Use of an ultrasound imaging device within the applicator to evaluate placement and support treatment planning for breast brachytherapy and intraoperative radiation therapy.

Purpose: We evaluated the use of ultrasound imaging within a brachytherapy applicator as a method for applicator positioning, evaluation, and treatment planning in a series of in vitro, cadaver, and human studies.

Methods And Materials: We evaluated the performance of a prototype system comprising a small ultrasound imaging catheter inserted within the lumen of a balloon brachytherapy catheter. We tested the device in an ultrasound phantom, in human breast tissue, and in an endoscopic ultrasound catheter in cadaveric breast tissue. We evaluated the visualization of adjacent tissue to consider future development of a similar system for use in brachytherapy and intraoperative radiation therapy.

Results: Based on the ultrasound images obtained in an ultrasound phantom, cadaveric breast, and human participants, we observed that an ultrasound imaging catheter placed within the lumen of a brachytherapy applicator can effectively image adjacent tissue, ribs, and air voids, with appropriate quality to support clinical use. We observed high correlation in clinically useful information detected on ultrasound and comparative CT, with ultrasound spatial resolution near 1 mm (spatially variant).

Conclusions: The findings from our pilot work suggest that real-time ultrasound imaging, operated from within the applicator, is a promising technique for image guidance and treatment planning during brachytherapy and intraoperative radiation therapy. Further expansion of this technology for clinical use will require development of a cohesive system of components to suit specific clinical applications.