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Seems pretty common sense to me that you're gonna have more people with hidden cancers coming in to get CT for phantom pains, etc and later discover they had cancer all along. That doesn't mean CT caused it. Did the study control for this?

The whole dataset seems like something hard to work with, population that needs CT scan in the first place is very biased, people don't do CT scans for fun but because there is something weird that docs can't explain already.

It's unclear to me whether you read the journal article or just the Ars article? If you're referring to the journal article that gives your assessment much more weight.

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A. Newer CT scan machines use lower radiation doses.

B. If you're getting only one scan a year you're fine and within yearly limits of radiation dosage considered acceptable.

Remember that you'll get comparable levels of radiation even if you commute through the grand central station every day.

This paper is for lack of a better word, crap. It's becoming sensational for the conclusion it makes and I'm afraid it's now going to create more harm because of that.

Someone I know got partial constipation, lack of apetite and stomach reflux. After some month of triying to fix the reflux, they discovered it was intestine cancer when the cancer was big enough to block almost all the flow.

IIUC from a sibling reply, you already used a few laxative, so perhaps a CT scan was the next step.

I had a CT scan ordered for abdominal discomfort which had been making sleep a nightmare for years.

I started taking ag1 and Metamucil and the stomach discomfort has completely gone away over a span of weeks/months.

The resulting dramatic improvement in sleep cascades to just about everything in my life and different recurring health problems keep disappearing now.

It’s crazy how many problems can be caused by apparently just not getting enough fiber.

Never ended up getting the CT scan, which probably would’ve been expensive and involve some small degree of risk.

But did those words really get through to you like an energetic photon? I think, it's quite ionic how frequently the last strand has to break before we realize, we should have been radicalized by people, not high voltage discharge events.

Why would you go to the doctor for that instead of first trying one of the many known solutions?

* a tablespoon of epsom salt * a tablespoon of mineral oil * several OTC products

Yeah, a plain old abdominal x-ray might've sufficed to diagnose that.

Or the pre-x-ray technique of abdominal palpation.

why a CT and not a X-ray? did they need to see the gestating turds in 3D?

Same. The CT is to rule out diverticulitis and in my case, since the pain was located in my lower right abdomen, appendicitis.

I was just full of shit, as usual. Now I eat salads and drink more water when I am at elevation.

lol. Well executed.

I think your logic arrow is the wrong way around. We only run screening for rare diseases when indicated, and then get things like this.

If CT scans are performed on more than 5% * (1 + false positive rate) of suspected cancer cases, having a CT scan in the history of 5% of cancer cases is entirely expected.

This is what the healthcare community claims, but they're wrong.

I took a preventative MRI run by an ML/AI company that the healthcare folks say is a bad idea. I didn't discover any hidden cancers but they did find 1-2 emerging health issues that were preventable with simple diet and lifestyle changes.

If everyone showed up to their doctor asking for preventative imaging, it would overwhelm doctors since there aren't enough resources to treat everyone who is sick. Your individual health will always be less important than the integrity of the system.

Yuck, I have recurrent kidney stones and have had many CT-scans. It seems to have become the standard procedure when you complain of abdominal pain at the ER. Years ago I remember just getting an X-ray.

What's interesting is I needed surgery to remove the most recent stones, and I've not had a CT-scan since- the urologist uses ultrasound.

On the other hand, I've had fluoroscopy.. probably worse than even CT-scans.

The comments on that article heavily criticized that portion. I don't know jack about the topic, but it really did seem like just Scott's envelope-math against the sentiment of the entire field: "this is not enough radiation to matter".

To maybe oversimplify it, cancer risk from radiation is all a stats game. The situations where you get a CT scan is either very rare (once or twice in a lifetime and often highly localized) or for a very acute issue (eg a heart attack or car accident) that is almost certainly worth the risks.

Also, ionizing radiation has a varying risks to different tissues. "Soft" tissues that have cells that divide a lot (lungs, colon, etc) are of greater risk than others. I wouldn't bat much of an eye for a CT scan on my knee, but would be more worried about a chest procedure. Again, more worried doesn't mean I wouldn't do it, as the alternative is either a much more expensive MRI, much more fuzzy echo-cardiogram, or wondering if my health is more seriously at risk.

Radiation is poorly understood in healthcare due to the LNT Model https://en.wikipedia.org/wiki/Linear_no-threshold_model.

The science is based on assumptions and extrapolation, they drew a linear plot line between rates of cancers at different levels of radiation, and then extended it down and to the left. But there is no actual experimental data showing a relationship between low dose radiation and cancer (Ironically there IS evidence that rates of overall cancers are lower in high altitude cities like Denver with more background radiation).

I’ve remodulated my phaser arrays and randomized the stochastic spectral frequencies ten times, but those Borg keep adapting!!1

Well actually let’s find out whether they do cause it or not. Patients ought to know the risks beforehand if so. The calculation as to net benefit can be done later.

People get weird when using math to calculate human lives.

Medicine: first, do no harm.

Why not use MRIs since they skip the problem entirely?

Don’t say cost or supply. That’s just because CT scans, misguidedly, have more demand. More demand for MRIs would unlock savings from scale.

> but it's a hell of a lot more than background radiation. Scary.

Not if you fly decent distances a dozen times a year or more.

It's quite hard to give bones and joints cancer. Cancer prefers dividing cells.

If cancer is also rare in those spots without a CT, that would seem to indicate a major confounding variable at play.

MRI's themselves produce no cancer risk as they're not ionizing radiation. There's SOME questions about SOME of the dyes used for SOME MRI procedures, but those are usually used in situations where the alternative is worse - so do it.

MRI doesn't use ionising radiation so it's a stretch. Most likely cause would have to be some toxic effect of the contrast dye (as opposed to any sort of ionising radiation), but no compelling evidence exists for that.

MRI's magnetic field is not strong enough. CT scans use Röntgen radiation, and that's known to cause ionization (the waves can displace electrons), which --in DNA-- potentially causes cancer.

Depends. MRI itself is safe, but they often add "contrast" which is known to cause cancer (I'm not clear on if there is more than one choice for contrast though, or if they all cause cancer). Of course contrast is mostly used when they looking at a something - likely a tumor that might or might not be cancer to decide how to treat it - in that case does it matter that your long term cancer prospects go up when without it your short term prospects are not good.

You're safe

No, not necessarily.

CT scans are likely overused; my spouse has several chronic conditions and after receiving dozens a year for a while, we started asking if a CT was clinically indicated, or just precautionary. Mostly the response is "just in case". I wish EMRs did a better job of highlighting how many CTs someone's had recently for this sort of decision making.

There've also long been problems with kids getting unnecessarily high adult doses of radiation. My dad's a peds radiologist and was heavily involved in the founding of https://www.imagegently.org/.

My kid needed an abdominal ultrasound in the ER, but the ultrasonographer had gone home for the night. They did a CT instead, despite my concerns. CT missed the problem, which festered for several more years before being discovered during our next ER visit … on an ultrasound.

The folks round these parts that transfuse the blood of young healthy people to boost their lifespan are probably having a regular CT scan too.

I have a friend who went to an allergist last week for sinus issues. They did a CT scan within 5 minutes of coming into the office.

The "almost certainly" that you brush off is the entire point of the calculation. Is it 95% certain or 99.5% certain? The exact balance between benefit and risk in medical procedures is exactly how it is determined when to use them in the standard of care.

My first MRI about 30 years ago they did a precautionary CAT scan of my head because I had worked in machine shop (the place I worked had a machine shop and I used it for small personal projects), dunno if they do that anymore, but I was told ferrous bits in eyes had led to disastrous results for at least one patient.

In most cases instead of CT scan one could do the same diagnosis with MRI scan, which is only a bit more expensive.

Yeah, no. A doctor that I had a feeling wasn't paying too close attention to what I was saying ordered a pelvic/abdominal CT with and without contrast, ~30-40 mSv. Nothing turned up on the scans. When I went back he said "nothing's wrong" and, confused, I described my symptoms again. He just said "Oh! You need physical therapy."

Two weeks of physical therapy and I was fine.

At the time I was mad about the money, now I'm just thinking "what a dumb way to (maybe) get gut cancer."

I was young. I thought I was scheduled for an MRI like the one I had for my sinuses. I didn't even know what a was CT at the time.

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Theoretically causing a lot of cancers in modelling studies.

In practice a CT machine is also a much better workhorse for innumerable tasks that are very hard to effectively investigate with an MR machine, as MR imaging takes significantly more time, and requires more technical knowhow among the medical staff involved.

Is the load factor of those Japanese machines similar to those used in the US? Isn't life expectancy multifactorial?