Application of Volumetric Modulated Arc Therapy and Simultaneous Integrated Boost Techniques to Prepare “Safe Margin” in the Rabbit VX2 Limb Tumor Model
Chong-Wen Wang, Yang Zhou, Jing-Ping Bai, Hao Liu, Yan Liu, Guang-Li Shi, Jiao-Jiao Ding, Dong-Hui Ma, Wen-Ting Li, Peng-Ming Xie, Yue Yan
Department of Bone and Soft Tissue, The Affiliated Tumor Hospital of Xinjiang Medical University, Urumqi, Xinjiang, China (mainland)
Med Sci Monit 2015; 21:2397-2405
In this study, we aimed to establish the rabbit VX2 limb tumor model, and then prepare a “necrotic zone” as a safe margin by volumetric modulated arc therapy and simultaneous integrated boost (VMAT-SIB) technique applied in the areas where the tumor is located adjacent to the bone (GTVboost area).
MATERIAL AND METHODS: Rabbits in the control group (n=10) were not treated, while those in the test group (n=10) were treated with the SIB schedule delivering a dose of 40Gy, 35Gy, 30Gy, and 25Gy to the GTVboost, GTV (gross tumor volume), CTV (clinical target volume), and PTV (planning target volume) in 10 fractions. Magnetic resonance diffusion-weighted imaging (MRDWI), 3-dimensional power Doppler angiography (3D-PDA), and histological changes were observed after radiotherapy.
RESULTS: After radiotherapy, the two groups showed a significant difference in the GTVboost area. In the test group, the tumor necrosis showed a significantly low signal in DWI and high signal in apparent diffusion coefficient (ADC) maps. The 3D-PDA observation showed that tumor vascular structures decreased significantly. Histological analysis demonstrated that a necrotic zone could be generated in the GTVboost area, and microscopic examination observed cell necrosis and fibroplasia.
CONCLUSIONS: This studies demonstrated the feasibility of using VMAT-SIB technique in the rabbit VX2 limb tumor model. The formation of a necrotic zone can be effectively defined as safe margin in the GTVboost area. showing potential clinical applicability.
Keywords: Extremities, Diffusion Magnetic Resonance Imaging, Animals, Angiography, Imaging, Three-Dimensional, Magnetic Resonance Imaging, Necrosis, Rabbits, Radiotherapy Dosage, Radiotherapy, Intensity-Modulated - methods, Sarcoma, Experimental - radiotherapy, Soft Tissue Neoplasms - radiotherapy, Ultrasonography, Doppler