Calculations of Linac Photon Dose Distributions in Homogeneous Phantom Using Spline

Document Type: Original Paper

Authors

1 Medical Physics Research Center, Medical Physics Department, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran

2 Medical Physics Research Center, Medical Physics Department, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran Imam Reza Hospital, Mashhad University of Medical Sciences, Mashhad, Iran

3 Department of Computer Engineering, Ferdowsi University of Mashhad, Mashhad,

Abstract

Introduction
Relative dose computation is a necessary step in radiation treatment planning. Therefore, finding an approach that is both fast and accurate seems to be necessary. The purpose of this work was to investigate the feasibility of natural cubic spline to reconstruct dose maps for linear accelerator radiation treatment fields in comparison with those of the simulation.
Materials and Methods
A natural cubic spline algorithm was used to reproduce dose calculations of linac radiation treatment fields resulting from GEANT4 application for tomographic emission (GATE) simulation. The spline algorithm was used to compute percent depth dose of radiation therapy fields for 6 MV X-rays, which were calculated by simulation of Elekta Compact Linac. It reconstructed 2-dimensional dose maps and created isodose distributions. This dose maps were evaluated and compared with the simulation, where the γ -index was used.
Results
A good agreement was found between the doses calculated from the simulation and the spline. In particular, an average γ-index passing rate of 0.24 was obtained for sample percent depth dose distributions, and an average γ -index passing rate of 0.20 was observed for sample dose profiles.
Conclusion
Natural cubic spline has been established to calculate dose maps from field characteristics. The feasibility and possibility of natural cubic spline to calculate dose maps for linac radiation therapy fields in a homogeneous phantom has been demonstrated.

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Volume 10, Issue 2
September and October 2013
Pages 133-138
  • Receive Date: 02 July 2013
  • Revise Date: 28 January 2014
  • Accept Date: 02 November 2013