Audiovisual biofeedback improves the correlation between internal/external surrogate motion and lung tumor motion

Area of Science:

• Medical Imaging and Radiation Oncology
• Respiratory Motion Management
• Biophysics

Background:

• Breathing motion causes variability in radiotherapy, impacting treatment accuracy.
• Respiratory surrogates (internal/external) are used for motion guidance.
• Audiovisual (AV) biofeedback aims to improve breathing motion reproducibility.

Purpose of the Study:

• To test if AV biofeedback improves the correlation between respiratory surrogates and tumors.
• To compare correlation under free breathing (FB) versus AV biofeedback guidance.
• To evaluate motion correlation with and without adjustments for phase shifts and tumor motion range.

Main Methods:

• 13 lung cancer patients underwent MRI during radiotherapy.
• Coronal and sagittal cine-MR images acquired across two sessions.
• External (abdomen) and internal (diaphragm, tumor) motion measured.
• Pearson's correlation coefficient calculated for abdomen-tumor and diaphragm-tumor.
• Correlations compared between FB and AV biofeedback conditions.

Main Results:

• AV biofeedback improved abdomen-tumor correlation by 11% (p=0.12) and diaphragm-tumor by 13% (p=0.02) vs. FB.
• With phase shift correction, AV biofeedback improved correlations by 15-17% (p<0.01).
• AV biofeedback with ≥5 mm tumor motion range showed 14-17% improvement (p=0.01-0.18).

Conclusions:

• AV biofeedback significantly enhances the correlation between respiratory surrogates and the tumor.
• This improvement is vital for accurate radiotherapy in thoracic regions.
• AV biofeedback is recommended for image-guided and MRI-guided radiotherapy utilizing respiratory surrogates.