Microdosimetric characterization of a clinical helium beam using a MicroPlus-Bridge detector and a diamond detector...

Area of Science:

• Medical Physics
• Radiation Oncology
• Biophysics

Background:

• Helium ion therapy offers precise dose delivery and enhanced biological effectiveness.
• Microdosimetry is crucial for understanding radiation quality and biological impact.
• Characterizing clinical helium ion beams is essential for optimizing treatment planning.

Purpose of the Study:

• To conduct a microdosimetric analysis of a clinical helium ion beam.
• To assess radiation quality across a spread-out Bragg peak (SOBP).
• To provide experimental data supporting helium ion therapy's biological effectiveness.

Main Methods:

• Microdosimetric spectra were measured using silicon and diamond detectors within the SOBP.
• Dose-mean lineal energy (yD) and frequency-mean lineal energy (yF) were calculated.
• Monte Carlo simulations (Geant4) and the microdosimetric kinetic model were used for validation and RBE estimation.
• Clonogenic assays (SAOS-2, U2OS) were performed to benchmark RBE predictions.

Main Results:

• Microdosimetric measurements showed increasing yD values along the beam path, peaking at the SOBP's distal edge.
• Simulations confirmed the experimental findings regarding linear energy transfer distribution.
• Estimated RBE10 values from detectors closely matched experimental clonogenic assay data.

Conclusions:

• Solid-state detectors are valuable tools for helium beam characterization.
• Microdosimetry enhances radiobiological modeling for ion beam therapy.
• Results support the clinical application of helium ion therapy for precise treatments with maximal healthy tissue sparing.