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Real-Time Telerobotic 3D Ultrasound for Soft-Tissue Guidance Concurrent with Beam Delivery

D Hristov

D Hristov1*, J Schlosser1, C Kirmizibayrak1, V Shamdasani2, K Salisbury1, D Chang1, S Metz2, (1) Stanford University, Stanford, CA, (2) Philips Ultrasound, Bothell, WA

WE-A-BRA-4 Wednesday 8:00:00 AM - 9:55:00 AM Room: Ballroom A

Managing internal anatomy motion due to physiological random or quasi-periodical processes is a critical challenge in external beam radiation therapy especially in the context of single- or few-fraction ablative regiments for abdominal targets. Existing and emerging technologies for localizing abdominal targets during beam delivery employ tracking of implanted fiducial markers, tracking of external surrogates, or guidance via magnetic resonance images. However, these technologies cannot meet the challenge of providing real-time, volumetric, non-invasive, markerless soft-tissue image guidance to existing radiation delivery platforms.

Diagnostic ultrasound is a safe, non-ionizing, non-invasive modality widely used in image-guided cancer interventions that has significant potential to address this challenge. Modern matrix array transducers can generate real-time soft-tissue single plane (2D), cross-plane, and volumetric (3D) data thus allowing optimization of frame rate, field-of-view and image quality for the purposes of motion monitoring and tracking. Furthermore, digital navigation links that stream live data to other devices enable the development of real-time image-guidance applications on dedicated interventional workstations with no interference to the imaging process.

Based on these capabilities we have been developing and evaluating a novel approach that combines robotics with diagnostic ultrasound imaging. It uses a customized add-on human-safe robotic manipulator to control the pressure and pitch of an abdominal probe while avoiding gantry collisions. The manipulator can maintain probe pressure and pose autonomously or interactively via a haptic device that is integrated to remotely control the robotic manipulator outside the therapy room. The transducer is optically tracked to localize the ultrasound images in the coordinate system of the delivery device. Image processing techniques are implemented to monitor anatomy displacements in real time. The approach is being evaluated with regard to imaging robustness, interference with delivery devices, impact on treatment plans, localization accuracy, and temporal lag.

Learning objectives:

1. Understand how tele-robotic 2D/3D ultrasound imaging and appropriately designed workflow can enable real-time soft-tissue image guidance concurrent with radiation delivery.
2. Recognize different imaging (2D/cross-plane/3D) and image-processing approaches to real-time anatomy motion monitoring and appreciate their performance for localization and tracking.
3. Recognize interferences between the radiation delivery system and the tele-robotic imaging system and appreciate their magnitude and mutual impact.

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