Polymer gel dosimetry by nuclear Overhauser enhancement (NOE) magnetic resonance imaging. (31st July 2018)

• Record Type: Journal Article
• Authors: Quevedo, Ana; Luo, Guozhen; Galhardo, Edvaldo; Price, Michael; Nicolucci, Patrícia; Gore, John C; Zu, Zhongliang
• Is Part Of: Physics in medicine & biology. Volume 63:Number 15(2018:Aug.)
• Publication Date: 2018-07-31
• Subjects: polymer gel dosimetry -- nuclear overhauser enhancement (NOE) -- magnetization transfer (MT) -- chemical exchange saturation transfer (CEST) -- MAGIC gels; Biophysics -- Periodicals; Medical physics -- Periodicals; 610.153
• DOI: 10.1088/1361-6560/aad1bd
• Languages: English
• ISSNs: 0031-9155

Abstract

Abstract: The response to radiation of polymer gel dosimeters has previously been measured by magnetic resonance imaging (MRI) in terms of changes in the water transverse relaxation rate ( R 2w ) or magnetization transfer (MT) parameters. Here we report a new MRI approach, based on detecting nuclear Overhauser enhancement (NOE) mediated saturation transfer effects, which can also be used to detect radiation and measure dose distributions in MAGIC- f (Methacrylic and Ascorbic Acid and Gelatin Initiated by Copper Solution with formaldehyde) polymer gels. Results show that the NOE effects produced by low powered radiofrequency (RF) irradiation at specific frequencies offset from water may be quantified by appropriate measurements and over a useful range depend linearly on the radiation dose. The NOE effect likely arises from the polymerization of methacrylic acid monomers which become less mobile, facilitating dipolar through-space cross-relaxation and/or relayed magnetization exchange between polymer and water protons. Our study suggests a potential new MRI method for polymer gel dosimetry.