A method to increase the nominal range resolution of a stack of parallel-plate ionization chambers

Area of Science:

• Medical Physics
• Radiation Oncology
• Detector Physics

Background:

• Ion beam therapy requires precise range determination for accurate dose delivery.
• Current detector prototypes using parallel-plate ionization chambers (PPIC) offer discrete Bragg curve approximations.
• Limited range resolution can impact treatment planning and efficacy.

Purpose of the Study:

• To present a new data processing method for increasing range resolution (MIRR) in PPIC detector stacks.
• To evaluate the MIRR's performance using Monte Carlo simulations and experimental data.
• To assess the impact of beam energy and phantom inhomogeneities on the MIRR.

Main Methods:

• Developed a method (MIRR) to deduce Bragg curve peak position from adjacent PPIC signal ratios.
• Utilized Monte Carlo simulations to generate Bragg curves for method development.
• Validated the MIRR with experimental data from a wedge-shaped phantom using carbon ion beams.

Main Results:

• The MIRR method successfully increases the range resolution of the PPIC detector stack.
• Achieved an enhanced range resolution of 0.7 mm PMMA equivalent (0.8 mm water equivalent).
• Quantitatively evaluated systematic errors and signal noise impacts on the MIRR.

Conclusions:

• The MIRR method offers a significant improvement in range resolution for transmission imaging in ion beam therapy.
• This technique enhances the precision of Bragg curve approximation, aiding in treatment verification.
• The MIRR is a valuable tool for optimizing detector performance in particle therapy applications.