Dosimetric precision of an ion beam tracking system

Area of Science:

• Medical Physics
• Radiation Oncology
• Particle Therapy

Background:

• Motion mitigation is crucial for scanned ion beam therapy of moving tumors.
• GSI developed a beam tracking system for scanned carbon beams to address this challenge.

Purpose of the Study:

• To analyze the dosimetric precision of a novel beam tracking system for scanned carbon ion therapy.
• To validate the system's performance in compensating for intra-fractional tumor motion.

Main Methods:

• Integrated a beam tracking system into the GSI scanned carbon ion therapy unit.
• Assessed motion compensation using radiographic films, a range telescope, ionization chambers, and cell samples.
• Conducted measurements with both stationary and moving detectors.

Main Results:

• Beam tracking demonstrated high dosimetric precision, with ionization chamber measurements showing a mean relative difference of 0.3%.
• Film responses confirmed preserved lateral dose gradients, and range telescope data agreed with Bragg peak depth under motion.
• Cell survival experiments showed minimal differences between beam tracking and stationary measurements within the target volume.

Conclusions:

• The developed beam tracking system has been successfully integrated and fully functional.
• Experimental validation confirmed the system's dosimetric accuracy and biological effectiveness for scanned carbon ion therapy.