On-Board Imager-based MammoSite treatment verification

Area of Science:

• Radiation Oncology
• Medical Physics
• Brachytherapy

Background:

• Conventional simulators are increasingly absent in radiation oncology departments.
• Image-guided radiation therapy and virtual simulation are becoming standard practices.
• There is a need for efficient and precise verification methods in MammoSite brachytherapy.

Purpose of the Study:

• To develop and evaluate a CT-based protocol for MammoSite brachytherapy using an On-Board Imager (OBI) for daily verification.
• To assess the feasibility and accuracy of OBI-based simulation for MammoSite procedures.
• To establish a rapid, filmless verification process as an alternative to conventional simulators.

Main Methods:

• A protocol utilizing CT-based planning, a Source Position Simulator (SPS) with a Simulator Wire, and an OBI was developed.
• MammoSite balloon implantation was followed by CT imaging for evaluation.
• OBI fluoroscopy was used for daily verification of balloon integrity and dwell position coincidence.

Main Results:

• The OBI-based verification process is filmless, rapid (under 10 min), and precise.
• Balloon diameter correlated well (within 1 mm) between CT and OBI images.
• Balloon symmetry was accurately defined (1 mm accuracy) using OBI console tools.

Conclusions:

• OBI-based simulation is a feasible and effective alternative for MammoSite balloon evaluation and daily verification.
• The developed protocol ensures precision without undermining accuracy.
• This method streamlines the verification process, replacing the need for conventional simulators.