Determination of the Range and Spread-Out Bragg Peak Width of Proton Beams Using a Large-Volume Liquid Scintillator
Thomas Henry1, Daniel Robertson1, François Therriault-Proulx1
1Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
Purpose:
To determine the range, spread-out Bragg peak (SOBP) width, and output of a passive-scattering proton beam with a liquid scintillator detector, without the need for quenching correction.
Materials And Methods:
The depth-light profiles of 3 beam energies (140, 160, and 180 MeV) with 6 SOBP widths at each energy, produced in a 20 × 20 × 20-cm3 liquid scintillator tank, were collected by a charge-coupled device camera. By defining landmarks on the light signals, measured ranges and SOBP widths were acquired. A linear dependence was found between nominal and measured properties, and calibration factors were obtained by comparing those properties. The daily output stability and reproducibility of the liquid scintillator detector were studied by conducting 8 repeated measurements over 2 weeks in a 60Co beam.
Results:
The beam ranges were determined with submillimeter accuracy without the need for any correction. The maximum difference between the measured and nominal range was 1.0 mm. The mean difference between the measured and nominal SOBP widths after correction was 0.1 mm (σ = 1.8 mm), with a maximum difference of 3.5 mm. The light output was reproducible with an SD of 0.14%.
Conclusions:
The method described here makes it possible to quickly and accurately determine the range and SOBP width of a passive-scattering proton beam in a liquid scintillator, without the need for quenching correction. In addition, the detector proved to be reliable over time, showing good output consistency with a high degree of precision.
