They could offer you a download link, that is valid for 10 days. Or since storage is cheap, stays valid.

But why change a running system (and I have an external USB DVD device).

Depending on the jurisdiction, the minimum required storage time for medical data varies - but it needs to be kept around usually. Patients can, within that time frame, request that data to be provided, but may be required to pay some fee to cover the material costs. In my jurisdiction, this time frame is 10 years, and radiology data is usually provided as a paper slip with a link and password, valid for 1-2 years, or DVDs on request.

Keeping that data around and managing requests for it is a part of why older physicians are so keen to sell their practices to younger doctors here - they can pass on the duty of keeping up with storing the data that way.

FWIW, I'm in a jurisdiction with a 10 year retention requirement, and also have had no issues getting imaging data from beyond that (on DVD, of course - one department even had a side hustle selling external DVD drives for $50 on the side; they even offered to drop the files onto a USB drive for free).

Offering USB flash versions would make sense, too, given the low cost presently. There's probably a market for write-once flash drives.

If it stays valid that's a security nightmare

People are very good as securing physical items. They are awful at securing files.

A dvd or maybe an SD card or USB stick is a much better approach.

There is some utility unique to the dvd imo. It seems way more secure to me if another practitioner is just being handed a dvd direct from the imaging dept by the patient, compared to an emailed link that could be cloned in phishing attempts hospitals get. Anyone who expects to look at these images probably has a disk drive. It is kind of better than a thumb drive because its cheaper to make for the hospital but also can sit in a folder with other paperwork nicer than any thumb drive.

When I was 15 I discovered that my local doctor lost all of my medical records. Poof, all gone. Whoops, next patient please. My last doctor no longer had a copy of my files, either.

I had to receive all of my vaccinations again over two sessions before attending public school.

Now instead of losing a yellow folder, a system will lose 1 million people’s records all at once.

Aren’t school vaccines registered with the state? Given how many parents cannot keep records, I am surprised the solution would be “get them again”.

Offsite backup needs to always be the answer. Fires have always been a concern in any human situation. Plus lots of other accidents.

Of course the real hard part is how do you mark a record as do not restore anymore. In a medical context this isn't much a problem, but in other cases it is an issue.

did you by chance undergo any operation you never consented too?

It is worth noting that a lot of people DO own DVD and Blu-Ray drives still - they are just stuck inside of gaming consoles.

Game consoles are starting to come without optical drives.

It makes complete sense. It's literally pennies for them, esp. when bought in bulk, it's read-only (more or less), and most importantly it absolves them of any responsibility regarding handing you some very sensitive personal data. No credentials, cloud service, hacking, leak, etc etc. They hand you a physical object and that's it. It's your problem now.

A pendrive would work almost as well but too many people likely would accidentally reformat them, add data and mix them up, claim they got a virus from them (which they maybe did, when their 8yo nephew clicked everything looking for big boobs online, not because of the doctor. But now the doctor has to prove the virus on the pendrive was added later? Just hand the patient a DVD really).