[Gate-users] how to set MU prescription dose lines

Thu May 16 12:03:53 CEST 2013

Hi,

It is true that general_trpd is a shape a bit complex to describe.
I would advise you first to have a look in the help (
http://wiki.opengatecollaboration.org/index.php/Users_Guide_V6.2:Defining_a_geometry),
where the different inputs (X1, X2, Y1, Y2, etc.) are described.

I did not work with it for a long time, but I guess that all lengths: X1,
X2, etc. are described relatively to what you call the center
point  coordinate.

I can also suggest you to use the graphical display and make simple tests,
in order to check that the displacement is as expected: for instance,
create a single trpd, define X1=4cm, X2=5cm and make a translations of +/-4
cm then +/-5cm etc. to check.

Hope this help.

Loïc

*From:* david.sarrut at gmail.com
[mailto:david.sarrut at gmail.com<david.sarrut at gmail.com>]
*On Behalf Of *David Sarrut
*Sent:* Donnerstag, 16. Mai 2013 08:59
*To:* Grevillot Loic
*Subject:* Fwd: [Gate-users] how to set MU prescription dose lines

tu peux éventuellement lui répondre STP (faut mettre la gate-user mailing
list en copie pour garder une trace) ...

merci !

David

---------- Forwarded message ----------
From: *刘斌信件* <golder_time at 163.com>
Date: Wed, May 15, 2013 at 11:43 AM
Subject: Re: [Gate-users] how to set MU prescription dose lines
To: David.Sarrut at creatis.insa-lyon.fr

hi David,

  Thank you very much ,you always  kindly and warmly  offer me help ,I am
so grateful to you .

I'm sorry to that there  another problem  I want to get adive from you. In
the  multileaf collimator  simulation macro file , the shape of leaf is
described as general_trpd, I can't sure relation between the center
point  coordinate postion which is important to translation of leaf  and
the whole  general_trpd  position.

The related macro sentences  are as  below:

/gate/mylinac_MLC_Leaf2_Right/daughters/name mylinac_MLC_Leaf2_Right_trp_sup

/gate/mylinac_MLC_Leaf2_Right/daughters/insert general_trpd

/gate/mylinac_MLC_Leaf2_Right_trp_sup/setMaterial
AcceleratorCollimatorLeafMaterial

/gate/mylinac_MLC_Leaf2_Right_trp_sup/geometry/setX1Length 16 mm

/gate/mylinac_MLC_Leaf2_Right_trp_sup/geometry/setX2Length 16 mm

/gate/mylinac_MLC_Leaf2_Right_trp_sup/geometry/setX3Length 162.60 mm

/gate/mylinac_MLC_Leaf2_Right_trp_sup/geometry/setX4Length 162.60 mm

/gate/mylinac_MLC_Leaf2_Right_trp_sup/geometry/setY1Length 3 mm

/gate/mylinac_MLC_Leaf2_Right_trp_sup/geometry/setY2Length 3 mm

/gate/mylinac_MLC_Leaf2_Right_trp_sup/geometry/setZLength  31.77 mm

/gate/mylinac_MLC_Leaf2_Right_trp_sup/geometry/setTheta    66.567 deg

/gate/mylinac_MLC_Leaf2_Right_trp_sup/geometry/setPhi  0 deg

/gate/mylinac_MLC_Leaf2_Right_trp_sup/geometry/setAlp1     0 deg

/gate/mylinac_MLC_Leaf2_Right_trp_sup/geometry/setAlp2     0 deg

/gate/mylinac_MLC_Leaf2_Right_trp_sup/placement/setTranslation
-38.380.0 21.615 mm

I know the center postion of mylinac_MLC_Leaf2_Right_trp_sup is same to
mylinac_MLC_Leaf2_Right's central position  before translating, however , I
am not clear about connections between  center point of general_trpd and
Xlength 、Ylength、Zlength，Only know the relation  I will properly set the
placement of leaf in MLC geometry.

 sincerely

Bin.

----- Original Message -----

*From:* David Sarrut <David.Sarrut at creatis.insa-lyon.fr>

*To:* 刘斌信件 <golder_time at 163.com>

*Cc:* gate-users <gate-users at lists.opengatecollaboration.org>

*Sent:* Wednesday, May 15, 2013 4:41 PM

*Subject:* Re: [Gate-users] how to set MU prescription dose lines

yes, but only 4 values [10;5], [5;0], [0;-5] and [-5;-10].

The SetPosition could be used to move the actor inside the attached volume
(waterbox in your case), in the coordinate system of the waterbox. So if
you set position to "0 0 5" for example, you will still have 4 dosels (dose
in volume) :  [15;10] [10;5], [5;0], and [0;-5]. But the first one is thus
outside the volume so no dose deposition will be stored in the first dosel.

Note that if you are saving the dose actor in mhd image file format, the
"origin" of the image is updated according this position.

David

On Wed, May 15, 2013 at 4:30 AM, 刘斌信件 <golder_time at 163.com> wrote:

Hi david ,

    What is the relationship between Doseactor and setPostion ,do the
"setPostion " set the origin of the scored dose voxel ? As the following is
an example,

/gate/world/daughters/name WaterBox

/gate/world/daughters/insert box

/gate/WaterBox/setMaterial Water

/gate/WaterBox/geometry/setXLength 20 mm

/gate/WaterBox/geometry/setYLength 20 mm

/gate/WaterBox/geometry/setZLength 20 mm

/gate/WaterBox/placement/setTranslation 0.0 0.0 0.0 mm

/gate/actor/addActor                   DoseActor dose

/gate/actor/dose/attachTo              WaterBox

/gate/actor/dose/setPosition           0 0 0 mm

/gate/actor/dose/setSize               5 5 20 mm

/gate/actor/dose/setVoxelSize          5 5 5 mm

as above , in my view , the actor will gets five dose points , their
z-axis coordinates are  10 ,5, 0, -5,-10, is that right? The "setpostion "
is used to set the symmetrical center of the volume of detected by
doseactor .

Thank you so much

Yours sincerely

Bin.

----- Original Message -----

*From:* David Sarrut <David.Sarrut at creatis.insa-lyon.fr>

*To:* 刘斌信件 <golder_time at 163.com>

*Sent:* Friday, May 10, 2013 6:58 PM

*Subject:* Re: [Gate-users] how to set MU prescription dose lines

this is classical "variance reduction technique" that consists in producing
n photons (instead of a single one), each of them with a relative weight of
1/n. It means that such photons behave like 1/n part of photon.

Look for articles/chapter on "variance reduction technique"

Sincerely,

David

On Fri, May 10, 2013 at 10:42 AM, 刘斌信件 <golder_time at 163.com> wrote:

Hi,

   I'm sorry that I  yet can't understand clearly  the "weight" and  "the
splitting factor n ", the following are the part of the text in the paper :

When a primary electron hit the target and produce a bremsstrahlung photon,
the SBS tool sampled n photons at once, with a weight of 1/n each, all
having the same energy and starting from the electron hit point in the
target, only the photon direction was sampled, according to the direction
criterion. User can define the splitting factor n, as well as the direction
criterion.

   What is  meaning of the setence "the SBS tool sampled n photons at once,
with a weight of 1/n each"? Thank you very much .

yours sincerely,

Bin

----- Original Message -----

*From:* David Sarrut <David.Sarrut at creatis.insa-lyon.fr>

*To:* 刘斌信件 <golder_time at 163.com>

*Cc:* gate-users <gate-users at lists.opengatecollaboration.org>

*Sent:* Friday, May 10, 2013 3:20 PM

*Subject:* Re: [Gate-users] how to set MU prescription dose lines

Hello,

there is no direct relationship between MU and number of primaries. You
need to somehow calibrate your system such as a given number of particles
gives you a given dose (ie 1 Gy at 10 cm in  water), and make the link with
the MU.

Yes the weight (1/N) of the particle is taken into account in the
doseactor. This is a weight associated with a particle (the E is not
divided, only the deposited E).

Sincerely,

David

On Thu, May 2, 2013 at 4:11 PM, 刘斌信件 <golder_time at 163.com> wrote:

hi,
  I  do not know the relation between "setTotalNumberOfPrimaries" of
simulation  and  MU prescription dose in the external radiotherapy . How
should  I set the number of the photon or events in simulation that the
absorbed depth dose in phantom will arrive at a expected value. In addition
, in Selective bremsstrahlung splitting (SBS) technology, the final state
of the process is generated N times and the weight of each secondary is
1/N. Does it divide the energy of photon ( original produced by the
bremsstrahlung)  into N pieces of energy ,and then get  single photon with
original  energy of 1/N in  the same direction ?
 Thank you for attention?
yours sincerely,
Bin
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-- 

David Sarrut, Phd
Chargé de recherche CNRS
CREATIS, UMR CNRS 5220, Inserm U 1044

Centre de lutte contre le cancer Léon Bérard
28 rue Laënnec, 69373 Lyon cedex 08
Tel : 04 78 78 51 51 / 06 74 72 05 42
http://www.creatis.insa-lyon.fr/~dsarrut
_________________________________

 "2 + 2 = 5,  for extremely large values of 2"
_________________________________

-- 

David Sarrut, Phd
Chargé de recherche CNRS
CREATIS, UMR CNRS 5220, Inserm U 1044

Centre de lutte contre le cancer Léon Bérard
28 rue Laënnec, 69373 Lyon cedex 08
Tel : 04 78 78 51 51 / 06 74 72 05 42
http://www.creatis.insa-lyon.fr/~dsarrut
_________________________________

 "2 + 2 = 5,  for extremely large values of 2"
_________________________________

-- 

David Sarrut, Phd
Chargé de recherche CNRS
CREATIS, UMR CNRS 5220, Inserm U 1044

Centre de lutte contre le cancer Léon Bérard
28 rue Laënnec, 69373 Lyon cedex 08
Tel : 04 78 78 51 51 / 06 74 72 05 42
http://www.creatis.insa-lyon.fr/~dsarrut
_________________________________

 "2 + 2 = 5,  for extremely large values of 2"
_________________________________

-- 

David Sarrut, Phd
Chargé de recherche CNRS
CREATIS, UMR CNRS 5220, Inserm U 1044

Centre de lutte contre le cancer Léon Bérard
28 rue Laënnec, 69373 Lyon cedex 08
Tel : 04 78 78 51 51 / 06 74 72 05 42
http://www.creatis.insa-lyon.fr/~dsarrut
_________________________________

 "2 + 2 = 5,  for extremely large values of 2"
_________________________________
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