Sobering article about radiation

[Tumbleweed]

Hi, everyone:

I found this online today: http://www.reuters.com/article/idUSTRE6BD69Y20101214?loomia_ow=t0:s0:a49:g43:r5:c0.023077:b40250990:z0

While the article was pretty vague about how many CT scans it takes to produce 'x' number of Gy (Gray) radiation dose, it gave me pause to consider what doses CK, GK and FSR deliver. The article, which is not a scientific treatise and therefore to be taken with a truckload of salt, says that Nagasaki survivors who received the highest dose of radiation received "more than one gray." My AN received the biologically equivalent dose of 11.5 Gy (6 Gy in each of three treatments) from CK. Healthy surrounding brain tissue received roughly 0.1 Gy.

It's important, however, to remember that this is an apples-to-oranges comparison. Nagasaki victims received radiation throughout their entire bodies, whereas CK delivers very thin beams of radiation targeted on a specific, relatively small area. And let's face it, it makes sense that the AN must receive a lethal dose, which survivors of Nagasaki by definition didn't receive (i.e., they have survived many decades later).

By extrapolation, however, the article gives a very general idea on how much radiation AN patients receive, in terms we can relate to a little better than by just saying this or that many Gray. I thought it would interest everyone here -- even though, like with me, it's bound to freak some people out a little.

Best wishes,
TW

[jerseygirl]

TW,

This is a great article since it shows that radiation is not as harmless as doctors and others would like us to believe. Neither is surgery, we know that also. However, both forms of treatments have a very low chance of killing a person as a side effect. AN is always fatal when left untreated. We have to keep things in perspective!

             Eve

PS. Both blood cancers (leukemia. MDS, etc) and AN can be caused by radiation as studies of atomic bomb survivors show. As part of my research for second surgery, I have seen a presentation by Dr. Friedman on youtube where he discussed just that. Unfortunately, I did not save it. If I find it again, I will post it, or if somebody finds it, please, post it.

[Joef]

avoid atomic bombs whenever possible...

[keithk]

When I had my consultation with the nerosurgeon he did not recommend radiation because he thought that it would introduce other problems down the road, like brain cancer. I lost a cousin to brain cancer several years ago and didn't wnat any part of that.

[sunfish]

If you're in your 20s or so, this might be more of an issue than for some of us who are "older."  I'm 51.  Long-term radiation effects might be less of a concern for someone with fewer years still ahead of them.

I like the "stay away from atomic bombs" quote!!  I also think that many of us my age and older were potentially exposed to all sorts of radiation sources in years gone by, before its negative effects were entirely understood.

[novagirl]

TW - thank you for posting this. I think it would be interesting to send the article to a radiation oncologist (perhaps post it on the CK forum?) and see what they say in terms of how this relates to AN patients. I do believe that targeted radiation as in case of CK/GK/FSR is very different from getting exposed to an atomic bomb explosion. 

I am one of the "younger" AN patients on here (34 y.o.), but I prefer to make my decision based on which treatment will give me the best chance of maintaining my current quality of life (in addition to getting the tumor controlled). That is why I am thinking of getting CK rather than surgery. I understand that there might be unknown side-effects showing up 30 to 40 years down the road, but who knows what else I'll be dealing with 40 years down the road.... Bottom line is - we don't know what the long-term effects of CK would be, it just hasn't been around that long. However, expert radiation oncologists like Dr. Chang for example very conservatively thinks that risk of getting cancer as a result of exposure to CK is 1 in 100,000 or even 1 in 200,000 (this is from his interview that Francesco posted recently on his website).  To put this number in perspective, 1 in 8 women in the US develop breastcancer in their lifetime.  I think we all as patients tend to bring our own life philosophies into our decision-making and certainly that affects how we ultimately make a decision about treatment. I just wrote this to make sure we do not scare newbies into thinking that radiation is not a good option for them.

[free2be]

Novagirl,

Not to add any fear factor here, but I don't believe the stat you quoted from Dr. Chang of the chance of cancer from CK is accurate. I have an e-mail from him stating it is 1 in 40,000 and I listened to Francesco's interview and remember hearing the same thing. In perspective, relative to breast, prostate, and colon cancer rates, it is still very low. My Mom died from brain cancer and so I was especially sensitive to this issue, but still had CK.

Connie

[luvzmutt]

I have not listened to Dr. Chang's interview yet, but wanted to add some information I was give.  I have NF-1 and an AN.  The AN is not related to the NF because it is unilateral, only on my right side.  On Friday I was at the NF Clinic at Johns Hopkins.  I met with Dr. Jaishri Blakeley.  She is an assistant professor of neurology, oncology and neurosurgery.  In addition to talking about my NF, we also spoke about "Justin Bieber", my annoying little AN.  She saw my MRI from July, and we discussed my possible treatment options, should it be that I have to leave "watch and wait".  She stated point blank that because of my NF, and my age (46), I cannot have radiation.  She told me that the chances for brain cancer after radiation are about 2%, but that my chances would be 5%.   

[novagirl]

Connie - yes, you are correct. Thank you for catching this. It's important to keep the facts straight! Dr. Chang quotes the probability of oncogenesis to be 1 in 10,000 to 1 in 20,000. He then states that OTHER DOCTORS when asked this question, quote 1 in 100,000 number. Basically, he is saying that the chances are infinitismally low. I am glad we are having this discussion since this is a concern that comes up for anyone looking into radiosurgery. I also wanted to share a short thread on the same subject that I started on the cyberknife forum over a year ago:

http://www.cyberknife.com/Forum.aspx?g=posts&t=2070#jumptobottom

Dr. Medbery quotes the probability to be 1/100,000.

Best wishes to everyone. Stay positive - there is life after AN!!!

[Jim Scott]

TW ~

Thanks for the link and the information, within. 

Radiation will always pose some degree of risk and I believe that most doctors and AN patients understand this but the better informed we are, the more intelligent treatment choices we can make.  However, I think the 'apples-to-oranges' comparisons in this and other non-scientific articles are unhelpful and simply make the radiation bogyman a little bit bigger and scarier with no real basis in fact.  It's a fine line between being duly informed of risks from radiation and getting frightened by scary comparisons of atom bomb victims/survivors and AN patients, which is the effect of the article, in my opinion.  As I see it, CT scans should be considered as a potential radiation risk but hardly something to lose sleep over.  As you stated in your post, unscientific articles such as these need to be taken "with a truckload of salt" or, in some cases, with a freight train of salt, that is, a good deal of skepticism.  I trust our forum visitors will do just that.

Jim     

[Tumbleweed]

Hi, Jim:

I agree with your points. I agonized a little about whether I should post a link to this article or not. The apples-to-oranges aspect might go right past some people and leave them lingering on vague radiation fears. But I decided to post this anyway because it's the first article I've read that gives us an inkling of how radiosurgery doses compare to anything else. A really poor inkling, but an inkling nevertheless.

I whole-heartedly agree with Novagirl's perspective. While I'd rather not have my brain irradiated, I think the risks are much smaller than many other I'm exposed to just by being alive over the years. And I'd rather have the highest quality of life I can now, while I'm still in my prime, rather than worry about what might happen 30 or 40 years from now. 30 or 40 years is a long time to live with the disabilities I would much more likely have had after micro-surgery, had I chosen that instead of CK.

I'm going to take Joef's advice, though, and stay away from atomic bombs. 

Best wishes to all,
TW

[PaulW]

One thing worth considering about the dangers of Radiosurgery is the volume of your tumour.
A 1cm Tumour in the Internal Auditory Canal has a volume of around 0.15cm3
A 3cm diameter tumour has a volume of 10.6cm3

You will need 70 times the total radiation to treat the 3cm tumour versus the 1cm

Treating a small tumour with radiation is far less likely to cause long term problems in comparison with a large tumour.

[Tumbleweed]

Paul, I think you meant to say that the same dosage is applied over a larger area, for larger tumors. The dosage, in fact, doesn't change with tumor size.

The radiation is applied in a "cloud" shape to conform with the shape of the tumor, in order to kill every bit of it (hopefully). So it makes sense that it would be applied over a larger area. It is true, however, that any cranial nerves that are "in the way" will also be irradiated. So, yes, more collateral damage will happen to normal cranial-nerve tissue with larger tumors than with smaller ones. That's the price one pays for having radiosurgery.

But having said all that, I think it's misleading to say it takes "70 times the total radiation to treat the 3cm tumor versus the 1cm." For both sizes -- and for all tumor sizes in between, smaller or larger -- the typical "amount" of radiation applied is roughly 11.5 to 13 Gray. The dosage does not vary with tumor size.

Sincerely,
TW

[mk]

Interestingly, I happened to chair a Master's thesis defense from the oncology department last week, which dealt with the manufacturing of dosimeters that can be used to estimate the amount of radiation that is actually delivered to cancer patients. This test is done while planning the treatment, and before the actual delivery, to make sure that the radiation dose is uniform.

Obviously I read the thesis with much interest, as it contained many interesting definitions.  So the definition of a gray is the amount of ionizing radiation, in Joules, delivered per kg of mass. In other words, 12 Gy of radiation would be equivalent to 12 Joules/kg of mass (1 kg = 2.204 lbs for our American friends). As mass is of course related to volume, the total amount of radiation received would be then dependent on the volume of the tumor.

Copying from Wikipedia: "A whole-body exposure to 5 or more gray of high-energy radiation at one time usually leads to death within 14 days. This dosage represents 375 joules for a 75 kg adult" This explains the article that TW found, about the radiation exposure of Nagasaki victims. If you deliver 5 Gys to the whole body (say 75 kgs), this is a hopping 375 Joules. But if you deliver 5 Gys to a tumor, say of 10 ccs (which I will assume that is equal to 10 grams or 0.01 kg), this will amount to 5x0.01=0.05 Joules. So it all depends on the weight of the tissue being radiated.

For comparison, again from Wikipedia, "For curative cases, the typical dose for a solid epithelial tumor ranges from 60 to 80 Gy, while lymphomas are treated with 20 to 40 Gy. Preventive (adjuvant) doses are typically around 45 - 60 Gy in 1.8 - 2 Gy fractions (for Breast, Head, and Neck cancers.)"

One more thing: In radiotherapy, we are talking about "ionizing" radiation, which is radiation that during an interaction with an atom, it can remove tightly bound electrons from their orbits, causing the atom to become charged or ionized. This can come from many sources, like gamma rays (from a Cobalt source), X-rays, etc. Radioactivity (say from an atomic bomb) also results in radiation, but of course obviously with much more detrimental effects.

Sorry about the technical post, but this is fascinating, and also the source of confusion, so it is important to have the scientific facts.

Marianna

[Tumbleweed]

Thanks so much for your post, Marianna. It would seem that Paul was correct and I was mistaken. That is, the larger the tumor, the greater the amount (in joules) that the tumor (and any healthy tissue that's in the way) receives. (Sorry, Paul, for suggesting otherwise.)

Marianna, is the radiation from an atomic bomb then not ionizing radiation? And what is the salient difference, in terms of effect on the body, of ionizing versus other types of radiation?

Fascinating stuff.

Best wishes,
TW