[gate-users] Phantom problem

[Sophie Kerhoas]

Hi Mikhail and Ross,
   I think I already see macro where phantom are daughter of the system
instead of world...so I don't think it is the problem.

I would like to know how did you do to be sure that the e+ reach the
crystals?
I am not familiar with the ASCII output, it's why I ask you this
question. Did you look in which Volume ID the annihilation happens ?
with the root output, I would try
Hits.Draw("volumeID","processName==\"annihil\"")

Sophie

On Tue, 2005-05-24 at 23:50, Schmidtlein, Ross/Sloan-Kettering Institute
wrote:
> Hi Mikhail,
> 
> In your definition of the phantom it looks like you made it a daughter
> of the ECAT system and not the world.  That would account for it not
> having any effect in the simulation.
> 
> ross
> 
> -----Original Message-----
> From: gate-users-bounces at lphe1pet1.epfl.ch
> [mailto:gate-users-bounces at lphe1pet1.epfl.ch] On Behalf Of Mikhail
> Shilov
> Sent: Tuesday, May 24, 2005 2:30 PM
> To: gate-users at lphe1pet1.epfl.ch
> Subject: [gate-users] Phantom problem
> 
> 
> Thanks everyone who responded to my inquiry about energy spectrum of the
> detected gamma photons. After careful examination of my gateHits.dat
> output file I finally figured out the reason for my confusion and why I
> was getting so much noise in the output sinograms. 
> 
> In my test simulation I used a single ring camera which consists of
> 6X112 BGO crystals grouped in 112 blocks. I use a e+ point source in the
> center surrounded by a 10 mm thick water phantom. Since the mean free
> path of a positron in water is about 1mm, I assumed that the all
> annihilations should happened in the phantom near the source. 
> 
> Never the less, when I analyzed my gateHits.dat output of the run I
> found out that almost all the annihilations happened in the BGO crystals
> ( I did attached the phantom to SD with /gate/myphantom/attachPhantomSD
> ). It looked like the phantom didn't even exist in the simulation.
> 
> Here is macro for my phantom. I don't see anything wrong with it:
> 
> /gate/ecat/daughters/name myphantom
> /gate/ecat/daughters/insert cylinder /gate/myphantom/geometry/setRmax
> 10.0 mm /gate/myphantom/geometry/setHeight 20.0 mm
> /gate/myphantom/placement/setTranslation 0.0 0.0 0.0 cm
> /gate/myphantom/setMaterial Water /gate/myphantom/vis/forceSolid
> /gate/myphantom/vis/forceWireframe
> /gate/myphantom/vis/setColor green
> 
> /gate/myphantom/attachPhantomSD
> 
> a point source is in the origin ( 0. 0. 0. )
> 
> If anyone have any suggestions for my problem it would greatly
> appreciated.
> 
> Mikhail A. Shilov
> The Johns Hopkins University
> Department of Radiology
> Tel:  443-287-7315
> Fax:  410-614-1977
> mailto: mshilov1 at jhmi.edu
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> 
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