Virtual Reality for the Palliative Care of Cancer

Transcription

1 Virtual Reality for the Palliative Care of Cancer Hiroshi Oyama Medical Virtual Reality Development Lab National Cancer Center Hospital 5-1-1, Tsukiji, Chuo-ku, 104 Tokyo, Japan Abstract. 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. 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

2 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 treating psychological problems (neurosis, etc.) through the presentation of a pleasant virtual space using VR technology [1]. 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. 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) Psycho-oncological 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. 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. 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. 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

3 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 patients. These organs have texture-mapping and typical cancer images. Auditory information 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 iso-surfacing are made possible by highperformance image-processing with parallel AVS (Advanced Visualization 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 ( Research concerning the processing of shape data for medical treatment over a network is now underway using VRML. 6. Psycho-oncological VR therapy project: This project is described in the section on the Bedside Wellness System (paragraph 6). 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 frames/sec for monocular viewing and 6-7 frames/sec for binocularstereo 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 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 imageprocessing system. 3D texture-mapping and iso-surfacing 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

4 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 1). HMD SP2 40 nodes Onyx Boom3c 100inches dispaly Onyx Position Senser CT, MR Medical Image Data Base Indigo RS6000 3D mouse Stylus PHANToM Figure 1. System configuration at the National Cancer Center Medical VR Laboratory 4. Application of VR to palliative medicine at the National 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 [2]. 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.

5 4.2 Concepts of our VR research on palliative medicine 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. 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 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. 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. 5. Psycho-oncological Treatment System 5.1 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. 5.2 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-

6 wide screen projected 2D movie, (2) 100-inch-wide screen projected 3D movie with shutter 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-millionpixel 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-millionpixel HMD and 2D movie, (14) 51-million-pixel HMD and 3D movie, (15) 51-millionpixel 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). (1)-(4) (5)-(6)(9)(10)(15) (7)(8)(13)(14) 100-inch-wide screen Video player 2D movie 3D movie PC-based VR system Virtual Cancer Hospital 2D application 3D application (7)-(12) (13)-(18) (11)(12)(17)(18) Two Onyx computers interactive 2D application Interactive 3D application Figure 2. VR tools used in the study of VR psycho-oncological 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

7 and a flight simulator that are operated by using a 3D mouse or a stylus. 5.3 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 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. 5.4 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. 6. Bedside Wellness System 6.1 Concepts The National Cancer Center Hospital and Mitsubishi Electric Corporation Advanced Technology R&D Center have been conducting a 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. 6.2 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 a 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 rate, 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].

8 6.3 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 birds, a brook and trees. A wide field-vision of 100 degrees are possible using three liquid-crystal screens. 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 while the patient was experiencing walking in the forest to evaluate the effect of this treatment. 6.4 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. Reference [1] Oyama, H., et al. VR medical support system for cancer patients. Cancer edutainment VR theater (CEVRT) and psycho-oncological VR therapy (POVRT). Interactive Technology and Healthcare, : Edited by R. M. Satava et al., IOS Press and Ohmsha, [2] Cancer Pain Relief and Palliative Care. Technical Report Series 804. Geneva: World Health Organization, [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 , [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.), p , 1996.