DICOM explained Part 1: What is DICOM, DICOM Tags and Data Sets?

Imaging techniques play an important role in many areas of modern medicine. This applies to diagnostics and therapy, but also to research, for example, in the context of clinical trials. The most important medical image format is DICOM. 

Within clinical projects, utilizing our ClinFlows’ solutions to exchange medical images, we frequently meet users (physicians, study nurses and coordinators) who are not that familiar with the topic “DICOM”. Time for us as DICOM experts to start a series in which we explain the format and obstacles that come when dealing with it (spoiler: among others, it’s about personal data!).

In the coming time, we will gradually publish articles here in which we explain the most important background and facts about DICOM data. We start today with part 1 of our DICOM explained-series, in which you will learn what is behind the abbreviation, how the DICOM format is structured, what makes it so characteristic and what it is used for in healthcare.

DICOM: the format behind the five letters

JPEG, TIFF, PNG – almost everyone knows these file formats of images. DICOM is also an image format, but it is used primarily in the medical industry. The abbreviation DICOM stands for “Digital Imaging and Communications in Medicine”. The term already makes it clear that the format not only includes the respective image data, the pixels or its storage as a specific file format, but that the DICOM standard includes further information, which we will explain in more detail later. The DICOM standard has its origins in the 1970s, when it was still called the ACR/NEMA standard and was initiated by the American College of Radiology and the National Electrical Manufacturers Association. DICOM as we know it today has only existed since 1992. The use of this image format is intended to facilitate and standardize the exchange of medical image data.

DICOM: Open standard to exchange medical images

The DICOM format is one of the so-called open standards, openly accessible and usable by anyone. This allows many medical professionals in the fields of research and clinical practice, diagnostics and therapy to exchange, view and perform measurements of medical images independently of manufacturers.

What are DICOM Headers, DICOM Tags and Data Sets?

A set of medical images in DICOM format usually has the following overall structure: Patient – Exam – Series – Images. That is, a patient undergoes a study or examination, such as a computed tomography (CT) scan. This examination consists of several series, and each series contains multiple images (hundreds or thousands) or multiple frames (like a video, e.g., for echocardiographies).

A DICOM medical image file, such as a single CT slice, consists of two distinct parts. One is the medical image itself, the other is the DICOM header. The DICOM header is a block of data that contains specific information that complements the image, called DICOM tags. This usually includes relevant patient data such as name, age, gender and date of birth, but also a lot of technical data and parameters, such as the device used to generate the images, the names of the surgeon and the administered drugs such as contrast agents, as well as data on the imaging technique, such as pixels, matrix size or the dimensions of the image. This usually facilitates the assignment of an image to a patient. In medical jargon, this data is referred to as attributes. Depending on the image and the circumstances, certain information is mandatory, while other attributes are optional. In addition, the DICOM header has DIN standards, which are defined by law.

What are DICOM Tags good for?

The DICOM Tags are organized as a constant and standardized series; thus, they are used in the management of information belonging to medical image data. The DICOM Tags are assigned as metadata elements to each image object in medicine. These can be segmentations, definitions of surfaces, and registration numbers for the images. The format is used for both standardization and storage of the files, as well as a uniform communication protocol for sharing. As data elements, tags consist of an attribute that is used for identification. Usually they are composed of hexadecimal numbers (XXXX,XXXX) with a comma in the middle. If necessary, a further subdivision into the group and element number is possible. In this way, DICOM tags are easier to read, and patient data can be printed directly on them when developing X-ray images. In this way, the X-ray image and the associated data are combined digitally in one file.

What DICOM Tags are available?

There are a variety of DICOM tags that assist in organizing medical image data as well as searching for them. These include, for example:

Accession Number0008,0050
Procedure Creation Date0014,4076
Patient’s Birth Name0010,1005
Operator’s Name0007,1070
Patient’s ID0010,0020
Patient’s Birth Date0010,0030
Patient’s Body Mass Index0010,1022
Table 1, DICOM Tags

Thanks to the numbers, an extremely large amount of information can be assigned to the images, which is immediately recognized by the medical authorities. By the way: A full list of all DICOM tags can be found at MITA (The Medical Imaging Technology Association) or NEMA here.

In the next part of our DICOM explained series, we will dive deeper into the topic: Among others, you will learn more about the problems that the data contained in DICOM files pose for working with them. Stay tuned!

Case Study Clients decidemedical

Case Study: How to send angiograms in DICOM format in investigator-initiated multicenter coronary stent study COMPARE 60/80 HBR

The collection of medical images often plays a vital role to analyze the efficiency of new treatment options researched in clinical studies. The safe and regulatory compliant transfer of DICOM images from the participating sites to the Corelab must be realized in a user-friendly manner. A special challenge is the typically small budgets available for investigator-initiated studies and still, a regulatory compliant way has to be found to get the medical images from A to B. The study management from the Cardio Research Department Maasstad Hospital, Rotterdam, of the COMPARE 60/80 HBR investigator initiated, multicenter, randomized clinical trial have chosen ClinFlows’ web based dicomdrop-solution to safely collect the angiograms from the 11 participating sites in the Netherlands enrolling 736 patients.


Cardio Research Department Maasstad Hospital, Rotterdam, the Netherlands supported by a grant of SMT (Sahajanand Medical Technologies Pvt. Ltd), a leading global developer and manufacturer of minimally invasive cardiovascular devices. The study is sponsored by the Research Maatschap Cardiologen Rotterdam Zuid, associated with the Maasstad Ziekenhuis Rotterdam, the Netherlands.


Investigator-initiated, multicenter, randomized controlled study, COMPARE 60/80 HBR: Comparison of the Supraflex Cruz 60 micron stent strut versus the Ultimaster Tansei 80 micron stent strut in a High Bleeding Risk PCI population.

Project Background:

In PCI patients at high bleeding risk (HBR), international guidelines recommend a shorter duration of dual antiplatelet therapy (DAPT). While this reduces the risk of bleeding, it may also increase the risk of stent thrombosis and ischemic events. The solution for PCI patients with HBR could be the use of ultrathin stent struts, as these may reduce ischemic events with a shorter duration of DAPT. COMPARE 60/80 HBR was initiated to investigate just this. From 2020 to 2023, under the leadership of Pieter Smits, M.D., Maasstad Ziekenhuis, Study Chairman and Principal Investigator, PCI use of the ultra-thin stent strut (60 µm) Supraflex Cruz will be compared with use of the thin strut (80 µm) Ultimaster Tansei among 736 patients with HBR. The study results may open new treatment options for PCI patients with HBR. Patients are followed for 12 months.


All angiograms of the index procedures, or any planned staged or unplanned procedures have to be sent to the Cardio Research Department in Rotterdam by the 11 participating sites. CERC Europe, Paris, France, will perform the analysis of the angiograms. The challenge was to find a very cost-effective and easy-to-use DICOM transfer tool, which provides an automated pseudonymization of DICOM tags and meets all GDPR requirements. 


For the safe transfer of the DICOM images, the Cardio research team of Maasstad Hospital has chosen ClinFlows’ web-based solution dicomdrop since the start of the COMPARE 60/80 HBR study. With just a few clicks, the eleven participating sites can use the platform to send their angiograms in DICOM format to Rotterdam in a very uncomplicated, fast, and GDPR-compliant way thanks to the integrated pseudonymization options. The application allows the coordinator to create a project within dicomdrop and to invite the participating sites to join the project. The sites can enter a case reference which is automatically inserted in the uploaded DICOM tags, to assure clear subject identification. The coordination team in Rotterdam receives a download link to collect the data, which are only stored on ClinFlows high-end, high-security servers in Europe. All uploaded data are automatically deleted from the dicomdrop-servers after ten days to minimize the risk and assure a high-end data privacy protection. All the sites have to do is to register on dicomdrop once in order to upload DICOMs within the Compare 60/80 HBR project.


From 2020 until today, more than 700 patients have already been recruited in this study and around 800 angiographies have already been transferred via dicomdrop. 

Client feedback:

“For the success of our study, it is crucial to have a reliable and stable technology for online image transmission. Furthermore, the whole process has to be simple, fast and secure. dicomdrop fulfills exactly these points. We are happy to have relied on this tool from the very beginning of the study and thus to gain new insights for PCI patients with HBR as quickly as possible,” says Ria van Vliet, Project Manager at Cardio Research Department, Maasstad Ziekenhuis.

Want to learn more about how our clients benefit from our solutions in practice? Simply get in touch via info(at) or find out here, how a leading TAVI manufacturer manages case reviews and eligibility checks to serve clients and here, how to provide clinical decision support during post-training phase.

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