Implementation of enhanced dynamic wedge in the focus rtp system.

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Systems

Background:

• Accurate dose calculation is critical for effective radiation therapy.
• Varian's enhanced dynamic wedge (EDW) requires precise modeling for dose distribution and wedge factor (WF) calculations.
• Existing methods using segmented treatment tables (STTs) can have significant errors, particularly for large fields.

Purpose of the Study:

• To present the FOCUS RTP system implementation for Varian's EDW.
• To introduce a novel method for calculating dose distributions and WFs with improved accuracy.
• To reduce discrepancies in dose calculations compared to the standard MU fraction model.

Main Methods:

• Utilized segmented treatment tables (STTs) to derive a transmission matrix for dose calculation.
• Employed Clarkson or convolution/superposition algorithms for dose computation.
• Incorporated a scatter dose correction using measured WFs and interpolation for improved accuracy.

Main Results:

• Achieved good agreement (within 3% or 3 mm) for dose distributions with measured data for 6-MV beams.
• Obtained excellent agreement (within 1%) for WFs in symmetric and asymmetric fields for 6- and 10-MV beams.
• Demonstrated significant improvement over the MU fraction model for large wedge angles and field sizes.

Conclusions:

• The presented FOCUS RTP system with scatter dose correction enhances the accuracy of EDW dose calculations.
• This method offers a substantial improvement over traditional models, leading to more reliable radiotherapy treatments.
• The findings support the clinical implementation of this refined dosimetry approach for Varian's EDW system.