Functional avoidance-based intensity modulated proton therapy with 4DCT derived ventilation imaging for lung cancer

Area of Science:

• Radiation Oncology
• Medical Physics

Background:

• Intensity modulated proton therapy (IMPT) and volumetric modulated arc therapy (VMAT) are advanced radiation techniques.
• Functional avoidance-based planning utilizes 4D CT ventilation imaging to spare functional lung tissue.

Purpose of the Study:

• To evaluate dosimetric gains of functional avoidance-based proton therapy planning.
• To compare functional IMPT plans with standard IMPT and VMAT plans.
• To assess the impact of proton motion interplay effects.

Main Methods:

• 31 patients' 4DCT data were used for IMPT and VMAT planning.
• Dosimetric parameters were compared using ANOVA and t-tests.
• Normal Tissue Complication Probability (NTCP) models estimated toxicity risks.

Main Results:

• Functional IMPT significantly reduced dose to functional lung structures compared to functional VMAT.
• No significant dose degradation was observed for OARs or CTV with functional IMPT, even with interplay effects.
• A mean 5.7% reduction in Grade 2+ radiation pneumonitis was observed with functional IMPT versus standard IMPT.

Conclusions:

• Functional IMPT effectively spares healthy lung tissue and reduces dose to normal structures.
• NTCP calculations indicate a reduced risk of pulmonary complications with functional IMPT.
• Proton therapy planning can be optimized using functional imaging for improved patient safety.