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Radiotherapy treatment planning with dynamic wedges--an algorithm for generating wedge factors and beam data
1Medical Physics Department, Addenbrooke's Hospital, Cambridge, UK.
Physics in Medicine and Biology
|September 1, 1995
Summary
Computer-controlled linear accelerator jaws create dynamic wedges, mimicking traditional wedge filters. A new algorithm accurately predicts dose distributions for these dynamic wedges, enabling faster treatment planning.
Area of Science:
- Medical Physics
- Radiation Oncology
- Radiotherapy Technology
Background:
- Traditional wedge filters in linear accelerators create sloped dose distributions, essential for conformal radiotherapy.
- Implementing dynamic wedges using computer-controlled jaw movements offers potential advantages in treatment planning and delivery.
Purpose of the Study:
- To develop and validate an algorithm for calculating dose distributions of dynamic wedges generated by Varian linear accelerators.
- To model dynamic wedged beams as a superposition of static asymmetric beams.
Main Methods:
- Utilized segmented treatment tables (STTs) from Varian linear accelerators.
- Developed an algorithm based on measured data from symmetric beams to model asymmetric beams.
- Calculated dose per monitor unit at any point in the beam using STT values.
Main Results:
- The algorithm accurately predicted wedge factors, depth doses, and beam profiles for dynamic wedges.
- Predictions showed good agreement with experimental measurements.
- The algorithm demonstrated efficient computation, with a typical calculation time of 5 ms/dose point on a 486DX PC.
Conclusions:
- The described algorithm provides an accurate and efficient method for calculating dose distributions for dynamic wedges.
- This method facilitates the use of dynamic wedges in radiotherapy, potentially improving treatment planning and delivery.
- The computational efficiency suggests practical applicability in clinical settings.