[Gate-users] LYSO radioactivity

[Paola Solevi]

Hello,
some additional information concerning my problem with LYSO radioactivity 
modelling:
- when I look at the energy of those events having eventID =-2, the energy 
is 0 and it doesn't follow the spectrum I gave in input

- when I change the amplitude of my DTdistribution the number of 
background counts in the same acquisition time doesn't change. But if I 
change the minX and maxX of the DT distribution, it changes (using the 
same amplitude). The narrower is the range, the higher is the 
number of counts.
And the time of the detected background events is distributed over the 
full acquisition time.

So, what do these parameters stand for?

Thank you very much!
 	Paola


On Fri, 13 Jun 2008, Paola Solevi wrote:

> Hello,
> I want to include LYSO intrinsic radioactivity as noise in my Gate system 
> modelling.
> I measured for my crystals the rate and the energy spectrum of background.
> The measured rate is 300 Bq (over the full spectrum).
> I have normalized the energy spectrum to the acquisition time.
>
> Hence I defined my "noise" in the following way:
> /gate/distributions/name lysotime
> /gate/distributions/insert Flat
> /gate/distributions/lysotime/setMin 0.  s
> /gate/distributions/lysotime/setMax 10. s
> /gate/distributions/lysotime/setAmplitude 300. Bq
>
> /gate/distributions/name lysorad
> /gate/distributions/insert File
> /gate/distributions/lysorad/setUnitX keV
> /gate/distributions/lysorad/setUnitY Bq
> /gate/distributions/lysorad/setFileName LYSOspectrum.dat
> /gate/distributions/lysorad/setColumnX 1
> /gate/distributions/lysorad/setColumnY 2
> /gate/distributions/lysorad/read
>
> /gate/digitizer/name NoiseSingles
> /gate/digitizer/insert singleChain
> /gate/digitizer/NoiseSingles/setInputName Singles
> /gate/digitizer/NoiseSingles/insert noise
> /gate/digitizer/NoiseSingles/noise/setDeltaTDistribution lysotime
> /gate/digitizer/NoiseSingles/noise/setEnergyDistribution lysorad
>
> The Min and Max Time of the time distribution are the extremes of my 
> acquisition time (for example 10 s long).
> The energy is given in keV and since I normalized the spectrum to the 
> acquisition time, the y unit should be Bq.
> Running a very low activity source simulation (1 Bq over the entire the FOV), 
> I was expecting to find out a high noise rate in the Single Tree (I have a 48 
> crystal matrix and I apply the noise to Singles whose depth is the crystal 
> volume). A LET of 50 keV is applied at crystal level.
>
> Is there something wrong in my noise definition?
> Did some user already try successfully to include LYSO radioactivity?
>
> Thank you for you hints,
>
> regards
> 	Paola
> _______________________________________________
> Gate-users mailing list
> Gate-users at lists.healthgrid.org
> http://lists.healthgrid.org/mailman/listinfo/gate-users
>