title: Calculations and measurements of the scintillator-to-water stopping power ratio of liquid scintillators for use in proton radiotherapy.
abstract: Liquid scintillators are a promising detector for high-resolution three-dimensional proton therapy dosimetry. Because the scintillator comprises both the active volume of the detector and the phantom material, an ideal scintillator will exhibit water equivalence in its radiological properties. One of the most fundamental of these is the scintillator's stopping power. The objective of this study was to compare calculations and measurements of scintillator-to-water stopping power ratios to evaluate the suitability of the liquid scintillators BC-531 and OptiPhase HiSafe 3 for proton dosimetry. We also measured the relative scintillation output of the two scintillators. Both calculations and measurements show that the linear stopping power of OptiPhase is significantly closer to water than that of BC-531. BC-531 has a somewhat higher scintillation output. OptiPhase can be mixed with water at high concentrations, which further improves its scintillator-to-water stopping power ratio. However, this causes the solution to become cloudy, which has a negative impact on the scintillation output and spatial resolution of the detector. OptiPhase is preferred over BC-531 for proton dosimetry because its density and scintillator-to-water stopping power ratio are more water equivalent.
authors.affiliation: Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA ; The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX 77030, USA.
authors.forename: W Scott
authors.initials: WS
authors.lastname: Ingram
authors.affiliation: Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Robertson
authors.affiliation: Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA ; The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX 77030, USA.
authors.forename: Sam
authors.initials: S
authors.lastname: Beddar
keywords: SRIM; Scintillation dosimetry; liquid scintillators; proton therapy