Pre-treatment radiotherapy dose verification using Monte Carlo doselet modulation in a spherical phantom
Reid W Townson1, Sergei Zavgorodni
1Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia, Canada. Department of Medical Physics, BC Cancer Agency, Vancouver Island Centre, Victoria, British Columbia, Canada.
Physics in Medicine and Biology
|March 22, 2014
Summary
A new spherical doselet modulation (SDM) method enables rapid, accurate 3D dose reconstruction for radiotherapy. This technique significantly reduces calculation time and uncertainty in dose verification for complex treatments.
Area of Science:
- Medical Physics
- Radiation Oncology
- Computational Dosimetry
Background:
- Accurate radiotherapy dose verification is crucial due to increasingly complex treatment delivery.
- Pre-treatment verification is essential for ensuring patient safety and treatment efficacy.
Purpose of the Study:
- To develop a rapid pre-treatment verification technique for reconstructing 3D dose distributions.
- To enable reconstruction for both coplanar and non-coplanar radiotherapy treatments.
Main Methods:
- Developed the spherical doselet modulation (SDM) method using pre-calculated Monte Carlo (MC) doselets.
- Utilized electronic portal images to derive delivered fluence maps.
- Reconstructed dose in a spherical water phantom by modulating and summing MC doselets, exploiting azimuthal symmetry.
Main Results:
- The SDM method reduced the number of doselets needed by approximately 250-fold.
- Achieved high accuracy with mean chi- and gamma-test (3%/3 mm) success rates of 98.6% and 99.5% compared to full MC simulations.
- Demonstrated a total calculation time of 96 seconds per treatment field on a single processor core.
Conclusions:
- The SDM method offers a fast and accurate approach for pre-treatment dose verification in radiotherapy.
- This technique effectively mitigates statistical uncertainty and computational intensity in dose reconstruction.
- The SDM method is suitable for complex radiotherapy delivery, including IMRT and non-coplanar treatments.
