Gel-based radiation dosimetry using quantitative MRI

Y. De Deene*

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract

By dissolving radiation sensitive chemicals into a gel matrix, a three-dimensional (3D) radiation dosimeter can be manufactured. These dosimeters can be used as anthropomorphic shape radiation dosimeters for dose verification of modern radiotherapy treatments. A first class of 3D radiation dosimeters is Fricke gel dosimeters, where the active radiation sensitive component is a bivalent cation such as the ferrous ion (Fe2+), which is oxidized upon irradiation. The oxidation reaction results in a change in the spin-lattice (R1) and spin-spin relaxation rates (R2), which can be mapped with MRI. A second class of 3D radiation dosimeters is polymer gel dosimeters, which are based on vinyl or acrylate monomers that are dissolved in a gelatin or agarose gel. When exposed to radiation, a dose dependent radical polymerization occurs. The amount of entangled or radiation induced grafted polymer is dose dependent and can be read out by use of MRI, optical scanning techniques or X-ray CT. It is mainly the spin-spin relaxation rate (R2) that is affected in polymer gel dosimeters. A third class is based on the radiation induced conversion of a coloured dye such as leuco-malachite green in the presence of a radical initiator. The coloured dye and radical initiator are mostly hydrophobic and are suspended in a gel matrix as micelles. These 3D dosimeters do not result in significant changes in NMR properties, but can be read out optically.

Original languageEnglish
Title of host publicationNMR and MRI of gels
EditorsYves De Deene
Place of PublicationLondon
PublisherRoyal Society of Chemistry
Chapter9
Pages275-357
Number of pages83
ISBN (Electronic)9781788013178, 9781788019200
ISBN (Print)9781788011525
Publication statusPublished - 2020

Publication series

NameNew Developments in NMR
PublisherRoyal Society of Chemistry
Number23
ISSN (Print)2044-253X
ISSN (Electronic)2044-2548

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