Journal of Isfahan Medical School

Journal of Isfahan Medical School

Evaluation of Calculation Errors of Treatment Planning System in Dose Distribution of Electron Beams inside the Lung in Three-Dimensional Conformal Radiation Therapy (3D-CRT)

Document Type : Original Article (s)

Authors
Mohammad Bagher Tavakoli 1
Hossein Taheri 2
Ali Akhavan 3
1 Professor, Department of Medical Physics, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
2 MSc Student, Department of Medical Physics, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
3 Assistance Professor, Department of Radiotherapy Oncology, Seyed Alshohada Hospital, Isfahan University of Medical Sciences, Isfahan, Iran
Abstract
Background: Calculation of dose distribution of electron beams within in homogeneities may be complex for some of treatment planning systems (TPS). The aim of this study was to investigate the calculation errors of targeted image-guided radiation therapy treatment planning systems (TiGRT TPS) for dose distribution of electron beams within lung.Methods: The computed tomography (CT) images of an anthropomorphic Rando phantom were imported on the treatment planning systems (TiGRT, Lina Tech, China). The direct 10 MeV electron plan was performed by the TiGRT treatment planning systems. According to the plan, the phantom was irradiated using 10 MeV electrons of Siemens Primus linac. Dose measurements were done using LiF (TLD-100) inside the lung of this phantom. Finally, the calculation of the treatment planning systems was compared to the dose measurements.Findings: The minimum (0.86%) and maximum (76.14%) calculation errors of the treatment planning systems were occurred on the chest wall-lung interface and at the end of lung, respectively.Conclusion: It considerably seems that the treatment planning systems may not be able to perform some of essential corrections for dose distribution of electrons within in homogeneities. In this study, the in- homogeneities included ribs and lung with low electron density. The calculation errors may be resulted from production of secondary beams and multi scattering of electrons (when the electrons incident to ribs), and also X-ray contamination of electron beams at the end of its path. Therefore, the calculation of the treatment planning systems for dose distribution of electron beams within the lung is not comfortable.
Keywords
Lung
Radiotherapy dosage
Treatment protocols
Phantoms
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Journal of Isfahan Medical School
Volume 35, Issue 440 - Serial Number 440
May and June 2017
Pages 900-904

  • Receive Date 03 November 2016
  • Accept Date 06 April 2022