[Gate-users] Dose ditribution map when a point source moves along a human GI tract

[Simon Stute]

Hi Tony,

This is not a simple thing that you want to do.

I would recommend to separate the problem of finding the intestine from the
Gate simulations.
Start by writing a program to compute the intestine position for the source
as you want, for a given time.
Then I would suggest to perform one Gate simulation for each time position
of the source. Use the previously computed intestine source position to
automatically generate the source macro for the simulations with respect to
the chosen time slice. The rest of the macro should roughly stays the same
from a position to another (change the output name and time info by
automatic generation too).

I would do it that way if I had to do such an experiment. This is more
simple to not correlate the 2 problems and this allows you to have more
flexibilty to debug your simulations compared to using the GenericMove in
one simulation.
At the end, just sum your dose maps.

Regards,
Simon


On Wed, Mar 12, 2014 at 7:42 AM, Tony <tucadaica at yahoo.com> wrote:

> Could anybody please help with the above questions? Or is it possible to
> determine the position of the center of the cross section of the intestine
> at each slice/voxel, so that I can use the "Generic Move" in GATE to move
> the source in each time slice.
>
> Thank you in advance.
>
>
>   On Monday, 10 March 2014 6:02 PM, Tony <tucadaica at yahoo.com> wrote:
>   Hi GATE users,
>
> I am trying to figure out if it would be possible to obtain a 3D dose
> distribution map in a GATE simulation, in which a point source (geometric
> source:  1mm-diameter sphere) moves along a human gastro-intestinal
> tract.
>
> I have read the GATE user guide carefully, especially the section about
> voxelized phantom and dose collection. However, since I am quite new to the
> field of medical physics, there were many parts I could not understand
> clearly.
>
> As far as I know, I would need to use a voxelized phantom, such as the
> "Extended 4D NCAT Phantom" in which the gastro-intestinal tract is also
> included. Then, a 1mm-diameter sphere source needs to be defined and it
> should be able to move along the intestine.
>
> I have successfully run several GATE simulations in which a geometric
> source moves in a basic trajectory inside a geometric phantom, but I have
> never worked with a voxelized phantom and a complex movement of the source
> before.
>
> My questions are:
> 1) Would it be possible to produce such a 3D dose distribution map in GATE
> when a 1mm-diameter spherical source moves along the intestinal tract
> (assuming the source has a constant speed, approximately 8 hours to
> complete its journey, similar to food excretion)?
>
> 2) Assume that I already got the Extended 4D NCAT Phantom, how can I
> define the source movement so that the source can move along the intestine
> of the phantom?
>
> 3) Does the 3D dose distribution map show the total absorbed dosedeposited in every voxel of the NCAT phantom throughout 8 hour moving of
> the source?
>
> Your help would be greatly appreciated.
> Thank you,
>
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