A respiratory-gated treatment system for proton therapy

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Technology

Background:

• Proton therapy provides superior dose conformity but is highly sensitive to radiological depth variations.
• Respiratory motion in lung, liver, and mediastinum treatments can significantly alter proton dose distribution.
• Existing methods may not fully address motion-induced uncertainties in proton therapy.

Purpose of the Study:

• To implement and commission a respiratory-gated system for range-modulated proton therapy fields.
• To ensure complete modulation cycles within each gating window for accurate depth-dose distribution.
• To evaluate the system's performance and time delays in managing respiratory motion.

Main Methods:

• Development and commissioning of a respiratory-gated system for proton therapy.
• Design ensuring complete modulation cycles within each gating interval.
• Measurement of time delays for system components (65-195 ms).
• Time-resolved dose measurements and film tests to assess gating effectiveness.

Main Results:

• The implemented gating system ensures complete modulation cycles per gate.
• System time delays were quantified, ranging from 65 to 195 ms.
• Time-resolved measurements and film tests confirmed the gating effect on dose distribution.

Conclusions:

• Respiratory gating is feasible and effective for range-modulated proton therapy.
• The system helps maintain planned depth-dose distributions despite respiratory motion.
• This technology has the potential to improve treatment accuracy for sites affected by breathing motion.