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When you have an MRI, CT, X-ray, or mammogram, the images are saved as DICOM files, the international format used in radiology worldwide. If you want an independent radiology second opinion, these are the files you will need, not a screenshot or a paper printout. This guide explains, in plain language, what DICOM is, why it matters, and exactly how to get your DICOM files from the hospital or radiology practice so a specialist can review your scan properly.
What is DICOM?
DICOM stands for Digital Imaging and Communications in Medicine. It is the standard that defines how medical images are formatted, stored, and exchanged between scanners, hospital systems, and viewing software. The standard is maintained by the National Electrical Manufacturers Association (NEMA), and it is the reason a scan taken on one manufacturer’s machine can be opened on another system anywhere in the world.
A DICOM file is more than a picture. Alongside the image, it carries structured information: the imaging settings, the body region, the date, and technical detail about how the scan was acquired. This is why your images are not saved as ordinary JPEG or PNG files. A photograph of your screen or a single exported image loses most of this data, and with it much of what a radiologist needs to give a reliable reading.
Inside a hospital, DICOM files live on a system called a PACS (Picture Archiving and Communication System). When your doctor reviews your scan, they are looking at the full DICOM dataset on a calibrated screen, scrolling through dozens or hundreds of image slices rather than viewing one flat picture.
Why your scan files matter for a second opinion
A radiology second opinion is only as good as the data it is based on. When a subspecialist reviews your case, they want the complete DICOM files so they can scroll through every slice, adjust the contrast, and measure findings exactly as the original radiologist did. Sending a phone photo of one image, or only the written report, means the second reader is working with a fraction of the information.
Research summarised in our guide «What Is a Radiology Second Opinion? A Complete Guide» indicates that an independent subspecialty review of complex imaging changes the interpretation or the recommended management in a meaningful share of cases, with reported rates varying widely by modality and clinical setting. None of this is possible without the original scan files. This is also why, before any operation, many patients choose to have the underlying images re-read, as discussed in «Second Opinion Before Surgery: Why It Could Save Your Life».
The World Health Organization has highlighted that correct and timely interpretation of imaging is central to patient safety, and that the secure remote transmission of diagnostic images can extend access to expert reading (WHO, Strengthening medical imaging). Your DICOM files are what make that remote expert reading possible.
How to get your DICOM files
You have a right to a copy of your own medical images. In most countries this is straightforward, and reputable imaging providers are used to the request.
In Switzerland and across the DACH region, the Federal Act on Data Protection (DSG) gives patients the right to obtain copies of their own data, including imaging (Swiss Federal Data Protection and Information Commissioner). In the European Union, Article 15 of the GDPR provides a comparable right of access (GDPR Article 15). In practice, you simply contact the radiology department or practice that performed the scan and ask for a copy of your images in DICOM format.
Most providers deliver your scan files in one of three ways. You may receive a CD or DVD containing the DICOM files, often with a small viewer program included on the disc. You may be given a USB stick, which is increasingly common as fewer computers have disc drives. Or you may be offered a secure patient-portal download, where you log in and download the DICOM files directly to your own device. When you make the request, ask specifically for the images in DICOM format, and confirm whether a written report can be included as well.
If you only have a CD or a paper printout
If your clinic only provides a disc, that is perfectly normal, and the files on it are exactly what a second-opinion service needs. You do not have to mail the physical disc; you can copy the DICOM files from the CD onto your computer and upload them. A paper printout or a report alone, however, is not enough for a full image review. If that is all you currently hold, request the underlying DICOM files before arranging a second opinion.
How to open and check your DICOM files
You do not need any special software simply to send your files onward, but many patients like to see what they have. Because DICOM files are not standard pictures, a normal photo viewer will not open them. A free DICOM viewer will. Several reputable free options exist for Windows and Mac, and patient-facing resources such as RadiologyInfo.org, run by the Radiological Society of North America, explain medical imaging for patients in accessible terms.
If you open the files yourself, the goal is only to confirm that the scan is present and readable, for example that the folder contains image data rather than being empty. Interpreting what the images show is the radiologist’s job, and viewing your own scan on a home computer is not a substitute for an expert reading on a calibrated diagnostic display.
Sending your DICOM files for a radiology second opinion
Once you have your DICOM files, sending them for review is the easy part. A secure online service lets you upload the files directly, which is faster and safer than posting a disc through the mail. Look for encrypted upload and delivery, and for compliance with recognised data-protection standards such as the Swiss DSG and the EU GDPR.
Because the files travel as data rather than as a physical object, a specialist anywhere can receive them, match your case to the right subspecialty, and return a clear written report. If you are unsure which scan files to send, or whether you have the complete set, it is always reasonable to ask the service before you upload.
⚠ Key Considerations
The full DICOM files, not a screenshot or report alone, are what a radiologist needs for a reliable second reading.
You have a right to a copy of your own images; in Switzerland this is grounded in the DSG, and in the EU in GDPR Article 15.
A second opinion is an additional expert perspective. In many cases it confirms the original reading, and it does not imply that the first radiologist was wrong.
Viewing your own DICOM files at home can be reassuring, but it is not a diagnosis. Always discuss findings with a qualified doctor.
Frequently asked questions
What does DICOM stand for?
DICOM stands for Digital Imaging and Communications in Medicine. It is the international standard, maintained by NEMA, that defines how medical images such as MRI, CT, and X-ray are stored and exchanged.
How do I get my DICOM files from the hospital or radiology practice?
Contact the department that performed your scan and ask for a copy of your images in DICOM format. You will usually receive them on a CD or DVD, on a USB stick, or as a secure patient-portal download. You have a right to a copy of your own imaging data.
Can I open DICOM files on a normal computer?
Not with a standard photo viewer, because DICOM files are not ordinary pictures. You can open them with a free DICOM viewer available for Windows or Mac. You do not, however, need to open the files in order to send them on for a second opinion.
Do I need to open my DICOM files before sending them for a second opinion?
No. You can upload the DICOM files exactly as you received them. The radiologist reviewing your case will open and analyse them on professional diagnostic software.
Is it safe to upload my DICOM files online?
With a reputable service, yes. Look for end-to-end encryption and compliance with data-protection standards such as the Swiss DSG and the EU GDPR. Secure online upload is generally faster and safer than mailing a physical disc.
Conclusion
Understanding what DICOM is takes the mystery out of your scan files and puts you in control of your own imaging. Your DICOM files are the complete record of your scan, you have a right to a copy, and getting them is usually a simple request to the clinic that performed the examination. With those files in hand, an independent radiology second opinion is only an upload away.
If you have questions about your scan, speak with a specialist radiologist.
Sources
DICOM Standard, National Electrical Manufacturers Association (NEMA)
World Health Organization, Strengthening medical imaging
World Health Organization, Diagnostics
RadiologyInfo.org, Radiological Society of North America
Swiss Federal Data Protection and Information Commissioner (DSG)
EU General Data Protection Regulation, Article 15
This article is for general information and patient education. It does not constitute medical advice and is not a substitute for diagnosis or interpretation by a qualified doctor. A radiology second opinion is an additional expert perspective and does not imply that an earlier reading was incorrect. Always discuss your scan and report with your treating physician.