Originally Published EMDM March/April 2005
Technology News
Proton-Beam Therapy System Achieves 0.5-mm Positioning Accuracy |
| A gantry for a proton-beam irradiation machine is prepared for Europe’s first proton-beam therapy centre in München, Germany. |
Proton-beam therapy (PBT) can treat tumors more effectively than conventional radiation because it causes less collateral damage. To succeed, the treatment requires that the patient be positioned with extreme accuracy in relation to the proton beam. Consequently, the motion control system is a critical component of PBT equipment. With assistance from Baldor (Feuerthalen, Switzerland), IPG Automation Engineering (Winterthur, Switzerland) has designed a novel eight-axis control system for PBT devices.
The system has been built into equipment being used at Europe’s first PBT facility, the Rinecker Proton Therapy Centre in München, Germany. At the time of publication, patient treatment was expected to commence in March 2005.
PBT is especially effective because protons produce more energy as they slow down. The amount of energy peaks at the target point, allowing delivery of radiation to a very small area. Compared with traditional methods, less radiation reaches normal tissue.
A 100-t steel cylinder and a gantry with magnets that guide the accelerated proton beam make up the machine’s core. Patients are placed in the cylinder, where they are positioned within 0.5 mm of the beam path. To achieve this degree of precision, the table is equipped with x, y, and z rotation and pitch and roll axes controls driven by closed-loop servomotors. The motion control system designed by IPG incorporates components from Baldor and is compatible with the firm’s Mint language motion commands. To ensure open access to the source code, IPG opted for a Linux system.
IPG developed a new Linux driver for Baldor’s Mint-compatible C library. Baldor’s PCIbus-based multiaxis motion controller receives motion commands from the Linux-based application. The control program converts polar coordinates into the Cartesian ones required for three-dimensional patient positioning.
“The Mint language’s sophisticated motion functions helped to simplify [the system],” notes IPG’s head of automation engineering Alexander Ferro. “It allowed us to concentrate our efforts on developing the application-specific algorithms that underpin the positioning movements and on the overall control system.”
Baldor and IPG have a history of collaboration. Having provided strong technical support to IPG during past projects led to this contract, says Daniel Berg of Baldor. “In this case, we helped them to port Mint onto the Linux platform. This technology is now available for use by our wider customer base,” adds Berg.
Copyright ©2005 European Medical Device Manufacturer
