How to fano test your egs++ simulation

[rtownson]

Instructions for performing the Fano Test

Overview

There are two applications for the Fano test: egs_volume and egs_fano. Follow the steps below to set them up and run the fano test. You don't need the egs_volume Monte Carlo tool if you know your region volumes or can calculate them easily.

Please note that these applications are rudimentary, for example you need to recompile (make) the fano test application when you change the size of the fano box.

Please let me know if these instructions are unclear, incomplete or incorrect!

egs_volume

Download egs_volume.zip

Steps

1. Build program

   • In egs_volume/Makefile, replace the 3 occurrences of a6fc389 with the name of your .conf file (without the .conf extension), which is generated when you configured EGSnrc, and is located in $HEN_HOUSE/specs.

2. Run example

   • Execute the following command:

     cd $EGS_HOME/egs_volume/
     make
     ./egs_volume volume_example.egsinp

3. For your own files

   • Place your files in the egs_volume/ directory

   • Add a block in "scoring options" similar to the one in the example.

Notes

• Passes: Represents the depth of the generated octree. More passes require significantly more memory.

• Samples: Number of randomly sampled points per pass. Computation time is linear with samples.

• Bounding box: Adjust box min and box max to contain your geometry.

• Labels: Optionally, define labels in your geometry to get combined volumes of several regions.

egs_fano

Download egs_fano.zip

Steps:

1. Run Example:

   • Execute the following command:

     cd $EGS_HOME/egs_fano/
     make
     ./egs_fano -i fano-example.egsinp

2. Modify for Your Use:

   • Specify the Fano box in egs_fano.cpp and run make after each change.
   • Define a strictly enclosing box in your geometry that corresponds to region 0 (using an existing geometry is fine)
   • Define the Fano source with the same box dimensions.
   • Ensure the same material is used everywhere, but with actual bulk densities.
   • Include an ausgab object to calculate the dose in each region.
   • Specify known volumes of dose regions, or compute them using data from egs_volume.

Additional Tips:

• Ensure all regions have the same material but different densities.

• One option is to duplicate one density correction file and update the bulk density in the header for each Fano material.

• Don't specify materials inline in the input file, without a density correction file, because EGSnrc then calculates density corrections using a legacy Peirls model, which then vary according to the material specified.