[Gate-users] SENSITIVITY-PET

[Marc Chamberland]

Hi Lorena,

Look at the number of events in any of the Coincidences Root histograms (for example, you could look at the number of events in globalPosX1). That tells you how many coincidences you had.

Matching the sensitivity is very tricky. You'll need to fine tune your digitizer. One thing you'll want to adjust (among others) is the dead time. So try different values and re-run your simulations until you find a match. Unfortunately, there are a lot of options for dead time, so this might be time consuming.

Good luck!

Marc



__________________________

Marc Chamberland, MSc
PhD candidate
Department of Physics
Carleton University
Ottawa (ON)

On Feb 12, 2015, at 06:51, LORENA VAZQUEZ CANELAS <lorena.vazquez at usal.es<mailto:lorena.vazquez at usal.es>> wrote:

Dear Gaters,

I am currently trying to measure the sensitivity of PET. I did my macro according NEMA NU 2-2007 and then the sensitivity is the number of coincidences divided by activity of source.
The data output are in ROOT and so I wrote:
# ROOT OUTPUT FORMAT
/gate/output/root/enable
/gate/output/root/setFileName             ROOT
/gate/output/root/setRootHitFlag          0
/gate/output/root/setRootSinglesFlag      0
/gate/output/root/setRootCoincidencesFlag 1
/gate/output/root/setRootdelayFlag        0

Only active with a 1, because I think it is all that I need to measure the sensitivity.
My problem is that I don't recognize (in ROOT) the value of coincidences. If It is "eventID#", "crystalID#" or other value...
The sensitivity of my PET is 9.5cps/KBq and I use a source 1.8MBq type "twogamma". With my data output (~500cps/KBq) I get nearly 50 times the real value.
Has anyone ever calculated the sensitivity? you know?

Thank you in advance,
Lorena
--

LORENA VÁZQUEZ CANELAS
--
LRI - Datación (Despacho Técnicos)
Calle Espejo, s/n, 37008 - Salamanca (Spain)
TEL: +34 923 294930 ext:4932 email: lorena.vazquez at usal.es<mailto:lorena.vazquez at usal.es>
web: http://campus.usal.es/~lri/<http://campus.usal.es/%7Elri/>

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