Communications and Networks

This module is based on RCPA Guidelines for Digital Microscopy in Anatomical Pathology and Cytology October 2015.

Communication and network configurations are important considerations before acquiring a digital microscopy system for diagnosis as there will be large amounts of data transmitted across the network from scanners to workstations (local or remote), storage devices and the LIS.

For the safe and effective use of the digital microscopy, the IT infrastructure must be able to cope with the increased data traffic, transmit the data securely to protect patient confidentiality and reduce risk of data loss.

Whole slide images (WSI) have, on average, a file size of about 1 GB compressed. With that file size, a fast and effective transmission of the whole image over the internet is impossible. Even on a computer, such an image could not be loaded to the RAM memory completely. It needs certain methods to access WSI, that is, so called “Image Streaming”.

This involves these basic principles:

  • leave the original image on the server,
  • transmit only that image region, which is currently needed on the client side.
  • the server extracts only the current region in the current magnification from the original image, compresses and transmits to the client, which shows it in the virtual microscope.
  • this reduces the data communication to small image tiles, which is comparable to the network traffic of general internet browsing.

The data gets to where it needs to go because of sets of rules known as protocols, which govern the way data travels from one device to another. One such protocol previously discussed (Module 2 Technical Specifications Section 6 File storage and Archive), is hypertext transfer protocol (HTTP). This deals with hypertext documents, or Web pages. Many protocols, such as transmission control protocol (TCP) and file transfer protocol (FTP), break data into packets. Data needs to arrive quickly and with all the pieces in the right order. Too many outgoing streams can overload a server, causing users to see an error message.

For this reason, streaming video and audio use protocols are used that allow the transfer of data in real time. They break files into very small pieces and send them to a specific location in a specific order. These protocols include:

  • real-time transfer protocol (RTP)
  • real-time streaming protocol (RTSP)
  • real-time transport control protocol (RTCP)

These protocols act like an added layer to the protocols that govern Web traffic. So, when the real-time protocols are streaming the data where it needs to go, the other Web protocols are still working in the background. These protocols also work together to balance the load on the server. If too many people try to access a file at the same time, the server can delay the start of some streams until others have finished.

The digital microscopy system should be capable of integration and synchronisation with existing LIS systems to ensure that there is:  

  • no need for double entry of comments,
  • completeness, accuracy and integrity of messages between the digital microscopy system at all times, and
  • any changes to the LIS or digital microscopy systems are synchronised.

The digital microscopy systems should support an open format that can be transformed to the Digital Imaging and Communications in Medicine (DICOM) Standard in the future when the DICOM licensing terms are fully known.

The DICOM Standard, (originally published as the American College of Radiology—National Electrical Manufacturers Association Standard for Digital Imaging and Communications in Medicine; now maintained by the multi-specialty DICOM Standards Committee) specifies a non-proprietary data interchange protocol, digital image format, and file structure for biomedical images and image-related information. Its current structure, which was developed in 1993, provides detailed engineering information that can be used in interface specifications to enable network connectivity among a variety of vendors' products. The Standard describes how to format and exchange medical images and associated information, both within the hospital and outside the hospital (that is, telepathology, teleradiology or telemedicine). DICOM interfaces are available for connection of any combination of the following categories of digital imaging devices:

                (a) image acquisition equipment
                (b) image archives
                (c) image processing devices and image display workstations

                (d) hard-copy output devices.

The general communication model of the DICOM Standard spans both network (on-line) and media storage inter-change (off-line) communication. Applications may utilize any of the following transport mechanisms:

  • the DICOM Message Service and Upper Layer Service, which provides independence from specific physical networking communication support and protocols such as TCP/IP.
  • the DICOM Web Service API and HTTP Service, which allows use of common hypertext and associated protocols for transport of DICOM services.
  • basic DICOM File Service, which provides access to Storage Media independently from specific media storage formats and file structures.

A standard messaging protocol (such as Health Level Seven, HL7) should be used for transmission of information between the digital microscopy system or middleware and LIS. If HL7 is used then it must be compliant to "AS4700.2 Implementation of Health Level Seven".

HL7 and its members provide a framework (and related standards) for the exchange, integration, sharing, and retrieval of electronic health information. These standards define how information is packaged and communicated from one party to another, setting the language, structure and data types required for seamless integration between systems. HL7 standards support clinical practice and the management, delivery, and evaluation of health services, and are recognized as the most commonly used in the world.

Systems must ensure the secure and confidential transmission of all information including images and patient data across private and public networks.

Transmission of data across networks should use secure encryption protocols (such as PKI and SSL) for authentication and to transmit all patient and case data.  A public key infrastructure (PKI) supports the distribution and identification of public encryption keys, enabling users and computers to both securely exchange data over networks such as the Internet and verify the identity of the other party.

Secure Sockets Layer (SSL) is a standard security technology for establishing an encrypted link between a server and a client which is typically a web server (website) and a browser; or a mail server and a mail client (such as 'Outlook'). SSL allows sensitive information such as credit card numbers, social security numbers, and login credentials to be transmitted securely. Normally, data sent between browsers and web servers is sent in plain text—leaving you vulnerable to eavesdropping. If an attacker is able to intercept all data being sent between a browser and a web server they can see and use that information. More specifically, SSL is a security protocol. Protocols describe how algorithms should be used; in this case, the SSL protocol determines variables of the encryption for both the link and the data being transmitted.

A robust firewall should be considered for protection. For example, a web application firewall used to block unauthorised applications (for example, server plugins). A firewall is a network security system, either hardware or software-based, that controls incoming and outgoing network traffic based on a set of rules. Acting as a barrier between a trusted network and other untrusted networks, such as the Internet, or less-trusted networks, such as a retail merchant's network outside of a cardholder data environment, a firewall controls access to the resources of a network through a positive control model. Positive control means that the traffic defined in the firewall policy is allowed onto the network; all other traffic is denied.

A web application firewall (WAF) is an appliance, server plugin, or filter that applies a set of rules to an HTTP conversation. Generally, these rules cover common attacks such as cross-site scripting (XSS) and SQL injection. By customizing the rules to your application, many attacks can be identified and blocked. The effort to perform this customization can be significant and needs to be maintained as the application is modified.

Telepathology is the practise of pathology from a distance, where pathology images and data are electronically transmitted and analysed by a pathologist remotely, typically in real time for the purpose of diagnosis, education or research. There are a number of clinical applications of telepathology in anatomical pathology including, but not limited to, the remote interpretation and assessment of:

  • digital images of anatomical pathology and cytopathology slides;
  • tissue from surgical pathology using frozen sections
  • photographs and medical images

Successful telepathology requires a well-developed communication and network system.
A number of challenges need to be addressed in telepathology as in digital microscopy before it can be adopted for diagnostic use in a pathology laboratory. In summary, these include:

  • formalised standards exist for digital image and data files such as resolution, quality, file format, compression and storage,
  • network bandwidth, as significant bandwidth is required to handle the fast transfer of very large digital image files and data files,
  • ergonomic issues related to physical environment, software and navigational controls,
  • patient privacy issues when using laptops, smartphones, tablets and other devices for viewing digital images and data files,
  • credentialing of the pathologists involved and demonstrated maintenance of their diagnostic skills and knowledge through continuing professional development,
  • medio-legal issues with sharing digital images or data files between pathologists from different organisations or countries, and
  • security of data with regards to access, distribution and the ability to copy or forward to other parties. 

The RCPA Position Statement, Telepathology. February 2016 acknowledges the potential of using digital microscopy systems for diagnosis, with the recent technological advances in digital microscopy systems, storage devices, and communication technology.

For more details on information communication requirements for accredited pathology laboratories see NPAAC Requirements for information communication (2013)

  1. Objective
    To understand the principles of communication and networks to consider when implementing digital microscopy in the workplace for diagnostic use in histopathology and cytology.

  2. Knowledge
    Section1: Configurations
    Outcomes: Understand the principles of communication and network configurations to consider when implementing digital microscopy for diagnostic use, including:

    1. Real time protocols in place;

    2. Capable integration with existing LIS systems.

  3. Section 2: Security
    Outcomes: Understand the principles of security to consider when implementing digital microscopy for diagnostic use, such as:

    1. Secure and confidential transmission of information across private and public networks;

    2. Secure encryption protocols;

    3. Robust firewalls.

  4. Section 3: Telepathology
    Outcomes: Understand the principles of telepathology to consider when implementing digital microscopy for diagnostic use, including:

    1. Formalised standards for digital image and data files;

    2. Network bandwidth;

    3. Ergonomics;

    4. Patient privacy issues;

    5. Credentialing;

    6. Medico-legal issues with sharing digital images or data files;

    7. Security and data.

  5. Behaviours
    Practices the fundamental principles of digital microscopy.

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