Physics for Dummies
AKA
Xray Mythbusters!!!!!
OK, this post is meant for EVERYONE...the hopeless people of the general population and the hospital staffers as well....Everyday almost, I am approached by someone, be it a coworker, a friend, or a patient who has something silly to say about xrays, so I decided it was time for a little physics 101 class for anyone who is interested. I am not a Ph.D. ..... yet..... :) but I do have a VERY good grasp of radiation physics, exposures, and biological effects of radiation....and I just feel that if i dont share this info.....eventually, someone will succeed in dragging me over Stupid Gully with them. Not to sound too uppity, because before school I had no clue either, but now that I do, I'm gonna share the wealth. So sit back kids and put your thinking caps on...I'm about ready to explain xrays and radiation so that a third grader could comprehend it....so you might learn something new (wouldn't that be GREAT?)
First, what is an xray?,.... good question, it starts with a piece of "tungtsen (a metal) wire" and we heat it soooo hot that it glows, well, my friends, that glowing you see on any orange hot metal is called thermionic emmision....it simply means electrons are being expelled from the metal.....we concentrate these electrons and all at once bombard another piece of tungsten with them at the same time..... when this happens, many different kinds of reactions occur...heat...vaporization, but also, some of them with the highest energies, get converted into xray photons, which simply means the electrons are absorbed by this second piece of tungsten, but they have such a high energy (and energy can neither be created nor destroyed, only converted) that something kind of explodes from this second metal, and that wavelength is higher than electrons, and we call that an x-ray photon.... because the guy who discovered them didnt know what the hell he was looking at.... "X" being a variable.
Second, how does it make a picture....it's just like the film in a camara....where a shutter opens up and records the different amounts of light that enter through the window...just think of those films in xray like the shutter and film in a camara, xrays are emitted for usually less than a eighth of a second and that little burst is what is picked upon the film..bones look white because when that burst was emitted, the bone was dense enough to "stop" the xrays, where as fat and the air around your skin don't hardly slow it down or stop anything at all, so they look black, and muscle and organs, well...they're kinda in between, so they look grayish...not too hard at all is it kiddies?
Now, some preconceptions about xrays themselves,and our professions as a whole.
1. When we ask you to step out of the room while we xray someone else, it is not because of the radiation you would get, but more because the laws state that we can't radiate anyone without a physicians order. If they order an elbow xray and your hand hurts, i cant just take a picture of your hand to be safe, i have to go ask the doctor myself if i can add it on.... red tape, but very necessary with some of the idiots that get xray licenses.
2. Radiation does not linger....when we talk about radioactive materials, that's a whole 'nuther ball games, a radioactive particle is nothing more than a bunch of very unstable atoms we created and suspended in some solution like saline and they are slowly "decaying" or breaking down and becoming stable again..... that is what a radioactive half-life is, the amount of time it takes to become half as radioactive, and half as dangerous to us... radiation, as in x-rays..... they travel at about half of the speed of light...which is booking it.... once they get ejected they just go until they hit something..they either go through it, or they get stopped, they can't bounce off and change direction, they can't go around corners, they can't seek out the body...they just go in a straight line until acted upon. That's why we put those lead aprons on you when you get an xray, no need to wrap you up or anything, just put metal inbetween you and the xray and you get no radiation.
3. If there is an xray room beside you, no...you are not getting exposed to radiation by sitting in a chair outside the door.. the rooms that house xray epuipment are lead lined, with a minimum of 1/16th inch of lead or some sort of lead equivalent, like mortar..if you have 4 inches of mortar, you don;t need lead...
4. You get more radiation by going to the beach all day than you do if you get a chest xray....and yes, it is the same type of radiation, but a lot of it is more dangerous....think about it, remember above when i pointed out the electrons boiling off of orange hot metal, what do you think the sun is?....a boiling ball of gas emitting electrons as it slowly over 5 million years burns out. but instead of traveling 5 feet through air to hit you, these travel from the sun to hit you.....and through layers of atmosphere and clouds, so you can see how these would be more damaging.... so, don't be so afraid of a chest xray, be afraid of the damn beach.
5. Xrays will not make you glow in the dark... the reason this came about is because certain radioactive compounds, see above about half lives and such, can react with certain elements to fluoresce...or give off light...the majority of these elements will emit a green light, some blue and a couple purplish, but that is not xrays that is radioactive material.... xrays do use the same concept though, the inside of those xray cassettes you see, if you open them up, they look white on the inside, what happens is when that burst of xrays hit the outside of the screen ( the film is inside in the dark because it is ruined by light) the white layer is acutally a bunch of crystals that give off light. The reason you get almost no radiation anymore is because now instead of just letting the xrays create the image, we let one xray photon, hit a big crystal of light and then the light makes the image, not just a tiny tiny tiny little xray photon.....so......no glowing from over exposure, no matter how much radiation you receive....
which brings me to my last and final point....why you should be scared of radiation and what effects it can and will have on you.
there are two types of effects genetic and somatic(anything but genetic) the somatic effects are the things like getting luekemia....they have found a higher incidnece of luekemia with radiation exposed populations than not...but we're talking the japanese after WWII or the employees of chernobyl....the major radiation disasters. Cateracts they have found have occured in radiation WORKERS at an earlier age than non workers, but they have not found a higher rate of cateracts, just that they effect those people earlier... Also, you can lose your hair or get red shiny skin, both of which occur at levels we couldn;t produce with our dinky machine if we tried.....
The genetic effects especially on females are the things to worry about. The reason we have to do a pregnancy test on any female of child bearing age before taking an xray is because we don;t know enough to know what the minimum amount of radiation is necessary to cause gentic mutations...so we say better safe than sorry, if you could be pregnant, we're not xraying you...only exceptions being if you sign a waiver stating you are not pregnant or in an emergency situation where the benifits of finding out what is going on outweighs the risks of something happening. Also, the younger the baby, the most sensitive they are, so if you are only 4 or 5 weeks, we are more concerned than if the baby is already developed and you're going into labor tomorrow. Also, females have a set number of eggs we are born with, no more, no less....so if we radiate them enough to cause harm, or worse yet, destroy them, we have no more...hence the term radiation sterility.....now in men, you produce more sperm by the second, and the damaged wounded ones will simply die out and healthy ones will take their place. No retarded radiated sperm is going to magically make its way to the egg and create a retard child on its own. The only thing radiation effects that matters is our DNA...when it hits and kills a cell big deal, we kill and replace cells in our body by the second, and there actually is a theory called radiation hormesis that says that a small amount of radiation is actually good for your body's natural metabolic process. DNA is the "target molecule" when it is hit by an xray, mutations can occur and then in turn, change or inhibit the growth and development, that;s why pregnancy is the problem, its the time with the higher growth rate. The biggest thing is that some of these gentic effects might not surface until 2 or 3 generations later, such as luekemia, now, children and grandchildren of atomic bomb survivors are seeing the effects the radiation had on the DNA and reproductive organs.
So....do you feel more informed, more comfortable with xrays? Any question you can think of, ask me....I mean, radiation related of course..... this isn't Ann Landers....
