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

[Stathis Kamperis]

Hi Hermann,

thanks for caring. I've already looked at the benchRT/ example and the
photon dose distribution doesn't look correct either (the one that is
displayed along with the dose distribution from a proton beam).

Best regards,
Stathis

On Tue, Mar 4, 2014 at 5:33 PM, Hermann Fuchs
<hermann.fuchs at meduniwien.ac.at> wrote:
> 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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