Re: radiation and CNS effects

["Gibbs, S Julian" <s.julian.gibbs@vanderbilt.edu>]

I apologize for omitting dose-response data from my 
previous posting on this subject.

Radiation-induced microcephaly and decreased IQ may occur 
from doses in the range of concern, i.e., 25-100 rem.  Some 
aspects of the dose-response curve suggest that this is a 
stochastic effect. Brain tumors may occur following doses 
of a few rem. These are definitely stochastic effects.  
Cataracts are clearly deterministic effects with known 
thresholds of about 1 Sv acute dose, higher with dose 
protraction.  Thre are case reports of patients who have 
received the full radiotherapy dose of 60 Gy in 6 weeks to 
the optic lens, with no cataract on long term followup.

***********************************************************
S. Julian Gibbs, DDS, PhD               Voice: 615-322-3190
Professor of Radiology                    FAX: 615-322-3764 
Dept. of Radiology & Radiological Sciences
Vanderbilt University Medical Center
Nashville TN 37232-2670        Email:j.gibbs@vanderbilt.edu
***********************************************************
Tell me and I forget; teach me and I remember; involve me
and I learn.
                       --Chinese proverb

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