Author: Sumanta Manna, Atul Mishra, Surendra Prasad Mishra, Kailash Kumar Mittal, Anoop Kumar Srivastava, Neha Yadav 👨🔬
Affiliation: Department of Radiation Oncology, Dr. Ram Manohar Lohia Institute of Medical Sciences, Department of radiation Oncology, Apollomedics Super Speciality Hospitals, Department of Radiation Oncology, Uttar Pradesh University of Medical Sciences, Department of Radiation Oncology, Kalyan Singh Super Specialty Cancer Institute 🌍
Purpose: This study aimed to assess the dosimetric performance of Volumetric Modulated Arc Therapy (VMAT), step-and-shoot Intensity-Modulated Radiation Therapy (ss-IMRT), and dynamic Intensity-Modulated Radiation Therapy (d-IMRT) for lung cancer treatment.
Methods: The study utilized Computed Tomography (CT) images of a Computerized Imaging Reference System (CIRS) phantom for treatment planning. Gross Tumor Volumes (GTVs) were delineated for central and peripheral lung tumors, and Planning Target Volumes (PTVs) were defined with a 5mm margin around the GTV. Treatment plans for VMAT and IMRT were generated using a 6-MV photon beam. Dose calculations were performed using the Monte Carlo (MC) and Pencil Beam (PB) algorithms.
Results: For PTV D95, d-IMRT showed better dose uniformity than ss-IMRT and provided comparable target coverage to VMAT for central tumors. ss-IMRT demonstrated superior coverage for peripheral tumors, while VMAT significantly improved dose homogeneity (p < 0.05) and reduced heart and lung doses (V5, V20) for peripheral targets. Furthermore, VMAT required significantly fewer monitor units compared to other techniques.
Conclusion: This study concluded that the MC algorithm outperformed the PB algorithm in dose calculation accuracy. VMAT demonstrated superior dosimetric outcomes and reduced monitor units compared to IMRT for both central and peripheral lung tumors, making it a preferred treatment approach. This investigation indicates that in the lung area, MC proves to be a more precise algorithm than PB.