Application of automatic generation of dose limited structures in intensity modulated radiation therapy planning for nasopharyngeal carcinoma

Objective The contour of dose limited structures (DLSs) are needed for intensity modulated radiation therapy (IMRT) design for nasopharyngeal carcinoma (NPC), while using conventional method will cost lots of time of medical physicist. In this study, workflow was compiled and DLSs were automatically generated based on MIM software (V6.5) for IMRT planning optimization of NPC, in order to compare the time difference of workflow method with that of conventional method. Methods According to the unified requirements of IMRT planning optimization, the DLSs of 10 NPC cases with different tumor node metastasis (TNM) stages were contoured by three medical physicists using two methods. One was delineating with contour tools of Eclipse (V11.0) treatment planning system (TPS) for each procession one by one, and the other was contouring with MIM software to design and compile workflow for batch procession. The effect of workflow automatic processing was observed and the time-consumption was compared between the two methods. Results The workflow method could automatically generate 4 types of 28 DLSs including out-planning target volumes (PTVs), in-PTVs, organs at risk (OARs) and other subsidiary structures. The contour time-consumption of the workflow method was much lower than that of conventional method, with an average of 90.5% and up to 92.8% of time could be saved (t=32.14~61.59, P<0.05). Conclusions The workflow compiled with MIM platform can automatically generate batch DLSs, and effectively reduce the time of contour, thus improving work efficiency of medical physicist in IMRT planning for NPC. Key words: Nasopharyngeal carcinoma; Intensity modulated radiation therapy; Workflow; Batch procession; Dose limited structures