X-ray fluorescence data repository

Use data simulation tools from Geant4 to generate reasonable XRF data.

SIMULATION DESCRIPTION

X-ray fluorescence (XRF) imaging simulation using a pencil beam of monochromatic photons incident on a breast tissue target.

• The target is modeled as soft tissue containing 2% (weight fraction) gold.
• Fluorescence photons are generated in the target, mainly from the Au K lines (~67, 69, 77, 78 keV) and some L lines (~9, 11, 13 keV).
• The background signal originates from Compton-scattered primary photons.
• Both the target and the detector volumes are defined as sensitive detectors (SD) in Geant4.
• In the target SD, fluorescence creation events are recorded.
• In the detector SD (a simplified pure silicon detector), all photon interactions are recorded.

The aim of the simulation is to distinguish between signal events (fluorescence photons depositing their full energy in the detector) and background events (primarily Compton-scattered photons).

SIMULATION CODE

Genat4 toolkit is used for the simulation.
Link to GitLab repository.

• original code by Kunal Kumar (master branch)
• adjusted and developing code - joint work of Andrej Studen and Matevž Hudovernik (xrf branch)

SIMULATION SETUP

Here, simulation setup and geometry description will follow.

PRESENTATION

link to presentation
...

DATA FORMAT: DetHits.txt

This files contain the list of detector interaction events. Each line corresponds to one interaction step of a photon in the detector.

The columns are:

• photon_id – unique index of each photon entering the detector (0, 1, 2, …). If a photon undergoes multiple interactions, the same photon_id appears on several lines.
• E0 – initial photon energy:
  • For primaries: beam energy.
  • For fluorescence photons: energy at creation (line energy).
• Eentry – photon energy when entering the detector.
• fluo_photon – Boolean flag: 1 if photon is fluorescence, 0 if background (non-fluorescence).
• xint, yint, zint – coordinates of the interaction location in the detector volume.
• voxel_id (VID) – voxel index of the interaction, using row-major ordering.
• Edep_step – energy deposited in this interaction step.

Thus, one photon can correspond to multiple rows in the file if it undergoes multiple interactions before stopping or escaping.

DATA PROCESSING

For processing of raw output simulation data, code found on this GitHub repository is used [currently private, needs update to useful format].