[ RadSafe ] Chris Busby

[Busby Chris]

Dear Otto,

1. Its is a comparison of two probabilities. "Very small" is not a quantitative measure. You have to compare the probability of a Y90 decay in 12 hours with the probability of the same cell getting 2 hits in 12 hours from the same dose of external radiation. However small the absolute probability for one atom sequence the number of atoms involved is very large (as the overall contamination goes up)  and so the product gives you the probability of a second event in the body/tissue. The probability of a second event from external is vanishingly small though calculable. There are 10^13 cells. The probability of two tracks from external is 1 in E-26. The probability from two tracks from Sr90 Y90 is a lot less (12 hr period and 64hr decay so the enhancement is about E+22 for a simngle atom, decay internal vs external.

2. Not if they are bound to the DNA in condensed form. Furthermore, there is the ionisation change at the decay locus from transmutation. Sr++ to Y+++ is an ionisation. Then Y+++ to Zr is also an ionisation from transmutation redox. And even if it is very small (you can work it out on complete randomness into 4pi) it is not as small as E-26 and there are a lot of atoms.

3. But why doesnt someone do the experiment?? 

C  

-----Original Message-----
From: radsafe-bounces at agni.phys.iit.edu on behalf of Otto G. Raabe
Sent: Fri 22/04/2011 03:45
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] Chris Busby
 
At 12:28 PM 4/21/2011, Billwrote:
>My apologies-I was looking at the 90Sr half-life not the 90Y half life. The
>average time between decay events is 3.9 days. This is still a relatively
>long time.
***********************
That makes little difference.

The chance that the two beta particles, which would be expected have 
widely different energies and ranges, will both go in the same 
direction and hit the same target DNA is very, very  small anyway.

Otto


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Prof. Otto G. Raabe, Ph.D., CHP
Center for Health & the Environment
University of California
One Shields Avenue
Davis, CA 95616
E-Mail: ograabe at ucdavis.edu
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