An automated system for registration and fusion of 3D ultrasound images during cervical brachytherapy procedures

Abstract

High dose-rate brachytherapy is a typical part of the treatment process for cervical cancer. During this procedure, radioactive sources are placed locally to the malignancy using specialized applicators or interstitial needles. To ensure accurate dose delivery and positive patient outcomes, medical imaging is utilized intra-procedurally to ensure precise placement of the applicator. Previously, the fusion of three-dimensional ultrasound images has been investigated as an alternative volumetric imaging technique during cervical brachytherapy treatments. However, the need to manually register the two three-dimensional ultrasound images offline resulted in excessively large registration errors. To overcome this limitation, we have designed and developed a tracked, automated mechatronic system to inherently register three-dimensional ultrasound images in real-time. We perform a system calibration using an external coordinate system transform and validate the system tracking using a commercial optical tracker. The results of both experiments indicated sub-millimeter system accuracy, indicating the superior performance of our device. Future work for this study includes performing phantom validation experiments and translating our device into clinical work.