[Gate-users] MU and bad_alloc

[catarina veiga]

Hi,

Thanks for the answer, once again it was very useful.
I am a medical physics MSc student and am currently doing my research
project in proton therapy, using GATE to reproduce a treatment plan.

"Using all these parameters correctly allows for MU to absolute number of
protons conversion.
As all factors are constant except SP, in GATE you can currently get a
number of protons which is proportional to the absolute number of protons."

I have the MU for each beam energy and total MU for the radiation field.
The expression found on the .cc file you meantioned before gives the
absolute number of protons for the energy and MU give, or a proportional
value? I cannot tell if by weight you mean absolute MU or can be just
something proportional to the MU, and so the value is also only
proportional.

double GateSourceTPSPencilBeam::ConvertMuToProtons(double weight, double
energy)
{
double K=37.60933;
double
SP=9.6139E-09*pow(energy,4)-7.0508E-06*pow(energy,3)+2.0028E-03*pow(energy,2)-2.7615E-01*pow(energy,1)+2.0082E+01*pow(energy,0);
double PTP=1;
double Gain=3./(K*SP*PTP*1.602176E-10);
return (weight*Gain);
}

Regards,
Catarina Veiga

On Wed, Jun 15, 2011 at 9:08 AM, Loic Grevillot <loic.grevillot at gmail.com>wrote:

> Hi,
>
> I do not have precise reference on it, as it was based on a discussion with
> a manufacturer, but you might find it in medical physics books.
>
> But the conversion it quite simple:
> A MU is defined as a number of nC collected in the Ionization Chamber (IC),
> which is filled with air.
> SP corresponds to proton stopping power in air and it is based on a fit
> from ICRU data.
> K is a constant which depends on the mean energy loss (W) to create an
> electron/hole pair.
> PTP are the temperature and pression corrections.
>
> Using all these parameters correctly allows for MU to absolute number of
> protons conversion.
> As all factors are constant except SP, in GATE you can currently get a
> number of protons which is proportional to the absolute number of protons.
>
> It is always interesting to know who is using GATE and for which purpose.
> Could you describe a bit more?
>
> Best Regards,
>
>
> Loïc Grevillot, Ph.D. Student
> PARTNER project, CERN
>
> IBA Particle Therapy / Creatis-LRMN
> Tel (IBA):         +32 10 487 729
>
>
>
> 2011/6/14 catarina veiga <catarinavveiga at gmail.com>
>
>> Thanks for the answer. It was very useful.
>> From what I see on the .cc you have a function that reads the beam MU and
>> energy and converts to number of protons. Can you indicate me any reference
>> to the equation used, like any article were I can find information of it?
>> Kind regards,
>> Catarina Veiga
>>
>>
>> On Tue, Jun 14, 2011 at 10:18 AM, Loic Grevillot <
>> loic.grevillot at gmail.com> wrote:
>>
>>> Dear Catarina,
>>>
>>> I think you should move to Gate V6.1, with Geant4.9.4, because many bugs
>>> should be corrected.
>>> For pencil beams (of protons, but also with any particle you like), 2 new
>>> sources have been added:
>>> - "GateSourcePencilBeam" to define a single pencil beam
>>> - "GateSourceTPSPencilBeam" to define a pencil beam treatment plan
>>> Details are available in the documentation, in the bottom of this page:
>>> http://wiki.opengatecollaboration.org/index.php/Users_Guide_V6.1:Source
>>> You should try also examples "Novice_4" and "Novice_5" from
>>> "examples/example_Radiotherapy" directory.
>>> MU are converted into proton number based on proton stopping power in air
>>> (see "GateSourceTPSPencilBeam.cc") .
>>>
>>> Hope this help!
>>>
>>> Loïc Grevillot, Ph.D. Student
>>> PARTNER project, CERN
>>>
>>> IBA Particle Therapy / Creatis-LRMN
>>> Tel (IBA):         +32 10 487 729
>>>
>>>
>>>
>>> 2011/6/13 catarina veiga <catarinavveiga at gmail.com>
>>>
>>>> Dear users,
>>>>
>>>> I am trying to use GATE on my personal computer to acquire dose
>>>> deposited in
>>>> a proton treatment plan. I need some good accuracy in my calculations,
>>>> but
>>>> for some of my simulations I keep having the simulation aborting, with
>>>> the
>>>> error std bad_alloc. I did some research and understand that this is
>>>> related
>>>> with memory problems. Is there any way to overcome this kind of issues,
>>>> without having to reduce the number of events?
>>>>
>>>> Also, I use GATE V5 to do my simulations. I read that on new version V6
>>>> there are some improvements in definition of a TPS pencil beam source.
>>>> In
>>>> particular, I am interested in how the conversion of MU to number of
>>>> particles has been developped (for protons). Can you inform me of the
>>>> name
>>>> of the files that have the C++ for this so I can take a look at the
>>>> code?
>>>>
>>>> Kind regards,
>>>> Catarina Veiga
>>>> _______________________________________________
>>>> Gate-users mailing list
>>>> Gate-users at lists.opengatecollaboration.org
>>>> http://lists.opengatecollaboration.org/mailman/listinfo/gate-users
>>>>
>>>
>>>
>>
>