Fiber-Optic Bragg Gratings for Temperature and Pressure Measurements in Isotope Production Targets for Nuclear Medicine

Michael Bakaic,S Stefan Zeisler,Dan Grobnic,Cyril Hnatovsky,Matthew Hanna,Cornelia Hoehr,Stephen Mihailov

doi:10.3390/app10134610

Michael Bakaic, S Stefan Zeisler + Show 5 more

Open Access

https://doi.org/10.3390/app10134610

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Journal: Applied Sciences	Publication Date: Jul 3, 2020
Citations: 8	License type: CC BY 4.0

Affiliation: TRIUMF, National Research Council Canada

Abstract

A Bragg grating inscribed into an inorganic optical fiber was tested in proton and neutron fields up to doses of 472 Gy. Observation showed that radiation had no effect on the performance of the Fiber Bragg Grating (FBG) used as a gauge measuring temperature and pressure. The FBG sensor was subsequently employed to measure the temperature and pressure inside a liquid isotope production target for nuclear medicine. The fiber Bragg grating measured the temperature and pressure of a water target as a 12 MeV proton beam impinged on it in real time and was tested with beam currents of up to 20 µA.

Highlights

Every year, over forty million people worldwide receive nuclear medical imaging (PositronEmission Tomography (PET) or Single-Photon Emission Computed Tomography (SPECT) in the course of their treatment [1]
The placards featured one specimen of each of the three categories of Fiber Bragg Grating (FBG) installed in a strain relieved manner in a designated target
Spectra of each FBG specimen were collected before, during and after irradiation to assess the impact of the irradiation on two key parameters: changes to the reflected power of the FBG, labelled as Radiation Induced Absorption (RIA), and changes to the characteristic

Summary

Introduction

Over forty million people worldwide receive nuclear medical imaging (PositronEmission Tomography (PET) or Single-Photon Emission Computed Tomography (SPECT) in the course of their treatment [1]. The required radioactive isotopes can be produced on a medical cyclotron, using solid [2], liquid [3] and gaseous [4] target materials, enclosed in a metal vessel. Other effects like target body and transfer line material, density reduction due to temperature increases during irradiation, convective currents and phase changes may have an effect on the recoverable radionuclidic yield [5,6,7,8]. The pressure is measured either in the target body instead of the actual target gas or liquid [13] or on a line connected to the target volume [5]. As the pressure transducer may be located at a distance of several meters away from the target, its reading may not necessarily reflect the true conditions in the target

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