[gate-users] Crystal ID and position of Singles in PET

Chen, Yu Yu.Chen at umassmed.edu
Tue Mar 14 22:36:42 CET 2006

Hi, Gaters,

When I try to convert the global position (globalPosX, Y, Z) of Singles in PET
to corresponding rsectorID and crystalID, I found there is discrepancy between
converted crystalID and recorded crystalID, namely, ~10% with -1 (converted - output)
distributed within lower half of the same rsector while ~10% with +1 in upper half.
Here lower, upper are defined along anti-clock-wise (increased azimuthal direction in
X-Y plane).

Has anybody investigated this before?

I am using cylindricalPET geometry and setDepth 1, which means Singles are readout from 
rsector with all pulses in all crystals in that rsector. A singles will take that pulse's
crestalID and position with max energy. So expected discrepancy should be very small
due only to float calculation. Am I right? If yes, what's wrong here?


Yu Chen, Ph.D.
University of Massachusetts Medical School
Division of Nuclear Medicine
55 Lake Avenue North
Worcester, MA 01655-0243
Phone:  (508) 856-6123
Fax:    (508) 856-4572

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