[ RadSafe ] Biological dose measures promise new view of cardiac imaging risk

[Bjorn Cedervall]

The bottomline of these DSB measurements are definitely worth

some extra thoughts. I have made a couple of calculations (two

different strategies) and in both cases I come down to the order

of 10E9 lethal DSBs (in the clonogenic sense but not necessarily

functional, using a value of about 30 DSBs/cell,Gy) if we consider

the mass of the heart as the target.

 

Please comment and correct me if I am wrong,

 

Bjorn Cedervall    bcradsafers at hotmail.com

 ---------------------------------------
 
> To: radsafe at radlab.nl
> From: cjb01 at health.state.ny.us
> Date: Thu, 30 Apr 2009 10:55:50 -0400
> Subject: [ RadSafe ] Biological dose measures promise new view of cardiac imaging risk
> 
> 
> Below is the url for a fascinating article on AuntMinnie:
> 
> <http://www.auntminnie.com/index.asp?Sec=sup&Sub=car&Pag=dis&ItemId=85566&wf=3066>
> 
> 
> It references presentations at the 2009 European Congress of Radiology, by
> investigators from the Institute of Radiology, University of
> Erlangen-Nürnberg, in Erlangen, Germany, and Saarland University in
> Saarbrücken, Germany, who measured the direct in vivo effects of ionizing
> radiation on blood DNA in cardiac CT and angiography exams. They compare
> the measurements to traditional dose-length-product and dose-area-product
> measurements of radiation dose. Their technique involves counting double
> strand breaks in lymphocytes before and after irradiation.
> 
> Is anyone familiar with the original studies upon which this article is
> based?
> 
> 
> Some excerpts from the article and some questions/comments from me:
> 
> 1) "Among all the biological effects of ionizing radiation in the body,
> DSBs are among the most significant effects."
> 
> >>>>>What is the basis for this statement? Are we assuming DSBs cause
> cancer? If so, how do asbestos fibers, benzene and human papilloma virus
> cause DSBs?
> 
> 2)"The exposure of mammalian cells to ionizing radiation causes DSBs within
> minutes."
> 
> >>>>>Why does it take so long, I would think the breaks would be
> instantaneous once the secondary electron breaks chemical bonds on both
> rails of the helix?

> 
> 3) "...during a normal working day, we could not find signs of biological
> effects in cardiologists."
> 
> >>>>>This suggests a low dose/low dose-rate threshold for biological
> damage. Is LNT now defunct, or can someone save it?


> Clayton Bradt
> dutchbradt at hughes.net


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