[gate-users] Re: gate-users Digest, Vol 17, Issue 15

[Christian Wietholt]

> Message: 3
> Date: Wed, 10 Aug 2005 16:20:43 +0000
> From: Christian Wietholt <cwietholt at nhri.org.tw>
> Subject: [gate-users] spblurring folow-up
> To: gate-users at lphe1pet1.epfl.ch
> Message-ID: <200508101620.43733.cwietholt at nhri.org.tw>
> Content-Type: text/plain; charset=iso-8859-1
>

Dear all, 

Yesterday I posted below message about my troubles with the spblurring 
functionality in Gate. After getting really desperate I decided this morning 
to take a look at the source code. I made the following changes to 
GateSpblurring.cc

I changed line 77 from :

 G4double PzNew = Pz;

to 

 G4double PzNew = G4RandGauss::shoot(Pz,m_spresolution/2.35);

After some testing, it seems to have resolved the problems I mentioned below. 
I was hoping for some comments, just to verify if I am doing anything wrong 
with this change. 

I would appreciate your input. 

Best Regards, 

Christian

> Dear all,
>
> I know I have been posting a lot about the spblurring functionality in
> Gate, and I apologize for any unnecessary posts. As I mentioned in a
> previous post, the blurring does not have any effect on the globalPosZ
> variable in gateSingles.dat file. But, when I want to create an image from
> the ASCII output for a 0 degree projection, don't I use globalPosZ as the
> value for the ordinate, and the globalPosY as the value for the abscissa in
> the projection image. Please correct me if I am wrong. If spblurring does
> not have any effect on globalPosZ, how can I create a representative
> projection image?
>
> In my simulation I simulated a pointsource projecting through a 5mm pinhole
> which should result in a projected disc of 10mm radius. I did spblurring of
> 0mm and 30mm (30mm is just for demonstrating the effect).
> Below please find the distribution values of globalPosX, Y, and Z in
> gateSingles.dat. Btw. I get similar results in Gate 1 & 2.
>
> for a 0 degree simulation: Here I think x is just the depth of the Single
> in the detector and does not play a role in the image formation, but Y and
> Z should be the image coordinates.
>
> spblurring 0mm:
> 	average	var		stdev
> X	242.491	3.228	1.797
> Y	0.528	70.873	8.419
> Z	0.140	91.875	9.585
>
> spblurring 30mm:
> 	average	var		stdev
> X	241.315	176.202	13.274
> Y	1.332	258.672	16.083
> Z	0.140	91.875	9.585
>
> (for Z I think the stdev should be similar to the stdev of Y)
>
> I would appreciate any comments or corrections to this line of thoughts.
> I am looking forward to hearing from you.
>
> Best Regards,
>
> Christian
>
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