Rational for this Research

• Simulation of X-Ray attenuation extensively studied in physics;
• Different physically-based simulation code available;
• Physically-based simulation usually performed using Monte Carlo methods on CPU (often used in dosimetry for radiotherapy);
  • Very accurate; but
  • Computing an image requires a very very very long time (e.g. days or weeks);
• Ray-tracing is an alternative, but
  • Still relatively slow on CPU;
  • Does not easily take into account scattering;
    • Scattering does not necessarily matter in X-ray transmission imaging;
  • Does not include Poisson counting noise;
    • Poisson noise can be added as a post-process.

Medical Training using VR

• PhD (start 2003) and Postdoc (start 2006) in medical VR;
• Development of VR apps to train Interventional radiologists;
  • Stick needles and catheters in the human body whilst looking at images
  • Such as fluoroscopy;
  • Real-time X-ray images on a TV screen.
• Not interested in scattering;
• Noise is not an issue;
• Ray-tracing is viable in this context.

Need for a Simulation Library that is

• Open-source (with a flexible license)
  • Can be used in open-source projects
  • Can be used in closed source commercial applications too
• Fast
  • GPU implementation.
• Flexible
  • Available for most popular programming languages
• Cross platform
  • Run on GNU/Linux, Mac OS X and Windows
• Validated

In a nutshell, gVirtualXray is

• a C++ X-Ray simulation library
• Open source;
• Realtime;
• Portable;
• Validated;
• Available for many programming languages.

Fact sheet

• SVN repository hosted by
• Implemented in using
• Cross-platform, the library works on
  • Windows, GNU/Linux, and Mac OS X,
  • Nvidia and AMD graphics cards,
  • Integrated GPUs,
  • Desktop PCs and Laptops.
• Is accurate (quantitative validation);
• Enable reproducible research;
• Supports : Photon Cross Sections Database from ;
• Uses polygon meshes to model 3-D geometries from popular file formats (eg. STL, PLY, 3DS, OBJ, DXF, X3D, DAE)

Example of wireframe model

Simulation supports:

• Various source shapes
  • Point source;
  • Cube source;
  • Parallel beam.
• Incident beams:
  • Monochromatic;
  • Polychromatic.
• Geometries:
  • Surface meshes (triangles);
  • Volume meshes (tetrahedrons). NEW
• Material properties:
  • Chemical elements (e.g. W for tungsten);
  • Compounds (e.g. H2O for water); NEW
  • Mixture (e.g. Ti90/Al6/V4); NEW
  • Hounsfield units (for medical applications).

More recently

• Improved installation from source code.
• Converter from Abaqus files 2 STL files: NEW
  • The simulation works with volumetric meshes (tetrahedrons),
  • With surface meshes (triangles)
• Always working on improvements (when time allows)
  • Currently working on the deployment on SuperComputing Wales. work-in-progress
  • Port to Vulkan? work-in-progress
  • Maybe one day, a Matlab wrapper?

Applications of gVirtualXRay

• Teaching particle physics to undergraduates;
• Virtual Reality Simulation;
• Virtual Testing Lab
• Design new clinical imaging modality to reduce dose exposure
• Teaching radiography in medicine

GUI of radiography tool

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