[gate-users] cylindricalPET

[Fernando Rannou]

Would you please send all your macros in a tar file so
I can run it myself.

Fernando


On Mon, 2005-07-18 at 17:30 -0600, Yun Dong wrote:
> Hi Fernando,
> Thanks for your help. I have tried that the gamma ray go straight into 
> panels, and I also increase the activity to 100M Bq, but the result 
> seem be same till now. I am afraid that the problem would not be from 
> my setting but the GATE. Thanks.
> 
> Yun
> 
> ----- Original Message -----
> From: Fernando Rannou <rannou at diinf.usach.cl>
> Date: Monday, July 18, 2005 12:23 pm
> Subject: Re: [gate-users] cylindricalPET
> 
> > Hi Yun,
> > you could try to "focus" the backtobacks
> > into the panels, that is modify
> > 
> > /gate/source/twogamma/gps/mintheta 0.deg 
> > /gate/source/twogamma/gps/maxtheta 180.deg
> > /gate/source/twogamma/gps/minphi 0. deg
> > /gate/source/twogamma/gps/maxphi 360. deg
> > 
> > such that they always go in the direction of the detectors.
> > I have the feeling that you just have a sensitivity problem,
> > in the sense that the solid angle of your scanner is so small that 
> you
> > need a lot, lot of events to get some coincidences. That would
> > explain why you get some coincidences when you have more panels.
> > So try to shoot the gammas straight into the detectors.
> > 
> > 
> > Fernando
> > 
> > 
> > On Mon, 2005-07-18 at 16:23 -0500, Yun Dong wrote:
> > > Hi Fernando,
> > > 
> > > Thanks for your reply. I give my some configures of simulation 
> here:
> > > 
> > > Geometry: ~250mm*175mm dual-panel, distance between them is 50mm
> > > # P H Y S I C S
> > > /gate/physics/gamma/selectCompton standard
> > > /gate/physics/gamma/selectPhotoelectric standard
> > > /gate/physics/gamma/selectRayleigh lowenergy
> > > /gate/physics/setElectronCut 300. cm
> > > /gate/physics/setXRayCut 1. GeV
> > > /gate/physics/setDeltaRayCut 1. GeV
> > > # D I G I T I Z E R
> > > /gate/digitizer/Singles/insert adder
> > > /gate/digitizer/Singles/insert readout
> > > /gate/digitizer/Singles/readout/setDepth 1
> > > /gate/digitizer/Singles/insert blurring
> > > /gate/digitizer/Singles/blurring/setResolution 0.15
> > > /gate/digitizer/Singles/blurring/setEnergyOfReference 511. keV
> > > /gate/digitizer/Singles/insert thresholder
> > > /gate/digitizer/Singles/thresholder/setThreshold 250. keV
> > > /gate/digitizer/Singles/insert upholder
> > > /gate/digitizer/Singles/upholder/setUphold 750. keV
> > > /gate/digitizer/Coincidences/setWindow 100. ns
> > > # S O U R C E S
> > > /gate/source/addSource twogamma
> > > /gate/source/twogamma/setActivity 1000000. becquerel
> > > /gate/source/twogamma/setType backtoback
> > > /gate/source/twogamma/gps/particle gamma
> > > /gate/source/twogamma/gps/energytype Mono
> > > /gate/source/twogamma/gps/monoenergy 0.511 MeV
> > > /gate/source/twogamma/gps/centre 0 0 0 mm
> > > /gate/source/twogamma/gps/type Volume
> > > /gate/source/twogamma/gps/shape Sphere
> > > /gate/source/twogamma/gps/radius 0.5 mm
> > > /gate/source/twogamma/gps/confine NULL
> > > /gate/source/twogamma/gps/angtype iso
> > > /gate/source/twogamma/gps/mintheta 0. deg
> > > /gate/source/twogamma/gps/maxtheta 180. deg
> > > /gate/source/twogamma/gps/minphi 0. deg
> > > /gate/source/twogamma/gps/maxphi 360. deg
> > > 
> > > Just now I made some tests with resetting configure in 
> > "benchmarkPET"> coming with GATE package: 
> > > 1. (camera.mac 127L) /gate/head/ring/setRepeatNumber 4 (I also 
> > try 2)
> > > 2. (benchmarkPET.mac 
> > 45L)/gate/output/ascii/setOutFileCoincidencesFlag 1
> > > (enable ascii coincindences output).
> > > Then I find that when two heads, the size of coincindence ascii 
> > output> file is always zero after simulation start. But when 4 
> > heads, the size
> > > increases during the simulation. That's so confusing. 
> > > 
> > > Thank you again.
> > > 
> > > Best Regards
> > > Yun
> > > 
> > > 
> > > 
> > > ----- Original Message -----
> > > From: Fernando Rannou <rannou at diinf.usach.cl>
> > > Date: Monday, July 18, 2005 11:28 am
> > > Subject: Re: [gate-users] cylindricalPET
> > > 
> > > > Hi Yun
> > > > you should get coincidences. Among the questions I would ask are:
> > > > 1) What kind of output are you using? I assume you set the 
> > digitizer> > appropriately to collect coincidences.
> > > > 2) how much activity, for how long?
> > > > 3) are you simulating a positron emitter (of course)?
> > > > 4) How big are the detectors with respect to the FOV?
> > > > 
> > > > Fernando
> > > > 
> > > > 
> > > > 
> > > > On Mon, 2005-07-18 at 12:10 -0500, Yun Dong wrote:
> > > > > Hi everyone,
> > > > > I am just simulating two parallel-panels PET system through
> > > > > cylindricalPET system in GATE. Howver, I never get 
> > coincidences, 
> > > > just> GateSingles. Does it mean that cylindricalPET can never 
> > > > simulate the
> > > > > open two parallel-detector PET system? Dose anybody have 
> > some idesa?
> > > > > Thank you so much.
> > > > > 
> > > > > Best Regards
> > > > > Yun
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