Application of statistical process control method in radiotherapy patient plans quality assurance
Objective Statistical process control(SPC)method was used to establish tolerance limits and action limits based on EPID for gamma analysis using 3%/2mm and 3%/3mm criterias at different sites and different radiotherapy techniques.Methods 129 IMRT plans and 89 VMAT plans including head and neck,chest,abdomen and other sites were selected for dose verification by EPID,The tolerance limits and action limits were calculated based on the gamma passing rate results of the first 20 patients plans for each site.The individual control charts were drawn to continuously monitor the gamma passing rate of all plans in different sites under different measurement criterias.Results Under the criteria of 3%/3mm,the tolerance limits of each site of the two techniques were greater than 97%,and the action limits were close to97%.The criteria of 3%/2mm,the tolerance limits of each site were greater than94%,and the action limist were greater than 92%.Conclusion SPC can effectively monitor and improve the quality control process of patient plans and setting individual tolerance limits and action limits in different sites,different radiotherapy techniques and different measurement criterias,it can reduce the risk of mistakes and lower the occurrence of clinical accidents.
Statistical process control methodPatient-specific quality assuranceGamma passing rateTolerance limitsAction limits