GK radiation=???

[Upstate]

A friend was asking me about my GK experience and wanted to know how much radiation I received.  I told her 12 or 13 Gys., unsure of the exact amount, for 57 minutes.  She said "How much radiation does that equal-10 x-rays, 100, 1000"  I don't know the answer and am just curious, can anyone make a comparison of how much radiation it takes to kill an AN? (hoping anyway) Thanks.

Upstate

[Tumbleweed]

I once asked Dr. Chang for a comparison of CK doses vs those from X-rays. He said it was an apples-and-oranges type comparison that wasn't valid because an X-ray covers a much larger area of the body (thereby delivering more total radiation), whereas radiotherapy targets a much smaller area.

There was a fascinating thread about radiation doses a couple years ago on this forum. You can read it here:
http://anausa.org/smf/index.php?topic=14297.0

Best wishes,
TW

[Tumbleweed]

My directly preceding post notwithstanding, I have to say that the average X-ray does not produce 1.5 Gy (it's actually a lot less).

An antero-posterior skull X-ray produces about 0.03 mSv (millisieverts), or 0.00003 Gy. So by that measure, 12 Gy delivers 400,000 times the amount of radiation of an AP skull X-ray. However (and this is a huge qualifying factor), the volume of an irradiated tumor is a tiny, tiny fraction of that for an entire skull -- especially if the tumor is small- or medium-size. The difference between doses for X-ray and GK are probably more in the range of hundreds-of-X-rays equivalence for GK. Again, the link in my immediately preceding post gives more info on why the size of the treated area matters so much. (Kudos to PaulW and Marianna for pointing that out in that particular thread.)

To put this in a different perspective, if a person were to receive 200,000 AP skull X-rays at once (not that that's even possible), they would be dead within 14 days afterwards. GK delivers twice that amount of radiation, yet virtually nobody ever dies from GK (unless it's performed radically irresponsibly). That's because the high dose given is applied only to a very small area conforming to the location of the tumor.

Best wishes to all,
TW

[Jim Scott]

TW ~

I had a feeling my answer would be challenged - and so it was.  I probably shouldn't have attempted to respond to the original question because, apparently a comparison between GK and a typical X-ray is not really valid.  Thanks for your information.  My previous reply has been removed due to it's obvious error. I regret any confusion it may have caused. 

Jim 

[Tumbleweed]

No problem, Jim. I've been on the wrong side of the facts myself in the past, as the discussion in the link I provided will attest to. 

Best wishes,
TW

[jak1]

I found this extremely interesting to put things into quantitative perspective:

http://xkcd.com/radiation/

[Tumbleweed]

Thanks a lot for the link, jak1! Fantastic info.

For those who don't know, 1 Sievert is essentially equal to 1 Gy (1 Gray). A millisievert (mSv) equals one thousandth of a sievert, or 0.001 Gy. The mu symbol (looks kinda like a small u before "Sv") in the chart indicates 1/1000 of 1/1000 sievert (i.e., one millionth sievert, or 0.000001 Gy).

Best wishes to all,
TW