Reliability Assessment Of The Pulse Modulator Of Medical Linear Accelerators

With the increasing incidence of cancer,the self-developed radiotherapy equipment in China is also booming.Radiotherapy equipment requires extremely high reliability,which is one of the key factors that foreign radiotherapy equipment occupies most of the domestic market.In order to improve the competitiveness of domestic radiotherapy equipment and ensure the safety of patients and medical workers,it is imperative to improve the reliability of domestic radiotherapy equipment.Medical linear accelerators are the most widely used radiotherapy equipment.The pulse modulator is one of the core components of the medical linear accelerator,which is an electronic device that provides a suitable pulse voltage for the microwave source.It is a key device to ensure the quality of the pulse and the quality of the accelerator treatment.Physics-of-failure is a common method for reliability assessment of electronic products.It is a method that analyzes the failure mode and failure mechanism of the product to determine the weak point of the product and the corresponding failure physics models of the fault.And after determining the required parameters by means of stress simulation analysis,the life of the weak point can be calculated.Physics-of-failure is a highly accurate reliability assessment method when the life data is insufficient.In this paper,after using the Physics-of-failure and finite element analysis to determine the life of the weak point,the Monte Carlo simulation is used to evaluate the reliability of the pulse modulator.The research of this paper can be used as reference for the reliability research of the domestic pulse modulator and the medical linear accelerator.The research or this thesis can be concluded as follows:(1)Combining with the product information of the pulse modulator,the structure and function of the pulse modulator are analyzed,the structure and function hierarchical block diagram are drawn,and the common fault causes of the pulse modulator are analyzed according to the fault statistics.(2)According to the fault reason of pulse modulator and the opinion of manufacturer engineer,the key fault mechanism,potential fault point and corresponding Physics-of-failure model of pulse modulator are determined.(3)According to the determined fault physical model,the finite element simulation analysis of the pulse modulator is carried out.Then obtain temperature distribution and the through-hole strain of the pulse modulator,and analyze the life distribution law of each fault point of the pulse modulator.(4)The reliability model of the pulse modulator is established.The reliability model of the pulse modulator is used to evaluate the reliability of the pulse modulator by Monte Carlo simulation combined with the life distribution law of the fault point.The life distribution law of the pulse modulator is analyzed and the expected life of the modulator is calculated.