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Monte Carlo modelling of a virtual wedge
1Physics Department, Royal Marsden Hospital (Institute of Cancer Research), London, UK. f.verhaegen@icr.ac.uk
Physics in Medicine and Biology
|January 1, 2000
Summary
Virtual wedges, created by moving collimator jaws, offer flexible arbitrary wedge angles without altering photon beam quality. Unlike physical wedges, virtual wedges do not cause beam hardening or dose uniformity issues, making them a superior alternative in radiation therapy.
Area of Science:
- Medical Physics
- Radiation Oncology
- Radiotherapy Physics
Background:
- Physical photon wedges are traditionally used in radiotherapy for dose shaping.
- These wedges can cause beam hardening and reduce dose uniformity.
- Virtual wedges offer a flexible alternative with arbitrary wedge angles.
Purpose of the Study:
- To investigate the impact of a virtual wedge on photon beam spectra.
- To compare the beam quality of virtual wedges versus physical wedges.
- To validate simulation accuracy with experimental data.
Main Methods:
- Utilized the Monte Carlo code EGS4/BEAM for simulation.
- Modeled a Siemens MD2 accelerator (6-10 MV).
- Compared calculated dose profiles with experimental measurements.
Main Results:
- Monte Carlo simulations showed good agreement with measured dose profiles.
- Virtual wedges demonstrated an insignificant effect on beam quality.
- Physical wedges were confirmed to introduce significant beam hardening.
Conclusions:
- Virtual wedges are a viable alternative to physical wedges in radiotherapy.
- Virtual wedges do not negatively impact beam quality.
- This study validates the use of Monte Carlo simulations for assessing radiotherapy beam modifiers.