A kernel-based dose calculation algorithm for kV photon beams with explicit handling of energy and material...

Area of Science:

• Medical Physics
• Radiation Oncology
• Small Animal Research

Background:

• Advancing radiobiology requires precise radiotherapy mimicking clinical techniques for small animal models.
• Intensity-modulated radiotherapy (IMRT)-like schemes are being developed for small animal irradiators.
• Accurate dose calculation is crucial for small animal radiotherapy research.

Purpose of the Study:

• To develop and validate a fast analytical dose calculation algorithm for keV photon beams in small animal radiotherapy.
• To implement IMRT-like irradiation schemes for small animals.
• To provide a computationally efficient alternative to Monte Carlo simulations.

Main Methods:

• A superposition-convolution approach adapted for kV X-rays, assuming local energy deposition.
• Separation of dose calculation into primary dose and scatter contribution using a point kernel method.
• Validation against Geant4 Monte Carlo simulations and Muriplan software.

Main Results:

• The algorithm achieved a mean disagreement of 1.7% with Monte Carlo simulations for water phantom depths.
• Deviations were up to 4% in the entrance region and 5% at 7 cm depth.
• Calculation time was approximately 5 seconds per beam, with larger discrepancies at material interfaces.

Conclusions:

• The fast analytical algorithm shows good agreement with Monte Carlo simulations for kV photon beams.
• It offers a potential alternative to computationally intensive Monte Carlo methods for small animal radiotherapy.
• The algorithm is valuable for IMRT and inverse planning in high-precision small animal studies.