Validation of dose painting of lung tumours using alanine/EPR dosimetry

Ingerid Skjei Knudtsen*, Jorund Graadal Svestad, Erlend Peter Skaug Sande, Bernt Louni Rekstad, Jan Rodal, Wouter van Elmpt, Michel Öllers, Eli Olaug Hole, Eirik Malinen

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

5 Citations (Web of Science)

Abstract

Biologic image guided radiotherapy (RT) with escalated doses to tumour sub volumes challenges today's RT dose planning and delivery systems. In this phantom study, we verify the capability of a clinical dose planning and delivery system to deliver an F-18-FDG-PET based dose painted treatment plan to a lung tumour. Furthermore, we estimate the uncertainties of the dose painted treatment compared to conventional RT plans. An anthropomorphic thorax phantom of polystyrene and polyurethane was constructed based on CT images of a lung cancer patient. 101 EPR/alanine dosimeters were placed in separate cavities within the phantom. IMRT and VMAT plans were generated in Eclipse (version 10.0, Analytical Anisotropic Algorithm version 10.2.28, Varian Medical Systems, Inc.) for 6 and 15 MV photons, based on F-18-FDG-PET/CT images of the patient. A boost dose of 3.8 Gy/fraction was given to the F-18-FDG-avid region (biological planning volume; BTV), whereas 3.1 Gy/fraction was planned to the planning target volume (PTV, excluding the BTV). For the homogenous plans, 3.2 Gy/fraction was given to the PTV. Irradiation of the phantom was carried out at a Varian Trilogy linear accelerator (Varian Medical Systems, Inc.). Uncertainties involved in treatment planning and delivery were estimated from portal dosimetry gamma evalutation. Measured and calculated doses were compared by Bland-Altmann analysis. For all treatment plans, all dose-volume objectives could be achieved in the treatment planning system. The mean absolute differences between calculated and measured doses were small (
Original languageEnglish
Pages (from-to)2243-2254
JournalPhysics in Medicine and Biology
Volume61
Issue number6
DOIs
Publication statusPublished - 21 Mar 2016

Keywords

  • radiotherapy
  • lung cancer
  • phantom
  • IMRT
  • VMAT
  • PET
  • functional imaging

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