Visualization of free radical reactions in an aqueous sample irradiated by 290 MeV carbon beam

• Published in: Magnetic resonance in medicine Vol. 61; no. 5; pp. 1033 - 1039
• Main Authors: Matsumoto, Ken-ichiro, Nagata, Katsura, Yamamoto, Haruhiko, Endo, Kazutoyo, Anzai, Kazunori, Aoki, Ichio
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01-05-2009
• Subjects: Carbon; Electron Spin Resonance Spectroscopy - methods; EPR; Free Radicals - analysis; Free Radicals - chemistry; Free Radicals - radiation effects; Heavy Ions; Heavy-ion cancer therapy; MRI; oxygen effect; radiation modifier; reactive oxygen species
• ISSN: 0740-3194; 1522-2594
• DOI: 10.1002/mrm.21958

The detection of free radical reactions in a gelatin sample irradiated by a heavy‐ion beam was tested using electron paramagnetic resonance (EPR) spectroscopic and MRI methods. Geometry and the amount of free radical generation in a sample are described. A reaction mixture containing glutathione and a nitroxyl radical, TEMPOL, was caked with gelatin, and then irradiated with a 290 MeV carbon beam. The amount of free radical generation in a solid sample was almost flat from the surface to the beam end, except for a small peak, the peak radioactivation profile, and then steeply decreased approaching the beam end. Total free radical reactions obtained with carbon‐beam irradiation were expected to be less than one‐third of X‐ray irradiation, when the same dose for a deeper target was considered. Both EPR and MRI are useful tools to visualize free radical generation in samples irradiated by a heavy‐ion beam. The EPR‐based method is more sensitive and quantitative than the MRI‐based method; however, the MRI method can achieve high spatial resolution. This study gives the rationale for a redox regulation trial using antioxidant drugs to reduce the side effects on normal tissues in carbon‐beam therapy. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.