarios to be created without programming.

The technology underlying the system is derived from High
Techsplanations experience in creating custom surgery simulation virtual
environments. The system, which at present runs on Silicon Graphics
workstations, consists of two applications: a simulation designer and a
simulation engine. The designer is used to create the content of each
surgery scenario, such as the definition of anatomic and tool geometry
and the specification of visual and physical properties. The simulation
engine is used to interact with the surgery scenarios and can used either
along with the designer program or as a stand-alone application.

Typically, the designer program will be used by medical content
experts while the trainee will interact with, but not create new, surgery
scenarios. The simulation engine allows the trainee to use spatial motion
tracking and force feedback devices, along with stereo viewing, to
provide an experience that parallels the actions of the actual surgery
they are practicing.

A surgery scenario may be created by using existing medical imagery,
such as MR, CT, or the Visible Human Project photographic data, as a
template or the scene may be developed independently. The surgery scene
consists of several types of entities including physically-based tubes,
polyhedra, volumetric data, and particle systems. Tubes are the primary
entity of a simulation and embody a spatial spline formulation having
Newtonian physics properties. They have the ability to be deformed in
real-time through contact with tools, other tubes, and additional forces.

Tubes can be developed from the medical imagery templates as well as
independently created. Polyhedra are nondeformable objects that may be
imported from standard file formats and manipulated to be properly scaled
and placed into the surgical scene. Volumetric data is derived from the
same imagery used for templates and can be used to view the interior of
objects by taking advantage of the unique 3D volume texture rendering
capabilities of Silicon Graphics workstations.

Once the geometry of a surgical scene has been defined, the
interconnections between the objects and the physical properties of the
tubes are specified. Surgical tools are selected from a group of
previously created tools or a new tool can be created. Lastly, the
simulation designer refines the response of the simulation by testing and
adjusting the interconnections and their properties.

Once a simulation is complete, all that needs to be provided to the
trainee is the data describing the scene and the simulation engine. The
simulation engine allows a simulation to be paused or saved for later
use. The activities of the simulation user can also be saved for later
review. An additional feature of the simulation engine is the ability to
save ‘snapshots’ for the simulation in progress that can be viewed with
the recently developed 3-D Internet web browsers.

With the availability of the Teleos Medical Education System, the first
step has been made to lower the threshold of entry to simulation-based
surgery education. This will continue to fall, as the simulation
abilities of the system are further enhanced, a growing number of pre-
defined surgery scenes become available, and the cost of computer
hardware decreases. More information on Teleos is available at Web site
<http://www.ht.com>.