ESTRO 2021 Abstract Book

S359

ESTRO 2021

Conclusion Coplanar VMAT with 2-3 additional computer-selected non-coplanar beams could substantially reduce parotid mean dose in nasopharyngeal cancer patients. Reductions were highly patient dependent. Automated planning can be used to find for each patient an optimal trade-off between dosimetric gain and increase in delivery time. OC-0472 Automated and clinical-criteria-driven optimal planning: clinical experience with over 3400 patients L. Hong 1 , M. Zarepisheh 1 , Y. Zhou 1 , Q. Huang 1 , G. Jhanwar 1 , J. Yang 1,2 , H. Pham 1 , L. Cervino 1 , J. Yamada 2 , J. Deasy 1 1 Memorial Sloan Kettering Cancer Center, Medical Physics, New York, USA; 2 Memorial Sloan Kettering Cancer Center, Radiation Oncology, New York, USA Purpose or Objective To present our clinical experience with an automated approach to IMRT treatment planning using expedited constrained hierarchical optimization (ECHO) to improve clinical workflow, planning efficiency, and plan After contouring, a template using multiple IMRT fields was created and sent to ECHO through the Eclipse® application program interface (API) plug-in. Institutional clinical criteria, including maximum and mean doses plus dose volume metrics, were separated into 2 categories: limits and guidelines. These clinical criteria were directly employed as template ECHO input parameters to derive appropriate objective functions and constraints. ECHO optimization strictly enforced limits as constraints and optimized the guidelines as much as possible using objective functions. The optimal fluence map generated by ECHO was imported automatically into Eclipse for leaf sequencing and final dose calculation. Upon ECHO completion, the planner received an email indicating the plan was ready for review. The email also includes a plan quality summary report. The plan was accepted by the planner if all clinical criteria were met, otherwise a limited number of parameters could be adjusted prior to another run with ECHO. Results We have established a process to develop and implement ECHO to the clinic. For each disease site, a template based on the established clinical criteria (limit and guidelines) was created and ECHO only required limited representative training patient data to fine tune few optimization parameters (e.g., dose fall-off criteria, slip factors). After training, the same parameters were then used to validation study of slightly more plans with a few prescription schemes and corresponding clinical criteria and compared with manual plans. Those parameter templates were then clinically implemented to plan that disease site with widely different prescription scheme and can easily adapt to changing clinical practice. Table 1 illustrates details of the process. quality and consistency. Materials and Methods

From 4/2017 to 2/2021, 3401 patients underwent radiotherapy using 3896 ECHO produced plans. Figure below