First In Vivo Monitoring of Helium-Ion Radiation Therapy With Secondary Ions

Area of Science:

• Medical Physics
• Radiation Oncology
• Particle Therapy

Background:

• Ion-beam radiotherapy, including protons and carbon ions, offers precise dose delivery for complex cancers.
• Helium ions are gaining interest for their distinct physical and radiobiological characteristics.
• Beam-range uncertainties in ion therapy arise from patient anatomical changes, necessitating robust monitoring.

Purpose of the Study:

• To perform the first in-vivo monitoring of helium-ion therapy using secondary ion tracking.
• To assess treatment reproducibility and identify potential sources of variation during helium-ion radiotherapy.
• To explore the potential of secondary ion monitoring for adaptive radiotherapy and dose optimization.

Main Methods:

• Developed and applied a method for tracking secondary ions emitted during helium-ion radiotherapy.
• Monitored a patient with a solitary fibrous tumor undergoing helium-ion therapy.
• Analyzed secondary ion distributions to evaluate treatment consistency between fractions.

Main Results:

• Achieved successful in-vivo monitoring of helium-ion therapy, confirming high treatment reproducibility for the patient.
• Detected significant differences in secondary ion distributions at the skull base and sphenoid sinus, possibly due to inter-fractional cavity filling.
• Demonstrated the feasibility of using secondary ion tracking for quality assurance in helium-ion treatments.

Conclusions:

• The first in-vivo monitoring of helium-ion therapy was successfully executed.
• Future work requires validation with regular CT scans and Monte Carlo simulations to link secondary ion signals to dose changes.
• This technique holds potential for improving adaptive radiotherapy and ensuring treatment efficacy in helium-ion therapy.