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Comparison of Volumetric Modulated Arc Therapy and Intensity Modulated Radiotherapy Planning Techniques for Frontal and Temporal High-Grade Gliomas

C Della Biancia

P Godoy Scripes , C Della Biancia*, Memorial Sloan-Kettering Cancer Center, New York, NY


SU-I-GPD-T-497 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: To evaluate the potential benefits and limitations of the Volumetric Modulated Arc Therapy (VMAT) planning technique compared to Intensity Modulated Radiotherapy (IMRT) for patients with frontal and temporal high-grade gliomas.

Methods: Ten patients were divided into two groups: 1) planning target volumes (PTVs) nearby or overlapping organs at risk (OARs) and 2) PTVs distant to OARs. All patients were planned with IMRT and VMAT techniques without constraining the normal brain tissue and using the following planning objectives: 100% isodose covers 98% of PTV while respecting OAR and hot spot dose constraints. For VMAT only, two plans were created: with and without mean dose constraint to the normal brain in order to further investigate whether VMAT would potentially increase the dose to the surrounding normal tissue. The prescription dose was 60Gy in 30 fractions. Treatment plans were compared using dose-volume histogram (DVH). For target coverage, the comparison parameters included maximum dose, Conformity Index (CI) and Homogeneity Index (HI).

Results: Target coverage, homogeneity and conformality were equivalent among techniques, being IMRT slightly better than VMAT. For all cases and planning techniques the OARs constraints were respected. Normal brain mean dose was 19.82±4.30Gy (IMRT) and 20.74±4.61Gy (VMAT) for patients in group 1, and 24.83±8.46Gy (IMRT) and 30.84±18.60Gy (VMAT) for patients in group 2. After constraining the normal brain for VMAT cases, the mean dose was 19.42±4.24Gy and 23.77±7.70Gy for each group of patients (PTVs nearby/distant to OARs).

Conclusion: IMRT seemed to be a preferred technique. VMAT could also be the technique of choice considering its benefits of reducing treatment delivery duration; however normal brain tissue and other OARs should be constrained during the optimization process.

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