[Gate-users] Positron range simulation - inconsistency between GATE 8.0/ 9.0 and between source types

[David Sarrut]

Hi !

thanks for reporting on that. Could you please add a summary of your
findings as an issued in the github, please? (you can copy parts of the
emails of course). It helps us a lot to keep track and correct issues.

We run a monthly meeting to discuss issues, maintenance and new features.
Hopefully, someone will look at this soon.

Note also, that we will probably start a new (open) action, in the
following month, dedicated to radionuclide therapy simulations. Your report
will be very helpful.

thanks again for reporting,
David

On Tue, Nov 10, 2020 at 12:49 PM Minh Phuong Nguyen <mipbkhn at gmail.com>
wrote:

> Hi Cassandra,
>
> Thank you for your reply. I use the following standard definition for the
> physics list. I also put the definition of the I-124 point source below.
> How do you set the energy cuts? Do you mean the production threshold:
> https://opengate.readthedocs.io/en/latest/cut_and_variance_reduction_technics.html?highlight=range%20cut#production-threshold
>
> #  P H Y S I C S
> /gate/physics/addPhysicsList emstandard
> /gate/physics/addProcess RadioactiveDecay
> /gate/physics/processList Enabled
> /gate/physics/processList Initialized
>
> # S O U R C E:  I-124
> /gate/source/addSource pointsource
> /gate/source/pointsource/gps/particle ion
> /gate/source/pointsource/gps/ion 53 124 0 0
> /gate/source/pointsource/gps/monoenergy 0. keV
> /gate/source/pointsource/gps/angtype iso
> /gate/source/pointsource/gps/mintheta 0 deg
> /gate/source/pointsource/gps/maxtheta 180 deg
> /gate/source/pointsource/gps/minphi -180 deg
> /gate/source/pointsource/gps/maxphi 180 deg
> /gate/source/pointsource/gps/centre 0 0 0 mm
> /gate/source/pointsource/setActivity 30000000 Bq
>
> Best,
> Minh
>
> On Mon, Nov 9, 2020 at 11:21 PM Cassandra Miller <
> cassandramiller at phas.ubc.ca> wrote:
>
>> Hi Minh,
>>
>> I don't have a solution to your problem, but is it possible that your
>> energy cuts are too high and hence your positrons are stopping too early
>> and depositing all of their energy? Also, what physics list are you
>> using?
>>
>> Best,
>> Cassandra
>>
>> On 2020-11-09 07:27, Minh Phuong Nguyen wrote:
>> > Can anyone help me with this?
>> >  The inconsistency in the positron range simulation with GATE appears
>> > to be an existing problem.
>> > Several related posts in the gate-user archive have not received a
>> > final answer either.
>> >
>> > Minh
>> >
>> > On Thu, Nov 5, 2020 at 10:29 AM Minh Phuong Nguyen <mipbkhn at gmail.com>
>> > wrote:
>> >
>> >> Dear GATErs,
>> >>
>> >> I simulated positron ranges for several isotopes such as F-18 and
>> >> I-124 with GATE. The setup was very simple with a point source at
>> >> the centre of a water environment (20-cm-radius sphere). The sphere
>> >> was that large to make sure that the positrons do not escape the
>> >> water volume.
>> >>
>> >> The obtained mean/max positron range from this simulation was
>> >> shorter than what I found in literature. Then I tested with
>> >> different GATE versions (8.0/ 9.0 with corresponding GEANT4 versions
>> >> as stated in the GATE documentation), and different ways of defining
>> >> the source (ion, e+, fastI124). I observed that the positron range
>> >> result was not consistent when changing these parameters (attached
>> >> figures).
>> >>
>> >> Looking at the range distributions (attached figures), GATE 8.0 with
>> >> ion source produced a lot of annihilations near the decay locations
>> >> (range ~ 0 mm). This was not the case with GATE 9.0 and e+ or
>> >> fastI124 sources.
>> >>
>> >> Does anybody know:
>> >> - why positron range from GATE is shorter than in literature?
>> >>
>> >> - which changes in the new GATE version makes the discrepancy in
>> >> positron range simulation result?
>> >> - what makes the difference in positron range between the ion source
>> >> and other type sources?
>> >>
>> >> Thank you.
>> >> Kind regards,
>> >> Minh Phuong Nguyen
>> > _______________________________________________
>> > Gate-users mailing list
>> > Gate-users at lists.opengatecollaboration.org
>> > http://lists.opengatecollaboration.org/mailman/listinfo/gate-users
>>
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-- 
David Sarrut, Phd
Directeur de recherche CNRS
CREATIS, UMR CNRS 5220, Inserm U1206
Centre de lutte contre le cancer Léon Bérard
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