[gate-users] sample image from my IQ_phantom simulation

[Schmidtlein, Ross/Sloan-Kettering Institute]

Hi Theodore, 

I agree that the air in the source volume would creat images just like
the one's that that you have shown (e+ range in air is ~100 cm).  I
don't see the purpose of the "Holder for background source" volume I
would remove it.  Also, it is my impression the nested volumes are more
efficient in Geant4 (does anyone know if am I correct about this?, Seb?)
so you might want to change that too, but I don't think that it is a big
deal in any case.  

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: Friday, September 16, 2005 5:06 AM
To: GATE feedback and helpline for Users
Subject: RE: [gate-users] sample image from my IQ_phantom simulation

Hi ross
I attach a copy of my phantom macro and some images . I may have found
something that could have been the cause of the background disappearing.
I had defined an inner cylinder of air surrounding the sources ( this I
called background source holder and it is where I placed the warm
background source) I am thinking that this should have been water and
not air ? since most of the positrons will escape right thru ?


> Hi Theodore,
>
> Attenuation correction can be done via STIR by building an attenuation

> coefficient image and then using the projection data correction 
> routine to scale the data properly.  That's probably the most straight

> forward method.  Also, arc correction is important in order to avoid 
> object distortions for this phantom.
>
> I have been doing a similar reconstruction with the DLS and have been 
> unsure about the counting statistics with respect to the contrast 
> ratios.  How many coincidences do you have in your image data?
>
> Cheers,
>
> 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: Thursday, September 15, 2005 7:20 AM
> To: gate-users at lphe1pet1.epfl.ch
> Subject: [gate-users] sample image from my IQ_phantom simulation
>
> I will like to present an image that I obtained using a simulation of 
> the Discovery St and reconstruction with stir for the iq-phantom, some

> spheres are missing and there is heavy attenuation , I am currently 
> exploring ways of simulating and correcting for attenuation with GATe 
> and STIR, any suggestions?
>
>
>
>
>
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