DICOM Validation

An Introductory Guide to DICOM Validation
For Imaging Informatics Professionals

DICOM validation is the process of verifying that a DICOM file is compliant with the DICOM standard. This can be difficult, especially if you are unfamiliar with the standard. 

In this guide, we will walk you through the process of validating a DICOM file and explain how to fix any errors that may occur.  Admittedly this material may be more difficult for a prospective PACS administrator to grasp immediately.  This content may be more suited for PACS admins and analysts with previous DICOM troubleshooting experience.

We’ll try to break it down to make it as simple as possible.  Let’s get started!

What Is DICOM Validation, And Why Is It Important?

DICOM validation is the process of verifying that a DICOM file is compliant with the DICOM standard. This is important because non-compliant files may not be readable by certain medical devices or software. In some cases, they may even cause errors.  Or in a worse case scenario, cause a system crash.

Note:  When we say DICOM files we are referring to medical images and associated data objects within a study such as an MRI, CT, Ultrasound, etc.  A single study can contain several DICOM files.

Compliance with the DICOM standard is important for ensuring that your medical images can be read and interpreted correctly.  Non-compliant DICOM files may cause the following problems

• Inability to store – causing a partial transfer, failed transfer or stuck transfer 
• Able to transfer the file but unable to open 
• Able to open the file but unable to view images
• System hangs, freeze or crash when file is upon transfer completion
• System hangs, freeze or crash when file is opened or viewed

DICOM validation is an important part of the workflow for anyone who works with medical images. By ensuring that your DICOM files comply with the DICOM standard, you can avoid any potential errors or issues.  

If you work with medical images, you may come across these issues.  Especially if you are involved in the radiology records department where you intake several types of DICOM CDs/files from other institutions.  You may already understand how compliance with the DICOM standard is essential. Especially for external CDs.  If these issues do occur, however, PACS administrators can perform a DICOM validation.  

What Are The Steps Involved In The DICOM Validation Process?

The DICOM validation process is designed to ensure that images conform to the DICOM standard.

• The first step is to check that the image file format is valid. This can be done using a DICOM viewer or a DICOM validator.
• Next, the DICOM tags are validated for adherence to the standard
• The image pixels are checked for conformance with the DICOM standard.
• Finally, the image is checked for correct orientation and position.

If any of these steps fail, the image will be rejected and not viewable.

The DICOM validation process is essential for ensuring that images are compatible with the DICOM standard and can be viewed by all patients and doctors.

How Can You Fix Errors That Occur During Validation?

If an error occurs during the DICOM validation process, it is usually due to one of three things:

• The image file format is not valid.
• The image pixels do not conform to the DICOM standard.
• The image orientation or position is incorrect.
• The values in the DICOM tags are incorrect
• If you encounter an error, the best course of action is to try and fix the issue and then re-run the validation process.
   

If you cannot fix the issue, you can always contact a DICOM expert for help.
What if you’re the DICOM expert in your facility?  Well then you might already perform the following…

Real World Scenarios

DICOM from External Organizations

We’re going to use the example of fixing DICOM studies that come in from external facilities.  Whether via CDs or electronic image sharing.  As this is a common challenge for most healthcare institutions.

Below are some common issues for invalid DICOM tags specifically.  Along with possible resolutions in real world situations.

• Patient ID (0010,0020) field is blank
  • Front End UI
    • Radiology records staff can manually enter an MRN into the blank field upon CD upload.  If their software allows.
  • Back End UI
    • PACS administrators can manually enter an ID
    • PACS administrators can create a rule on ingestion to automatically replace the blank field with valid characters 
    • PACS administrators can configure an auto HL7 reconciliation feature to replace the blank PID field with the patient’s known MRN.
      
• Patient Birth Date (0010,0030) is not valid
  • Front End UI
    • PACS administrator or film staff can manually edit this field depending on their PACS, Image Sharing, or CD intake software
  • Back End UI
    • PACS administrators can create a rule on ingestion to flag the study and create a notification if the format does not match [1-2][0-9][0-9][0-9][0-1][0-9][0-3][0-9].  Then set a temporary valid DOB automatically. Or manually enter the correct DOB.
      
• Study Description (0008,1030) too long
  • Front End UI
    • PACS administrator or film staff can manually edit this field depending on their PACS, Image Sharing or CD intake software 
  • Back End UI
    • PACS administrators can create a rule on ingestion to automatically truncate the study description field.  According to the standard the value representation (VR) of this tag is a long string (LO).  Meaning the character limit is 64 characters.  Therefore a rule to remove any trailing characters after 64 should allow this study to be stored.  A separate rule can be set to flag the study for operational staff to verify.

• Transfer Syntax (0002, 0010) not supported
  • We discussed transfer syntax in a previous module.  This DICOM tag provides a UID value that states what transfer syntax or encoding is being used for this DICOM file.  The solution is not as easy as editing the tag value.  The encoding for the file itself must be changed.
  • Front End UI
    • Front end staff may not be able to do anything for these files.  They may or may not see an error on their application UI.  Sometimes staff ask the sending institution to resend the study in a different format.
  • Back End UI
    • Some image sharing software allow you to transform the encoding to a different encoding.  For example, you can uncompress a compressed file in some cases.  PACS administrators can set a rule to transform certain transfer syntaxes to the default transfer syntax (Implicit VR Little Endian) so it can be accepted by internal systems.   If the PACS administrator knows what the preferred syntax of the internal system is, they can transform it to that instead.  For example Explicit VR Little Endian.  Common transfer syntaxes that may cause issues are JPEG2000 and Explicit VR Big Endian.
    • The above transform can also be done through a DICOM router or a 3rd party tool

Some DICOM software will allow users to edit these invalid DICOM tags right in the user interface.  However, some tags cause more serious issues that don’t allow the study to be stored.  Or even worse, causing the system to crash.  For these tags, it’s important for admins to create rules that fix the issue on ingestion automatically.

DICOM from Internal Devices

It’s important to note that validation must be performed to fix studies when they are inbound from external facilities.  However, if you are getting bad DICOM from studies within the facility then you must address the issue at its source.  For example, if one of your own modalities is sending invalid DICOM, you must work with the modality vendor to correct the issue on the modality.  If the source is an internal DICOM application, you must address the issue here.  If for some reason you cannot fix the bad DICOM at the source modality or application, you may route the study through an application that can transform the DICOM for you based on rules.  Automation and resolving the issue at the source is paramount to prevent staff from performing redundant manual fixes.

What Are Some Of The Benefits Of Validating Your DICOM Files?

Validation establishes compatibility with the DICOM standard. Users can be rest assured the studies are readable by any DICOM-compliant device. This is important for two reasons.

1. First, it helps to ensure that your images will be of the highest quality and will not be lost or corrupted during transmission.
2. Second, it allows you to share your images with other medical professionals, regardless of what type of equipment they are using.
   

There are several benefits to performing DICOM validation, including:

• Ensuring adherence with the DICOM standard
  This is essential for ensuring interoperability between different systems and avoiding problems when exchanging images with other organizations.
• Improving patient care
  By ensuring that images are exchanged correctly, DICOM validation can help to avoid errors in diagnosis and treatment.
• Reducing support costs
  Validating your implementation can help to identify potential problems early on before they cause major issues or require significant support from your vendor.  

Therefore, validating your DICOM files is an essential step in ensuring the quality and interoperability of your medical images.

FAQs

DICOM is the industry standard for communication and image exchange in healthcare. However, due to the complex nature of the DICOM standard, many organizations are not aware of the full potential of DICOM or how to effectively validate their DICOM implementations. 

Here we will answer some of the most commonly asked questions about DICOM validation and guide ensuring compliance with the DICOM standard.

What kind of things should I look for when validating my DICOM implementation?

Some of the things you should look for when validating your DICOM implementation include correct encoding of data elements, adherence to transfer syntaxes, and support for required profiles. Such as those needed for HIPAA compliance. 

You should also verify that any customizations you have made to your implementation do not violate any of the rules specified in the DICOM standard. In addition, it is always a good idea to test your implementation by exchanging images with another system or organization to ensure interoperability.

Why do I need to validate my device’s DICOM interface? 

The FDA requires manufacturers to validate their medical devices according to industry standards like the IEC 62304 series or ISO 14971. Following these standards helps to ensure the safety and effectiveness of your device. Part of validation includes verifying that your device can communicate correctly with other devices via the DICOM standard. 

What methods can I use to validate my device’s DICOM interface? 

Some common methods for validating a device’s DICOM interface include manual testing, static code analysis, and unit testing. 

Depending on your development process and product risks, you may need to combine multiple validation techniques to get comprehensive coverage. 

What tools do I need for DICOM validation? 

You may need a DICOM viewer and some images in the correct format for manual testing. Microdicom is a free 3rd party software that allows you to view DICOM images and its DICOM header.  Free software like DVTK have validation tools that can help identify bad DICOM then provide the error reason.  You will be able to edit the DICOM tags manually to correct them.

If you want to automate your testing process or do static analysis, you’ll need a tool that can read and manipulate DICOM files. For example a tool that can transform DICOM tags on ingestion.  Or a router that can perform conditional formatting based on set criteria.  Usually these advanced tools are provided by various software vendors.

Conclusion:

Hopefully, this FAQ has given you a better understanding of what’s involved in validating your DICOM files. As you can see, doing so has many benefits; including ensuring interoperability, improving patient care, and reducing support costs. 

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