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Re: Nuclear medicine rooms shielding

Dear Hassan
Shielding calculations for nuclear medicine are very special 
because they require a complete knowledge of all the operations 
with radioactive materials in the installation.
First of all you have to determine the workload of your 
installation, W, in mCi.hr/wk. This is done by taking the no. 
of examinations per isotope and the avg time required for it. 
As an example 300 examinations/wk with Technetium-99 for bone will 
give tipically 1500 mCi.hr/wk.
The equation used for calculations is:

k=P.d.d/WT.gamma  

where: P is the permissible dose in the point of calacul.
       d is the distance from the camera to the point of calcul
       T is the occupation factor
       gamma is the exposure rate constant
 The TVL for Tc-99m are: .083 cm (Pb), 6.6 cm(Concrete
The no of TVL's is given by: log(1/k)

As for the hot room I used a 3 mm Pb thickness of the external 
walls and a separation wall with 5mm Pb between the storage and 
preparation area, depending of course on the workload and 
geometry of the installation.

The only reference I found is the excellent paper of 
J.p.Bhatnagar,"Structural shielding Considerations in the 
design of a Nuclear Medicine Department", presented at 26th 
Annual meeting of the HPS, 1981,Louisville, Kentucky,USA

Good luck!

Sergio Faermann,Ph.D.
Inst. of Oncology
Soroka Medical center
POBOX 151
84101 Beer-Sheba
Israel


On Wed, 26 Aug 1998, Ghamdi, Hassan A wrote:

> I have here some questions regarding the shielding of hot lab in nuclear medicine, I need your help in this regard
> How much the lead shielding thickness required for the regular nuclear medicine hot lab  ? Butting extra safety margin, can we used 6 mm Pb thickness or it can create another problem, In my knowledge a thickness of 3-4 mm of lead will be enough? Are there a way to calculate the required shielding exactly, what are the reference ? 
> 
> With my thanks in anticipation for any  reply
> 
> Hassan
> E-mail ghamha0q@aramco.com.sa
> fax 99638778841
> tel 96638773168   
> 
> 
> 
> 
> 
> AOC
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