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Title: Optical Pumping System Design for Large Production of Hyperpolarized {sup 129}Xe

Abstract

We present a design for a spin-exchange optical pumping system to produce large quantities of highly polarized {sup 129}Xe. Low xenon concentrations in the flowing gas mixture allow the laser to maintain high Rb polarization. The large spin-exchange rate between Rb and {sup 129}Xe through the long-lived van der Waals molecules at low pressure, combined with a high flow rate, results in large production rates of hyperpolarized xenon. We report a maximum polarization of 64% achieved for a 0.3 l/h Xe flow rate, and maximum magnetization output of 6 l/h at 22% polarization. Our findings regarding the polarization dependence on temperature, nitrogen partial pressure, and gas mixture flow velocity are also reported.

Authors:
; ;  [1]
  1. Department of Physics, University of New Hampshire, Durham, New Hampshire 03824 (United States)
Publication Date:
OSTI Identifier:
20778590
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 96; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevLett.96.053002; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; FLOW RATE; MAGNETIZATION; MIXTURES; NITROGEN; OPTICAL PUMPING; PARTIAL PRESSURE; POLARIZATION; RUBIDIUM; SPIN EXCHANGE; VAN DER WAALS FORCES; XENON 129

Citation Formats

Ruset, I.C., Ketel, S., and Hersman, F.W. Optical Pumping System Design for Large Production of Hyperpolarized {sup 129}Xe. United States: N. p., 2006. Web. doi:10.1103/PHYSREVLETT.96.0.
Ruset, I.C., Ketel, S., & Hersman, F.W. Optical Pumping System Design for Large Production of Hyperpolarized {sup 129}Xe. United States. doi:10.1103/PHYSREVLETT.96.0.
Ruset, I.C., Ketel, S., and Hersman, F.W. Fri . "Optical Pumping System Design for Large Production of Hyperpolarized {sup 129}Xe". United States. doi:10.1103/PHYSREVLETT.96.0.
@article{osti_20778590,
title = {Optical Pumping System Design for Large Production of Hyperpolarized {sup 129}Xe},
author = {Ruset, I.C. and Ketel, S. and Hersman, F.W.},
abstractNote = {We present a design for a spin-exchange optical pumping system to produce large quantities of highly polarized {sup 129}Xe. Low xenon concentrations in the flowing gas mixture allow the laser to maintain high Rb polarization. The large spin-exchange rate between Rb and {sup 129}Xe through the long-lived van der Waals molecules at low pressure, combined with a high flow rate, results in large production rates of hyperpolarized xenon. We report a maximum polarization of 64% achieved for a 0.3 l/h Xe flow rate, and maximum magnetization output of 6 l/h at 22% polarization. Our findings regarding the polarization dependence on temperature, nitrogen partial pressure, and gas mixture flow velocity are also reported.},
doi = {10.1103/PHYSREVLETT.96.0},
journal = {Physical Review Letters},
number = 5,
volume = 96,
place = {United States},
year = {Fri Feb 10 00:00:00 EST 2006},
month = {Fri Feb 10 00:00:00 EST 2006}
}
  • Low thermal-equilibrium nuclear spin polarizations and the need for sophisticated instrumentation render conventional nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI) incompatible with small-scale microfluidic devices. Hyperpolarized 129Xe gas has found use in the study of many materials but has required very large and expensive instrumentation. Recently a microfabricated device with modest instrumentation demonstrated all-optical hyperpolarization and detection of 129Xe gas. This device was limited by 129Xe polarizations less than 1%, 129Xe NMR signals smaller than 20 nT, and transport of hyperpolarized 129Xe over millimeter lengths. Higher polarizations, versatile detection schemes, and flow of 129Xe over larger distances are desirablemore » for wider applications. Here we demonstrate an ultra-sensitive microfabricated platform that achieves 129Xe polarizations reaching 7%, NMR signals exceeding 1 μT, lifetimes up to 6 s, and simultaneous two-mode detection, consisting of a high-sensitivity in situ channel with signal-to-noise of 10 5 and a lower-sensitivity ex situ detection channel which may be useful in a wider variety of conditions. 129Xe is hyperpolarized and detected in locations more than 1 cm apart. Our versatile device is an optimal platform for microfluidic magnetic resonance in particular, but equally attractive for wider nuclear spin applications benefitting from ultra-sensitive detection, long coherences, and simple instrumentation.« less
  • We investigate {sup 129}Xe-Cs (D{sub 1},D{sub 2}) spin exchange optical pumping (SEOP) at high Xe densities ({approx}0.12-2.44 amagat) using newly available high-power (>40 W) laser diode arrays and compare with {sup 129}Xe-Rb D{sub 1} SEOP under similar conditions. At elevated Xe densities, the spin-exchange rate (per alkali-metal atom, {gamma}{sup '}) for Cs-{sup 129}Xe is {approx}1.5-fold greater than that for Rb-{sup 129}Xe. Higher spin-exchange rates and lower {sup 129}Xe spin-destruction rates for Cs-{sup 129}Xe versus Rb-{sup 129}Xe contribute to {approx}twofold improvement in {sup 129}Xe nuclear spin polarization measured at 9.4 T - with the largest gains observed at the highest Xemore » densities.« less
  • The major obstacle to the use of 129-xenon (I = {1/2}) as a new source of contrast in magnetic resonance is its low sensitivity. The hyperpolarized {sup 129}Xe-MRI technique using laser optical pumping of rubidium promises to resolve this problem. The potential of xenon-based MRI for the body tissues other than the lung air spaces depends on the {sup 129}Xe polarization lifetime (T1) in the blood at a magnetic field of commonly available clinical MRI systems. Xenon with natural abundance of {sup 129}Xe (26%) was dissolved in human blood and studied at 36{degrees}C in a 2.35 T 40 cm boremore » MRI spectrometer (27.6 MHz). Zeeman relaxation (T1) of six blood samples was measured by the progressive saturation method for periods of 4-8 h each. NMR spectra revealed two peaks at 216.0 ppm (A) and 194.0 ppm (B) relative to the xenon gas above the blood volume. Assignment and {sup 129}Xe T1 values were 4.5 {+-} 1 s for red blood cells (A), 0.6 {+-} 2 s for plasma (B) and 11.9 {+-} 1.6 s for xenon gas at atmospheric oxygen pressure. Xenon dissolved in distilled water appears at 189.8 ppm and has T1 = 26.3 {+-} 1.4 s. These relaxation times, though shorter than expected, are comparable to the transport time of blood, and are long enough to encourage use of hyperpolarized xenon for MRI studies in tissues, in addition to lung. 18 refs., 2 figs.« less
  • Studies of hyperpolarized xenon-129 in media such as liquid crystals and cell suspensions are in demand for applications ranging from biomedical imaging to materials engineering but have been hindered by the inability to bubble Xe through the desired media as a result of viscosity or perturbations caused by bubbles. This research reports on a device that can be reliably used to dissolve hp- 129 Xe into viscous aqueous and organic samples without bubbling. This method is robust, requires small sample volumes ( < 60 μL), is compatible with existing NMR hardware, and is made from readily available materials. Experiments showmore » that Xe can be introduced into viscous and aligned media without disrupting molecular order. We detected dissolved xenon in an aqueous liquid crystal that is disrupted by the shear forces of bubbling, and we observed liquid-crystal phase transitions in (MBBA). This tool allows an entirely new class of samples to be investigated by hyperpolarized-gas NMR spectroscopy. Blending into the crowd: A new device that facilitates the direct dissolution of hyperpolarized 129 Xe into viscous liquid-crystalline media is presented. 129 Xe and 2 H NMR spectra show the nondisruptive dissolution of xenon, the presence of ordered phases, and, in the case of the thermotropic liquid crystal N-(4-methoxybenzylidene)-4-butylaniline, a nematic-isotropic phase transition.« less
  • Purpose: Radiation induced lung injury (RILI) is a common side effect for patients undergoing thoracic radiation therapy (RT). RILI can lead to temporary or permanent loss of lung function and in extreme cases, death. Combining functional lung imaging information with conventional radiation treatment plans may lead to more desirable treatment plans that reduce lung toxicity and improve the quality of life for lung cancer survivors. Magnetic Resonance Imaging of the lung following inhalation of hyperpolarized{sup 129}Xe may provide a useful nonionizing approach for probing changes in lung function and structure associated with RILI before, during, or after RT (early andmore » late time-points). Methods: In this study, dynamic{sup 129}Xe MR spectroscopy was used to measure whole-lung gas transfer time constants for lung tissue and red blood cells (RBC), respectively (T{sub Tr-tissue} and T{sub Tr-RBC}) in groups of rats at two weeks and six weeks following 14 Gy whole-lung exposure to radiation from a {sup 60}Co source. A separate group of six healthy age-matched rats served as a control group. Results: T{sub Tr-tissue} values at two weeks post-irradiation (51.6 ± 6.8 ms) were found to be significantly elevated (p < 0.05) with respect to the healthy control group (37.2 ± 4.8 ms). T{sub Tr-RBC} did not show any significant changes between groups. T{sub Tr-tissue} was strongly correlated with T{sub Tr-RBC} in the control group (r = 0.9601 p < 0.05) and uncorrelated in the irradiated groups. Measurements of arterial partial pressure of oxygen obtained by arterial blood sampling were found to be significantly decreased (p < 0.05) in the two-week group (54.2 ± 12.3 mm Hg) compared to those from a representative control group (85.0 ± 10.0 mm Hg). Histology of a separate group of similarly irradiated animals confirmed the presence of inflammation due to radiation exposure with alveolar wall thicknesses that were significantly different (p < 0.05). At six weeks post-irradiation, T{sub Tr-tissue} returned to values (35.6 ± 9.6 ms) that were not significantly different from baseline. Conclusions: Whole-lung tissue transfer time constants for{sup 129}Xe (T{sub Tr-tissue}) can be used to detect the early phase of RILI in a rat model involving 14 Gy thoracic {sup 60}Co exposure as early as two weeks post-irradiation. This knowledge combined with more sophisticated models of gas exchange and imaging techniques, may allow functional lung avoidance radiation therapy planning to be achievable, providing more beneficial treatment plans and improved quality of life for recovering lung cancer patients.« less