Breast conserving surgery (BCS) is a common treatment option for women with early-stage breast cancer, but these procedures have high and variable reoperation rates due to positive margins. Current tumor localization technologies do not provide real-time spatial information about the tumor boundary, emphasizing the need for additional navigation tools. This work proposes an image-guidance system for BCS that combines stereo camera soft tissue monitoring with nonrigid registration to account for misalignments from soft-tissue deformations. The guidance system integrates an optical tracking sensor and a 3D stereo-camera sensor for surgical field monitoring. A custom user interface and display, developed using 3D Slicer, facilitates data collection and visualization of patient-specific imaging data and models. Near real-time deformable correction is driven by tissue displacement measurements and compensates for breast shape change. The feasibility and effectiveness of the guidance system are demonstrated through breast phantom deformation experiments that simulated tissue deformations. In 4 deformation states, 3D stereo-camera sensor data is collected, and imaging data is deformed in near real-time. Evaluation results show a reduction in fiducial and surface registration errors after deformable correction compared to conventional rigid registration approaches. The guidance system is then demonstrated on a healthy volunteer, where data collection and nonrigid correction are performed in a mock intraoperative setting. Overall, the proposed system achieved data collection and navigation capabilities compatible with current BCS workflows. However, quantitatively measuring navigation accuracy and clinical value is not addressed here and should be the focus of future work.
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