Poster - Thurs Eve-19: IGRT QA for helical tomotherapy

Area of Science:

• Medical Physics
• Radiotherapy Technology
• Radiation Oncology

Background:

• Helical tomotherapy (HT) utilizes daily imaging with mega-voltage computed tomography for 3D image-guided radiotherapy (IGRT).
• Ensuring the accuracy and reliability of the IGRT process is crucial for effective patient treatment.
• Verification of the HT IGRT system's integrity is essential for safe and precise radiation delivery.

Purpose of the Study:

• To present two novel techniques for verifying the integrity of the helical tomotherapy image-guided radiotherapy process.
• To validate the accuracy of image registration and the overall IGRT procedure in a clinical setting.
• To establish robust quality assurance (QA) protocols for HT IGRT systems.

Main Methods:

• Development of a polystyrene phantom with ionization chamber and radiochromic film inserts for dose verification.
• Implementation of daily QA procedures to test image registration accuracy using phantom positioning and known displacements.
• Creation of a comprehensive QA plan within the treatment planning system (TPS) to verify the entire IGRT process, including dose delivery comparison.

Main Results:

• The developed phantom and QA procedures successfully verified the image registration accuracy of the HT IGRT system.
• The second procedure effectively validated the entire IGRT process, including dose delivery accuracy.
• Ion chamber measurements and film dosimetry results correlated well with the planned dose distribution.

Conclusions:

• The presented QA techniques adequately test the image-guided radiotherapy capabilities of helical tomotherapy units.
• These methods provide a reliable means to ensure the integrity of daily IGRT procedures.
• Implementation of these QA protocols enhances the safety and precision of radiotherapy treatments delivered with HT.