Calibration of multiple LDR brachytherapy sources

Area of Science:

• Medical Physics
• Radiation Oncology
• Nuclear Medicine

Background:

• The increasing use of prepackaged low dose rate brachytherapy sources necessitates reliable verification methods.
• Medical physicists are responsible for ensuring accurate source strength before patient treatment.

Purpose of the Study:

• To experimentally evaluate the impact of different multiseed geometries on source strength measurements.
• To develop practical verification methods for prepackaged brachytherapy sources.

Main Methods:

• Review of existing guidelines for prepackaged brachytherapy sources.
• Experimental measurement of multiseed strands, coils, and sterile seed cartridge packs using a well-type ionization chamber.
• Evaluation of measurement techniques for sources within needles, including removal into sterile inserts.

Main Results:

• Multiseed strands and coils (125I, 103Pd, 192Ir) can be accurately measured in chambers with long, uniform sensitive lengths.
• Sterile seed cartridge packs require a correction factor for accurate measurement.
• Sources within needles cannot be measured directly due to variations in needle composition and thickness; removal into sterile inserts is a viable alternative.

Conclusions:

• Practical methods for verifying the source strength of various prepackaged brachytherapy sources have been established.
• Correction factors are provided where necessary for accurate measurements.
• Maintaining sterility during measurement is crucial, especially when handling multiple seeds.