Here is a great link to an article by Don Miller M.D. on why radiation is helpful, not dangerous.
http://www.donaldmiller.com/Afraid_of_Radiation.pdf
Wednesday, September 13, 2017
Saturday, February 9, 2013
The ongoing CT debate
Slow day and a slow night at work. Found some articles worth posting and comments.
This is a brief comment from Dr. Elliot Siegel about the proposal by some to require informed consent for the radiation exposure associated with CT.
Dr. Siegel's comments
Personally, like the recording of every dose, I think requiring a signed informed consent unecessarily exaggerates the risk of the radiation. I particularlly like his comment about the use of the LNT based Japanese survivor studies, which assumes all delayed toxicity from a nuclear explosion is due to radiation. I believe this is another bias of the BEIR reports, which are done by radiation protection specialists.
Just this month an interesting, and very relevant study came out of Harvard showing that the riks of cancer from CT scans in young adults is far less than the risks of the diseases for which the scans were done. This type of study makes far more sense to me than just using the LNT to calculate inflated risks. And, the Harvard study uses CT risks based on the LNT, which means the relative risks of the CT scans is even lower than the study suggest.
press release for Harvard study.
Here is a study about the risks of radiation induced cardiovascular disease. This study looks at multiple radiation studies previously published, including low dose exposure in radiation workers as well as the Japanese survivors.
cardiovascular disease
I find this paragraph particularly interesting.
"Most of the studies considered in the present review involved low-to-moderate mean cumulative radiation doses (≤ 0.2 Gy), with participants in the occupational studies exposed at near-background dose rates. Nevertheless, the small numbers of participants exposed at high cumulative doses (≥ 0.5 Gy) drive the observed trends in most cohorts with these higher dose groups."
In other words, if you take out the data from the Japanese bomb victims, the data really is weak. Here again the assumption is that all delayed toxicity and morbidity from the explosions is due to radiation, ignoring all the other effects of an atomic bomb.
Here is an excellent discussion of why the LNT is no longer a reasonable assumption when assessing radiation risks. This is not to say there is no risk, just that the risk is not linear, and very low compared to other risks in our daily life. (see page on Risks.)
Paper on LNT from Radiology.
Here is a companion article in the same issue of Radiology giving the opposing viewpoint, that the LNT is the best we can do in assessing radiation risks at low levels.
Paper defending the LNT in Radiology
My favorite line in this paper, " Just because one cannot detect a risk does not mean that it is not there."
The question here for me is, what is the goal, and at what cost? The proponents of the LNT want us to go to great extremes to protect the population from the very small risks of low dose radiation. The anti-nuclear energy folks want us to burn more fossil fuels and polute the environment on a daily basis, to avoid the miniscule potential risk of radiation exposure. If the goal is to save lives, just lower the national speed limit to 25 mph. This will save lives and energy. Plus, it is free and good for the environment. Or better still, have the government stop subsidizing and promoting our high carb, low fat/protein diet, which has been clearly shown to be the major factor in our national epidemic of obesity, diabeties, metabolic syndrome and heart disease.
But, the goal here is not to save lives. The goals here are far more complex, and complicated by multiple factors. As always, the biggest single factor is money.
Radiation protection is a multi-billion dollar industry. The fact that every life saved costs millions of dollars is not seen as a problem to those within the industry. Environmentalists raise lots of rent money capitalizing on radiation phobia, so no radiation is safe. And, both the food industry and the transportation industry are major forces in American economics and politics. They will not willing accept changes which cost them money .
This is a brief comment from Dr. Elliot Siegel about the proposal by some to require informed consent for the radiation exposure associated with CT.
Dr. Siegel's comments
Personally, like the recording of every dose, I think requiring a signed informed consent unecessarily exaggerates the risk of the radiation. I particularlly like his comment about the use of the LNT based Japanese survivor studies, which assumes all delayed toxicity from a nuclear explosion is due to radiation. I believe this is another bias of the BEIR reports, which are done by radiation protection specialists.
Just this month an interesting, and very relevant study came out of Harvard showing that the riks of cancer from CT scans in young adults is far less than the risks of the diseases for which the scans were done. This type of study makes far more sense to me than just using the LNT to calculate inflated risks. And, the Harvard study uses CT risks based on the LNT, which means the relative risks of the CT scans is even lower than the study suggest.
press release for Harvard study.
Here is a study about the risks of radiation induced cardiovascular disease. This study looks at multiple radiation studies previously published, including low dose exposure in radiation workers as well as the Japanese survivors.
cardiovascular disease
I find this paragraph particularly interesting.
"Most of the studies considered in the present review involved low-to-moderate mean cumulative radiation doses (≤ 0.2 Gy), with participants in the occupational studies exposed at near-background dose rates. Nevertheless, the small numbers of participants exposed at high cumulative doses (≥ 0.5 Gy) drive the observed trends in most cohorts with these higher dose groups."
In other words, if you take out the data from the Japanese bomb victims, the data really is weak. Here again the assumption is that all delayed toxicity and morbidity from the explosions is due to radiation, ignoring all the other effects of an atomic bomb.
Here is an excellent discussion of why the LNT is no longer a reasonable assumption when assessing radiation risks. This is not to say there is no risk, just that the risk is not linear, and very low compared to other risks in our daily life. (see page on Risks.)
Paper on LNT from Radiology.
Here is a companion article in the same issue of Radiology giving the opposing viewpoint, that the LNT is the best we can do in assessing radiation risks at low levels.
Paper defending the LNT in Radiology
My favorite line in this paper, " Just because one cannot detect a risk does not mean that it is not there."
The question here for me is, what is the goal, and at what cost? The proponents of the LNT want us to go to great extremes to protect the population from the very small risks of low dose radiation. The anti-nuclear energy folks want us to burn more fossil fuels and polute the environment on a daily basis, to avoid the miniscule potential risk of radiation exposure. If the goal is to save lives, just lower the national speed limit to 25 mph. This will save lives and energy. Plus, it is free and good for the environment. Or better still, have the government stop subsidizing and promoting our high carb, low fat/protein diet, which has been clearly shown to be the major factor in our national epidemic of obesity, diabeties, metabolic syndrome and heart disease.
But, the goal here is not to save lives. The goals here are far more complex, and complicated by multiple factors. As always, the biggest single factor is money.
Radiation protection is a multi-billion dollar industry. The fact that every life saved costs millions of dollars is not seen as a problem to those within the industry. Environmentalists raise lots of rent money capitalizing on radiation phobia, so no radiation is safe. And, both the food industry and the transportation industry are major forces in American economics and politics. They will not willing accept changes which cost them money .
Friday, January 18, 2013
Much ado about (almost) nothing
In the June Lancet Dr Mark Pearce, et al. published an article, "Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumors: a retrospective cohort study." full article and a comment.
In the November issue of Radiology, Drs Brenner and Hall, both radiation physicists of some renown, published an editorial referring to this article entitled, "Cancer Risks from CT scans: Now that we have the data, what next?" full editorial
It is a catchy title for an editorial, but the problem is we still don't have the data. The study by Pearce, et. al. compares the long term followup of children who have no CT scans vs kids with a low number of CT scans vs kids who have several CT scans, and looks at the incidence of brain tumors and leukaemia. It is a large study with some 180,000 children included. What is not included is why they got imaged in the first place, as this could not be extracted from the database. They conclude, and of course Drs Brenner and Hall agree, that the CT scans caused the tumors. What they actually proved is that kids who require multiple CT scans are sicker kids.
Every physician with any experience knows that some people are just more disease prone. In the old days of film radiology, these were the patients with the thick jackets. Now they are the patients with the long problem lists in their electronic medical record. When I was an intern we called it PPP (piss poor protoplasm.)
The study retrieved data from national registries on children who had CT scans before the age of 22. They then retrieved data from cancer registries for two diagnosis, leukemia and brain tumors. They did not look at other diagnosis.
I would be willing to bet there is a long list of diagnosis which are statistically different in the three groups. They need to analyze the data for the incidence of things like intestinal disorders, pneumonia and chronic pain in these children down the road. No doubt these problems are more frequent as well. Did radiation cause them all? They want to believe the CT scans caused the cancer, but they have used selection bias to divide their study groups.
Just another example of researchers wanting to support their preconceived beliefs.
In the June Lancet Dr Mark Pearce, et al. published an article, "Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumors: a retrospective cohort study." full article and a comment.
In the November issue of Radiology, Drs Brenner and Hall, both radiation physicists of some renown, published an editorial referring to this article entitled, "Cancer Risks from CT scans: Now that we have the data, what next?" full editorial
It is a catchy title for an editorial, but the problem is we still don't have the data. The study by Pearce, et. al. compares the long term followup of children who have no CT scans vs kids with a low number of CT scans vs kids who have several CT scans, and looks at the incidence of brain tumors and leukaemia. It is a large study with some 180,000 children included. What is not included is why they got imaged in the first place, as this could not be extracted from the database. They conclude, and of course Drs Brenner and Hall agree, that the CT scans caused the tumors. What they actually proved is that kids who require multiple CT scans are sicker kids.
Every physician with any experience knows that some people are just more disease prone. In the old days of film radiology, these were the patients with the thick jackets. Now they are the patients with the long problem lists in their electronic medical record. When I was an intern we called it PPP (piss poor protoplasm.)
The study retrieved data from national registries on children who had CT scans before the age of 22. They then retrieved data from cancer registries for two diagnosis, leukemia and brain tumors. They did not look at other diagnosis.
I would be willing to bet there is a long list of diagnosis which are statistically different in the three groups. They need to analyze the data for the incidence of things like intestinal disorders, pneumonia and chronic pain in these children down the road. No doubt these problems are more frequent as well. Did radiation cause them all? They want to believe the CT scans caused the cancer, but they have used selection bias to divide their study groups.
Just another example of researchers wanting to support their preconceived beliefs.
Sunday, December 9, 2012
Last week I attended the annual meeting of the Radiologic Society of No America, in Chicago. This is the largest annual medical convention/trade show in the world. It is the place to be if one is interested in learning about radiation in Medicine. I go every year.
This year the society hosted a very interesting mock malpractise trial. It was very informative about the workings of such a trial for those who have never been through one. For me, it was scary, because I see what a Pandoras Box radiologists are creating as we feed our nation's radiation phobia.
The plaintif in the case was a young father, who's wife had died at age 33 with breast cancer. 10 years prior to the diagnosis of her breast cancer, the wife had several episodes of chest pain over an 18 month period. During that time she had 6 visits to the ER, and each time a CT was done to exclude pulmonary embolism( potentially lethal blood clots in the lungs.) The plaintif was suing the radiologist who read the exams, because he never once mentioned the potential for carcinogenisis which might be associated with low dose radiation. (They estimated the total dose around 200 mSv) He was not claiming the radiologist misread the CT scans, just a failure to warn about the risk, which he felt contributed to his wife's death from breast cancer.
The trial featured two expert witnesses for each side, a radiologist and a medical physicist. A real judge presided, and real lawyers argued for both sides. The jury was a group of volunteer laypeople, unfamiliar with the case. Interestingly, when the jury was away "deliberating", their discussion was broadcast to the audience.
I find the case alarming because it ended in a hung jury. 7 for the defense, 5 for the plaintif. This is disturbing for several reasons. First, these sounded like intelligent people, and yet 5 of them actually thought there was reasonable evidence that the CT scans contributed to the womans's breast cancer. Second, one of the key defense arguments was that 10 years ago, discussing potential radiation risks was not the standard of care, while today it is being debated that it should be.
The last five years has seen a surge in articles about the potential risks of radiation from CT scanning, written by both radiologists and non-radiologists medical professionals. All of these articles use the Linear no threshold theory (LNT, see my page "A radiobiology primer" for an explanation) to calculate highly inflated and alarming numbers about the risks of these scans. They tend to ignore the fact there are many places in the world with background radiation levels in excess of 150 mSv per year (our back ground level is 3 mSv, so this is the number the articles like to use as a baseline or "normal" level). In these areas every man, woman, child and fetus recieves a dose equivalent to 5 or 10 CT scans a year, with no ill effects. In fact, in some of these areas the average lifespan is longer than ours.
They also seldom mention that no one has ever shown a genetic or carcinogenic effect in adults from low level radiation. Quite the contrary. British radiologists were closely monitored for nearly 100 years in terms of their radiation dose, diseases and life span. In the early years of medical radiation, large doses were common. Since 1955, radiologists have received lower doses (still higher than non-radiologists) with no measurable ill effects. American shipyard workers building nuclear powered ships were closely monitored in a similar manner. The study was considered "negative" because they also lived longer and had less cancer than non-nuclear shipyard workers. It wasn't "negative". It showed the positive effects of radiation, an essential nutrient for human life. High doses of radiation can be harmful, but low doses are safe, and probably beneficial, just like Aspirin.
There is a push now to record the dose of radiation every patient recieves as part of the permanent record of the exam. As I have mentioned in the page on Risks, Americans like to blame any and all misfortune on something and/or someone. 1 in 3 of us will get cancer. Radiation, like coffee, can be shown to be weakly carcinogenic if given in high enough doses to children. "Weakly" being an increase of 1 per 1,000 people, added on to the 333 who would get it anyway. It dosen't take much imagination to forsee that all 334 patients with cancer will want to blame something or someone for their disease. This is going to be a big field, and by recording everyone's doses (which implies there really is a significant risk) we are just fueling the fire.
Cancer is primarily a disease of aging. If you exclude major carcinogens, like smoking, the age adjusted cancer rate has not really changed in the last century. As we live longer, and eliminate frequent causes of death in the past, like polio, plague, strep throat and flu, more of us will die of cancer. If low level radiation is so terrible, why haven't we seen a dramatic rise in cancers after 1000 idiotic nuclear tests? Why do radiation workers live longer? In fact, we will probably see a reduction in cancer in this country over the next 20 years, because our addiction to carbohydrates like french fries, donuts, bread, potato chips and Coke is accelerating the rate of diabetes, obesity and heart disease so dramaticly that our life expectancy is bound to decrease, and with it the total number of cancers. But those who get cancer will still want to blame someone or something, and this trial shows radiation phobia is so prevalent, an intelligent jury could easily side with the victim. Radiologists are opening pandoras box by recording insignificant doses from CT scans on adults, as if they actually could be important.
Here is an abstract of the shipyard worker study
Bristish Journal of Radiology 100 year study
This year the society hosted a very interesting mock malpractise trial. It was very informative about the workings of such a trial for those who have never been through one. For me, it was scary, because I see what a Pandoras Box radiologists are creating as we feed our nation's radiation phobia.
The plaintif in the case was a young father, who's wife had died at age 33 with breast cancer. 10 years prior to the diagnosis of her breast cancer, the wife had several episodes of chest pain over an 18 month period. During that time she had 6 visits to the ER, and each time a CT was done to exclude pulmonary embolism( potentially lethal blood clots in the lungs.) The plaintif was suing the radiologist who read the exams, because he never once mentioned the potential for carcinogenisis which might be associated with low dose radiation. (They estimated the total dose around 200 mSv) He was not claiming the radiologist misread the CT scans, just a failure to warn about the risk, which he felt contributed to his wife's death from breast cancer.
The trial featured two expert witnesses for each side, a radiologist and a medical physicist. A real judge presided, and real lawyers argued for both sides. The jury was a group of volunteer laypeople, unfamiliar with the case. Interestingly, when the jury was away "deliberating", their discussion was broadcast to the audience.
I find the case alarming because it ended in a hung jury. 7 for the defense, 5 for the plaintif. This is disturbing for several reasons. First, these sounded like intelligent people, and yet 5 of them actually thought there was reasonable evidence that the CT scans contributed to the womans's breast cancer. Second, one of the key defense arguments was that 10 years ago, discussing potential radiation risks was not the standard of care, while today it is being debated that it should be.
The last five years has seen a surge in articles about the potential risks of radiation from CT scanning, written by both radiologists and non-radiologists medical professionals. All of these articles use the Linear no threshold theory (LNT, see my page "A radiobiology primer" for an explanation) to calculate highly inflated and alarming numbers about the risks of these scans. They tend to ignore the fact there are many places in the world with background radiation levels in excess of 150 mSv per year (our back ground level is 3 mSv, so this is the number the articles like to use as a baseline or "normal" level). In these areas every man, woman, child and fetus recieves a dose equivalent to 5 or 10 CT scans a year, with no ill effects. In fact, in some of these areas the average lifespan is longer than ours.
They also seldom mention that no one has ever shown a genetic or carcinogenic effect in adults from low level radiation. Quite the contrary. British radiologists were closely monitored for nearly 100 years in terms of their radiation dose, diseases and life span. In the early years of medical radiation, large doses were common. Since 1955, radiologists have received lower doses (still higher than non-radiologists) with no measurable ill effects. American shipyard workers building nuclear powered ships were closely monitored in a similar manner. The study was considered "negative" because they also lived longer and had less cancer than non-nuclear shipyard workers. It wasn't "negative". It showed the positive effects of radiation, an essential nutrient for human life. High doses of radiation can be harmful, but low doses are safe, and probably beneficial, just like Aspirin.
There is a push now to record the dose of radiation every patient recieves as part of the permanent record of the exam. As I have mentioned in the page on Risks, Americans like to blame any and all misfortune on something and/or someone. 1 in 3 of us will get cancer. Radiation, like coffee, can be shown to be weakly carcinogenic if given in high enough doses to children. "Weakly" being an increase of 1 per 1,000 people, added on to the 333 who would get it anyway. It dosen't take much imagination to forsee that all 334 patients with cancer will want to blame something or someone for their disease. This is going to be a big field, and by recording everyone's doses (which implies there really is a significant risk) we are just fueling the fire.
Cancer is primarily a disease of aging. If you exclude major carcinogens, like smoking, the age adjusted cancer rate has not really changed in the last century. As we live longer, and eliminate frequent causes of death in the past, like polio, plague, strep throat and flu, more of us will die of cancer. If low level radiation is so terrible, why haven't we seen a dramatic rise in cancers after 1000 idiotic nuclear tests? Why do radiation workers live longer? In fact, we will probably see a reduction in cancer in this country over the next 20 years, because our addiction to carbohydrates like french fries, donuts, bread, potato chips and Coke is accelerating the rate of diabetes, obesity and heart disease so dramaticly that our life expectancy is bound to decrease, and with it the total number of cancers. But those who get cancer will still want to blame someone or something, and this trial shows radiation phobia is so prevalent, an intelligent jury could easily side with the victim. Radiologists are opening pandoras box by recording insignificant doses from CT scans on adults, as if they actually could be important.
Here is an abstract of the shipyard worker study
Bristish Journal of Radiology 100 year study
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