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<font size="-1"><font face="Arial">Hello Hongwei,<br>
<br>
the sensitivity for the ECAT 962 HR+ was measured as 6650 cps/MBq
(center FOV) and 7180 cps/MBq (10 cm off-center FOV) according to NEMA
NU2-2001.<br>
Hope this helps,<br>
Bjoern<br>
</font></font><br>
Hongwei Ye wrote:
<blockquote
cite="mid:OFE8CD8729.D79F0848-ON86257436.007A03A3-86257436.007F9E0C@TMRIUSA.COM"
type="cite"><br>
<font face="sans-serif" size="2">Dear All,</font>
<br>
<br>
<font face="sans-serif" size="2">I'm wondering if there is any way to
turn off the attenuation in GATE (because I'd like to use a simulation
without attenuation in reconstruction). </font>
<br>
<br>
<font face="sans-serif" size="2">What I did right now is to use "Air"
to replace "Water" (or something else) for the object material.
But I met a problem here:</font>
<br>
<br>
<font face="sans-serif" size="2">I have tested two simulations: same
objects with same activity, same scan time, but simulation 1 is made by
"Air" and simulation 2 is made by "Water". Guess what
I got? Simulation 2 (13920 counts) had more coincidences than
simulation
1 (8646 counts) even if simulation 2 was supposed to be attenuated more
by water. (I attached .mac file here)</font>
<br>
<br>
<font face="sans-serif" size="2">Can anyone explain this phenomena or
guide me how to turn off the attenuation ? Should I use "Vacuum"
instead of "Air" and set up "back to back gamma source"?
</font><br>
<br>
<font face="sans-serif" size="2">One more question is about the
sensitivity:
what is its range for ECAT 962 system? By roughly calculating, I got
20~50
cps/kBq depending on different objects. It seems to me those number are
too high.</font>
<br>
<br>
<font face="sans-serif" size="2">Thanks a lot.</font>
<br>
<br>
<font face="sans-serif" size="2">Regards,</font>
<br>
<font face="sans-serif" size="2">Hongwei</font>
<br>
<br>
<br>
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