Originally Published EMDM November 2005
ENGINEERING INSIGHT
Robotic System Enables Precise Delivery of Radiation Therapy
The radiosurgical device’s submillimetre positioning tolerances make it possible to perform otherwise problematic procedures.
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| Kuka Controls offers a robot and associated software that controls the precise positioning of a linear accelerator that produces tightly focused radiation beams to treat tumours. |
Motion control technologies combined with precise diagnostic x-ray beams are providing cancer patients with new hope. The CyberKnife Stereotactic Radiosurgery device, developed by Accuray (Sunnyvale, CA, USA), enables tumour ablation without incisions or loss of blood. Performed in an outpatient setting, the procedure’s tight targeting tolerances allow the treatment of patients who are too young to immobilize for frame-based radiosurgery or who have already received the maximum allowable dose of radiation for certain organs. Precise positioning of the radiation beams is made possible by the integration of robotics and control software supplied by Kuka Controls GmbH (Weingarten, Germany).
Traditional stereotaxy uses an external frame to locate points within the brain during neurosurgical procedures. Until recently, stereotactic radiosurgery also relied on an external frame to locate and treat tumours and lesions. Because the radiation is precisely focused, this procedure sharply reduces exposure to adjacent healthy tissues and organs compared with other forms of treatment. The CyberKnife system has taken the technology a step further by eliminating the rigid frame.
Real-time Performance
Accuray’s technology relies on the cranium (or small metallic markers implanted in the tumour for extracranial applications) as the frame of reference. X-ray cameras are mounted underneath and on both sides of the patient, who is placed on a movable table. Kuka provides the robotic system, the control and user-interface software, and the software that allows the two operating systems to communicate.
Positioning accuracy at the submillimetre level is enabled by the VxWin software extension, which provides stability and real-time performance. The open architecture of the software allows easy integration of industry-standard inputs and outputs with the robot, including Ethernet-based communication with the external workstation.
The system continuously updates the target position of a miniature linear accelerator by comparing real-time diagnostic x-ray images with previously generated computed tomography scans. The updated target position is continually relayed to the control system, which, in turn, repositions a linear accelerator attached to the robot. Hundreds of tightly focused radiation beams are produced by the linear accelerator during the procedure. This technique enables the use of a noninvasive flexible mask in lieu of the traditional rigid frame.
“We set very high standards for the reliability and accuracy of the robot that controls the positioning of the linear accelerator,” says Accuray president and CEO Euan Thomson. “We were impressed not only by the performance of the Kuka system, but by [the company’s] commitment to assist in the system’s integration into the CyberKnife system.”
Range of Applications
The maneuverability of the robot and the submillimetre positioning tolerances that can be achieved has generated interest in the technology for a variety of applications. The system allows for more complete coverage of complex target volumes than traditional methods while minimizing the effects on surrounding tissues and organs. The robotic arm’s six degrees of freedom also make previously unreachable tumors accessible for treatment. The CyberKnife system can even compensate for patient breathing with the optional Synchrony Respiratory Tracking device.
Kuka Roboter robots are used worldwide in a range of industries. Kuka Controls offers two nonproprietary COTS software extensions: VxWin and CeWin. They allow designers to combine Windows XP/2000 with either Windows CE or Wind River VxWorks real-time operating systems on a single CPU. Open programming interfaces and development environments, full Microsoft and Wind River tool support, and technical support and documentation allow developers to provide cost-effective solutions, adds the company.
To learn more about Kuka Controls GmbH, visit EMDM's RequestLink.
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