[Gate-users] Fixed Forced Detection Actor

[Simon Rit]

Hi,

On Mon, Nov 28, 2016 at 2:00 PM, Triltsch, Nicolas <nicolas.triltsch at tum.de>
wrote:

> Hey everyone,
>
> I have three questions concerning the fixed forced detection actor(ffda):
>
> 1) As output one can generate e.g. primary.mha, compton.mha, rayleigh.mha
> and total.mha images. In the GATE wiki it states, that primary + compton +
> rayleigh = total. But if I compare the two images they are different! Why?
> (total.mha image was flatfield corrected by default; primary, compton and
> rayleigh weren't, so I used the flatField.mha to correct them before the
> comparison with total.mha)
>
 I checked and there is a bug in the total filename. However, it does not
use the flat field but rather one step was forgotten (accounting for the
total number of particles in the simulation). I must admit that I never use
that output in practice, hence the bug. This fix
<https://github.com/OpenGATE/Gate/commit/988f886133ee741eeca692df027e7786e025c7bc>
should correct that.

>
> 2) For the ffda the source needs to be focused. Why is that necessary?
>
Because ffda uses RTK <http://openrtk.org/> for deterministic computation
and RTK is working for point sources.


> 3) One output image is called secondary.mha. First, I thought this image
> would represent secondary scatter events. But in the GATE wiki it says that
> secondary = compton + rayleigh. Is their a way to obtain a secondary
> scatter (multiple scatter) image?
>
It used to be possible but I think we have removed it to "minimize" the
number of options. You can try (but I don't guarantee it works) to add a
line in the code, e.g. around line 57 of GateFixedForcedDetectionActor.cc:
mPerOrderImagesBaseName="order";
It will then create an image of the form "orderRayleigh0004_order02.mha"
for the second order of the rayleigh projection number 4.
Simon



>
>
> I would appreciate any help!
>
> Nico
>
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