Dental X-Rays Linked To Common Brain Tumor 248
redletterdave writes "A new study suggests people who had certain kinds of dental X-rays in the past may be at an increased risk for meningioma, the most commonly diagnosed brain tumor in the U.S. Dr. Elizabeth Klaus, the study's lead author and a professor at the Yale School of Medicine, discovered that dental X-rays are the most common source of exposure to ionizing radiation — which has been linked to meningiomas in the past — and that those diagnosed with meningiomas were more than twice as likely as a comparison group to report ever having had bitewing images taken. And regardless of the age when the bitewings were taken, those who had them yearly or more frequently were between 40 percent and 90 percent higher risk at all ages to be diagnosed with a brain tumor."
Re:And it took this long to "make the connection"? (Score:5, Insightful)
Supposing this is true, it took this long because everybody thought that dental X-ray was harmless.
(tumor growth in less than 1:4.000.000 images, regardless of the type of tumor.)
Dental X-ray uses less than 0.01 mSv per image.
You absorb 200 times this amount every year, year in, year out. all your life. And if you live in a place with higher background radiation, this number goes up quickly.
So it is hard to prove these tumours are caused by the exams.
Lets wait and see what comes out of this.
Usually these kind of studies have some form of bias thats not adequately corrected for.
Re:not sure (Score:5, Insightful)
I'm a dental student, and I have been taught that - with modern equipment - exposure to radiation from 2 bitewings is about the same as half a day of ski holiday.
These comparisons are always misleading, because they ignore the density of the radiation received. Radiation from half a day of ski holiday is diffused over your entire body. The radiation from bite wing X-rays is concentrated on your teeth and skull. The concentration matters.
Let's use a better analogy. The energy at the focal point of a magnifying glass might be one-hundredth the amount of energy you get from standing out in the sunshine. But because that energy is concentrated into a small point, it will burn your skin.
We survive nature not because it isn't powerful, but because its power is spread out. That power gets dangerous when mankind focuses and purifies it.
Re:And it took this long to "make the connection"? (Score:5, Insightful)
Re:Cancer... (Score:5, Insightful)
I guess my question is how does the new tech affect people. If the old tech only doubled the tumor rate, reducing the amount of radiation by two magnitudes should lower your risk quite a bit.
Also, the machine at my Dentists doesn't do the whole head, but has a VERY focused output that pressed up against your cheek. You place a digital x-ray sensor between your teeth and it works as a "film".
They're like, "we don't even have to leave the room anymore". They stand right behind the machine.
Re:And it took this long to "make the connection"? (Score:5, Insightful)
The shit got modded +5 because...lo and behold...RF from a mobile phone is non-ionizing radiation. I agree that the term "radio waves" could have been better. But it would take tens of thousands of RF photons simultaneously striking the same exact electron at the same exact time to give it enough energy to break free from the atomic bond it has formed. It only takes one photon from an x-ray to do the same.
Go ahead. Do the math. Look up the energy it takes to ionize an atomic bond. Calculate the energy in an RF photon at 2.4 GHz. Calculate the energy in a photon of an dental x-ray (not sure what frequency they use). And then marvel at the four orders of magnitude between the two. I did this once, and maybe I should have saved a copy of the results so that I could paste it into the discussion every time some tin foil hatter thinks that 2.4 GHz "radiation" will give you cancer.
The primary mode of action for RF energy on biological tissue is in the form of heating. Just like your microwave. The electric field causes the dipole water molecules to rattle around, and the increased friction results in heat.
In fact, if you get an MRI, they make sure that for example your thighs are not touching each other. Because if they are, your flesh forms a loop antenna that can pick up the RF energy in the magnet room...which will cause localized heating and burns.
http://www.mrisafety.com/safety_article.asp?subject=17 [mrisafety.com]
"-Prepare the patient for the MR procedure by using insulation material (i.e., appropriate padding) to prevent skin-to-skin contact points and the formation of “closed-loops” from touching body parts."
Re:I've often wondered... (Score:5, Insightful)
X-Rays and other forms of ionizing radiation don't "bounce off" surfaces, it will either pass through, be absorbed, or trigger another particle to be emitted.
I assure you that all kinds of ionizing radiation can reflect. X-rays can reflect -- they make X-ray mirrors, usually out of highly-polished beryllium. It's more effective at small reflection angles (glancing reflection). You can even make X-ray fiber optics (glass light pipes), which is a decent way of focusing an X-ray beam. These again are only really effective for glancing reflections. Alpha particles and electrons also reflect.
Triggering another particle to be emitted is actually a subset of "be absorbed", although this isn't obvious. Photons aborbed by atoms regularly kick an electron into an excited state (or ionize it, the highest-energy excited state, in a sense). Electrons falling back into their ground states cause the emission of new photons with well-defined energies. I suppose you could also have a photon kick an electron into motion, producing a beta ray, but I don't think that occurs much in nonconductive bulk materials. (Usually you go the other way: electron beam to X-ray beam through brehmsstralung.)
There are 3 types of radiation that may be emitted, alpha, beta, and gamma.
Sort of. From nuclear sources. There are actually many more particles that can be emitted from particle decays, but those are the most common. More to the point, though, radiation sources used for X-rays generally don't emit alpha or beta particles. In fact, the term "X-ray" refers to a particular part of the electromagnetic spectrum. Gamma rays are electromagnetic radiation. (They conventionally referred to electromagnetic radiation within the energy range commonly emitted by radioactive materials. It's really preferable these days to call all such things "photons" regardless of their energy.) So, X-rays and gamma radiation are the same thing. Alpha and beta radiation are in no way relevant here.
However, putting a shield over the patient's head would only protect other people in the room, not the patient, because any such radiation would coming OUT of the patient's head.
That's only really true if the X-rays are well-collimated. Since they point the X-ray beam so that it goes horizontally through your head (more or less) and then give you a lead shield for your chest, it stands to reason that either the X-ray beam is not well-collimated or the lead shield isn't there to serve a functional purpose.