SU-F-T-357: Dosimetric Comparison of Automatic IMRT Planning and Manual IMRT Plan for Head and Neck Cancer

Authors


Abstract

Purpose:

The purpose of this study is to compare dosimetric differences of Auto-planning and manual IMRT plan and investigate the feasibility and efficiency of the Auto-planning in the nasopharyngeal carcinoma (NPC).

Methods:

Ten patients with NPC treated were enrolled in this study. Two IMRT plans were generated for each patient: manually optimized clinical plan and the automatically optimized plan using the Pinnacle Auto-planning (Auto plan). All the plan parameters such as gantry angle, the maximum number of iterations, the maximum number of control points, minimum segment MU and area are same, except the optimization method. For each IMRT plan, dose-volume histograms (DVHs) were calculated for target volumes and organs at risk (OARs). DVHs of targets and OARs were compared. The endpoints of targets were the D2 (Dx means dose to x% of the target volume), D98, V95 (Vx means percent of volume that received x% of dose prescription) and V100. The endpoints of OARs were Dmax for spinal cord and brainstem. The parotid glands were evaluated by V30.

Results:

For PTV66, PTV60, the dose coverage from both plans were met the clinical requirements. For the PTV66 (PTV60), the mean and standard deviation of V95 were 99.85±0.16 (99.86±0.55), 99.93±0.10 (99.02±0.49) and V100 were 97.84±1.58 (96.59±1.44), 98.56±1.06 (96.94±1.02) for Auto-planning and manually plan, respectively. For sensitive structures the doses of spinal cord and brainstem were not exceed the limitation. The V30 of the parotid glands were similar in two planning methods. The DVH of Auto plan and manual IMRT plan were accepted by clinical requirement, but the dose distribution of Auto-planning were not met the clinical requirement.

Conclusion:

According to the preliminary result of this study, The Auto-planning can get feasible DVH to the early stage NPC. However, manual adjustments are still required to get the finally acceptable plans.

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