CT and cancer risk in children - so much more to consider...
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CT and cancer risk in children - so much more to consider...
Chat about radiology with radiologists and those who want to get into the speciality
A fresh Lancet article has outlined a tripled risk of leukaemia and brain cancer in children exposed to over 50 mGy of radiation through CT examination ( link here ). Understandably, this generates me
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Forums » Open clinical » Radiology » CT and cancer risk in children - so much more to consider...
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CT and cancer risk in children - so much more to consider...
posted at 7/6/2012 1:54 PM BST
on bmj.com
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Posts: 326
First: 27/10/2011 Last: 14/6/2013 |
A fresh Lancet article has outlined a tripled risk of leukaemia and brain cancer in children exposed to over 50 mGy of radiation through CT examination (link here). Understandably, this generates media interest, with a reasonably well balanced article by the Guardian highlighting the need to judge exposure according to whether the benefits outweight the risks. Several important points arise from this news: 1) Just how can we really judge benefit vs risk in such situations on a case-by-case basis (as we the DoH claims we must in the Gaurdian article)? Humans are notoriously bad at doing this, often relying on crude heuristics. 2) The study was conducted between 1985 and 2002, since when there have been significant improvements in dose reduction and a tightening of the belts when it comes to scanning in children. This underlines the signficant issue of just how can be we best understand the impact of what we do in the present? 3) What about adults? We scan so frequently in some groups of individuals, often with the feeling from the radiology perspective that the imaging is just to reassure the clinicians rather than diagnose or guide therapy. How is the patient doing? Is the scan actually necessary? As many as 30% of adult CTs have been judged to be unnecessary (BMJ article link) Thoughts, wisdom and debate all welcomed. Please also post links to salient papers on the topic of cancer risk and iatrogenic radiation... |
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Re: CT and cancer risk in children - so much more to consider...
posted at 22/5/2013 10:55 PM BST
on bmj.com
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Posts: 326
First: 27/10/2011 Last: 14/6/2013 |
The case for further diligence in the application of CT in the paediatric population grows... A recent article published in the BMJ has shown a 24% increased incidence in cancer with a previous CT scan greater than one year prior. The relationship was also dose-responsive, but did tail off with time... Does this clear up the debate? Not yet. Doses have dropped since the data retrieval window of 1985-2005 and we already know that rapidly growing/dividing tissue is far more sensitive to ionising radiation. But this is a large study (680,000 exposed to CT) and hopes are raised for achieving similar such numbers in an adult population study, where the home truths are far harder to pin down. I still have the nagging feeling that there is a pro-CT lobby somewhere that doesn't want to find out the results...
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Re: CT and cancer risk in children - so much more to consider...
posted at 23/5/2013 10:22 PM BST
on bmj.com
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Posts: 2133
First: 12/3/2010 Last: 16/6/2013 |
I seem to remember, HR, that there used to be a debate on whether there was a critical dose of radiation, below which there was no significant risk, and above which risk became dose related. Does this still exist, or is any radiation considered potantially harmful? John |
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Re: CT and cancer risk in children - so much more to consider...
posted at 24/5/2013 9:39 AM BST
on bmj.com
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Posts: 326
First: 27/10/2011 Last: 14/6/2013 |
That is the difference between the deterministic and stochastic effects of radiation... Deterministic effects are dose related, sometimes with a threshold above which symptomatic effects are noted. These can be hairloss, skin damage and enteritis, the kind of acute radiation sickness that you might see in the movies. Stochastic implies a certain randomness to the effect of radiation: a little DNA damage here, a little mutagenesis there, which could lead to cancer induction, germ line changes, and such like. This is harder to 'determine' of course, not least because of DNA repair mechanisms, and so makes pinning down the risk much harder. We do know that such stochastic effects are more likely if the underlying tissue is dividing rapidly, hence the dangers of radiation in childhood and adolescence, and the efficacy of radiotherapy. Some cancers can clearly still be (or appear to be) deterministic... just imagine a ionising sledgehammer to crack a DNA-nut. Much of our perceived knowledge of radiation effects has come historically from the fall out from the desperate events in Japan at the end of the Second World War. Studies were metered out to look at the outcomes with those exposed to levels of radiation according to dose, often estimated from distance to the epicentre at the time of exposure and how much hanging around was done after. Quite surprisingly, apart from those who passed early after the event from acute (probable deterministic) effects, many of the cohort went on to out-live their contemporaries, leading to the still questionable idea of hormesis - that some radiation may be good for you. This could also be a poor control bias effect, but if you think about hormesis in another way, it doesn't seem so outlandish. Last week's In Our Time on Radio 4 was on Cosmic Rays, the high energy speedy interstellar/galactic subatomic particles that bombard our planet and ourselves. The expert panel revealed that 100's of such particles pass through us each second - we are bathed in ionising radiation and have been through all our history. It is a part of who we are and how we have survived as humans and living organisms. To deny that evolution has ignored the ability of life to evolve through such effects would be brave. Have a think on that the next time you hop on a plane! |
Forums » Open clinical » Radiology » CT and cancer risk in children - so much more to consider...
