An efficient procedure for tomotherapy treatment plan verification using the on-board detector.

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Technology

Background:

• Accurate verification of radiation therapy treatment plans is crucial for patient safety.
• Tomotherapy requires robust methods for plan verification, especially with advanced features like dynamic jaws (TomoEDGE).

Purpose of the Study:

• To develop and validate a fast and simple procedure for tomotherapy treatment plan verification using the on-board detector (OBD).
• To enable verification of plans with both static and dynamic jaws (TomoEDGE).

Main Methods:

• A convolution-based calculation model was developed to correlate treatment planning system leaf control sinograms with on-board detector (OBD) data.
• The convolution kernel was optimized using the Tomotherapy Cheese phantom and found to be a Lorentzian function with specific parameters for different jaw openings.
• Plan verification utilized a gamma-index analysis with dose and distance-to-agreement criteria (3% / 2 mm).

Main Results:

• The developed procedure was applied to approximately 50 clinical treatment plans previously validated with the Delta4 phantom.
• 96% of the tested plans successfully passed the verification criteria.
• The method demonstrated higher sensitivity than the Delta4 phantom, identifying potential discrepancies in leaf open time for 4% of plans.

Conclusions:

• The developed on-board detector (OBD) procedure provides a fast, simple, and effective method for tomotherapy plan verification.
• This technique enhances the monitoring of treatment delivery accuracy and offers advantages over existing phantom-based methods.
• The procedure is suitable for verifying plans with static and dynamic jaws (TomoEDGE).