Improved simultaneous LET and dose measurements in proton therapy

Area of Science:

• Medical Physics
• Radiation Dosimetry
• Particle Therapy

Background:

• Proton therapy requires precise dose and linear energy transfer (LET) measurements for accurate treatment planning.
• Optically stimulated luminescence dosimeters (OSLDs) offer potential for high-precision dosimetry but require correction for LET-dependent effects like ionization quenching.
• Existing methods for LET estimation using OSLDs can be limited by variations in dose and LET, impacting measurement accuracy.

Purpose of the Study:

• To enhance the precision of LET measurements using [Formula: see text] OSLDs in proton beams.
• To improve OSL dosimetry accuracy by correcting for LET-dependent ionization quenching.
• To establish an automated method for OSLD readout and correction in proton dosimetry.

Main Methods:

• Irradiation of [Formula: see text] OSLDs in spot-scanning proton beams across a range of doses and LET values (0.4-6.5 keV/µm).
• Utilized pulsed optically stimulated luminescence (OSL) to measure blue (F-center) and UV ([Formula: see text]-center) emission bands.
• Employed a UV/blue signal ratio for LET estimation and implemented automated OSL reader with reference irradiation for individual OSLD corrections.

Main Results:

• Reduced average deviation between simulated and measured LET values from 5.5% to 3.5% by irradiating OSLDs at constant doses.
• Minimized signal variation for LET estimation and quenching correction from 0.9% to 0.6% using the automated procedure.
• Quenching-corrected OSLD doses showed agreement with ionization chamber measurements within uncertainties.

Conclusions:

• Automated OSLD corrections significantly improve LET estimation and ionization quenching corrections in proton dosimetry up to 230 MeV.
• This method enables accurate LET estimation across different dose levels for the first time.
• The developed technique enhances the reliability and precision of OSL dosimetry in clinical proton therapy applications.