[gate-users] hot and cold sphere sources in warm background

[Schmidtlein, Ross/Sloan-Kettering Institute]

Hi Theo,

What activity per unit volume ratios are using between the background
and hot spots?  STIR allows AC correction via image_generate and
correct_projdata or sensitivity.  Also try running the simulation with
no hot spots and see what the reconstruction looks like then.

ross

-----Original Message-----
From: gate-users-bounces at lphe1pet1.epfl.ch
[mailto:gate-users-bounces at lphe1pet1.epfl.ch] On Behalf Of Mutanga
Theodore
Sent: Tuesday, February 08, 2005 6:58 PM
To: GATE feedback and helpline for Users
Subject: RE: [gate-users] hot and cold sphere sources in warm background


Thanks Ross for replying, I have not corrected for attenuation yet, but
I can't see any other activity distribution not even around the edeges,
just the four hot spheres. Are you suggesting that affter attenuation
correction the background will become visible ? I used very high
activities for the mother spheres. Also I haven't really found a
selfexplanatory method for attenuation correction of GATE output, there
are a lot of corrections that I cannot do just now, but I am still
reading about how to do them like arc correction and normalization. I
don't think those will prevent the background from being visible though.

Cheers

theodore

> Are you correcting for attenuation?  That effect will make most of you

> warm background activity appear on the edges.
>
> ross
>
> -----Original Message-----
> From: gate-users-bounces at lphe1pet1.epfl.ch
> [mailto:gate-users-bounces at lphe1pet1.epfl.ch] On Behalf Of Mutanga 
> Theodore
> Sent: Tuesday, February 08, 2005 6:18 PM
> To: gate-users at lphe1pet1.epfl.ch
> Subject: [gate-users] hot and cold sphere sources in warm background
>
>
> Greetings GATERS
>
> I have tried to design the phantom/source geometry where I have six 
> spheres in a warm background but I can't see the background source in 
> the reconstructed image.
>
> I used a cylinder as main phantom, with the six spheres as its 
> daughters. Then I created to sources and confined them to each of the 
> spheres and the background source I confined to the mother phantom 
> cylinder. When I reconstruc the images I only see the hot spheres. can

> someone tell me if there is something I overlooked ?
>
> Cheers
>
> Theodore
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