[Gate-users] Unrealistic value of max dose with photon beams and a water phantom

[Hermann Fuchs]

Hello,

indeed your values are off.
There is an example within Gate which does what you need to do.
Look into benchmarks, benchRT.

If you have any questions, do not hesitate to ask.

Cheers,
Hermann

Am 04.03.2014 16:06, schrieb Stathis Kamperis:
> Hello again folks,
>
> if I have a water tank 50x50x50 cm and I attach a dose actor to it and
> the resolution of the dose actor is 1 1 50 and the beam comes along
> the z-axis, doesn't that mean that 1 unit in my dose actor corresponds
> to 1 cm of depth ?
>
> Here is a plot with 6, 15, 18, 25 MeV beams from a 10x10cm^2 field at
> SSD=100cm. The depth of maximum dose is wayyy off compared to the
> values in my books. I understand that I'm not simulating the whole
> head of the linear accelerator, but aren't the values awfully out of
> scale? 3cm for 6 MeV ?  8cm for 18 MeV ?
>
> I'd *really* appreciate any insight. I'm using Gate for my thesis and
> unless I give a very very good explanation why those values are so
> much off scale or even better fix the problem, I'll have to use some
> other software :(
>
> Best regards,
> Stathis
>
> http://dl.dropboxusercontent.com/u/25202446/photon-dose-depth.png
>
>
> On Tue, Jan 28, 2014 at 10:07 PM, Stathis Kamperis <ekamperi at gmail.com> wrote:
>> Dear GATE users,
>>
>> I'd like to reproduce the plot at the 5th page of the following presentation:
>>
>> http://www.opengatecollaboration.org/sites/opengatecollaboration.org/files/Talk9-GATE_RT.pdf
>>
>> I'm using the benchRT/gamma.mac as the basis of my experiments. I have
>> 2 questions so far:
>>
>> 1. Why do I get my dose max at ~8.5cm of depth, instead of a much
>> smaller depth as shown in the presentation ?
>> (I've added: /gate/actor/doseDistribution/enableDose true to gamma.mac)
>>
>> 2. Why even though I add:
>> /gate/actor/doseDistribution/normaliseDose true
>>
>> I still get unnormalized values of dose?
>>
>> Best regards,
>> Stathis
>>
>> P.S. Sorry for my naive questions; I'm just getting started.
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