Comparative Analysis of Dose Variations in Tumor Volumes and Organs at Risk in IMRT Plans for Head-AndÃ¢ÂÂNeck, Pelvis and Brain Cancers with Varying Dose Calculation Grid Sizes
- *Corresponding Author:
- Pathak P
Chief medical Physicist, BIMR Hospitals, Radiation Oncology, Surya mandir road Gwalior
Madhya Pradesh 474004, India
E-mail: [email protected]
Received date: July 25, 2014; Accepted date: September 23, 2014; Published date: September 25, 2014
Citation: Pathak P, Guha S, Vidya V, Sourav M, Ashok S (2014) Comparative Analysis of Dose Variations in Tumor Volumes and Organs at Risk in IMRT Plans for Head-And–Neck, Pelvis and Brain Cancers with Varying Dose Calculation Grid Sizes. J Cancer Sci Ther 6:394-400. doi:10.4172/1948-5956.1000298
Copyright: © 2014 Pathak P, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Purpose: The aim of this study was to compare the plan results that were obtained by using different calculation grid sizes ranging from 3 mm to 10 mm, and the same dose calculation algorithm Pencil Beam (PB), in Intensity Modulated Radiotherapy (IMRT) for different treatment sites Head-And –Neck, Pelvis (Carcinoma Cervix) And Brain Cancers. Introduction: Ever since the advent and development of treatment planning systems, the uncertainty associated with calculation grid size has been an issue. Even to this day, with highly sophisticated 3D conformal and intensity-modulated radiation therapy (IMRT) treatment planning systems (TPS), dose uncertainty due to grid size is still a concern. Materials and methods: Twelve patients in which four patients of Head-And –Neck, Pelvis And Brain tumors respectively were considered for the study. IMRT Plans were generated for a 6,600cGy, 5,000cGy & 5,400cGy prescribed doses for Head-And –Neck, Pelvis and Brain tumors respectively using Oncentra v 4.3 TPS. For each patient, dose calculation with Pencil Beam (PB) algorithms using dose grid sizes of 3.0 mm, 5.0 mm, and 10.0 mm were performed. Results: The plans were evaluated as per the ICRU guidelines and dose constraints were maintained as per the Quantec guidelines. The dose differences for the varying grid sizes in Tumor Volumes and Organs at Risk were analyzed and tabulated. Conclusion: Overall, the effect of varying grid size on dose variation appears to be insignificant. However, 3 mm is recommended to ensure acceptable dose calculations, especially in high gradient regions.