Surely, each of us has visited a hospital for medical check-ups at least a few times. Previously, I used to think that the X-ray and CT images I received were copies, and the original files that doctors kept would be in a regular image format like bitmap, jpeg, etc., accompanied by a patient information management program with the attached files being the captured images. However, my perspective changed when I had the opportunity to participate in a project related to the medical field, specifically in DICOM image processing. The above thinking became outdated.

By calling them outdated, I mean that the conventional practice of managing image and patient information, as I had previously thought, existed prior to 1985, before the term DICOM introduced. DICOM was born because the old storage method had many limitations. Different imaging devices had different standards, making it impossible to interact with other databases. For example, if a doctor wanted to reuse images obtained from a CT scanner for analysis and treatment planning, they could only be decoded by the specific CT scanner used, and each CT device had a different method of encoding and decoding images.

Due to these limitations, in 1985, the DICOM (Digital Imaging and Communications in Medicine) image standard was introduced with the purpose of standardizing image information for easy sharing of image data generated from any type of device or manufacturer. Up until now, after many upgrades, the DICOM standard is being used worldwide to store and transmit information between different medical devices.

For doctors, they can access images and related medical reports more easily, enabling them to make diagnoses from anywhere in the world. I would like to provide the following example for comparison.

Figure 1: Example of past medical image storage

Figure 1: Example of past medical image storage

Figure 2: Example of using dicom image

As seen in Figure 2, the use of DICOM images has overcome the issue of managing discrete information. Hospitals and devices can interact with each other to share image information.

Regarding the structure of DICOM, it is as Figure 3

Figure 3: Dicom format 

Figure 4: Example of reading an dicom image

Using a Micro DICOM viewer to open a DICOM file, as shown in Figure 4, you will see:

  • On the left side, the image obtained from the CT scanner.
  • On the right side, the attached information.
  • The information with codes (0002, ...) represents the header information.
  • The information from (0008, ...) downwards represents the Data Elements.
  • The pair of numbers in parentheses (..., ...) is called the Tag ID.

Therefore, inside a DICOM image, in addition to the images obtained from imaging devices, there is also information related to the patient, history of the image, image format, imaging device, etc. Each piece of information is identified by Tag IDs, as defined by the NEMA organization.

So far, you can have a basic understanding of DICOM images and how they work. For more details, please refer to this page, which is the official DICOM standard website.


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