Dynamic Modulated Brachytherapy (DMBT) Balloon Applicator for Accelerated Partial Breast Irradiation

Area of Science:

• Medical Physics
• Radiation Oncology
• Biomedical Engineering

Background:

• Accelerated partial breast irradiation (APBI) is a common treatment for early-stage breast cancer.
• Current APBI techniques, such as those using the Contura applicator, aim to deliver precise radiation doses while minimizing damage to surrounding tissues.
• Optimizing dose delivery and organ-at-risk (OAR) sparing remains a key challenge in APBI.

Purpose of the Study:

• To introduce a novel high-dose-rate brachytherapy applicator designed for balloon-based dynamic modulated brachytherapy (DMBT).
• To evaluate the dosimetric benefits of this new DMBT applicator compared to the established Contura applicator for APBI.
• To demonstrate the potential for improved OAR sparing and enable advanced treatment delivery techniques.

Main Methods:

• A new DMBT balloon applicator was designed with a fixed central channel for in-vivo dosimetry and a dynamic outer channel for adjustable dwell position placement.
• Retrospective analysis of 13 APBI treatment plans using the Contura applicator for early-stage breast cancer patients.
• New treatment plans were generated using the DMBT device, optimizing for OAR (ribs and skin) dose reduction while maintaining target coverage.

Main Results:

• The DMBT applicator achieved comparable target coverage to the Contura applicator.
• Significant mean dose reductions were observed for ribs (6.70%) and skin (5.13%) using the DMBT device.
• A threshold separation of 12 mm between the balloon and OARs was identified, below which significant dosimetric improvements were noted.

Conclusions:

• The novel APBI DMBT applicator demonstrates superior OAR sparing capabilities compared to current methods, particularly when OARs are in close proximity to the target volume.
• This advancement in brachytherapy applicator design facilitates comparable target coverage while enhancing safety.
• The DMBT balloon holds potential for enabling novel dynamic high-dose-rate treatment delivery and supporting ultrahypofractionated radiation regimens.