Time-resolved in vivo dosimetry for source tracking in brachytherapy

Area of Science:

• Medical Physics
• Radiation Oncology
• Oncology

Background:

• Brachytherapy is a crucial treatment for prostate cancer.
• Accurate source placement is vital for effective brachytherapy.
• Real-time monitoring of brachytherapy sources is challenging.

Purpose of the Study:

• To demonstrate that brachytherapy source tracking is achievable using in vivo dosimetry.
• To enable real-time treatment monitoring in brachytherapy.

Main Methods:

• In vivo dosimetry with radioluminescent crystals was integrated into clinical high-dose-rate prostate brachytherapy.
• Dose rates were recorded every 50-100 ms.
• Measured doses and source-dosimeter distances were compared to expected values to determine needle position.

Main Results:

• Analysis of 305 needles and 3239 dwell positions from 20 treatments.
• Measured total doses varied by -4.7 ± 8.4% from expected values.
• Needle shifts were accurately determined for 304 out of 305 needles, with mean radial shift of 0.2 ± 1.1 mm and longitudinal shift of 0.3 ± 2.0 mm.

Conclusions:

• Time-resolved in vivo dosimetry provides geometric information on brachytherapy treatment progression.
• This technique can identify errors and uncertainties during treatment.
• Enables real-time monitoring for improved brachytherapy delivery.