隨著電腦運算能力的增加以及網路頻寬的成長，許多的工作可以在網際網路交由電腦來處理。醫師的工作也不例外，他們可以透過以網頁為基礎的電腦系統來處理他們平日的工作。於是遠距醫療(telemedicine)或遠距會診(teleconsultation)的概念就用來解決遠距離醫療的問題。
　　在一個遠距醫療會診系統，醫師可觀看遵照DICOM 標準所儲存的醫療影像，也可以和其他醫師透過網路討論病患的病情。由於醫療環境對於強健性(robustness)和可靠性(reliability)有較高的需求，因此醫療系統必須在發生錯誤時，快速回復以縮短停機時間(down time)。
　　在本篇論文之中，提出了可以偵測網路連線的錯誤並且處理的方法，以及當使用者斷線之後，可以再次進入會診延續先前的討論過程並且與其他使用者之間同步的機制。利用本論文中提出的懶惰同步機制(Lazy Synchronization)，不論是使用者遲到或因故斷線，都可以在登入系統之後短時間內與其他使用者同步並且繼續會診的討論。

　With the fast growing of the network bandwidth and computing power, many regular jobs can be done on the web through the Internet. Certainly, the physicians and radiologists can also handle their ordinary works on a web-based system. A concept of telemedicine or teleconsultation is proposed to sketch the blueprint of at distance health care.
　In a medical teleconsultation system, physicians can view the medical images which stored in the DICOM standard format and discuss the patients' conditions with other physicians over the Internet. Due to the more robust and more reliable requirements in medical environment, the medical system has to provide less down time than other commercial systems after system failures occur. In this work, some situations that might lead to unstable statuses between client and server are studied. Furthermore, the procedure of synchronization for late users is developed for fast recovery.

References
[1] The American College of Radiology. URL http://www.acr.org/.
[2] National Electrical Manufacturers Association. URL http://www.nema.org/.
[3] Digital Imaging and Communications in Medicine. URL http://medical.nema.org/.
[4] Y.-P. Yu and R. Martinez, "Object Oriented Teleconsultations in Global PACS Using Multi-thread Java," Proceedings of the Thirtieth Hawaii International Conference on System Sciences, pp. 166 - 175, Jan. 1997.
[5] S.-C. Hwang and M.-H. Lee, "A Web-based TelePACS Using an Asymmetric Satellite System," IEEE Transactions on Information Technology in Biomedicine, vol. 4, pp. 212 - 215, Sept. 2000.
[6] A. M. Eldeib and M. M. Bahgat, "SWEAT: Standards Applied in a Web-based Egyptian Asynchronous Telemedicine Project," Proceedings of the 20th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, pp. 1284 - 1287, Nov. 1998.
[7] Z. Chen, X. Yu, and D. Feng, "A Telemedicine System over the Internet," Selected papers from the Pan-Sydney workshop on Visualisation, vol. 2, pp. 113 - 118, Dec. 2000.
[8] J. C. Knight, "Issues of Software Reliability in Medical Systems," Proceedings of Third Annual IEEE Symposium on Computer-Based Medical Systems, pp. 153 - 160, Jun. 1990.
[9] N. Neves and W. K. Fuchs, "Fault Detection Using Hints from the Socket Layer," Proceedings of the Sixteenth Symposium on Reliable Distributed Systems, pp. 64 - 71, Oct. 1997.
[10] F.-J. Tsai, "The design of intelligent replay system for medical tele-consultation review," Master's thesis, National Cheng Kung University, Taiwan, Jul. 2003.
[11] Y.-S. Kuo, "Design for real-time web-based multi-group support tele-consultation system," Master's thesis, National Cheng Kung University, Taiwan, Jul. 2002.
[12] Health Level Seven, Inc. URL http://www.hl7.org/.
[13] The Health Insurance Portability and Accountability Act of 1996. URL http://www.hep-c-alert.org/links/hippa.html.
[14] ComMedica's PIRILIS solutions. URL http://www.commedica.com/pirilis.php.
[15] CHILI Web Site. URL http://www.chili-radiology.com/.
[16] R. Hussein, U. Engelmann, A. Schroeter, and H.-P. Meinzer, "Implementing a Full-Feature PACS Solution in Accordance With the IHE Technical Framework: The CHILI Approach," Academic Radiology, vol. 11, pp. 439 - 447, Apr. 2004.
[17] H. Schulzrinne, S. Casner, R. Frederick, and V. Jacobson, "RTP: A Transport Protocol for Real-Time Applications," RFC 1889, Jan. 1996.
[18] J. J. Hallenbeck and J. B. Dugan, "Design of Fault-tolerant Systems," Proceedings of Third Annual IEEE Symposium on Computer-Based Medical Systems, pp. 162 - 169, Jun. 1990.
[19] B. W. Johnson and J. H. Aylor, "Reliability and Safety Analysis in Medical Applications of Computer Technology," Proceedings of the Symposium on the Engineering of Computer-Based Medical Systems, pp. 96 - 100, Jun. 1988.
[20] M. Back, T. Norgall, M. Rommel, and C. Zywietz, "Internet/Intranet Access to a Multimedia Cardiology Information System," Computers in Cardiology 1999, pp. 81 - 84, Sept. 1999.
[21] J. K. Reynolds and J. Postel, "Assigned Numbers," RFC 1700, Oct. 1994.
[22] J. K. Reynolds, "Assigned Numbers: RFC 1700 is Replaced by an On-line Database," RFC 3232, Jan. 2002.
[23] J. Postel, "Transmission Control Protocol," RFC 793, Sept. 1981.
[24] J. Postel, "User Datagram Protocol," RFC 768, Aug. 1980.
[25] D. B. Johnson and W. Zwaenepoel, "Sender-based Message Logging," Proceedings of the 17th International Symposium on Fault-Tolerant Computing, pp. 14 - 19, Jul. 1987.
[26] E. N. M. Elnozahy, L. Alvisi, Y.-M. Wang, and D. B. Johnson, "A Survey of Rollback-Recovery Protocols in Message-Passing Systems," ACM Computing Surveys, vol. 34, pp. 375 - 408, Sept. 2002.