[Gate-users] linear accelerator simulations (Nicollas Goncalves Cavedini)

Thu Sep 3 14:17:56 CEST 2020

Dear Nicollas,

To perform your linac Monte Carlo simulation I think you need to perform
the following steps :

1. Define the correct electron beam parameters (spatial
distribution/average energy). Assuming you have a correct geometry model,
you need to choose correct cut-off values for each of your simulated parts
(linac/water phantom).

2. Compare normalized dose distributions of the simulation (profiles/PDD)
to normalized measured dose distributions for many radiation fields
starting with the 10x10 cm2 reference field. You have to reproduce in your
simulation the setup used for the measurements.

3. adjust your model to get the best accuracy.

4. according to the calibration conditions (for example 1Gy at 10 cm depth)
you can determine the corresponding number of simulated primary particles
needed to get this dose at the indicated depth. The unit number or the
irradiation time will be equivalent to the number of simulated primary
histories.

Regards.

--
Zakaria Aboulbanine

Le jeu. 3 sept. 2020 à 12:37, <
gate-users-request at lists.opengatecollaboration.org> a écrit :

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> Today's Topics:
>
>    1. Too much Randoms in NECR test (Martin Sower)
>    2. Simulation stuck at geometry initialization (Khalid Hussain)
>    3. linear accelerator simulations (Nicollas Goncalves Cavedini)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 2 Sep 2020 17:47:29 +0100
> From: Martin Sower <melkatib1 at gmail.com>
> To: gate-users at lists.opengatecollaboration.org
> Subject: [Gate-users] Too much Randoms in NECR test
> Message-ID:
>         <
> CAHrTDnO8O74fQEP+jRgO+o3GedgsucMoCcV7BYg6FAk5jFWRpg at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Dear Gaters,
>
>
> I am trying to validate my Biograph mCT model, and I am stuck in the
> NEMA-07 NECR test;
>
> The problem is that I am getting too much Randoms that leads to low of NECR
> peak than other similar published studies; This issue has been reported
> previously by many other Gate users;
>
> SIMULATION DETAILS:
> ==================
> I am simulating the NEMA Phantom with a line source filled with an activity
> concentration of 30 kBq/ml (calculated by dividing the total activity of
> 660 MBq by the Phantom volume); This activity concentration has been taken
> from "Jackoby et al. 2011" article, which corresponds to the NECR peak of
> 180 kcps from the experiment; I am getting a poor NECR value of about 60
> kcps at this activity;
> The Randoms rate am getting is about 85% of total coincidences counts;
> I tried the modification of dead times and pileup values but the Randoms
> count is always too high;
>
>
> PLEASE if somebody has well done the NECR test for the Biograph mCT, mMR or
> any other PET, and has solution or advices regarding this issue of Randoms,
> your help will be greatly appreciated;
>
>
> Thank you in advance.
> Martin Sower
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>
> Message: 2
> Date: Wed, 2 Sep 2020 22:24:02 +0500
> From: Khalid Hussain <khalidhussain1134 at gmail.com>
> To: gate-users <Gate-users at lists.opengatecollaboration.org>
> Subject: [Gate-users] Simulation stuck at geometry initialization
> Message-ID:
>         <
> CAFjakMKukOvMgG6DcGanGbxzdrf8dzmcTf_yGeuhBG487JowcQ at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Dear Gate users,
>
> My simulation stuck at geometry initialization in vGate 8.2, I have tested
> the geometry by expanding in two dimensions and it seems okay for all
> combinations but stuck when using full geometry in 3D.
>
> Please see below script of suspected part of geometry.
>
>
> ############################
> # LOW ENERGY HIGH RESOLUTION COLLIMATOR #
> ############################
>
> # C O L L I M A T O R
>
> /gate/SPECThead/daughters/name collimator
> /gate/SPECThead/daughters/insert box
> /gate/collimator/geometry/setXLength 59.1 cm
> /gate/collimator/geometry/setYLength 44.5 cm
> /gate/collimator/geometry/setZLength 4.0 cm
> /gate/collimator/placement/setTranslation 0. 0. -3.8 cm
> /gate/collimator/setMaterial Air
> /gate/collimator/attachPhantomSD
> /gate/collimator/vis/forceWireframe
> /gate/collimator/vis/setColor white
>
>
> ## Insert upper boundary of hole
>
> /gate/collimator/daughters/name hole
> /gate/collimator/daughters/insert box
> /gate/hole/geometry/setXLength 0.17 cm
> /gate/hole/geometry/setYLength 0.17 cm
> /gate/hole/geometry/setZLength 0.02 cm
> /gate/hole/placement/setTranslation 0. 0. 0. cm
> /gate/hole/setMaterial Lead
> /gate/hole/vis/forceWireframe
> /gate/hole/vis/setColor blue
> ## Insert lower boundary of hole
>
> /gate/hole/daughters/name lowerB
> /gate/hole/daughters/insert box
> /gate/lowerB/geometry/setXLength 0.15 cm
> /gate/lowerB/geometry/setYLength 0.15 cm
> /gate/lowerB/geometry/setZLength 0.02 cm
> /gate/lowerB/placement/setTranslation 0. 0. 0. cm
> /gate/lowerB/setMaterial Air
> /gate/lowerB/vis/forceWireframe
> /gate/lowerB/vis/setColor green
>
> # FILL THE WHOLE COLLIMATOR WITH SEPTA-HOLE
> /gate/hole/repeaters/insert cubicArray
> /gate/hole/cubicArray/setRepeatNumberX 347
> /gate/hole/cubicArray/setRepeatNumberY 261
> /gate/hole/cubicArray/setRepeatNumberZ 100
> /gate/hole/cubicArray/setRepeatVector 0.17 0.17 0.04 cm
>
>
>
> Any help is highly appreciated.
>
> Thanks and regards
> Khalid
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> ------------------------------
>
> Message: 3
> Date: Wed, 2 Sep 2020 15:22:47 -0300
> From: Nicollas Goncalves Cavedini <nicollas.cavedini at acad.pucrs.br>
> To: gate-users <Gate-users at lists.opengatecollaboration.org>,
>         david.boersma at acmit.at
> Subject: [Gate-users] linear accelerator simulations
> Message-ID:
>         <CAMTcvvb3xRWUg36B2bxkZ7+X=
> i8uPMHxvdNn3_VdyO2FFFDRFA at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Dear GATE community,
>
> I am master's student and I am trying to validade the GATE software for
> photon therapy 6 MV radiotherapy planning at the hospital in Porto Alegre,
> Brazil. I modeled the linear accelerator with a 40x40x40 cm³ cubic water
> phantom. I have the PDP values of the linear accelerator and I would like
> to know how I can perform the calibration with the simulation.
>
> I would also like to set up a treatment plan with monitor units and
> different gantry positions, how can I do this?
>
> *Best regards,*
>
> *Nícollas Gonçalves Cavedini*
> Bachelor of Medical Physics (PUCRS)
> Master's Student in Electrical Engineering - PPGEE (PUCRS)
> CV: http://lattes.cnpq.br/7248406497106855
> Contact: +55 (51) 99922-9957
> Porto Alegre, Brazil.
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