SU-F-BRCD-06: Multiple Anatomy Optimization of Accumulated Dose

Area of Science:

• Radiation Oncology
• Medical Physics
• Computational Biology

Background:

• Radiotherapy planning often uses a single image, which can lead to inaccuracies for moving targets.
• Deformable image registration and dose accumulation are crucial for accurate radiotherapy in moving anatomy.
• Internal Target Volume (ITV) methods may not fully capture dose delivered to a moving Clinical Target Volume (CTV).

Purpose of the Study:

• To implement and evaluate Multiple Anatomy Optimization (MAO) using deformable dose accumulation on 4D CT datasets.
• To compare MAO with the ITV envelope method for lung cancer radiotherapy.
• To assess the impact of MAO on target dose coverage and organ-at-risk sparing.

Main Methods:

• Six lung cancer patients underwent radiotherapy planning using both ITV and MAO methods.
• MAO optimized a single plan for all 10 breathing phases, ensuring accumulated dose objectives were met.
• Plans were compared based on accumulated dose, with target dose constrained to 70 Gy.

Main Results:

• MAO improved target V70 coverage by an average of 2.8% and reduced ipsilateral lung V20 by up to 3% in five of six cases.
• MAO also reduced contralateral lung V20, esophagus V25, and heart V30 by up to 5%, 3%, and 3%, respectively.
• In one case with minimal tumor motion, MAO did not offer significant improvement over the ITV plan.

Conclusions:

• Dose-volume optimization on a single static image is insufficient for ensuring adequate dose coverage to moving targets.
• Multiple Anatomy Optimization effectively addresses dose ambiguity and enhances the quality of radiotherapy plans for moving targets.
• MAO represents a significant advancement in personalized radiotherapy for thoracic malignancies.