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Crister Ceberg

Professor

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Modelling the dynamic dose response of an nMAG polymer gel dosimeter.

Författare

  • Sofie Ceberg
  • Martin Lepage
  • Sven Bäck
  • Helen Gustafsson
  • Crister Ceberg

Summary, in English

Gel dosimetry measures the absorbed radiation dose with high spatial resolution in 3D. However, recently published data show that the response of metacrylic-based polymer gels depends on the segmented delivery pattern, which could potentially be a considerable disadvantage for measurements of modern dynamic radiotherapy techniques. The aim of this study is to design a dynamic compartment model for the response of a gel dosimeter, exposed to an arbitrary irradiation pattern (segmented delivery and intensity modulation), in order to evaluate the associated effects on absorbed dose measurements. The model is based on the separation of the protons affecting the magnetic resonance signal (i.e. the R2 value) into six compartments, described by a set of differential equations. The model is used to calculate R2 values for a number of different segmented delivery patterns between 0-4 Gy over 1-33 fractions. Very good agreement is found between calculated and measured R2 values, with an average difference of 0.3 ± 1.1% (1 SD). The model is also used to predict the behaviour of a gel dosimeter exposed to irradiation according to typical IMRT, VMAT and respiratory gating scenarios. The calculated R2 values are approximately independent of the segmented delivery, given that the same total dose is delivered during the same total time. It is concluded that this study helps to improve the theoretical understanding of the dependence of metacrylic-based polymer gel response to segmented radiation delivery.

Avdelning/ar

  • Medicinsk strålningsfysik, Malmö
  • Medicinsk strålningsfysik, Lund

Publiceringsår

2012

Språk

Engelska

Sidor

4845-4853

Publikation/Tidskrift/Serie

Physics in Medicine and Biology

Volym

57

Issue

15

Dokumenttyp

Artikel i tidskrift

Förlag

IOP Publishing

Ämne

  • Radiology, Nuclear Medicine and Medical Imaging

Status

Published

Forskningsgrupp

  • Medical Radiation Physics, Malmö

ISBN/ISSN/Övrigt

  • ISSN: 1361-6560