Gated CT imaging using a free-breathing respiration signal from flow-volume spirometry

Area of Science:

• Medical Imaging
• Radiation Oncology
• Respiratory Gating

Background:

• Respiration causes tumor motion artifacts in free-breathing CT scans.
• Inaccurate target volume delineation on CT planning images impacts radiation therapy efficacy.
• Active breathing control (ABC) systems utilize flow-volume spirometry for breath-holds.

Purpose of the Study:

• To develop and test a prototype for motion-gated CT acquisition using flow-volume spirometry.
• To evaluate the reduction of errors in target volume estimation caused by respiratory motion.
• To assess the clinical applicability of motion-gated CT in lung and abdominal cancer patients.

Main Methods:

• A prototype extending flow-volume spirometry for gated CT scans was developed.
• Motion phantoms simulated respiratory motion (3-5s periods, 0.5-2cm amplitudes).
• Gated and non-gated spiral and axial CT scans were acquired and compared.

Main Results:

• Phantom studies showed volume estimation errors up to 30% without gating, reduced to within 5% with motion-gated CT.
• Clinical cases (lung, abdomen) demonstrated reduced artifacts and volume differences up to 20% with gated scans.
• Gated CT scans showed improved structural overlap compared to free-breathing scans.

Conclusions:

• Flow-volume spirometry-based gating effectively reduces CT imaging artifacts caused by respiration.
• Motion-gated CT significantly improves the accuracy of target volume delineation for radiation therapy planning.
• This technique enhances precision in radiation oncology by minimizing motion-related errors.