Dose verification for liver target volumes undergoing respiratory motion

Area of Science:

• Radiation oncology
• Medical physics
• Respiratory motion management

Background:

• Respiratory motion significantly impacts radiotherapy dose delivery to abdominal targets.
• Treating liver tumors near the diaphragm is challenging due to large movements and density variations.

Purpose of the Study:

• To evaluate the accuracy of radiation dose delivery to superior liver tumors using passive respiratory monitoring.
• To compare conformal, VMAT, and IMRT techniques without gating technology.

Main Methods:

• An in-house respiratory phantom simulating lung-liver anatomy was used.
• Point and plane dose measurements were performed using an ionisation chamber and film.
• Treatment plans were calculated using Monaco TPS for various breathing rates (8, 14, 23 bpm).

Main Results:

• Conformal delivery protocol was confirmed as suitable.
• VMAT was found to be a viable and superior alternative to IMRT for superior liver lesions.
• Measurements underscored the necessity of respiratory management to avoid margin discrepancies.

Conclusions:

• Passive respiratory monitoring and VMAT offer effective solutions for treating liver tumors affected by respiratory motion.
• Careful respiratory management is crucial to ensure accurate dose delivery and minimize side effects.