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Comment by Shinkei | Hacker News Reader

CT is a great screening exam because it is cheap, quick and more readily available. MRI is much more specific in diagnosing problems in the brain and has a lot more 'features' that can be added to aid in diagnosis. So generally, everyone gets a CT and then moves on to an MRI if there is an abnormality... or if they fail to find an abnormality when the clinical exam remains abnormal/severe. There are a lot of exceptions... like in little kids, you should always avoid radiation when possible and people will go straight to MRI.

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Why is there such a big difference in patient price between a CT and MRI scan?

My doctor told me to have a CT scan done but I am worried about the radiation. I feel that if an MRI was cheaper, then I would have been prescribed an MRI.

Ask them about the radiation dose in banana-equivalent, then be less worried.

You're confusing CT scans with conventional x-ray images. CT scans deliver the radiation equivalent of hundreds of conventional x-ray images. The radiation dose is high enough to epidemiologically significant (meaning higher cancer rates in people who have been scanned, especially children).

Believe me, I'm not confusing them - I just think it's significantly less risky than the parent does. And yes, there can be higher cancer rates in people who have a _lot_ of CT scans done e.g. because of a serious illness.

I'd rather get that back to me as a percentage compared to a Phone Booth filled with nuclear waste (but only 75% of the way up) while standing 13.43 meters away with the humidity levels at 95%.

The MRI scanner requires more precautions and safeguards (being built around a 1+ tesla magnet), and acquiring images takes more time, thus more human resources.

Edit: to illustrate ris' point (the sibling comment), check this XKCD chart, linked in the article: http://xkcd.com/radiation/

The equipment and maintenance is much more expensive for MRI. The liquid helium bill alone for an MRI machine is not something you want to pay for.

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