DICOM 101
In this FAQ-style article, I want you to introduce the DICOM standard for the absolute beginner.
Motivation Behind Standard
It was early 1980s when medical imaging started to digitize. Digitization of medical imaging came with big problems as well.
In the beginning…
There were different devices with different functionality from different vendors in the market. This heterogeneous ecosystem was very difficult for anyone other than manufacturers of devices to decode the images that the machines generated, or to print them.
Industry need to ensure long lifespan of its million-dollar investments considering systems will be in operation for 20 years keeping patient history for a very long duration due to regulations.
Avoiding the Tower of Babel Problem
In 1983, The American College of Radiology (ACR) and the National Electrical Manufacturers Association (NEMA) joined forces and formed a Standards committee to meet the combined needs of radiologists, physicists and equipment vendors.
What does DICOM stand for?
Digital Imaging and Communications in Medicine. DICOM is a standard that specifies a non-proprietary data exchange protocol.
What does DICOM Standard define/specify?
It mainly defines the network services for image transmission, archiving, retrieval from archive of medical images.
Where is DICOM being used?
DICOM is being used in every medical branch that utilizes imaging, for example: cardiology, mammography, radiology, surgery, endoscopy, dentistry, pathology.
Who is the publisher?
There is an international DICOM committee who are listed in https://www.dicomstandard.org/members page. The members are grouped into three categories;
- Manufacturers: such as Agfa, Philips, Siemens, etc.
- Users: such as ACR (American College of Radiology), European Society of Radiology (ESR), etc.
- General Interest: such as China Institute for Medical Imaging and Communication Standards (CIMICS), etc.
When was the first version published?
First version 1.0 was published in 1985.
https://www.dicomstandard.org/history
Is there any new versions since then?
Yes, sure. DICOM is an evolving standard.
First version was supporting only point-to-point transmission over parallel interfaces. In 1993, with version 3.0, TCP/IP support was added to the standard. As the imaging technologies excel, DICOM added support to them. Still in 2022, there are new version still being published.
Is this a US-only standard?
No.
EN 12052 makes DICOM an official European Standard. Also ISO IS 12052 makes DICOM an international standard. Please note that these standards does not include any change and they are just references to the original DICOM standard.
How big is DICOM standard? Can I read it in a week or so?
It depends on your reading speed. 😃 The standard is over 7200 pages in 2022. If you’re able to read 3 pages per minute, you can read the whole standard in 40 hours. Fortunately, no one does not need to read all of the standard.
How such a big standard organized then?
It is divided into 22 parts. First 8 parts are the most essential ones.
Where I can find my way then?
Your start point is https://www.dicomstandard.org/current which provides all parts of the standard.
Does DICOM speak HTTP?
Yes and no. DICOM has its own network protocol however Part 18: Web Services (WADO for Web access to DICOM Objects) introduce web services equivalent of DICOM network services. Please note that most of the devices still does not talk web services. So, you need to learn DICOM protocol in any case.
What to do next?
You can start with learning Part 3 for Information Object Definition and then continue with Part 5: Data Structures and Encoding. You can also follow me on Medium for my upcoming articles.
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