[Gate-users] Three problems with Gate 6.1

[MinJae Park]

Dear Nikolaos,

I use two sphere of water phantom as your post.
1. radius : 0~0.01mm
2. radius : 0.011mm~20cm
Source is in the sphere #1.

However, I couldn't choose physical model for low energy at this
moment because of "COMMAND NOT FOUND".

Therefore, the result, which I got, could be wrong.

I will post the result after using physical model for low energy.

Thank you,
MJ

//=================================================
//  MinJae Park, Ph.D.
//
//  Johns Hopkins University
//  School of Medicine, Dept of Radiology
//  Division of Medical Imaging Physics
//
//  DialTo:+1-443-287-2005 (Office)
//  MailTo:MJ at ToTi.us, MJ at JHMI.edu
//
//  "You see, But you do not Observe"  - Sherlock Holmes -
//=================================================



On Wed, Jul 6, 2011 at 6:37 PM, Nikolaos A. Karakatsanis
<nkaraka2 at jhmi.edu> wrote:
> Dear Min-Jae,
>
> thank you for reporting this potential problem in GATE.
>
> I personally had come up with this suspicious behavior in the past too.
> After conducting a validation study using different materials and sizes for
> the source and the attenuating medium, I concluded that the problem is
> related with the set-up of source-medium employed to access positron range.
>
> The distance corresponding to the local minimum observed between the two
> peaks of the positron range is strongly related with the distance of the
> outer boundary of the source from the center of the source. In other words,
> the local minimum is observed almost exactly at the interface between the
> source and the surrounding attenuating material.
>
> I would suggest you not to use different materials for the source and the
> attenuating volume. You can use water for both volumes, which is a very
> realistic set-up to access positron range.
>
> However, even if the problem is eliminated, the behavior you report is
> suspicious and probably we need to go through the implementation of the
> physical processes in GATE and Geant4.
>
> To assist us, please attach the positron range spectrum after using GATE 6.1
> and GATE 5 and kindly provide us with a description of the materials and the
> geometry of source and attenuating medium that you have been using
>
> thank you.
> Nicolas
>
> ____________________________________________________
> Nikolaos A. Karakatsanis, PhD
> Division of Nuclear Medicine
> Department of Radiology
> Johns Hopkins Medical Institutions
> Room 3263, JHOC Bldg
> 601 N. Caroline Street
> Baltimore, MD, USA, 21287
>
>
> On 7/6/11 5:52 PM, MinJae Park wrote:
>>
>> Dear Gaters,
>>
>> Recently, I installed Gate 6.1 to investigate the positron range of Rb-82.
>>
>> But, I can't use different physical model using "setModel" command.
>> I got an error as below when I tried to use setModel.
>> [G4-cerr] ***** COMMAND NOT FOUND
>> </gate/physics/processes/ElectronIonisation/setModel PenelopeModel e+>
>> *****
>>
>>
>> In addition, since the positron range was deactivated by default,
>> I modified the source code to get the positron range.
>>
>> However, even though ion source (37 82 0 0) was used,
>> the positron range was little bit different from Gate 5.0 and
>> also from the reference paper (Levin, Calculation of positron
>> range..., PMB, 1999).
>>
>> I guess this might be a problem with physical model at low energy.
>>
>>
>> One more, I can't use parameterization on batch mode.
>> For example, "Gate -a nZ 37 -a nA 82<  sim.mac".
>> "Gate -a nZ 37 -a nA 82 sim.mac" is working, though.
>>
>>
>> Thank you,
>> MJ
>>
>> //=================================================
>> //  MinJae Park, Ph.D.
>> //
>> //  Johns Hopkins University
>> //  School of Medicine, Dept of Radiology
>> //  Division of Medical Imaging Physics
>> //
>> //  DialTo:+1-443-287-2005 (Office)
>> //  MailTo:MJ at ToTi.us, MJ at JHMI.edu
>> //
>> //  "You see, But you do not Observe"  - Sherlock Holmes -
>> //=================================================
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>