Validation of motorized wedge effective isodose angle with a 2D array detector

Document Type: Original Paper

Authors

1 Radiotherapy and Oncology Senior Grade Lecturer Medical Physics Kasturba Medical College Manipal Academy of Higher Education Manipal India

2 Radiotherapy and Oncology M.Sc Medical Radiation Physics Student School of Allied Health Sciences Manipal Academy of Higher Education Manipal India

3 Radiotherapy and Oncology Assistant Professor in Medical Physics School of Allied Health Sciences Kasturba Medical College Manipal Academy of Higher Education Manipal 576104

4 Radiotherapy and Oncology Lecturer Medical Physics Kasturba Medical College Manipal Academy of Higher Education Manipal India

5 Radiotherapy and Oncology Assistant Professor in Medical Physics School of Allied Health Sciences Kasturba Medical College Manipal Academy of Higher Education Manipal India

6 Radiotherapy and Oncology Professor and Head Kasturba Medical College Manipal Academy of Higher Education Manipal India

Abstract

Introduction: Elekta Versa HD linear accelerator houses a universal wedge filter a single large, a physical wedge moves driven by motors viz., motorized wedge. It gives a nominal wedge isodose angle of 600 for the field size of 30×40 sq cm. Motorized wedge isodose distribution accomplished using a motorized wedge, which is a mix of open and wedge beam segments. Hence, carried out the validation of the planned wedge effective isodose angle in the present study.

Materials and Methods: We validated the planned wedge effective isodose angle for 150, 300, 450 and 600 with 6MV and 15MV for 10x10 sq cm and 20x20 sq cm field size using analytical formula against 2D array detector with a PTW Multi check software.

Results: The calculated and measured, planned wedge effective isodose angle in this work shows a maximum deviation from its pre-set angle (a nominal wedge angle) of 90 for a 6MV photon energy and 50 for 15MV for field size 10×10 sq cm and 20×20 sq cm.

Conclusion: We have validated the planned wedge effective isodose angle for a field size of 10x10sq cm, 20x20sq cm for 6MV and 15MV photon energies using an analytical method and 2D array detector with a reasonable agreement.

Keywords: Motorized wedge; Wedge angle; 2D Array Detectors; Isodose curves; Isodose angles.

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Articles in Press, Accepted Manuscript
Available Online from 30 October 2019
  • Receive Date: 05 March 2019
  • Revise Date: 25 July 2019
  • Accept Date: 30 October 2019