Introducing interactive inverse FEM simulation and its application for adaptive radiotherapy

Area of Science:

• Medical imaging
• Computational mechanics
• Radiotherapy physics

Background:

• Radiotherapy for head and neck cancer can alter parotid gland shape and position.
• These anatomical changes may lead to parotid glands intersecting the target radiation volume.
• Accurate registration of anatomical structures is crucial for adaptive radiotherapy planning.

Purpose of the Study:

• To develop a semi-automatic deformable registration methodology for anatomical structures.
• To enable real-time adaptation of radiotherapy plans based on patient anatomical changes.
• To improve the precision of radiation delivery and minimize dose to organs at risk, like parotid glands.

Main Methods:

• Interactive inverse simulations utilizing non-linear real-time Finite Element Method (FEM).
• A constraint-based framework with user-provided registered points for optimization.
• Model projection into a reduced space for rapid quadratic programming problem solving.

Main Results:

• Validated numerical examples for retrieving material properties and boundary conditions.
• Demonstrated successful registration of parotid glands in head and neck cancer radiotherapy.
• Showcased the potential for adapting radiotherapy planning to limit radiation dose to parotid glands.

Conclusions:

• The proposed methodology offers an efficient and accurate approach for semi-automatic deformable registration.
• This technique can significantly aid in adaptive radiotherapy by accounting for anatomical variations.
• The method has direct clinical implications for optimizing radiation therapy for head and neck cancer patients.