[Gate-users] septa setting

Tue Nov 27 05:05:05 CET 2007

Hi gate-users
I tried to set septa in my simulation system with following scripts:
#       SEPTA
/gate/head/daughters/name septa
/gate/head/daughters/insert box
/gate/septa/placement/setTranslation -1.5 0.0 0.0 cm
/gate/septa/geometry/setXLength 5.0 cm
/gate/septa/geometry/setYLength 32.0 cm
/gate/septa/geometry/setZLength .5 mm
/gate/septa/setMaterial Tungsten
/gate/septa/repeaters/insert cubicArray
/gate/septa/cubicArray/setRepeatNumberX 1
/gate/septa/cubicArray/setRepeatNumberY 1
/gate/septa/cubicArray/setRepeatNumberZ 3
/gate/septa/cubicArray/setRepeatVector 0.0 0.0 10.0 cm
/gate/septa/vis/setColor blue
/gate/septa/attachPhantomSD
I tried to analysis the total counts with benchmark.C. But I find that there
is no difference within or without setting septa. 
Any suggestion will be appreciated.

Guocheng Wu
Software Department
Neusoft Positron Medical Systems Co.,Ltd.

No.2 Xin Xiu Street, Hun Nan New District, Shenyang 110179, PRC

Tel: +86 24 836 61980
Fax: +86 24 836 61796
Mobile: +86 13604039065
Email: wuguocheng at neusoft.com
Website: http://medical.neusoft.com 

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发送时间: 2007年11月26日 13:31
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主题: Gate-users Digest, Vol 18, Issue 20

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Today's Topics:

   1. RE : [Gate-users] positron range (Samuel BURG)
   2. RE: positron range (JinSu Kim)

----------------------------------------------------------------------

Message: 1
Date: Sun, 25 Nov 2007 16:22:47 +0100 (CET)
From: Samuel BURG <samuel_burg at yahoo.fr>
Subject: RE : [Gate-users] positron range
To: JinSu Kim <patentjs at snu.ac.kr>,	Users Gate
	<gate-users at lists.healthgrid.org>
Message-ID: <827344.90782.qm at web23211.mail.ird.yahoo.com>
Content-Type: text/plain; charset="iso-8859-1"

Well, 

I'm not a ''king'' in positron range questions, but isn't 0.2 mm about the
MEDIUM range and 0.43 mm about the MAX range in water for the 18-F positron
?

Best regards,

Samuel Burg

JinSu Kim <patentjs at snu.ac.kr> a icrit :                        Dear Gate
users

  1st question is ..
  During gate simulation, I found following error message
  Is it negligible?
  [GateTrajectoryNavigator::FindAnnihilationGammasTrackID]  WARNING :
positron found and photonID vector size: 1

  2nd question is about the Positron range of F-18
  In the literature, positron range of F-18 was 0.2 mm at water
  However, I found that the positron range of F-18 was 0.43 mm at water in
GATE simulation.
  What is the difference of that?

  Best regards

  _______________________________________________
Gate-users mailing list
Gate-users at lists.healthgrid.org
http://lists.healthgrid.org/mailman/listinfo/gate-users

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Message: 2
Date: Mon, 26 Nov 2007 14:26:10 +0900
From: "JinSu Kim" <patentjs at snu.ac.kr>
Subject: RE: [Gate-users] positron range
To: <knicolas at mail.ntua.gr>, <gate-users at lists.healthgrid.org>
Message-ID: <000001c82fec$db1409d0$3f8311ac at LocalHost>
Content-Type: text/plain; charset="us-ascii"

Dear Nicolas and Gate users

Regarding Positron range

I have used Fluorine-18 source for simulation (ion 9 18 0 0)

Phantom

Geometry ~ diameter: 6 cm & Length: 15 cm

Material ~ water

Source 

Shape and dimension of fluorine-18 ~ 1) point source & 2) length 15 cm and
diameter 0.1 cm

I have addressed that the positron range of F-18 was 0.43 mm in my
simulation result

That is mean value. Maximum value of positron range was near 2 mm.

As I have mentioned the reference value of positron range of F-18 was 0.2 mm
(mean value)

Another question is regarding warning message.

Following warning message
"[GateTrajectoryNavigator::FindAnnihilationGammasTrackID]  WARNING :
positron found and photonID vector size: 1 " 

were occurred in different simulation study

That occurred in many times

However, the result of simulation was reasonable compared with the measured
value.

Best regards

JinSu Kim

  _____  

From: Nicolas Karakatsanis [mailto:knicolas at mail.ntua.gr] 
Sent: Friday, November 23, 2007 9:22 PM
To: JinSu Kim; gate-users at lists.healthgrid.org
Subject: Re: [Gate-users] positron range

Dear JinSu

regarding your first question this is a warning message generated by GATE in
the following cases
a) a positron was generated but no annihilation gamma photons were produced.
If your geometry around your source was not dense enough to ensure
annihilation of some emitted positrons then it is very likely that this
warning message will appear during GATE simulation. This warning is repeated
every time a trajectory with this properties is processed by GATE trajectory
navigator.

b) a positron was generated and then either 1 or more than 2 annihilation
gammas were produced. In most cases you would expect to have two
annihilation gammas. So this is unlikely to happen.
In your case one gamma photon was generated after the positron. This is
strange for GATE trajectory navigator and we might need to investigate it
further.
Please can you give us more details on this. For example, was this warning
message produced many times? What kind of source have you used? What was the
geometry of your phantoms?
If you repeat the simulation with a thicker surrounding attenuation volume,
will you still get these warnings?

As far as the second question is concerned the GATE developers community has
been investigating the methods used by GATE to calculate positron range
recently because we observed some strange results regarding the positron
annihilation distance. It is likely to have discrepancies between literature
and GATE.
However we would like you to tell us how did you estimate the positron range
you mention. 
Is this question related to the same simulation that generated the previous
warning message?If not, then what kind of source have you used and what was
it's shape and dimensions.
Moreover it will be helpful if you can tell us a little more about the
properties (shape, dimensions) of the water volume that surrounded your
source.

Nicolas

Nicolas Karakatsanis
PhD Candidate
School of Electrical and Computer Engineer
National Technical University of Athens

JinSu Kim wrote: 

Dear Gate users

1st question is ..

During gate simulation, I found following error message

Is it negligible?

[GateTrajectoryNavigator::FindAnnihilationGammasTrackID]  WARNING : positron
found and photonID vector size: 1

2nd question is about the Positron range of F-18

In the literature, positron range of F-18 was 0.2 mm at water

However, I found that the positron range of F-18 was 0.43 mm at water in
GATE simulation.

What is the difference of that?

Best regards

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