<div dir="ltr"><div>Interpolation is a good choice, I always use it in practice. I
would not consider denoising because the result is quite smooth already
if you only measure the object scatter.<br>Thanks, I would not have guessed it but it's a "small" object. Compton scatter should take over at this energy with larger objects (intuitively).<br>Simon<br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Jun 28, 2017 at 1:26 PM, Triltsch, Nicolas <span dir="ltr"><<a href="mailto:nicolas.triltsch@tum.de" target="_blank">nicolas.triltsch@tum.de</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
<p>Hi,</p>
<p>Okay, this information is very helpful, because it shows
possibilities for acceleration, for example, using interpolation
or de-noising if the detector resolution is chosen very coarse (20
x 20, as an example.)</p>
<p>You are right, maybe that's the reason. But then I wonder how
they can use very little number of photons even for more complex
test objects in later sections of their paper.</p>
<p>This might be interesting for you: I simulated the scatter signal
behind a water cylinder of 5cm diameter at 60keV and the coherent
scatter signal (0.4% I_0) exceeded the incoherent scatter signal
(around 0.1% I_0).</p>
<p>Cheers,</p>
<p>Nico<br>
</p><div><div class="h5">
<br>
<div class="m_-8831896018024012612moz-cite-prefix">On 06/28/2017 11:41 AM, Simon Rit
wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div>
<div>
<div>Hi,<br>
</div>
There is no denoising and no interpolation. It gives the
result of Poludniowski before intepolation which I think can
easily be done out of Gate.<br>
</div>
I don't know why you need more photons... Are you sure you
have tested the same test case? For example, they have used 60
keV monoenergetic photons which is very favorable because
there is little elastic scattering at this energy (which takes
longer to converge). I also note that they only look behind a
(simple) cubic phantom where it converges faster in my
experience.<br>
</div>
Simon<br>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Wed, Jun 28, 2017 at 11:27 AM,
Triltsch, Nicolas <span dir="ltr"><<a href="mailto:nicolas.triltsch@tum.de" target="_blank">nicolas.triltsch@tum.de</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hello Gate
community, hallo Simon Rit,<br>
<br>
I have a general question to the implementation of the fixed
forced detection algorithm.<br>
<br>
Is there a de-noising step performed at the end of one
simulation run (as reported by Colijn & Beekman 2004 or
Mainegra-Hing & Kawrakow 2008) or does the
implementation follow the fixed forced scheme ( Poludniowski
et al. 2009) where no de-noising step is required, because
scatter is registered at nodal points at the detector
followed by linear interpolation.<br>
<br>
If the latter is used, then I wonder why 10^5 to 10^6
photons are required to obtain low uncertainty images,
because in the mentioned paper they use only 10^3 to 10^4
photons to gain reasonable results.<br>
<br>
Cheers and I appreciate any help!<br>
<br>
Nico<br>
<br>
-- <br>
B.Sc. Nicolas Triltsch<br>
Masterand<br>
<br>
Technische Universität München<br>
Physik-Department<br>
Lehrstuhl für Biomedizinische Physik E17<br>
<br>
James-Franck-Straße 1<br>
85748 Garching b. München<br>
<br>
Tel: <a href="tel:%2B49%2089%20289%2012591" value="+498928912591" target="_blank">+49 89 289 12591</a><br>
<br>
<a href="mailto:nicolas.triltsch@tum.de" target="_blank">nicolas.triltsch@tum.de</a><br>
<a href="http://www.e17.ph.tum.de" rel="noreferrer" target="_blank">www.e17.ph.tum.de</a><br>
<br>
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<br>
<pre class="m_-8831896018024012612moz-signature" cols="72">--
B.Sc. Nicolas Triltsch
Masterand
Technische Universität München
Physik-Department
Lehrstuhl für Biomedizinische Physik E17
James-Franck-Straße 1
85748 Garching b. München
Tel: <a href="tel:+49%2089%2028912591" value="+498928912591" target="_blank">+49 89 289 12591</a>
<a class="m_-8831896018024012612moz-txt-link-abbreviated" href="mailto:nicolas.triltsch@tum.de" target="_blank">nicolas.triltsch@tum.de</a>
<a class="m_-8831896018024012612moz-txt-link-abbreviated" href="http://www.e17.ph.tum.de" target="_blank">www.e17.ph.tum.de</a></pre>
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