[Gate-users] Reducing computing time for realistic (industrial) CT simulations

Tue Feb 11 10:11:02 CET 2014

Hello Maximilien,

we are currently working on an approach that could decrease the computation
time (hopefully by a least 1 order of magnitude). However, this approach
which is based on the forced detection technique, is still in development
and not yet available. In the meantime, try to be sure to avoid any
electron generation.

David

On Fri, Feb 7, 2014 at 3:03 PM, MELISSAS Maximilien (SAFRAN) <
maximilien.melissas-alten at safran.fr> wrote:

>  Dear Gate-users
>
> I am using Gate to simulate a CT acquisition chain (GE tomex L 450) usedfor CT analysisof aeronauticalparts.
>
> The main issue I am facing is computing time, especially if I wantto simulatea full scan (2400 projections atI= 2ma,
> V = 350 kV. (One of) my "test" setup is an epoxy cylinder located 50
> cm from the tube, with the detector at 1m from the tube, if I propagate500 000 (as a benchmark) photons the "user"computingtimes are the following
> :
>
> 31.15 seconds without optimization (Only setting the simulation as /fast/
> to avoid losing one hour computing a 2048x2048 pixels grid)
>
> 30.8 seconds  if I play with MaxStepSize (Actually, if I do /gate/physics
> /SetMaxStepSizeInRegion world  15.0 mm, is the step size reset to a
> normal value when entering another material ? )
>
> 31.71 seconds if I set VRT to 10 (as in the benchmarkCT/vrt example)
>
> This important CPU time makes me fear that I cannot compute nora realistic
>  amount of photon, neither a realistic number of projections, so I needto find
>  some way to reduce computing time while keeping useful informations)
>
> Is-there any option similar to thinning/weighting (but for primaries sinceI am
>  not interested in secondary electrons) to increase luminosity without
>  increasing computing-time?  Is there any other way to reduce the
> simulation time?  Does the vrt increase the weight of a photon hittingthe detector and thus
>  increase virtually the number of photons? (I haven't tried yetto generateimages withthe vrtenabled)
>
>
> Another question, even though the default source is conical, I'd liketo take
>  into account the Gaussian-shape of the X-ray spot, is there advancedsetting of the source in the macros? If not-is
>  there any Cpp example?
>
> A last question, how do I find the history of a hit, when parsing the
> ntuple, can I find information about the hit's history, whether the
> photon has been scattered, and through which material has itbeen propagated?
>
> i.e. how do I make the difference between
>
> 0   0.0116    0.013     -150     0.156        0        0         0
> world_phys initStep
>
>  1    0.433    -4.18      -12     0.156        0      138
> 138 epoxyCylinder_phys Transportation
>
>  2    0.458    -4.42    -3.97     0.156        0     8.02
> 146 CCylinder_phys Transportation
>
>  3    0.482    -4.66     3.97     0.156        0     7.95
> 154 epoxyCylinder_phys Transportation
>
>  4    0.506     -4.9     11.8     0.156 0.000291     7.81
> 162 epoxyCylinder_phys Compton
>
>  5    0.539    -4.87       12     0.156        0    0.216
> 162 world_phys Transportation
>
>  6       22     12.5      150     0.156        0      141       303
> pixel_phys Transportation
>
> And
>
> 0  -0.0249   -0.017     -150     0.114        0        0         0
> world_phys initStep
>
>  1    -4.21    0.707    -11.2     0.114        0      139
> 139 epoxyCylinder_phys Transportation
>
>  2    -4.88    0.823       11     0.114        0     22.2       161
> world_phys Transportation
>
>  3    -9.06     1.55      150     0.114        0      139       300
> pixel_phys Transportation
>
> I guess I should set some actors, but I do not find any clear examples in
> the documentation.
>
>
>
> Thanks for your answers/help,
>
>
>
>  Cheers,
>
> Maximilien
>
>
>
> #
> " Ce courriel et les documents qui lui sont joints peuvent contenir des
> informations confidentielles, être soumis aux règlementations relatives au
> contrôle des exportations ou ayant un caractère privé. S'ils ne vous sont
> pas destinés, nous vous signalons qu'il est strictement interdit de les
> divulguer, de les reproduire ou d'en utiliser de quelque manière que ce
> soit le contenu. Toute exportation ou réexportation non autorisée est
> interdite.Si ce message vous a été transmis par erreur, merci d'en informer
> l'expéditeur et de supprimer immédiatement de votre système informatique ce
> courriel ainsi que tous les documents qui y sont attachés."
> ******
> " This e-mail and any attached documents may contain confidential or
> proprietary information and may be subject to export control laws and
> regulations. If you are not the intended recipient, you are notified that
> any dissemination, copying of this e-mail and any attachments thereto or
> use of their contents by any means whatsoever is strictly prohibited.
> Unauthorized export or re-export is prohibited. If you have received this
> e-mail in error, please advise the sender immediately and delete this
> e-mail and all attached documents from your computer system."
> #
>
> _______________________________________________
> Gate-users mailing list
> Gate-users at lists.opengatecollaboration.org
> http://lists.opengatecollaboration.org/mailman/listinfo/gate-users
>

-- 
David Sarrut, Phd
Directeur de recherche CNRS
CREATIS, UMR CNRS 5220, Inserm U 1044
Centre de lutte contre le cancer Léon Bérard
28 rue Laënnec, 69373 Lyon cedex 08
Tel : 04 78 78 51 51 / 06 74 72 05 42
http://www.creatis.insa-lyon.fr/~dsarrut
_________________________________
 "2 + 2 = 5,  for extremely large values of 2"
_________________________________
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.opengatecollaboration.org/mailman/private/gate-users/attachments/20140211/2ad2bfbc/attachment-0001.html>