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MO_8_2668 - Helical Tomotherapy for Whole- Brain Irradiation With Integrated Boost to Multiple Brain Metastases: Dosimetric Analysis and Clinical Outcomes

Monday, October 22
10:45 AM - 12:15 PM
Location: Innovation Hub, Exhibit Hall 3

Helical Tomotherapy for Whole- Brain Irradiation With Integrated Boost to Multiple Brain Metastases: Dosimetric Analysis and Clinical Outcomes
Y. Ma1, J. Xiao2, N. Bi3, Y. Xu2, Y. Tian2, H. Zhang2, Y. Zhang2, Q. Liu2, L. Deng4, W. Wang5, R. Zhao2, S. Yang2, and Y. X. Li6; 1National Cancer Canter/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, 2National Cancer Center/ Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, 3National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, 4Department of Radiation Oncology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, 5Department of Radiation Oncology, National Cancer Center / Cancer Institute & Hospital, Chinese Academic of Medical Sciences, Beijing, China, 6State Key Laboratory of Molecular Oncology and Department of Radiation Oncology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College (PUMC), Beijing, China

Purpose/Objective(s): A retrospective study was conducted to analysis the dose distribution characteristics, and evaluate the feasibility and toxicities of Tomotherapy for whole brain irradiation (WBRT) with simultaneously integrated boost (SIB) to multiple brain metastases (BMs).

Materials/Methods: From 2014 to 2017, 43 patients with three or more BMs were analyzed. WBRT and SIB were delivered with 40 Gy and 60 Gy in 20 fractions by Tomotherapy. Patients were reexamined by magnetic resonance imaging (MRI) during treatment. The radiation field would be shrunk if the gross target volume (GTV) reduced. Target Coverage (TC), conformation number (CN), prescription isodose/ target volume ratio (PITV) and homogeneity index (HI) was accessed. Clinical endpoints included local recurrence- free survival (LRFS), intracranial progresstion- free survival (IPFS), progression- free survival (PFS), overall survival (OS) and toxicities.

Results: The median lesion number was 6 (3- 36) and median total volume of GTV was 8.74 cc (0.37- 120.32 cc). Median GTV Dmean was 63.1 Gy (50.2- 72.58 Gy). Mean± standard deviation for GTV amounted to TC= 0.96±0.028、CN= 0.51±0.164、PITV= 2.09±1.245, and HI= 0.12±0.066, respectively. TC and HI for whole brain were 0.95±0.033 and 0.43±0.161, respectively. 25.6% of patients got replanned and the mean dose of normal tissue reduced by 0.7- 2.0 Gy. One- year LRFS, IPFS, PFS and OS were 95.7%、79.9%、39.4% and 85.6%, respectively. There were no grade 3- 5 toxicities.

Conclusion: Tomotherapy for WBRT and SIB showed excellent conformity and homogeneity,and it’s efficient and safe for patients with multiple BMs. Lesions that got shrunk during treatment should be replanned to reduce the dose of normal tissue.

Author Disclosure: Y. Ma: None. J. Xiao: None. H. Zhang: None. Q. Liu: None. Y. Li: Employee; Cancer Hospital & Institute, CAMS & PUMC. Chairman, Department of Nuclear Medicine; Cancer Hospital & Institute, CAMS & PUMC. Chairman, Department of Radiation Oncology; Cancer Hospital & Institute, CAMS & PUMC.

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