SYSTEM STRUCTURE OF MMTE

The integrated computing environment consists of fixed host computers and wired-in/wireless mobile client computers (Bates, 1994, Hatfield, 1996; Imielinski & Badrinath, 1994). Fixed hosts (FHs) are connected together via a fixed high-speed network (Mbps to Gbps). The mobile clients (MCs) are capable of connecting to the fixed network via a wireless link. The components in the fixed network are called fixed hosts. Fixed hosts (FHs) provide mobile application services and coordinate tasks to mobile hosts . MCs support query invoking and information filtering from FHs to provide personal information service.

The remote access to image and other related databases may appear like automatic teller machine transactions, but they differ in several respects:

1. They are long-duration transactions requiring the transfer of a large amount of data and require lengthy negotiation, cooperation, pointing, and decisions to reach a final diagnosis and therapy . In this cooperative environment, therefore, we need to sacrifice some of the properties of the traditional transaction model (Krishnamurthy & Murthy, 1992) that enforces ACID properties (atomicity, consistency, isolation, and durability). Note that, in particular, we cannot roll back any transaction in the context of e-surgery. Also isolation implies that the actions of one participant are invisible to another. Therefore, we need to introduce a more realistic model in which the isolation property is removed and intermediate results are made visible so that any catastrophic incidents can be avoided. Also precedence order in execution and context dependencies have to be taken care of. This means we must remove the atomicity constraint that requires "all or none" operation and rollback. This model is called "a workflow model" . More detailed aspects of this model and relevant software design features are described briefly in a later section and in Chapter 2 of this book.

2. A service to permit two users to interact simultaneously with a medical imaging system for cooperative diagnosis. To help diagnosis we need to provide each user with a pointer of a desired identity that can be locally operated and at the same time can be visualised at the remote terminal. This is a concurrent action from two or more users on a read-only image database.

3. Also an audio conference facility is needed for cooperative diagnosis.

4. Collaborative multimedia environment allows medical specialists to cooperate in diagnosis. The environment has to support remote database access for medical images, the retrieval of relevant medical cases to support diagnosis, and communication among participants through telepointers and image annotation for freehand drawing.

5. A telepointing device with a very high reliability.

Thus the key elements in the design of a telediagnostic system are:

1. Design of an appropriate workflow model for telemedical applications.

2. Supporting database access in a mobile cooperative environment for medical images, related text, and video signal images. Also additional support through handheld devices, such as PDAs, for supporting remote information sharing and processing.

3. Providing a cooperative environment for communication among participants audiovisually through telepointers to visualize movements remotely.

4. Appropriate hardware/software tools.

5. Implementation of the reliability, fault tolerance, and recovery features.