19 ms·

We Are Giving Ourselves Cancer

260 points by uladzislau 13y ago

DenisM 13y ago
>A single CT scan exposes a patient to the amount of radiation that epidemiologic evidence shows can be cancer-causing That does not look right to me. A single CT scan is 2-7 millisieverts, and exposures under 13 can not be linked to health effects - look for UNSCEAR in http://en.m.wikipedia.org/wiki/Sievert http://en.m.wikipedia.org/wiki/Sievert If you do the math by ICRP formulae, you end up with increase chance of cancer of 1 in 2600 over the next 20 years from a single 7ms CT scan today. This compares favorably with "natural" risk that is 1 in 10 without any extra exposure above background radiation. Now if you do a scan every year for the next 20 years your chances go up to 1 in 130. So there is something to worry about, but article overstates the cause.
- Zigurd 13y ago
  > Now if you do a scan every year for the next 20 years your chances go up to 1 in 130 Unless the article is wrong about the number of CT scans many people are getting, that's going to result is a huge number of avoidable cancer cases.
  - 001sky 13y ago
    The distribution of these cases is likely to skew towards the Elderly and over 50 demographic. I'd be curious to see the impact of this on the analysis.
  - pedalpete 13y ago
    I'm not very good at math, but I'm reading that as a 0.7% increase in your chance of getting cancer. From 'Physics for Future Presidents', they say it is commonly accepted that we have a 20% chance of DYING from cancer before calculating for outside influences. http://books.google.com.au/books?id=6DBnS2g-KrQC&pg=PA98&lpg=PA98&dq=physics+for+future+presidents+cancer&source=bl&ots=_0qSSAxozw&sig=mGZEYJPaciupf-a7ZUCS_HIEhac&hl=en&sa=X&ei=XZvtUqnqNsmZiQfq8IDQAQ&ved=0CCYQ6AEwAA#v=onepage&q=physics%20for%20future%20presidents%20cancer&f=false http://books.google.com.au/books?id=6DBnS2g-KrQC&pg=PA98&lpg... Let's say the average person does not get a CT scan every year for 20 years, but rather gets 5 scans over their lifetime. Those scans may detect an early stage of cancer, therefore saving the persons life. They're risk of dying from cancer is approximately 20.2%. I suggest with the CT scan, their still coming out on top.
    - novaleaf 13y ago
      that's an extra 0.7% for you. For a population of 300m (about the pop of the usa) that'd be an extra 2.1m people getting cancer.
      - monkeyspaw 13y ago
        Any idea what the error bars are on that .7% figure?
- deleted 13y ago
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- pbreit 13y ago
  The Wikipedia article lists a full body CT scan at 10-30 mSv.
  - DenisM 13y ago
    I was going off the list http://en.m.wikipedia.org/wiki/X-ray_computed_tomography http://en.m.wikipedia.org/wiki/X-ray_computed_tomography and in haste I stopped after head and chest. You are right, I should have gone further down to the full-body as well. Thanks for that. Incidentally, this is exactly why I included the numbers - so you can check them, and why I don't like the headline article - no numbers and no references, so there is nothing to check, only vaguely scary claims.
    - rdl 13y ago
      Newer machines are at least reducing the radiation. This is due to better compute power and to better sensors (essentially a mineral which converts x-rays into flashes of light which then get captured by a photodiode). It's been huge in dental x-rays, going from film to CR/DR (although dental isn't huge, it's routine, and involves a large patient population including kids.) We probably will be <5 mSv for whole-body pretty soon. Ultimately there's no reason it can't be well under 1 mSv. Fluoroscopy on the other hand is easily 50 mSv/min and multi-hour procedures (!!!). People get acute effects from that.
- redschell 13y ago
  The American Association of Physicists in Medicine seems to have your back: http://www.usnews.com/science/articles/2012/01/17/phsycists-fear-of-diagnostic-radiation-is-overblown http://www.usnews.com/science/articles/2012/01/17/phsycists-... A full-body CT scan results in 12 mSv; a mammogram 0.13 mSv—a hundred times less. The risks from these procedures, according to AAPM, are too low to have been determined reliably, and may be "nonexistent." Looks like this debate has been going on for a while now.
  - johnjm 13y ago
    Here[1] is a very recent study from Austrialia which concludes CT scans during childhood and adolescent increase the risk of cancer and should be avoided where possible. [1] http://www.bmj.com/content/346/bmj.f2360 http://www.bmj.com/content/346/bmj.f2360
- yetanotherphd 13y ago
  >If you do the math by ICRP formulae, you end up with increase chance of cancer of 1 in 2600 over the next 20 years from a single 7ms CT scan today. This compares favorably with "natural" risk that is 1 in 10 without any extra exposure above background radiation. But that is a meaningless comparison. The doctor should be comparing this additional risk, to the benefit of the scan. The "natural" risk of developing cancer is totally irrelevant to the cost-benefit analysis.
  - carbocation 13y ago
    Because we operate in likelihood ratios, the unexposed risk is important so the risk can be computed (at least, in theory; in practice, people go more by indication than by formal risk prob/benefit prob).
    - yetanotherphd 13y ago
      That still makes no sense. If I want to know whether to do a CT scan, the only relevant fact is the increase in probability (in an absolute sense) of cancer that it causes. It seems like either you, or the entire field of medicine, is obfuscating this basic fact using some field-specific concepts. EDIT: It seems like you are referring to relative risk (http://en.wikipedia.org/wiki/Relative_risk http://en.wikipedia.org/wiki/Relative_risk). But as I said, there is no reason that relative risk should be considered in this case.
  - DenisM 13y ago
    I see your point. I wonder though if there should be a cutoff somewhere, below which you stop caring? I used background cancer rates as an anchor to judge if the cutoff has been reached, without getting specific about benefits of treatment in each particular case. Would you suggest another cutoff level that is broadly applicable?
    - yetanotherphd 13y ago
      I think the only comparison that makes sense is the benefit from the scan. So if you are certain that the benefit of the scan is, no matter what the particular case, going to be worth much more than a 1/1000 chance of getting cancer, then that is a reason to ignore the risk.
- lvs 13y ago
  Taking your numbers at face value, it seems the problem you're having is the epidemiological interpretation of risk as it pertains to patient populations. You can decide for yourself if a 1/2600 risk is acceptable to you, but doctors are in a position to decide for a far larger number of people. If 10m people are exposed per year to the given risk you outline, the expected number of additional cancers is ~4k people over 20y. In 10 years of scanning, that's 40k additional cancers over the next 30 years. For elderly people over 70, this may be less of an issue, but for everyone else, this is definitely a problem!
- Gatsky 13y ago
  Epidemiological studies likely overstate the risk. If you read the Australian study for example, they certainly could not determine with certainty how many CT scans an individual had, because they did not include CT scans performed in hospitals. I would say that MOST CT scans performed in children would happen in hospitals. Therefore, a person having one CT may simply be a marker of them having many more CTs which are not captured by the study. There were also other unusual correlations in the data. For example, CT scans of the brain seemed to increase the risk of cancer elsewhere in the body, and scans of the abdomen increased the risk of brain cancer. This seems implausible, and implies to me that at least some of the correlation between CTs and cancer is likely to be explained by some third factor whereby people with an increased risk for cancer have more CT scans. The most telling correlations are probably for rare tumours, like soft tissue cancers eg sarcoma, which show an increased risk post CT. These cancers are rare and have few known risk factors, so this correlation is more believable. But these events were much rarer than all cancers in the cohort.
  - einhverfr 13y ago
    But doesn't this effectively reduce to "we don't know?" FWIW I have had one CT scan in my life (in childhood I had a seizure which was probably caused by medicines I was taking) and they did one to rule out brain tumors. Probably a reasonable choice given that all the other tests for other stuff kept coming back negative. But I wouldn't suggest doing one without either a clear immediate need or else a significant concern and no materialized alternative causes for a symptom.
- gcb0 13y ago
  you are probably right. I know several people who fought or died of cancer. None ever had a CT scan. Or that many X-rays to begin with.
- 300bps 13y ago
  The article is terrible and you've done a good job of explaining why. But there are two ways to look at this: 1. From an individual's perspective 2. From society's perspective Let's make up some numbers for illustration. If getting a CT scan gives someone 0.01% chance of getting cancer, the risk to any individual is negligible. But to society, that means 100 extra cases of cancer.
  - userbinator 13y ago
    100 extra cases of cancer out of how many already...? Yes, it's negligible either way.
    - 300bps 13y ago
      Yes, it's negligible either way But doctors have that pesky "do no harm" credo that makes them consider whether the benefit of CT scans is worth the harm of 100 people getting cancer that wouldn't have otherwise gotten it. It is proper for society to examine this without dismissing 100 people getting cancer as "negligible".
- leoc 13y ago
  Interestingly Stewart Brand was out this year arguing http://edge.org/response-detail/25392 http://edge.org/response-detail/25392 against of the the Linear No-Threshold model of radiation risk: "The "Linear" part of the LNT is true and well documented. Based on long-term studies of survivors of the atomic bombs in Japan and of nuclear industry workers, the incidence of eventual cancer increases with increasing exposure to radiation at levels above 100 millisieverts/year. The effect is linear. Below 100 millisieverts/year, however, no increased cancer incidence has been detected, either because it doesn't exist or because the numbers are so low that any signal gets lost in the epidemiological noise." IDK if his case if convincing or not. In any case, even if say 10, 50 or 100 millisieverts a year is something the human body can shrug off with no increase in risk, I imagine that might not apply to 10-30 millisieverts delivered in a very short interval of time.
nostromo 13y ago
This goes beyond the medical field. ProPublica did a story about how X-rays are becoming more common in law-enforcement and border security as well. http://www.propublica.org/article/drive-by-scanning-officials-expand-use-and-dose-of-radiation-for-security-s http://www.propublica.org/article/drive-by-scanning-official...
- ImprovedSilence 13y ago
  THAT is what scares the willys outta me. Because we've all seen how far those types of agencies will take these types of "security measures".
- tlrobinson 13y ago
  Is there a relatively inexpensive portable Geiger counter or something that can measure this type of radiation?
  - jorgem 13y ago
    http://www.amazon.com/RADStickerTM-radiation-exposure-determining-dosimeter/dp/B004VJ06CI/ref=sr_1_1?ie=UTF8&qid=1391321366&sr=8-1&keywords=dosimeter http://www.amazon.com/RADStickerTM-radiation-exposure-determ...
    - kaybe 13y ago
      Or you could just get an app (and some black tape), depending on the energy range you want to look at: http://www.xinexus.ch/nuclear-radiation-dosimeter/index.html http://www.xinexus.ch/nuclear-radiation-dosimeter/index.html edit: I think I got the wrong thing there.. better go for this: http://www.hotray-info.de/html/radioactivity.html http://www.hotray-info.de/html/radioactivity.html
refurb 13y ago
I have no doubt that patients are getting exposed to more radiation via imaging than they need to. However, every decision in medicine is (or should be) a risk-vs-benefit analysis. Cancer is not the only thing you can die from. If you suffer a head injury and end up in the ER and get a CT scan, you may increase your long-term risk of cancer, but you are also drastically reducing the risk of dying from a brain hemorrhage that couldn't be identified by any other method.
- skue 13y ago
  Of course, no one would dispute ordering a CT for a trauma patient if the presentation warrants. But the article was talking about the increase in CT usage over the past 20 years. That's largely been driven (in the US) by misaligned incentives that reimburse procedures at much higher rates that clinical decision making. Put simply, the person who owns the CT machine makes much more than the doctor who interprets the results. And so we have had a blossoming of imaging centers, and CT machines have moved into outpatient cardiology and even family care practices. One of the major goals of Obamacare is addressing these misaligned incentives and shifting to a model where providers are paid to keep people healthy (outcome driven) rather than on volume (fee for service). Another issue has been the difficulty of sharing/accessing existing imaging data, so tests are just repeated to save time (rather that save cost or adequately balance safety). Our long, painful journey to electronic record standardization should also help with that.
  - carbocation 13y ago
    CT is also simply more available, so it's an option. In the past, not so much.
- bradleyjg 13y ago
  The doctors are doing a risk/benefit analysis: the risk is to the patient and the benefit is to their wallets. It's a no brainer. Everyone likes to shit on lawyers, but US doctors routinely take on, and fail to disclose, conflicts of interest that would get a lawyer disbarred in a heartbeat.
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petersellers 13y ago
The article's first sentence annoys me right off the bat: "Despite great strides in prevention and treatment, cancer rates remain stubbornly high and may soon surpass heart disease as the leading cause of death in the United States." This seems to be implying that cancer death rates are growing and will soon "surpass" those of heart disease. While the article is technically correct, this is due to the fact that deaths per year from heart disease have been going down in the US since 1975 (see here: http://www.heart.org/idc/groups/heart-public/@wcm/@sop/@smd/documents/downloadable/ucm_449847.pdf http://www.heart.org/idc/groups/heart-public/@wcm/@sop/@smd/...) It's irritating because the article's premise is flawed. It also gives no statistical data to back the claim that cancer rates are increasing.
- darkxanthos 13y ago
  It also seems to imply that medical tests which expose us to radiation are the cause of supposedly increasing cancer rates... which _seems_ a bit alarmist?
  - latk 13y ago
    That would actually be a sound argument: If we assume a linear damage model for radiation exposure (which is a generally accepted model for these circumstances), then there is no safe dose. Instead, any exposure increases your lifetime risk of cancer. It is therefore not useful to talk about how medical imaging causes an individual case of cancer. But for a larger population we can figure out what the cancer risk without medical radiation exposure would be, and what the observed probability is. We can then ascribe the difference to these medical tests. Obviously there are a number of ways to fuck up this analysis. Geological differences in the natural radiation dose shouldn't be underestimated. However, almost half of the lifetime radiation dose of a human does come from medical applications, and it would certainly be good to reduce that.
    - darkxanthos 13y ago
      Really... fixating on the risk of cancer at all is a mistake. As other commenters have said, it's about balancing the risk with the value. Instead, we should find a) How much radiation one might on average incur due to medical reasons b) How many years of life that causes us to lose on average (or per capita) c) How many years of life the average person gains due to the use of this technology. As long as c - b > 0 (in a real way) we don't really have a problem here. We have an optimization to make. I don't see any evidence here that c - b <= 0. I also don't see any evidence that c - b > 0. Any other point seems moot.
Zigurd 13y ago
Of course I'd rather get a CT scan sooner than an MRI later if I'm a serious trauma patient. But CT scans are way over-used for procedures that are not time-critical.
sjtrny 13y ago
"We are giving ourselves cancer by living long enough to develop it" is what the title should have said. This article is the worst form of opinion.
- sgustard 13y ago
  Agree, and it's not opinion, it's scare-mongering linkbait. Ridiculous to see that along with no actionable data from NYT. I'm giving myself a stroke just thinking about it.
dnautics 13y ago
Big elephant in the room: Pre-test ban atmospheric nuclear tests. Of course, there's nothing anyone can do about it. The somatic damage period is probably more or less over, but we are transitioning through the genetic damage period.
- vectorjohn 13y ago
  If this was a big elephant in the room, then I would expect there to be some modicum of evidence that this causes any increase in cancer risk. Maybe a shred of evidence that cancer rates have gone up? Anything. We'll wait.
  - dnautics 13y ago
    It's untestable, because there's no null control. That doesn't mean it's not real.
- throwaway_yy2Di 13y ago
  Squeaky mouse in the room: the actual numbers. https://en.wikipedia.org/wiki/Background_radiation https://en.wikipedia.org/wiki/Background_radiation Natural background: 2.40 mSv/year (world average) Atmospheric testing: "peak of 0.11 mSv in 1963"
  - dnautics 13y ago
    Isotopes of specific atoms have a different biochemical targetting and effect than EM radiation. Iodine is concentrated in the thyroid, strontium makes its way to the bone (close to hematopoetic stem cells), etc.
mathgeek 13y ago
I liked the part about them causing "excess deaths." It's good to know your chance of dying is lower if you avoid CT scans...
- DanBC 13y ago
  People are harmed when they get unnecessary CT scans. Not from the CT scanning but from the unneeded treatment they get after that.
adrr 13y ago
Cancers rates are have been on the decline or remaining steady not rising. Look at the stats for the most common types of cancer. http://seer.cancer.gov/statfacts/html/prost.html http://seer.cancer.gov/statfacts/html/prost.html http://seer.cancer.gov/statfacts/html/colorect.html http://seer.cancer.gov/statfacts/html/colorect.html http://seer.cancer.gov/statfacts/html/breast.html http://seer.cancer.gov/statfacts/html/breast.html http://seer.cancer.gov/statfacts/html/lungb.html http://seer.cancer.gov/statfacts/html/lungb.html
- scotty79 13y ago
  I wonder how discouraging people from air travel influences cancer rates...
gadr90 13y ago
As a person who had two minor head injuries and took a CT after each one (to find nothing, thankfully) in the last 6 months... I find this rather disturbing.
- ivanca 13y ago
  I took more than 20 in a couple of months (ordered by myself) after doctors couldn't find anything concrete (later on the current diagnostic is "fybromialgia" and the symptoms remain nearly 2 years later). I was aware of cancer danger but I needed to find some treatment before ending completely mad.
  - bloopletech 13y ago
    You may be interested in http://www.intidyn.com/Newsroom/article-0009.html http://www.intidyn.com/Newsroom/article-0009.html - the probable cause of fibro has been identified - which will be a huge boon to the sufferers - including my girlfriend.
    - ivanca 13y ago
      Than you. I'm very up to the news on r/fibro (reddit) and I already read that article but I'm glad you brought it up here. Since my diagnostic I'm also trying to make my way to develop health tech that could help mitigate (completely or partially) the pain and the other symptoms, so now I'm living in the bay area instead of my own country.
pessimism 13y ago
Any people here who go to the dentist? Specifically, the American Dental Association's guidelines for heathy persons suggest that * children receive 1 x-ray every 1-2 years, * teens every 1.5-3 years, * and adults every 2-3 years. ~ http://www.medicalnewstoday.com/releases/243952.php http://www.medicalnewstoday.com/releases/243952.php I was personally very surprised and alarmed by this.
- mhb 13y ago
  Why are you alarmed? How significant is a 5x greater risk of meningioma?
- cloverich 13y ago
  Typical dental x-ray's expose you to drastically less radiation than a CT. Wikipedia: > The dosage of X-ray radiation received by a dental patient is typically small (around 0.150 mSv for a full mouth series, according to the American Dental Association website), equivalent to a few days' worth of background environmental radiation exposure, or similar to the dose received during a cross-country airplane flight (concentrated into one short burst aimed at a small area)
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- DenisM 13y ago
  Before getting alarmed consider doing the math to assign numerical value to level of danger. Wikipedia article on Sievert has the formulas for it, as well as benchmark values to judge the outcome. If you don't want to do the math, consider this handy chart: http://xkcd.com/radiation/ http://xkcd.com/radiation/
  - a8da6b0c91d 13y ago
    The standard defense of the safety of x-ray machines seems to be that you get more radiation from long haul flights. Well, there's a strong argument that flying isn't safe either. Pilots and stewards apparently have elevated cancer rates.
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steveplace 13y ago
>One in 10 Americans undergo a CT scan every year, and many of them get more than one. For what?
- scotty79 13y ago
  For back pain? More than half of the people at some point in life develop some for back pain. It's scary so if you can afford a scan you get it. Of course there's nothing wrong and the pain goes away by itself in following months, usually after switching chair in which you spend most of your waking hours.
  - DanBC 13y ago
    I can't imagine someone in the UK getting scans for lower-back back pain unless there was some clinical need for it. The advice for most people would tend to be "lose weight, get exercise, check your beds and chairs; and carefully take paracetamol for the pain".
97s 13y ago
I am a surviving AML patient, relapsed once and had a stim cell donor. I have had over 50-60 CT scans and I have one or two a month to monitor my lungs for fluids. This article makes me chuckle cause who knows what it's doing to me, but without the CT scans to spot pneumonia and other infections in my lungs I would probably have died already.
- mbreese 13y ago
  Congrats on surviving AML. I have a few oncologist friends. I think that their point of view is that once you go to see them, getting a CT or 50 is the least of your problems. So, if they even think there is something wrong, you're getting a CT. The risk of having a problem now is much worse than the remote risk of something else going wrong in the future. If you survive this bout, who cares about the extra radiation exposure. Being able to worry about that later is a good problem to have.
  - 97s 13y ago
    That's exactly how I feel. CT sure sign me up. Ive had so much chemo therapy and radiation xrays and scans that I am sure my lifespan is shortened a lot. However I am alive 6 more years than I should have been, and I have a son and a wife that I would have never experienced.
cesarbs 13y ago
What about MRIs? Don't they offer the same benefits of CT scans but without all the radiation?
- Someone 13y ago
  No. They have different strengste and weaknesses. Roughly, CT is for bones and rough details of soft tissues, MRI for detailed views on soft tissue in patients without metal implants. More nuanced views at http://www.ct-scan-info.com/mrivsctscan.html http://www.ct-scan-info.com/mrivsctscan.html, http://www.diffen.com/difference/CT_Scan_vs_MRI http://www.diffen.com/difference/CT_Scan_vs_MRI or http://blog.radiology.ucsf.edu/neuroradiology/exploring-the-brain-is-ct-or-mri-better-for-brain-imaging/ http://blog.radiology.ucsf.edu/neuroradiology/exploring-the-... For the discussion at hand, http://en.wikipedia.org/wiki/Magnetic_resonance_imaging#MRI_versus_CT http://en.wikipedia.org/wiki/Magnetic_resonance_imaging#MRI_... has some discussion.
blablabla123 13y ago
I know several people that died of cancer, and as far as I know none of them had a CT scan before it. In contrast, the one who was often scanned during his illness, lived almost 10 years with cancer. The article just says CT scan has higher radiation but other than that no hard facts are presented. Looks like the NYT is writing research articles now...
yeukhon 13y ago
Let's simplify this. Industrial waste is everywhere. Old buildings are built with cancerous materials and we are expose to all kinds of radiations and air pollutions. We eat junk food, we don't exercise much. Kids are playing with toys painted with lethal chemical substances. Second-hand smoking is always present. We eat overfried food and we also sleep late. So the story is clear and doesn't require some heavy scientific investigation. We are risking.
- judk 13y ago
  Sleeping late caused cancer now???
  - yeukhon 13y ago
    http://132.248.16.1/pages/curso_ritmos/capitulo15/Davis.pdf http://132.248.16.1/pages/curso_ritmos/capitulo15/Davis.pdf And weaken your body is one way to allow cancer to spread quicker. http://www.huffingtonpost.com/2013/08/27/stress-cancer-gene-immune-system_n_3804917.html http://www.huffingtonpost.com/2013/08/27/stress-cancer-gene-... If you think cancer is all about radiation, you are wrong..
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cstefanovici 13y ago
Why doesn't anyone mention that our diets are also culprits because they weaken our immune systems. Diets full of fats cholesterol and cooked vegetables do not have the required nutrients that we need day to day. This is pretty eye opening: http://www.imdb.com/title/tt1528734/?ref_=nv_sr_1 http://www.imdb.com/title/tt1528734/?ref_=nv_sr_1
brosco45 13y ago
Yup, and all the advise that helps are being voted down. So we shall enjoy you people getting what you deserve.
DenisM 13y ago
A handy radiation-exposure chart: http://xkcd.com/radiation/ http://xkcd.com/radiation/ It's the first thing I check with before looking for any details (which are conveniently linked at the bottom, by the way).
nipponese 13y ago
Not that we're doing anything to prevent it either... like, for example, exercising.
smegel 13y ago
We also eat a lot more crap today.
- mjhea0 13y ago
  blame monsanto, not our poor decisions
leoc 13y ago
leo'c Law of Medicine: You can get away with Absolutely Anything Whatsoever if you characterise it as a medical treatment.
squirejons 13y ago
since the media is now exposing this secret there must have already been a decline in CT scans, otherwise the media would never say a word about it. The media never exposes a mainstream money making scam until the money has gone out of it.
rdl 13y ago
When I worked with radiologists (at a PACS vendor, mainly selling to the military and the federal prisons), the radiologists and staff were exercising due care about minimizing radiation exposure from CTs. Personally, I don't care about regular x-rays, particularly digital ones, for any reasonable medical use. I get one every year or two as part of a checkup. CT and C-arm fluoroscopy scare me, as an educated person who isn't a doctor but knows more than 99% of people about radiation safety, and I'd want there to be a clear clinical need and decision supported by them. Which is the standard I saw applied. (I never actually saw a c-arm procedure) In extreme trauma you might err on the side of a CT in 1/100 cases. but that's not a big deal.
- a8da6b0c91d 13y ago
  Apparently loads of dentists lost fingers and hands to cancer and bone degeneration before they figured out not to hold the x-ray film themselves. Now they have the patient hold it. It just drives home that the stuff is not harmless.
  - rdl 13y ago
    I want one of these: http://en.wikipedia.org/wiki/Shoe-fitting_fluoroscope http://en.wikipedia.org/wiki/Shoe-fitting_fluoroscope
  - gus_massa 13y ago
    Let’s analyze the worst case scenario: 50 weeks/year * 5 days/week * 8 hours/day * 2 patients/hour = 4000 patients/year So your finger would get 4000 “dental” x-ay of ~5uSv (u=micro), that is 20mSv. For comparison, the radiation worker yearly dose limit is 50mSv, but the 50mSv are distributed to all the body, and you get the 20mSv in your finger. Doesn’t sound good. The problem is the repetition. Taking 4000 dental x-rays in a year is not a good idea. (I’m not sure if someone proved that it’s dangerous, but don’t try this just in case.) This is also the reason why x-rays technicians hide behind a shield while taking the x-ray. * Nobody claims that x-rays are not dangerous. The claim is that the risk is minimal under reasonable use and in some circumstance (for example an accident) the benefits are much bigger than the risks. * And the Linear No-Threshold model is mostly an upper bound, the risk of small radiation dose is perhaps smaller than what is extrapolated from big radiation doses. For example, suppose that 4000000 patients take one dental x-ray and 1000 dentist take 4000 dental x-rays each one. In which group will be bigger the increase of the cancer total number? The Linear No-Threshold model says that the expected number should be equal. But perhaps it’s smaller in the patients group, because the body perhaps can deal better with a low number of problems from radiation.
beloch 13y ago
CT Scan doses vary wildly depending on the type of X-ray (chest, head, limb, etc.), the size of the person, and a lot of other things. The bigger the cross-section of the thing you put in a scanner, the greater the exposure. CT machines themselves also vary considerably. Newer machines are often more sensitive and employ better imaging software, so they can do their job while delivering a much smaller dose. Anyone who quotes a solid number is probably using one that's absolute worst-case, which probably means a chest scan on a fat dude with a CT machine that's been around as long as disco music. Personally, I like to think of medical imaging in terms of how long I'd have to work as a flight-attendant to get the same dose. When you fly at high altitudes (as most passenger jets do) there is less atmosphere to block cosmic radiation, which is the source of background radiation that we're exposed to every day. You get a higher dose of radiation at high altitudes amounting to a few tens of microsievert's for a decently long flight. Medical X-Rays that consist of a single photo are approximately in the same ball-park as an intercontinental flight or two, or working as a flight-attendant for a day or so. CT scans are in the ballpark of several months working as a flight-attendant. It sounds bad at first, but flight-attendants aren't known to have a massively increased rate of cancer after doing the job for decades. In general, people fear radiation to an extent that is out of proportion with reality. To add more perspective, the background radiation in your living room will add up to a CT scan, most likely, in less than a year (unless you live in very deep mine). You can marginally improve your odds of getting cancer by avoiding medical scans, but only at the cost of massively increasing your odds of dying from something those scans might have helped diagnose. It's not an intelligent trade-off. Yes, unnecessary CT scans are bad, but not as bad as the article claims. The greatest cost of an unnecessary CT scan is probably to those who don't get scanned due to high demand on the machine. This article, by stoking irrational fears of medical imaging, is more likely to harm people than help them. Note: Medical imaging is generally not done very often, is tracked, and is usually performed by trained technicians with quality apparatus. The same is not true of security X-Ray scans, which people can be subjected to much more frequently, are frequently performed by the near-unemployable, and use machines that are not designed with the primary goal of helping those it scans. The U.S. is also starting to use truck-based scanners to scan parked vehicles and people on public streets. You may be scanned by these not only without consent, but without knowledge. I do find this to be objectionable.
tokenadult 13y ago
The xkcd chart on dosages of ionizing radiation http://xkcd.com/radiation/ http://xkcd.com/radiation/ is a good introduction to the orders of magnitude differences in exposures from different kinds of sources.
- hrjet 13y ago
  It would have been more helpful if that chart didn't mix the units of time.
RK 13y ago
Just FYI, there are a couple of initiatives in the medical imaging world to reduce over exposure: * http://www.imagewisely.org/ http://www.imagewisely.org/ * http://www.imagegently.org/ http://www.imagegently.org/
ryanmarsh 13y ago
Ok fine, except that cancer is well... complicated. http://www.phdcomics.com/comics/archive.php?comicid=1162 http://www.phdcomics.com/comics/archive.php?comicid=1162
NN88 13y ago
I've had a theory that TSA workers will start reporting higher than average cancer rates soon.
xpda 13y ago
We are giving ourselves cancer when we spend time outdoors without sunscreen or other protection.
ypmagic 13y ago
Stay around some carpet. The carpet absorbs the radiation from electronics that you're all concerned about... I think so. Does carpet only absorb sound?
jleahy 13y ago
People who receive CT scans have a higher rate of cancer. This seems like a logical fallacy. People who receive CT scans are more likely to get cancer. So CT scans must cause cancer. The alternate hypothesis are that people who are more likely to develop cancer are more likely to have a CT scan. Given the tiny number involved here (in absolute number of people who develop cancer after having a CT scan), is it not possible that these people had a CT scan because of early symptoms of cancer?
fredgrott 13y ago
Actually at least in the USA there are geographic portions of the USA where radon gases via what the house foundation was built on are more of a threat than tracked medical imaging as obviously if the house is not tested than we have no way of determining whether radon gas is a threat. EPA map of radon gas zones, Zone 3 is the high risk level: http://www.epa.gov/radon/pdfs/zonemapcolor.pdf http://www.epa.gov/radon/pdfs/zonemapcolor.pdf and no sarcastic comments about it also being the bible belt please..:)
smalldaddy 13y ago
The article misses a very important point. People are living longer because of better heart care (lower death rates at a given age from heart disease). All else being equal, this means people are living longer, which in turn means they are at increased risk of getting cancer. The CT scan impact is small in comparison with this fact.
md9999 13y ago
This article does not represent current state of knowledge in this field, and makes many misleading statements. I have presented a line-by-line criticism of the article in my blog which is available at: http://are-we-really-giving-ourselves-cancer.blogspot.com/ http://are-we-really-giving-ourselves-cancer.blogspot.com/ CT scans are safe, and the present concerns regarding radiation dose from CT scans are not justified by any evidence.
mdoss99 13y ago
This article does not represent current state of knowledge in this field, and makes many misleading statements. I have presented a line-by-line criticism of the article in my blog which is available at: http://are-we-really-giving-ourselves-cancer.blogspot.com/ http://are-we-really-giving-ourselves-cancer.blogspot.com/ CT scans are safe, and the present concerns regarding radiation dose from CT scans are not justified by any evidence.

260 points by uladzislau 13y ago

>A single CT scan exposes a patient to the amount of radiation that epidemiologic evidence shows can be cancer-causing That does not look right to me. A single CT scan is 2-7 millisieverts, and exposures under 13 can not be linked to health effects - look for UNSCEAR in http://en.m.wikipedia.org/wiki/Sievert http://en.m.wikipedia.org/wiki/Sievert If you do the math by ICRP formulae, you end up with increase chance of cancer of 1 in 2600 over the next 20 years from a single 7ms CT scan today. This compares favorably with "natural" risk that is 1 in 10 without any extra exposure above background radiation. Now if you do a scan every year for the next 20 years your chances go up to 1 in 130. So there is something to worry about, but article overstates the cause.

Zigurd 13y ago
> Now if you do a scan every year for the next 20 years your chances go up to 1 in 130 Unless the article is wrong about the number of CT scans many people are getting, that's going to result is a huge number of avoidable cancer cases.
- 001sky 13y ago
  The distribution of these cases is likely to skew towards the Elderly and over 50 demographic. I'd be curious to see the impact of this on the analysis.
- pedalpete 13y ago
  I'm not very good at math, but I'm reading that as a 0.7% increase in your chance of getting cancer. From 'Physics for Future Presidents', they say it is commonly accepted that we have a 20% chance of DYING from cancer before calculating for outside influences. http://books.google.com.au/books?id=6DBnS2g-KrQC&pg=PA98&lpg=PA98&dq=physics+for+future+presidents+cancer&source=bl&ots=_0qSSAxozw&sig=mGZEYJPaciupf-a7ZUCS_HIEhac&hl=en&sa=X&ei=XZvtUqnqNsmZiQfq8IDQAQ&ved=0CCYQ6AEwAA#v=onepage&q=physics%20for%20future%20presidents%20cancer&f=false http://books.google.com.au/books?id=6DBnS2g-KrQC&pg=PA98&lpg... Let's say the average person does not get a CT scan every year for 20 years, but rather gets 5 scans over their lifetime. Those scans may detect an early stage of cancer, therefore saving the persons life. They're risk of dying from cancer is approximately 20.2%. I suggest with the CT scan, their still coming out on top.
  - novaleaf 13y ago
    that's an extra 0.7% for you. For a population of 300m (about the pop of the usa) that'd be an extra 2.1m people getting cancer.
    - monkeyspaw 13y ago
      Any idea what the error bars are on that .7% figure?
deleted 13y ago
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pbreit 13y ago
The Wikipedia article lists a full body CT scan at 10-30 mSv.
- DenisM 13y ago
  I was going off the list http://en.m.wikipedia.org/wiki/X-ray_computed_tomography http://en.m.wikipedia.org/wiki/X-ray_computed_tomography and in haste I stopped after head and chest. You are right, I should have gone further down to the full-body as well. Thanks for that. Incidentally, this is exactly why I included the numbers - so you can check them, and why I don't like the headline article - no numbers and no references, so there is nothing to check, only vaguely scary claims.
  - rdl 13y ago
    Newer machines are at least reducing the radiation. This is due to better compute power and to better sensors (essentially a mineral which converts x-rays into flashes of light which then get captured by a photodiode). It's been huge in dental x-rays, going from film to CR/DR (although dental isn't huge, it's routine, and involves a large patient population including kids.) We probably will be <5 mSv for whole-body pretty soon. Ultimately there's no reason it can't be well under 1 mSv. Fluoroscopy on the other hand is easily 50 mSv/min and multi-hour procedures (!!!). People get acute effects from that.
redschell 13y ago
The American Association of Physicists in Medicine seems to have your back: http://www.usnews.com/science/articles/2012/01/17/phsycists-fear-of-diagnostic-radiation-is-overblown http://www.usnews.com/science/articles/2012/01/17/phsycists-... A full-body CT scan results in 12 mSv; a mammogram 0.13 mSv—a hundred times less. The risks from these procedures, according to AAPM, are too low to have been determined reliably, and may be "nonexistent." Looks like this debate has been going on for a while now.
- johnjm 13y ago
  Here[1] is a very recent study from Austrialia which concludes CT scans during childhood and adolescent increase the risk of cancer and should be avoided where possible. [1] http://www.bmj.com/content/346/bmj.f2360 http://www.bmj.com/content/346/bmj.f2360
yetanotherphd 13y ago
>If you do the math by ICRP formulae, you end up with increase chance of cancer of 1 in 2600 over the next 20 years from a single 7ms CT scan today. This compares favorably with "natural" risk that is 1 in 10 without any extra exposure above background radiation. But that is a meaningless comparison. The doctor should be comparing this additional risk, to the benefit of the scan. The "natural" risk of developing cancer is totally irrelevant to the cost-benefit analysis.
- carbocation 13y ago
  Because we operate in likelihood ratios, the unexposed risk is important so the risk can be computed (at least, in theory; in practice, people go more by indication than by formal risk prob/benefit prob).
  - yetanotherphd 13y ago
    That still makes no sense. If I want to know whether to do a CT scan, the only relevant fact is the increase in probability (in an absolute sense) of cancer that it causes. It seems like either you, or the entire field of medicine, is obfuscating this basic fact using some field-specific concepts. EDIT: It seems like you are referring to relative risk (http://en.wikipedia.org/wiki/Relative_risk http://en.wikipedia.org/wiki/Relative_risk). But as I said, there is no reason that relative risk should be considered in this case.
- DenisM 13y ago
  I see your point. I wonder though if there should be a cutoff somewhere, below which you stop caring? I used background cancer rates as an anchor to judge if the cutoff has been reached, without getting specific about benefits of treatment in each particular case. Would you suggest another cutoff level that is broadly applicable?
  - yetanotherphd 13y ago
    I think the only comparison that makes sense is the benefit from the scan. So if you are certain that the benefit of the scan is, no matter what the particular case, going to be worth much more than a 1/1000 chance of getting cancer, then that is a reason to ignore the risk.
lvs 13y ago
Taking your numbers at face value, it seems the problem you're having is the epidemiological interpretation of risk as it pertains to patient populations. You can decide for yourself if a 1/2600 risk is acceptable to you, but doctors are in a position to decide for a far larger number of people. If 10m people are exposed per year to the given risk you outline, the expected number of additional cancers is ~4k people over 20y. In 10 years of scanning, that's 40k additional cancers over the next 30 years. For elderly people over 70, this may be less of an issue, but for everyone else, this is definitely a problem!
Gatsky 13y ago
Epidemiological studies likely overstate the risk. If you read the Australian study for example, they certainly could not determine with certainty how many CT scans an individual had, because they did not include CT scans performed in hospitals. I would say that MOST CT scans performed in children would happen in hospitals. Therefore, a person having one CT may simply be a marker of them having many more CTs which are not captured by the study. There were also other unusual correlations in the data. For example, CT scans of the brain seemed to increase the risk of cancer elsewhere in the body, and scans of the abdomen increased the risk of brain cancer. This seems implausible, and implies to me that at least some of the correlation between CTs and cancer is likely to be explained by some third factor whereby people with an increased risk for cancer have more CT scans. The most telling correlations are probably for rare tumours, like soft tissue cancers eg sarcoma, which show an increased risk post CT. These cancers are rare and have few known risk factors, so this correlation is more believable. But these events were much rarer than all cancers in the cohort.
- einhverfr 13y ago
  But doesn't this effectively reduce to "we don't know?" FWIW I have had one CT scan in my life (in childhood I had a seizure which was probably caused by medicines I was taking) and they did one to rule out brain tumors. Probably a reasonable choice given that all the other tests for other stuff kept coming back negative. But I wouldn't suggest doing one without either a clear immediate need or else a significant concern and no materialized alternative causes for a symptom.
gcb0 13y ago
you are probably right. I know several people who fought or died of cancer. None ever had a CT scan. Or that many X-rays to begin with.
300bps 13y ago
The article is terrible and you've done a good job of explaining why. But there are two ways to look at this: 1. From an individual's perspective 2. From society's perspective Let's make up some numbers for illustration. If getting a CT scan gives someone 0.01% chance of getting cancer, the risk to any individual is negligible. But to society, that means 100 extra cases of cancer.
- userbinator 13y ago
  100 extra cases of cancer out of how many already...? Yes, it's negligible either way.
  - 300bps 13y ago
    Yes, it's negligible either way But doctors have that pesky "do no harm" credo that makes them consider whether the benefit of CT scans is worth the harm of 100 people getting cancer that wouldn't have otherwise gotten it. It is proper for society to examine this without dismissing 100 people getting cancer as "negligible".
leoc 13y ago
Interestingly Stewart Brand was out this year arguing http://edge.org/response-detail/25392 http://edge.org/response-detail/25392 against of the the Linear No-Threshold model of radiation risk: "The "Linear" part of the LNT is true and well documented. Based on long-term studies of survivors of the atomic bombs in Japan and of nuclear industry workers, the incidence of eventual cancer increases with increasing exposure to radiation at levels above 100 millisieverts/year. The effect is linear. Below 100 millisieverts/year, however, no increased cancer incidence has been detected, either because it doesn't exist or because the numbers are so low that any signal gets lost in the epidemiological noise." IDK if his case if convincing or not. In any case, even if say 10, 50 or 100 millisieverts a year is something the human body can shrug off with no increase in risk, I imagine that might not apply to 10-30 millisieverts delivered in a very short interval of time.

nostromo 13y ago

This goes beyond the medical field. ProPublica did a story about how X-rays are becoming more common in law-enforcement and border security as well. http://www.propublica.org/article/drive-by-scanning-officials-expand-use-and-dose-of-radiation-for-security-s http://www.propublica.org/article/drive-by-scanning-official...

ImprovedSilence 13y ago
THAT is what scares the willys outta me. Because we've all seen how far those types of agencies will take these types of "security measures".
tlrobinson 13y ago
Is there a relatively inexpensive portable Geiger counter or something that can measure this type of radiation?
- jorgem 13y ago
  http://www.amazon.com/RADStickerTM-radiation-exposure-determining-dosimeter/dp/B004VJ06CI/ref=sr_1_1?ie=UTF8&qid=1391321366&sr=8-1&keywords=dosimeter http://www.amazon.com/RADStickerTM-radiation-exposure-determ...
  - kaybe 13y ago
    Or you could just get an app (and some black tape), depending on the energy range you want to look at: http://www.xinexus.ch/nuclear-radiation-dosimeter/index.html http://www.xinexus.ch/nuclear-radiation-dosimeter/index.html edit: I think I got the wrong thing there.. better go for this: http://www.hotray-info.de/html/radioactivity.html http://www.hotray-info.de/html/radioactivity.html

refurb 13y ago

I have no doubt that patients are getting exposed to more radiation via imaging than they need to. However, every decision in medicine is (or should be) a risk-vs-benefit analysis. Cancer is not the only thing you can die from. If you suffer a head injury and end up in the ER and get a CT scan, you may increase your long-term risk of cancer, but you are also drastically reducing the risk of dying from a brain hemorrhage that couldn't be identified by any other method.

skue 13y ago
Of course, no one would dispute ordering a CT for a trauma patient if the presentation warrants. But the article was talking about the increase in CT usage over the past 20 years. That's largely been driven (in the US) by misaligned incentives that reimburse procedures at much higher rates that clinical decision making. Put simply, the person who owns the CT machine makes much more than the doctor who interprets the results. And so we have had a blossoming of imaging centers, and CT machines have moved into outpatient cardiology and even family care practices. One of the major goals of Obamacare is addressing these misaligned incentives and shifting to a model where providers are paid to keep people healthy (outcome driven) rather than on volume (fee for service). Another issue has been the difficulty of sharing/accessing existing imaging data, so tests are just repeated to save time (rather that save cost or adequately balance safety). Our long, painful journey to electronic record standardization should also help with that.
- carbocation 13y ago
  CT is also simply more available, so it's an option. In the past, not so much.
bradleyjg 13y ago
The doctors are doing a risk/benefit analysis: the risk is to the patient and the benefit is to their wallets. It's a no brainer. Everyone likes to shit on lawyers, but US doctors routinely take on, and fail to disclose, conflicts of interest that would get a lawyer disbarred in a heartbeat.

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petersellers 13y ago

The article's first sentence annoys me right off the bat: "Despite great strides in prevention and treatment, cancer rates remain stubbornly high and may soon surpass heart disease as the leading cause of death in the United States." This seems to be implying that cancer death rates are growing and will soon "surpass" those of heart disease. While the article is technically correct, this is due to the fact that deaths per year from heart disease have been going down in the US since 1975 (see here: http://www.heart.org/idc/groups/heart-public/@wcm/@sop/@smd/documents/downloadable/ucm_449847.pdf http://www.heart.org/idc/groups/heart-public/@wcm/@sop/@smd/...) It's irritating because the article's premise is flawed. It also gives no statistical data to back the claim that cancer rates are increasing.

darkxanthos 13y ago
It also seems to imply that medical tests which expose us to radiation are the cause of supposedly increasing cancer rates... which _seems_ a bit alarmist?
- latk 13y ago
  That would actually be a sound argument: If we assume a linear damage model for radiation exposure (which is a generally accepted model for these circumstances), then there is no safe dose. Instead, any exposure increases your lifetime risk of cancer. It is therefore not useful to talk about how medical imaging causes an individual case of cancer. But for a larger population we can figure out what the cancer risk without medical radiation exposure would be, and what the observed probability is. We can then ascribe the difference to these medical tests. Obviously there are a number of ways to fuck up this analysis. Geological differences in the natural radiation dose shouldn't be underestimated. However, almost half of the lifetime radiation dose of a human does come from medical applications, and it would certainly be good to reduce that.
  - darkxanthos 13y ago
    Really... fixating on the risk of cancer at all is a mistake. As other commenters have said, it's about balancing the risk with the value. Instead, we should find a) How much radiation one might on average incur due to medical reasons b) How many years of life that causes us to lose on average (or per capita) c) How many years of life the average person gains due to the use of this technology. As long as c - b > 0 (in a real way) we don't really have a problem here. We have an optimization to make. I don't see any evidence here that c - b <= 0. I also don't see any evidence that c - b > 0. Any other point seems moot.

Zigurd 13y ago

Of course I'd rather get a CT scan sooner than an MRI later if I'm a serious trauma patient. But CT scans are way over-used for procedures that are not time-critical.

sjtrny 13y ago

"We are giving ourselves cancer by living long enough to develop it" is what the title should have said. This article is the worst form of opinion.

sgustard 13y ago
Agree, and it's not opinion, it's scare-mongering linkbait. Ridiculous to see that along with no actionable data from NYT. I'm giving myself a stroke just thinking about it.

dnautics 13y ago

Big elephant in the room: Pre-test ban atmospheric nuclear tests. Of course, there's nothing anyone can do about it. The somatic damage period is probably more or less over, but we are transitioning through the genetic damage period.

vectorjohn 13y ago
If this was a big elephant in the room, then I would expect there to be some modicum of evidence that this causes any increase in cancer risk. Maybe a shred of evidence that cancer rates have gone up? Anything. We'll wait.
- dnautics 13y ago
  It's untestable, because there's no null control. That doesn't mean it's not real.
throwaway_yy2Di 13y ago
Squeaky mouse in the room: the actual numbers. https://en.wikipedia.org/wiki/Background_radiation https://en.wikipedia.org/wiki/Background_radiation Natural background: 2.40 mSv/year (world average) Atmospheric testing: "peak of 0.11 mSv in 1963"
- dnautics 13y ago
  Isotopes of specific atoms have a different biochemical targetting and effect than EM radiation. Iodine is concentrated in the thyroid, strontium makes its way to the bone (close to hematopoetic stem cells), etc.

mathgeek 13y ago

I liked the part about them causing "excess deaths." It's good to know your chance of dying is lower if you avoid CT scans...

DanBC 13y ago
People are harmed when they get unnecessary CT scans. Not from the CT scanning but from the unneeded treatment they get after that.

adrr 13y ago

Cancers rates are have been on the decline or remaining steady not rising. Look at the stats for the most common types of cancer. http://seer.cancer.gov/statfacts/html/prost.html http://seer.cancer.gov/statfacts/html/prost.html http://seer.cancer.gov/statfacts/html/colorect.html http://seer.cancer.gov/statfacts/html/colorect.html http://seer.cancer.gov/statfacts/html/breast.html http://seer.cancer.gov/statfacts/html/breast.html http://seer.cancer.gov/statfacts/html/lungb.html http://seer.cancer.gov/statfacts/html/lungb.html

scotty79 13y ago
I wonder how discouraging people from air travel influences cancer rates...

gadr90 13y ago

As a person who had two minor head injuries and took a CT after each one (to find nothing, thankfully) in the last 6 months... I find this rather disturbing.

ivanca 13y ago
I took more than 20 in a couple of months (ordered by myself) after doctors couldn't find anything concrete (later on the current diagnostic is "fybromialgia" and the symptoms remain nearly 2 years later). I was aware of cancer danger but I needed to find some treatment before ending completely mad.
- bloopletech 13y ago
  You may be interested in http://www.intidyn.com/Newsroom/article-0009.html http://www.intidyn.com/Newsroom/article-0009.html - the probable cause of fibro has been identified - which will be a huge boon to the sufferers - including my girlfriend.
  - ivanca 13y ago
    Than you. I'm very up to the news on r/fibro (reddit) and I already read that article but I'm glad you brought it up here. Since my diagnostic I'm also trying to make my way to develop health tech that could help mitigate (completely or partially) the pain and the other symptoms, so now I'm living in the bay area instead of my own country.

pessimism 13y ago

Any people here who go to the dentist? Specifically, the American Dental Association's guidelines for heathy persons suggest that * children receive 1 x-ray every 1-2 years, * teens every 1.5-3 years, * and adults every 2-3 years. ~ http://www.medicalnewstoday.com/releases/243952.php http://www.medicalnewstoday.com/releases/243952.php I was personally very surprised and alarmed by this.

mhb 13y ago
Why are you alarmed? How significant is a 5x greater risk of meningioma?
cloverich 13y ago
Typical dental x-ray's expose you to drastically less radiation than a CT. Wikipedia: > The dosage of X-ray radiation received by a dental patient is typically small (around 0.150 mSv for a full mouth series, according to the American Dental Association website), equivalent to a few days' worth of background environmental radiation exposure, or similar to the dose received during a cross-country airplane flight (concentrated into one short burst aimed at a small area)
- deleted 13y ago
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DenisM 13y ago
Before getting alarmed consider doing the math to assign numerical value to level of danger. Wikipedia article on Sievert has the formulas for it, as well as benchmark values to judge the outcome. If you don't want to do the math, consider this handy chart: http://xkcd.com/radiation/ http://xkcd.com/radiation/
- a8da6b0c91d 13y ago
  The standard defense of the safety of x-ray machines seems to be that you get more radiation from long haul flights. Well, there's a strong argument that flying isn't safe either. Pilots and stewards apparently have elevated cancer rates.

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steveplace 13y ago

>One in 10 Americans undergo a CT scan every year, and many of them get more than one. For what?

scotty79 13y ago
For back pain? More than half of the people at some point in life develop some for back pain. It's scary so if you can afford a scan you get it. Of course there's nothing wrong and the pain goes away by itself in following months, usually after switching chair in which you spend most of your waking hours.
- DanBC 13y ago
  I can't imagine someone in the UK getting scans for lower-back back pain unless there was some clinical need for it. The advice for most people would tend to be "lose weight, get exercise, check your beds and chairs; and carefully take paracetamol for the pain".

97s 13y ago

I am a surviving AML patient, relapsed once and had a stim cell donor. I have had over 50-60 CT scans and I have one or two a month to monitor my lungs for fluids. This article makes me chuckle cause who knows what it's doing to me, but without the CT scans to spot pneumonia and other infections in my lungs I would probably have died already.

mbreese 13y ago
Congrats on surviving AML. I have a few oncologist friends. I think that their point of view is that once you go to see them, getting a CT or 50 is the least of your problems. So, if they even think there is something wrong, you're getting a CT. The risk of having a problem now is much worse than the remote risk of something else going wrong in the future. If you survive this bout, who cares about the extra radiation exposure. Being able to worry about that later is a good problem to have.
- 97s 13y ago
  That's exactly how I feel. CT sure sign me up. Ive had so much chemo therapy and radiation xrays and scans that I am sure my lifespan is shortened a lot. However I am alive 6 more years than I should have been, and I have a son and a wife that I would have never experienced.

cesarbs 13y ago

What about MRIs? Don't they offer the same benefits of CT scans but without all the radiation?

Someone 13y ago
No. They have different strengste and weaknesses. Roughly, CT is for bones and rough details of soft tissues, MRI for detailed views on soft tissue in patients without metal implants. More nuanced views at http://www.ct-scan-info.com/mrivsctscan.html http://www.ct-scan-info.com/mrivsctscan.html, http://www.diffen.com/difference/CT_Scan_vs_MRI http://www.diffen.com/difference/CT_Scan_vs_MRI or http://blog.radiology.ucsf.edu/neuroradiology/exploring-the-brain-is-ct-or-mri-better-for-brain-imaging/ http://blog.radiology.ucsf.edu/neuroradiology/exploring-the-... For the discussion at hand, http://en.wikipedia.org/wiki/Magnetic_resonance_imaging#MRI_versus_CT http://en.wikipedia.org/wiki/Magnetic_resonance_imaging#MRI_... has some discussion.

blablabla123 13y ago

I know several people that died of cancer, and as far as I know none of them had a CT scan before it. In contrast, the one who was often scanned during his illness, lived almost 10 years with cancer. The article just says CT scan has higher radiation but other than that no hard facts are presented. Looks like the NYT is writing research articles now...

yeukhon 13y ago

Let's simplify this. Industrial waste is everywhere. Old buildings are built with cancerous materials and we are expose to all kinds of radiations and air pollutions. We eat junk food, we don't exercise much. Kids are playing with toys painted with lethal chemical substances. Second-hand smoking is always present. We eat overfried food and we also sleep late. So the story is clear and doesn't require some heavy scientific investigation. We are risking.

judk 13y ago
Sleeping late caused cancer now???
- yeukhon 13y ago
  http://132.248.16.1/pages/curso_ritmos/capitulo15/Davis.pdf http://132.248.16.1/pages/curso_ritmos/capitulo15/Davis.pdf And weaken your body is one way to allow cancer to spread quicker. http://www.huffingtonpost.com/2013/08/27/stress-cancer-gene-immune-system_n_3804917.html http://www.huffingtonpost.com/2013/08/27/stress-cancer-gene-... If you think cancer is all about radiation, you are wrong..
deleted 13y ago
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cstefanovici 13y ago

Why doesn't anyone mention that our diets are also culprits because they weaken our immune systems. Diets full of fats cholesterol and cooked vegetables do not have the required nutrients that we need day to day. This is pretty eye opening: http://www.imdb.com/title/tt1528734/?ref_=nv_sr_1 http://www.imdb.com/title/tt1528734/?ref_=nv_sr_1

brosco45 13y ago

Yup, and all the advise that helps are being voted down. So we shall enjoy you people getting what you deserve.

DenisM 13y ago

A handy radiation-exposure chart: http://xkcd.com/radiation/ http://xkcd.com/radiation/ It's the first thing I check with before looking for any details (which are conveniently linked at the bottom, by the way).

nipponese 13y ago

Not that we're doing anything to prevent it either... like, for example, exercising.

smegel 13y ago

We also eat a lot more crap today.

mjhea0 13y ago
blame monsanto, not our poor decisions

leoc 13y ago

leo'c Law of Medicine: You can get away with Absolutely Anything Whatsoever if you characterise it as a medical treatment.

squirejons 13y ago

since the media is now exposing this secret there must have already been a decline in CT scans, otherwise the media would never say a word about it. The media never exposes a mainstream money making scam until the money has gone out of it.

rdl 13y ago

When I worked with radiologists (at a PACS vendor, mainly selling to the military and the federal prisons), the radiologists and staff were exercising due care about minimizing radiation exposure from CTs. Personally, I don't care about regular x-rays, particularly digital ones, for any reasonable medical use. I get one every year or two as part of a checkup. CT and C-arm fluoroscopy scare me, as an educated person who isn't a doctor but knows more than 99% of people about radiation safety, and I'd want there to be a clear clinical need and decision supported by them. Which is the standard I saw applied. (I never actually saw a c-arm procedure) In extreme trauma you might err on the side of a CT in 1/100 cases. but that's not a big deal.

a8da6b0c91d 13y ago
Apparently loads of dentists lost fingers and hands to cancer and bone degeneration before they figured out not to hold the x-ray film themselves. Now they have the patient hold it. It just drives home that the stuff is not harmless.
- rdl 13y ago
  I want one of these: http://en.wikipedia.org/wiki/Shoe-fitting_fluoroscope http://en.wikipedia.org/wiki/Shoe-fitting_fluoroscope
- gus_massa 13y ago
  Let’s analyze the worst case scenario: 50 weeks/year * 5 days/week * 8 hours/day * 2 patients/hour = 4000 patients/year So your finger would get 4000 “dental” x-ay of ~5uSv (u=micro), that is 20mSv. For comparison, the radiation worker yearly dose limit is 50mSv, but the 50mSv are distributed to all the body, and you get the 20mSv in your finger. Doesn’t sound good. The problem is the repetition. Taking 4000 dental x-rays in a year is not a good idea. (I’m not sure if someone proved that it’s dangerous, but don’t try this just in case.) This is also the reason why x-rays technicians hide behind a shield while taking the x-ray. * Nobody claims that x-rays are not dangerous. The claim is that the risk is minimal under reasonable use and in some circumstance (for example an accident) the benefits are much bigger than the risks. * And the Linear No-Threshold model is mostly an upper bound, the risk of small radiation dose is perhaps smaller than what is extrapolated from big radiation doses. For example, suppose that 4000000 patients take one dental x-ray and 1000 dentist take 4000 dental x-rays each one. In which group will be bigger the increase of the cancer total number? The Linear No-Threshold model says that the expected number should be equal. But perhaps it’s smaller in the patients group, because the body perhaps can deal better with a low number of problems from radiation.

beloch 13y ago

CT Scan doses vary wildly depending on the type of X-ray (chest, head, limb, etc.), the size of the person, and a lot of other things. The bigger the cross-section of the thing you put in a scanner, the greater the exposure. CT machines themselves also vary considerably. Newer machines are often more sensitive and employ better imaging software, so they can do their job while delivering a much smaller dose. Anyone who quotes a solid number is probably using one that's absolute worst-case, which probably means a chest scan on a fat dude with a CT machine that's been around as long as disco music. Personally, I like to think of medical imaging in terms of how long I'd have to work as a flight-attendant to get the same dose. When you fly at high altitudes (as most passenger jets do) there is less atmosphere to block cosmic radiation, which is the source of background radiation that we're exposed to every day. You get a higher dose of radiation at high altitudes amounting to a few tens of microsievert's for a decently long flight. Medical X-Rays that consist of a single photo are approximately in the same ball-park as an intercontinental flight or two, or working as a flight-attendant for a day or so. CT scans are in the ballpark of several months working as a flight-attendant. It sounds bad at first, but flight-attendants aren't known to have a massively increased rate of cancer after doing the job for decades. In general, people fear radiation to an extent that is out of proportion with reality. To add more perspective, the background radiation in your living room will add up to a CT scan, most likely, in less than a year (unless you live in very deep mine). You can marginally improve your odds of getting cancer by avoiding medical scans, but only at the cost of massively increasing your odds of dying from something those scans might have helped diagnose. It's not an intelligent trade-off. Yes, unnecessary CT scans are bad, but not as bad as the article claims. The greatest cost of an unnecessary CT scan is probably to those who don't get scanned due to high demand on the machine. This article, by stoking irrational fears of medical imaging, is more likely to harm people than help them. Note: Medical imaging is generally not done very often, is tracked, and is usually performed by trained technicians with quality apparatus. The same is not true of security X-Ray scans, which people can be subjected to much more frequently, are frequently performed by the near-unemployable, and use machines that are not designed with the primary goal of helping those it scans. The U.S. is also starting to use truck-based scanners to scan parked vehicles and people on public streets. You may be scanned by these not only without consent, but without knowledge. I do find this to be objectionable.

tokenadult 13y ago

The xkcd chart on dosages of ionizing radiation http://xkcd.com/radiation/ http://xkcd.com/radiation/ is a good introduction to the orders of magnitude differences in exposures from different kinds of sources.

hrjet 13y ago
It would have been more helpful if that chart didn't mix the units of time.

RK 13y ago

Just FYI, there are a couple of initiatives in the medical imaging world to reduce over exposure: * http://www.imagewisely.org/ http://www.imagewisely.org/ * http://www.imagegently.org/ http://www.imagegently.org/

ryanmarsh 13y ago

Ok fine, except that cancer is well... complicated. http://www.phdcomics.com/comics/archive.php?comicid=1162 http://www.phdcomics.com/comics/archive.php?comicid=1162

NN88 13y ago

I've had a theory that TSA workers will start reporting higher than average cancer rates soon.

xpda 13y ago

We are giving ourselves cancer when we spend time outdoors without sunscreen or other protection.

ypmagic 13y ago

Stay around some carpet. The carpet absorbs the radiation from electronics that you're all concerned about... I think so. Does carpet only absorb sound?

jleahy 13y ago

People who receive CT scans have a higher rate of cancer. This seems like a logical fallacy. People who receive CT scans are more likely to get cancer. So CT scans must cause cancer. The alternate hypothesis are that people who are more likely to develop cancer are more likely to have a CT scan. Given the tiny number involved here (in absolute number of people who develop cancer after having a CT scan), is it not possible that these people had a CT scan because of early symptoms of cancer?

fredgrott 13y ago

Actually at least in the USA there are geographic portions of the USA where radon gases via what the house foundation was built on are more of a threat than tracked medical imaging as obviously if the house is not tested than we have no way of determining whether radon gas is a threat. EPA map of radon gas zones, Zone 3 is the high risk level: http://www.epa.gov/radon/pdfs/zonemapcolor.pdf http://www.epa.gov/radon/pdfs/zonemapcolor.pdf and no sarcastic comments about it also being the bible belt please..:)

smalldaddy 13y ago

The article misses a very important point. People are living longer because of better heart care (lower death rates at a given age from heart disease). All else being equal, this means people are living longer, which in turn means they are at increased risk of getting cancer. The CT scan impact is small in comparison with this fact.

md9999 13y ago

This article does not represent current state of knowledge in this field, and makes many misleading statements. I have presented a line-by-line criticism of the article in my blog which is available at: http://are-we-really-giving-ourselves-cancer.blogspot.com/ http://are-we-really-giving-ourselves-cancer.blogspot.com/ CT scans are safe, and the present concerns regarding radiation dose from CT scans are not justified by any evidence.

mdoss99 13y ago