A Simple and Effective Method to Improve Pinnacle Auto-planning Based on Rectal Cancer

Background: Try to re-optimize the results of pinnacle Auto-planning (AP) and explore the feasibility of obtaining more dosiologically advantageous AP plans by reducing "experience-based optimization parameters". Methods: 35 rectal cancer cases with preoperative radiotherapy were selected and all plans are designed retrospectively with Pinnacle9.1 AP. Firstly we take the doctor's clinical prescription as a universal optimization parameters, get the first reference group CP; secondly we set the results of manual plans (MP) which were already used for clinical treatments as the optimization parameters, replacing the physicist's initial experience, get the second reference group IE; at last we reduce the results of MP by 15% as the optimization parameters , get the control group T. By keeping the other optimization conditions unchanged, we designed AP plans for all three groups. Wilcoxon rank sum tests were performed for CP-T and IE-T based on the dosiological parameters of the planning target volume(PTV) and organs at risk(OARs). Results: Dose distribution of all three groups was in a clinically acceptable range. The dose of OARs in T group was significantly lower than CP and IE,the differences were statistically significant. Conclusion: Experience-based AP plan has a space for re-optimization, and appropriately reducing the results of MP as optimization parameters is a simple and feasible way.