| Comparative radiation exposure |
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03/14/2013 00:52
stephenp 
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03/14/2013 00:52
stephenp
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Comparative radiation exposure
As I am considering a second round of RT I wanted to seek information on relative radiation exposure from a second treatment and the risk. I thought that I would share what I have found.
Background radiation is about 3 milliSieverts pa. This will vary depending on where you live, altitude etc
A dental x-ray is about 0.005 milliSieverts
A mamogram is about 0.4 milliSieverts
A 10 hour flight is about 0.05 milliSieverts ie about 10x a dental xray and about 1-2% of annual exposure.
Occupational exposure limits are around 20 milliSieverts pa
Radiotherapy for breast cancer is about 50,000 milliSieverts
Radiotherapy for DD is 30,000 milliSieverts.
However, radiotherapy is targeted.
In considering RT, the cumulative radiation risk must be considered.
Edited 03/14/13 03:06
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03/14/2013 01:17
callie 
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03/14/2013 01:17
callie
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Re: Comparative radiation exposure
The Dr. who did my RT said the exposure was so minimal that I could have it done again next year if needed.
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03/14/2013 02:15
stephenp
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03/14/2013 02:15
stephenp
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Re: Comparative radiation exposure
I will discuss this with the radiologist and report back. However the outcome was great for me so I will have it done again if I need it.
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03/14/2013 09:11
wach  Administrator
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03/14/2013 09:11
wach Administrator
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Re: Comparative radiation exposure
Stephen,
when estimating the risk of radiotherapy you also need to take in consideration what is irradiated. The hand is not extremely sensitive to irradiation, at least less than many other parts of the body (see e.g. http://www.dupuytren-online.de/downloads...20Dupuytren.htm).
Irradiating a previously untreated area of the hand is not an issue provided there is no overlap of the treated areas. The same area can only irradiated once, at the most twice. If you do it twice you get into the cancer dose which is already pretty high.
Wolfgang
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03/15/2013 20:50
JohnG
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03/15/2013 20:50
JohnG
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Re: Comparative radiation exposure
The radiation oncologist who is treating my hand told me that the risk of cancer is roughly "tenths of a percent." That's for my plan, which is the usual (ten treatments of electrons with 3 Grays per treatment, and a field that includes most of the palm plus about 1/3 of the fingers) and for my age (55 and male). I don't think he did any calculation for my case, so that was just a rough estimate of developing cancer sometime in my lifetime.
His estimate might be high, but it surely is not too low considering the Seegenschmiedt paper in 2012. Seegenschmiedt no observed cancers from 400 X-ray patients who were radiated with 21 to 30 Grays. That's after waiting from 60 to 160 months after treatment. So the risk from his X-ray treatment over that short time interval is at most 0.25%. I'm expected to live longer than that (another 324 months is the actuarial estimate for an age 55 male), so my risk is bigger, but I hope it can't be as high as 1%.
Most people assume the risk of cancer is proportional to the dose, i.e., doubling the total lifetime dose will double the risk of cancer. There's a debate over that, but it's what many people assume.
Edited 03/15/13 22:57
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03/20/2013 05:10
stephenp
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03/20/2013 05:10
stephenp
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Re: Comparative radiation exposure
I had a discussion with the oncologist today about the RT risk. I am 60 yrs old and the risk of developing a cancer in my life is 1/3. The risk of cancer as a result of RT is about 1/1000 although there is limited data. Hence the additional risk is very small. The oncologist did mention that the current data suggests that there is a higher risk from low level background radiation than from RT.
Incidentally I am commencing RT on 8th April based on the active DD and the early stage. This treatment is quite a lot earlier than for my left hand which I left quite late so I hope it is at least as effective or maybe better.
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03/20/2013 16:19
Tusk
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03/20/2013 16:19
Tusk
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Re: Comparative radiation exposure
callie:
The Dr. who did my RT said the exposure was so minimal that I could have it done again next year if needed.
callie, are you referring to another RT regimen totaling 30 Gy bringing the total lifetime to 60 Gy?
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03/20/2013 17:14
callie
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03/20/2013 17:14
callie
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Re: Comparative radiation exposure
Yes, 30 Gy at a time.
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03/20/2013 19:32
spanishbuddha Administrator
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03/20/2013 19:32
spanishbuddha Administrator
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Re: Comparative radiation exposure
callie:
The Dr. who did my RT said the exposure was so minimal that I could have it done again next year if needed.
This is a bit vague.
Also vague but a bit crisper ProfS in Hamburg told me another 15Gy (5 x 3Gy) on a previously treated area would be possible under certain circumstances.
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03/20/2013 21:27
stephenp
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03/20/2013 21:27
stephenp
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Re: Comparative radiation exposure
Thank you for that information, I did also discuss re-treatment of a previously treated site but without coming to a conclusion as it is not needed at this time. I suspect we are entering uncharted waters to some extent.
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