[Gate-users] Question regarding creating cold spot on NEMA IQ phantom using Gate_v6.1

[山中 琢]

Hello Gaters,

I'm trying to use the NEMA IQ phantom in the example file of
"example_PHANTOM_SOURCE" folder.
Although I was able to use the phantom, there was no example to set the source.

I was trying to set the background activity inside the body phantom,
but there seems to be no way to set the source with the shape of
half(or quarter)-circle cylinder as is the case with the phantom
geometry.
I tried to use the Forbid or confine command to disable the activity
in the unwanted area, but even though I tried many ways, I have no
idea how those commands works.

I found the past questions regarding similar problem which I copied at
the end of this e-mail, and tried that way... didn't work. Maybe
because of the Gate version difference...

Here is some part of my phantom and source code.

If there are anyone who have tried the NEMA IQ test, I would be very
glad to show me the macro of the source part.

Taku

# Water in Phantom
/gate/outershell1/daughters/name upperinterior
/gate/outershell1/daughters/insert cylinder
/gate/upperinterior/placement/setTranslation 0.0 0.0 0.0 cm
/gate/upperinterior/geometry/setRmax 14.7 cm
/gate/upperinterior/geometry/setRmin  0.0 cm
/gate/upperinterior/geometry/setHeight 21.4 cm
/gate/upperinterior/geometry/setPhiStart 0. deg
/gate/upperinterior/geometry/setDeltaPhi 180. deg
/gate/upperinterior/setMaterial Water
/gate/upperinterior/vis/forceWireframe
/gate/upperinterior/vis/setColor blue

/gate/NEMA_IQ/daughters/name	BG1
/gate/NEMA_IQ/daughters/insert	cylinder
/gate/BG1/placement/setTranslation	0.0 -3.5 0.0 cm
/gate/BG1/geometry/setRmax		14.71 cm
/gate/BG1/geometry/setHeight 	21.5 cm
/gate/BG1/setMaterial		Water
/gate/BG1/vis/disable

/gate/BG1/daughters/name cold1
/gate/BG1/daughters/insert cylinder
/gate/cold1/placement/setTranslation 0.0 0.0 0.0 cm
/gate/cold1/geometry/setRmax 14.7 cm
/gate/cold1/geometry/setHeight 21.4 cm
/gate/cold1/geometry/setPhiStart 180. deg
/gate/cold1/geometry/setDeltaPhi 180. deg
/gate/cold1/setMaterial	Water
/gate/cold1/vis/disable

# BG Source
/gate/source/addSource				upperinterior
/gate/source/upperinterior/gps/centre	0. -3.5 0. cm
/gate/source/upperinterior/setActivity  5000. becquerel #5.3kBq/cc
/gate/source/upperinterior/gps/particle	e+
/gate/source/upperinterior/gps/energytype	Fluor18
/gate/source/upperinterior/gps/angtype	iso
#/gate/source/upperinterior/gps/mintheta	0. deg
#/gate/source/upperinterior/gps/maxtheta 180. deg
/gate/source/upperinterior/setForcedUnstableFlag	true
/gate/source/upperinterior/setForcedHalfLife		6586 s
/gate/source/upperinterior/gps/type		Volume
/gate/source/upperinterior/gps/shape	Cylinder
/gate/source/upperinterior/gps/radius	14.7 cm
/gate/source/upperinterior/gps/halfz	10.7 cm
/gate/source/upperinterior/gps/Forbid	sphere28in
/gate/source/upperinterior/gps/Forbid	sphere37in
/gate/source/upperinterior/gps/Forbid		cold1
/gate/source/upperinterior/gps/confine	BG1_P

----------------------------------
Date: 2010-03-19 16:27:05 GMT (1 year, 43 weeks, 2 days, 9 hours and
20 minutes ago)

Dear All,

I also encountered this problem while implementing the NEMA IQ phantom.
My solution was this (validated in Gate5):
Suppose that we have a hot volume Hot_P, which also has two embedded
(i.e. daughter volume) cold regions Cold1_P, Cold2_P:

/gate/some_mother_volume/name Hot
...
/gate/Hot/daughters/name Cold1
...
/gate/Hot/daughters/name Cold2
...

Define the source distribution with the same geometry than Hot_P, and
confine it to Hot_P:

/gate/source/addSource HotSrc
...
/gate/source/HotSrc/gps/confine Hot_P

The trick is that Gate will confine it only to Hot_P minus the daughter
volumes, i.e. the to desired hot volume.

Hope this helps.

cheers,
  Gergely

---
Gergely Patay
  physicist
Mediso Medical Imaging Systems Ltd.
Hungary

> Dear All,
>
> Is it possible to define more than one cold region with Gate5 ?
> My problem is when I define 2 cold regions in 1 volume, it seems to be
> ok in a first time :
>
> Confirming activity forbidden in volume 'cold1_P'...
>   Activity forbidden in volume 'cold1_P' confirmed
> Confirming activity forbidden in volume 'cold2_P'...
>   Activity forbidden in volume 'cold2_P' confirmed
>
> But when I visualize source position with the visualization source
> tool and also in root output file, just the last cold source (cold2)
> is taken into account and not the both.
>
> Any suggestions appreciated,
>
> Best regards,
>
> Nadège Anizan
> Phd student
> INSERM, Nantes
> France


-- 
Hokkaido University,  Graduate school of medicine, medical physics and
engineering M2
Taku Yamanaka

takuyama at med.hokudai.ac.jp
--