Monte Carlo dosimetric parameter study of a new (32)P brachytherapy source

Area of Science:

• Medical Physics
• Nuclear Medicine
• Radiotherapy

Background:

• A novel catheter-based phosphorus-32 ((32)P) brachytherapy source has been developed for high-dose-rate afterloading applications.
• This source is intended for the treatment of liver cancer, a significant clinical need.

Purpose of the Study:

• To present comprehensive dosimetric data for the new (32)P brachytherapy source.
• To validate the source's characteristics using the Geant4 Monte Carlo (MC) simulation toolkit.
• To provide data essential for clinical implementation and treatment planning.

Main Methods:

• The (32)P source, with dimensions 0.50 cm length and 0.08 cm diameter, encapsulated in Teflon, was simulated.
• Geant4 MC code was employed to calculate absorbed dose within a 30-cm radius water phantom.
• Dosimetric data were generated following the formalism of AAPM TG60 and TG149.

Main Results:

• Key dosimetric data including reference absorbed dose rate, radial dose function (0.10-0.50 cm), and anisotropy function (θ: 0-90°, r: 0.10-0.35 cm) were determined.
• The dose rate at the reference point for the unsheathed (32)P source was calculated as 1.2660 ± 0.0006 cGy s⁻¹ mCi⁻¹.
• The calculated radial dose function showed good agreement with other (32)P sources, with an average difference of 1.78%.

Conclusions:

• Essential dosimetric data for the new (32)P brachytherapy source have been successfully generated.
• These data are crucial for the integration of this new source into clinical treatment-planning systems.
• The study provides foundational information for the safe and effective use of this novel brachytherapy source in liver cancer treatment.