Department of Medical Information Science, Osaka University Hospital 2-25, Yamada-Oka, Suita 565 Japan
The management of selecting input resources and overlaying the pictures was so complicated that a director-assisting system (Mitsubishi Electric) was developed on a Macintosh computer system. The system was able to control matrix switches, NTSC cameras and other resources. A staff could easily register some screen patterns in advance, and image patterns were selected by a function key on a site. Several staffs were needed to handle the experiment at first, but recent experiment required a few operators at both sites.
Data acquisition and print out: The film scanner (Leafscan45, Leaf Systems) and the digital still camera (Leaf Digital Studio Camera, Leaf Systems) are connected to the personal computer (MAC 8100/80). The film digitizer (LD-4500, Konica) and the color printer (Fujix Pictograph 3000, Fuji Photo) are linked to the workstation (Sun SS20). The film digitizer and the digital camera which allow flexible input have spatial resolution of more than 3000 pixels x 2000 lines at more than 12 bits depth. After the input image data are processed on the computers, connected to the input device, they are then transferred to the SHD image server via LAN.
Data processing and storage: The image server (SHD-1000, Mitsubishi Electric) and an image database are installed. The server is able to contain 256 SHD images on local RAM that corresponds to 3 Gigabytes data volume. The SHD image data for each RGB signal channel are transmitted through 8 Gbps display bus, and converted to analog output with the rate of 357 mega-samples per second. Frame rate is achieved as progressive 60 frames per second. A video board for simple television meeting can also be connected to this server to digitize NTSC signals. The video signals input into the video board are used as a device to input non SHD images with low resolution.
Display: The SHD monitor (DDM2801, SONY) is used for the display which is able to demonstrate 2048 pixels x 2048 lines and temporal resolution is up to 60 frames per sec with non-interlace RGB 8 bits image.
Communication: The SHD system provides an environment for multipoint SHD conference. The three sets of the local system are connected via B-ISDN. The pictures in the system are transferred to another one beforehand and can be controlled from remote points (Figure 3). An electronic television conversation system is also installed in the control unit of the workstation to communicate among the sites.
In constructing an image filing system which archives a variety of medical images, a cardiovascular disease case was selected as an example. Since the patient underwent twice PTCA (percutaneous transluminal coronary angioplasty) because of restenosis of the artery, her clinical history can be divided into 4 phases (before and after the first and the second PTCA). In the filing system, we stored the pictures of case summary, electronic cardiogram, chest roentgenogram (CX), ultrasonic cardiogram (movie)(US), myocardial scintigram (MS), coronary angiogram (movie) (CA) and left ventriculogram (movie)(LV) in each phase. The total number of stored pictures was 243 frames. In order to improve retrieval operability, a GUI (Graphic User Interface) displaying a matrix was developed. The vertical axis indicates the types of medical modalities and the horizontal axis, the time course. By clicking a button on the matrix, users can retrieve and instantly display the chosen modality image from the SHD image frame memory.
As for the operability, all images were stored in the frame memory and waiting time for the image to be displayed was extremely short. The GUI matrix which presented seven types of modality-specific images in four phases was good to help the user operate several images and to select the desired image easily.
As for resolution, CX, CA, LV received high evaluation and US and MS received low evaluation. There may be a problem in the images' input methods for US and MS. And the fact that images of CX, CA, LV that have high resolution in origin were evaluated highly indicated that display of these images was feasible by the SHD format. The above suggested that the SHD image format would be sufficient in terms of quality at least for the types of images handled in this experiment. The system was also capable of displaying animated images without losing its high quality.
Doctors also shared opinions regarding the system's effectiveness in the medical practice. Physicians' need to compare two or more images of different phases on the same screen surfaces was fulfilled in the experiment. Out of US and LV and other images which are generally poor in quality, two or more selected images with different phases were simultaneously displayed on one screen. Its convenience in observation was graded highly for effectiveness in a patient care. Use in education system and study groups were evaluated as "can be used" and use as clinical research database was evaluated as "can mostly be used."
In teleconference experiments between Osaka University and Kyoto University via B-ISDN, it took 2 hours to transfer all the pictures (about 3GB) beforehand. Owing to the prefetch procedure, we could select the picture quickly using user friendly interface tool which also controlled the remote system simultaneously. The system also showed pointer function not only in static picture but also in movie. When we stopped the movie, we could see the same frame in both side. The conference finished without any trouble as though it held in the same room. The success demonstrated that super high definition system and B-ISDN based system is enough specification to deal the high quality-oriented telemedicine.
In a case of the Osaka university hospital, the studio functions as the interface between the CS ground station (Mitsubishi Electric, Tokyo) and halls where AV input and output resources are allocated. The surgical operation AV control center has an HTDV camera (Ikegami, Tokyo) for sending live scene of a surgical operation. The dynamic images are sent to the studio via optical fiber lines. The lecture hall and the conference hall are connected with optical fibers for image and voice data transfer, and ether net for communicating control data. The control processor (Hitachi, Tokyo) is linked to matrix switchers (Mitsubishi Electric, Tokyo) of HDTV, NTSC image and voice data. Due to the control network, an operator in a hall is able to receive the information from a distant teaching site and choose a necessary media with a "one man operation" method.
To make telemedicine in practice, the quality of image, response time of communication ,cost and doctor's attitude are major problems. In order to solve the problem within boundary condition, commercially available HDTV systems have been chosen at first and SHD is further tried with communication technology of B-ISDN or CS. From the standpoint of the information processing and communication, the quality is the most high hurdle to clear. Conventional X-ray film has a 2K x 2K x 12 bit (6MB) and if the still image is converted to color dynamic image (30 frames per sec), the data quantity is calculated 540 MB per sec. In our experiments, more than 1K x 1K of spatial resolution and 30 to 60 frames per sec of temporal resolution were targeted and combination of multimedia and high speed communication tool of B-ISDN and CS were applied. Although qualitative evaluation has not been made, medical staffs were accepted our design of high quality oriented telemedicine.
As to the cost, high quality does not enjoy the scale merit of lowering cost in the present. The minimum initial investment will be estimated as follows: input device such as a HDTV camera, a video recorder and so on, A$0.5M, display such as a HDTV rear projector, a CRT monitor, A$0.3M, interface device such as a matrix switcher, A$0.2M. If a SHD system will be introduced, the cost will be calculated as A$1.5M and as for CS ground station it will cost about A$1.2M. Running cost for B-ISDN will be about two thousand times more than conventional telephone line use and for rental fee of a transponder of a CS is A$3K per hour. It will be natural to expect that the total cost will be decreased sharply if HDTV, SHD systems are commercially available and national infrastructure for B-ISDN is ready.
High quality telemedicine will be achieved in the combination of multimedia and communication technology. However, there are many engineering specialists for either side but a few for integrating both technology. Lack of the integrator will interfere the development of the telemedicine. It is emphasized to cultivate integrators and to generate a new field of integrated technology.
Input devices and their standardization for image data exchange must be also emphasized. DICOM (Digital Imaging and Communications in Medicine) standard will be effective for radiological images but another images such as movies are not targeted so far in the medical informatics community. Inter-AV equipment and AV equipment to computers and other peripherals are hardly connected. Standardization for image data exchange between AV equipment and information processing equipment would be a very urgent and important issue.
Doctors generally assume a X-ray film image as a golden standard. If the paradigm is shifted to the acceptance of digital image of 2K x 2K x 10 bit depth as a golden standard, the technological barrier will be much lowered and the cost for development of high quality image- oriented telemedicine will be reduced.
At the time when national level of information infrastructure is arranged, a part of the questions will be solved. However, the others will be especially critical to the further development of telemedicine. International medical informatics community should take initiative to fulfil the goal of telemedicine for the ultimate viability, economical sustainability and efficacy in health care delivery system.
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The study was partially supported by a grant from the Science and Technology Agency of Japan.
Figure 1 Outline of the Experiment 1: HDTV transfer with B-ISDN
Figure 2 Local system configuration of the Experiment 2: SHD Image transfer with B-ISDN
Figure 3 Tele-clinical conference design of the Experiment 2
Figure 4 System design of the Experiment 3; digital HDTV and NTSC image transfer with CS system