[Gate-users] Positron range measurement

[Grevillot Loic]

Hello,

From the physics point of view, differences are also likely to come from Geant4 itself (Gate being only a Geant4 application), so if different stopping power table were used for example.
It could also depend on how you score the dose deposition (pre or post step point or random), how materials were/are defined, simulation parameters (cut, etc.), scoring resolution, etc.

Hope this help.
Best,
Loïc



From: Gate-users [mailto:gate-users-bounces at lists.opengatecollaboration.org] On Behalf Of Rukiah
Sent: Tuesday, February 07, 2017 3:29 AM
To: Gate-users
Subject: [Gate-users] Positron range measurement


 Hi all,

I am working with vGATE7.2 to measure positron range for F-18,O-15 and C-11 in water, bone and lung and comparing my results with “Analytical positron range modelling in heterogeneous media for PET Monte Carlo simulation” by Lehnert, 2012 which used GATE v5. However the positron range measurements seems a little bit difference with up to 24% for O-15 in bone. For the information, the physics process used is the same as Lehnert,2012 which are electronionization, Bremstrahlung, multiple scattering and positron annihilation.

I belief that the difference is from the coding evolution itself between GATE v5 and vGATE7.2. Even I can't find the coding for GATE v5,  I came into this conclusion when I found out that the measurement is different when I comparing  physics process coding between GATE v7.2 userguide (http://wiki.opengatecollaboration.org/index.php/Users_Guide_V7.2) and an example macro file from vGATE 7.2. Coding from vGATE 7.2 example seems more general and common (ionisation and Bremstrahlung) that leads to a longer range. However I need experts to clarify this.
I also wonder if the type of source (ion, particle) also contributed into this difference.
Thank you.


Physics Process

GATE Userguide_V7.2

VGATE Example

Ionisation

/gate/physics/addProcess ElectronIonisation e+

/gate/physics/addProcess ElectronIonisation e-

/gate/physics/processes/ElectronIonisation/setModel StandardModel e-

/gate/physics/processes/ElectronIonisation/setModel StandardModel e+


/gate/physics/addProcess ElectronIonisation



/gate/physics/processes/ElectronIonisation/setModel StandardModel e-

/gate/physics/processes/ElectronIonisation/setModel StandardModel e+


Bremmsstrahlung

/gate/physics/addProcess Bremsstrahlung e-

/gate/physics/addProcess Bremsstrahlung e+

/gate/physics/processes/Bremsstrahlung/setModel
StandardModel e-

/gate/physics/processes/Bremsstrahlung/setModel StandardModel e+


/gate/physics/addProcess Bremsstrahlung



/gate/physics/processes/Bremsstrahlung/setModel StandardModel e-

/gate/physics/processes/Bremsstrahlung/setModel StandardModel e+


PosAnnihil

/gate/physics/addProcess PositronAnnihilation e+

/gate/physics/addProcess PositronAnnihilation e+


Scattering

/gate/physics/addProcess eMultipleScattering e+
/gate/physics/addProcess eMultipleScattering e-


/gate/physics/addProcess MultipleScattering e+
/gate/physics/addProcess MultipleScattering e-






Rukiah
PhD
The University of Sydney
Australia


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