Development of a robot-assisted ultrasound-guided radiation therapy (USgRT)

Radiation treatment is improved by the use of image-guided workflows. This work pursues the approach of using ultrasound (US) as a real-time imaging modality. The primary focus of this study is to develop and test a breathing and motion control for a robotic-guided US transducer. All control functions of the robot and the US image processing were then integrated into one software platform enabling US-guided radiation therapy.

The robot (KUKA LBR iiwa 7 R800) and the US image processing workflows were integrated into the Medical Interaction Toolkit (MITK) (Nolden et al. in Int J Comput Assist Radiol Surg 8(4):607-620, 2013). The positions of the US probe were tracked with an optical tracking system. As a main function of robot positioning control, a highly sensitive breathing and motion compensation method was developed using KUKA's robotic application programming interface. The resulting autonomous robot motions were tested by the use of defined breathing patterns with two volunteers. Furthermore, a filter pipeline for 3D US image processing with MITK was developed. Thus, image registration of US images and previously acquired planning image data was enabled.

The implemented breathing and motion compensation feature was successful with the addition of the remote rotating, translating capability of the US probe. Desired force applied to the US probe, and thus to the patient, is stable and enables a continuous US imaging. The developed filter pipeline for image processing facilitates registration and display of planning data and US image data in one graphical user interface.

A stable and robust method for motion compensation for robot-assisted US imaging was developed and tested successfully. This is a first step toward the safe use of autonomous robot motions in interaction with patients. Furthermore, main software components were integrated into a single platform and used with the purpose of ultrasound-guided radiation therapy.