[ RadSafe ] Beta emitters and external risks

[John Jacobus]

Dale,
Yes, I stand corrected.  I thought you were refering
to a contact dose.  From the "Radionuclide and
Radiation Protection Data Handbook," the positron dose
at 10 cm is 0.096 mSv/hr/MBq/cm^2 while the photon
dose rate to the skin is 0.0068 and 0.0064 for the
deep dose.  For  O-15, the positron dose rate is 0.14
mSv/hr/MBq/cm^2, which is the same for P-32.  Very
interesting.

What cutoff dose rate would you use for beta exposure
concerns?  I was thinking of 800 keV.

--- Dale Boyce <daleboyce at charter.net> wrote:

> Hi John,
> 
> I think you misunderstood me. Unshielded, you get a
> higher dose rate from 
> the positron than the annihilation radiation with
> F18. People can and have 
> been hurt by this. Yes it is a shallow dose, but
> skin erythema can be pretty 
> nasty.
> 
> Dale
> ----- Original Message ----- 
> From: "John Jacobus" <crispy_bird at yahoo.com>
> To: <daleboyce at charter.net>; <radsafe at radlab.nl>
> Sent: Saturday, October 15, 2005 7:58 PM
> Subject: Re: [ RadSafe ] Beta emitters and external
> risks
> 
> 
> > Dale,
> > You misunderstood what I am look for. If you had a
> > drop of a beta emitting radionuclide on a table
> what
> > betas are of concern if you are standing by the
> table?
> > by the way, F-18 and other PET radionuclides emitt
> > positron or beta+ particles. Shielding for the
> > annihilation photon radiation shields for the
> positron
> > particles.
> >
> > --- radsafe-bounces at radlab.nl
> <daleboyce at charter.net>
> > wrote:
> >> Hi John,
> >>
> >> I wouldn't ignore skin dose as a radiation
> hazard.
> > At around 9
> >> rad/hr/microcurie/cm^2 high energy beta emitters
> are
> > probably the biggest
> >> radiation hazard normally encountered in a
> research
> > environment.
> >>
> >> There are other beta emitters that present a
> hazard,
> > and some come
> >> disguised. F-18 is known for its use in PETT with
> > the 511 annihilation
> >> radiation, but the intermediate energy positrons
> can
> > give one heck of a beta
> >> burn (and have in the past) before the gamma dose
> is
> > significant.
> >>
> >> While low energy beta emitters such as C-14 may
> > present a reduced risk due
> >> to air and dead layer absorption, one shouldn't
> > ignore the potential rish
> >> from beta emitters.
> >>
> >> ----- Original Message ----- 
> >> From: "John Jacobus" <crispy_bird at yahoo.com>
> >> To: "radsafe" <radsafe at radlab.nl>
> >> Sent: Friday, October 14, 2005 4:42 PM
> >> Subject: [ RadSafe ] Beta emitters and external
> > risks
> >>
> >>
> >> > Question:  Would you say that beta emitters
> pose
> > an
> >> > external radiation hazard or risk?  I am not
> > consider
> >> > skin contamination.
> >> >
> >> > Are there any (other) beta emitters that you
> would
> >> > consider to be a significant external hazard?
> >> >
> >> > What is your criteria for this judgement?
> >> >
> >> > (Background:  I would in a medical research
> > facility,
> >> > and we require beta shields for work involving
> > large,
> >> > e.g., 10 mCi/370 MBq, amounts of P-32.  Are
> there
> >> > other beta emitters we should worry about?)
> >> >
> >> > +++++++++++++++++++
> >> > On Oct. 5, 1947, in the first televised White
> > House address, President
> >> > Truman asked Americans to refrain from eating
> meat
> > on Tuesdays and poultry
> >> > on Thursdays to help stockpile grain for
> starving
> > people in Europe.
> >> >
> >> > -- John
> >> > John Jacobus, MS
> >> > Certified Health Physicist
> >> > e-mail:  crispy_bird at yahoo.com
> >> >
> >> >
> >> >
> >> >
> >> > __________________________________
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> >
> > +++++++++++++++++++
> > On Oct. 5, 1947, in the first televised White
> House address, President 
> > Truman asked Americans to refrain from eating meat
> on Tuesdays and poultry 
> > on Thursdays to help stockpile grain for starving
> people in Europe.
> >
> > -- John
> > John Jacobus, MS
> > Certified Health Physicist
> > e-mail:  crispy_bird at yahoo.com
> >
> >
> >
> > __________________________________
> > Yahoo! Music Unlimited
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> 


+++++++++++++++++++
On Oct. 5, 1947, in the first televised White House address, President Truman asked Americans to refrain from eating meat on Tuesdays and poultry on Thursdays to help stockpile grain for starving people in Europe. 

-- John
John Jacobus, MS
Certified Health Physicist
e-mail:  crispy_bird at yahoo.com


		
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