COUPLING SCINTILLATION LIGHT INTO OPTICAL-FIBER FOR USE IN A COMBINEDPET-MRI SCANNER

We investigate the specific problem of efficient coupling and transmis sion of light from a small inorganic crystal into optical fibre. The l ong-term goal of our project is the construction of a dual Positron Em ission Tomography (PET)-Magnetic Resonance Imaging (MRI) scanner. The technique discussed in this paper can efficiently transport the scinti llator light out of the high magnetic field and constrained spatial vo lume of the MRI magnet bore to a convenient and low-field region meter s away without affecting the homogeneity of the MRI field. Presented a re measurements and calculations on the coupling and transmission of l ight created in a 2.45 x 2.45 x 10 mm crystal of LSO suitable for high -resolution PET. We find that a solution for transport of the light pa rticular to our PET-MRI interests is via optical fibre bundles of 200 mu m core fibres butted against the end of the crystal. These small co re fibres are better suited than their larger diameter counterparts as they permit a smaller bending radius and have a similar packing fract ion. Our results indicate that the small LSO crystal butted to a hexag onally packed bundle of 176 fibres of 3 m length produces adequate sci ntillation light for PET applications.