VOID-FRACTION RECONSTRUCTION WITH STOCHASTIC DATA

The technique of computerized tomography has been used earlier to meas ure point density (or void-fraction) distribution in air-water flows. The interrogation source used in the measurement system was a gamma ra y source, Cs-137. The inherent nature of such sources is the Poisson n ature of the emmitted radiation. This Poisson corruption leads to impe rfections in the projection data, i.e., the data no longer represents the line integral of the desired property being measured. The present study was conducted to assess the sensitivity of the tomographic recon struction process to the statistical (Poisson) uncertainity in the pro jection data. Reconstruction experiments performed on six different se ts of data indicate that influence of Poisson errors on reconstruction profiles is much more pronounced near the centre of the pipe in all t he cases indicating the need for stronger gamma ray sources than the 1 3.6 milli-Curie used in the earlier investigations.