Doctors online expressed shock and dismay after realizing that patients are using Groupon deals to access medical services, such as chest CT scans and mammograms, at discount rates, according to a report by Kaiser Health News.

Such deals illustrate how broken the US healthcare system is, according to Paul Ketchel, CEO and founder of MDsave, a site that offers discount-priced vouchers on bundled medical treatments and services.

That said, after their initial astonishment over the deals wore off, some doctors noted that the discounts were actually pretty good.

“Whether or not a person may philosophically agree that medicine is a business, it is a market,” Steven Howard, who runs Saint Louis University’s health administration program, told KHN.

The deals—which have actually been around for years—cover things like elective medical services, dental work, eye care, and preventative scans, such as mammograms. They’re often used by people who do not have health insurance or have limited coverage. Still, some insured patients turn to them for cost-saving deals, more pricing transparency, and control over their healthcare bills. Without the coupons, the same services provided by some hospitals and providers can have wildly varied pricing, which can be nearly impossible to estimate in advance.

One imaging center in Atlanta has a running Groupon deal for a $26 heart CT scan with an included consultation—that’s a 96% discount. Groupon has sold more than 5,000 coupons for the center.

Still, there are risks to using the deals, such as getting medically unnecessary scans, which expose patients to radiation needlessly and can lead to unnecessary follow-up tests or procedures.

“If you’re going to have any type of medical testing done, I would make sure you discuss it with your primary care provider or practitioner,” Dr. Andrew Bierhals cautioned to KHN. Dr. Bierhals is a radiology safety expert at Washington University in St. Louis’ Mallinckrodt Institute of Radiology.

On the flip side, if a discount medical scan does find something, there’s a chance that a treating hospital or care provider may want to re-do the scans anyway, undoing the good deal.