[Gate-users] Potential bug report of Edep in DoseActor (Edep always == 1 Mev for any Ion)

Grevillot Loic loic.grevillot at medaustron.at
Mon Mar 8 14:07:44 CET 2021


Hi !

Sorry, I did not have time to go through your macros, but you also said "I did not find the example where DoseActor is used to record energy deposited by ions for dosimetry"

è You can find it under the gitcontrib<https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FOpenGATE%2FGateContrib%2Ftree%2Fmaster%2FGATE-RTion&data=04%7C01%7Cloic.grevillot%40medaustron.at%7C991a8c8daae94bce6fbc08d8e03752cf%7Cadb749e06dfd4f6fbea8cd9f8e0c9b89%7C0%7C0%7C637505876735190754%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=ggXJ1p8887dT%2FsE8jSOOZVsHivOVWG91KQ1M%2FTCNiGw%3D&reserved=0> repository, in DoseActor (scrren-shots below)

è You can find an example of energy to dose conversion validation for ions - further testing include mass-weighting, volume-weighting algorithms, etc. are also available.

[cid:image001.jpg at 01D71424.682C2260] [cid:image002.jpg at 01D71424.682C2260]




[cid:image003.jpg at 01D71424.682C2260]
Best,
Loïc



From: Albert Grace Lieu [mailto:albertnew2018 at gmail.com]
Sent: Saturday, March 6, 2021 1:27 AM
To: Grevillot Loic <loic.grevillot at medaustron.at>; gate-users <gate-users at lists.opengatecollaboration.org>
Cc: Peter Olcott <polcott at reflexion.com>
Subject: Re: Potential bug report of Edep in DoseActor (Edep always == 1 Mev for any Ion)

Hi Loïc,

Thank you very much for actively answering DoseActor related questions in the past ten years. I saw your answers in the GATE archive quite often. I did read through almost all example codes in GATE-RTiON, but I did not find the example where DoseActor is used to record energy deposited by ions for dosimetry.

Here is the problem I have found with Edep in DoseActor, a similar question<https://eur03.safelinks.protection.outlook.com/?url=http%3A%2F%2Flists.opengatecollaboration.org%2Fpipermail%2Fgate-users%2F2009-July%2F003406.html&data=04%7C01%7Cloic.grevillot%40medaustron.at%7C991a8c8daae94bce6fbc08d8e03752cf%7Cadb749e06dfd4f6fbea8cd9f8e0c9b89%7C0%7C0%7C637505876735180759%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=GVfn7d0HY3KvSz1EbfNrBCt9r6FcT%2FbbHW%2FRN1BUIrw%3D&reserved=0> was also asked many years ago. No matter what source I use, like I-131, Lu-177, Edep in DoseActor always returns 1 (Mev) per disintegration. Dose in DoseActor also utilizes the value returned Edep, which leads to a wrong result. I would rather believe that I made a mistake somewhere than think GATE's DoseActor failed in my case.

Could you or any other GATE user have a look at my code? It is self-containt code. You will finish the entire verification in less than 5 minutes. Here is what the GATE code does:

  *   Phantom: 101*101*101 voxelized tissue ( water equivalent) phantom, with a side of 2 mm for each voxel
  *   Source: 10 mm radius sphere voxelized Lu177 source with a side of 2 mm for each voxel, and being placed in the center of the phantom
  *   DoseActor: record dose, Edep, and export a mass image of the phantom (all 3D array)
  *   ProductionAndStoppingActor: record the number of Lu177 generated in each voxel, indicated by Lu177-Stop (3D array)
        According to the user manual, "The unit of edep is MeV and the unit of dose is Gy".

You will also find a python script (result-analysis.ipynb) to do the analysis:

  *   reads dose, edep, mass, and particle-prod
  *   calculate the average energy deposited by a single disintegration.
Thank you very much for any help and verification.

Albert







On Fri, Mar 5, 2021 at 12:48 AM Grevillot Loic <loic.grevillot at medaustron.at<mailto:loic.grevillot at medaustron.at>> wrote:
FYI,
DoseActor validation tests were provided for the GATE-RTiON<https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgate.uca.fr%2Fdownload%2Fgate-rtion&data=04%7C01%7Cloic.grevillot%40medaustron.at%7C991a8c8daae94bce6fbc08d8e03752cf%7Cadb749e06dfd4f6fbea8cd9f8e0c9b89%7C0%7C0%7C637505876735180759%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=Zn97wCKsFa%2BxCi3%2BYO%2F2hLVeY9%2BUf9jOfKAxU3xP1x4%3D&reserved=0> release, in the context of light ion beam therapy under the gitcontrib<https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FOpenGATE%2FGateContrib%2Ftree%2Fmaster%2FGATE-RTion&data=04%7C01%7Cloic.grevillot%40medaustron.at%7C991a8c8daae94bce6fbc08d8e03752cf%7Cadb749e06dfd4f6fbea8cd9f8e0c9b89%7C0%7C0%7C637505876735190754%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=ggXJ1p8887dT%2FsE8jSOOZVsHivOVWG91KQ1M%2FTCNiGw%3D&reserved=0> repository.
The tests can be applied in principle to any GATE release and may help you as a starting point.
It would be nice to increase the collection of tests for other clinical applications such as  yours!

Best,
Loïc



From: Gate-users [mailto:gate-users-bounces at lists.opengatecollaboration.org<mailto:gate-users-bounces at lists.opengatecollaboration.org>] On Behalf Of Albert Grace Lieu
Sent: Freitag, 5. März 2021 05:59
To: gate-users <gate-users at lists.opengatecollaboration.org<mailto:gate-users at lists.opengatecollaboration.org>>
Subject: [Gate-users] Edep returned by DoseActor is about 7 times bigger then hand calculated value

Hi Gate users,

I am validating the validity of DoseActor in GATE for radionuclide dosimetry application. Surprisingly, I found the Edep returned by DoseActor is about 7 times bigger than my hand calculated value, so does the dose returned by DoseActor. I could be wrong, but I double-checked everything I did and had been as prudent as I can before asking for suggestions here.

Here is what I did in GATE:

  *   Phantom: 101*101*101 voxelized tissue ( water equivalent) phantom, with a side of 2 mm for each voxel
  *   Source: 10 mm radius sphere voxelized Lu177 source with a side of 2 mm for each voxel, and being placed in the center of the phantom
  *   DoseActor: record dose, Edep, and export a mass image of the phantom (all 3D array)
  *   ProductionAndStoppingActor: record the number of Lu177 generated in each voxel, indicated by Lu177-Stop (3D array)
        According to the user manual, "The unit of edep is MeV and the unit of dose is Gy".

Here is how I calculate the average of the energy of Lu177 in water, Lu177 is a beta emitter, the range of electron in water is way smaller than 2mm, thus it is stopped where is created. Given the branching ratio of Lu177, on average a single Lu177 disintegration would deposit 134.16 Kev (electrons only) or 162.95 Kev (electrons and gammas).

[RTEmagicC_Lu-177_decays.png.png]

However, when I divide Edep by Lu177-Stop, the energy per Lu177 disintegration returned by DoseActor is ~1.0 Mev, which 7 times bigger than my hand calculated value. Is this an internal issue? I attach my Gate code for your review.


Thanks a lot for your help.
Sincere wishes,
Stay safe and healthy
Albert


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