What File Formats ACR Can Open and Save

ACR supports DICOM files, which is the standard format for medical images

ACR (American College of Radiology) is a viewer for DICOM files — the format used across hospitals, clinics, and imaging centers to store X-rays, CT scans, MRIs, ultrasounds, and other medical images. If you have a medical image file on your computer and need to open it, ACR can read it if that file is in DICOM format.

DICOM stands for Digital Imaging and Communications in Medicine. It is not a format you choose when you take a photo on your phone — it is what radiologists and imaging technicians use when they need to preserve all the technical information about a scan: the exact pixel values, the patient's name and ID, the date and time, the equipment settings, and notes from the radiologist. ACR reads all of that information and displays the image on your screen.

ACR can also open some related formats that hospitals use, including JPEG and PNG files if they have been exported from DICOM, and it can save images in multiple formats depending on what you need to do with them next.

Key Takeaways

ACR opens DICOM files, which is the standard medical imaging format used by hospitals and imaging centers worldwide.
You can save images from ACR as JPEG, PNG, BMP, or TIFF files if you need to share them outside a medical system.
ACR preserves all the technical data embedded in a DICOM file, including patient information and scan settings, when you open it.
If your medical image file has a .dcm extension, ACR will open it; if it has another extension, you may need to check with your doctor's office whether it is actually a DICOM file.

DICOM is the only format ACR is designed to read

ACR's main job is opening DICOM files. Every medical imaging device — whether it is a CT scanner, MRI machine, X-ray unit, or ultrasound system — saves its output as DICOM. This is true in the United States and in most countries worldwide. When you get a scan at a hospital or imaging center and they give you a disc or a file to take home, that file is almost always DICOM.

DICOM files usually have a .dcm file extension, though sometimes they have no extension at all or are named with just numbers. If you are not sure whether a file is DICOM, you can try opening it in ACR — if ACR recognizes it, it is DICOM. If ACR cannot open it, the file is in a different format.

ACR will not open common photo formats like JPG, PNG, or GIF directly. It also will not open PDF files, even if a PDF contains a medical image. If your medical image is in one of those formats, it came from a DICOM file that was already converted by someone else — usually your doctor's office or imaging center exported it that way for easier sharing.

Saving and exporting images from ACR

Once you open a DICOM file in ACR, you can save the image in several other formats. The most common are JPEG, PNG, BMP, and TIFF. You would do this if you need to share the image with someone who does not have medical imaging software, or if you want to include it in a document or email.

When you save a DICOM image as JPEG or PNG, ACR converts it to a regular picture file. This means the technical medical data — the patient ID, the scan date, the equipment settings — is lost. You are left with just the visual image. This is fine if you only need to show someone what the scan looks like, but it is not suitable if you need to preserve the complete medical record.

If you need to keep the DICOM file itself intact and just want to share it, you can copy the .dcm file directly without opening it in ACR. Many doctors' offices can also send DICOM files through secure email or patient portals.

Why hospitals use DICOM instead of regular image formats

DICOM exists because medical images need to carry information that a regular photo format cannot store. A chest X-ray is not just a picture — it is a picture plus the patient's name, medical record number, the date and time of the scan, which body part was imaged, the equipment that took the image, and often notes from the radiologist who read it.

DICOM also preserves the full range of gray values in a medical image. A regular JPEG compresses the image to make the file smaller, which can lose detail that a radiologist needs to see. DICOM keeps all the original data, which is why radiologists use it for diagnosis.

This is also why ACR is free — it is built to read the standard format that the medical industry already uses, not to compete with photo editing software or create a new standard.

Opening DICOM files from your doctor

If your doctor gave you a disc with medical images, or sent you a file download link, that file is almost certainly DICOM. You can open it in ACR by dragging the file into the ACR window, or by using the File menu and selecting Open.

If the file has a .dcm extension, ACR will recognize it immediately. If the file has no extension or an unfamiliar extension, ACR may still be able to open it — DICOM files do not always have the .dcm label. Try opening it anyway.

If ACR cannot open the file, ask your doctor's office what format they sent. They may have sent a JPEG or PDF by mistake, or the file may be corrupted. They can usually resend it in the correct format or help you open it with their own software.

Converting DICOM files to other formats

If you need to convert a DICOM file to JPEG, PNG, or another format, ACR can do this. Open the DICOM file, then use File > Export or Save As and choose your desired format. ACR will save the image as a regular picture file that you can open in any photo viewer or editor.

Keep in mind that this conversion removes all the medical metadata. The resulting file is just an image — it no longer contains the patient information, scan date, or technical details. This is usually fine for personal use or sharing with family, but it is not suitable for medical records or if you need to send the image back to a healthcare provider.

If you need to share medical images with another doctor or hospital, ask your current provider to send the original DICOM file instead of converting it. This preserves all the information they may need to review your care.

Frequently Asked Questions

Can ACR open PDF files with medical images in them?

No. ACR only reads DICOM format. If your doctor sent you a PDF, you need to open it with a PDF reader like Adobe Reader. If you need the image in DICOM format, contact your doctor's office and ask them to send the original file instead.

What if my medical image file has no extension?

Try opening it in ACR anyway. DICOM files do not always have a .dcm extension — some are named with just numbers or have no extension at all. If ACR can read it, it is DICOM. If ACR cannot open it, the file may be in a different format or corrupted.

Can I edit a DICOM file in ACR and save it as DICOM again?

ACR is a viewer, not an editor. You can adjust brightness and contrast while viewing, but you cannot make permanent changes and save them back to the DICOM file. If you need to edit medical images, you need specialized medical imaging software, which your doctor's office or hospital would use.

Is it safe to convert my DICOM files to JPEG for storage?

JPEG conversion loses some image detail and removes all medical metadata, so it is not suitable as your primary medical record. Keep the original DICOM files if your doctor gave them to you. JPEG conversion is fine only if you want a copy for personal reference or to share with family.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.