RE: Irradiation of mouse thymus

[Karin Gordon <KGordon@exchange.hsc.mb.ca>]

The HVL in PB for Cs-137 is 0.5 cm, so you're right, lead foil definitely
wouldn't be appropriate.  First find a  thick-walled cylindrical lead pot,
and get your machine -shop to cut it in half in a sagittal plane (top to
bottom).  Then they should tool a key-hole cut-out in  the side of the
shield approximately the size and shape of the thymus gland.    We regularly
receive our I-131 treatment dose material in lead pots about 2 cm thick,
which would cut the incident dose outside the treatment area to about 0.44
Gy. Obviously, you can cut that dose even lower by using a greater
thickness of Pb. The thymus approximate shape and position should be
outlined with a felt tip pen on the exterior chest wall of the mouse.   Then
the mouse can be positioned within the modified lead pot with the chest wall
markings matched to the cutout in the lead.  I'd probably use some surgical
cotton padding and lots of tape to properly secure the mouse in position.  

How much shielding and immobilization gear you can use around your mouse
obviously depends on the configuration and size of the irradiation chamber
in your machine.

Good luck!!.

Karin



	 ----------
> From: 	Larson, Ron[SMTP:RLARSON@RESEARCH.USF.EDU]
> Sent: 	Wednesday, December 01, 1999 3:35 PM
> To: 	Multiple recipients of list
> Subject: 	Irradiation of mouse thymus
> 
> We have a researcher here at the university that would like to
> specifically irradiate the thymus of a mouse using the Cesium-137
> irradiator. He asked our office how he could go about doing this. The
> use of the collimator will not be possible (at least I don't think so)
> and he wants to wrap the anesthetized mouse with lead foil and have a
> small opening exposing the area of the thymus. My initial response was
> that the lead foil would not adequately shield the rest of the mouse. He
> wants to irradiate with a dose of 7 Gray which would be about 10 minutes
> of exposure time.  If anyone has any experience or suggestions that our
> office could pass onto this researcher, we would be most appreciative.
> Please respond to the e-mail address below. Thanks!
> 
> Ron Larson
> USF Asst. Radiation Control Officer
> 3500 E. Fletcher Avenue
> Suite 523
> Tampa, FL  33613
> Office: 813-974-7656
> Fax: 813-974-5938
> E-Mail: rlarson@research.usf.edu
> 
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