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Fast high‐resolution 3D segmented echo planar imaging for dose mapping using a superheated emulsion chamber
Author(s) -
Lamba Michael,
Holland Scott K.,
Schmithorst Vincent,
Dardzinski Bernard,
d'Errico Francesco,
Nath Ravinder
Publication year - 2003
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.10414
Subject(s) - microbubbles , materials science , irradiation , vaporization , brachytherapy , dosimetry , superheating , biomedical engineering , chemistry , nuclear medicine , ultrasound , radiation therapy , physics , radiology , acoustics , nuclear physics , medicine , organic chemistry , condensed matter physics
The superheated emulsion chamber (SEC) consists of superheated droplets of halocarbons in an aqueous gel. The gel resides in a pressure chamber. Brachytherapy sources can be implanted in the SEC for radiation dosimetry studies. Upon irradiation by ionizing radiation, the metastable droplets vaporize to form microbubbles. MRI can be used to determine the distribution of bubbles following irradiation of the SEC. In order to generate sufficient statistical accuracy in the determination of dose distributions around brachytherapy sources, it is necessary to use hundreds of irradiation cycles. Susceptibility‐weighted images provide contrast between the gel and the vapor microbubbles. This article describes a 3D, blipped, double‐sampled, segmented echo‐planar imaging technique for rapidly imaging the SEC at 650 μm isotropic 3D resolution in about 2 min. This method was used with a pressure cycling SEC to acquire hundreds of images in several hours. Results are presented showing the 2D dose distribution generated by an 125 I source as measured in the SEC using this new imaging method. Magn Reson Med 49:675–681, 2003. © 2003 Wiley‐Liss, Inc.