Magnetic resonance imaging of radiation dose distribution: a proposed dosimeter
University of New Brunswick
Paramagnetic metal ions have recently been proposed as NMR contrast agents for use in radiation dosimetry. Most work in this area has concentrated on altering T1 by changing the electronic structure, and thus the electron spin relaxation time, τ1e, of the paramagnetic metal under the action of radiation. An alternative approach will be discussed, that of incorporating the metal ion into a polymer formed under the action of radiation; this increases its rotational correlation time, τR, which also decreases T1. In a water-based gel matrix, formation of the polymer provides a contrast mechanism which is spatially-resolved and constitutes a suitable radiation dosimeter. Several gel/metal ion combinations have been studied in order to characterize the process; one such combination involves the use of nickel as the paramagnetic ion. Attaching it to an acrylic monomer, in a 30% acrylamide solution, changed T1 by a factor of four when polymerization was induced. A field-dependence study of the gel/metal ion combinations has also been conducted.