Iranian Journal of Medical Physics

Iranian Journal of Medical Physics

Dosimetric evaluation of IMRT Step and Shoot/ Sliding and Window (SS / SW) and VMAT Treatment Plans for Nasopharyngeal Cancer

Document Type : Original Paper

Authors
Rachid Errifai 1
Youssef Bouzekraoui 2
FARIDA BENTAYEB 1
1 Department of Physics, LPHE, Modeling and Simulations, Faculty of Science, Mohammed V University, Rabat, Morocco
2 Hassan First University of Settat, High Institute of Health Sciences, Laboratory of Sciences and Health Technologies, Settat, Morocco
10.22038/ijmp.2021.53524.1879
Abstract
Introduction: Radiotherapy of Oto-Rhino-Laryngology (ORL) sphere is difficult due to complex geometries and very sensitive organs around the target volume. This weapon has benefited from the advances of the Volumetric Modulated Arc Therapy (VMAT) technique that combines the advantages of dynamic arc therapy techniques with those of Conformal Radiotherapy with Intensity Modulated (CRIM) by stationary beams.
Material and Methods: The treatment plans of 10 patients were compared and treated with Intensity Modulated Radiation Therapy (IMRT) Step and Shoot (SS), Sliding window (SW), and VMAT (6MV X-ray beam). Three target volumes were used: PTVث Gy, PTV 63 Gy, and PTV 56 Gy. The organs at risk were the spinal cord, the brainstem, the parotid gland. The dose was delivered once a day, five days a week and in 35 sessions in Simultaneous Integrated Boost (SIB).
Results: The SS technique permitted better parotid sparing, inducting thus to limiting late complications such as xerostomia. The VMAT technique led to better protection of the brainstem by reducing about 6 Gy while for the spinal cord the doses received were almost equal. There was no statistically significant difference between the different techniques.
Conclusion: The results confirm the conformational capacities of these innovative techniques, from a dosimetric and above all clinical point of view as well as their ability to cover the target volumes while largely respecting the constraints on organs at risk.
Keywords
Nasopharyngeal Cancer
Radiotherapy
IMRT
VMAT
Dose
Subjects
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Iranian Journal of Medical Physics
Volume 19, Issue 1
January and February 2022
Pages 31-42

  • Receive Date 14 November 2020
  • Revise Date 03 May 2021
  • Accept Date 13 May 2021