SU-E-T-312: Optically Stimulated Luminescent Dosimeter Performance in High Dose Rate Brachytherapy

Area of Science:

• Medical Physics
• Radiation Oncology
• Dosimetry

Background:

• Optically stimulated luminescent dosimeters (OSLDs) are widely used in megavoltage radiotherapy.
• Their performance in high dose rate (HDR) brachytherapy, characterized by kilovoltage energies and high dose gradients, remains underexplored.

Purpose of the Study:

• To evaluate the suitability of OSLDs for in vivo dosimetry in Ir-192 HDR brachytherapy.
• To assess OSLD performance concerning dose rate dependence, linearity, and angular dependency in HDR brachytherapy conditions.

Main Methods:

• Commercially available nanoDotTM OSLDs were irradiated using an Ir-192 source.
• Various geometries were employed, including those simulating accelerated partial breast irradiation, to determine dose rate and angular dependence.

Main Results:

• OSLD response was linear up to 200 cGy and slightly supra-linear up to 600 cGy.
• Dose rate independence was observed.
• A slight, manageable angular dependence was noted, particularly in 'edge-on' scenarios, attributed to physical factors.

Conclusions:

• OSLDs demonstrate reliable dosimetric performance within the clinical dose range for HDR brachytherapy.
• Their re-readability, cost-effectiveness, and dose-rate independence make them suitable for in vivo measurements.
• Careful consideration of measurement geometry is advised to mitigate angular dependence.