Design of Medical Teleconsultation Support System UsingSuper-High-Definition Imaging System

Takahiro Yamaguchi,1 Toshikazu Sakano,1 Tatsuya Fujii,1 Yutaka Ando,2 and Masayuki Kitamura3

1NTT Network Innovation Laboratories, Yokosuka, 239-0847 Japan

2Department of Radiology, School of Medicine, Keio University, Tokyo, 160-8582 Japan

3National Seiransou Hospital, Ibaraki, 319-1113 Japan

SUMMARY

A medical teleconsultation is a service to connect aprovincial clinic to a central hospital, and enable a centralmedical specialist to offer diagnosis support to a remotedoctor. This research aims to clarify the features requiredto realize such services and such systems. We have con-structed a telemedicine system by combining a high-speednetwork, a medical image database, a super-high-definitionimaging system, and an IP-based video conferencing sys-tem. Based on this system, we developed the medicalteleconsultation support system. Using the system, we per-formed experiments on medical teleconsultation in whichtwo doctors in different places inspected the same imageand discussed the appropriate radiation therapy. Throughthese experiments, we proved the usability of the collabo-rative work functions implemented on the system, such asthe image preloading function to realize high-speed imagedisplay switching regardless of network speed, the synchro-nized image-display function, and the shared pointer dis-play function. © 2002 Wiley Periodicals, Inc. Syst CompJpn, 33(8): 9–18, 2002; Published online in Wiley Inter-Science (www.interscience.wiley.com). DOI 10.1002/scj.10075

Key words: telemedicine; medical teleconsulta-tion; high-speed network; super-high-definition image.

1. Introduction

At present, against the background of informationinfrastructure readiness and digitization of medical infor-mation, hopes are running high that telemedicine servicescan be realized on information communication networks [1,2]. From an international perspective, Massachusetts Gen-eral Hospital has already completed the experimental useof a telemedicine system, and the system is now in regularuse [3]. In Japan, various telemedicine experiments arebeing carried out to realize such services, and their usabilityis being proven [4]. In addition, telediagnosis over a 64-kbps ISDN line is now in regular service [5]. Most suchforeign/domestic telemedicine experiments/services han-dle only relatively low-definition/volume data like CT andMRI images, but the target of our research is the handlingof chest x-ray images. This requires us to handle super-high-definition images which have a volume one to twoorders greater.

Compared to the United States and Europe, Japan hasfew radiation specialists who can diagnose x-ray images,and only a few provincial clinics have full-time access tosuch specialists. Moreover, no specialist can claim to coverall fields, so consultation is often required. If we coulddevelop effective medical teleconsultation services basedon the transfer of super-high-definition x-ray images,

© 2002 Wiley Periodicals, Inc.

Systems and Computers in Japan, Vol. 33, No. 8, 2002Translated from Denshi Joho Tsushin Gakkai Ronbunshi, Vol. J84-D-II, No. 6, June 2001, pp. 1203–1212

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higher-quality medicine could be provided regardless oflocation.

There are some cases in which the radiation therapyspecialist is part-time, although the radiation therapy equip-ment is set up not only at the scene of the image diagnosis,but also at the scene of the radiation therapy. The medicalteleconsultation support system will allow such facilities totransfer the images to a specialist who then decides thedetails of the treatment program, such as irradiation regionand direction. Then, the radiological technologist can irra-diate according to the program. This is useful when urgentirradiation treatment is indicated [6].

While a simple teleconsultation system based onvideo conferencing is already in use [3], no teleconsultationsystem allows the collaborative use of high-quality x-rayimages with remote viewing/diagnosis.

We constructed the telemedicine network testbed IM-PACT (Interhospital Medical Picture Archiving and Com-munication system for Telemedicine), which connects fivemedical facilities around Tokyo and the NTT YokosukaR&D center with a high-speed commercial dedicated line.We are carrying out some experiments to realize varioustelemedicine services including medical teleconsultation[7–9]. This paper introduces a super-high-definition imageviewing station capable of reading chest x-ray images; itwell supports medical teleconferencing. Together with thehigh-speed network of the IMPACT testbed, it allows doc-tors in different places to consult and agree on a course ofradiation therapy. This paper describes the result of experi-ments conducted on the medical teleconsultation supportsystem and consultations on radiation therapy. Section 2describes the IMPACT testbed experiment system. Section3 explains the system’s implemented features that supportmedical teleconsultation. Section 4 describes the medicalteleconsultation experiment conducted and its results. Sec-tions 5 and 6 provide future prospects and a conclusion.

2. IMPACT Experimental System

The IMPACT experimental system consists of threemain components (Table 1):

(1) a high-speed network connecting each facility(2) a medical image database (server system)(3) a super-high-definition image viewing station and

video conferencing terminal (client system)

2.1. Network

As shown in Fig. 1, this testbed network connects fivemedical facilities to the database at the NTT YokosukaR&D center (Yokosuka-shi, Kanagawa). This network hasa star configuration whose origin point is an ATM hub

(FORE ASX-200BX) at the School of Medicine, KeioUniversity (Keio Hospital, Shinanomachi, Shinjuku-ku,Tokyo); routers (e.g., Cisco 4700) are set up in each facility.The NTT Yokosuka R&D center and Keio Hospital areconnected by a 135-Mbps ATM Mega-link, and the medicalteleconsultation experiment sites, namely, Keio Hospitaland National Seiransou Hospital (Tokai-mura, Naka-gun,Ibaraki), are connected by a 6-Mbps high-speed digital(HD) dedicated line. All connections are configured as

Fig. 1. Location of networked facilities in the IMPACTtestbed.

Table 1. IMPACT system configuration

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PVCs (Permanent Virtual Circuits). Thus, the testbed iscompletely isolated from the Internet and other networks,which ensures the security needed to handle medical infor-mation.

2.2. Server system

Figure 2 shows the appearance of the medical imagedatabase server system installed at the NTT Yokosuka R&Dcenter.

Given the importance of the medical data to be han-dled, this system adopts a fault-tolerant configuration byoperating two Sun Ultra2 workstations as primary andbackup servers. The information stored in the database isthe image data itself and additional text data about thehospital, patient, and examination notes, as shown in Table2. The image data are stored on a 230-GB RAID and thetext data are held on a 9-GB HDD. The router and two WSsare connected by FDDI. The database server was imple-mented using reliable Oracle database management soft-ware and Oracle web server software. Using Oracle webserver software, any doctor can execute database operationsvia a familiar web browser, so that operability is excellent.

Database access is controlled/protected by one-timepasswords generated by a card-size random-number-codegenerator (security card, Security Dynamics SecurID card).

The database server installed at the NTT YokosukaR&D center is assuming the role of a future data centerresponsible for the storage/management of medical imagedata. By centralizing the medical images from multiplemedical facilities in the data center, we can expect improvedmedical care efficiency, reduced capital investment by shar-ing information with multiple medical facilities, guaranteedtransparency through the centralized management of medi-

cal information, and better quality medical service throughthe collaboration of several doctors.

2.3. Client system

The client system in each medical facility includes(a) a super-high-definition image viewing station and (b) avideo conferencing terminal (Fig. 3). In addition, the equip-ment used to retrieve medical image data, such as a filmdigitizer, and systems (a) and (b), are connected by Ethernet(100B-TX/10B-T).

(a) Super-high definition image viewing stationImages with various resolutions are used for the

medical application, but to diagnose chest x-ray images

Fig. 2. The remote database server system.

Table 2. Items of retrieval in image database

Fig. 3. The client system.

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only high-brightness, high-contrast, super-high-definition(SHD) images are suitable.

A teleconference system using an SHD color CRTmonitor (SONY, DDM-2802C) has been reported [10], butcolor CRTs have problems in reproducing the definitionrequired and in achieving the brightness desired due to thepresence of the aperture grille. Thus, monochrome CRTsare better for diagnosing chest x-ray images, which areoriginally monochrome. Accordingly, we adopted the SHDmonochrome CRT monitor (DataRay, DR110) used inPACS systems in the United States and Europe (Table 3).

As the database and SHD image-display control ter-minals (SHD image viewing station), we used Windows-NT PCs (PentiumII 300MHz class). The PC was connectedthrough its internal SCSI-I/F to SHD frame memory (NTT,SFM-IVn), which drove the SHD monochrome CRT moni-tor. The frame memory can display 2048 × 2048-pixel ×8-bit-depth gray-scale images. Since the medical imageswere captured with 10- to 12-bit depth, the luminance linearmethod was used on the fly to create the 8-bit images fordisplay; such images provide enough detail to permit accu-rate diagnoses [11].

The control terminal uses Netscape Navigator, a com-mon web browser, to enable GUI-based control of themedical image database and SHD image display. By linkingthe SHD frame memory to the PC, not a workstation, wecould construct a relatively inexpensive system. The systemcan be made less expensive or more compact, by usingPC-card-type internal SHD frame memory [12].

Since this PC works on Windows-NT, permission touse the PC can be managed by user password entry. Evenif someone can access the PC, he still needs to be authenti-cated by the security card before accessing the database toretrieve image data, so only card holders can execute datasearch/view.

Figure 4 shows the security card and the databaselogin form. Each doctor in each medical facility will, at thebeginning of each access session, input his or her loginname, security card ID, and one-time password.

(b) Video conferencing system

When consulting with a specialist, video conferenc-ing systems are effective in reducing overhead costs suchas the time/cost needed to meet the specialist. Though the

doctors do not meet face-to-face, they can get the sameeffect via the video screen. Unlike character-based andvoice-only communication media such as e-mail, chat/IM(instant messaging), and telephone, video conferencingallows the doctor’s identity to be checked on the spot. Thisprevents problems such as people masquerading as doctors.

We use Intel ProShare on MMX Pentium 233MHz-class PCs (Windows95) to realize IP-based video confer-encing.

2.4. Data flow

The data flow in this system is as follows. First, theimage data captured/created at each medical facility areregistered with the database at the NTT Yokosuka R&Dcenter via the network. Each x-ray film image is digitizedprior to registration. Original digital modalities such as CTand MRI are registered by way of the DICOM receiver.

The image data in the database are retrieved by theclient system at each medical facility as required, anddisplayed on the SHD monochrome CRT monitor for diag-nosis and so on.

3. Medical Teleconsultation SupportSystem

3.1. Flow of medical teleconsultation

The flow of medical teleconsultation is shown in Fig. 5.

Table 3. Comparison of the super-high-definition color CRT versus monochrome CRT

Fig. 4. Security card and web-browser form of thedatabase login menu.

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First, the National Seiransou Hospital, namely, thediagnosis support client, digitized the x-ray film images(gray scale, 12-bit depth) needed for the consultation, andregistered them with the remote database. At the same time,text data like handwritten medical reports were scanned bythe image scanner and stored in the hard disk of the localvideo conferencing terminal. The time required depends onthe number of images, but registration took approximately15 to 20 minutes per case (six x-ray films, two medicalreports). The breakdown is as follows: film scan 40 secondsper sheet, database registration 25 seconds per SHD image,document scan 150 seconds per sheet. After registrationwas completed, the video conferencing system was acti-vated and the consultation was begun.

At the beginning of the consultation, text data suchas medical reports were transferred from Seiransou Hospi-tal to Keio Hospital by using the file transfer feature of thevideo conferencing system; the consultation topic was thenconfirmed.

During the consultation, the doctor (client)/specialist(consultant) could switch the image displayed as requiredand discuss treatment plans.

3.2. System overview

The original IMPACT experimental system offeredsuch features as telediagnosis but not medical teleconsulta-

tion. The medical teleconsultation support system, on theother hand, offers an “image preloading function,” a “syn-chronized image-display function,” and a “shared pointerdisplay function” so that discussion between two doctors indifferent places can proceed smoothly. Moreover, its “slideshow feature” allows a group of images to be used intui-tively. These functions are detailed below [13].

(1) Image preloading function

If images must be transferred via the network duringa consultation, network speeds may create delays that inter-rupt the flow of the discussion. Because the image-displaytime depends on the speed of the network, high-speedimage-display switching cannot be done in a low-speednetwork.

To overcome this problem, we defined a hierarchicaldisplay policy as shown in Fig. 6. The image data areretrieved from the following sources in the order shown:frame memory, hard disk of the PC, remote database (whichnecessitates network transfer). Each image can be displayedwithin 1 sec if in frame memory, and about 2 sec if in theHD cache. We can cache more than 100 images (gray-scale12-bit depth) on the PC hard disk, while frame memoryholds 32 images (gray-scale 8-bit depth).

The image preloading function loads the image dataneeded into frame memory and/or the PC hard disk beforethe consultation commences. This allows image display toproceed rapidly and to support the consultation effectively.

As medical consultations are usually scheduled at thedoctors’ convenience, this function is practical.

(2) Synchronized image-display function

To make the consultations really effective, we shoulddirectly control the image display on the partner’s viewingstation, rather than explaining, via the video conferencingsystem, which image is next and asking the partner toswitch the images.

The synchronized image-display function ensuresthat the same image is displayed at both the local and the

Fig. 5. Process flow of medical teleconsultation.

Fig. 6. Hierarchy of the displaying methods.

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remote site. This function includes image-display opera-tions such as zooming into a specific part or altering thedisplayed image by applying another gray-scale conversionrule; these features are seldom used in SHD image diagno-sis.

(3) Shared pointer display function

To make it easier for the partner to discern what theyare looking at, they share the pointer indications. Thiseliminates the need to verbally explain the region of inter-est, eliminates a potential source of confusion, and allowsthe doctors to focus on the diagnosis.

The shared pointer display function makes a pointerindication overlay at the same position of the same imageon both the local and the remote site monitors.

(4) Slide show function

It is time-consuming to retrieve the target imagesfrom the database one by one in the consultation.

The slide show function creates a list of to-be-usedimages as specified by the doctor initiating the consultation;the list also contains meta-data such as the title, patientname, and creation date, which makes it easy to search forand locate the image needed. A series of image data regis-tered as a slide show is transferred to both sites prior to the

consultation by the above-mentioned image preloadingfunction.

3.3. System operations

All system operations are executed via a webbrowser. As explained above, database access can be exe-cuted only after user authentication via a security card.

Before beginning a teleconsultation, all image data tobe used have been registered and some slide shows havebeen formed within the database by the doctor initiating theconsultation.

When starting a teleconsultation, the appropriateslide show can be located by inputting keywords via thequery form shown in Fig. 7(a). The doctor selects the slideshow to be used in the consultation from the resultantslide-show list shown in Fig. 7(b).

At the same time, the home viewing station (localsite) and that of the partner (remote site) should be entered.If image preloading is necessary, a selection must be madebetween frame memory loading or hard disk loading.

On selecting the slide show, the GUI (slide-showdisplaying form) shown in Fig. 8(a) appears and the firstimage is displayed on the SHD monitor. Figure 8(a) showshow the GUI lists thumbnails of the images included in theslide show. The current mark indicates the image currentlydisplayed on the SHD monitor.

Fig. 7. Query form and result of the query.

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With the play buttons, one can switch the displayedimage on the local and remote SHD monitor with next/pre-vious/first/last image in the slide show. By mouse clickingany thumbnail image, one can switch the display to thatimage directly.

By clicking the detail button at the bottom of eachthumbnail image, a 512 × 512 image like panel (b) appearsin the newly opened web-browser window. By mouse click-ing any point of that image, the shared pointer is displayedat the corresponding position on the SHD monitor of bothparties.

The consultation is performed remotely by such op-erations and the conversation via the video conferencingsystem.

4. Experimental Results

4.1. Image display time

The relationship between network speed (bandwidth)and the display time of one SHD image (8 MB, 2048 × 2048pixels, 2 bytes/pixel) is shown in Fig. 9.

By using a high-speed network (45 Mbps or more),image-display switching can be achieved for about 5 to 6seconds at comparatively high speed.

4.2. Network traffic

Figure 10 shows the received data traffic at the Sei-ransou Hospital side during a medical teleconsultation us-ing various image preload configurations: using framememory cache, disk cache, without cache [14].

Fig. 8. Slide-show displaying form and pointer indication.

Fig. 9. Relationship between network bandwidth andrequired image-display time.

Fig. 10. Received data traffic Seiransou Hospital using6-Mbps network.

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If the preloaded image data are cached, the largesttraffic component is IP-based video conferencing, approxi-mately 200 kbps. If there is no cache, the traffic peaksstrongly when image data flow between server and client.

4.3. Doctor’s evaluation

Figure 11 shows a photograph of the medical telecon-sultation during the experiments. Two doctors performedteleconsultations on 54 cases requiring radiation therapy.The doctors’ evaluation of the usability of this system,employing terms such as “response” and “stability,” isgiven in Table 4.

The baseline for the evaluation was real face-to-faceconsultations using x-ray films. As for the SHD imagedisplay, it was evaluated as equal to or better than x-rayfilms in approximately 90% of the cases. A few images werenot perfect because of moiré patterns (caused by film scan-ning) or poor x-ray exposure. Only one system malfunction(server failure) occurred. As for the video conferencingcomponent, the system tended to be unstable and failedtwice (the software package overloaded the Windows95system resources). However, it was evaluated as equal to orbetter than real face-to-face meetings in more than 90% ofthe cases.

5. Discussion

One of the experimental sites, Seiransou Hospital(Tokai-mura, Ibaraki), had been dispatching a doctor toKeio Hospital (Shinjuku-ku, Tokyo) every week to carry

out face-to-face discussions with radiation specialists aboutvarious cases; brought x-ray films were used. As bothfacilities are now connected via the IMPACT network, thedoctors can obtain the opinion of a specialist immediatelywithout traveling to Tokyo. Among 54 cases of medicalteleconsultation experiments, treatment plans for 18 caseswere modified by teleconsultation.

The time taken to complete a teleconsultation variedwith the case, but the average was 18 min (range 10 to 30min), which was longer than that of face-to-face meetings(5 to 10 min). The cause of this gap is assumed to be theoperation time required to switch images and the like; animprovement in usability is expected.

Through the medical teleconsultation experiments,the validity of the following system equipment/featuresused was confirmed:

• SHD image viewing station• video conferencing system• synchronized image-display function• shared pointer display function• slide show function

It took about 5 and 16 s to display an SHD image vianetwork at Keio Hospital (135-Mbps line) and SeiransouHospital (6-Mbps line), respectively. The teleconsultationhad to be suspended until the SHD image was received anddisplayed at both sites. This time lag hindered smoothconsultations. High-speed lines (45 Mbps or more) areneeded if the image preloading function is not used. Be-cause it takes 10 s or more to display an SHD image on anetwork with a capacity of 10 Mbps or less, it is preferableto transmit the image by using the image preloading func-tion beforehand. By using the image preloading functionand slightly decreasing the video conferencing bit rate,teleconsultation can be executed using a 64-kbps/128-kbpsISDN line.

6. Conclusions

We constructed a medical teleconsultation supportsystem by combining SHD imaging systems and collabo-rative work functions. We confirmed the effectiveness ofthe system through teleconsultation experiments.

If we connect provincial clinics in remote locationsto central hospitals by optical fiber, the medical teleconsul-tation support system will provide enhanced medical careregardless of the clinic’s location.

Collaborative work functions between remote sys-tems are mandatory in view of the collaboration betweentelemedicine systems, to enable not only medical telecon-sultation but also medical teleconferencing and the like. Tosupport the connection/collaboration of any system in any

Fig. 11. The teleconsultation experiment.

Table 4. Evaluation of teleconsultations

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hospital/office, multivendor support is required, and a com-mand protocol for collaborations should be standardized[16].

To realize telemedical services, we need to solve theproblems of equipment cost, maintenance cost, and com-munication cost.

Acknowledgments. We are deeply grateful to Ei-ichi Kouda, M.D., of the School of Medicine, Keio Univer-sity who gave us several valuable suggestions, andSadayasu Ono, Ph.D., and Mr. Kazuo Hagimoto of NTTNetwork Innovation Laboratories, who encouraged us inour studies.

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AUTHORS (from left to right)

Takahiro Yamaguchi received his B.E., M.E., and Ph.D. degrees in electrical engineering from the University ofElectro-Communications in 1991, 1993, and 1998. He joined NTT Optical Network Systems Laboratories in 1998 and has beenconducting research on super-high-definition imaging systems and their telemedical applications. He is currently with NTTNetwork Innovation Laboratories. He is a member of IEICE, ITE Japan, and SID.

Toshikazu Sakano received his B.E., M.E., and Ph.D. degrees in electronic engineering from Tohoku University in 1985,1987, and 1998. In 1987, he joined NTT Laboratories, where he has been engaged in research on optical signal processingincluding free-space optical interconnects for parallel computers and free-space multichannel optical switch. Since 1997, whenhe moved to the media processing research group in the same laboratories, he has been active in research and development ofthe super-high-definition imaging system and its medical applications, and medical information networks. He received BestPaper Awards at IEEE’s International Conference on Computer Design (ICCD) in 1990 and 1993. He also received the YoungEngineers Award from IEICE of Japan in 1995. He was an Organizing Committee member of Opto-Electronics andCommunications Conference (OECC) 2000. He is a member of IEEE, OSA, and IEICE.

Tatsuya Fujii received his B.S., M.S., and Ph.D. degrees in electrical engineering from the University of Tokyo in 1986,1988, and 1991. He joined NTT, Japan in 1991. He has been researching image processing and image communication networks.In 1996, he was a visiting researcher at Washington University in St. Louis. He is currently a senior engineer at NTT NetworkInnovation Laboratories. He is a member of IEICE, ITE of Japan, and IEEE.

Yutaka Ando graduated from the School of Medicine of Keio University in 1976, and received his medical degree in1984. He is now an assistant professor there and vice-director of the clinical radiology department. He has specialized inradiological information systems and radiation oncology. His research concerns the teleradiology system, PACS, and theelectronic storage of medical images. He is a member of the Japan Radiological Society (the vice-chairperson of the Committeeon Electronic Informatics Science), the Japanese Society for Therapeutic Radiology and Oncology (the vice-chairperson of theCommittee on Public Relations), the Japanese Society of Nuclear Medicine, and the Japan Association of Medical Informatics(councilor).

Masayuki Kitamura graduated from the School of Medicine of Tokushima University in 1989. He then joined theDepartment of Radiology of Keio University. Since 1997, he has been with the Department of Radiology of National SanatoriumSeiransou Hospital. He is specialized and researches stereotactic radiotherapy of radiation oncology, the teleradiology system.He is a member of the Japan Radiological Society, the Japan Association of Medical Informatics, and the Japan Society ofStereotactic Irradiation.

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