[Gate-users] Re: FW: Difference in energy spectrum for first and second event in cylindrical PET system

Irène Buvat buvat at imed.jussieu.fr
Wed Aug 29 17:32:54 CEST 2007

>Hi Paul and Yuxuan,
>Following your suggestions, I took a closer look at the energy histogram
>of the delayed coincidences by looking at the delays.dat output file.
>As Paul said, the order of the singles in a random coincidence is always
>that the early single is the first half and single 2 (the later one) is
>always the second half.  In the delays file, the two singles should be,
>by definition, just singles and thus they should exhibit an identical
>energy spectrum.  This is not what I see when I look at the data (see
>attached energy histogram).  In my data, single 1 has a different energy
>spectrum than single 2.  The only real difference between the two
>singles is that single 1 is 1 microsecond earlier than single 2.  I have
>no idea why the two singles in the delays file should have different
>spectra, so any additional insight you could offer into this would be
>Andrew Goertzen
>Department of Radiology
>University of Manitoba
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Irene Buvat, PhD
Equipe "Imagerie de la perfusion et des échanges moléculaires"
CHU Pitié Salpêtrière
91 Boulevard de l'Hôpital
75634 Paris Cedex 13
Tel : 01 53 82 84 19
Fax : 01 53 82 84 48
email : buvat at imed.jussieu.fr

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