[Gate-users] PencilBeam source for Gamma Camera validation

[Matthew Strugari]

Hi Khalid,

It may take a few times reading through the standard to fully understand the procedure. It is a dense and very detailed document which fully describes the setup, measurement, and calculation.

Typically, the intrinsic resolution setup places a point source of Tc-99m at a distance greater than 5x the useful field of view (UFOV) from the detector face. The detector face is covered with a 3 mm thick lead mask containing 1 mm wide parallel slits extending across the UFOV and spaced 30 mm apart. When irradiated, the mask creates the line profiles which can be analyzed according to the NEMA procedure (NOT a Gaussian fit).

The NEMA standards provide a comparable measure between different imaging systems which makes it useful in validating Monte Carlo simulations. If you are using these standards, you will want to model your simulation as described and as achievable with your physical setup. This would not require a collimated line source. If you are not following the standard, then you can disregard the above and use a collimated line source to obtain a general measurement of the resolution from a point spread function.

Cheers,
Matthew

On May 16, 2020, at 10:29 AM, Khalid Hussain <khalidhussain1134 at gmail.com> wrote:


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Dear Matthew,

Thank you so much for your reply.

I am interested in a source that can help to calculate intrinsic spatial resolution of the camera not in pencilBeam. I read the NEMA standard where line source with parallel lead strips are used to measure the intrinsic spatial resolution. Here is the screenshot of that page;
<image.png>


I am not clear about this procedure of measurement, either lead strips with line source are used for hardware validation only or it can be used for software simulation ?

I am not interested in PencilBeam source, I only want the correct one which can be used for  SPECT gamma camera validation.

Should I also use these lead strips along with line source, please guide, I am validating camera first time that is why I am facing difficulty in selecting proper source etc.

Thanking you


Regards
Khalid Hussain
PhD Student, UPM


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On Sat, May 16, 2020 at 6:10 PM Matthew Strugari <matthew.strugari at dal.ca<mailto:matthew.strugari at dal.ca>> wrote:
Hi Khalid,

I’m not too experienced with the pencil beam source, but is there any particular reason you’d like to use the pencil beam source vs a collimated line source? I believe the pencil beam is intended for beam lines produced by a linear accelerator. Obviously you can use it however you desire, but using a pencil beam would not simulate blurring from the source distribution and therefore would not aid in fully validating intrinsic spatial resolution. Have you looked into the NEMA standards for characterizing intrinsic spatial resolution on gamma cameras?

Positively,
Matthew

On May 16, 2020, at 7:14 AM, Khalid Hussain <khalidhussain1134 at gmail.com<mailto:khalidhussain1134 at gmail.com>> wrote:


CAUTION: The Sender of this email is not from within Dalhousie.
Dear Gate Users and Experts,

I want to validate the Gamma camera intrinsic spatial resolution for which you know PencilBeam <https://opengate.readthedocs.io/en/latest/source_and_particle_management.html#pencil-beam-source> source is required.

I am using the below scripts for this source which seems to be inaccurate, please have a look on this script and guide me.

/gate/source/addSource gps PencilBeam
#/gate/source/gps/type PencilBeam
/gate/source/gps/setParticleType gamma
/gate/source/gps/setPosition 0 0 0 mm
/gate/source/gps/setEnergy  140.0 keV
/gate/source/gps/setActivity 3.7 MBq
/gate/source/gps/setSigmaX 2 mm
/gate/source/gps/setSigmaY 2 mm
/gate/source/gps/setSigmaTheta 3.3 mrad
/gate/source/gps/setSigmaPhi 3.8 mrad
/gate/source/gps/setEllipseXThetaEmittance 15 mm*mrad
/gate/source/gps/setEllipseXThetaRotationNorm negative
/gate/source/gps/setEllipseYPhiEmittance 20 mm*mrad
/gate/source/gps/setEllipseYPhiRotationNorm negative


Regards
Khalid Hussain
PhD Student, UPM

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