Evaluation of RayStation robust optimisation for superficial target coverage with setup variation in breast IMRT

Area of Science:

• Radiation Oncology
• Medical Physics
• Radiotherapy Planning

Background:

• Breast Intensity-Modulated Radiation Therapy (IMRT) planning faces challenges ensuring adequate CTV coverage due to proximity to the patient's surface.
• Setup variations can compromise dose delivery accuracy, necessitating robust planning strategies.

Purpose of the Study:

• To evaluate the efficacy of robust optimization in maintaining target dose coverage for breast IMRT under setup uncertainties.
• To compare robust optimization with other planning techniques for breast cancer radiotherapy.

Main Methods:

• Generated breast IMRT plans using opposed tangential beams and robust optimization.
• Delivered and computed plans at 5 mm and 10 mm offsets perpendicular to beam axes.
• Verified dose computation accuracy and evaluated surface dose coverage at offset positions.

Main Results:

• Robust optimization with a 10 mm margin ensured CTV minimum, maximum, and mean doses within 3% at 5 mm and 10 mm offsets compared to no offset.
• Dose computation accuracy was verified using scintillator and film measurements.
• Surface dose coverage was maintained across offset positions with robust optimization.

Conclusions:

• Robust optimization is a viable and effective technique for ensuring breast CTV coverage in IMRT despite setup variations.
• The performance of robust optimization is comparable to established methods for managing setup uncertainties in breast radiotherapy.