Towards comprehensive characterization of Cs-137 Seeds using PRESAGE® dosimetry with optical tomography

Area of Science:

• Medical Physics
• Radiation Dosimetry
• Brachytherapy

Background:

• Accurate characterization of brachytherapy sources is crucial for effective radiation therapy.
• Traditional dosimetry methods can be complex and time-consuming.
• Optical CT offers a promising alternative for high-resolution 3D dose reconstruction.

Purpose of the Study:

• To develop and validate a method for directly measuring radial dose and anisotropy functions of brachytherapy sources.
• To assess the accuracy of polyurethane-based dosimeters read out with optical CT for brachytherapy dosimetry.

Main Methods:

• Utilized PRESAGE® polyurethane dosimeters with a central channel for a Cesium-137 brachytherapy source.
• Irradiated dosimeters in water and performed pre- and post-irradiation optical CT scans using the Duke Large field of view Optical CT Scanner (DLOS).
• Reconstructed 3D dose distributions with 0.5mm isotropic voxel size to determine radial dose and anisotropy functions.

Main Results:

• Measured radial dose factors agreed with published data within 3% for radii from 0.5-3.0cm.
• Anisotropy function measurements showed agreement within 4%, with deviations observed near 0°/180° and radii >3cm.
• Simulations suggest potential for 8-fold dose increase while maintaining optical CT signal integrity.

Conclusions:

• Polyurethane dosimeters combined with optical CT provide a direct and accurate method for measuring brachytherapy source radial dose and anisotropy functions.
• The technique shows high potential for brachytherapy quality assurance and source characterization.
• Further optimization, including dose levels and dosimeter size, can enhance measurement accuracy.