Appropriate EGSnrc user codes for simulating an x-ray radiography experiment

[walleludvig]

Hi EGSnrc community.

I seek suggestions for appropriate EGSnrc user codes to implement a particular in-silico experiment. I wish to simulate a typical radiography setup, in-which a x-ray beam passes through an anthropomorphic phantom and deposits its energy to a flat panel detector some distance behind the phantom. I have already generated the x-ray spectra using BEAMnrc and scored a phasespace file at the exit of the collimators. Now I wish to use these spectra as the source in other simulations, where the photons traverses the phantom before depositing their energy in a flat panel detector. I have modelled the flat panel detector in a pixelated fashion using egs_ndgeometry of the type EGS_XYZGeometry and stored it in a .geom file. A voxelized model of the phantom has also been created using ctcreate and exists as an .egsphant file.

I believe DOSXYZnrc could be suitable for my application, however I have been unable to sucessfully include both the phantom and the detector geometries in the same input file, and somewhat unsure if this is even doable.

I have constructed my experimental setup using the typical syntax of egs++ input files but not sure that any of the egs++ applications would be appropriate to achieve a simulation projection images which is what I want. Here is an image of my geometry setup in egs_view: (note: surrounding box (red) is just the surrounding air region)

I seek advice on which user code in EGSnrc could be suitable to achieve my desired outcome. To be clear I do not wish to score dose depositions in the phantom itself but wish to simulate generation of projection images in the flat panel detector (e.g., as dose scored in each of the pixel voxels of my detector geometry).

Any advice, ideas or suggestions are greatly appreciated!

[rtownson]

DOSXYZnrc can only handle a single egsphant file as input, so egs++ is the better choice. You can score the dose to each voxel in your flat panel using egs_dose_scoring. It will print the dose to each region in a range, which you can determine using egs_view. You'll just have the process the region numbers into the voxel location, but this should be reasonable straightforward.

https://nrc-cnrc.github.io/EGSnrc/doc/pirs898/classEGS__DoseScoring.html

E.g. use dose start region and dose stop region to list the range of regions for the voxels, and the dose to those regions will be output at the end of the simulation.

By the way, you could consider looking at the functionality of egs_cbct, it has some powerful VRTs implemented for kV imaging.

[walleludvig]

Hi @rtownson,

Thank you very much for the helpful information! I will first attempt to go with the egs_dose_scoring as suggested (I believe this can be implemented with a simple application similar to tutor2pp, correct?) and then I will also look more into egs_cbct. As I already have the experimental setup in egs++ input file format I expect this to be reasonably doable so great news!

Thanks again!