[Gate-users] TPSPencilBeam source description

[jbaran]

Hi David,

many thanks for your answer. For now, I will probably stay with the 
p+/MU calibration factor (as a function of energy) which in fact we 
already have. I just needed to know how to incorporate that in source 
description file (as you already explained).

Regarding your comment about the usage of 'setSpotIntensityAsNbIons' 
option:
At that point I use clitkDicomRTPlan2Gate app from VV software as you 
suggested two days ago (I think you can update the VV instalation page 
because you have to change the ITK_TOOLS flag during ccmake procedure as 
it is OFF by default). As far as I understood it creates the Gate 
compatible file with weights (not number of protons) for every spot - 
this is what I already produced. If I understood well you suggest to 
change it to the real number of protons instead of weights. Is it 
possible to produce the plan description with number of ions instead of 
weights by any existing software? Is clitkDicomRTPlan2Gate could do 
that? I haven't seen that option when I used --help flag. Or maybe I 
missed something. I do PhD in Cracow at CCB and I am not sure if the 
facility is similar to the Skandion. :)

Moreover, due to the fact that some of our plans have more than 10^10 
protons, it will be easier for us to use total number of ions and 
weights for every spot, split jobs into several cores as we have cluster 
here and then merge them together rather than run everything at once and 
then eventually normalized it. (besides I don't know if Geant4 constrain 
on maximum number of primaries ~2*10^9 is still valid). Unless there is 
any other way around to do that in a smart way? What is also important 
in our case, the dose is not our main goal, we are looking at the beta 
plus signal for PET-based range monitoring.

Best regards,
Jakub

On 2019-08-21 15:06, David Boersma wrote:
> Hi Jakub,
> 
> Yes, sorry, this is a relatively new (~1 year old) addition to the
> "source properties" in GateSourceTPSPencilBeam.
> 
> We ("GateRTion" crowd) are even thinking about changing it yet again.
> 😊
> 
> If the treatment plans that you work with are specifying the spot
> weights in "number of ions" (option "setSpotIntensityAsNbIons" true),
> then in principle you do not need to worry about this, the monitor
> calibration will be ignored (add a dummy polynomial, maybe you can
> even omit it).
> 
> If it does use MU as a spot weight unit, then during commsissioning of
> your TPS you or your medical physicist colleagues probably had to
> provide tables/curves of N/MU as function of beam energy. A polynomial
> fit to those data would be good first try for a good N/MU calibration
> in the source properties file. Maybe another possibility: fit them
> together with the energy polynomials, if you happen to have a set of
> IDD curves with absolute calibration.
> 
> In older versions of Gate (8.0 and older) the N/MU calibration was
> hardcoded in GateSourceTPSPencilBeam. I made a polynomial fit to that
> calibration function and inserted it in the source properties file of
> the "dosimetry/dosimetry/protontherapy" example:
> 
> https://github.com/OpenGATE/GateContrib/blob/master/dosimetry/dosimetry/protontherapy/data/Source-Properties.txt
> 
> 
> A few years ago, when I was working in Uppsala, I compared this
> function with the measured calibration curve of the Skandion clinic.
> Amazingly, they were completely compatible within the accuracy of the
> measurement. If the treatment machines for which you are going to
> perform simulations are similar to those at Skandion, then I bet that
> you can be optimistic about the similarity of your curve with that
> "standard calibration curve". 😊
> 
> About the planned change to this functionality: right now, only the
> shape of the N/MU curve matters, not the overall normalization factor.
> The spot weights (be it in N or in MU) are effectively renormalized to
> the number of requested primaries: if you request 10 times more
> primaries, then the DoseActor will record a 10 times higher dose. In
> order to compare with TPS dose, you need to rescale the distributions
> with NTPS/NMC. It has been suggested that the dose actor should apply
> this rescaling factor directly (this is technically not so hard, using
> the particle weight). This probably wouldn't affect the source
> properties file, but it would put stronger requirements on the quality
> of the fit that you provide (not only the shape, but the normalization
> will matter too). For the implementation, we need to take care that
> this will work correctly with variable number of primaries (for the
> SaveData functionality of the dose actor, e.g. with "everyNseconds",
> or in combination with the "stop on script" actor).
> 
> HTH,
> 
> David
> 
> -------------------------
> 
> VON: Gate-users <gate-users-bounces at lists.opengatecollaboration.org>
> im Auftrag von jbaran <jbaran at ifj.edu.pl>
> GESENDET: Mittwoch, 21. August 2019 13:18:44
> AN: Gate Users
> BETREFF: [Gate-users] TPSPencilBeam source description
> 
> Dear Gate Community,
> 
> According to the TPSPencilBeam source description
> (http://wiki.opengatecollaboration.org/index.php/Users_Guide:Source#TPS_Pencil_Beam_source)
> 
> I have to provide 9 polynomials. I dealt with all of them. However I
> have a problem to describe the beam monitor calibration in number of
> particles per monitor unit (N/MU). Unfortunately, there is no
> description of that in that example:
> https://github.com/OpenGATE/GateContrib/blob/master/dosimetry/Radiotherapy/example5/data/Source-Properties.txt
> 
> .
> 
> Is anyone have similar problem and could provide the proper way of
> doing
> that.
> 
> All the best,
> Jakub
> 
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