[Gate-users] [ no subject ]

[Chen, Yu]

I see.

I downloaded your single_layer.mac and found the problem:

You set your module *readout* depth as 5!
while benchmarkPET is 1.

Remember in cylindricalPET system:

Level 1: rsector
Level 2: module
Level 3: submodule
Level 4: crystal
Level 5: layer

What the depth 5 means that you have electronics readout for each layer crystal!
If you have a penetration or scatter in different crystals for one incident photon,
you will get multiple pulses there for multiple singles for the same photon.
That's why you get many intercrystal coincidences.

Now problem is:

1) are you sure you used the same macro for both GATE version (setDepth 5)?
If yes, that means for some reason that readout (setDepth) module does not work well in old
GATE.

2) did MJ use the exact same single_layer.mac (setDepth 5)?

No matter what, setDepth 5 is wrong unless you really want to simulate penetration effect.

Please change it to setDepth 1 (or 2 if you have a PMT for each module) and see what you get. 


Yu Chen, Ph.D.
University of Massachusetts Medical School
Division of Nuclear Medicine
55 Lake Avenue North
Worcester, MA 01655-0243
Phone:  (508) 856-6123
Fax:    (508) 856-4572



-----Original Message-----
From: i.torres at lrz.tu-muenchen.de [mailto:i.torres at lrz.tu-muenchen.de]
Sent: Wed 12/19/2007 2:06 PM
To: Chen, Yu
Subject: RE: RE: [Gate-users] [ no subject ]
 
Hi Yu Chen,

> Do you have the energy plot from single_layer?

I do not have it here. But I send you the results from another GATE user
that has the same problems. I posted the emails from this GATE user (he
could not do it), but I am waiting for the administrator approval. You
will see his emails soon. But in advanced I send you the plots of the
enery spectra.

> I tend to agree with MJ now that problem may not from GATE.

I do not know where is the problem, but we have the recommended versions
for CLHEP, Geant, gcc..., the benchmark is fine, but the results from the
ECAT and single_layer macros are not right... puzzling.

Thank you for you time and help.

Bye,

Irene and Jasmine

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