title: Evaluation of the dose distribution gradient in the close vicinity of brachytherapy seeds using electron paramagnetic resonance imaging.
abstract: Electron paramagnetic resonance (EPR) spectroscopy has been successfully employed to determine radiation dose using alanine. The EPR signal intensity reflects the number of stable free radicals produced, and provides a quantitative measurement of the absorbed dose. The aim of the present study was to explore whether this principle can be extended to provide information on spatial dose distribution using EPR imaging (EPRI). Lithium formate was selected because irradiation induces a single EPR line, a characteristic that is particularly convenient for imaging purposes. (125)I-brachytherapy seeds were inserted in tablets made of lithium formate. Images were acquired at 1.1 GHz. Monte Carlo (MC) calculations were used for comparison. The dose gradient can be determined using two-dimensional (2D) EPR images. Quantitative data correlated with the dose estimated by the MC simulations, although differences were observed. This study provides a first proof-of-concept that EPRI can be used to estimate the gradient dose distribution in phantoms after irradiation.
authors.affiliation: Biomedical Magnetic Resonance Unit, Université catholique de Louvain, Brussels, Belgium.
authors.forename: Emilia S
authors.initials: ES
authors.lastname: Vanea
authors.forename: Philippe
authors.initials: P
authors.lastname: Levêque
authors.forename: Fadi
authors.initials: F
authors.lastname: Abboud
authors.forename: Anne
authors.initials: A
authors.lastname: Bol
authors.forename: Jean Marc
authors.initials: JM
authors.lastname: Denis
authors.forename: Natallia
authors.initials: N
authors.lastname: Kolbun
authors.forename: Stefaan
authors.initials: S
authors.lastname: Vynckier
authors.forename: Bernard
authors.initials: B
authors.lastname: Gallez
mesh_terms: D000465:Algorithms; D001918:Brachytherapy / Q000295:instrumentation* / Q000379:methods*; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity