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

[Stathis Kamperis]

Oops, I forgot to link to my .mac file here:

http://dl.dropboxusercontent.com/u/25202446/photons.mac

Best regards,
Stathis

On Tue, Mar 4, 2014 at 5:06 PM, Stathis Kamperis <ekamperi at gmail.com> wrote:
> 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.