Application of Gadolinium Ion-doped Glaserite to ESR Imaging.

概要

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The imperfections and defects are well known to form in the alkaline metal sulfates after X-ray irradiation. The Gd ion-doped K3Na (SO4) 2 had high susceptibility to X-ray irradiation. The ESR signal of SO3- radical was isotropic and thermally stable in Gd ion-doped K3Na (SO4) 2 irradiated by X-ray. The result described is the application of the Gd ion-doped K3Na (SO4) 2 to the ESR imaging method which can monitor both absorbed dose and irradiation direction. Zupancic-typed coils were used, to produce the magnetic field gradient with a direction for ESR imaging The parallel wires of Zupancic-typed coils were connected to each other and to the current sources, forming four independent current loops to change the direction of magnetic field. The ESR spectra were measured using an X-band ESR spectrometer with a 100 kHz magnetic field modulator and a phase-sensitive detector. The current values of the four loops were controlled by using four regulated DC power supplies controlled by 12 bit D/A converters. A two-dimensional image was reconstructed using a filtered back projection method from the projection data of 180 directions (1-degree steps), which were obtained by using a field gradient of 1.05mT mm-1. The obtained results suggest that the Gd-doped K3Na (SO4) 2 sample can be utilized as the ESR-CT image and the ESR dosimeter in the range from 20μGy to 100 Gy.
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