The Research And Implementation Of Cervical Intracavitary Brachytherapy Quality Assurance Procedure

Objective:Intracavity brachytherapy is a key step in cervical cancer radiotherapy and play an irreplaceable role.To ensure patients,staff,publics and department radiation safety and improve the implementation of the treatment process,keep implementation of physical dose accurately,it is necessary to establish the perfect quality control procedures for cervical cancer treatment process from close range,according to the reasonable frequency and the key factors which is needed for testing.Methods:Well-type ionization chamber,high-definition cameras,on board imaging system,two-dimensional ion chamber matrix and other QA tools just like EBT film are used to confirm the system safety,physical parameters,dose distribution measurement and treatment planning system,solve for many problems involved in the process of clinical application,such as equipment function test,source activity,the positioning accuracy dwell time precision,performance of the treatment planning system,evaluation of dose distributions,and other key links of cervical cancer brachytherapy process,to develop the effective method of testing and evaluating the whole process,and to implement the necessary of quality assurance and quality control.Results:The focus of security system testing is interruption and continue the plan,pulled back the source successfully during power failure.Among physical parameters,Source of nominal activity deviation is usually less than 3%.Transmission system confirmation,source positioning accuracy measurement,applicator geometry accuracy measurement is less than 1 mm,dwell time accuracy<0.5 s.The applicator reconstruction precision of planning system get worse with the increase of the length and Angle.Dose distribution test is for the whole process validation,using gamma evaluation method and analysis of the plane dose distribution,with 3 mm/3%standards,the passing rate is more than 95%.Conclusion:The equipment quality control work can known the daily status,clarify equipment performance and the source activity,positioning,timer,applicator,planning system and other related quality control aim,avoiding false irradiation and radiation safety accidents.According to the process of quality control system for cervical cancer brachytherapy,we are able to refine the work steps,improve the work efficiency,ensure the accurate implementation of the brachytherapy treatment.