Penetration depth measurement of a 6 MeV electron beam in water by magnetic resonance imaging

We demonstrate magnetic resonance imaging (MRI) visualization of a 6 MeV electron beam in ferrous-doped water; a 25 mm penetration depth was measured. Time domain nuclear magnetic resonance was used to investigate the effect of generated free radicals on the free induction decay (FID) in nondoped water; no apparent effects to the FID were observed. We show that MRI visualization of charged particle beams used in medical applications will require exogenous agents to provide contrast enhancement. Published by the American Physical Society under the terms of the <uri xlink:href="http://creativecommons. org/licenses/by/3.0/">Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.