Wednesday, June 13, 2012

mSv - how much radiation for you?

From many past posts - you may remember that the mSv is a millisievert - a measurement of radiation.  People can be exposed to radiation through a multitude of medical imaging procedures and the mSv is one way to track that exposure .

I won't go over the issue again - suffice it to say - there is a risk of cellular damage from the radiation and that can increase risk of cancer.  The machines themselves deliver different doses of radiation and are often not calibrated to make sure that the least radiation needed is what is being used.  The types of imaging (CT, Xray, MRA) transfer different doses as well.  I have previously posted charts on this. If you go to the Cancer Panel Report HERE, the chart is in chapter four.

Today an excellent study is published in JAMA and I think you can access the entire study, but definitely the summary paragraph (abstract) is enough to be helpful.

Briefly, this is what the researchers did and their overall findings.

They reviewed data from 5 different big health care systems.  For example, you may belong to an insurance program where everyone uses the same health care system (like Cone Health).  The researchers reviewed the records in 5 of these big programs and tracked the type and amount of imaging the patients received over the years (they signed release forms - don't panic).  The scientists estimated the dose of radiation through a detailed, multilevel process that is described in the article.  Certainly, there is room for error but the averages and trends are important. They categorized the radiation, in mSv, as an effective dose, a high dose and a very high dose.  The very high dose is >50mSv.   Their overall conclusion - covering the years 1996 to 2010 - and pertaining to the millions of people in those systems - is that all types of imaging increased and so did radiation.  As the CT scan is the target of most of my rants, I will tell you that in 1996, 52 of every 1000 patients had a CT scan which increased to 149 of every 1000 by 2010.  That is a 7.8% per year increase.  The researchers also conclude that each dose class, effective, high and very high was increased.  More people being scanned, and more people getting more radiation at all levels.  

If you go to this link and only read the section in the abstract under results - you will gain a lot of insight into this problem.  Of course, you can read as much as you like (I think).

Recall my recent post regarding the Consumer Reports collaboration with physicians groups which is meant to protect patients from overuse of this technology.  You can view that again here.

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