Radiation Limit

Has anyone ever heard that they are limited on the amount of radiation one receives on a particular area and/or tumor? Is SRS or Proton Therapy part of that radiation limit?

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I've heard this too. Apparently, the tissues can only take so much radiation in the same area. I believe SRS is part of this.

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hi, that is similar to the question i posed in another discussion. injury from SRS can be linked to dose and volume of radiation. and, since we are not radiation oncologists we need some help here. what are the safe limits and do you know of cases where this was breached, resulting in injury? thanks, raekel

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There is a limit to the rads you can 'safely' be exposed to in any one spot in your body. (A rad is a unit of absorbed radiation dose.) There is also a limit to the total number of rads you can be 'safely' be exposed to altogether (anywhere and everywhere in your body) throughout your entire lifetime.

Radiation is cumulative. Every kind of a treatment that exposes you to radiation and every different scan and test that exposes you to radiation each has their own safety limits of radiation exposure for the patient. The recommended 'safe doses' of radiation for each of these things, as well as the total amount of radiation (or rads) you can be 'safely' exposed to throughout your entire lifetime can vary according to your size, age and health. Unfortunately, not all medical centers pay strict attention to this. Guidelines and recommendations are continually changing regarding the amount of radiation it is safe to be exposed to.

There are even debates between experts about whether or not any extra radiation exposure, like in the scans that use radiation, should be avoided. Some opinions say you have to weigh the risks and benefits.

CT radiation exposure is such a case. Some experts feel it's the gold standard for VHL abdominal scans. For example: They feel CTs should always be used because we 'know' that unchecked RCC, is deadly and we only 'know there is a risk' the CT's amount radiation is bad for us. They feel we need to weigh the risk and benefits. Other experts feel MRIs are just as good or even better than the CTs and still others disagree.

I'm using CTs as an example because at one major center here in Michigan, it has only been in the recent years that they have started regularly using MRI for abdominal scanning in VHL patients under 18 years of age instead of CTs. It is interesting, because some European countries have been doing that for all ages for many years. Still, many prestigious centers here in the United States do not and are in disagreement with them. Even more interesting is the age criteria in some centers....for age 18 and under it's MRI for screening...over 18 it's CT. (I am 58 and know a lot of 18 year olds who are much bigger than me...makes you wonder why those particular centers don't work with a weight instead of age guideline.)

There is obviously a lot of debate between experts about how much radiation exposure is safe and how to determine the guidelines, or even if any exposure is safe at all. You can read about it, learn about it and go to conferences to hear about it. You can express your thoughts on it as a VHL patient (who needs regular monitoring and may get treatments which result in different degrees of radiation exposure) whenever you get the chance at conferences or in discussions with radiologists.

May is VHL awareness month. You can talk to newspaper and other media reporters about your concern with radiation exposure and maybe even get some extra information about VHL in a story. The more attention drawn to the issues and concerns with radiation exposure, the more the experts will look harder at it. The same goes for VHL.


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Fran's answer pretty much says it all. I had radiation on my brainstem and spine from C4-L7 or so to try to get rid of as many cysts/tumors/lesions etc as possible. It wasn't fun to say the least. In any event, the major growth was at C7 and that sucker didn't move an inch! Okay, in a game of inches which VHL pretty much is, let's say it didn't move a milimeter of a milimeter. About a year later when cyberknife really came into its own I was directed to go see a neurosurgeon about 3hrs north of where I live and I was told almost immediately that I couldn't have cyberknife surgery b/c I had my maximum dose of radiation for my life.

Talk about bummed out. At the time going through radiation was the best option but of course, looking back it probably would've been more beneficial to hold off or have less aggressive treatment b/c what the radiation did compared with what the cyberknife tech could've done for me was ridiculously different. The radiation got rid of "some" of the growths whereas the cyberknife could have gotten the nasty C7 bugger that has been a thorn in my back since '01 and the more traditional surgery which we're postponing as long as possible could very well leave me paralyzed.

And yep: maximum dose is different for everyone. It's a really tough choice. I find the "zapping" kinds of treatment to be so vast that it's just so hard to decide what is best for you. It really seems to be the one treatment that is truly individualized.

Good luck!

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My son has had two seperate treatments of SRS for brain tumours in the cerebellum, we have been told that they couldn't treat another tumour in that area because he has had so much radiation there already, the tumour we were looking at is very close to the place that has already had treatment. He is 21 years old.

I don't know if that helps at all!

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Thank you so much for all your responses. I'm still doing a lot of research on this and I will let you all know if I find out anything different. I guess I really want to know why there is a lifetime limit, what will happen if you go over that limit, if the limit is just for one area or all areas of the body, and if there are treatments that use less radiation and therefore you can do more of them. I just wish this was something that we were told at the very beginning of these kinds of treatments rather than later. Doctors need to be more upfront with this. The other issue I have is with all the other scans we have done, should we be counting this into the mix of radiation doses? I'm also a breast cancer survivor (non vhl related) I have to go for mammograms annually. What is this doing? I think I need to sit down and talk frankly with a radiologist! Thank you again for your posts and help in answer to my questions.

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I have had a few CT scans and proton radiation, all within a 7 year period. My Internist has replaced my abdominal CT scans with MRIs. Why expose me to radiation at this time, when later on in life I may definately need CT scans. It's like---save the exposure for when I really need it. My docs are at a VHL Clinical Care Center. Although, I still sometimes disagree with them.


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Okay, thank you for all the posts...all good information.
I keep track of how many CT scans my son has had, but what does that mean? How many is too many?
He is only 17 years old and already had 6 abdominal CTs as well as 2 MIBGs and one PET scan.
How does a doctor know you have had too much radiation? Is that based on information provided by the patient?

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How does a doctor know when you've had too much radiation exposure? That's a good question. There has to be specific guidelines or reference ranges. And just as Fran from Michigan stated---weight and body mass should be taken into consideration rather than age. These would be good questions for a Radiologist, or maybe an Oncologist. Also, there are different degrees of radiation. When I had proton therapy for my ocular angioma, I was in treatment with ocular melanoma patients. We all received five conseclutive treatments, except I received half the dose that they did. So, there are definately different degrees (or amounts) received per scan or treatment.


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Marie and others,
They are finding out that pediatric x-rays are more dangerous than adult x-rays because children are still growing. I talked with an epidemiologist and when I told her I had scoliosis, she told me that I must have been exposed to a lot of radiation as a child. I had broken my arm 3 times the first time when I was 2. So, yes I did have a lot of radiation as a child. I read somewhere that one x-ray on a child is equal to something like 10 x-rays in an adult. (I may have the numbers wrong, but I know its a lot more than if you were x-rayed as an adult) I'm still looking into this and researching, and as I said when I find out I will let you all know. I know it is taking a long time, but I just have so much on my plate right now. I'm happy we've gotten so many responses on this topic. Maybe we need to address this with the radiologist at NIH and get him to help answer our questions.

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We are publishing an article about diagnostic scanning in the May newsletter, so stay tuned.

This discussion has covered a lot of ground. Let me add a couple of points.

What happens when you have too much radiation is called "radiation poisoning".

For small doses (sunshine, airplane travel, diagnostic scans), see http://www.physics.isu.edu/radinf/qanda.htm

For radiation therapy (conventional radiation therapy or stereotactic (focused) radiation therapy, and nuclear fallout, see http://www.radshelters4u.com/index2.htm

For radiation poisoning (and a wealth of other aspects of radiation) see http://en.wikipedia.org/wiki/Radiation_poisoning

In the early days of stereotactic radiosurgery we saw a number of disaster stories where people were overtreated -- too large a tumor, or too many tumors etc. Do you really want to hear what it can do? Suffice it to say that people died, and it was not a pretty picture. With Dr. Oldfield from NIH we organized a symposium on VHL and stereotactic radiosurgery to begin to understand where SRS works best, and where the limits are to its capabilities.

No matter what machine you talk about, there are limits. A knife can be good or bad depending how you use it. The same is true for nearly every tool. SRS is a tool. We have to use it appropriately, and RESPECT ITS LIMITS. Believe me, you do not want to press the limits of this technology. Raekel is living with the fallout from a treatment that did not succeed. I was on a team that studied six cases where people died and two cases where people had experiences much like hers -- the first 5-6 months seemed to go fine, but then the symptoms began to rise and rose steadily for up to two years.

The doctors are not kidding you or being overly cautious. You do not want radiation poisoning. It is not good for your health.


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Ok then, here's another question. When doctors give you a radiation limit, do they take into consideration all these things? Some people are sun worshipers and some people avoid it like the plague. Some people travel all the time, some not at all. Some people have moved and don't always get their medical records so they aren't always sure "how much radiation" they've gotten, nor which tests they've received, or remember. Then there are people like me, who are older (I dare not say old!) and the radiation exposure back in the day was a lot worse than it is now. You also have people with multiple conditions who get scanned and x-rayed at different locations. There are doctors who order scans for everything and multiple times to fish for problems, and then there are those doctors who are more conservative. As I mentioned earlier, pediatric radiation exposure is so many times worse because of the smaller body and the fact that children are growing. Do they take that into consideration, or do they simply average it out and hope you were a healthy child not needing radiation for diagnoses? I'd like to pick the brain of an expert radiologist to answer all of these questions and more. Any suggestions? Thank you for the links to websites, but they don't go into these kinds of things. I'm just worried because I am now hearing so much about this and I feel I've been exposed to radiation more so than the average bear. They just started taking into consideration over exposure of radiation. You never even heard of it in the past. I just recently found out that the mammography machines now use much less radiation than they did years ago. I worry too about all the screenings I get and wonder if they are really necessary. I have metal rods in my back so MRI's are out of the question. I have to constantly weigh the risk of not finding something against the risk of radiation exposure. A person shouldn't have to constantly do this.

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I doubt they are counting anything other than therapeutic radiation (classic radiation treatments and SRS), not diagnostic radiation or the other kinds you mention (air travel, sunshine, etc.) They might use a "fudge factor" for those, but I'm sure there's no elegant calculation.

Best wishes,

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I had the opportunity to be in contact with a radiologist I greatly respect recently about the topic of determining the 'safe' amount of radiation exposure. Naturally, as a VHL patient myself, I have gotten yearly scans, and various other tests and procedures. So have my children. I am always interested in this.

He explained why it is hard to determine what 'safe' amounts actually are and how difficult it is to establish guidelines. He explained why it is so very challenging. Perhaps the following information he shared will help you understand why there are not a lot of easy answers with numbers and rules for some of your questions.

"Even the medical physicists argue among themselves about this topic. One problem is that the estimates of cancer induction are based on the Hiroshima bomb survivors - clearly a different group of people than those undergoing medical examinations.

We also don't know if there is a threshold, under which there is no
increase in cancer risk.

The most important thing is that patients should get the studies that are needed for their care. And secondly, the radiologists should perform those studies using the least amount of radiation needed.

There is a great deal of interest in the radiology community about this topic, and we have started a campaign called "Image Gently."

I looked up this campaign he referred to on the internet to learn more. You may find it very interesting to read about it. The focus is on exposure in children, but then they are more at risk than adults, so this is a good first step. It is apparent that there are many medical professionals trying to figure out the best and safest way to get the medical care and screenings we need and of course there are lots of yet-to-be- answered questions.

As science advances and more and more new radiation based treatments and scans are deveoped to save lives, so too more and more new questions on safety will be coming up.

For myself and my children I have decided that the best approach is to be sure any tests or any treatments we ever need are always done by only well respected medical centers with top- notch radiology departments who have the knowledge, interest, and finances to stay on top of the latest radiological information and techniques. They should be responsible enough to use the least amount of radiation possible.....not the tiny medical center down the road who has very few experienced radiologists and an expensive machine or two that they need to get paid off.

Care at a really good medical center (that's why we work so hard on the VHLFA ccc program), being advocates for our own care, and keeping well informed and educated about our disorder, when combined with a good medical team caring for us, helps assure we will be doing what is necessary for our health in the safest possible manner. So far the children and I aren't glowing in the dark yet.....(sorry, -humor always helps when we have to concentrate on so many stressful issues with no 100% answers.)

I know you have a lot of legitimate and serious concerns especially with all you have been through. The answers and information science and medicine has for us is frequently not able to keep up with the advances that are made. We need these advances. Yet we will continue to have justifiable fears because of the lack of answers. Nothing is ever simple. All we can do is keep trying to learn more, keep the doctors interested in learning more too, and keep doing our best to weigh the 'suspected risks' against the 'known benefits' for each aspect of our care. Hang in there.

VHLFA Michigan

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Reported today in Aunt Minnie, a site for radiology professionals (if you wish the registration there is free)

California regulators have fined a hospital where a 2-year-old boy sustained a massive overdose of radiation, receiving 151 CT scans in a one-hour period.

The state's department of public health has levied a $25,000 fine against Mad River Community Hospital in Arcata, according to an article by staff writer Cynthia E. Keen in our Pediatric Imaging Digital Community. State investigators believe the hospital failed to follow its own policies regarding radiation safety.


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Thank you all for your answers, research and help in trying to answer this question. A lot of this also boils down to the insurance companies. For instance, MRI's are much safer than a mamogram and are clearer and easier to detect changes in the breast. I know there are other tests that can be done that would be safer don't use radiation, but the insurance companies will not cover these expensive tests. I don't know what to do to change this other than writing to congress to get a bill passed. Insurance companies are in the business to make money and prefer we use the cheapest tests possible first. I wonder if we have reached our limit on radiation, if they would then pay for alternative tests. Well its been wonderful hearing all of these issues and answers, and I appreciate everyone's response. Perhaps we should consider asking for a different test to see if it is possible to have one without radiation. But I'll have to say, good luck with having the insurance company pay for it. We can always fight with them and try to get them to appeal, if enough of us do this, they may change their rules. Thank you again for all the posts on this topic. It is a big help, and gave me much food for thought.

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