CT scans could cause 5% of cancers, study finds; experts note uncertainty
arstechnica.com125 points by pseudolus 4 days ago
125 points by pseudolus 4 days ago
Impossible to draw any conclusions from such a convoluted and problematic model. No mention of how they determined patients were unique, or whether multiple scans were counted for a single patient. No mention of patient data - seems that covariates were estimated, leading to greater uncertainty. For example, we have no idea if any of these patients already had cancer before getting a scan. And of course, this entire model is incapable of answering the question that patients actually care about: not "will I get cancer from this?" but "will this scan more likely increase or decrease my lifespan and/or quality of life?".
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?
> Did the study control for this?
No, because that's not how the study worked, i.e. it wasn't actually tallying cancer rates from people who had CTs. It basically just looked at the amount of radiation that a CT scan gives a person, and then extrapolated the cancer that would be expected from that radiation dose based on other data we have of e.g. people exposed to radiation in their jobs, and nuclear fallout occurrences.
Previous studies I've read did account for this, and put the number at about 3%. That said CT manufacturers have been working on a bunch of technology to make this better, either by doing a better job at not aiming at sensitive areas or by reducing the amount of radiation needed to get the same resolution in the images.
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.
I went to the doctor complaining of constipation. He sent me for a CT scan which showed that I was literally full of shit. The prescription was for a large dose of MiraLax. Now I wonder if the risk of the CT scan was really justified given that plenty of people already tell me that for free and without radiation.
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.
> B. If you're getting only one scan a year you're fine and within yearly limits of radiation dosage considered acceptable.
But doesn't it make a difference if that "acceptable yearly limit" is spread out throughout the year as opposed to a few minutes of CT scan session?
I had a CT of my pelvis and abdomen recently and worked out it was equivalent to about 5 years worth of background radiation.
The dose required is actually quite a lot higher than typical comparisons to eg chest X-rays and the like
> Remember that you'll get comparable levels of radiation even if you commute through the grand central station every day.
Gemini says this:
> A single typical CT scan delivers a dose that is roughly 1,000 to over 5,000 times higher than the dose you'd get from spending a few hours in Grand Central Terminal.
Where did you get that from?
If the hallucination machine can cite a source, check and cite that for facts, but don't cite the hallucination machine.
Weird you don't have this requirement for the OP spewing his urban myths above.
Human hallucinations are natural.
Machine hallucinations are avoidable.
Was it hallucinating here, or are the commenters hallucinating? What OP is saying is just not true. A CT scan and normal daily commute in Grand Central station are NOT comparable in terms of radiation received. Somehow this is controversial because an AI said it?
The machine appears to have hallucinated the incomparable comparison, instead of a human.
(And I'm not picking on the machine at all here. I use it all the time. At first, I used to treat it like an idiot intern that shouldn't have been hired at all: Creative and full of spirit, but untrustworthy and all ideas need to be filtered. But lately, it's more like an decent apprentice who has a hangover and isn't thinking straight today. The machine has been getting better as time presses on, but it still goes rather aloof from time to time.)
Did you actually discredit someone or have you not properly considered your units in this response?
Commute through the Grand Central station everyday is certainly not a few hours.
And people don't tend to get a CT scan very frequently so the timeline here is massive.
In your opinion how many hours spent in Grand Central station equal the radiation received from a CT scan?
Somewhere between 7 and 700 days.
CT Scan: 10-1000 mrem
Grand Central Station: 525 mrem / yr
So OP's statement is true for people who live IN the station.
It's roughly 40 min per workday over a typical year. That's a bit high but not unreasonably so.
That would amount to 10 mrem of radiation per year. I don't believe this is a realistic estimate for a CT scan though. From epa.gov [1]:
- Head CT: 2.0 mSv (200 mrem)
- Chest CT: 8.0 mSv (800 mrem)
- Abdomen CT: 10 mSv (1,000 mrem)
- Pelvis CT: 10 mSv (1,000 mrem)
So for a head CT, one would need to spend more than 13 hours per workday in the station. OP was off at least an order of magnitude.
https://www.epa.gov/radiation/frequent-questions-radiation-m...