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DICOM, PACS, Workstations, Simple Teleradiology - A Do-It-Yourself Primer


A management book that I recently read, talks about how many companies in the early and mid-part of the 20th century made money out of "friction", i.e. the lack, on the part of the customer, of knowledge or information about products, pricing and competition. With the advent of the Internet and improved information flow, "friction" has reduced significantly, but not completely.

A few weeks ago, speaking to a new company that had developed a DICOM-based viewing and archival station, I asked why anyone would buy a product that could be bought free or at minimal cost via the Internet. And the representative too replied, "as long as people are ignorant, we are in business".

Up to just three-four years ago, the modality vendor companies (companies selling CT, MRI, etc) had a stranglehold on the workstation and PACS business, especially in the third-world countries. Some factors that made it virtually impossible to develop workstations and PACS solutions at a reasonable cost were:

  • Lack of understanding of images, proper DICOM-related information
  • Lack of DICOM-compliant machines
  • Proprietary image formats and output devices and
  • The absence of other companies that could provide solutions

Just three years ago, a simple workstation, bought from a modality vendor would have cost anywhere between Rs. 7-10 lakhs (20,000-25,0000USD), if PC based and 15-20lakhs (35,000-45000USD) if Sun Sparc or Silicon-Graphic based.

Today it is possible to completely bypass the modality vendor companies for developing simple workstations and mini-PACS systems because of a number of developments. Modality companies have had to adopt widespread support for DICOM. Access to information and software via the Internet is improving rapidly.

The Internet also provides the ability to communicate through different forums with other radiologists to understand the pros and cons of these companies and their software products. And finally we have the reducing costs of powerful PCs and Ethernet networks,

There are also now many other focussed companies that can deliver workstation and PACS solutions to individuals and hospitals. These include the camera/printer companies and dedicated workstation and PACS companies, which are all competitors in this fast-growing field.

Even these companies however are expensive for developing simple archival and viewing stations, when it comes to ordinary users in third-world countries,

This article therefore is aimed at small hospitals, individual private practices and even government hospitals, which are fund-deprived, and want to develop their own solutions.

It is aimed at those radiologists who are a little computer savvy or have computer savvy people working with them or for them and who can use the Internet and locally available resources to their benefit. Even computer un-savvy radiologists can do this with a little help from their "friendly neighborhood" computer vendor or networking specialist, who luckily thanks to the computer and last year's dot-com revolution are available by the dozen, even in small towns.

Alternatively, after understanding what is involved in setting up such a system, radiologists may still opt to deal with a company (for "peace-of-mind" and "support"), rather than to develop their own solutions. Hopefully, the knowledge gained from this article may allow them to leverage with these companies better.


Understanding Terminology and a Few Definitions

Before we go ahead with the step-by-step description of what is involved in developing simple viewing and archival stations and workstations, I would like to run through some basic terminology.

1. Modality

Any system capable of generating an image. E.g. CT, MR, USG, X-ray (with CR or DR systems) and even pathology, ECG, etc.

2. Camera/Printer

This is the output device either film-based or paper-based. If the camera/printer is part of the DICOM network, any modality in the network can print to the camera/printer even without a direct cable connection between the camera/printer and the modality.

3. DICOM - Digital Communications in Medicine

A standard partly created by ACR-NEMA in conjunction with various vendors. It defines the structure of an image in terms of its headers and the image component. We do not need to actually understand the technicalities of this. The images are usually saved as .dcm images.

4. DICOM Compliance Statement

A statement that modality vendors make, defining how compliant they are with DICOM standards. As a rule, American and European companies are more DICOM compliant than Japanese companies

5. DICOM Print, Send, Receive, Store

Different functions based on the DICOM image that the various machines should have. Some of the earlier machines may have some of these, but not all. Many times, even if the functions are present, the vendors don't explain this to or "hide" their presence from their customers

6. Ethernet, LAN & TCP/IP

LAN stands for Local Area Network and implies the presence of two or more computers that are networked together; i.e. they communicate with each other, using Ethernet cards and cables. Wireless connections are also now possible. "TCP/IP" is the usual protocol used by an Ethernet based LAN for facilitating communication between the various computers. TCP/IP is incidentally also the protocol used to connect to the Internet.

7. PACS (Picture Archival and Communications Systems)

In a simplistic sense, a PACS would imply any solution that allows archival of images and communication between two systems, whether it is between two or more modalities or between modality(s) and a viewing station. A printer/camera is also part of this system.


The Steps (1-6)

Step 1:

Getting an Undertaking from the Modality Vendor for Basic Support

When we buy DICOM ready machines, it is necessary to get in writing from the vendor, they it will support DICOM connectivity. DICOM Send, Receive, Print and Store should be available and an Ethernet port should be available. If the camera is going to be on the DICOM network, then all this will be available by default. We should get the camera engineers and the modality engineers to talk in advance so that their respective needs are understood; the camera engineers will see to it that the modality has what it needs for the DICOM network.

Irrespective of the camera vendor though, the modality vendor must be made to commit to support DICOM connectivity. There are many reasons for this. When images have to be sent from the modality to the workstation, it may be necessary to enter the service mode on the modality, to define and identify the workstation computer, to set TCP/IP settings and to configure certain ports. We need engineers from the modality vendor to enter the service mode. Some companies have extremely user-unfriendly interfaces and it makes sense to have the company engineers around. It may also be a good idea to make the camera and modality companies both agree to a couple of joint sessions in your setup, when the DICOM network is being installed.


Step 2:

Basic Groundwork: Buying a Computer and Setting up a Basic Network

It is advisable to buy a new workstation computer rather than to upgrade from an old one. The type of computer will depend on your needs. If the need is restricted to viewing and archival, a standard current Pentium III with at least 128MB RAM and a 20GB hard disk is enough. If we need to install 3D and other software, it would be advisable to go for a dual Pentium processor with 512MB or 1GB RAM. Irrespective of the configuration, the computer needs to have an Ethernet card. The OS (operating software) should preferably be Windows NT workstation or Windows 2000, which are more stable than Windows 98 or Windows ME. For archival, a good CD-writer is a must. For viewing, a good 17" or 19" inch monitor is advisable. The computer cost would range from between Rs. 30,000 to Rs.1,00,000 (1,500-3,000USD) depending on the configuration.

If the installation is new, then the appropriate computer cables should be laid out from the hub to the various devices that are expected to be on the network. The hub is a small device that acts as a central "switch-board". Cables from all devices and computers come to it; information from one computer to another is relayed through the hub. Typically, the network would consist of the modality computer, the camera, the workstation computer and all other computers (reporting, patient registration, doctor's personal computer, etc) depending on the setup. The hub costs around Rs 10,000. Cables and connectors are not very expensive, It is worth buying high quality cables and connectors - this will save lot of heartaches later on, and is a must for data transfer of images

Recommended cables are UTP cables with RJ45 gold connectors. These are the best quality for networks where there is high-value data transfer (large amounts, or high quality images). The crimping of the cables with connectors should be carried out properly and cables should run through channels on walls, and not dangle loosely across computers/hubs. Also ensure that there is adequate space between these data cables and electrical cables (at least 6" would be ideal).

It is of course, not necessary to have a hub or a complex network. A single cable between the modality and the workstation PC can also suffice, and may be the best solution in an existing setup where the camera is non-DICOM and/or where laying cables is a problem.

It is also a good idea to involve a local computer person with networking experience; these as I said earlier, are available by the dozen and the person who sells you your computer (unless you are buying branded PCs), will also provide this support at minimal to no extra cost. The local person/company can thus work with the interior decorator or electrician to ensure correct laying of the cables and make sure that the network is functioning correctly, at least between the workstation computer and the other PCs such as the reporting or patient registration PC.




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