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An Integrate Strategy: Combination of Biological and Dose-Volume Constraints in IMRT Optimization

Z Feng

Z Feng1*, C Tao2 , J Zhu2 , J Chen2 , G Yu1 , S Qin1 , Y Yin2 , (1) Shandong Normal University, Jinan, Shandong, (2) Shandong Cancer Hospital Affiliated to Shandong University, Jinan, Shandong,


SU-I-GPD-T-319 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: An integrate optimized strategy (INO) for intensity-modulated radiation therapy (IMRT) was proposed by combing biological constraints and dose volume constraints for cervical carcinoma.

Methods: Twenty advanced stage cervical carcinoma patients were selected for verifying this strategy. INO included two basic constraints: physical constraints and biological constraints. The physical constraints were only applied for planning target volume (PTV). Otherwise, the biological constraints were only used to organ at risks (OARs). Two biological models, namely NTCP LKB model, were implemented in these study for two main OARs, rectum (Late effects, grade 3) and bladder (Late effects, grade 3), respectively. Furthermore, for each patient, the conventional physical optimized (PHO) plan was created with same physical constraints for PTV. And combing TCP, EUD and those two NTCP models, the corresponding biological optimized (BIO) plan was also generated. For evaluating INO plans quality, each INO plan was compared with their corresponding PHO and BIO by both physical endpoints and NTCP values.

Results: INO plans produced better PTV conformity and homogeneity than BIO plans, according to endpoints with significant differences, such as V95, D98, CI and HI (INO plans: V95 = 98.31, D98 = 54.18Gy, CI = 0.76, HI = 0.09; BIO plans: V95 = 96.79, D98 = 53.42Gy, CI = 0.71, HI = 0.10). In addition, the NTCP values of rectum and bladder generated by INO plans (NTCP = 0.14 and 0.16 for rectum and bladder, respectively) were lower than PHO plans (NTCP = 0.19 and 0.18 for rectum and bladder, respectively) with significant differences.

Conclusion: To some extent, the INO plans could improve PTV coverage, conformity and homogeneity than BIO plans, as well as reduce NTCP values of rectum and bladder compared with PHO plans.

Funding Support, Disclosures, and Conflict of Interest: This research was partially funded by the National Natural Science Foundation of China (NO.61471226), Natural Science Foundation for Distinguished Young Scholars of Shandong Province (NO. JQ201516).We also thank the supporting of Taishan scholar project of Shandong Province.

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