Years ago when my friends and I got into exercising we went to this vitamin store. I picked up this bottle that looked neat. The guy at the register asked if I was buying this for myself or for someone special. I told him for myself...He told me no matter how many I took it would never enhance my chances of getting pregnant. LOL...How was I supposed to now that!! I thought vitamins were vitamins...

Here it is from the L A Times

http://www.tampabay.com/SearchForwardServlet.do?articleId=945530

Just to give you guys more stories to tell, the microwave is not really a good comparison to radiation therapy. Instead tell them the radiation therapy is like millions of microscopic arrows being shot. Some arrows hit cancer cells, some hit good cells. The good cells are able to recover and rebuild, the cancer cells die.

Microwaves actually are radio waves (not ionizing radiation) and heat by the fact that the waves cause the molecules of food to bang into each other. (Essentially friction heating
)

The reason I like the microwave analogy is not the technical similarities (or lack of them), but because most people know that food instructions usually say to let the food sit after removing from MW to finish cooking. Sunburn is even better, however.

I can always count on those guts in RED to point us in the right direction.

Thanks Mark as usual.

One question though...are all the good cells hit by radiation arrows really able to recover and rebuild? I thought not?

Cripes, I never thought of myself as "a guy in red" .......

In layman's terms (the only ones I use), most of the normal cells are being replaced constantly by your body (they all have a finite lifespan). The idea is that cancer cells do not have the "time clock" for replacement. That is partly why they grow into tumors and masses. Radiation therapy is issued at a rate that will kill the abnormal tumor cells but not damage the normal cells faster than the rate at which they will naturally be replaced. So I should have said "the normal tissues recover and rebuild" as opposed to cells. In actual practice good cells are dying too. Sometimes the dose might be too much for some normal tissues and scarring might be the result. Certainly radiated tissues may not recover completely either. That is why we have so many "new normals" to deal with.

Now about that red thing....do you think we should be a different color?

I might add to Marks response that different cell types have varying times to recover as well. The red blood cells are replaced by the body every 120 days so the ones that are destroyed, passing through the carotid during RT, will get to anemic levels or close to it. The bone marrow is affected as well (mainly by certain chemos which affect white cell production) and takes a long rime to recover. Salivary glands, not directly in the beam field, take 18 months or more. Taste buds start returning in a couple of months but can take a year or more for more sophisticated taste sensation to return. Skin cells heal very quickly. Sometimes neck muscles are made fibtrotic by the radiation and never return to normal. (The fastest healing cells in the body are the cells in the cornea). The way that radiation (and most chemo as well) works, simply, is that it alters or damages the DNA in cancer cells so it can't replicate itself so it simply shrivels up, dies and is absorbed into the body (that's the theory anyway).

Another thing I might add is that a linear accelerator (LINAC), used for medical RT use, actually IS a gigantic microwave source that, when the beam is directed into a water cooled (usually titanium or tungsten) target, is transformed into high energy level x-radiation, anywhere from 6 MeV to 20 MeV (MeV = Millions of electron Volts), depending on the power source and penetration depth. Most OC is treated in the 6 MeV range.

One more thing, they don't measure dosage in "rads" anymore - that stopped decades ago. Like "cycles" were changed, in the 60's, to honor the scientist "Hertz", "rads" were changed to "Greys" (Gy, to honor the scientist "Grey") [100 rads = 1 Gy]. The maximum total dose rate, given to OC patients can range between 60-72 Gy. Anything beyond 66 Gy is considered a "boost" and is sometimes done to slam certain areas a little harder.

I also understand that the word rad was also changed to disassociate it from nuclear energy, as in the type, used in weapons and atomic bombs, and/or older cobalt 60 machines, all sources of "gamma" radiation. LINAC RT differs in that it is "ionizing" radiation and the LINAC must be on, and generating a beam, for radiation to be present. Gamma sources are always generating radiation (cobalt 60 machines are rarely if ever used in the US today but are still used in some 3rd world countries). The gamma source is simply controlled by mechanically moving 2 or 4 lead bricks (like doors or better, a variable aperture) on top of a lead box covering the radioactive source. The downside of gamma is that the source has a 1/2 life, so as the radiation loses it's potential, dose times must be increased. Often times this would result is many undesireable side effects, such as severe and permanent skin damage from the "dark" radiation found in gamma type sources.

RT is given in "fractional" doses, typically not to exceed about 1.8 - 2.0 Gy/day. If you were to be given the total dose rate at one time it would be lethal. This also determines how many treatment days you will actually have. Some new theories are being tested to split the dose into 2 sessions of .9 - 1.0 Gy. Typical treatment is 5 days a week with the weekends off. The daily dose rate was calculated on the bodys natural ability to repair healthy cell tissue.

These are the primary reasons that we say each patient responds differently to treatment and my responses listed above are generalizations.

Sorry to get so technical but I worked for the nuclear physicist who invented the Siemens LINAC and a beam bending technique that minimizes harmful radiation.

Hey go write a book

"Another thing I might add is that a linear accelerator (LINAC), used for medical RT use, actually IS a gigantic microwave source that, when the beam is directed into a water cooled (usually titanium or tungsten) target, is transformed into high energy level x-radiation,"

But the microwaves are not what is used in the therapy treatments, right?

The physics of the electromagnetic spectrum are facinating in how they behave (wave propagation etc) but it gets very hard to follow when you get to light spectrum frequency because you then have particles (photons) together with wave propagation. When you cross into quantum physics it gets even stranger.

I say all that because my intent was to clarify that microwaves are not themselves ionizing radiation (think particles). This is a common "urban" thought that is expressed all the time. We have all heard people say "nuking my sandwich" in the microwave.

OMG two men in red......

Technically what is accelerated are electrons. And these high energy electrons generate the x rays.

However ... how you accelerate them can be different...
(electrostatic, induction or RF (including microwaves))



M

"But the microwaves are not what is used in the therapy treatments, right?"

Of course not - or you would be cooked like a hot dog.

We had an instance where an institutions nuclear physicist, calibrating the machine, deliberately defeated the high dose rate interlock (which was interlocking because the target was burned out). The patients neck was subsequently "cooked" by microwaves and he died shortly thereafter. He complained that he could actually feel the heat... This is not an urban legend.

"Particles" are a tricky concept too. They are present in Alpha radiation which can be blocked by a Kleenex. There are no particles in ionizng or gamma radiation per say - they are photons within the invisible light spectrum.

"Charged particles" refer to Proton Beam Therapy, or PBT, which I will not cover here.

Markus,
the amount of x-rays is determined by the voltage, relatively low voltages can generate x-rays. CRT TV's typically have anywhere from 10-50Kv and thats why the use leaded glass in the tube face. They are almost always accelerated by high voltage DC.

For those DIY physics freaks - here is an x-ray machine you can build at home! http://www.dangerouslaboratories.org/xray1.html

Please note that OCF does not condone building your own x-ray machine and to do so is at your own peril and for entertainment purposes only. State, Federal and Local regulations may apply;-)

I never wear red...