G4Linacs

Simulations of linear accelerators (Linacs) and clinical heads in Geant4.

Description

G4Linacs is a collection of scenarios and configurations for simulating radiation sources and medical linear-accelerator heads using Geant4. The goal is to provide reusable models (e.g., Halcyon6MV, Infinity6MV, Infinity6MV_PSF) that allow dose-distribution studies, detector-response profiling, and the generation of phase-space files (PSF) and other parameters relevant to medical physics.

Each subfolder contains a variant of the model (source code, CMake build files, macros, and output data) designed for different linacs or simulation configurations.

Repository Structure

• Halcyon6MV/ — Halcyon 6 MV model

• Infinity6MV/ — Infinity 6 MV model

• Infinity6MV_PSF/ — Variant for PSF generation

• Each folder contains:

  • CMakeLists.txt — build file
  • src/ — C++ source (DetectorConstruction, PrimaryGenerator, PhysicsList, etc.)
  • include/ — headers
  • macros/ — example macros to run simulations
  • build/ — project and compilation outputs (should not be versioned if using .gitignore)
  • data.ipynb, merged_output.csv — example notebooks and data

Requirements

• Geant4 (compatible version; 10.x or newer recommended)
• CMake
• Modern C++ compiler (MSVC, GCC, or Clang)
• Python (optional, for notebooks and analysis)

Build (Windows)

Open the Developer Command Prompt for Visual Studio, create a build directory inside the project folder, and run:

cd Halcyon6MV    # or the desired subproject
mkdir build; cd build
cmake ..
cmake --build . --config Release

To select a specific generator or Visual Studio version, use cmake .. -G "Visual Studio 16 2019" -A x64 instead of plain cmake ...

On Linux or macOS, use the system generator and a standard terminal (e.g., cmake .. && make).

Run

After building, run the simulation executable with:

sim --t <num_threads> --s <seed> [macro_filename]

• --t <num_threads>: number of threads. If omitted, all CPU cores are used.
• --s <seed>: random seed. If omitted, a random seed is selected.
• [macro_filename]: path to a Geant4 macro file (e.g., macros/default.mac). If omitted, the default macro is used.

Examples:

.\sim.exe --t 8 --s 12345 macros\default.mac
.\sim.exe                 # runs with default macro, random seed, all threads

Notebooks (data.ipynb) are provided for post-processing and output analysis.

Best Practices

• Do not version the build/ folder (add an entry in .gitignore).
• Keep detector code (DetectorConstruction) and physics list (PhysicsList) separated to simplify testing.
• Specify units explicitly (cm, mm, m, etc.) when defining dimensions.

Contributions

To contribute:

• Open an issue describing the improvement or bug.
• Create a branch for your work.
• Submit a pull request with tests or usage examples.

License

Add your preferred license here (MIT, Apache-2.0, etc.) or leave it under your group/institution policy.

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If you want, I can:

• Add a recommended .gitignore for Geant4/CMake projects on Windows.
• Generate a basic CONTRIBUTING.md.
• Format the README.md files inside each subfolder with model-specific instructions.