Immobilization and Catheter Guidance for Breast Brachytherapy Using Patient-Specific Templates

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Pompeu-Robinson, Alexandra
Immobilization , Breast cancer , Guidance , Patient-specific template , Brachytherapy , Radiotherapy
Brachytherapy is an important method of breast cancer treatment; however, improvements in both treatment planning and delivery are needed. The procedure involves insertion of catheters in the tumor site, which, in current practice, is prone to clinically significant error. In order to improve on contemporary catheter placement accuracy, integration of pre-operative imaging, supplemented by computerized surgical planning and mathematical optimization were used to develop and test an intra-operative immobilization and catheter guidance system. A custom-template specific to each patient with optimally-placed guide-holes for catheter insertion was designed and fabricated for use on phantom studies. Template creation is based on a virtual reality reconstruction of the patient's anatomy from computed tomography imaging. The template fits on the patient's breast, immobilizing the soft tissue, to provide pre-planned catheter insertion holes for guidance to the tumor site. Agar-based phantom and target models were used for quantitative validation of the template using computed tomography imaging for template planning and validation. Planned catheter tracks were compared to post-insertion image data and distance measurements from target location were used to create an error measure. Using the latest template design spanning multiple experiments resulted in a mean of 2.6 mm, 95%, CI =3.1-2.2, which is within the clinically acceptable range of 3 mm, as validated with our clinical collaborators. Validation of the brachytherapy template on phantom tissue produced clinically acceptable results. Use of a patient-specific template for breast brachytherapy is feasible and may improve the procedure accuracy and outcome. This work has been a proof-of-concept, providing evidence to support moving forward with the next phase of patient-specific breast template trials for use in brachytherapy.
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