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GIUSEPPE RIVA, BRENDA K. WIEDERHOLD, ENRICO MOLINARI (Eds.)
Virtual Environments in Clinical Psychology and Neuroscience
1998 © Ios Press: Amsterdam, Netherlands.
VIRTUAL REALITY
FOR PALLIATIVE MEDICINE
HIROSHI OYAMA
Medical Virtual Reality Development Lab
National Cancer Center Hospital
5-1-1, Tsukiji, Chuo-ku, 104 Tokyo, Japan
Abstract. The technology of virtual reality (VR) offers several advantages in the
field of medicine because it enables us to practice medical procedures repeatedly,
and can provide a variety of experiences by using virtual organs in different
patients. It also aids in learning about a clinical procedure and facilitates objective
evaluation by a supervisor.
In the field of clinical oncology, a virtual environment can be useful for simulating
surgery, diagnosing cancer invasion, obtaining informed consent or enhancing
patient education, and for clinical communication using network-based VR. This
technology can also be used to improve a patientÕs living conditions and to treat the
psychological problems and/or stress of cancer patients. In the present chapter
advanced VR research for palliative medicine at the National Cancer Center
Hospital Japan is described and discussed.
1. Introduction
Since the VR technology presents information to human sensory systems, it is very
closely related to medicine itself. For example, an HMD (Head-Mounted Display) can
project a virtual image to the human visual system. Thus, this technology can be used to
treat weak vision and neurosis such as ICU (Intensive Care Unit) syndrome. Humans
mature and gain experience by receiving stimulation from their environment. It is possible
to gain experience in virtual space in addition to real space by using VR technology, such as
in surgical simulation or training. Moreover, VR technology is likely to applied to the field
of psycho-oncology as well as to desensitization treatment for various phobias.
VR technology may also be used to present difficult medical information. In the 21th
century, the technology used to present information regarding medical treatment will be
very important for obtaining informed consent, for patient education, and for enhancing the
education of medical students. Another application of virtual space is on a network, since
VR technology make it easy to exchange information.
2. Outline of MedVR projects at the National Cancer Center Hospital
2.1 Aim of our VR projects
At the National Cancer Center Japan, medical virtual reality (MedVR) projects were
begun in 1993 as supercomputer projects approved by the Ministry of Health and Welfare.
The aim of our research project is to advance cancer treatment and support patients who are
fighting against cancer using VR technology.
2.2 Hypothesis
We assume that humans have interacting mental and physical homeostasis. Cancer
erodes mental stability and physical homeostasis due to tissue destruction and cachexia. A
vicious circle develops since if mental homeostasis worsens, physical homeostasis worsens,
and vice versa. It is thought that VR technology can be used to regulate both homeostasis.
Mental homeostasis may be recovered by reducing a cancer patientÕs stress and/or by
GIUSEPPE RIVA, BRENDA K. WIEDERHOLD, ENRICO MOLINARI (Eds.)
Virtual Environments in Clinical Psychology and Neuroscience
1998 © Ios Press: Amsterdam, Netherlands.
treating psychological problems (neurosis, etc.) through the presentation of a pleasant
virtual space using VR technology.
Figure 1. Our basic hypothesis for researching VR technology
On the other hand, to restore physical homeostasis, the minimum invasive surgery is very
important for reducing physical damage to the patient and for removing the cancer itself and
tissue and/or organs destroyed by the cancer (Figure 1).
2.3 Nature of MedVR projects
Six virtual reality projects based on the above-mentioned hypothesis are currently
underway: (1) Surgical simulation support project , (2) Psychooncological therapy project,
(3) Medical education support project, (4) Medical image diagnosis support project, (5)
Informed consent support project (Cancer information VR theater), and (6) Virtual medical
communication project (medical VRML):
(1) Surgical simulation support project:
When a surgical procedure is planned, the exact location of the tumor and knowledge of
the surrounding tissue are very important for the surgeon. Especially in neurosurgery, an
additional skin incision and craniotomy are very difficult to perform during the operation.
Thus a neurosurgeon must have a very precise understanding of the situation before surgery.
The purpose of the present application is to estimate the optimal position of the patient's
head to reach the brain tumor and to decide upon the location of the skin incision and
craniotomy for minimal invasive surgery (Photograph 1).
(2) Medical education support project:
Many young doctors and nurses visit the National Cancer Center Hospital every year for
training in clinical. In this project, we are developing a training system using a virtual
environment on the internet.
(3) Medical image diagnosis support project:
We have developed technologies for medical virtual reality and have applied these
technologies to present medical images. Real-time volume rendering is useful for diagnosis
or pre-surgical simulation. We customized real-time volume-rendering volren-6 software
(SGI) on an Onyx computer. We can observe 3D cancer images based on CT (Computed
Tomography) or MRI (Magnetic Resonance Imaging) data using two real-time volume-
rendering methods.
GIUSEPPE RIVA, BRENDA K. WIEDERHOLD, ENRICO MOLINARI (Eds.)
Virtual Environments in Clinical Psychology and Neuroscience
1998 © Ios Press: Amsterdam, Netherlands.
Photograph 1.Training with the surgical simulation system
We evaluated the benefits of real-time volume rendering for medical use, and
concluded that real-time volume rendering can help a doctor recognize physical
structures because it can describe the relationships between vessels and cancers more
clearly than surface rendering (Figure 2).
Figure 2. Brain tumor shown by real-time volume rendering
(4) Informed consent support project (Cancer information VR theater):
Patients and their families have a right to know about their cancer. However, it is often
difficult for a doctor to provide such information. VR technology can be used to achieve a
very realistic presentation. In addition, interns and new nurses must be trained to perform
various tasks in clinical fields. Training of these beginners in virtual space can be reduce the
initial risk for patients. The shape data for these organs were initially produced using
Viewpoints data, but are now produced using CT or MR data from cancer pat ients. These
organs have texture-m apping and t ypical cancer images. Auditory infor mation is recorded by an
Indigo II sound system.
Patients can hear information about these cancer and sound effects whenever they want
in virtual space. High-performance image-processing is available for image data in a
database in DICOM 3 format.
When the patient's own image is presented, texture mapping and isosurfacing are made
possible by high-performance image-processing with parallel AVS (Advanced Visualization
GIUSEPPE RIVA, BRENDA K. WIEDERHOLD, ENRICO MOLINARI (Eds.)
Virtual Environments in Clinical Psychology and Neuroscience
1998 © Ios Press: Amsterdam, Netherlands.
Software) running on a massive parallel supercomputer (SP2) and a onyx computer. The
image data come from a huge image database which consists of clinical MR- and CT- slice
images in DICOM3 format. The organs image are extracted by CliPPS software.
Many sounds are edited with an Indigo II sound server and are created with a VR-DECK
(Virtual Reality Distributed Environment and Construction Kit: IBM ) module. The purpose
of this database is to manage 3D image data and to construct optimal human or organ
images for use in virtual space.
(5) Medical VRML (Virtual Reality Modeling Language) project:
It is thought that three-dimensional shape data will be used on the internet in the near
future. We think that networked VR offers two main benefits. First, a patient can be helped
to understand special medical information as easily as possible. Second, networked VR can
be used to share diagnosis and treatment information among doctors and/or nurses. A
Virtual Cancer Hospital was developed on a PC-based system using VRT (Superscape), and
virtual cancer models are now available to the public on the internet
(http://medvr.res.ncc.go.jp). Research concerning the processing of shape data for medical
treatment over a network is now underway using VRML.
Figure 3. Organ Images: The lung and major bronchus, stomach, liver and, colon and rectum.
(6) Psychooncological VR therapy project:
This project is described in the section on the Bedside Wellness System (see also Oshuga
and Oyama in this book).
3. System configuration at the National Cancer Center Medical VR Laboratory
The hardware consists of three high-performance graphic workstations (two Onyx/RE2
and one Indigo-II Extreme) and a video-editing system. The software used to develop the
VR environment is structured so that computations are distributed on the three workstations.
Using the two Onyx computers to generate the image, the simulation system achieves
frame-rates of 11-12 frames/sec for monocular viewing and 6-7 frames/sec for binocular-
stereo viewing of a scene with 15K visible triangles. The VR database is constructed for
each patient after editing polygon images of the cancer and related organs from CT or MR
images. The simulated environment for a patient is referred to as a virtual reality
GIUSEPPE RIVA, BRENDA K. WIEDERHOLD, ENRICO MOLINARI (Eds.)
Virtual Environments in Clinical Psychology and Neuroscience
1998 © Ios Press: Amsterdam, Netherlands.
environment file (vef). The surgeon can select the individual vef for a patient from a menu
window. The 3D images are stored on VHS or 8-mm videotape.
We designed the infrastructure for medical virtual reality using a data-flow diagram. We
analyzed all of the processes which use medical modalities to produce medical images, an
image segmentation process, an image storage process and its data format, an image transfer
process and an image format exchange process. We use a high-performance image-
processing system. 3D texture-mapping and isosurfacing are performed using parallel AVS
(Advanced Visualization Software) on a massive parallel supercomputer (SP2) and an Onyx
computer. The image data are stored in a huge image database which consists of clinical
MR- and CT-slice images in DICOM 3 format. The volume of our 3D texture is limited to
under 128X128X64. We have a high-performance network which consists of an FDDI
switch and a HIPPI switch. It is very useful for CT or MR images to be quickly transported
to the VR database.
We mainly use Boom 3C for observation of the surgical simulation due to its high
resolution and pseudo-colonization. A Fastrak pointing device is used as a tool in virtual
space to represent surgical instruments such as a knife, bipolar coagulator, tweezers, air drill
and so on. High-performance image processing Image data are drawn from an image
database in which the data format is based on DICOM 3. 3D texture-mapping and
isosurfacing are achieved using parallel AVS (Advanced Visualization Software) on a
massive parallel supercomputer (SP2). The organ or cancer image data are extracted from
an image database composed of MR- and CT-slice images in DICOM 3 format using
CliPSS software.
The volume of the 3D texture is limited to 128X128X64 and the shape data are limited to
about 10,000 triangles. An FDDI switch and a HIPPI switch are used to transport the
enormous volume of image data from the image database to the high-performance
workstation. Background sounds are edited with an Indigo II sound-server to increase the
reality of the simulation. We also use a switching system to exchange an image in a 3D
color video system and a virtual view in the surgical simulation support system. The 3D
camera consists of right and left CDD cameras with a resolution of 410,000 pixels, and the
image can be enlarged six times. The cameras measure 65 x 25 x 130 mm, weigh
approximately 3.5 kg., and have an electrically-driven zoom lens (F 1.2 ~ 22). The system
presents virtual organs and cancers interactively using HMD devices. In addition, the
system allows interactive surgical procedures to be performed on a cancer model. The
cancer model is generated from CT or MR images using a 3D texture method. Using this
method, it is possible to visualize the internal structure of the organ as the simulated
resection takes place (Figure 4).
4. App licati on of VR t o pall iative medicine at the Nati onal Cancer Center Hospital
4.1 What is palliative medicine?
A useful definition of palliative medicine has been suggested by the World Health
Organization: The active total care of patients whose disease is not responsive to curative
treatment. Control of pain, other symptoms, and psychological, social and spiritual
problems, is paramount. The goal of palliative care is to achieve the best quality of life for
patients and their families. Many aspects of palliative care can be applied early in the course
of the illness in conjunction with anticancer treatment. Palliative medicine involves patient
care and the study of that care [1]. The standard approach in palliative medicine consists of
(1) recognition of a present psychological problem, (2) a definable goal, (3) a treatment
method for resolving the problem to reach the goal, agreed upon by the therapist and the
patient, and (4) the patient carrying out the agreed-upon treatment.
4.2 Work on palliative medicine at the National Cancer Center Hospital
The National Cancer Center was established in 1962. It has two affiliated hospitals and a
research institute supervised by the Ministry of Health and Welfare. The National Cancer
Center Hospital has 530 beds for cancer patients, and the National Cancer Center Hospital
East has 400 beds. The National Cancer Center Hospital consists of 12 divisions. The
hospital staff consists of 116 staff doctors, 18 pharmacists, 83 technicians, 379 nurses and
GIUSEPPE RIVA, BRENDA K. WIEDERHOLD, ENRICO MOLINARI (Eds.)
Virtual Environments in Clinical Psychology and Neuroscience
1998 © Ios Press: Amsterdam, Netherlands.
73 residents and chief residents. The basic policies of the hospital are 1) to make an early
diagnosis and treatment of cancer, 2) to improve the treatment results for presently
intractable cancers, 3) to achieve the best quality of life for cancer patients after definitive
therapy, and 4) to develop new procedures for primary cancer prevention.
SP2 40 nodes
Onyx
Onyx
Indigo
Boom3c
HMD
100inches
dispaly
Stylus
3D mouse
Position
Senser
PHANToM
CT, MR
Medical
Image
Data Base
RS6000
Figure 4. System configuration at the National Cancer Center Medical VR Laboratory
The patient support team was started in July 1994, and is staffed by nurses, oncologists,
pharmacists, nutritionists, and administrators, all of whom are volunteers. The aims of this
team are: (1) to provide patients, their families, and other members of the public with
appropriate and up-to-date cancer information; (2) to support and facilitate care services,
especially for terminally ill patients; and (3) to coordinate the activities of groups with
similar purposes. The Palliative Care Unit (PCU) was established at the campus of the East
Hospital to provide psychological and social support of patients with advanced cancer. This
unit has no religious affiliation because the hospital receives government support. The
psychological and physical support of dying patients is another important role of the PCU.
In 1993, the government approved the use of supercomputers at the National Cancer
Center Hospital. Our VR project is one of several projects which use supercomputers [2].
5. Concepts of our VR research on palliative medicine
5.1 Improvement of patient's living conditions and rehabilitation
Patients in the terminal stage of cancer complain of cancer pain (68%), appetite loss
(22%), abdominal discomfort (18%), general fatigue (17%), nausea and vomiting (11%),
cough and sputum (10%), sleep disturbance (7%), constipation (4%) and a dry mouth (4%).
The symptoms of pain, appetite loss, abdominal discomfort, general fatigue, nausea and
sleep disturbance are thought to be made worse by psychological stress or an unstable state.
We often find that terminally ill patients who cannot move want to visit their native country
or hometown. To realize such desires, we are researching ways to create virtual worlds.
5.2 Stress reduction by biofeedback therapy
Cancer patients also complain of an increase in insomnia and symptoms of nervous
disorders due to mental stress. In addition, many patients exhibit symptoms that are similar
to side-effects, but which are not directly related to the use of medications. This anticipatory
nausea and vomiting is due to long-term hospitalization. We use five treatment methods
(passive relaxation, active relaxation, biofeedback, systematic desensitization treatment, and
GIUSEPPE RIVA, BRENDA K. WIEDERHOLD, ENRICO MOLINARI (Eds.)
Virtual Environments in Clinical Psychology and Neuroscience
1998 © Ios Press: Amsterdam, Netherlands.
acknowledgment or attention conversion treatment) to treat such symptoms. We are trying
to use VR technology to help such patients relax. Biofeedback therapy is a technique in
which a patient tries to control physiological parameters, which are normally reflected in
electromyograms, skin temperature, blood pressure, heart beats, and brain waves, by
monitoring these parameters after they have been converted to easy to understand sounds,
lights, or computer graphics [3]. It is expected that the association of this approach with VR
technology will expand the opportunities in this area. We are developing a system by which
a cancer patient can observe his/her own physical parameters in virtual space.
5.3 Enhanced human communication and counseling supported by Kansei engineering
Humans can sense their environments by seeing, hearing, touching, and tasting. Kansei
engineering involves the study of such sensation by computer science. The study of Kansei
engineering started in Japan. As the first step in our Kansei research, we analyzed a cancer
patient's Kansei using VR technology in a virtual environment and sought to measure the
characteristic Kansei of a cancer patient to enhance doctor-patient and nurse-patient
communication and to promote the counseling of cancer patients (Figure 5).
Network
Graphic
data
VR_PC
Kansei
data
Kansei processing PC
,g,l,c
AD¥ìSáS’
Voice
ECG
EEG
Pupile diameter
VR
data
Figure 5. Concept of our Kansei research system
6. VR Psycho-oncological Treatment System
6.1 Concepts
The goal of this research is to improve the patient's living conditions. The technology of
virtual reality is emerging as a new method to stimulate cancer patients and their families.
Cancer patients sometimes require long-term hospitalization for treatment. Under long-term
hospitalization, patients want to maintain their relationships in society and sometimes
complain of neurosis-like symptoms. We propose that psychological treatment can help
cancer patients feel as though they are in another world.
6.2 Methods
We have tried to develop a VR system for presenting a virtual world to cancer patients
and have been researching the application of medical VR systems to treat the psychological
problems of patients with cancer. Systems which we have evaluated include (1) 100-inch-
wide screen projected 2D movie, (2) 100-inch-wide screen projected 3D movie with shutter
GIUSEPPE RIVA, BRENDA K. WIEDERHOLD, ENRICO MOLINARI (Eds.)
Virtual Environments in Clinical Psychology and Neuroscience
1998 © Ios Press: Amsterdam, Netherlands.
glasses, (3) 100-inch-wide screen projected interactive 2D application, operated by using a
mouse, (4) 100-inch-wide screen projected interactive 3D application with shutter glasses,
operated by using a 3D mouse or stylus, (5) PC monitor and PC-based interactive 2D
application, operated by using a mouse, (6) PC monitor and PC-based interactive 3D
application with shutter glasses, operated by using a 3D mouse or stylus, (7) 18-million-
pixel HMD and 2D movie, (8) 18-million-pixel HMD and 3D movie, (9) 18-million-pixel
HMD and PC-based interactive 2D application, (10) 18-million-pixel HMD and PC-based
interactive 3D application, (11) 18-million-pixel HMD and Onyx-based interactive 2D
application, (12) 18-million-pixel HMD and Onyx-based 3D application, (13) 51-million-
pixel HMD and 2D movie, (14) 51-million-pixel HMD and 3D movie, (15) 51-million-
pixel HMD and PC-based interactive 2D application, (16) application, (17) 51-million-pixel
HMD and Onyx-based interactive 2D application, and (18) 51-million-pixel HMD and
Onyx-based 3D application (Figure 6).
100-inch-wide screen
PC-based VR system
Virtual Cancer Hospital
2D application
3D application
(1)-(4) (5)-(6)(9)(10)(15)
Video player
2D movie
3D movie
Two Onyx computers
interactive 2D application
Interactive 3D application
(7)(8)(13)(14)
(11)(12)(17)(18)
(7)-(12) (13)-(18)
Figure 6. VR tools used in the study of VR psychooncological treatment
We use a commercially available 8-mm video camera to provide 2D image content.
Commercially available films are also used. The PC-based application Virtual Cancer
Hospital is made by Superscape. The purpose of this walk-thorough application is to
increase the patient's knowledge of cancer while they wander around a virtual cancer
hospital. The 3D applications run on two Onyx computers. We also use a driving simulator
and a flight simulator that are operated by using a 3D mouse or a stylus.
We use a commercially available 8-mm video camera to provide 2D image content.
Commercially available films are also used. The PC-based application Virtual Cancer
Hospital is made by Superscape. The purpose of this walk-thorough application is to
increase the patient's knowledge of cancer while they wander around a virtual cancer
hospital. The 3D applications run on two Onyx computers. We also use a driving simulator
and a flight simulator that are operated by using a 3D mouse or a stylus.
6.3 Results
With a 2D movie, patients noted that watching a movie on a 100-inch-wide screen
helped them to forget that they were in fact being hospitalized. Patients particularly liked
seeing movies that made them feel good, so that they would not feel uneasy about their
cancer while enjoying the movie. Although systems which used a 100-inch-wide screen
required a special room in the hospital, and patients faced the inconvenience of having to
move from their ward, this was in fact a benefit, since the change in environment
contributed to the feeling of escapism. Systems which included an HMD were preferred for
GIUSEPPE RIVA, BRENDA K. WIEDERHOLD, ENRICO MOLINARI (Eds.)
Virtual Environments in Clinical Psychology and Neuroscience
1998 © Ios Press: Amsterdam, Netherlands.
bedside use. However, several patients felt eye fatigue after watching a movie, while the
incidence of eye fatigue was lower with an interactive application. Younger patients readily
adapted to wearing the HMD, while older patients sometimes felt discomfort. The
interactive application was most popular when presented in a virtual environment. However,
with a poorly designed interactive virtual image and manipulation devices, a VR system
might make the patient feel nauseous.
6.4 Future work
We think that VR is an important technology that can be used to overcome various
problems in the medical field. Unfortunately, there are currently no established methods for
evaluating medical VR systems. Moreover, in the future it will be important to be able to
recognize problems with VR technology in terms of the subject's VR experience.
7. Bedside Wellness System
7.1 Concepts
The National Cancer Center Hospital and Mitsubishi Electric Corporation Advanced
Technology R&D Center have been conducting research aimed at supporting the care of the
minds and bodies of patients and the elderly in sickbeds. Cancer pain is a major source of
psychological stress. This psychological stress caused by cancer pain sometimes leads the
patient to experience sleep disturbance, to be anxious and fearful, and to feel depressed and
lonely. When cancer pain is alleviated with drugs, the patient may feel comfortable enough
to sleep well, rest, become quiet and enjoy the company of friends. Particularly in terminal
cases, it is very important for patients to improve their quality of life and to control cancer
pain and other uncomfortable symptoms. It is also important to enjoy a social and spiritual
life.
7.2 Basic study
In this study, physiological parameters such as autonomic responses and subjective
assessment were used to evaluate the effect of experience in a virtual environment. A
driving simulator and flying simulator were introduced to help the subjects relax and to
reduce pain which was induced by thermal stimuli as an external stressor. One of the ten
subjects felt nauseous, while another's heart rate decreased moderately. An increase in
respiration, elevation of the pain threshold and subjective positive emotion were also
observed during the experience. These results suggest that experience in a virtual
environment can help to reduce stress and allow a subject to relax [4].
7.3 System configuration
To provide for the mental care of patients who are subjected to long-term hospitalization,
we developed a system to simulate the experience of basking in a forest. This system used
interactive VR technology to provide mental stimulation and rehabilitation at the patient's
bedside. This system simulates the experience of basking in a forest by stimulating the
senses of sight, sound, touch and smell. To promote the feeling of movement, actual
photographs were taken synchronized with a walking pace. The presentation includes not
only reflections but also a fresh wind which carries the smell of the forest and the sounds of
small bir ds, a brook and tr ees. About 100 ref lections are possible usi ng thr ee liquid-cr ystal
scr eens. Walking is simulated not only to enhance the reality of the experience, but also to
promote early rehabilitation. Vital signs (electrocardiogram, blood pressure, and breathing)
were measured in real-time while the patient was experiencing walking in the forest to
evaluate the effect of this treatment.
7.4 Future work
In the future, we hope to use this system clinically to verify its usefulness. We are
considering expanding the system for use over a network, so that two or more people can
meet and chat while basking in a forest.
GIUSEPPE RIVA, BRENDA K. WIEDERHOLD, ENRICO MOLINARI (Eds.)
Virtual Environments in Clinical Psychology and Neuroscience
1998 © Ios Press: Amsterdam, Netherlands.
Photograph 2. The Bedside Wellness System
8. Conclusions
We have been developing a VR system to provide patients with emotional support and to
encourage them to assume an active life against cancer, since patients with an active
lifestyle survive longer than those with a passive lifestyle. A possible explanation for this
latter fact is that psychological stimulation may also activate the endocrine system and the
immune system. Both systems may be able to rapidly repair tissue damaged by cancer and
change the characteristics of the cancer itself. Although microelectrical analysis and
molecular and genetic analyses are rapidly solving the riddles of the relationship between
the brain and thought, we think that our VR research for palliative medicine may also play
an important role in this area with regard to the development of new tools for treatment and
support.
This notion is based on the hypothesis that the brain can reorganize itself to compensate
for irrationality or inappropriateness through pharmacological adaptation and/or anatomical
regeneration of synapses. Another reason why VR research in palliative medicine is useful
is that VR techniques represent not only an enhanced human-machine interface, but also an
enhanced human communication technology.
VR technology may also be used to help patients accept their disease. The mental state of
a patient in the terminal stage of cancer changes step by step from denial of cancer, hope for
a new treatment for cancer, suspicion of medical treatment, uneasiness regarding their
future life, irritation, depression, and acceptance or despair. We plan to develop a new type
of counseling system in medical cyberspace to provide mental care. It can also be used for
group therapy or humor therapy to reduce loneliness.
In summary, we conclude that VR technology can be applied to palliative medicine (1) to
support communication between the patient and others, (2) to provide psychological support
to treat neurosis and help to stabilize the patient's mental state, and (3) to actually treat
cancer.
GIUSEPPE RIVA, BRENDA K. WIEDERHOLD, ENRICO MOLINARI (Eds.)
Virtual Environments in Clinical Psychology and Neuroscience
1998 © Ios Press: Amsterdam, Netherlands.
References
[1] Cancer Pain Relief and Palliative Care. Technical Report Series 804. Geneva: World Health
Organization, 1990.
[2] Oyama, H., et al. VR medical support system for cancer patients. Cancer edutainment VR theater
(CEVRT) and psychooncological VR therapy (POVRT). Interactive Technology and Healthcare,
433-438: Edited by R. M. Satava et al., IOS Press and Ohmsha, 1995.
[3] Shwartz MS, Single-site versus Multisite and Single-modality versus Multimodality monitoring and
feedback, and the issue of microcomputer-based system. Guilford Pr, New York, pp 291-232, 1987.
[4] Kimura M., Ohsuga M., Okamura H. and Oyama H.. A Basic Study For Human Stress Reduction by
Virtual Reality System. International Conference on Virtual Systems and Multimedia (Proc.), p525-
529, 1996.
