Ir-192 HDR transit dose and radial dose function determination using alanine/EPR dosimetry

Area of Science:

• Medical Physics
• Radiation Oncology
• Dosimetry

Background:

• High dose rate (HDR) brachytherapy involves source movement, delivering an uncalculated "transit dose" during positioning.
• This transit dose, dependent on various factors, can increase the delivered dose by up to 5% compared to the planned absorbed dose.
• Accurate dosimetry is crucial for accounting for this transit dose in treatment planning.

Purpose of the Study:

• To evaluate the transit dose in HDR brachytherapy using alanine-electron paramagnetic resonance (EPR) dosimetry.
• To determine the radial dose function using the same dosimetric system.
• To compare the results with existing data from TLD measurements and Monte Carlo simulations.

Main Methods:

• Utilized the alanine-EPR dosimetric system with analysis of the first derivative of the signal.
• Evaluated the transit dose for an HDR brachytherapy system.
• Determined the radial dose function to assess geometric dose degradation around the source.

Main Results:

• The evaluated transit dose using alanine-EPR was consistent with previous TLD measurements.
• The determined radial dose function showed better agreement with Monte Carlo simulations compared to TLD measurements.
• The alanine-EPR system proved effective for evaluating transit dose and radial dose function in HDR brachytherapy.

Conclusions:

• Alanine-EPR dosimetry is a reliable method for assessing transit dose in HDR brachytherapy.
• The findings support the use of alanine-EPR for more accurate dose calculations, potentially improving treatment planning.
• The results highlight the importance of considering transit dose and validate the accuracy of alanine-EPR against advanced simulation techniques.