A major advance in the treatment of cancer involves a process known as IntraOperative Electron Radiation Therapy (IOERT), which delivers a highly concentrated and precise dose of radiation during cancer surgery. This therapy is applied immediately after the tumor is removed to reduce and possibly eliminate the need for post-operative external radiation therapy. Sunnyvale, Calif-based IntraOp Medical, which manufactures the Mobetron IOERT machine, has recently developed its second generation Mobetron machine using an embedded PC to automate the IOERT process.
The new Mobetron machines are equipped with Beckhoff’s DIN rail-mountable CX5020 Embedded PC, which features the 1.6 GHz Intel Atom Z530 processor. The Mobetron embedded PCs run TwinCAT PLC software to automate the IOERT processes and are directly connected to EtherCAT terminals, which constitute the machine’s I/O system. Additional I/O nodes use EK1100 EtherCAT Couplers to distribute I/O across the machine.
“The combination of the CX5020, EtherCAT and TwinCAT enables very fast control processes in the low microsecond range,” says Shura Kretchetov, physicist at IntraOp Medical. “This has a direct positive impact on the performance of the Mobetron systems in the field.”
Running on the CX5020 Embedded PCs, TwinCAT is used to handle all automated functions on the Mobetron, including control of a small linear accelerator used to deliver electron-beams to the affected areas. Because electron-beams penetrate at a shallower depth than x-ray beams used in conventional radiation therapy, these radiation treatments can be given in any operating room without the need for protective radiation shields.
The EtherCAT industrial Ethernet system was added to the Mobetron via distributed I/O terminals for high speed digital and analog data acquisition. All system and process data is gathered by EtherCAT in the Mobetron to ensure precise treatment of cancerous areas. In addition to the data gathering functionality, IntraOp Medical uses Beckhoff’s EL7031 and EL7041 EtherCAT stepper motor control terminals paired with AS1060 series stepper motors to create a stepper system that doesn’t require separate amplifiers. The stepper terminals also ensure precise control and alignment of the Mobetron’s electron beam.
IntraOp Medical uses some EtherCAT Terminals in the Mobetron to establish connectivity to other common communication protocols such as Profibus and serial communications. The Beckhoff EL6731 Profibus slave terminal integrates Profibus devices to the EtherCAT network without requiring the addition of PCI cards. Similarly, the EL6021 serial interface terminal facilitates the connection of devices with RS422 or RS485 interfaces. Beckhoff claims that, regardless of the compatible network/fieldbus that EtherCAT is connected to, data from all the equipment can be passed to the CX5020 master controller with standard Ethernet media.
“Between our generation one machines (without Beckhoff) and generation two machines (with Beckhoff), we saved around 36 hours of engineering and installation time per machine, enabling us to ship twice as many machines per month,” Kretchetov says.
