Implementing EtherCAT for computed tomography featured medical devices

Computed tomography is used for diagnostic purposes in various fields: oncology, traumatology, dentistry, etc. Additionally, it is implemented to provide the information on the correct patient positioning relative to therapeutic equipment for example in brachytherapy or in image guided radiation therapy complexes. As a rule, such installations include an electric power drive system for gantry — moving part of the apparatus holding medical equipment: X-ray tube and detector, radiation head et al. Improving the event synchronization between the components of medical equipment and those to the motion control system opens up new abilities for control system architecture design. Implementing a single real time fieldbus such as EtherCAT for data exchange between the subsystems can enable high level of synchronization expediting the therapy procedure and improving safety. A platform for deploying EtherCAT in medical devices is proposed. It includes EtherCAT master and slave implementations. The PC-deployed EtherCAT master is based on open-source software: Linux, IgH EtherCAT master stack. The slave devices are implemented with market available components. The stability of the EtherCAT cycle time at 1 kHz and the slave devices events synchronization abilities are being investigated. The experimental results obtained from a designed setup with such an EtherCAT master controlling two slave devices developed showed the ability to synchronize events between the two slave devices within a sub 100 ns range. The stability of the proposed EtherCAT platform was proved with the measured 1000 us EtherCAT cycle time jitter of a few microseconds. It is possible to improve the performance of medical devices with computed tomography by implementing the EtherCAT industrial network. The proposed solution, based on open-source software and market-available components, provides a high level of production safety.