Imported: Cross-Sectoral Image Data Integration – DICOM Link Exchange (DLX) DIN/TS 19455. A Review

Abstract

Background

The use of download links instead of physical patient CDs requires new standards that are able to integrate these virtual media into clinical processes.

Method

Due to the challenges in practice, a DIN working group on QR codes and online availability of image data was launched in 2023 by the German Radiological Society (DRG) and the Professional Association of German Radiologists (BDR). Its members, i.e. users and manufacturers, developed solutions with a focus on state-of-the-art technology, fulfilment of legal requirements, practical usability, and implementability. Additional framework conditions to be considered were data transfer as an HTTP link and the use of ZIP containers with a mandatory IHE PDI media structure that can optionally be supplemented by an IHE XDM media structure.

Results and Conclusion

The results are summarized in DIN/TS 19455 DICOM Link Exchange (DLX), which defines the content of the media for the transmission of access data, the content and format of the virtual patient CDs, as well as an OpenAPI-based interface for automated data access. In addition, DIN/TS establishes the minimum functional requirements for manual data access.

DICOM Link Exchange enables the integration of virtual patient CDs in clinical processes and has the potential to replace physical data media. In combination with the MIO Image Report and the use of the gematik email service KIM for data transmission, there is now the possibility of a nationwide digital exchange of radiological images and reports without a complex infrastructure.

Key Points

• DLX enables the integration of virtual patient CDs in clinical workflows.

• DLX has the potential to replace physical patient CDs.

• DLX can speed up digitalization in healthcare.

Citation Format

• Kämmerer M, Engelmann U, Eßeling R et al. Imported: Cross-Sectoral Image Data Integration – DICOM Link Exchange (DLX) DIN/TS 19455. A Review. Rofo 2025; DOI 10.1055/a-2548-1836

 

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Keywords

PACS - teleradiology - digital radiography

Introduction

Twenty years ago, when patient CDs replaced film as the medium for sharing radiology examination data, the new CD media’s lack of interoperability created significant challenges for the radiology community.

In response, the German Radiological Society (DRG) launched its Media Exchange Certification Project [1], which received technical support from the OFFIS Institute, in order to promote interoperability for media content and standardize import processes. Twenty years later, a new challenge faces users as virtual media, e.g. download links and QR codes, are replacing physical data storage devices. Additionally, the interfaces for the file sharing solutions currently available commercially vary greatly in terms of their operation and the range of functions provided. Similar to 20 years ago, working with new media is once again disrupting established processes.

This time, however, DRG has taken a different approach. Together with the Professional Association of German Radiologists (BDR), the DIN Standards Committee for Radiology [2] founded a working group on QR codes and online availability of image data. The result is the DIN/TS 19455 DICOM Link Exchange (DLX), which promotes standardized processes for working successfully with these new media.

 

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Materials & Methods

The DIN working group on QR codes and online availability of image data was launched officially in 2023 at the German Radiology Congress in Wiesbaden. Under the leadership of the DIN Standards Committee for Radiology (NAR), it included 17 members representing industry and users.

At the first meeting, it was agreed that the resulting technical specification (DIN/TS) should whenever possible be based on existing standards, and the specification must also provide a solution that allows its users to process transmission data both manually and automatically.

To further develop the technical specification, the working group first divided itself into four subcommittees based on the following topics:

• Authentication

• Electronic availability of examination data

• End user interface

• Transmission medium

Based on each of these topics, the respective subcommittee members reviewed the best available technology, the legal requirements, and, if relevant, existing standards, in order to develop solutions for ensuring the online availability of patient CD content. Moreover, content was not restricted to radiological data.

In addition to accessing the application data via an HTTP link, the basic conditions that had to be taken into account included that solutions focused, in particular, on the perceived usability by end users, data security, data privacy, and at the same time the ease with which the solution could be implemented using commercially available products. Furthermore, the media structure for the data transmission format had to be defined by the IHE Portable Data for Imaging (PDI) profile [3] [4] or, optionally, by the IHE Cross-Enterprise Document Media Interchange (XDM) profile [4] [5] in the form of a ZIP container [6]. These basic conditions were unanimously agreed and adopted by the working group members during the first two meetings.

The subcommittees’ findings were discussed with all members of the working group at monthly meetings.

The findings adopted by the working group were then gradually incorporated in the text of the new DIN/TS. The public comment period for this initial draft [7] followed in the summer of 2024 and ended in early October 2024. The feedback obtained was incorporated in the final version of the standard. The DIN Standards Committee for Radiology officially approved this version on December 18, 2024, clearing its way for publication by DIN.

 

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Results

The results essentially consist of the following three definitions:

• The form and content of the application data media

• The form and content of the access data transmission media

• The standardization of access to application data

Application data medium

DLX requires a ZIP container to transfer application data ([Fig. 1] DLX ZIP container structure), where the mandatory internal structure of the ZIP container corresponds to the IHE PDI definition for the medium [4]. As an option, the media structure can also be combined with the structure described in the IHE XDM profile and expanded accordingly (4.47.4.1.3.4.1 Grouping with XDM (IHE ITI Technical Framework)) [8].

Fig. 1 DLX ZIP container structure.

Additional files can also be stored directly at the root level of the DLX ZIP container, as well as in other subdirectories, provided they do not conflict with the definitions of both the IHE PDI and XDM profiles. Handling this additional content is not covered by DLX.

 

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Access data transmission media

Access to the linked application data requires access information on the recipient side. In practice, the storage media currently available are paper printouts, electronic transmission methods, such as email or SMS, or verbal transmission. In view of legal requirements (GDPR, §218 German Criminal Code (StGB), etc.), no confidential content (such as passwords) may be transported via insecure channels without the explicit permission of the person concerned. The previously mentioned transmission methods/channels currently available in practice generally require two media/transmission methods for legally compliant transmission, e.g. two paper printouts, paper printout and email, email and SMS. The DIN/TS DLX standard takes this into account. The standard defines the content required for use in practical applications.

The following boxes 1 and 2 list the most important contents of the access data media, which allow users to handle the access data in a simple and standardized manner. From a user perspective, the requirements of particular note are that download links are as short as possible and characters used are unique, as well as information about the validity of the access data and how this can be extended, if necessary.

The use of two access data transmission media is not required. This depends on the use case. The contents described by DIN/TS can also be transmitted using only one medium, provided that the legal requirements for data protection and security are met.

 

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Access to application data

For access to application data, DLX specifies the HTTPS transmission protocol, for which an interface based on the OpenAPI standard [9] [10] is additionally specified for automated access. In addition to the introduction of the private HTTP header tag X-DICOM-LINK-EXCHANGE, the OpenAPI DLX API essentially defines three endpoints:

• The automated login.

• The list of data available for download.

• The download of the data at ZIP container level as well as at individual file level.

In the absence of the X-DICOM-LINK-EXCHANGE tag, the servers respond as before by accessing the website, where users can manually view or download the shared application data. As an improvement over the previous behavior of the various program interfaces, DIN/TS requires that the endpoints defined by the DLX API must also be available directly at the top program level or immediately after a successful login, even for non-automated manual access. This means, for example, that the options for downloading radiological image data are available directly at the program level after the user has logged in.

 

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Discussion

Application data medium

The requirement to build the media structure on the IHE PDI profile derives from its use worldwide. The vast majority of commercially available DICOM archives (PACS) can handle such media. The option of adding content to the application data medium in accordance with the IHE XDM specifications now also makes it possible to transfer files in other common file formats such as PDF and JPEG in a standardized manner in the patient context, in addition to pure DICOM files and to import them after receipt.

 

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Access data transmission media

In practice, the content of the media in use today causes problems on a daily basis due to its handling. Often enough, difficulties arise when scanning QR codes and then the link needs to be entered manually. Due to the lack of length restrictions and ambiguous characters, input errors are now commonplace. The length restriction and the additional requirement for uniqueness of the characters used thus reduce important sources of error. Without any indication of the validity period, data access is often denied currently in practice, resulting in time-consuming interruptions in the import process. By providing the expiration date together with information on how the period of validity can be extended, these problems should become a thing of the past, even if, as is common today, the appointments between the radiology examination and the follow-up treatment appointment lie far apart.

Separating the password information and transmitting it via a separate medium also makes sense in practice. This ensures that the patient can continue to retain control over access, while preparations for data import can be made by non-medical staff. Or, there is the possibility of electronically transmitting the non-confidential part of the access data via insecure channels, such as email, if this better suits the processes for the respective use case. Identification of the access data transmission media also ensures that the information is clearly assigned and enables the risk of confusion to be minimized even when dealing with large volumes of these access data transmission media.

 

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Access to application data

Until now, the commercially available solutions have focused on manual access by users. The lack of standards results in serious problems in everyday use. Each data sharing solution has a different interface, with the result that it is not transparent for users where in the program the function for downloading the image data or viewing the data online is available, or even whether it is available at all. DLX now makes it clear which functions must be present at which point in the program logic. If users do not find a feature, they can be sure that the corresponding function does not exist in the software they are using. If a manufacturer declares conformity with DLX, it becomes clear to users, for example, that there is a download of shared data or the import of DICOM objects at least at the examination level, depending on the type of software (download portal, data importer).

The definition of the DLX API now goes a decisive step further and enables automation of the import of data linked to a download link. Despite the need to enter a second factor to access the download data, these functions can now be integrated in the workstation interfaces – regardless of which provider makes the downloads available. This ensures that data import processes can also be defined for the virtual media provided via QR codes, similar to those processes for reading the former patient CD data carriers – and potentially even more efficiently, because the DLX API also provides targeted access to individual files.

 

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Outlook

DIN/TS 19455 DLX is one step further in the era of digitalization in healthcare, and it integrates radiology and its image data in newly emerging processes. In the next step, the contents of the radiology report should also be made available, together with the underlying image data, for all treatment processes.

This could be achieved by combining different standards. As part of the digitalization of the healthcare system, new standardized data structures, or medical information objects (MIO), are being defined on an ongoing basis for Germany. These objects enable the interoperable exchange of structured and thus machine-readable data. They have already been described and published for various application areas, such as vaccination records, maternity records, and patient summary files.

The electronic format for the radiology report is currently being developed in the form of the MIO imaging report [11]. This definition is about to be released for public comment. Among other things, MIOs make it possible to provide a reference (link) to the image data. This meets the prerequisites for communication between the two definitions of DLX and MIO imaging report. For the type of targeted communication that is typically required between two healthcare providers, this step would allow for automated transmission of radiological data, together with structured content information, without the mandatory need for a complex infrastructure to map access rights. By further combining it with an established and secure transmission channel, such as the TI service KIM (Communication in Medicine) [12], the majority of today’s existing communication needs in patient care, where radiology is involved, could be solved directly and across Germany.

In order to take the next step of transferring data to practical applications, discussions are already under way between project managers for the MIO image report (MIO42) and gematik, the national agency for digital medicine, in conjunction with representatives from the user community and manufacturers.

 

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Interessenkonflikt

All authors affiliated with a company are employed by companies that might develop commercially available products using DLX. Dr. Marc Kämmerer – Employee of VISUS Health IT GmbH Dr. Uwe Engelmann – Employee of Nexus/Chilli GmbH Ingamr Gergel – Employee of mbits imaging GmbH Dr. Daniel Haak – Employee of VISUS Health IT GmbH Michael Herbrik – Employee of der easyRadiology AG Thomas Jumpertz – Employee of Sectra Rainer Kasan – Employee of Digithurst GmbH Klaus Moritz – Employee of Phönix-PACS GmbH Sacha Romtzeck – Employee of DECOM Engineering GmbH Samrend Saboor – Employee of Siemens-Heathineers AG Raimund Schneider – Employee of Digithurst GmbH Florian Schwind – Employee of Nexus/Chili GmbH Anna Stadler – Employee of Dedalus HealthCare Ges.m.b.H Sergej Werbolowski – Employee of easyRadiology AG

• Literatur

• 1 Deutsche Röntgengesellschaft e.V. and Kuratorium OFFIS e.V. Testat-Projekt für Datenaustauschmedien der Deutschen Röntgengesellschaft e.V. – Anforderungskatalog für Datenträger mit Patienteninformationen. 2006 Zugriff am 14. Januar 2025 unter: https://dicom.nema.org/dicom/minutes/Committee/2007/2007–11–29/Other_Documents/DRG-Anforderungskatalog-2006_Comment.pdf
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Publikationsverlauf

Eingereicht: 23. Januar 2025

Angenommen nach Revision: 18. Februar 2025

Artikel online veröffentlicht:
17. März 2025