[Gate-users] Too much Randoms in NECR test

[Martin Sower]

Dear Gaters,


I am trying to validate my Biograph mCT model, and I am stuck in the
NEMA-07 NECR test;

The problem is that I am getting too much Randoms that leads to low of NECR
peak than other similar published studies; This issue has been reported
previously by many other Gate users;

SIMULATION DETAILS:
==================
I am simulating the NEMA Phantom with a line source filled with an activity
concentration of 30 kBq/ml (calculated by dividing the total activity of
660 MBq by the Phantom volume); This activity concentration has been taken
from "Jackoby et al. 2011" article, which corresponds to the NECR peak of
180 kcps from the experiment; I am getting a poor NECR value of about 60
kcps at this activity;
The Randoms rate am getting is about 85% of total coincidences counts;
I tried the modification of dead times and pileup values but the Randoms
count is always too high;


PLEASE if somebody has well done the NECR test for the Biograph mCT, mMR or
any other PET, and has solution or advices regarding this issue of Randoms,
your help will be greatly appreciated;


Thank you in advance.
Martin Sower
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