Iranian Journal of Medical Physics

Iranian Journal of Medical Physics

Evaluation of Dose Calculation Accuracy of Isogray Treatment Planning System in Craniospinal Radiotherapy

Document Type : Original Paper

Authors
Mohammad Taghi Bahreyni Toossi 1
Sara Momeni 2
Shokouhozaman Soleymanifard 3
Hamid Gholamhosseinian 4
1 Medical Physics Department, Medical Physics Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
2 M.S.c of Mashhad University of Medical Sciences, Medical Physics Research Center, Mashhad, Iran
3 Associate Professor of Medical Physics, Research Center of Medical Physics, Mashhad University of Medical Sciences, Mashhad, Iran
4 Medical Physics Dept, Faculty of Medicine, Mashhad University of Medical Sciences
10.22038/ijmp.2018.27332.1291
Abstract
Introduction: Craniospinal radiotherapy is a therapeutic technique for central nervous system (CNS) tumors, which requires meticulous attention to technique and dosimetry.Treatment planning system (TPS) is one of the main equipment in radiotherapy; therefore, the evaluation of its accuracy is essential for dose calculation. The present study evaluates the validity of Isogray TPS in craniospinal irradiation techniques.
Material and Methods: The computed tomography (CT) images of the brain and spine of the Rando phantom were acquired. Two techniques were designed. In technique 1, the whole CNS was irradiated with 6 MV photon beam. In technique 2, the brain and spine were irradiated with 6 MV photon and 18 MeV electron beam, respectively. The tumor and organs at risk doses were measured by thermoluminescent dosimeter (TLD). In addition, photon and electron dose measurements inside and outside the treatment field were accomplished using TLD, and then compared to the corresponding values calculated by TPS.
Results: According to the results, in both electron and photon beams, the differences between the doses calculated by TLD and TPS for the points inside the treatment field were less than 4% for 90% of the measurement points. However, for the points outside the treatment field borders, the differences ranged within 10-40%. These differences were indicative of the sufficient dosimetric accuracy of Isogray TPS.
Conclusion: The comparison of dosimetry results with those of TPS results revealed the accuracy of Isogray TPS. In both techniques, the maximum difference between the TLD- and TPS-measured doses was observed in the mandible.
Keywords
Craniospinal irradiation
CNS
TPS
Thermoluminescent Dosimetry
Subjects
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Iranian Journal of Medical Physics
Volume 15, Issue 4 - Serial Number 4
Autumn 2018
Pages 231-236

  • Receive Date 19 December 2017
  • Revise Date 21 February 2018
  • Accept Date 24 February 2018