Why are MRI machines so expensive to operate?

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MRI machines are expensive to operate primarily due to high capital costs, which can range from $1 million to $3 million, along with significant operating expenses such as electricity, trained personnel, and liability insurance. The detailed imaging provided by MRI technology, which does not use ionizing radiation like CT scans, contributes to its perceived value despite the costs. Patient experiences highlight concerns about the financial motivations of healthcare providers, particularly when additional scans are recommended without clear justification. The complexity of MRI technology and the need for specialized training to operate and interpret results further drive up costs. Overall, the combination of these factors results in high prices for MRI services in healthcare settings.
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Are MRI machines a huge undertaking? They are one of few medical imagers that don't ionize the crap out of us.
Why is MRI machine use so expensive? Is creating a magnet field of that strength difficult and pricey? I think you get better detail than CT scans that do use radiation. Why the high price? Anyone know?
 
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LightningInAJar said:
Not so much the profit margin.
That is a cost to the buyer, either patient or insurance company.

The technology can be pricey as phinds indicated in his second post.
phinds said:
google is your friend

https://heartlandimagingcenters.com/2021/03/19/why-are-mris-so-expensive-at-hospitals/

There is the capital cost of the machine, which can vary widely ("typical prices range from $1 million to as high as $3 million for a single, state-of-the-art, high-powered MRI machine that can deliver the most detailed results"), then there is the operating cost (electrical usage and trained personnel), administrative cost, liability insurance (can be substantial for diagnosticians), salaries of doctors/nurses, and profit.

A neurologist recommended (prescribed) an MRI for my daughter. The cost was about $800, of which the insurance paid $640 (0.80 of customary). We found out after the fact that the doctor was a partner in the radiology group, so he was making some bucks on MRIs. In addition, we were told that the clinic did not do the full MRI, so we needed another MRI done. When the neurologist could not (or would not) give a prognosis, but recommended more tests, we went elsewhere.

My daughter's health and welfare was on the line, and I didn't care for the neurologist's attitude. Of course, I going to pay for whatever my daughter needs to be healthy, but I felt the neurologist was more concerned about making money than patient care.
 
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berkeman said:
That is a very inaccurate thing to say, IMO. Would you like to post some links to reputable medical websites that say that modern X-Ray imaging technologies (including CT imaging) "ionize the crap out of us"?

Flippant perhaps and overstated . Not entirely inaccurate I think but I am not an expert and you likely know more than I.
Because of a weird , unpleasant, and acute (autoimmune) encephalitis five years ago my neurologist suggested I have a full body CT to check for occult disease (cancer mostly)) with contrast media. He is a good doc and I said OK although I did worry some about radiation..
Of course later I did research and determined my exposure from that series was likely ~5%-10% of the threshold dose for possible radiation sickness. ( These are slightly tricky calculations). I certainly think his diagnostic procedure was the correct call.
But knowing that Radiation Enteritis is a common symptom from exposure (although this can be the result of ingestion of short range emitters). I would call this overstated by an order of magnitude but acurate. Ten scans might do it.
Yes I am being a pain. But I was surprised at the level of exposure.
 
berkeman said:
Would you like to post some links to reputable medical websites that say that modern X-Ray imaging technologies (including CT imaging) "ionize the crap out of us"?
Better still, ultrasound.
 
berkeman said:
Would you like to post some links to reputable medical websites that say that modern X-Ray imaging technologies (including CT imaging) "ionize the crap out of us"?
I think that much of the not-unusual trepidation regarding excessive radiation exposure (not ionization) from medical X-rays comes from past days of longer exposures, e.g. with the dentist putting a lead blanket on your chest, and to this day, the operator goes behind a heavy shield before he does the zap, the reason being that if he didn't he'd get perhaps dozens of exposures per day; whereas, in general, the examinee gets only one or a few per year.
 
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  • #10
https://www.webmd.com/cancer/news/20040831/too-much-radiation-from-full-body-ct-scans
A single full-body CT scan gives a person a total radiation dose of about 12 mSv. That's close to the 20-mSv dose linked to cancer in Japanese survivors of atomic bombs. And each of these scans adds another 12 mSv to a person's total lifetime exposure. An mSv is a unit for measuring radiation dose.
This scan with and without contrast will be doubled i.e. 24mSv
https://www.cdc.gov/nceh/radiation/emergencies/arsphysicianfactsheet.htm
(mild symptoms may occur as low as 0.3 Gy or 30 rads)
This corresponds to 300mSv
So a big CT scan is not "nothing "

Of course the shoe store fluoroscopes in the late 1940's delivered more than 100mSv !
https://en.wikipedia.org/wiki/Shoe-fitting_fluoroscope

/
 
  • #11
hutchphd said:
Because of a weird , unpleasant, and acute (autoimmune) encephalitis five years ago my neurologist suggested I have a full body CT to check for occult disease (cancer mostly)) with contrast media. He is a good doc and I said OK although I did worry some about radiation..
Very sorry that you had to go through that. That full-body CT scan with moderate intensity levels and the bad accumulation for you sounds bad. Hopefully you got a second MD's opinion about if there were other diagnostic tests or a reduced scan that would give mostly the same results.
 
  • #12
The docs found nothing really treatable and they did nothing (except observe...as I said they were good docs) final diagnosis: Bickerstaff's Brainstem Encephalitis. I was improving at one week and very slight neuropathy at three months which seems permanent. Care was exemplary. And thank you President Obama for my insurance (the charge for 5 days hospital and many tests would have been $64k I paid a few hundred)
Thanks for your concern, but not really necessary. Some of the other Gillian-Barre Syndrome spectrum can be really unfun and a long slog. I was a very lucky dog.
 
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  • #13
Very good news. :smile:
 
  • #14
Astronuc said:
That is a cost to the buyer, either patient or insurance company.

The technology can be pricey as phinds indicated in his second post.There is the capital cost of the machine, which can vary widely ("typical prices range from $1 million to as high as $3 million for a single, state-of-the-art, high-powered MRI machine that can deliver the most detailed results"), then there is the operating cost (electrical usage and trained personnel), administrative cost, liability insurance (can be substantial for diagnosticians), salaries of doctors/nurses, and profit.

A neurologist recommended (prescribed) an MRI for my daughter. The cost was about $800, of which the insurance paid $640 (0.80 of customary). We found out after the fact that the doctor was a partner in the radiology group, so he was making some bucks on MRIs. In addition, we were told that the clinic did not do the full MRI, so we needed another MRI done. When the neurologist could not (or would not) give a prognosis, but recommended more tests, we went elsewhere.

My daughter's health and welfare was on the line, and I didn't care for the neurologist's attitude. Of course, I going to pay for whatever my daughter needs to be healthy, but I felt the neurologist was more concerned about making money than patient care.
That's horrible. I'm real sorry to hear that.
 
  • #17
Vanadium 50 said:
Better still, ultrasound.
I am amazed that ultrasound imaging has been used for decades in obstetrics yet it is only relatively recently that is has been used in other fields. In the 90s, I met a French GP who was 'pioneering' the use of ultrasound in geriatric medicine (at least a decade since U/S was used by midwives). Why doesn't every GP have a (very portable) U/S machine in the consulting room? In a ten minute appointment (almost), a GP could look at someone's gut without them even needing to put on a hospital gown?

It's possible to find out so much about the state of development of a foetus without any risk so why not look at the organs right alongside the uterus?

The above experiences of medicine in the United States are quite chilling (e.g. $800. Yet people complain about the UK Health service. What's the answer?
 
  • #18
sophiecentaur said:
Why doesn't every GP have a (very portable) U/S machine in the consulting room?
It is the same reason they don't have an X-ray installation in their office. One needs special training in the use and interpretation of the images for many of the applications. Ultrasound has been primarily used to assess structural/physical problems in organs (morphology) rather than tissue characterizations eg. the presence of gall stones, aneurysms, some solid tumors, organ size/shape, and blood flow. It is limited to the accessibility of the organ or region of interest as ultrasound has a limited range in tissue and does not pass well or is reflected by air or bone.
hutchphd said:
https://www.webmd.com/cancer/news/20040831/too-much-radiation-from-full-body-ct-scans
A single full-body CT scan gives a person a total radiation dose of about 12 mSv. That's close to the 20-mSv dose linked to cancer in Japanese survivors of atomic bombs. And each of these scans adds another 12 mSv to a person's total lifetime exposure. An mSv is a unit for measuring radiation dose.
This scan with and without contrast will be doubled i.e. 24mSv
https://www.cdc.gov/nceh/radiation/emergencies/arsphysicianfactsheet.htm
(mild symptoms may occur as low as 0.3 Gy or 30 rads)
This corresponds to 300mSv
So a big CT scan is not "nothing "

There is a misconception about the meaning of radiation dose. Radiation dose is a point function, the energy delivered to one gram of tissue. The biological effect depends on the integral of the dose over the irradiated volume modified by the susceptibility of the irradiated tissue. The effect of 1Sv of dose to bone marrow is many times different compared to that of muscle. The reference dose to which diagnostic studies are referred, the background radiation dose, is a whole-body dose. Most diagnostic studies that use ionizing radiation only expose a small part of the body so the biological effect is less.

The problems with US health care are several, Physician exposure to liability results in the overuse of diagnostic procedures and high insurance rates, poor management, frilly facilities, and free enterprise (charge whatever the market will bear).

Is health care in the US great?
https://healthsystemsfacts.org/?gad...ACUpiRIo9yiJdsRjndiVMsJww6kcEAecaAnyREALw_wcB
 
  • #19
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gleem said:
There is a misconception about the meaning of radiation dose.
I harbor no such misconception about ionizing radiation. A Sievert is a Gray modified by a dimensionless "Quality " factor depending on the radiation and for a dose D= 1 joule/kg $$Sv=QXD$$. A dose of 1 Sv will typically increase cancer risk 5% in the iradiated tissues
 
  • #20
gleem said:
It is the same reason they don't have an X-ray installation in their office. One needs special training in the use and interpretation of the images for many of the applications.
Unfortunately I'm getting some experience with this issue. I have an Achilles injury. Doctor ordered an ultrasound because the insurance company is a pain for getting an mri approved. But muskulo-skeletal ultrasounds are not common. The imaging center where I previously got a same day mri had a 3rd party provider for the ultrasound, that traveled. I had to email for an appointment. 2 week wait for the soonest appointment a 45 minute drive away.
 
  • #21
So much to say...

(1) Holy necropost, Batman!

(2) Comparison between national healthcare philosophies and systems belongs in GD, if at all. I do recall a study from the 90's where they added up all the health care that people wanted, and it was several multiples (6?) of the GDP. Since demand is greater than supply, someone is going to be unhappy - that's just math. "Who should be unhappy?" is a political question, and as such, belongs either in GD or nowhere.

(3) It takes time to learn how to properly administer an ultrasound. (And an x-ray for that matter) The equipment is more portable, which helps. But the level of skill needed to operate and interpret them is comparable to CT or MRI. It's a tool that can and often should be added to the toolbox, but it is not magic.

(4) The effects of low radiation doses are hard to measure. The LNT (linear no-threshold) model is the most conservative. Perhaps best from a perspective of prudence, but not for drawing conclusions. The data comes from three sources: post-WW2 Japan, which suffers from poor measurements of the radiation exposure; geographic differences in cancer rates, which suffer from many confounding factors; and nuclear vs, non-nuclear ship builders, which shows a negative effect - i.e. low levels of radiation are good for you (which nobody believes of course).

In most cases, the risk from running the test is smaller than the risk of not running the test.

(5) Different tests tell you different things. CT and PET have comparable radiation doses, but one tells you about anatomy and the other about metabolism. One is not intrinsically "better" than the other.

(6) Comparing costs is always complicated. If MRI costs 2x as much as an ultrasound, but ultrasound takes 3x as many scans to get the doc what she needs to know, which is more expensive?

(7) Cost to whom? I have a higher deductable for ultrasound than MRI. Does that mean ultrasound is cheaper or more expensive? One can spend a lot of time chasing one's tail on this.
 
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  • #22
The original MRI required both liquid nitrogen and liquid Helium for operation. Newer ones replaced the LN2 with a cryocooler and the very latest ones require no He2 replenishment. That may be a large part of the cost issue for smaller facilities.
 
  • #23
When considering the cost of a diagnostic study that may keep you out of the hospital consider the charge per day for an inpatient of more than $2500 on average in the US and the reduced risk of an untoward complication from that stay such as a medical mistake or sepsis.
 
  • #24
The nearest hospital runs its own cryo plant. I don't know its full capabilities. I suspect that their main product is oxygen and LN2 is a fortunate byproduct.

Just because you own the plant doesn't make it free, of course.
 
  • #25
It is free as air. (It is one of the best things in life). Of course the entropy reduction thereof requires energy so not free. It used to be said that LN2cost the same as milk and LHe2 the same as decent whiskey. Price of liquid Helium
Additionally I think the MRI itself uses about 10 kW so 10kW-hr per scan....a few dollars What are the coils and cores actually made of (I have no idea)?
 
  • #26
sophiecentaur said:
I am amazed that ultrasound imaging has been used for decades in obstetrics yet it is only relatively recently that is has been used in other fields. In the 90s, I met a French GP who was 'pioneering' the use of ultrasound in geriatric medicine (at least a decade since U/S was used by midwives). Why doesn't every GP have a (very portable) U/S machine in the consulting room? In a ten minute appointment (almost), a GP could look at someone's gut without them even needing to put on a hospital gown?

It's possible to find out so much about the state of development of a foetus without any risk so why not look at the organs right alongside the uterus?

I would hazard a guess that the resolution of ultrasound is inferior to MRI.

There are permanent magnet versions of MRIs that cost something like $10K USD. That makes them far more affordable (and portable) but they don't have the same resolution. So in many instances a doctor (fearing an error and perhaps malpractice) would naturally opt for the more expensive version.
 
  • #27
JT Smith said:
I would hazard a guess that the resolution of ultrasound is inferior to MRI.
My echocardiogram pictures (they let me see my heart working) seem to resolve axially to quite a bit less than 1mm. This is not too different from the 1mm value for MRI but we're not comparing the same things.
gleem said:
One needs special training in the use and interpretation of the images for many of the applications.
That's obviously true but I would reckon even a pretty ham fisted operator would do a lot better than a doctor palping someone's torseau when they come in with an internal pain or malfunction. In terms of bang per buck an ultrasound scanner would be very good value and give a GP a good idea about which expert to refer a patient to. They seem to be available from upwards of £2k; an almost trivial expense for a GP surgery.
 
  • #28
Astronuc said:
That is a cost to the buyer, either patient or insurance company.

The technology can be pricey as phinds indicated in his second post.There is the capital cost of the machine, which can vary widely ("typical prices range from $1 million to as high as $3 million for a single, state-of-the-art, high-powered MRI machine that can deliver the most detailed results"), then there is the operating cost (electrical usage and trained personnel), administrative cost, liability insurance (can be substantial for diagnosticians), salaries of doctors/nurses, and profit.

A neurologist recommended (prescribed) an MRI for my daughter. The cost was about $800, of which the insurance paid $640 (0.80 of customary). We found out after the fact that the doctor was a partner in the radiology group, so he was making some bucks on MRIs. In addition, we were told that the clinic did not do the full MRI, so we needed another MRI done. When the neurologist could not (or would not) give a prognosis, but recommended more tests, we went elsewhere.

My daughter's health and welfare was on the line, and I didn't care for the neurologist's attitude. Of course, I going to pay for whatever my daughter needs to be healthy, but I felt the neurologist was more concerned about making money than patient care.
This is one of those scenarios that makes me glad I live in Denmark where healthcare is free and ubiquitous (read: included in taxes). On the other hand I sometimes have the distinct feeling that our MRIs, CAT-scanners - what have you - are second-rate for the exact same reasons. I have little to no evidence though.

One horror-story is that the machine that they use to ionize cancer on Copenhagen teaching hospital sometimes fall out of "whack". A patient told me that. Private hospitals have been offering to undertake a lot of operations to bring down the waiting lists (the news here reported one guy who have to wait 12 years (!) for a jaw operation to alleviate his migraines so he can do his job.) but the state wont let them for some reason. They allowed them to handle perhaps 13 out of 100. Of course I only know what I read and see in the news but I'm sincerely doubting our little "socialist paradise" here....
 
  • #29
I've been MRI'ed multiple times, and ultrasounded multiple times. I am not a radiologist or other expert, but cannot tell you that one is obviously better than the other. I can tell you an MRI takes longer and covers more ground.

I don't think we are going to get a handle on what "more expensive" means. Is a bus more expensive than a taxi? The capital cost, sure. The cost per use? That's another story.

My last MRI was free. My last ultrasound was $8. (Out of pocket)
 
  • #30
The remarks below are based on a quick perusal of the web and 30 experience working with radiologists and radiological technologists.

Actually, the prices of MRI and CT scanners have come down dramatically for scanners that would be used in most hospitals being in the range of $300K to $500K although some specialized instruments can go for well over $1M. I think that this is largely due to the lowering of computer hardware costs from the eighties and nineties. During that time such computers were in-house systems like those made by DEC or Honeywell. Additionally, there is also the economy of numbers as well as the competition.

The life of a CT or MRI can be up to 10 years depending on advances in the technology or additions to services that may require more advanced features. Typically the cost of the unit and facility can be amortized in about two years with only operational costs thereafter.

Many hospitals have service and/or maintenance contracts with the manufacturer for CT and MRI in the range of about 15% of the purchase price per year. A tech (CT, or MRI) makes about $40/hr and usually there are two and maybe an aid. The radiologist may charge up to $100 to "read" a scan. On average about 20 MRI scans are done per day and 30 CTs. Radiologist salaries are in the range of $ 250K to $ 450K. Radiologists except at medical school-affiliated hospitals are usually not employed by the hospital AFAIK. A radiologist can read a scan in seconds in some cases but usually in a few minutes. Also, the radiologist must carefully read the patient's medical history to make sure the scan was done appropriately and also which may produce incidental findings not noted by the referring physicians.

Ultrasound units are usually well under $100K depending on the use and bells and whistles the buyer may need. An ultrasound tech makes about $40/hr. Interestingly Radiology many years ago lost control of US imaging which is usually done in the department of the specialty they are used.
 
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sophiecentaur said:
My echocardiogram pictures (they let me see my heart working) seem to resolve axially to quite a bit less than 1mm. This is not too different from the 1mm value for MRI but we're not comparing the same things.

Then perhaps I'm wrong about resolution. If I may hazard another guess or two I would suggest that perhaps they are not equal in terms of imaging certain tissues (guess #1) or through certain tissues (guess #2).

I'm less inclined to believe it's simply a scam to make money even as I am fully aware of the "radical cashectomy" procedure that is sometimes performed on patients (complete and total removal of all the patient's assets -- thank you Monty Python). Medicine is unfortunately a business and it makes sense to be wary of that. I could add a personal anecdote at this point but it isn't necessary. Advocate for yourself and be cautious.
 
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  • #32
JT Smith said:
I'm less inclined to believe it's simply a scam
A scam and a useful service are not mutually exclusive terms. Plenty of medics live very well on the proceeds of private medicine but that needn't detract from the useful contributions they make to people's lives.
But there are lot of companies which maximise shareholders' dividends and WE often pay them. In principle, the UK NHS is more restrained in what is spent and they do (sort of) have higher principles than some other health organisations.
 
  • #33
Yes, I understand that. As I mentioned I could have added personal anecdotes about unethical and fraudulent behavior by medical professionals that I have directly experienced. And no doubt MRIs are sometimes ordered when not necessary. But I would be very surprised if that means that we can replace them with ultrasound devices in the majority of cases. Why would people go to the effort of building simpler, less expensive, portable MRIs for remote or third world use if ultrasound was as effective in most cases?
 
  • #34
Just a friendly Mentor reminder to everybody to please avoid veering into political territory in this technical discussion. Thanks.
 
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  • #35
berkeman said:
That is a very inaccurate thing to say, IMO. Would you like to post some links to reputable medical websites that say that modern X-Ray imaging technologies (including CT imaging) "ionize the crap out of us"?
It's not gonna say it like that of course but CT scans can be equivalent to 3 years of background radiation. Not a huge deal if you just do one or two, but if you need to do a lot it's not great.
 
  • #36
JT Smith said:
Why would people go to the effort of building simpler, less expensive, portable MRIs for remote or third world use if ultrasound was as effective in most cases?

Two comments here. firstly, it appears that a portable MRI scanner can be ten times the cost of an ultrasound unit. Secondly, I can't find any references to portable MRI scanners earlier than 2023 - so it's new tech. Maybe, in a few years' time, things will be different.

Meanwhile, every (?) woman in the UK has access to an ultrasound scan and it can be done on a home visit. How many women are given an MRI scan for a routine progress scan? ultrasound has proved its worth. There is rightly a strong resistance to arbitrary changes in medicine but ultrasound is gaining ground in its use for examinations of soft tissue.

Maybe we'll get a comment from someone with real experience of imaging???
 
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  • #37
sophiecentaur said:
Maybe we'll get a comment from someone with real experience of imaging???

That would be best since neither of us really knows what we're talking about.

A quick perusal of the web suggests that ultrasound doesn't work as well when bone or gas filled organs are in the way. Probably it's more complicated than just that.

FWIW, I've had one MRI and one ultrasound, both at the same clinic. The MRI was for looking at my shoulder joint and the ultrasound was to examine organs in my abdomen.
 
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  • #38
AndreasC said:
It's not gonna say it like that of course but CT scans can be equivalent to 3 years of background radiation. Not a huge deal if you just do one or two, but if you need to do a lot it's not great.
What about at the dentist? I get one for my teeth/jaw every year.
 
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  • #39
sophiecentaur said:
Two comments here. firstly, it appears that a portable MRI scanner can be ten times the cost of an ultrasound unit. Secondly, I can't find any references to portable MRI scanners earlier than 2023 - so it's new tech. Maybe, in a few years' time, things will be different.
It depends on what you mean by "portable". Low-field MRI has been under development for quite a long time. Because the fields are lower they can be generated using normal magnets; meaning you remove the need for superconducting magnets. Even if the rest of the system requires cooling (because e.g., SQUIDs are used) this should be a substantial saving.
However, low-field MRI does not -as far as I know- have the resolution of regular MRI (there are some intrinsic limitation simply because lower fields mean lower polarisation). It might still be useful for some medial imagining, but last I heard (conference talk a couple of years ago) the "killer app" was no longer in medicine, but in explosives detection, that is for use in scanners of large items at e.g. checkpoints

I don't know how much of the cost of an MRI machine have to do with cooling. I suspect it is not nearly as much as people think. A "basic" 4K cryogenic system of the type that is used for MRI (with compressor and cold-head is something like £80,000 from Sumitomo or Cryomech; that is not very much compared to the cost of the whole system
 
  • #40
If somebody needs multiple full-body CT scans, they probably have more immediate problems than an elevated risk for cancer some years down the road.

By the same token, we could require ambulances to travel only on side streets at no more than 15 mph and obey all traffic signs and signals, to reduce the chance of an accident. But we don't.
 
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  • #41
Greg Bernhardt said:
What about at the dentist?
Your dentist gives you a full body CAT scan? Um..where exactly do you have your teeth growing?
 
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  • #42
sophiecentaur said:
I can't find any references to portable MRI scanners earlier than 2023 - so it's new tech. Maybe, in a few years' time, things will be different.
Portable MRIs are designed for small fields of view applications like the brain/ face, knee/ankle/foot or elbow/wrist/hand so their application is limited. These are low-field ( 0.065Tesla) devices and as such have poorer image quality.

Transportable whole-body MRIs for temporary use or as a rented instrument have been available almost from their initial clinical introduction. They can be fit into an ordinary house-sized trailer and moved and set up in a day. Rural hospitals often opt for such a service.
 
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  • #43
gleem said:
Transportable whole-body MRIs for temporary use or as a rented instrument have been available almost from their initial clinical introduction. They can be fit into an ordinary house-sized trailer and moved and set up in a day. Rural hospitals often opt for such a service.
That figures. You just can't get high fields without a big installation. It definitely comes under the heading 'transportable' . The cost would still be high.
The applications you mention are not so good for ultrasound.
 
  • #44
Greg Bernhardt said:
What about at the dentist? I get one for my teeth/jaw every year.
I found this:
https://www.francismccarthydmd.com/...radiation-risks-the-truth-about-dental-x-rays
At .005 mSv, the radiation you receive from the aforementioned dental x-ray is less than 1.6% of your daily background radiation exposure. You are exposed to the same level of radiation just from sunlight each day. Additionally, each x-ray is an individual dose rather than constant exposure, which is another factor in the cancer risks of radiation exposure. X-rays only increase the odds of dying of cancer by 1 in 2,000; compare this to the natural 1 in 5 chance you have of dying of cancer.
That's not as reassuring as they seem to want it to sound. 1.6% of background doesn't sound like a lot, but it's all focused on a very small area. 1 in 2,000 added risk of death is about the same odds as 500 skydives. That sounds like a lot to me. And is that per x-ray or total from 75 years of annual x-rays? Sounds like per x-ray.

There's also this:
The purpose of this review is to summarize the results of studies on of the association between exposure to dental X-rays and health risk....

In brain tumor studies, the association between dental X-ray exposure and meningioma was statistically significant in 5 of the 7 studies. In 4 of the 5 thyroid-related studies, there was a significant correlation with dental diagnostic X-rays. In studies on head and neck areas, tumors included laryngeal, parotid gland, and salivary gland cancers. There was also a statistically significant correlation between full-mouth X-rays and salivary gland cancer, but not parotid gland cancer. Health outcomes such as leukemia, low birth weight, cataracts, and thumb carcinomas were also reported. In a few studies examining health effects related to dental X-ray exposure, possibly increased risks of meningioma and thyroid cancer were suggested. More studies with a large population and prospective design are needed to elaborate these associations further.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6341170/

This is enough to make me wary of annual dental x-rays, but that's just me.
 
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  • #45
"More studies are needed" means "the effect is too small to see with the samples we have".

If 100% of people receiving dental x-rays developed oral cancer, we would know it immediately. If nobody (in a sample of N) got it, we'd know the probability was less than something like 3 or 4/N. You can't prove it iz zero.

As it stands, about 1% of the population develops oral cancer. The risk is ~5X higher in smokers. That sets the scale for how big a risk x-rays are: if it were much bigger than a fraction of a percent, we would already know. If it is a part per million, we probably wouldn't.

You know the lead apron you put on? It helps - but not for the reason you think. The number of x-rays it blocks isn't that different from the number that scatter back in. However, it minimizes patient movement, so it reduces the probability that you need to take a second set because the patient wiggled.
 
  • #46
However, you’re always exposed to ionizing radiation. On average, your body is exposed to 3.1 millisieverts (mSv) of natural radiation alone per year. At .005 mSv, the radiation you receive from the aforementioned dental x-ray is less than 1.6% of your daily background radiation exposure.
@russ_watters

Check the math .005mSv/3.1 mSv = .0016 = 0.16%
 
  • #47
Greg Bernhardt said:
What about at the dentist? I get one for my teeth/jaw every year.
A basic X-ray and a CAT scan are not the same! If you are getting the first, the dose is minuscule.
 
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  • #48
sophiecentaur said:
You just can't get high fields without a big installation
You can get to about 0.3 T with ferrites (permanent magnets) although 0.1 T is a lot cheaper and easier to find. You can get to 1 T with rare earth magnets, but I shudder to think of the cost.

My primary concern would be safety - that's a lot of field that you can't turn off. I would also want to see plenty of margin in the return yoke.
 
  • #49
gleem said:
Check the math .005mSv/3.1 mSv = .0016 = 0.16%
Yeah, they really bungled that, and it's worse than what you are saying. Googling around a bit, those are the numbers (they vary some, of course). But it's 3.1 per year and 0.05 per x-ray and they were looking for percent per x-ray compared to per day. .005/(3.1/365) = 0.59 (59% of daily exposure). It's less than an airline flight, but again, more concentrated.
 
  • #50
Vanadium 50 said:
"More studies are needed" means "the effect is too small to see with the samples we have".

If 100% of people receiving dental x-rays developed oral cancer, we would know it immediately. If nobody (in a sample of N) got it, we'd know the probability was less than something like 3 or 4/N. You can't prove it is zero.
It's trying to separate a weak signal from a strong signal. I get that that's difficult to do, but isn't very re-assuring to me either.

The 1/2,000 prediction appears to come from studies cited here:
Some studies have estimated the risk of radiation exposure from imaging tests based on the risks from similar amounts of radiation exposure in the studies of the atomic bomb survivors. Based on these studies, the US Food and Drug Administration (FDA) estimates that exposure to 10 millisieverts (mSv) from an imaging test would be expected to increase the risk of death from cancer by about 1 chance in 2,000.
https://www.cancer.org/cancer/risk-...ays/do-xrays-and-gamma-rays-cause-cancer.html

But that's the linear, no threshold model, which is itself somewhat controversial (which doesn't mean it isn't accurate).

[edit] And 10 mSv isn't 0.05 - different tests. That would seem to drop the risk by a factor of 200. Sorry, that first source wasn't good.
 
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