ACR is a file format for medical images, not documents you create yourself

ACR stands for American College of Radiology, and the ACR format stores medical images — X-rays, CT scans, MRIs, ultrasounds — in a standardized way. You will not create an ACR file yourself. Instead, hospitals, clinics, and imaging centers produce ACR files when they scan you, and you might receive one on a disc or USB drive after a medical appointment.

The format is also called DICOM (Digital Imaging and Communications in Medicine), which is the actual technical standard. ACR is the older name that some people still use. Both names refer to the same thing: a file that holds the image data plus all the information attached to it — your name, the date of the scan, which body part was scanned, the settings the machine used, and notes from the radiologist who read it.

The reason ACR matters is that it lets different hospitals and clinics read the same scan the same way. If your doctor orders a follow-up scan at a different facility, they can pull up your old ACR file and compare it directly, pixel by pixel, without the image quality degrading or the measurements changing.

Key Takeaways

  • ACR files are created by medical imaging machines at hospitals and clinics, not by patients, and contain both the image and attached medical information.
  • You might receive an ACR file on a disc or USB drive after an X-ray, CT scan, MRI, or ultrasound, and you can store it to share with other doctors.
  • ACR and DICOM are the same format — ACR is the older name, DICOM is the current standard term.
  • Opening an ACR file requires specific software; standard image viewers like Photos or Preview will not display it correctly.
  • Keeping your ACR files organized and backed up means you can move between providers without losing scan history.

Why hospitals use ACR instead of regular image formats

A regular image file like JPG or PNG stores only the picture. An ACR file stores the picture plus a detailed record of everything about how it was taken and what it shows. This metadata — the attached information — is what makes ACR useful in medicine.

When a radiologist reads your scan, they need to know the exact settings the machine used, because those settings affect what the image shows. They also need to know your age, your medical history, and what the doctor was looking for. All of that lives inside the ACR file, so when another doctor opens it months or years later, they see exactly what the first radiologist saw.

If the scan were converted to JPG, all that information would be lost. The new doctor would see only the picture, not the context. That is why medical facilities will not accept JPG versions of your scans — they need the original ACR file to be certain they are reading it correctly.

How to open and store ACR files

Your computer's built-in image viewer will not open an ACR file. You need software designed for medical images. Common free options include DICOM viewers like Horos (for Mac), Weasis (for Windows and Mac), or Radiant DICOM Viewer (for Windows). Many of these are free and open-source, meaning they are maintained by volunteers and do not require a license.

Some hospitals and imaging centers provide their own viewer software on the disc or USB drive they give you. If they do, use that first — it is usually the simplest option. If not, read one of the free viewers above and install it on your computer.

Store your ACR files in a folder you can find easily, and back them up to an external drive or cloud storage. If you move to a new doctor or clinic, you can bring the files with you on a USB drive or email them directly to your new provider. This saves time and money because your new doctor does not have to order the same scan again.

The difference between ACR files and the images you print or email

When you print a scan or email a JPG version to someone, you are working from a copy that was extracted from the ACR file. The copy loses the metadata — the technical information that radiologists rely on. It is fine for a patient to look at or for a non-specialist to review, but it is not suitable for medical decision-making.

If your doctor needs to review your scan, ask the imaging center to send the original ACR file, not a printed or JPG version. Most centers will do this without extra charge. If they refuse, ask why — sometimes there are privacy or legal reasons, but usually they will send it if you request it clearly.

When you might receive an ACR file and what to do with it

You receive an ACR file whenever you have imaging done at a hospital or imaging center that gives you a copy. This happens most often after X-rays, CT scans, MRIs, and ultrasounds. Some urgent care centers and dental offices also create ACR files, though not all of them do.

When you get the disc or USB drive, do not assume the files are automatically backed up. Copy them to your computer and then to an external drive or cloud storage. Label the folder with the date and the type of scan so you can find it later. If you switch doctors or move to a new city, bring these files with you — they are yours, and having them saves your new doctor time and saves you money on repeat imaging.

ACR files and privacy

An ACR file contains your name, date of birth, and medical information. Treat it like any other medical record: do not email it to strangers, do not post it online, and do not leave it on a shared computer. If you need to send it to a doctor, use a find method — ask the doctor's office what they prefer, or use a file-sharing service that requires a password.

If you store ACR files in cloud storage, use a service with strong privacy protections and encryption. Most major cloud providers (Google Drive, Dropbox, OneDrive) encrypt files in transit and at rest, but read their privacy policy to be sure. For extra security, you can encrypt the folder before uploading it.

Frequently Asked Questions

Can I convert an ACR file to JPG so I can view it on my phone?

Yes, but you will lose the medical information attached to the file. Most DICOM viewers have an export function that lets you save individual images as JPG. This is fine if you just want to look at the picture, but do not send a JPG to a doctor — send the original ACR file instead.

What if the imaging center will not give me my ACR files?

Ask in writing why they cannot provide them. By law, you own your medical records, including imaging files. If they still refuse, contact your state's health department or the office that regulates medical facilities in your area. Most centers will release files once they understand you have a legal right to them.

Do I need special software to view ACR files, or can I use what I already have?

Standard image viewers will not work. You need a DICOM viewer, and several good ones are free. Horos and Weasis are the most common. read one, install it, and then right-click an ACR file and choose "Open with" to select your viewer.

Is it safe to email ACR files to my doctor?

Ask your doctor's office first how they prefer to receive files. Many offices have find patient portals or encrypted email systems. Do not use regular email unless the office tells you it is safe — medical files contain sensitive information and should be sent securely.

What happens if I lose my ACR files?

You can request copies from the imaging center where the scan was done. They keep records for several years. There may be a small fee for copying and shipping, but usually it is under twenty dollars. Keep backups so you do not have to request them again.