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Treatment of the wrong body part due to incorrect setup is among the leading types of errors in radiotherapy. The purpose of this paper is to report an efficient automatic patient safety system (PSS) to prevent gross setup errors. The system consists of a pair of charge‐coupled device (CCD) cameras mounted in treatment room, a single infrared reflective marker (IRRM) affixed on patient or immobilization device, and a set of in‐house developed software. Patients are CT scanned with a CT BB placed over their surface close to intended treatment site. Coordinates of the CT BB relative to treatment isocenter are used as reference for tracking. The CT BB is replaced with an IRRM before treatment starts. PSS evaluates setup accuracy by comparing real‐time IRRM position with reference position. To automate system workflow, PSS synchronizes with the record‐and‐verify (R&V) system in real time and automatically loads in reference data for patient under treatment. Special IRRMs, which can permanently stick to patient face mask or body mold throughout the course of treatment, were designed to minimize therapist's workload. Accuracy of the system was examined on an anthropomorphic phantom with a designed end‐to‐end test. Its performance was also evaluated on head and neck as well as abdominalpelvic patients using cone‐beam CT (CBCT) as standard. The PSS system achieved a seamless clinic workflow by synchronizing with the R&V system. By permanently mounting specially designed IRRMs on patient immobilization devices, therapist intervention is eliminated or minimized. Overall results showed that the PSS system has sufficient accuracy to catch gross setup errors greater than 1 cm in real time. An efficient automatic PSS with sufficient accuracy has been developed to prevent gross setup errors in radiotherapy. The system can be applied to all treatment sites for independent positioning verification. It can be an ideal complement to complex image‐guidance systems due to its advantages of continuous tracking ability, no radiation dose, and fully automated clinic workflow.PACS number: 87.55.Qr

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Sensor nodes around monitoring area have various distances to the target node. Therefore, it is difficult to ensure security of broadcasting data transferred from a single wireless sensor node to base station. Multi-hop transmission of data between sensor nodes wastes network resource. In this case, a distributed data secure transmission scheme is proposed in a wireless sensor network. Data transmission is classified into two stages: constructing a collection of receiving nodes and selecting a unique forwarding node from this collection. These are implemented using analysis of relative movement distance between nodes and transfer time competitive mechanism. Besides, we have assumed a network model for distributed data secure transmission to improve efficiency of data transfer. This design includes secure model of node competition, data perception model, and anti-resistance model. Moreover, the security of competition transfer for nodes in wireless sensor network is evaluated. Finally, simulation proves that the proposed scheme has good performance in security and stability compared to similar schemes.

In this paper, a decoupling multivariable control strategy for linear time‐invariant (LTI) multi‐input/multi‐output (MIMO) systems is proposed. The strategy includes a multivariable disturbance observer (MDOB) and a decoupling controller. This MDOB is introduced to improve the system performances when the system encounters severe external disturbances. H2 optimal scheme is utilized to design the MDOB filter. The controller is developed based on an inverse control method, through which the design process can be simplified. Simulation results certify the effectiveness of the proposed control strategy.