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

[Sebastien JAN]

Hi Christian,

Of course, you can do that if you want to blur the Z coordinate.
Actually, this coordinate is the depth of interaction in the crystal and 
it is not measured in pet or spect systems. This is why Pznew is equal 
to Pz in the basic code.

Cheers
Seb

Christian Wietholt a écrit:
>>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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