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Methods Inf Med 5/2003
mainly into three classes: surgery training,
surgery planning and augmented reality for
surgery sessions in open surgery, endosco-
py, and radiosurgery. A couple of years
later, the scope of VR applications in medi-
cine has broadened to include neuropsy-
chological assessment and rehabilitation
[6, 7].
In recent years, VR has generated both
great excitement and great confusion.
These factors are evident in the extensive
material published in both scientific and
popular press, and in the unrealistic expec-
tations on the part of the health care pro-
fessionals (8). In this paper we try to outline
the current state of research and technolo-
gy that is relevant to the development of
VEs in medicine. Moreover, we discuss the
clinical principles, technological devices
and safety issues associated with the use of
virtual reality in medicine.
2. The Role of VR
in Health Care
2.1 The Two Faces of VR
in Health Care
For many health care professionals VR is
first of all a technology. Since 1986, when
Jaron Lamier used the term for the first
time, VR has been usually described as a
collection of technological devices: a com-
puter capable of interactive 3D visualiza-
tion, a head-mounted display and data
gloves equipped with one or more position
trackers. The trackers sense the position
and orientation of the user and report that
information to the computer that updates
(in real time) the images for display.
However, the analysis of the different
VR applications clearly shows that the
focus on technological devices is different
Applications of Virtual Environments in Medicine*
G. Riva
Applied Technology for Neuro-Psychology Lab., Istituto Auxologico Italiano, Milan, Italy
1. Introduction
As recently noted by Satava and Jones [1],
the advantages of virtual environments
(VEs) to health care can be summarized in
a single word: revolutionary. Since the de-
velopment of methods of electronic com-
munication clinicians have been using in-
formation and communication technolo-
gies in health care: telegraphy, telephony,
radio and television have been used for dis-
tance medicine since mid 19
th
century [2].
However, rapid and far-reaching techno-
logical advances are changing the ways in
which people relate, communicate, and live.
Technologies that were hardly used ten
years ago, such as the Internet, e-mail, and
video teleconferencing are becoming famil-
iar methods for diagnosis, therapy, educa-
tion and training. However, the possible im-
pact of virtual reality (VR) on health care is
even higher than the one offered by the
new communication technologies [3]. In
fact, VR is a technology, a communication
interface and an experience [4]. This is why
the research in the virtual reality field is
moving fast. If we check the two leading
clinical databases – MEDLINE and
PSYCINFO – using the “virtual reality”
keyword we can find 951 papers listed in
MEDLINE and 708 in PSYCINFO (all
fields query, accessed June 9, 2003).
From the analysis of the retrieved pa-
pers we can find that the first health care
applications of VR started in the early ’90s
by the need of medical staff to visualize
complex medical data, particularly during
surgery and for surgery planning [5]. Actu-
ally, surgery-related applications of VR fall
Summary
Objective: This paper intends to investigate the role
of virtual reality (VR) in medicine. In particular it out-
lines the current state of research and technology that
is relevant to the development of effective virtual
environments in medicine.
Method: After describing the two different visions of
VR we can find in medicine – the presentation of
virtual objects to all of the human senses in a way
identical to their natural counterpart, and a new hu-
man-computer interaction paradigm in which users are
active participants within a computer-generated three-
dimensional virtual world – the paper presents some
of the most interesting applications actually developed
in the area. Finally, it discusses the clinical principles,
technological devices and safety issues associated
with the use of VR in medicine.
Conclusions: The possible impact of VR on health care
could be even higher than the one offered by the new
communication technologies like Internet. In fact,
VR is at the same tima technology, a communication
interface and an experience: a communication inter-
face based on interactive 3D visualization, able to col-
lect and integrate in single real-like experience differ-
ent inputs and data sets. However, significant efforts
are still required to move VR into commercial success
and therefore routine clinical use.
Keywords
Virtual reality, medical education, surgical simulation,
neuropsychological rehabilitation
Methods Inf Med 2003; 42: 524–34
Methods MIM 0161
* This paper is an updated version of an invited
review paper that appeared in Haux, R., Kuli-
kowski, E. (eds.) (2003). IMIA Yearbook of
Medical Informatics 2003: Quality of Health
Care: The Role of Informatics, pp. 159-69,
Stuttgart: Schattauer.
Applications of Virtual Environments in Medicine
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Methods Inf Med 5/2003
according to the goals of the health care
provider.
For instance, Rubino et al. [9], McCloy
and Stone [10], and Székely and Satava [11]
in their reviews share the same vision of
VR:“a collection of technologies that allow
people to interact efficiently with 3D com-
puterized databases in real time using their
natural senses and skills” [10]. This defini-
tion lacks any reference to head mounted
displays and instrumented clothing such as
gloves or suits. In fact, less than 20% of VR
health care applications in medicine are ac-
tually using any immersive equipment.
However, if we shift our attention on be-
havioral sciences, where immersive devices
are used by more than 50% of the applica-
tions,VR is described as “an advanced form
of human-computer interface that allows
the user to interact with and become im-
mersed in a computer-generated environ-
ment in a naturalistic fashion” [12]. In fact,
to achieve the feeling of “being there”
the VR applications use ■f specialized de-
vices as head-mounted displays, tracking
systems, earphones, gloves, and sometimes
haptic-feedback devices.
These two definitions underline two dif-
ferent visions of VR. For physicians and
surgeons, the ultimate goal of VR is the
presentation of virtual objects to all of the
human senses in a way identical to their
natural counterpart [11]. As noted by Sata-
va and Jones [1], as more and more of the
medical technologies become information-
based, it will be possible to represent a pa-
tient with higher fidelity to a point that the
image may become a surrogate for the pa-
tient – the medical avatar. In this sense, an
effective VR system should offer real-like
body parts or avatars that interact with ex-
ternal devices such as surgical instruments
as near as possible to their real models.
For clinical psychologists and rehabilita-
tion specialists the ultimate goal is radically
different [13, 14]. They use VR to provide a
new human-computer interaction para-
digm in which users are no longer simply
external observers of images on a computer
screen but are active participants within a
computer-generated three-dimensional vir-
tual world. Within the VE the patient has
the possibility of learning to manage a
problematic situation related to his/her dis-
turbance. The key characteristics of virtual
environments for these professionals are
both the high level of control of the interac-
tion with the tool without the constraints
usually found in computer systems, and the
enriched experience provided to the pa-
tient [12]. Virtual environments are highly
flexible and programmable. They enable
the therapist to present a wide variety of
controlled stimuli, such as a fearful situa-
tion, and to measure and monitor a wide
variety of responses made by the user. This
flexibility can be used to provide systemat-
ic restorative training that optimize the de-
gree of transfer of training or generaliza-
tion of learning to the person’s real world
environment [15].
Moreover, virtual reality systems open
the input channel to the full range of hu-
man gestures: in rehabilitation it is possible
to monitor movements or actions from any
body part or many body parts at the same
time. On the other side, with disabled pa-
tients feedbacks and prompts can be trans-
lated into alternate and/or multiple senses
[16].
2.2 VR as Communication Interface
As we have just seen, if we consider VR
mainly as a technology we have two differ-
ent visions of VR related to the final goal of
the health care professional. But what these
two visions have in common?
The starting point for answering to this
question is a definition of VR presented by
Heim. According to this author [17], VR is
“an immersive, interactive system based on
computable information… an experience
that describes many life activities in the in-
formation age” (p. 6). In particular he de-
scribes the VR experience around its “three
I’s”: immersion, interactivity and informa-
tion intensity. Developing this position,
Bricken [18] identifies the core characteris-
tic of VR in the inclusive relationship
between the participant and the virtual en-
vironment, where direct experience of the
immersive environment constitutes com-
munication. According to this position, VR
can be considered as the leading edge of a
general evolution of present communica-
tion interfaces like television, computer
and telephone [19, 20]. The main character-
istic of this evolution is the full immersion
of the human sensorimotor channels into a
vivid and global communication experience
[21].
Following this approach, it is also pos-
sible to define VR in terms of human expe-
rience [22] “a real or simulated environ-
ment in which a perceiver experiences
telepresence”, where telepresence can be
described as the “experience of presence in
an environment by means of a communica-
tion medium” (pp. 78-80).
This position better clarifies the possible
role of VR in medicine: a communication
interface based on interactive 3D visualiza-
tion, able to collect and integrate different
inputs and data sets in a single real-like ex-
perience. It is up to the health care provid-
er to decide if the VR application will be
more focused on the integration of differ-
ent data sets or on the realism of the virtu-
al experience. Considering VR as a commu-
nication interface also helps health care de-
velopers to focus their efforts.
Most of the work in this area is trying to
improve the efficacy of a VE by providing
to the user a more “realistic” experience,
such as adding physical qualities to virtual
objects or improving the graphical resolu-
tion. But is it really so important for the ef-
fectiveness of a medical VE this focus on
the graphical characteristics?
Probably, apart from some high-end sur-
gical applications, the answer is no. More
than the richness of available images, the
efficacy of a virtual environment depends
on the level of interaction/interactivity
which actors have in both “real” and simu-
lated environments [23]. According to Sas-
try and Boyd [23] a VE, particularly when it
is used for real world applications, is effec-
tive when “the user is able to navigate, se-
lect, pick, move and manipulate an object
much more naturally” (pp. 235). In this
sense, emphasis shifts from quality of image
to freedom of interaction, from the graphic
perfection of the system to the affordances
provided to the users in the environment
[24]. Further, as the underlying enabling
technologies continue to evolve and allow
us to design more useful and usable struc-
tural virtual environments the next impor-
tant challenge will involve populating these
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environments with virtual representations
of humans (avatars) [25].
This is possible because the key charac-
teristic of VR, differentiating it from other
media or communication systems, is the
sense of presence [26, 27]. What is pres-
ence? Even if usually presence is defined as
the “sense of being there” [22], or as the
“feeling of being in a world that exists out-
side of the self” [28], it is now widely ac-
knowledged that presence can be consid-
ered as a neuropsychological phenomenon
[20, 26, 29-33]. In particular, Riva and Wa-
terworth described presence as a defining
feature of self, related to the evolution of a
key feature of any central nervous system
[28]: the embedding of sensory-referred
properties into an internal functional space.
More in particular, without the emergence
of the sense of presence it is impossible for
the nervous system to separate between an
external world and the internal one. If in
simple organisms, this separation involved
only a correct coupling between percep-
tions and movements, in humans it also
requires the shift from meaning-as-com-
prehensibility to meaning-as-significance.
Meaning-as-comprehensibility refers to the
extent to which the event fits with our view
of the world (for example, as just, controlla-
ble, and nonrandom) whereas meaning-as-
significance refers to the value or worth of
the event for us [34]. Following this point,
contributions to the intensity of the sense
of presence come from three layers of the
self recently defined by Damasio [35]: pro-
to self, core self and autobiographical self.
The more the three layers are integrated
(focused on the same events) the stronger
the intensity of the presence feeling [28].
This means that having two equally stimu-
lating virtual environments, humans are
more present in the one more relevant to
their own goals.
This approach has recently received
the status of international standard,
through the International Organization for
Standardization’s ISO 13407 “Human cen-
tered design for interactive systems”. Ac-
cording to the ISO 13407 standard [36],
human-centered design requires:
●
the active involvement of users;
●
clear understanding of use and task re-
quirements;
●
appropriate allocation of function;
●
the iteration of design solutions;
●
a multi-disciplinary design team;
and it is based around the following proc-
esses:
●
understand and specify the context of
use;
●
specify the user and organizational re-
quirements;
●
produce designs and prototypes;
●
carry out user-based assessment.
A sample of VE developed using the ISO
13407 guidelines is the IERAPSI surgical
training system [10, 37].
3. Applications of Virtual
Reality in Medicine
3.1 Medical Education
The teaching of anatomy is mainly illustra-
tive, and the application of VR to such
teaching has great potential [38]. Through
3-D visualization of massive volumes of in-
formation and databases, clinicians and stu-
dents can understand important physiolog-
ical principles or basic anatomy [39]. For
instance, VR can be used to explore the or-
gans by “flying” around, behind, or even in-
side them. In this sense VEs can be used
both as didactic and experiential educa-
tional tools, allowing a deeper understand-
ing of the interrelationship of anatomical
structures that cannot be achieved by any
other means, including cadaveric dissec-
tion.
A significant step towards the creation
of VR anatomy textbooks was the acquisi-
tion of the Visible Human male and female
data made in August of 1991 by the Univer-
sity of Colorado School of Medicine [40].
The Visible Human female data set con-
tains 5189 digital anatomical images ob-
tained at 0.33-mm intervals (39 Gbyte).The
male data set contains 1971 digital axial an-
atomical images obtained at 1.0-mm inter-
vals (15 Gbyte) [41]. Actually, the US Na-
tional Library of Medicine in partnership
with other US government research agen-
cies has begun the development of a tool
kit of computational programs capable of
automatically performing many of the basic
data handling functions required for using
Visible Human data in applications [42].
The National Library of Medicine made
the data sets available under a no-cost
license agreement over the Internet. And
this allowed the creation of a huge number
of educational VEs. In their recent edited
book Westwood and colleagues [43] report
more than ten different educational and
visualization applications.
In the future we can expect the develop-
ment of different VR dynamic models illus-
trating how various organs and systems
move during normal or diseased states, or
how they respond to various externally ap-
plied forces (e.g., the touch of a scalpel).
Apart from anatomical training, VR has
been used for teaching the skill of perform-
ing a 12-lead ECG [44]. In all these cases,
VR simulators allowed the acquisition of
necessary technical skills required for the
procedure.
3.2 Surgical Simulation
and Planning
Surgeons know well that in training there is
no alternative to hands-on practice. How-
ever, students wishing to learn laparoscopic
procedures face a tough path [45]: usually
they start using laparoscopic cholecystecto-
my trainers consisting of a black box in
which endoscopic instruments are passed
through rubber gaskets. After, the students
begin practicing these techniques on inani-
mate tissues, when allowed by their cost
and availability. Obviously, there is a sub-
stantial difference for students between
training with artificial or inanimate tissues
and supervised procedures on real patients.
This is why in early 1990s different research
teams tried to develop VE simulators [46,
47]. The science of virtual reality provides
an entirely new opportunity in the area of
simulation of surgical skills using comput-
ers for training, evaluation, and eventually
certification [48]. However the first simula-
tors were limited by low-resolution graph-
ics, the lack of tactile input and force feed-
back and the lack of realistic deformation
of organs. In the last years a new generation
Applications of Virtual Environments in Medicine
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Methods Inf Med 5/2003
of simulator has appeared that has shown
improved training efficacy over traditional
methods [49, 50, Schijven, 2003 #1455].
For instance, a randomized trial using the
Minimally Invasive Surgery Training-Virtu-
al Reality (MIST-VR) trainer [51, 52]
showed that VR simulation was effective
in training the novice to perform basic
laparoscopic skills (see Fig. 1).
Another typical use of visualization ap-
plications is the planning of surgical and
neuro-surgical procedures [53-55]. The
planning of these procedures usually relies
on the studies of series of two-dimensional
MR (Magnetic Resonance) and/or CT
(Computer Tomography) images, which
have to be mentally integrated by surgeons
into a three-dimensional concept. This
mental transformation is difficult, since
complex anatomy is represented in differ-
ent scanning modalities, on separate image
series, usually found in different sites/de-
partments. A VR-based system is capable
of incorporating different scanning modal-
ities coming from different sites providing a
simple to use interactive three-dimensional
view.Within the Virtual Collaborative Clin-
ic project, NASA researchers developed
Cyberscalpel, a typical VR-based surgical
system for planning and practice [56]. To
plan the operation of a patient with a can-
cer of the jaw, the upper and lower jaws
were reconstructed using Cyberscalpel
starting from a CT scan. The scan was re-
duced to 20,000 polygons and the final
model used to prove how fibular bone
could be sectioned to mimic and replace
the jaw pieces.
Finally, the increased pressure to reduce
the use of animals in technical training has
led to use VR in teaching microsurgery
[57].This new technology may prove to be a
cost-effective, portable, and nonhazardous
way forward in microsurgical training.
3.3 Virtual Endoscopy
Every year the screening for cancer re-
quires the performance of over 2 million
video colonoscopic procedures. However,
these procedures are not perfect:
●
all endoscopic procedures are invasive;
●
the patients are subject to complications
such as perforation, bleeding, etc.
●
the cost for a typical colonoscopy is sig-
nificant.
To overcome these problems, different re-
searchers are investigating the possibility of
virtual endoscopy [9, 58].Virtual endoscopy
is a new procedure that fuses computed to-
mography with advanced techniques for
rendering three-dimensional images to pro-
duce views of the organ similar to those ob-
tained during “real” endoscopy. A virtual
endoscopy is performed by using a stan-
dard CT scan or MRI scan [1], reconstruct-
ing the organ of interest into a 3D model,
and then performing a fly through it. Typi-
cal examples include the colon, stomach,
esophagus, tracheo-bronchial tree (bron-
choscopy), sinus bladder, ureter and kid-
neys (cystoscopy), pancreas or biliary tree
[59].
Virtual endoscopy is completely non-in-
vasive and thus without known complica-
tions [60]. The actual cost is less of tradi-
tional endoscopy, since it is performed in
the same place and manner as all imaging
modalities, utilizes the same staff, and has
no consumable materials.
3.4 VR in Neuro-Psychological
Assessment and Rehabilitation
VR is starting to play an important role in
clinical psychology [61, 62], that is expected
to increase in the next years.According to a
recent positioning paper on the future of
psychotherapy [63], the use of VR and
computerized therapies are ranked respec-
tively 3
rd
and 5
th
out of 38 psychotherapy
interventions that are predicted to increase
in the next 10 years.
In most VEs for clinical psychology VR
is used to simulate the real world and to as-
sure the researcher full control of all the
parameters implied. VR constitutes a high-
ly flexible tool, which makes it possible to
program an enormous variety of proce-
dures of intervention on psychological dis-
tress. The possibility of structuring a large
amount of controlled stimuli and, simulta-
neously, of monitoring the possible re-
sponses generated by the user of the virtual
world offers a considerable increase in the
likelihood of therapeutic effectiveness, as
compared to traditional procedures [20]. In
particular, a key advantage offered by VR
is the possibility for the patient to manage
successfully a problematic situation related
to his/her disturbance. Using VR in this
way, the patient is more likely not only to
gain an awareness of his/her need to do
something to create change but also to ex-
perience a greater sense of personal effica-
cy.
In general, these techniques are used as
triggers for a broader empowerment proc-
ess. In psychological literature empower-
ment is considered a multi-faceted con-
struct reflecting the different dimensions of
being psychologically enabled, and is con-
ceived of as a positive additive function of
the following three dimensions [64]:
●
perceived control: includes beliefs about
authority, decision-making skills, avail-
ability of resources, autonomy in the
scheduling and performance of work,
etc;
●
perceived competence: reflects role-mas-
tery, which besides requiring the skillful
accomplishment of one or more as-
signed tasks, also requires successful
coping with non-routine role-related sit-
uations;
Fig. 1 Minimally Invasive Surgery Training-Virtual Real-
ity (MIST-VR) trainer (Mentice Medical Simulation AB,
Gothenburg, Sweden)
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Methods Inf Med 5/2003
●
goal internalization: this dimension cap-
tures the energizing property of a wor-
thy cause or exciting vision provided by
the organizational leadership.
Virtual reality can be considered the pre-
ferred environment for the empowerment
process, since it is a special, sheltered set-
ting where patients can start to explore and
act without feeling threatened. In this sense
the virtual experience is an “empowering
environment” that therapy provides for pa-
tients. As noted by Botella [65], nothing
the patients fear can “really” happen to
them in VR. With such assurance, they can
freely explore, experiment, feel, live, and
experience feelings and/or thoughts. VR
thus becomes a very useful intermediate
step between the therapist’s office and the
real world.
Even if the clinical rationale behind the
use of VR is now clear, much of this re-
search growth, however, has been in the
form of feasibility studies and pilot trials.
As a result there is still limited convincing
evidence coming from controlled studies
(see Table 2), of the clinical advantages of
this approach. Up to now the clinical effec-
tiveness of VR was verified in the treat-
ment of these six psychological disorders:
acrophobia [66-68], spider phobia [69], pan-
ic disorders with agoraphobia [70], body
image disturbances [71], binge eating disor-
ders [72, 73] (see Fig. 2), and fear of flying
[74-78].
In the cognitive rehabilitation area the
situation is even worse. Even if different
case studies and review papers suggest the
use of VR in this area [12, 15, 79-85] there
are no controlled clinical trials to support
this position. A better situation can be
found in the assessment of cognitive func-
tions in persons with acquired brain inju-
ries. In this area VR assessment tools are ef-
fective and characterized by good psycho-
metric properties [86-90]. A typical exam-
ple of these applications is ARCANA. Us-
ing a standard tool (Wisconsin Card Sort-
ing Test – WCST) of neuropsychological
assessment as a model, Pugnetti and col-
leagues have created ARCANA: a virtual
building in which the patient has to use en-
vironmental clues in the selection of appro-
priate choices (doorways) to navigate
Table 1 VR hardware
Fig. 2
The Virtual Reality for Eat-
ing Disorders Modification -
VREDIM (Istituto Auxologico
Italiano I.R.C.C.S., Milan,
Italy)
Applications of Virtual Environments in Medicine
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Methods Inf Med 5/2003
through the building. The doorway choices
vary according to the categories of shape,
color, and number of portholes.The patient
is also required to refer to the previous
doorway for clues to appropriately make
his/her next choice.After the choice criteria
are changed, the patient must shift the cog-
nitive set, analyze clues, and devise a new
choice strategy. The parameters of this
system are fully adjustable so that training
applications can follow initial standardized
assessments.
4. VR Hardware and Software
For many years one of the main obstacles
to the development of VR applications was
the price of the equipment: a typical VR
system required a costly fridge-size Silicon
Graphic workstation in the range of
250,000 US$ and up. Even if high-end ap-
plications still require powerful worksta-
tions such as SGI Onyx or Octane (see
Table 1), during the last two years about
65% of the VR applications for health care
were developed for being used on PC plat-
forms.
The significant advances in PC hard-
ware that have been made over the last five
years, are transforming PC-based VR into
a reality. The cost of a basic desktop VR
system has gone down by many thousand
dollars since that time, and the functionality
has improved dramatically in terms of
graphics processing power. A simple im-
mersive VR system now may cost less than
6000 US$ (see Table 1).
The availability of powerful PC engines
based on such computing work-horses as
Intel’s Xeon and IBM G4/G5 processors,
and the emergence of reasonably priced,
Direct 3D and OpenGL-based 3D acceler-
ator cards allow high-end PCs to process
and display interactive 3D simulations in
real time.
While a standard Celeron/Duron pro-
cessor with as little as 128 Mbyte of RAM
can provide sufficient processing power for
a simple VR simulation, a fast Pentium
IV/Athlon XP-based PC (2.5 Ghz or faster)
with 256 Mbyte of RAM, can transport
users to a convincing virtual environment,
Table 2 Controlled trials with more than 10 patients/users included in Medline/PsycInfo (all fields query, accessed June 9,
2003)
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while a dual Xeon configuration (2.7 Ghz
or faster) with 1 Gbyte of RAM, OpenGL
acceleration and 256 Mbyte of VRAM run-
ning Windows XP Pro rivals the horse-
power of a mid-level graphics workstation.
The graphics card landscape, too, is
evolving quickly. In particular, two ad-
vancements are interesting for VR users:
the inclusion of a VGA-to-TV converter
and tuner, the Accelerated Graphics Port
(AGP) and the new faster 3D chips (Ge-
ForceFX 5900 Ultra, Radeon 9800 Pro)
with 128 Mbyte or more of dedicated video
Ram (VRam).
●
Accelerated Graphics Port (AGP): The
accelerated graphics port is a high-
speed, point-to-point connection be-
tween the system chip set and the graph-
ics chip. AGP provides a high-speed
pipeline between the graphics accelera-
tor and the PC’s system memory: using
an AGP connection, a graphics chip is
able to access system memory directly
through the system chip set at memory-
bus speeds, reducing latency and sub-
stantially increasing performance versus
standard PCI-memory transfers. The
graphics card gains access to system
RAM to store and execute texture bit-
maps, which allows more detailed tex-
tures of unlimited size while speeding
3D rendering. When textures are large,
AGP can make the difference between a
smooth or choppy frame rates in 3D
rendering.
●
Faster 3D cards: In VR, performance is
critical. VEs gave mainstream 3D accel-
eration its start, and developers have
been adding a sense of realistic depth to
their creations for years. However, the
addition of a z-axis in rendering, as op-
posed to simply drawing on an x, y-coor-
dinate plane, requires more sophisticat-
ed horsepower. In addition, VR applica-
tions contain more complex objects and
complex textures: bitmap renderings of
detailed surfaces (bricks, sand, or trans-
parent water) that heighten realism. To
exploit this potential a fast graphics card
with a lot of video Ram is a must. Happi-
ly, the new chip sets (GeForceFX 5900
Ultra and Radeon 9800 Pro) included in
consumer graphics cards have 16 times
more video Ram and 5 times more 3D
acceleration than the first generation of
chips (GeForce and Radeon VE) for a
price tag of less than 500 US$. Also,
professional graphics cards received a
significant speed bump. New Open GL
cards such as the Quadro 4 900XGL or
the FireGLX1 offer graphics power that
rival the one provided by Unix graphic
workstations.
●
VGA-to-TV converter: One welcome
feature of the new graphics cards is the
inclusion of a VGA-to-TV (NTSC or
PAL) converter and TV tuner right on
the card. This feature lets you display
computer data on a standard television
without the need for an external scan
converter (usually 100 US$ or more).
Business users can then give PC-based
presentations with TVs as large-screen
monitors, and home users can play com-
puter games on their TV sets. However
this feature is also useful for VR users:
thanks to the converter it is possible to
use – without any extra hardware – the
new low-cost DVD oriented head-
mounted displays from Olympus (Eye-
Trek, 600 US$) or Sony (Glasstron
PLM-A35, 500 US$).
On the software side, an interesting low
cost solution is the use of 3D engines in-
cluded in commercial 3D games for devel-
oping simple virtual environments. Many
3D games (50 US$ each), such as Quake or
Unreal, include level editors that allow the
user to customize the environments and the
avatars. Moreover, Discreet has released
free software, gmax™, that allows a profes-
sional customization of 3D games. Intend-
ed to be a fully capable 3D level editing,
modeling, animation, and texture-mapping
tool, gmax ships with a full suite of profes-
sional 3D content and animation features.
Discreet approved game developers can
publish gmax “game packs”, which custom-
ize the downloadable version of gmax
into a fully featured level editor for sup-
ported game titles. Using this software, it is
possible to edit and create 3D environ-
ments, materials, 3D objects, weapons, im-
ages and lights.
Obviously, level editing does not allow
full control of the environment. In particu-
lar, the user interaction with the 3D objects
is usually very limited. To overcome this
limitation, now there are different VR de-
velopment toolkits available for PCs, rang-
ing from high-end authoring toolkits that
require significant programming experi-
ence to simple “hobbyist” packages. De-
spite the differences in the types of virtual
worlds these products can deliver, the vari-
ous tools are based on the same VR-devel-
opment model: they allow users to create or
import 3D objects, to apply behavioral at-
tributes such as weight and gravity to the
objects, and to program the objects to re-
spond to the user via visual and/or audio
events. Ranging in prices from free (http://
www.alice.org) to 5000 US$ (Virtools Dev
2.5 or Sense 8 WorldUp R5), the toolkits
are the most functional of the available VR
software options. While some of them rely
exclusively on C or C++ programming to
build a virtual world, others offer simpler
point-and-click operations to develop a
simulation. Using VR toolkits, it is also pos-
sible to bring in files from a wide array of
software packages, such as Wavefront, 3D
Studio, EDS Unigraphics, Pro Engineer,
and Intergraph EMS, and they can also im-
port VRML and Multigen databases as well
as animation scripts and sounds.
5. Challenges and Open Issues
5.1 Technical Challenges
Even if the significant advances in comput-
er and graphic technology drastically im-
proved the characteristics of a typical VE,
VR is still limited by the maturity of the
systems available. Even today, no off-the-
shelf solutions are available. So, the set up
of a VR system usually requires a lot of pa-
tience for dealing with conflicting hardware
or lacking drivers. Nearly every VR system
requires a dedicated staff or at least com-
puter technician to keep the system run-
ning smoothly. Moreover, much VR tech-
nology is still uncomfortable or unpleasant
to use. In particular here are listed some
current VR technology limitations for users
[91]:
●
virtual acoustic displays that require a
great deal of computational resources in
Applications of Virtual Environments in Medicine
531
Methods Inf Med 5/2003
order to simulate a small number of
sources;
●
force and tactile displays, still in their in-
fancies, with limited functionality;
●
image generators that can’t provide
low-latency rendering of head tracked
complex scenes, requiring severe trade-
offs between performance and scene
quality;
●
position trackers with small working
volumes, inadequate robustness, and
problems of latency and poor registra-
tion.
●
HMDs with limited field of view, and en-
cumbering form factor.
As we have seen, a typical area for VR ap-
plications is surgery. However, there have
been few developments in the area of tac-
tile feedback.The ability to feel tissue is im-
portant. Procedures that require palpita-
tion, such as artery localization and tumor
detection, are extremely difficult when the
only form of haptic exploration is in the
form of forces transmitted through long,
clumsy instruments. As noted by Moline
[92], “The ability to remotely sense small
scale shape information and feel forces that
mesh with natural hand motions would
greatly improve the performance of mini-
mally invasive surgery and bring a greater
sense of realism to virtual trainers” (p. 21).
5.2 Safety Issues
The introduction of patients and clinicians
to VEs raises particular safety and ethical
issues [45]. In fact, despite developments in
VR technology, some users still experience
health and safety problems associated with
VR use [93]. The key concern from the
literature is VR-induced sickness, which
could lead to problems [94] including:
●
symptoms of motion sickness;
●
strain on the ocular system;
●
degraded limb and postural control;
●
reduced sense of presence;
●
the development of responses inappro-
priate for the real world, which might
lead to negative training.
The improved quality of the VR systems is
drastically reducing the occurrence of sim-
ulation sickness. For instance, a recent re-
view of clinical applications of VR reported
instances of simulation sickness are few
and nearly all are transient and minor [6].
In general, for a large proportion of VR
users these effects are mild and subside
quickly [93].
Nonetheless, patients exposed to virtual
reality environments may have disabilities
that increase their susceptibility to side ef-
fects. Precautions should be taken to ensure
the safety and well being of patients, includ-
ing established protocols for monitoring
and controlling exposure to virtual reality
environments.
Strategies are needed to detect any ad-
verse effects of exposure, some of which
may be difficult to anticipate, at an early
stage. According to Lewis and Griffin [94] ex-
posure management protocols for patients
in virtual environments should include:
●
Screening procedures to detect individ-
uals who may present particular risks.
●
Procedures for managing patient expo-
sure to VR applications to ensure rapid
adaptation with minimum symptoms.
●
Procedures for monitoring unexpected
side effects and for ensuring that the
system meets its design objectives.
Finally, the effect of VEs on cognition is not
fully understood. In a recent report, the US
National Advisory Mental Health Council
[95] suggested that “Research is needed to
understand both the positive and the nega-
tive effects [of VEs]… on children’s and
adult’s perceptual and cognitive skills”.
Such research will require the merging of
knowledge from a variety of disciplines in-
cluding (but not limited to) neuropsycholo-
gy, neuroimaging, educational theory and
technology, human factors, medicine, and
computer science.
5.3 Research and Clinical Issues
In the last five years there has been a steady
growth in the use of virtual reality in health
care due to the advances in information
technology and to the decline in costs [4].
As we have seen, using the “virtual reality”
keyword we can find 951 papers listed in
MEDLINE and 708 in PSYCINFO (all
fields query, accessed June 9, 2003). Much
of this growth, however, has been in the
form of feasibility studies and pilot trials.
The “best” evidence in evaluating the ef-
ficacy of a therapy/approach is the results
of randomized, controlled clinical trials.
However, if we check the available litera-
ture we can find only seventeen controlled
trials (see Table 2).
Three tested the training possibilities of-
fered by VR: in surgical training and in
teaching physical diagnosis skills. Twelve
verified the effectiveness of VR in the
treatment of four psychological disorders:
acrophobia, body image disturbances,
binge eating disorders and fear of flying.
The final study analyzed the use of VR in
the treatment of adult burn pain.
Why there are so few controlled trials in
VR research? The possible answers are
three.
First, the lack of standardization in VR
devices and software. To date, very few of
the various VR systems available are inter-
operable. This makes difficult their use in
contexts other than those in which they
were developed.
Second, the lack of standardized proto-
cols that can be shared by the community
of researchers. If we check the two clinical
databases, we can find only four published
clinical protocols: for the treatment of eat-
ing disorders [96], fear of flying [97], fear of
public speaking [98] and panic disorders
[99].
Finally, the costs required for the set-up
trials. As we have just seen, the lack of
interoperable systems added to the lack of
clinical protocols force most researchers to
spend a lot of time and money in designing
and developing their own VR application:
many of them can be considered “one-off”
creations tied to a proprietary hardware
and software, which have been tuned by a
process of trial and error. According to the
European funded project VEPSY Updated
[100], the cost required for designing a clin-
ical VR application from scratch and test-
ing it on clinical patients using controlled
trials may range between 150,000 and
200,000 US$. As noted by a recent report
prepared by the US National Research
Council [101],“the government support has
been the single most important source of
Riva
532
Methods Inf Med 5/2003
sustained funding for innovative research
in both computer graphics and VR. Begin-
ning in the 1960s with its investments in
computer modeling, flight simulators, and
visualization techniques, and continuing
through current developments in virtual
worlds, the federal government has made
significant investments in military, civilian,
and university research that laid the
groundwork for one of today’s most dy-
namic technologies. The commercial pay-
offs have included numerous companies
formed around federally funded research
in graphics and VR” (p. 227). In Europe the
most important source of funding for
health care VR applications was the Euro-
pean Commission through its Information
Society Technology programme. However,
in the last five years the funds for VR re-
search coming from the European Com-
mission has been between one-third and
one-fifth of the total amount distributed by
the US government.
6. Conclusions
In general, the review of current applica-
tions shows that VR can be considered a
useful tool for diagnosis, therapy, education
and training. However, several barriers still
remain. The PC-based systems, while inex-
pensive and easy-to-use, still suffer from a
lack of flexibility and capabilities necessary
to individualize environments for each pa-
tient [85]. On the other hand, in most cir-
cumstances the clinical skills of the thera-
pist remain the most important factor in the
successful use of VR systems. It is clear that
building new and additional virtual envi-
ronments is important so therapists will
continue to investigate applying these tools
in their day-to-day clinical practice [6]. Fur-
ther, many of the actual VR applications
are in the clinical investigation or laborato-
ry stage, as clearly showed by the lack of
controlled trials.
Significant efforts are still required to
move VR into commercial success and
therefore routine clinical use. Possible fu-
ture scenarios will involve multi-discipli-
nary teams of engineers, computer pro-
grammers, and therapists working in con-
cert to treat specific clinical problems.
Finally, communication networks have the
potential to transform VEs into shared
worlds in which individuals, objects, and
processes interact without regard to their
location. In the future, such networks will
probably merge VR and telemedicine ap-
plications allowing us to use VE for such
purposes as distance learning, distributed
training, and e-therapy.
It is hoped that by bringing together this
community of experts, further stimulation
of interest from granting agencies will be
accelerated. Information on advances in
VR technology must be made available to
the health care community in a format that
is easy-to-understand and invites participa-
tion [102]. Future potential applications of
VR are really only limited by the imagina-
tions of talented individuals.
Acknowledgments
The present work was supported by the Commis-
sion of the European Communities (CEC), in
particular by the IST programme (Project
VEPSY UPDATED, IST-2000-25323, http://
www.cybertherapy.info, http://www.e-therapy.
info; Project EMMA, IST-2001-39192).
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Correspondence to:
Prof. Giuseppe Riva, Ph.D.
Dipartimento di Psicologia
Università Cattolica del Sacro Cuore
Largo Gemelli 1
20123, Milan, Italy
E-mail: auxo.psylab@auxologico.it
Web site: http://www.atnplab.com
