Room: Exhibit Hall
Purpose: To investigate the performance of Auto-Planning intensity modulated radiation therapy(IMRT) plan for patients with central lung cancer, and whether Auto-Planning improve the quality of IMRT plans.
Methods: Thirty patients treated with IMRT for central lung cancer were re-planned with PinnacleÂ³ Auto-Planning module. The target dose distribution, organs at risk(OAR) sparing, the dose distribution of normal tissues in the ring within 3cm distance outside of the target and the low-dose region outside of this ring, monitor units(MU) and the efficiency of MU were evaluated. Wilcoxon signed rank test was used to check for significant differences (p<0.05) between datasets.
Results: The target homogeneity in Auto-Planning was significantly better than the manual plan, but manual plans significantly improved conformability. Auto-Planning had lower lung of Vâ‚…, Vâ‚?â‚€, Vâ‚?â‚ƒ, Vâ‚‚â‚€, Vâ‚ƒâ‚€, Vâ‚„â‚€, MLD(p<0.01); Spinal cord of maximum dose(p<0.01); and heart of Vâ‚ƒâ‚€(p<0.01); no significantly different in heart of Vâ‚„â‚€ as compared with manual plans(p=0.088). The mean dose and Dâ‚‚ of the ring 5mm away from target were reduced with Auto-Planning, however the mean dose, Dâ‚‚ and Dâ‚… in the rings between 1cm and 3cm outside the target were significantly increased. In 11 plans, 6000cGy hot spots appeared in the low-dose region for Auto-Planning, although Auto-Planning reduce 4000cGy dose volume in this region, the hot spots 5400cGy dose volume was significantly increased as compared with manual plans. MUs were added by 5.3% in Auto-Planning, the MU delivery efficiency of the Auto-Planning (39.3 cmÂ²/MU) was lower than that of the manual plans (46.1 cmÂ²/MU).
Conclusion: Auto-planning achieved highly quality consistent and OAR spring, but for some plans, the dose in the rings between 1cm and 3cm outside the target increased in Auto-planning, and hot spots appeared in the low-dose region. It was recommended to be combined with further manual processing, especially hot spot processing.
Funding Support, Disclosures, and Conflict of Interest: Funding Support: This work was supported by Shanghai Hospital Development Center "Three-year plan of action for promoting clinical skills and clinical innovation in municipal hospitals" (No.16CR3056A).