[Gate-users] (no subject)

[David Boersma]

Hi amir bahador yeke dehghan,

In a future version of Gate you may get "absolute dose" by setting a flag that takes care of the rescaling, we have some ideas for implementing that, at least for ion beam therapy. You are not alone! 😊

For now, what I do (with pencil beam ion therapy plans) is to figure out how many particles the TPS prescribes, e.g. nTPS=1e10. Suppose in my simulation I used nMC=1e7 primaries. Then I need to multiply my dose distribution by nTPS/nMC=1e10/1e7=1000 to get the absolute dose.

Often nMC is a number that you choose yourself, so that is easy. If you use the "StopOnScriptActor" then you can obtain the number of primaries from the output of the StatisticsActor.

In pencil beam ion beam therapy, the spot weights are either given in "number of particles" or in "monitor units". The first case makes your life easy, you get nTPS by just adding the spot weights. In the second case you need an energy dependent conversion factor between MU and number of particles. For a treatment plan created for a particular clinic, the medical physicists in that clinic should know this conversion function (usually parametrized with a polynomial), hopefully they can share it with you.

For conventional radiotherapy (with photons) it may not be so easy to figure out "how many particles the TPS prescribes" and you may need to use  a different procedure to scale your dose to the absolute dose. I'm not the right person to help you in that case, hopefully someone else can provide some hints/pointers/explanations.

HTH,
David Boersma


________________________________
Von: Gate-users <gate-users-bounces at lists.opengatecollaboration.org> im Auftrag von amir bahador yeke dehghan <amirbahadordehghan at gmail.com>
Gesendet: Mittwoch, 22. April 2020 11:44:28
An: gate-users at lists.opengatecollaboration.org
Betreff: [Gate-users] (no subject)

Hi everyone
can you guide me how can I obtain absolute dose in Gate RT?
I used dose actor in my code already and have dose, dose uncertainty, Edep and dose squared output.
I try use gamma index criteria and need absolute dose.
thanks for help.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.opengatecollaboration.org/pipermail/gate-users/attachments/20200424/567280bc/attachment.html>