Preliminary Study of the Feasibility of a Non Crystalline Positron   Emission Tomography Using a Suspension of Superheated Superconducting Grains   (SSG) in High Density Dielectric Matrix (HDDM) as Detector
  Suspensions of superheated superconducting grains are a detecting composite material. Each grain in the supension is a microcalorimeter with an energy threshold defined by its equatorial magnetic field for a given temperature. The higher the matrix density, the larger the gamma stopping power. For several years, cylindrical cells of such suspensions about 2 cm long and 0.4 mm in diameter can be read out in real time. As a result, using two independent cells, one can record a time coincidence between them. This could be potentially very useful for positron cameras where two diametrically opposite cells are simultaneously knocked by 511 keV gammas. This paper, based on the state of art in SSG in high density matrix, discusses such a feasibility. 
Roger Bruhre-Dawson, Jacques Maillard, Girard Maurel, Jorge Silva and   Georges Waysand