T. Pałasz

A high-field 3He metastability exchange optical pumping polarizer operating in a 1.5 T medical scanner for lung magnetic resonance imaging

After being hyperpolarized using the technique of Metastability Exchange Optical Pumping (MEOP), 3He can be used as a contrast agent for lung magnetic resonance imaging (MRI). MEOP is usually performed at low magnetic field (∼1 mT) and low pressure (∼1 mbar), which results in a low magnetization production rate. Polarization preserving compression with a compression ratio of order 1000 is also required. It was demonstrated in sealed cells that high nuclear polarization values can be obtained at higher pressures with MEOP, if performed at high magnetic field (non-standard conditions). In this work, the feasibility of building a high-field polarizer that operates within a commercial 1.5 T scanner was evaluated. Preliminary measurements of nuclear polarization with sealed cells filled at different 3He gas pressures (1.33 to 267 mbar) were performed. The use of an annular shape for the laser beam increased by 25% the achievable nuclear polarization equilibrium value (Meq) at 32 and 67 mbar as compared to a Ga...

Magnetic resonance imaging using optically polarized 3He

Magnetic resonance imaging (MM) using optically polarized 3He is a new and very promising diagnostic method for studying structure and function of lungs. A novel low field MRI system based on permanent magnet and a home-built 3He polarizing unit is presented. The system is designed to perform experiments on small animals. First 1H and 3He images of phantoms small biological objects and rat lungs in vivo are shown.

Tunable semiconductor weak-power diode lasers and their second harmonic for atomic absorption spectroscopy

The construction of a single mode semiconductor diode laser spectrometer that can be tuned electronically by temperature as well as current is presented. The laser was tested by tuning to the rubidium resonant line (780.2 nm):5s2S1/2 - 5p2P3/2. By using a lithium iodate crystal the primary infrared light (830 nm) emitted by a Sharp LTO- 15PT diode laser was successfully converted into the secondary light wave.