The DICOM standard is complicated and different medical devices support it to different extents. For example, a CT scanner may support a certain subset of DICOM’s features and an image archive may support another. Both devices are DICOM compliant but unless they support complementary features, they will not work together.
So what does this mean for medical device buyers, sellers and users? This means that not every DICOM compliant device will necessarily interoperate!
This is where the DICOM Conformance Statement (DCS) comes in. A DCS is a detailed technical document accompanying most devices that outlines exactly which features of the standard are supported. Going back to our example, the CT scanner’s DCS must state that it supports features listed as required in the image archive’s DCS for the two to work together.
SOP, SCU, and SCP 🔗
DCSs use a lot of specific terminologies. Some common ones are SOP (Service Object Pair), SCU (Service Class User), and SCP (Service Class Provider). These terms have very particular meanings in the DICOM standard but for now, you can think of SOP as “some desirable device feature” and SCU/SCP as complementary halves of that feature. The SCP half provides the feature and the SCU half consumes it.
To continue our example from before, for a CT scanner to be able to send images to an image archive, the CT scanner must be an SCU for the “CT Image Storage” SOP and the image archive must be an SCP for it. If both halves of this feature are not present, the two devices will not work together. Even if they are both labeled DICOM compliant!
A DCS (among other things) is a listing of supported SOPs defined as SCU/SCP roles. By comparing this listing between devices, you will be able to determine their interoperability.
DCS Structure 🔗
Although complex, most DCSs have the same document structure. This is by design as the people behind the DICOM standard took great pains to provide detailed templates for the DCS. Here is the high-level structure of a DCS. For details, see the official standard.
- Cover Page: First page containing device name and date.
- Conformance Statement Overview: Layman’s description of device.
- Table of Contents
- Introduction: General information, relevant disclaimers, and terms.
- Networking: Description of networking related services.
- Media Interchange: Description of non-networked media exchange services.
- Support of Character Sets: States supported character sets and encodings.
- Security: Relevant security concerns, descriptions, and disclaimers.
- Annexes
For Medical Device Buyers 🔗
If you are a buyer evaluating a medical device, you should always ask for a DCS. As mentioned above, just because a device is DICOM compliant does not mean it will work with your existing information systems. To make it more concrete, here are some ways in which things could go wrong if you do not evaluate DCSs:
- If you buy a unit that does not support the DICOM Verification SOP SCP, you will never be able to verify DICOM connectivity to that unit from another DICOM device. Verification messages sent to it will remain unanswered, as if the unit either does not exist or has a broken network connection.
- If you buy an archive that supports the MR storage SOP SCP, nothing implies that it should support the CT storage SOP SCP, and you might not be able to transfer your CT data to the same archive.
- If you have a workstation that supports the C-Find (Query) SCU, but does not support the C-Find (Query) SCP, you’ll never be able to query that workstation from another workstation or archive. Only query SCPs can respond to queries, serving those responses to other units.
- If you buy a DICOM teleradiology server that does not support image compression for C-Store image transfers, you won’t be able to send the images compressed; and you won’t be able to run your teleradiology business.
– Digital Imaging and Communications in Medicine: A Practical Introduction and Survival Guide
The list of potential problems is long so play it smart and always ask for a DCS.
For Medical Device Sellers 🔗
If you are a medical device seller, it is absolutely in your best interest to ship your product with an accompanying DCS. It is the only way your potential customers can assess the interoperability of your device with their existing setup.
We can Help! 🔗
DCSs are dense technical documents. If nobody on your team has written one before, it will likely be faster to have a DICOM expert help you write one that you can confidently give to your customers.
We can help you write a statement within a week, but timelines will vary depending on the complexity of your software. Engagements start at $5k. (We can also help modify existing statements.)
Our team of engineers has significant experience working with the DICOM Standard. We wrote the DICOM Standard Browser, partly for our use. It is now the top site for many DICOM-related searches and is used by more than 10,000 engineers and radiologists each month.
